Co-reporter:L. Chen, J. L. Bao, X. Dong, D. G. Truhlar, Y. Wang, C. Wang, and Y. Xia
ACS Energy Letters May 12, 2017 Volume 2(Issue 5) pp:1115-1115
Publication Date(Web):April 18, 2017
DOI:10.1021/acsenergylett.7b00040
The magnesium-metal battery, which consists of a cathode, a Mg-metal anode, and a nonaqueous electrolyte, is a safer and less expensive alternative to the popular Li-ion battery. However, the performance of Mg batteries is greatly limited by the low electrochemical oxidative stability of nonaqueous electrolytes, the slow Mg2+ diffusion into the cathode, and the irreversibility of Mg striping and plating on the Mg metal anode. Here, we report the first Mg-ion battery using a Mg2+ aqueous electrolyte, nickel hexacyanoferrate cathode, and polyimide anode. The operation depends on Mg2+ intercalation–deintercalation at the cathode and reversible enolization at the anode, accompanied by Mg2+ transport between cathode and anode. The cell exhibits a maximum cell voltage of 1.5 V and a supercapacitor-like high power, and it can be cycled 5000 times. This system points the way to improved Mg-based rechargeable batteries.
Co-reporter:Zhaowei Guo, Long Chen, Yonggang WangCongxiao Wang, Yongyao Xia
ACS Sustainable Chemistry & Engineering February 6, 2017 Volume 5(Issue 2) pp:
Publication Date(Web):January 4, 2017
DOI:10.1021/acssuschemeng.6b02127
Polyimide/activated carbon (PI/AC) composites were prepared by in situ polymerization of 1,4,5,8-naphthalenete-tracarboxylic dianhydride (NTCDA) and ethylene diamine (EDA) on activated carbon with various mass ratios varying from 50:50 to 70:30. These composites were examined as anode materials in 5 M LiNO3 solution in the potential window from −0.75 to 0 V vs Ag/AgCl. With an optimal composition PI/AC 50:50 in mass ratio, the composite delivers a specific capacity of 87 mAh g–1 at a current density of 0.2 A g–1, and it also shows excellent cycling stability and rate capability. A sealed full cell containing a PI/AC composite anode and LiMn2O4 cathode delivers a specific capacity of 42 mAh g–1 and energy density of 51Wh kg1– (based on the total weight of both active materials) at a current density of 0.2 A g–1. The full cell exhibits good cycling stability with a specific capacity of 35 mAh g–1 after 450 cycles, corresponding to a capacity retention of 89%.Keywords: Activated carbon; Aqueous lithium-ion battery; Composite anode; LiMn2O4; Polyimide;
Co-reporter:Wangyu Li, Long Chen, Yunhe Sun, Congxiao Wang, Yonggang Wang, Yongyao Xia
Solid State Ionics 2017 Volume 300(Volume 300) pp:
Publication Date(Web):1 February 2017
DOI:10.1016/j.ssi.2016.12.013
•An all-solid-state battery was fabricated by using a solid polymer as electrolyte and an organic material as cathode.•This battery shows a better cycle life. The capacity retention was 74% at 0.1 C (20 mA g− 1) after 50 cycles.•Lithium battery using the polymer electrolyte shows an enhanced thermal stability.An all-solid-state battery was fabricated by using a PEO-base solid polymer as electrolyte and an organic material anthraquinone (AQ) as cathode. The anthraquinone delivers a specific discharge capacity of 183 mAh g− 1 at first cycle at current density of 20 mA g− 1 at 65 °C. The use of solid polymer electrolyte reduces the dissolution of organic active material greatly, improving the cycle performance of the battery. Therefore, the all-solid-state battery delivers a better cycling property. It can still retain a capacity of 136 mAh g− 1 after 50 cycles, corresponding to a capacity retention of 74%, while capacity retention of the cell using liquid electrolyte was only 28% after 20 cycles. The all-solid-state battery shows more stable interfacial resistance during charge–discharge process. It displays good rate ability and a better thermal stability.The all-solid-state battery using solid polymer electrolyte and anthraquinone cathode displays better cycling life, good rate capability and improved thermal stability.Download high-res image (132KB)Download full-size image
Co-reporter:Long Fan;Yao Liu;Andebet Gedamu Tamirat;Yonggang Wang;Yongyao Xia
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 21) pp:13060-13066
Publication Date(Web):2017/10/24
DOI:10.1039/C7NJ02668D
ZnSb@C microflower composites have been fabricated through C2H2-pyrolysis by the reduction of microflower-like Zn(OH)2–Sb2O3 precursors. The as-formed ZnSb particles are uniformly dispersed in the synchronously formed continuous amorphous carbon matrix. Meanwhile, the flower-like morphology of the precursors has been maintained after the reducing process. As anodes for Li-ion and Na-ion batteries, the as-prepared ZnSb@C microflower composite anode exhibits a reversible capacity of 480.5 mA h g−1 at 100 mA g−1 after 240 cycles for Li-ion batteries and a reversible capacity of 393.4 mA h g−1 at 50 mA g−1 after 240 cycles for Na-ion batteries, which are much better than those of the ZnSb–C particle composites. The enhanced electrochemical performance can be attributed to the special microflower-like and porous structure as well as the synchronously formed continuous amorphous carbon matrix.
Co-reporter:Yao Liu;Jingyuan Liu;Mengyan Hou;Long Fan;Yonggang Wang;Yongyao Xia
Journal of Materials Chemistry A 2017 vol. 5(Issue 22) pp:10902-10908
Publication Date(Web):2017/06/06
DOI:10.1039/C7TA03173D
Sodium-ion batteries have been considered as promising alternatives to the current lithium-ion batteries owing to their low cost and abundant raw material. The major challenge of their practical implementation is the lack of favourable anode material. Spinel Li4Ti5O12 has been regarded as a potential anode material for its superior capability of sodium-ion storage and relatively appropriate operating voltage. However, the low intrinsic ionic and electronic conductivity of spinel Li4Ti5O12 still remains as its major drawback. Herein, carbon-coated Li4Ti5O12 nanoparticles have been synthesized through a solid-state reaction and a chemical vapour deposition method and used as an anode material for sodium-ion battery. The composite structure demonstrates excellent stability and an initial discharge specific capacity of 120.1 mA h g−1, which is maintained at 101.5 mA h g−1 after 500 cycles corresponding to 85% of capacity retention at a current density of 0.1 A g−1. In addition, a full cell was fabricated with carbon-coated Na3V2(PO4)3 as a positive electrode, which displayed discharge specific capacities of 138.5 mA h g−1 that was maintained at 114.7 mA h g−1 after 50 cycles at a current density of 0.05 A g−1, and the capacity retention was 82.8%. The results indicated that the Li4Ti5O12 nanoparticle with a carbon layer shows a promising electrochemical performance as anode materials in sodium-ion batteries.
Co-reporter:Ying Pang;Yunping Wen;Wangyu Li;Yunhe Sun;Tiancheng Zhu;Yonggang Wang;Yongyao Xia
Journal of Materials Chemistry A 2017 vol. 5(Issue 34) pp:17926-17932
Publication Date(Web):2017/08/29
DOI:10.1039/C7TA04852A
Lithium–sulfur batteries are regarded as promising candidates for energy storage devices owing to their high theoretical energy density. However, severe self-discharge due to the dissolution and shuttle effect of polysulfides hinders the practical application of Li–S batteries. In this work, we present a strategy to entrap sulfur in a mesoporous FePO4/carbon nanocomposite that relies on a chemical process, in which FePO4 bonds with sulfur to form S–O chemical bonds for high performance Li–S batteries. The prepared S/FePO4/C nanocomposite exhibits excellent cycling performance. It delivers an initial discharge capacity of 953.8 mA h g−1 and a discharge capacity of 550.8 mA h g−1 can be reserved after successive cycling for 500 cycles with a capacity decay rate of 0.05% per cycle at 0.5C. Also, the S/FePO4/C electrode exhibits extremely low self-discharge behavior. The cell voltage is stabilized at a high value of approximately 2.9 V after 7 days' rest with S/FePO4/C as the cathode. Even after 30 days' rest, the potential is still maintained at about 2.7 V, demonstrating an extremely low rate of self-discharge. In addition, both the areal capacity and the volumetric capacity of the S/FePO4/C electrode are superior to those of the S/carbon electrode, indicating its promising application in practical Li–S batteries.
Co-reporter:Yao Liu, Yirong Zhou, Junxi ZhangYongyao Xia, Tong ChenShiming Zhang
ACS Sustainable Chemistry & Engineering 2017 Volume 5(Issue 2) pp:
Publication Date(Web):December 14, 2016
DOI:10.1021/acssuschemeng.6b01536
Sodium iron phosphate (Na3Fe2(PO4)3) as cathode material for sodium-ion batteries has been synthesized through a simple method of a solid state reaction. It crystallizes in a monoclinic structure in the space group C2/c. The morphology of the as-prepared sample has been investigated by scanning electron microscopy and transmission electron microscopy. The charge/discharge curves show a very flat plateau at about 2.5 V (vs Na/Na+). The initial specific discharge capacity is 61 mAh g–1 and remains at 57 mAh g–1 after 500 cycles at a current rate of 1 C. X-ray photoelectron spectroscopy measurements indicate that not all of the Fe3+ of Na3Fe2(PO4)3 is reduced during the electrochemical process. The ex-situ X-ray diffraction measurements were applied to research the mechanism of sodium-ion storage; the results indicated that the Na3Fe2(PO4)3 compound partly transformed into Na4Fe2(PO4)3 and Na3+xFe2(PO4)3 compound. These results testify to the potential of monoclinic Na3Fe2(PO4)3 as a cathode material in sodium-ion batteries.Keywords: Ex-situ X-ray diffraction; NASICON; Sodium iron phosphate; Sodium-ion diffusion coefficient; Solid state synthesis; X-ray photoelectron spectroscopy;
Co-reporter:Duan Bin;Ziyang Guo;Andebet Gedamu Tamirat;Yuanyuan Ma;Yonggang Wang;Yongyao Xia
Nanoscale (2009-Present) 2017 vol. 9(Issue 31) pp:11148-11157
Publication Date(Web):2017/08/10
DOI:10.1039/C7NR03009F
The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are traditionally carried out using noble metals (such as Pt) and metal oxides (such as RuO2 and IrO2) as catalysts, respectively. Nevertheless, several key issues such as high cost, poor stability, and detrimental environmental effects limit the catalytic activity of these noble metal- and metal oxide-based catalysts. Herein, we have designed and synthesized macroporous carbon nanofiber arrays by using a natural crab shell template. Subsequently, spinel MnCo2O4 nanoparticles were embedded into the nitrogen-doped macroporous carbon nanofiber arrays (NMCNAs) by a hydrothermal method. Accompanied by the good conductivity, large surface area and doping of nitrogen, the as-prepared MnCo2O4/NMCNA exhibited remarkable catalytic performance and outstanding stability for both ORR and OER in alkaline media. The macroporous superstructures play vital role in reducing the ion transport resistance and facilitating the diffusion of gaseous products (O2). Finally, rechargeable Zn–air batteries using the MnCo2O4/NMCNA catalyst displayed appreciably lower overpotentials, higher power density and better stability than commercial Pt/C, thus raising the prospect of functional low-cost, non-precious-metal bifunctional catalysts in metal–air batteries.
Co-reporter:Jingyuan Liu, Mengyan Hou, Yue Shen, Long Chen, Yonggang Wang, Yongyao Xia
Electrochimica Acta 2017 Volume 241(Volume 241) pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.electacta.2017.04.093
Li4Ti5O12 as one of the commercialized materials, is famous for its excellent reversibility, but also suffered from two drawbacks- low theoretical capacity and difficulty in SOC estimation. In this study, we report a Li4Ti5O12 nanowire/Fe3O4 nanoparticle compound synthesized by hydrothermal method as anode material for lithium ion battery. By in-situ synthesizing Fe3O4 nanoparticles on the surface of Li4Ti5O12 nanowire, particle size of Fe3O4 is remarkably reduced and this resulting in good reversibility of electrode. Moreover, this Li4Ti5O12 nanowire/Fe3O4 nanoparticle compound exhibits much larger capacity than pure-phase Li4Ti5O12. And most importantly, the Li4Ti5O12 nanowire/Fe3O4 nanoparticle compound displays a slope voltage profile, which makes the voltage based SOC estimation much easier than Li4Ti5O12.
Co-reporter:Wangyu Li;Ying Pang;Jingyuan Liu;Guanghui Liu;Yonggang Wang;Yongyao Xia
RSC Advances (2011-Present) 2017 vol. 7(Issue 38) pp:23494-23501
Publication Date(Web):2017/04/27
DOI:10.1039/C7RA02603J
A lithium-ion conducting gel polymer electrolyte (GPE) membrane containing PEO as a polymer host and liquid electrolyte has been prepared by a simple one-step procedure. The prepared electrolyte membrane exhibits a good ionic conductivity of 3.3 × 10−3 S cm−1 and high lithium transference number of 0.76 at room temperature. Meanwhile, the gel polymer electrolyte membrane shows very good thermal stability. A Li/GPE/LiFeO4 cell was fabricated to demonstrate the electrochemical performance of the GPE. The cell exhibits good cycling stability with a high capacity retention of 81% after 500 cycles and as good a rate performance as LiFeO4 tested in liquid electrolyte.
Co-reporter:Jingyuan Liu;Wei Kong Pang;Tong Zhou;Long Chen;Yonggang Wang;Vanessa K. Peterson;Zhongqin Yang;Zaiping Guo;Yongyao Xia
Energy & Environmental Science (2008-Present) 2017 vol. 10(Issue 6) pp:1456-1464
Publication Date(Web):2017/06/14
DOI:10.1039/C7EE00763A
To date, anode materials for lithium-ion batteries (LIBs) have been dominated by carbonaceous materials, which have a low intercalation potential but easily allow lithium dendrites to form under high current density, leading to a safety risk. The other anode material, the “zero-strain” spinel-structured Li4Ti5O12, with a ∼1.5 V vs. Li+/Li intercalation potential, exhibits excellent cycling stability and avoids the issues of dendrite growth and Li plating. The low capacity and high voltage of Li4Ti5O12, however, result in low energy density. Herein, we report a new and environmentally friendly anode material, Li2TiSiO5, which delivers a capacity as high as 308 mA h g−1, with a working potential of 0.28 V vs. Li+/Li, and excellent cycling stability. The lithium-storage mechanism of this material is also proposed based on the combination of in situ synchrotron X-ray diffraction, neutron powder diffraction with Fourier density mapping, ex situ X-ray absorption near edge structure analysis, ex situ transmission electron microscopy, and density-functional theory calculations with the projector-augmented-wave formalism. The lithium-storage mechanism of this material is shown to involve a two-electron (Ti4+/Ti2+ redox) conversion reaction between TiO and Li4SiO4.
Co-reporter:Yunping Wen, Long Chen, Ying Pang, Zhaowei Guo, Duan Bin, Yong-gang WangCongxiao Wang, Yongyao Xia
ACS Applied Materials & Interfaces 2017 Volume 9(Issue 9) pp:
Publication Date(Web):February 17, 2017
DOI:10.1021/acsami.6b14856
This paper reports a facile sol–gel synthesis method to successfully prepare the TiP2O7/expanded graphite (EG) nanocomposite as an advanced anode material for aqueous lithium-ion batteries. The constructed TiP2O7 nanocomposites (50–100 nm) are in situ encapsulated in the pore and layer structure of expanded graphite with good conductivity and high specific surface area. As a consequence, the resulting TiP2O7/EG electrode exhibits a reversible capacity of 66 mAh g–1 at 0.1 A g–1 with an appropriate potential of −0.6 V before hydrogen evolution in aqueous electrolytes, and also demonstrates greatly enhanced cycling stability with 75% capacity retention after 1000 cycles at the current density of 0.5 A g–1. A full cell consisting of TiP2O7/EG anode, LiMn2O4 cathode, and 1 M Li2SO4 electrolyte delivers a specific energy of 60 Wh kg–1 calculated on the weight of both cathode and anode materials with an operational voltage of 1.4 V. It also exhibits superior rate capability and remarkable cycling performance with a capacity maintenance of 66% over 500 cycles at 0.2 A g–1 and 61% at 1 A g–1 over 2000 cycles.Keywords: anode materials; aqueous lithium-ion batteries; expanded graphite; H2 evolution reaction; TiP2O7;
Co-reporter:Lina Wang, Jingyuan Liu, Shouyi Yuan, Yonggang Wang and Yongyao Xia
Energy & Environmental Science 2016 vol. 9(Issue 1) pp:224-231
Publication Date(Web):13 Nov 2015
DOI:10.1039/C5EE02837J
Li–S batteries generally suffer from severe self-discharge when resting due to an internal polysulfide shuttle effect. Soluble long-chain polysulfide species (Li2Sx, 4 ≤ x ≤ 8) would continue to dissolve and migrate to the negative side to react with metallic Li. Here, we demonstrate pronounced suppression of polysulfide shuttle using an ionic liquid of the N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide (PP13TFSI)-based electrolyte. When working in combination with LiNO3, zero self-discharge can be achieved to rest a full-charged Li–S cell for two days. The fascinating study clearly demonstrates that a promising practical Li–S battery with low self-discharge depends on both improvements on polysulfide diffusion control and Li-metal stabilization.
Co-reporter:Jun Yang and Yongyao Xia
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 2) pp:1297
Publication Date(Web):December 23, 2015
DOI:10.1021/acsami.5b09938
The layered Ni-rich oxide cathode (LiNi0.8Co0.1Mn0.1O2) suffers from a tremendous structural degradation during high-voltage cycling (4.8 V), causing the drastic rise of electrode impedance and deterioration of the capacity retention. Here, we develop an effective strategy to overcome these problems of the Ni-rich cathode material through doping low-content Li2MnO3 as an excellent structure stabilizer. Cyclic voltammogram and ex-situ X-ray diffraction measurements have reveled that Li2MnO3 could display a remarkable suppression effect on the phase transition of LiNi0.8Co0.1Mn0.1O2. The electrochemical tests showed that Li2MnO3-stabilized LiNi0.8Co0.1Mn0.1O2 could realize the large reversible capacity, stable discharge voltage and excellent cycling life during high-voltage cycling, which could be benefited from the enhanced structural stability of the modified Ni-rich cathode. The Li2MnO3 could sufficiently suppress the phase transition between two hexagonal phase (H2 and H3) with distinctly different lattice parameters, significantly reducing variation of unit-cell volume, which facilitates stabilization of the original layered structure of LiNi0.8Co0.1Mn0.1O2 cathode during high-voltage cycling.Keywords: layered structure; Li-ion battery; Ni-rich oxide cathode; phase transition
Co-reporter:Shuang Hu, Yanfang Song, Shouyi Yuan, Haimei Liu, Qunjie Xu, Yonggang Wang, Cong-Xiao Wang, Yong-Yao Xia
Journal of Power Sources 2016 Volume 303() pp:333-339
Publication Date(Web):30 January 2016
DOI:10.1016/j.jpowsour.2015.11.015
•Carbon-coated Li3VO4 embedded in expanded graphite has been synthesized at one step.•High electronic conductivity and mechanical stability are obtained.•Rate and cycling performance largely improved as for lithium ion battery.A hierarchical structure of carbon-coated Li3VO4 nanoparticles homogeneously embedded in expanded graphite was successfully synthesized by a facile and scalable sol–gel method. In the constructed architecture, high electronic conductivity of expanded graphite serves as a loading carrier, enabling the fast transmission of electronics. The thin outside carbon shells protect the Li3VO4 nanoparticles from direct exposure to the electrolyte and mitigate unwanted interfacial side reactions. As a consequence, the hybrid material exhibits greatly enhanced cycle and rate capability compared with pristine Li3VO4: a reversible gravimetric capacity of 405 mAh g−1 obtained at 100 mA g−1 with 89% retention after 200 cycles, and 205.5 mAh g−1 obtained after 2000 cycles at a heavy current of 2000 mA g−1, as well as an remarkable rate performance of 62.7% capacity maintaining at 6400 mA g−1 (vs. 100 mA g−1).
Co-reporter:Lars Riekehr, Jinlong Liu, Björn Schwarz, Florian Sigel, Ingo Kerkamm, Yongyao Xia, Helmut Ehrenberg
Journal of Power Sources 2016 Volume 325() pp:391-403
Publication Date(Web):1 September 2016
DOI:10.1016/j.jpowsour.2016.06.014
•TEM nano structure analysis of cycled Li-rich NCM composite structures.•Synchrotron XRD of cycled Li-rich NCM composite structures.•Irreversible oxygen loss and LiMnO2 formation.•Reversible anionic redox activity and peroxide formation.•Nanotwin and spinel formation during initial cycle and subsequent cycling.Two different Li-rich nickel–cobalt–manganese-oxide (Li-rich NCM) active materials with the same nominal composition 0.5Li2MnO3:0.5Li(Ni1/3Co1/3Mn1/3)O2 but different pristine nano structure have been analyzed structurally and electrochemically in different cycling states. For structural characterization, transmission electron microscopy (TEM) and high resolution synchrotron powder diffraction (S-XRD) experiments were conducted. The changes in structure with increasing cycle number are correlated with characteristic features in the corresponding electrochemical dQ/dV-profiles that were obtained by galvanostatically cycling the two different active materials. The presented data demonstrates that structural changes upon cycling, e.g. LiMnO2 and spinel formation, strongly depend on the degree oxygen is involved in the reversible charge compensation for delithiation/lithiation. According to our data, firstly a twin-like environment with nanometer dimensions is formed within the R-3m matrix during the initial cycle, which then gradually transforms into a spinel-like structure with increasing cycle number. As another result, we can show that Li2MnO3 to LiMnO2 transformation is not directly dependent in the irreversible oxygen loss in the first cycle but more importantly on transition metal migration. A model is presented explaining the dependency of LiMnO2 and spinel formation on the ability of Li-rich active materials to include oxygen in the charge compensation process.
Co-reporter:Jun Yang, Mengyan Hou, Servane Haller, Yonggang Wang, Congxiao Wang, Yongyao Xia
Electrochimica Acta 2016 Volume 189() pp:101-110
Publication Date(Web):20 January 2016
DOI:10.1016/j.electacta.2015.12.080
The layered Ni-rich oxide LiNi0.8Co0.1Mn0.1O2 cathode has been significantly attractive due to its large reversible capacity (∼200 mAh g−1). However, the inherent poor cycling stability of the Ni-based cathode materials is always a serious issue for restricting its commercialization. In this paper, we introduced Li2MnO3 as an electrochemical inactive component in Ni-rich oxide LiNi0.8Co0.1Mn0.1O2 to stabilize its structure. The modified LiNi0.8Co0.1Mn0.1O2 composites with low-content Li2MnO3 were prepared by a solid-state reaction process. The results from XRD structure refinement and SAED confirm that Li2MnO3 phase exists homogeneously in the composites. The modified LiNi0.8Co0.1Mn0.1O2 composites with inactive Li2MnO3 show much better cycling stability and stable average discharge voltage compared with the pristine one when charged to 4.5 V. Especially, the modified LiNi0.8Co0.1Mn0.1O2 composite with 10% Li2MnO3 (LNCMO-1090) delivers a reversible capacity of 207 mAh g−1 and keeps 155 mAh g−1 after 100 cycles at 20 mA g−1 (0.1C), corresponding to a capacity retention of 75%, while LiNi0.8Co0.1Mn0.1O2 could only maintain a capacity of 128 mAh g−1 with a capacity retention of 59% after 100 cycles. The improved cycling performance of the Li2MnO3-containing electrode could be attributed to the stabilized effect of Li2MnO3 on the electrode surface structure, as evidenced by the lower charge-transfer resistance.
Co-reporter:Fei Wang;Guorui Chen;Wei Li;Yonggang Wang;Congxiao Wang;Yuanbo Zhang;Yongyao Xia
Advanced Materials Interfaces 2016 Volume 3( Issue 3) pp:
Publication Date(Web):
DOI:10.1002/admi.201500496
Co-reporter:Lars Riekehr, Jinlong Liu, Björn Schwarz, Florian Sigel, Ingo Kerkamm, Yongyao Xia, Helmut Ehrenberg
Journal of Power Sources 2016 306() pp: 135-147
Publication Date(Web):29 February 2016
DOI:10.1016/j.jpowsour.2015.11.082
Co-reporter:Xiaoli Dong;Long Chen;Jingyuan Liu;Servane Haller;Yonggang Wang;Yongyao Xia
Science Advances 2016 Volume 2(Issue 1) pp:e1501038
Publication Date(Web):22 Jan 2016
DOI:10.1126/sciadv.1501038
Environmentally-friendly aqueous Li (or Na)-ion battery with super-long life is built for large-scale energy storage.
Co-reporter:Lina Wang, Yonggang Wang and Yongyao Xia
Energy & Environmental Science 2015 vol. 8(Issue 5) pp:1551-1558
Publication Date(Web):11 Mar 2015
DOI:10.1039/C5EE00058K
Lithium–sulfur (Li–S) batteries are receiving intense interest because their promise for low-cost and high-energy electrochemical storage exceeds that of Li-ion batteries. Fully-lithiated lithium sulfide (Li2S) is more desirable than sulfur as a high capacity cathode material because it allows the use of a variety of lithium-free anode materials. Widespread application of Li2S is hindered by severe drawbacks associated with the solubility of the intermediate charge products, and the insulating nature of Li2S. Here, we report the feasibility of utilizing Li2S with a dual-phase electrolyte separated by a lithium super ionic conductor (LISICON). With this cell architecture that enables an efficient utilization of micro-sized Li2S, the Li–S battery yields high specific capacity, Coulombic efficiency, cycling stability, and no self-discharge. A Li-ion sulfur battery with an aluminium or graphite anode is demonstrated as well in our initial proof-of-concept study.
Co-reporter:Fei Wang, Wei Li, Mengyan Hou, Chao Li, Yonggang Wang and Yongyao Xia
Journal of Materials Chemistry A 2015 vol. 3(Issue 4) pp:1703-1708
Publication Date(Web):06 Nov 2014
DOI:10.1039/C4TA05072J
Novel sandwich-like Cr2O3–graphite intercalation composites (Cr2O3–GICs) were synthesized via an intercalation–transformation method. Cr2O3 nanoparticles (NPs) are intercalated between the adjacent carbon layers of graphite and tightly immobilized. The Cr2O3–GICs show promising performance as anode materials for LIBs with a reversible capacity of about 480 mA h g−1 and a relatively low lithium insertion potential. More importantly, the Cr2O3–GICs demonstrate an extremely promising stable cycling performance with over 100% capacity retention after 1000 cycles. Furthermore, the intercalation–transformation method also provides another fabrication method of graphene-based assembled materials.
Co-reporter:Lina Wang, Jingyuan Liu, Servane Haller, Yonggang Wang and Yongyao Xia
Chemical Communications 2015 vol. 51(Issue 32) pp:6996-6999
Publication Date(Web):16 Mar 2015
DOI:10.1039/C5CC00444F
A newly designed hybrid separator composed of a glassy fiber paper and a microporous membrane is effectively integrated into a Li–S battery. Superior cell performance up to 500 cycles is achieved even with commercially available pristine sulfur as cathode material. This fascinating study demonstrates a largely restrained polysulfides shuttle process toward practical Li–S battery application.
Co-reporter:Shouyi Yuan;Ziyang Guo;Lina Wang;Shuang Hu;Yonggang Wang;Yongyao Xia
Advanced Science 2015 Volume 2( Issue 8) pp:
Publication Date(Web):
DOI:10.1002/advs.201500071
Carbon/sulfur composites are attracting extensive attention because of their improved performances for Li–S batteries. However, the achievements are generally based on the low S-content in the composites and the low S-loading on the electrode. Herein, a leaf-like graphene oxide (GO), which includes an inherent carbon nanotube midrib in the GO plane, is synthesized for preparing GO/S composites. Owing to the inherent high conductivity of carbon nanotube midribs and the abundant surface groups of GO for S-immobilization, the composite with an S-content of 60 wt% exhibits ultralong cycling stability over 1000 times with a low capacity decay of 0.033% per cycle and a high rate up to 4C. When the S-content is increased to 75 wt%, the composite still shows a perfect cycling performance over 1000 cycles. Even with the high S-loading of 2.7 mg cm−2 on the electrode and the high S-content of 85 wt%, it still shows a promising cycling performance over 600 cycles.
Co-reporter:Mengyan Hou, Shaoshuai Guo, Jinlong Liu, Jun Yang, Yonggang Wang, Congxiao Wang, Yongyao Xia
Journal of Power Sources 2015 Volume 287() pp:370-376
Publication Date(Web):1 August 2015
DOI:10.1016/j.jpowsour.2015.04.085
•Li-rich layered oxide microspheres composed of nano-size primary particles are prepared by a slurry spray-drying method.•Spray-drying sample show relieved voltage fade compared to the co-precipitated counterpart during the cycling process.•The relieved voltage fade is attributed to a more homogenous TM distribution in spray-drying sample.0.5Li2MnO3·0.5LiMn1/3Ni1/3Co1/3O2 microspheres are prepared by a slurry spray-drying process (SD-LLO) with subsequent heat treatment. SEM images show that the SD-LLO microspheres are composed of nano-size primary particles. These particles are quite different from conventional LLO microspheres, which are composed of micron-scale plate-like primary particles prepared by a co-precipitation method (CP-LLO). The SD-LLO material experiences a smaller voltage drop during cycling than CP-LLO when used as cathode material in lithium-ion batteries. High-resolution transmission electron microscopy (HR-TEM) and energy dispersive spectroscopy (EDS) indicate that the smaller voltage drop of SD-LLO can be attributed to a more homogeneous distribution of transition metals.
Co-reporter:Ke Wang, Mengyan Hou, Shouyi Yuan, Hongchuan Yu, Yonggang Wang, Congxiao Wang, Yongyao Xia
Electrochemistry Communications 2015 Volume 55() pp:6-9
Publication Date(Web):June 2015
DOI:10.1016/j.elecom.2015.03.004
•An additional plateau was observed in the discharge curve of LiMn0.5Fe0.5PO4/C at relative high current rate.•The additional plateau is identified to the Mn3 + reduction reaction.•The capacity of the additional plateau increases with discharge current density increasing.•The additional plateau enables LiMn0.5Fe0.5PO4/C to achieve a large capacity at high current density.LiFe0.5Mn0.5PO4 typically exhibits two pairs of plateaus in charge/discharge curves associated with MnPO4/LiMnPO4 and FePO4/LiFePO4 phase transformation. In this work, an additional plateau was observed at about 3.7 V in the discharge curve at relative high current rates, but not in the charge process. The additional plateau is identified to Mn3 + reduction by capacity analysis, cyclic voltammograms (CV) and galvanostatic intermittent titration technique (GITT) measurement. The capacity of additional plateau increases with the increase of discharge rates. LiFe0.5Mn0.5PO4 discharge mainly proceeds at this plateau at high current rate.
Co-reporter:Jingyuan Liu, Yue Shen, Long Chen, Yonggang Wang, Yongyao Xia
Electrochimica Acta 2015 Volume 156() pp:38-44
Publication Date(Web):20 February 2015
DOI:10.1016/j.electacta.2014.12.117
Nanostructured Li4Ti5O12 is always synthesized under relatively low temperature to prevent crystal growth, however, low-temperature treatment leads to low crystallinity. In this work, we use a chemical vapor deposition strategy to synthesis uniformly carbon layer coated Li4Ti5O12 nanowire. This method allows calcining Li4Ti5O12 nanowire under high temperature to obtain high crystallinity of Li4Ti5O12 without destroying its morphology. The Li4Ti5O12 displays excellent rate capacity. Also, the carbon coated layer could protect the Li4Ti5O12 surface from side reaction with electrolyte. The carbon coated Li4Ti5O12 nanowire shows excellent capacity retention during charge/discharge under elevated temperature of 55 °C due to high crystallinity and reduced side-reaction.
Co-reporter:Jinlong Liu, Mengyan Hou, Jin Yi, Shaoshuai Guo, Congxiao Wang and Yongyao Xia
Energy & Environmental Science 2014 vol. 7(Issue 2) pp:705-714
Publication Date(Web):11 Nov 2013
DOI:10.1039/C3EE41664J
We report the electrochemical properties of layered lithium-rich Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials with various degrees of stacking faults, which are prepared via a facile molten-salt method using a variety of fluxes including KCl, Li2CO3, and LiNO3. The frequency of the stacking faults is highly dependent on the temperature and molten salt type used during the synthesis. A well-crystallized Li1.18Mn0.54Ni0.13Co0.13O2 nanomaterial with a larger amount of stacking faults synthesized at 800 °C for 10 h in an inactive KCl flux delivers a high reversible capacity of ∼310 mA h g−1 at room temperature, while the samples prepared in the chemically active fluxes with a smaller amount of stacking faults show poor electrochemical performance.
Co-reporter:Fei Wang;Jin Yi;Yonggang Wang;Congxiao Wang;Jianqiang Wang;Yongyao Xia
Advanced Energy Materials 2014 Volume 4( Issue 2) pp:
Publication Date(Web):
DOI:10.1002/aenm.201300600
Co-reporter:Yuhang Wang, Yehua Wang, Dingsi Jia, Zheng Peng, Yongyao Xia, and Gengfeng Zheng
Nano Letters 2014 Volume 14(Issue 2) pp:1080-1084
Publication Date(Web):January 29, 2014
DOI:10.1021/nl4047834
We report an all-nanowire based flexible Li-ion battery full cell, using homologous Mn2O3 and LiMn2O4 nanowires for anodes and cathodes, respectively. The same precursors, MnOOH nanowires, are transformed from hydrothermally grown MnO2 nanoflakes and directly attached on Ti foils via reaction with poly(vinyl pyrrolidone). The Mn2O3 anode and LiMn2O4 cathode are subsequently formed by thermal annealing and reaction with lithium salt, respectively. The one-dimensional nanowire structures provide short lithium-ion diffusion path, good charge transport, and volume flexibility for Li+ intercalation/deintercalation, thus leading to good rate capability and cycling performance. As proof-of-concept, the Mn2O3 nanowire anode delivers an initial discharge capacity of 815.9 mA h g–1 at 100 mA g–1 and maintains a capacity of 502.3 mA h g–1 after 100 cycles. The LiMn2O4 nanowire cathodes show a reversible capacity of 94.7 mA h g–1 at 100 mA g–1 and high capacity retention of ∼96% after 100 cycles. Furthermore, a flexible Mn2O3//LiMn2O4 lithium ion full cell is fabricated, with an output voltage of >3 V, low thickness of 0.3 mm, high flexibility, and a specific capacity of 99 mA h g–1 based on the total weight of the cathode material. It also exhibits good cycling stability with a capacity of ∼80 mA h g–1 after 40 charge/discharge cycles.
Co-reporter:Xiaoli Dong;Ziyang Guo;Yanfang Song;Mengyan Hou;Jianqiang Wang;Yonggang Wang;Yongyao Xia
Advanced Functional Materials 2014 Volume 24( Issue 22) pp:3405-3412
Publication Date(Web):
DOI:10.1002/adfm.201304001
Portable and multifunctional electronic devices are developing in the trend of being small, flexible, roll-up, and even wearable, which asks us to develop flexible and micro-sized energy conversion/storage devices. Here, the high performance of a flexible, wire-shaped, and solid-state micro-supercapacitor, which is prepared by twisting a Ni(OH)2-nanowire fiber-electrode and an ordered mesoporous carbon fiber-electrode together with a polymer electrolyte, is demonstrated. This micro-supercapacitor displays a high specific capacitance of 6.67 mF cm–1 (or 35.67 mF cm–2) and a high specific energy density of 0.01 mWh cm–2 (or 2.16 mWh cm–3), which are about 10–100 times higher than previous reports. Furthermore, its capacitance retention is 70% over 10 000 cycles, indicating perfect cyclic ability. Two wire-shaped micro-supercapacitors (0.6 mm in diameter, ≈3 cm in length) in series can successfully operate a red light-emitting-diode, indicating promising practical application. Furthermore, synchrotron radiation X-ray computed microtomography technology is employed to investigate inner structure of the micro-device, confirming its solid-state characteristic. This micro-supercapacitor may bring new design opportunities of device configuration for energy-storage devices in the future wearable electronic area.
Co-reporter:Yanfang Song, Shuang Hu, Xiaoli Dong, Yonggang Wang, Congxiao Wang, Yongyao Xia
Electrochimica Acta 2014 Volume 146() pp:485-494
Publication Date(Web):10 November 2014
DOI:10.1016/j.electacta.2014.09.078
Nitrogen-doped hierarchical mesoporous/microporous carbon (NMMC) was prepared by synthesizing nitrogen-doped mesoporous titanium-carbide/carbon composite, followed by in situ chlorination of carbides. The NMMC possesses a high surface area (1344 m2/g), large pore volumes (0.902 cm3/g), narrowed mesopore-size distributions (centered at 4.6 nm) and micropores drilled on the mesopore walls with the size of 0.70, 0.97 and 1.61 nm. As an electrode material for supercapacitors, the obtained carbon exhibits excellent performance with a reversible specific capacitance as high as 325 F/g in 1 mol/L H2SO4 aqueous electrolytes contributed by the double-layer capacitance and pseudo-capacitance. The high nitrogen content (7.51 at%) plays an important role in the capacitance enhancement of NMMC, due to the faradaic redox reactions. Meanwhile, the micropores drilled on the mesopore walls can increase the specific surface area to provide more sites for charge storage.Nitrogen-doped hierarchical mesoporous/microporous carbon was prepared by synthesizing nitrogen-doped mesoporous titanium-carbide/carbon composite, followed by in situ chlorination of carbides. It possesses a high surface area (1344 m2/g), large pore volumes (0.902 cm3/g), narrowed mesopore-size distributions (centered at 4.6 nm) and micropores drilled on the mesopore walls with the size of 0.70, 0.97 and 1.61 nm, which make the capacitance up to 325 F/g in 1 mol L-1 H2SO4 aqueous electrolytes plus the high nitrogen content of 7.51 at%.
Co-reporter:Ke Wang, Yonggang Wang, Congxiao Wang, Yongyao Xia
Electrochimica Acta 2014 Volume 146() pp:8-14
Publication Date(Web):10 November 2014
DOI:10.1016/j.electacta.2014.09.032
LiMnPO4 nanoplates in a size of 30-70 nm were successfully obtained via a graphene oxide (GO) assisted solvothermal synthesis method. The particle size reduction is ascribed to a preferential nucleation of LiMnPO4 on the GO sheets. The particle size is critically dependent on the added GO content, ranging from 300 nm, 200 nm to 50 nm, when the GO content increase from 5/30, 10/30, to 20/30 mg/cm-3. LiMnPO4 nanoplates were further carbon-coated at 600 °C. Carbon-coated LiMnPO4 (LiMnPO4/C) with a particle size of 30-70 nm displays a specific capacity of 140 mA h g-1 at C/10 and 85 mA h g-1 at 1C rate.
Co-reporter:Mengyan Hou, Jinlong Liu, Shaoshuai Guo, Jun Yang, Congxiao Wang, Yongyao Xia
Electrochemistry Communications 2014 Volume 49() pp:83-87
Publication Date(Web):December 2014
DOI:10.1016/j.elecom.2014.10.009
•A gas–solid reaction between P2O5 and Li-rich layered oxide was employed for surface modification.•A uniform and continuous coating layer presents on the surface of pristine material.•Remarkable improvement in charge/discharge efficiency and rate capability was obtained after surface modification.Rate capability and charge/discharge coulombic efficiency of Li-rich layered oxides was greatly improved by surface modification with P2O5 through a gas–solid reaction. The P2O5 treatment results in forming a uniform nanoscale coating layer of ionically conductive Li3PO4 and spinel-like material on Li-rich layered oxide particles. The resulting material delivers a charge/discharge coulombic efficiency of 90% compared with 81% of the pristine sample during the first cycle. The treated electrode also exhibits improved rate capability with a reversible capacity of 148 mAh g− 1 at 4 C-rate vs. 269 mAh g− 1 at 0.1 C-rate between 2.0 and 4.8 V.
Co-reporter:Jin Yi, Meng-yan Hou, Hong-liang Bao, Cong-xiao Wang, Jian-qiang Wang, Yong-yao Xia
Electrochimica Acta 2014 Volume 133() pp:564-569
Publication Date(Web):1 July 2014
DOI:10.1016/j.electacta.2014.03.164
•A Li2FeSiO4/C nanocomposite is prepared via thermal vapor deposition technology.•The Li2FeSiO4/C nanocomposite is free from impurity and coated with carbon layer.•The Li2FeSiO4/C nanocomposite exhibits good rate capability and cycling stability.•Lithium benzoate serves as both lithium and carbon sources.A Li2FeSiO4/C nanocomposite is prepared via solvothermal method in combination with carbon coating technology. The as-prepared Li2FeSiO4/C nanocomposite is a single phase Li2FeSiO4 with nano-tickness coated carbon layer and connected by the mutual cross-linked carbon conductive matrix. As cathode material for lithium ion battery, the composite delivers a discharge capacity of 154 mAh g−1 at 1 C and exhibits good rate capability with a discharge capacity of 106 mAh g−1 at the rate of 10 C, which is ascribed to the small particle size and enhanced electronic conductivity using carbon coating technology. The as-prepared Li2FeSiO4/C nanocomposite also behaves a good cycling stability with capacity retention of over 100 cycles.
Co-reporter:Long Chen, Wangyu Li, Yonggang Wang, Congxiao Wang and Yongyao Xia
RSC Advances 2014 vol. 4(Issue 48) pp:25369-25373
Publication Date(Web):28 May 2014
DOI:10.1039/C4RA03473B
A polyimide synthesized from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) and ethylene diamine (EDA) was evaluated as a new anode material for sodium ion batteries (SIB). The polyimide delivers a discharge specific capacity of 140 mA h g−1 at an average potential of 2 V vs. Na+/Na with an initial coulombic efficiency of 97.6% and exhibits an excellent cycleability with a capacity retention of 90% over 500 cycles. A full SIB with polyimide anode and Na3V2(PO4)3/C cathode and Na4Fe(CN)6/C cathode was proposed.
Co-reporter:Yanfang Song;Li Li;Dr. Yonggang Wang;Dr. Congxiao Wang; Dr. Zaipin Guo; Dr. Yongyao Xia
ChemPhysChem 2014 Volume 15( Issue 10) pp:2084-2093
Publication Date(Web):
DOI:10.1002/cphc.201402250
Abstract
A new nitrogen-doped ordered mesoporous carbon (N-doped OMC) is synthesized by using an organic–inorganic coassembly method, in which resol is used as the carbon precursor, dicyandiamide as the nitrogen precursor, silicate oligomers as the inorganic precursors, and F127 as the soft template. The N-doped OMC possesses a surface area as high as 1374 m2 g−1 and a large pore size of 7.4 nm. As an electrode material for supercapacitors, the obtained carbon exhibits excellent cycling stability and delivers a reversible specific capacitance as high as 308 F g−1 in 1 mol L−1 H2SO4 aqueous electrolyte, of which 58 % of the capacity is due to pseudo-capacitance. The large specific capacitance is attributed to proper pore size distributions, large surface area, and high nitrogen content.
Co-reporter:Yonggang Wang ;Yongyao Xia
Advanced Materials 2013 Volume 25( Issue 37) pp:5336-5342
Publication Date(Web):
DOI:10.1002/adma.201301932
Abstract
Supercapacitors are currently attracting intensive attention because they can provide energy density by orders of magnitude higher than dielectric capacitors, greater power density, and longer cycling ability than batteries. The main challenge for supercapacitors is to develop them with high energy density that is close to that of a current rechargeable battery, while maintaining their inherent characteristics of high power and long cycling life. Consequently, much research has been devoted to enhance the performance of supercapacitors by either maximizing the specific capacitance and/or increasing the cell voltage. The latest advances in the exploration and development of new supercapacitor systems and related electrode materials are highlighted. Also, the prospects and challenges in practical application are analyzed, aiming to give deep insights into the material science and electrochemical fields.
Co-reporter:Ziyang Guo;Dan Zhou;XiaoLi Dong;Zijie Qiu;Yonggang Wang;Yongyao Xia
Advanced Materials 2013 Volume 25( Issue 39) pp:5668-5672
Publication Date(Web):
DOI:10.1002/adma.201302459
Co-reporter:Guan-Nan Zhu;Long Chen;Yong-Gang Wang;Con-Xiao Wang;Ren-Chao Che
Advanced Functional Materials 2013 Volume 23( Issue 5) pp:640-647
Publication Date(Web):
DOI:10.1002/adfm.201201741
Abstract
Li4Ti5O12 typically shows a flat charge/discharge curve, which usually leads to difficulty in the voltage-based state of charge (SOC) estimation. In this study, a facile quench-assisted solid-state method is used to prepare a highly crystalline binary Li4Ti5O12-Li2Ti3O7 nanocomposite. While Li4Ti5O12 exhibits a sudden voltage rise/drop near the end of its charge/discharge curve, this binary nanocomposite has a tunable sloped voltage profile. The nanocomposite exhibits a unique lamellar morphology consisting of interconnected nanograins of ≈20 nm size with a hierarchical nanoporous structure, contributing to an enhanced rate capability with a capacity of 128 mA h g−1 at a high C-rate of 10 C, and excellent cycling stability.
Co-reporter:Ziyang Guo;Jie Wang;Fei Wang;DanDan Zhou;Yongyao Xia;Yonggang Wang
Advanced Functional Materials 2013 Volume 23( Issue 38) pp:4840-4846
Publication Date(Web):
DOI:10.1002/adfm.201300130
Abstract
Graphene oxide (GO) has recently attracted a great deal of attention because of its heterogeneous chemical and electronic structures and its consequent exhibition of a wide range of potential applications, such as plastic electronics, optical materials, solar cells, and biosensors. However, its insulating nature also limits its application in some electronic and energy storage devices. In order to further widen the applications of GO, it is necessary to keep its inherent characteristics while improving its conductivity. Here, a novel leaf-like GO with a carbon nanotube (CNT) midrib is developed using vapor growth carbon fiber (VGCF) through the conventional Hummers method. The CNT midrib provides a natural electron diffusion path for the leaf-like GO, and therefore, this leaf-like GO with a CNT midrib displays excellent performance when applied in energy storage devices, including Li-O2 batteries, Li-ion batteries, and supercapacitors.
Co-reporter:Dan-Dan Zhou, Yuan-Jin Du, Yan-Fang Song, Yong-Gang Wang, Cong-Xiao Wang and Yong-Yao Xia
Journal of Materials Chemistry A 2013 vol. 1(Issue 4) pp:1192-1200
Publication Date(Web):31 Oct 2012
DOI:10.1039/C2TA00533F
A series of ordered mesoporous/microporous carbon materials with controllable micropore size was prepared from chlorination of ordered mesoporous titanium carbide/carbon composites obtained by an evaporation induced self-assembly approach. The proportion of micropores can be tuned easily by changing the Ti content in the parent TiC/C composites in order to study the effect of micropore content on rate capability and specific capacitance. Under the optimized condition, an optimal mesoporous/microporous carbon with moderate micropores (52.4% in volume) was obtained. It has a high surface area (1698 m2 g−1) and a large pore volume (1.17 cm3 g−1), with the mesopore size centered at 4.4 nm, and micropore sizes of 0.52, 0.76 and 1.35 nm. It exhibits a high capacitance of 132 F g−1 at the current density of 500 mA g−1 and good rate capability with capacitance retention of 79% at a scan rate of 2000 mV s−1vs. 20 mV s−1 in nonaqueous electrolyte, and also shows a good cycling stability with capacitance retention of 84% over 5000 cycles.
Co-reporter:Yue-E Miao, Guan-Nan Zhu, Haoqing Hou, Yong-Yao Xia, Tianxi Liu
Journal of Power Sources 2013 Volume 226() pp:82-86
Publication Date(Web):15 March 2013
DOI:10.1016/j.jpowsour.2012.10.027
Polyimide (PI) nanofiber-based nonwovens have been fabricated via electrospinning for the separators of lithium-ion batteries (LIBs). Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and hot oven tests show that the PI nanofiber-based nonwovens are thermally stable at a high temperature of 500 °C while the commercial Celgard membrane exhibits great shrinkage at 150 °C and even goes melting over 167 °C, indicating a superior thermal stability of PI nanofiber-based nonwovens than that of the Celgard membrane. Moreover, the PI nanofiber-based nonwovens exhibit better wettability for the polar electrolyte compared to the Celgard membrane. The PI nanofiber-based nonwoven separators are also evaluated to have higher capacity, lower resistance and higher rate capability compared to the Celgard membrane separator, which proves that they are ideal candidates for separators of high-performance rechargeable LIBs.Graphical abstractPolyimide (PI) nanofiber-based nonwovens have been fabricated via electrospinning for separators of lithium-ion batteries (LIBs). The electrospun PI nanofiber-based nonwovens exhibit superior thermal stability and better wettability for the liquid electrolyte. They are also evaluated to have higher capacity, lower resistance and higher rate capability compared to the commercial Celgard membrane separator, making them ideal candidates for separators of high-performance rechargeable LIBs.Highlights► Polyimide (PI) nanofiber-based nonwovens have been fabricated via electrospinning for separators of LIBs. ► Electrospun PI nanofiber nonwovens show superior thermal stability than that of the commercial Celgard membrane. ► Compared to the Celgard membrane, PI nanofiber nonwovens exhibit better wettability toward electrolyte. ► The electrospun PI nanofiber nonwoven separators present high-performance battery properties.
Co-reporter:Chunming Zhang, Yaoyao Zhang, Jin Wang, Dan Wang, Dannong He, Yongyao Xia
Journal of Power Sources 2013 Volume 236() pp:118-125
Publication Date(Web):15 August 2013
DOI:10.1016/j.jpowsour.2013.01.135
Li4Ti5O12 was synthesized by a modified and facile sol–gel method with ethylene diamine tetraacetic acid (EDTA) and citric acid (CA) as a bi-components chelating agent. The raw precursor and powders further calcined at various temperatures and holding time were characterized by XRD, FT-IR, TG, BET and SEM. Nano-scale Li4Ti5O12 oxides, with a high phase purity and good stoichiometry, can be obtained at a calcination temperature of 750 °C and higher. The Li4Ti5O12 nanoparticle shows a network morphology with high dispersion, which reached a capacity of 164 and 108 mAh g−1 at 1C and 10C discharge rate, respectively. The result of the cycling performance shows a high capacity maintenance ratio of 97% at 1C and 25 °C after 1000 cycles. Electrochemical lithium intercalation/extraction performance is also evaluated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) at room temperature.Highlights► An enhanced chelating agent scheme for uniformly distributed products. ► Ethylene diamine tetraacetic acid (EDTA) and citric acid (CA) as the bi-components chelating agent. ► The bi-components chelating agent to improve the particles dispersion and decrease the particle size. ► Nano-scale Li4Ti5O12 oxides show superior electrochemical performance and cycle life. ► The bi-components chelating agent scheme is robust and efficient.
Co-reporter:Yonggang Wang, Dan Zhao, Renchao Che, Yongyao Xia
Journal of Power Sources 2013 Volume 236() pp:230-237
Publication Date(Web):15 August 2013
DOI:10.1016/j.jpowsour.2013.02.071
Co-reporter:Yuanjin Du, Guannan Zhu, Ke Wang, Yonggang Wang, Congxiao Wang, Yongyao Xia
Electrochemistry Communications 2013 Volume 36() pp:107-110
Publication Date(Web):November 2013
DOI:10.1016/j.elecom.2013.09.019
•A nano-sized Si/graphene composite was prepared by magnesium thermal reducing of the in-situ generated SiO2 on graphene sheets.•The Si/graphene composite delivers large reversible capacity with excellent cycling stability.•The graphene and nanospaces between Si nanoparticles could accommodate volume expansion during lithium insertion and extraction.A nanosized Si/graphene composite was prepared by magnesium thermal reduction of the in-situ generated SiO2 particles on graphene sheets, in which about 5 nm-silicon nanoparticles were homogeneously loaded on graphene sheets. The unique structure can not only accommodate the large volume changes, but also maintain electronic conductivity during Li-ion insertion/extraction. The composite delivers an initial reversible capacity of 1750 mAh/g at a current rate of 100 mA/g and exhibits an excellent cycling stability with a capacity of 1374 mAh/g over 120 cycles.
Co-reporter:Jin Yi, Congxiao Wang, Yongyao Xia
Electrochemistry Communications 2013 Volume 33() pp:115-118
Publication Date(Web):August 2013
DOI:10.1016/j.elecom.2013.04.015
•The thermal stability is critically dependent on its oxidation/reduction activity.•The difference in thermal stability is small for LTO with different particle size.•No big difference is seen in thermal stability of LFP with different particle size.•The nano-sized LCO exhibits less thermal stability than the micro-sized LCO.The thermal stabilities of several electrode materials of Li-ion batteries (Li4Ti5O12, LiFePO4, and LiCoO2) with different particle size (micro and nano-scale) under lithiated or delithiated state have been investigated using differential scanning calorimetry. The thermal stability (exothermic peak temperature and heat flow) is critically dependent on its oxidation/reduction activity. Both lithiated Li4Ti5O12 and delithiated LiFePO4 show slight differences in thermal stability between the nano- and micro-scale, while delithiated nano-sized LiCoO2 exhibits lower exothermic peak temperature and larger thermal runaway than the micro-sized LiCoO2.
Co-reporter:Jin Yi, Julian Key, Fei Wang, Yonggang Wang, Congxiao Wang, Yongyao Xia
Electrochimica Acta 2013 Volume 106() pp:534-540
Publication Date(Web):1 September 2013
DOI:10.1016/j.electacta.2013.05.035
•The graphite-anchored lithium vanadium oxide was prepared by the in situ method.•The effects of synthesis conditions on electrochemical performance were studied.•This material delivers better electrochemical performance and thermal stability.•Carbon-coating technology was applied to enhance the electrochemical performance.Graphite-anchored lithium vanadium oxide (Li1.1V0.9O2) has been synthesized via a “one-pot” in situ method. The effects of the synthesis conditions, such as the ratio of reaction components and calcination temperature, on the electrochemical performance are systematically investigated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), galvanostatic discharge/charge tests and differential scanning calorimetry (DSC). Compared with the simple mixture of graphite and lithium vanadium oxide, the graphite-anchored lithium vanadium oxide delivers an enhanced reversible capacity, rate capability and cyclic stability. It also shows better thermal stability.
Co-reporter:Dan Zhao, Yun-long Feng, Yong-gang Wang, Yong-yao Xia
Electrochimica Acta 2013 Volume 88() pp:632-638
Publication Date(Web):15 January 2013
DOI:10.1016/j.electacta.2012.10.101
In the present work, various LiFePO4/carbon composites were prepared through a facile solvothermal route followed by heat treatment. These as-prepared LiFePO4/carbon composites, including LiFePO4/acetylene black (95:5 wt.%), LiFePO4/carbon nanotube (95:5 wt.%) and LiFePO4/graphene (95:5 wt.%), were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Their electrochemical performances were also investigated and compared in detail. The achieved results indicate that both particle-size and electrochemical performance of LiFePO4 much depend on the carbon supporter. When acetylene black and carbon nanotube were used as carbon supporter, the prepared LiFePO4 particles were agglomerate together to form large-size second particles which cannot well connect with carbon supporter. In the LiFePO4/graphene composite, ∼50 nm LiFePO4 particles uniformly loaded on the two-dimensional carbon supporter, and thus display much better rate ability. This result suggests that graphene should be a promising carbon supporter for LiFePO4.
Co-reporter:Guan-nan Zhu, Yuan-jin Du, Yong-gang Wang, Ai-shui Yu, Yong-yao Xia
Journal of Electroanalytical Chemistry 2013 Volume 688() pp:86-92
Publication Date(Web):1 January 2013
DOI:10.1016/j.jelechem.2012.07.035
In this study, we report a carbon-coated Li4Ti5O12/hard carbon composite as an anode for Li-ion batteries. The composite anode provides a clear edge in state-of-charge (SOC) estimation of Li-ion batteries and thus enables efficient energy management and health assessment. The shape of the charge/discharge curve for Li4Ti5O12 (LTO) is significantly modified by the addition of the hard carbon in an optimised amount to present a smoothly sloped voltage profile in the voltage window between 0.01 and 1.5 V. This voltage range is highly effective in avoiding overcharging of a type of Li-ion batteries, where cell voltages remain constant over a large SOC region. Compared with the pristine LTO anode charged/discharged between 3 and 0.01 V, the composite anode, in addition to showing an improved specific capacity and cycling stability, demonstrates a strong enhancement in the rate capability; at a rate as high as 20 C, a capacity of 160 mAh/g is still retained, which has been proven to arise from a dual improvement in the electronic conductivity by the hard carbon through mixing and the soft carbon via carbon coating. The advantages in SOC prediction and the excellent rate capability are expected to greatly promote its practical application.Highlights► A carbon-coated Li4Ti5O12/hard carbon composite. ► An advantage in real-time state of charge (SOC) estimation of Li-ion batteries. ► Excellence in rate capability and cycling stability.
Co-reporter:Ziyang Guo, Xiaoli Dong, Dandan Zhou, Yuanjin Du, Yonggang Wang and Yongyao Xia
RSC Advances 2013 vol. 3(Issue 10) pp:3352-3358
Publication Date(Web):21 Dec 2012
DOI:10.1039/C2RA23336C
TiO2(B) nanofiber bundles have been successfully synthesized by a facile method. Compared with conventional nanosized/nanostructured TiO2(B), the as-prepared sample displays a much lower surface area. It was demonstrated that the as-prepared TiO2(B) displays both good rate ability and long cycle life for Li-storage in a non-aqueous electrolyte. The TiO2(B)-based electrode can still maintain ∼80% of its initial reversible capacity over 2000 cycles. In addition, the as-prepared TiO2 was coupled with LiFePO4 to form a rechargeable Li-ion battery, which shows good reversibility with a sloping voltage from 1.5 to 2.3 V, high power performance as well as a promising cycle life. Finally, the charge storage ability of the TiO2(B)/LiFePO4 battery was compared with that of a Li4Ti5O12/LiFePO4 battery. The inherent slope potential profile of the TiO2(B) anode effectively widens the charge storage voltage window of the TiO2(B)/LiFePO4 battery, and thus makes the TiO2(B)/LiFePO4 battery exhibit a better charge storage ability.
Co-reporter:Yanfang Song, Dandan Zhou, Yonggang Wang, Congxiao Wang and Yongyao Xia
New Journal of Chemistry 2013 vol. 37(Issue 6) pp:1768-1775
Publication Date(Web):03 Apr 2013
DOI:10.1039/C3NJ00261F
Nitrogen-containing mesoporous carbons (NMCs) were prepared from quinoline-polymerized pitch using mesoporous silica as a template. The effects of the ratio of quinoline-polymerized pitch/silica template and carbonization temperature on the capacitive performance of NMCs were extensively studied. The NMC synthesized at a pitch–silica template ratio of 1.5 and carbonized at 750 °C has a high surface area of 1000 m2 g−1 and a high nitrogen content of 5.43%. The unique pore structure and nitrogen functionalities enable the carbon to exhibit a high capacitance of up to 290 F g−1 in 1 mol L−1 H2SO4 aqueous electrolytes.
Co-reporter:Guan-Nan Zhu, Yong-Gang Wang and Yong-Yao Xia
Energy & Environmental Science 2012 vol. 5(Issue 5) pp:6652-6667
Publication Date(Web):23 Feb 2012
DOI:10.1039/C2EE03410G
Li-ion batteries are one of the most promising electrochemical power sources to be widely used in portable electronics, electric vehicles, and stationary energy storage systems. Ti-based materials have been intensively investigated as important anodes for Li-ion batteries due to their high safety and excellent cycling stability. The present work reviews the latest advances in the exploration and development of Ti-based compounds, such as Li4Ti5O12, Li2Ti3O7, TiO2-B and H2Ti3O7, as high performance anode materials for Li-ion batteries. The relationship between the preparation, composition, structure, morphology and electrochemical performance are summarized and analyzed. Further, the related advancements and challenges in practical energy applications are discussed.
Co-reporter:Yonggang Wang;Jin Yi ;Yongyao Xia
Advanced Energy Materials 2012 Volume 2( Issue 7) pp:830-840
Publication Date(Web):
DOI:10.1002/aenm.201200065
Abstract
Building a low-carbon society supported by sustainable energy is a worldwide topic. The aqueous lithium-ion battery (LIB) has been demonstrated to be one of the most promising stationary power sources for sustainable energies such as wind and solar power. The aqueous LIB may solve both the safety problem associated with the lithium-ion batteries which use highly toxic and flammable organic solvents, and the poor cycling life associated with commercialized aqueous rechargeable batteries including lead-acid and nickel-metal-hydride systems. During the past decades, many efforts have been made to improve the performance of the aqueous lithium-ion battery. The present work reviews the latest advances in the exploration and development of battery systems and relative materials. Also the main approaches, achievements, and challenges in this field are briefly commented on and discussed.
Co-reporter:Yonggang Wang;Zhensheng Hong;Mingdeng Wei;Yongyao Xia
Advanced Functional Materials 2012 Volume 22( Issue 24) pp:5185-5193
Publication Date(Web):
DOI:10.1002/adfm.201200766
Abstract
Layered H2Ti6O13-nanowires are prepared using a facile hydrothermal method and their Li-storage behavior is investigated in non-aqueous electrolyte. The achieved results demonstrate the pseudocapacitive characteristic of Li-storage in the layered H2Ti6O13-nanowires, which is because of the typical nanosize and expanded interlayer space. The as-prepared H2Ti6O13-nanowires have a high capacitance of 828 F g−1 within the potential window from 2.0 to 1.0 V (vs. Li/Li+). An asymmetric supercapacitor with high energy density is developed successfully using H2Ti6O13-nanowires as a negative electrode and ordered mesoporous carbon (CMK-3) as a positive electrode in organic electrolyte. The asymmetric supercapacitor can be cycled reversibly in the voltage range of 1 to 3.5 V and exhibits maximum energy density of 90 Wh kg−1, which is calculated based on the mass of electrode active materials. This achieved energy density is much higher than previous reports. Additionally, H2Ti6O13//CMK-3 asymmetric supercapacitor displays the highest average power density of 11 000 W kg−1. These results indicate that the H2Ti6O13//CMK-3 asymmetric supercapacitor should be a promising device for fast energy storage.
Co-reporter:Jinlong Liu, Long Chen, Mengyan Hou, Fei Wang, Renchao Che and Yongyao Xia
Journal of Materials Chemistry A 2012 vol. 22(Issue 48) pp:25380-25387
Publication Date(Web):12 Oct 2012
DOI:10.1039/C2JM35026B
Well-crystallized and high-performance xLi2MnO3·(1 − x)LiMn1/3Ni1/3Co1/3O2 (x = 0.3, 0.5, and 0.7) structurally integrated nanomaterials are prepared by a facile molten-salt strategy. The effects of heat-treatment temperature, time, and the molar ratio of KCl flux to reaction precursor on the particle size as well as the electrochemical properties are explored. Our results demonstrate that a 0.5Li2MnO3·0.5LiMn1/3Ni1/3Co1/3O2 electrode delivers a high reversible capacity of 313 mA h g−1 with significant enhancement in the initial coulombic efficiency (87%) at room temperature, exhibits superior rate capability and shows improved electrochemical properties over a wide temperature range, in particular at low temperature.
Co-reporter:Xiao-Ming Wang, Dan-Dan Zhou, Qing-Qing Zou and Yong-Yao Xia
Journal of Materials Chemistry A 2012 vol. 22(Issue 30) pp:15418-15426
Publication Date(Web):01 Jun 2012
DOI:10.1039/C2JM32547K
The application of anionic stabilizers is of great importance in the synthesis of supported metal nanoparticles with small and uniform size and high dispersion. Herein, we extensively studied the influence of four congeneric anionic stabilizers on the morphology of carbon-supported Pd nanoparticles, and evaluated the efficacy of anionic stabilizers by testing the catalytic property of supported Pd nanoparticles toward formic acid electrooxidation. The results reveal that the morphology of carbon-supported Pd nanoparticles strongly depends on the steric hindrance and coordination effects of the anionic stabilizers. To be more specific, (1) large steric hindrance of anionic stabilizers is beneficial to form a small and uniform Pd particle size; (2) coordination compound formation between Pd ions and stabilizer molecules facilitates the dispersion of Pd nanoparticles on carbon black; and (3) both large steric hindrance and coordination compound formation can decrease the deposition of Pd nanoparticles in the micropores of carbon black. This work provides a reference point for future work aspiring to develop even better anionic stabilizers for the synthesis of supported metal nanoparticles.
Co-reporter:Qing-Qing Zou, Guan-Nan Zhu, Yong-Yao Xia
Journal of Power Sources 2012 Volume 206() pp:222-229
Publication Date(Web):15 May 2012
DOI:10.1016/j.jpowsour.2011.12.050
LiFe0.2Mn0.8PO4 has been prepared by a solid state reaction process in combination with a ball-milling with carbon black and sucrose as carbon sources. The effects of the ratio of carbon precursors, the total carbon content, and ball-milling time on the physico-chemical and electrochemical properties of C-LiFe0.2Mn0.8PO4 are extensively studied. Under the optimal condition, the as-prepared Li Fe0.2Mn0.8PO4 gives a capacity of 150 mAh g−1 at 1/20C and 110 mAh g−1 at 1C. A novel lithium-ion battery consisting of LiFe0.2Mn0.8PO4 cathode, Li4Ti5O12 anode delivers a capacity of 70 mAh g−1 and a specific energy of 170 Wh kg−1 with an output voltage of 2.45 V based on the total weight of both active electrode materials. The cell also exhibits an excellent cycling stability with a capacity retention of 92% over 200 charge/discharge cycles.Highlights► LiFe0.2Mn0.8PO4 has been prepared by a solid state reaction process. ► The effects of carbon precursors, total carbon content, and ball-milling time are studied. ► A novel lithium-ion battery consisting of LiFe0.2Mn0.8PO4 and Li4Ti5O12 was developed. ► The cell also exhibits an excellent cycling stability.
Co-reporter:Ziyang Guo, Guannan Zhu, Zijie Qiu, Yonggang Wang, Yongyao Xia
Electrochemistry Communications 2012 Volume 25() pp:26-29
Publication Date(Web):November 2012
DOI:10.1016/j.elecom.2012.09.022
Li–O2 batteries using the ionic-liquid based electrolyte consisting of 1-ethyl-3-methylimidazolium tetrafluoroborate and lithium bis((trifluoromethyl)sulfonyl)imide were investigated with carbon catalyst (Super P), α-MnO2 nanorods/carbon composite catalyst (Super P + α-MnO2) and γ-MnOOH nanorods/carbon composite catalyst (Super P + γ-MnOOH). It is demonstrated that γ-MnOOH nanorods display higher electrocatalytic performance for O2 reduction in ionic-liquid based electrolyte, compared with that of Super P and α-MnO2 nanorods. The Li–O2 battery using γ-MnOOH nanorods/carbon composite as catalyst displays a high discharge capacity of 9400 mAh/g at a low current density of 50 mA/g and can be stably cycled 100 times with a current density of 200 mA/g.Highlights► Introduce a Li-O2 battery using γ-MnOOH nanorods as catalyst in ionic-liquid based electrolyte. ► Electrocatalytic performance of γ-MnOOH is higher than that of Super P and α-MnO2. ► The Li-O2 battery using γ-MnOOH as catalyst displays a high discharge capacity of 9400 mAh/g. ► The Li-O2 battery using γ-MnOOH as catalyst can be cycled 100 times.
Co-reporter:Jie Wang, Jin-Long Liu, Yong-Gang Wang, Cong-Xiao Wang, Yong-Yao Xia
Electrochimica Acta 2012 Volume 74() pp:1-7
Publication Date(Web):15 July 2012
DOI:10.1016/j.electacta.2012.03.099
A series of pitch modified hard carbons was prepared using coal-tar pitch and phenolic resin as carbon precursors. The effects of the amount of the soft carbon from pitch precursor, varying from 0 wt% to 40 wt%, and heat-treatment temperature in the range from 900 °C to 1800 °C, on their electrochemical performance were systemically studied, including the reversible capacity, coulombic efficiency in the first cycle, the rate capability and cycling stability. Under the optimal condition, the carbon material obtained at 1200 °C with 30 wt% soft carbon as negative material for lithium-ion batteries exhibits a reversible capacity of about 290 mAh g−1 at a constant current density of 0.5 mA cm−2 with excellent rate capability and cycling stability.
Co-reporter:Guan-Nan Zhu, Hai-Jing Liu, Ji-Hua Zhuang, Cong-Xiao Wang, Yong-Gang Wang and Yong-Yao Xia
Energy & Environmental Science 2011 vol. 4(Issue 10) pp:4016-4022
Publication Date(Web):08 Aug 2011
DOI:10.1039/C1EE01680F
In this study, we report a facile process for preparing a carbon-coated nanosized Li4Ti5O12 nanoporous micro-sphere (CN-LTO-NMS) by a carbon pre-coating process combined with the spray drying method. The obtained material consists of a micron-size secondary sphere (10–20 μm) accumulated by carbon-coated nanosized primary particles (∼200 nm). The nanosized primary particles and nano-thickness carbon layer uniformly coated over the particles as well as the interconnected nanopores greatly improve its rate capability. As a consequence, the resulting sample delivers a reversible capacity of 160 mAhg−1 at 0.2 C, and shows remarkable rate capability by maintaining 79% of the capacity at 20 C (vs. 0.2 C), as well as excellent cycling stability with a capacity retention of 95% after 1000 cycles at 1 C rate (vs. 0.2 C).
Co-reporter:Hai-Jing Liu;Jie Wang;Cong-Xiao Wang
Advanced Energy Materials 2011 Volume 1( Issue 6) pp:1101-1108
Publication Date(Web):
DOI:10.1002/aenm.201100255
Abstract
Novel ordered hierarchical mesoporous/microporous carbon (OHMMC) derived from mesoporous titanium-carbide/carbon composites was prepared for the first time by synthesizing ordered mesoporous nanocrystalline titanium-carbide/carbon composites, followed by chlorination of titanium carbides. The mesostructure and microstructure can be conveniently tuned by controlling the TiC contents of mesoporous TiC/C composite precursor, and chlorination temperature. By optimal condition, the OHMMC has a high surface area (1917 m2g−1), large pore volumes (1.24 cm3g−1), narrow mesopore-size distributions (centered at about 3 nm), and micropore size of 0.69 and 1.25 nm, and shows a great potential as electrode for supercapacitor applications: it exhibits a high capacitance of 146 Fg−1 in noaqueous electrolyte and excellent rate capability. The ordered mesoporous channel pores are favorable for retention and immersion of the electrolyte, providing a more favorable path for electrolyte penetration and transportation to achieve promising rate capability performance. Meanwhile, the micropores drilled on the mesopore-walls can increase the specific surface area to provide more sites for charge storage.
Co-reporter:Huanming Xiong, Weizhi Shen, Binkun Guo, Shouhang Bo, Wangjun Cui, Liquan Chen, Hong Li and Yongyao Xia
Journal of Materials Chemistry A 2011 vol. 21(Issue 9) pp:2845-2847
Publication Date(Web):24 Jan 2011
DOI:10.1039/C0JM03558K
A series of PEG–SnO2 nanocomposites has been investigated as anode materials for lithium batteries. They exhibited an unexpectedly high lithium storage over the theoretical capacity of SnO2. The origin of such extra capacity cannot be interpreted by the conventional lithium storage mechanisms of anode materials.
Co-reporter:Guan-Nan Zhu, Cong-Xiao Wang, Yong-Yao Xia
Journal of Power Sources 2011 Volume 196(Issue 5) pp:2848-2853
Publication Date(Web):1 March 2011
DOI:10.1016/j.jpowsour.2010.07.023
The thermally-induced structural transformation of layered hydrogen trititanate (H2Ti3O7) to TiO2(B) has been systematically studied by means of in situ X-ray diffraction (XRD) over a wide temperature range from 170 to 450 °C. Our data indicate a structural transition realized via continuous loss of interlayer water, which results in a series of non-stoichiometric hydrogen titanate compounds (3TiO2·δH2O). Electrochemical analysis of hydrogen titanates for lithium-ion intercalation shows that reversible specific capacity increases as calcination temperature increases, whereas cycling stability decreases during the continuous dehydration process.
Co-reporter:Jin-long Liu, Wang-jun Cui, Cong-xiao Wang, Yong-yao Xia
Electrochemistry Communications 2011 Volume 13(Issue 3) pp:269-271
Publication Date(Web):March 2011
DOI:10.1016/j.elecom.2010.12.031
The electrochemical properties of cobalt chloride was investigated in 1 M LiPF6-ethylene carbonate (EC)/diethyl carbonate (DMC)/ethyl methyl carbonate (EMC) (1:1:1 by volume) electrolyte within 3.0 V to 0 V. We for the first time found that CoCl2 material can electrochemically reversibly react with lithium via a conversion reaction, and delivers a reversible capacity of ca. 400 mA h g−1 at the 1 C rate at room temperature. This finding proves that conversion reactions in lithium-ion batteries can be expanded to transition-metal chlorides.
Co-reporter:Xiao-Ming Wang, Jie Wang, Qing-Qing Zou, Yong-Yao Xia
Electrochimica Acta 2011 Volume 56(Issue 3) pp:1646-1651
Publication Date(Web):1 January 2011
DOI:10.1016/j.electacta.2010.08.003
In this article, Pd nanoparticles supported on carbon-modified rutile TiO2 (CMRT) as a highly efficient catalyst for formic acid electrooxidation were investigated. Pd/CMRT catalyst was synthesized by using liquid phase reduction method in which Pd nanoparticles was loaded on the surface of CMRT obtained through a chemical vapor deposition (CVD) process. Pd/CMRT shows three times the catalytic activity of Pd/C, as well as better catalytic stability towards formic acid electrooxidation. The enhanced catalytic property of Pd/CMRT mainly arises from the improved electronic conductivity of carbon-modified rutile TiO2, the dilated lattice constant of Pd nanoparticles, an increasing of surface steps and kinks in the microstructure of Pd nanoparticles and slightly better tolerance to the adsorption of poisonous intermediates.
Co-reporter:Ping He, Jin-Long Liu, Wang-Jun Cui, Jia-Yan Luo, Yong-Yao Xia
Electrochimica Acta 2011 Volume 56(Issue 5) pp:2351-2357
Publication Date(Web):1 February 2011
DOI:10.1016/j.electacta.2010.11.027
The capacity loss rate of LiFePO4 in aqueous electrolyte was found to be much faster than it in organic electrolyte. The cycling stability in aqueous electrolyte with various dissolved oxygen content and pH value was extensively studied by cyclic voltammetry. It was found that both high OH− and dissolve O2 content can accelerate the cycling fading of LiFePO4. It has been proved that the capacity fading of LiFePO4 is due to not only chemical instability but also electrochemical instability. Mössbauer spectroscopy demonstrated that the Fe(III)-containing species was formed in the active materials arisen from the irreversible side reaction. The carbon-coated LiFePO4 prepared by chemical vapor decomposition method shows significantly improvement in cycling stability. The carbon coating technology provides an effective approach to enhance cycling performance in aqueous electrolyte as well as proof of proposed fading mechanism.
Co-reporter:Jin-Long Liu, Jie Wang, Yong-Yao Xia
Electrochimica Acta 2011 Volume 56(Issue 21) pp:7392-7396
Publication Date(Web):30 August 2011
DOI:10.1016/j.electacta.2011.05.080
We reported a new type of rechargeable lithium-ion battery consisting of a structurally integrated 0.4Li2MnO3·0.6LiMnNi0.4Co0.2O2 cathode and a hard carbon anode. The drawback of the high irreversible capacity loss of both electrodes, occurring at the first charge/discharge process, can be counterbalanced each other. The battery shows good reversibility with a sloping voltage from 1.5 V to 4.5 V and delivers a capacity of 105 mA h g−1 and a specific energy of 315 W h kg−1 based on the total weight of the both active electrode materials.Highlights► A new type of battery with 0.4Li2MnO3 0.6LiMn0.4Ni0.4Co0.2O2 and hard carbon was proposed. ► The irreversible capacity encountered at both electrodes, can be counterbalanced each other. ► The battery delivers capacities of 105 mAh g-1 and specific energies of 315 Wh kg–1.
Co-reporter:Xiao-Ming Wang, Ming-E Wang, Dan-Dan Zhou and Yong-Yao Xia
Physical Chemistry Chemical Physics 2011 vol. 13(Issue 30) pp:13594-13597
Publication Date(Web):24 Jun 2011
DOI:10.1039/C1CP21680E
The pathway of formic acid electrooxidation strongly depends on the amount of three neighbouring Pt or Pd atoms in the surface of Pd- or Pt-based catalysts. Here, Pt decorated Pd/C nanoparticles (the optimal atomic ratio, Pd:Pt = 20:1) were designed and then synthesized through a facile galvanic replacement reaction where the amount of three neighbouring Pt or Pd atoms markedly decreased. As a result, discontinuous Pd and Pt atoms suppressed CO formation and exhibited unprecedented catalytic activity and stability toward formic acid electrooxidation while the cost was almost the same as that of Pd/C.
Co-reporter:Xiao Gu ; Jin-long Liu ; Ji-hui Yang ; Hong-jun Xiang ; Xin-gao Gong
The Journal of Physical Chemistry C 2011 Volume 115(Issue 25) pp:12672-12676
Publication Date(Web):June 3, 2011
DOI:10.1021/jp202846p
The electrochemical stability of layer-structured LiCoO2 in a Li+-containing aqueous electrolyte solution is critically dependent on the solution pH. The capacity fades upon cycling in electrolyte solutions below pH 11. We have investigated the detailed atomic-scale mechanism of the failure of LiCoO2 in the presence of H+ using first-principles methods. In layer-structured LiCoO2, lithium ion diffusion paths are two-dimensional channels between the cobalt–oxygen layers. However, in an aqueous electrolyte solution containing a considerable number of H+ ions, H+ will be transported into the cathodes to replace the Li+ ions. Our calculations show that once the H+ ions are intercalated into the LixCoO2 cathode, they may covalently bond to the oxygen ions, thereby decreasing the capacity of the cathodes. We have also found that such hydrogen intercalation increases barriers to the diffusion of lithium ions. Therefore, the channels would be blocked after a sufficient number of H+ ions have intercalated, typically after a few cycles.
Co-reporter:Hai-Jing Liu, Xiao-Ming Wang, Wang-Jun Cui, Yu-Qian Dou, Dong-Yuan Zhao and Yong-Yao Xia
Journal of Materials Chemistry A 2010 vol. 20(Issue 20) pp:4223-4230
Publication Date(Web):08 Apr 2010
DOI:10.1039/B925776D
Mesoporous carbons with large uniform pore sizes and high surface areas are of great interest due to their potential applications in electrochemical double layer capacitors (EDLCs), hydrogen storage, separation and catalysis. Here, we report a facile synthesis approach to highly ordered mesoporous carbon nanofiber arrays (MCNAs) by combining surfactant-templating self-assembly of organic resols with a natural crab shell hard-templating process. The obtained materials consist of a mesoporous carbon nanofiber (70 nm in mean diameter and 11 nm in mesopore), an interspacing void of 70 nm between nanofibers, and 1 micrometre of pores between nanofiber arrays. The unique structure (ordered mesopores, macroporous voids and partially graphitic framework) provides a more favorable path for electrolyte penetration and transportation, good electronic conductivity, as well as possess a large specific surface area (1270 m2 g−1) and more vacancies or defects in a graphite plane, which facilitate uniform distribution of metal nanoparticles and a synergistic effect between the nanoparticles and MCNAs, and give rise to promising electrocatalytic activity as a supporting medium for Pt in direct methanol fuel cells. The resultant materials also have excellent capacitive performance for supercapacitor application.
Co-reporter:Liang Cheng, Jing Yan, Guan-Nan Zhu, Jia-Yan Luo, Cong-Xiao Wang and Yong-Yao Xia
Journal of Materials Chemistry A 2010 vol. 20(Issue 3) pp:595-602
Publication Date(Web):20 Nov 2009
DOI:10.1039/B914604K
A simple approach is proposed to synthesize nanostructured Li4Ti5O12 spinel materials with different morphologies (nanorods, hollow spheres and nanoparticles), in which the TiO2 precursor is first coated with a conductive carbon layer by the chemical vapour decomposition (CVD) method, followed by a solid-state reaction with lithium salt. The Li4Ti5O12 obtained was characterised by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), as well as galvanostatic measurements. The results indicate that, by employing the carbon pre-coating process, the carbon-coated nanostructured Li4Ti5O12 can maintain the initial morphologies of the TiO2 precursors and also show significant improvement in the rate capability for lithium-ion intercalation due to both good electronic conductivity and the short lithium-ion diffusion path.
Co-reporter:Xiao-Ming Wang, Yong-Yao Xia
Electrochimica Acta 2010 Volume 55(Issue 3) pp:851-856
Publication Date(Web):1 January 2010
DOI:10.1016/j.electacta.2009.09.037
The influence of the crystal structure of TiO2 support material on Pd catalyst-mediated formic acid electrooxidation was investigated. Pd/TiO2 catalysts were synthesized by loading Pd on TiO2 with different crystal structures obtained by calcinations at different temperatures. Electrochemical tests showed that TiO2 with the rutile structure improved the catalytic activity of Pd nanoparticles toward formic acid electrooxidation. Physicochemical and electrochemical characterizations revealed that the enhancement of Pd/TiO2 (rutile) catalytic activity arose from uniform dispersion of Pd nanoparticles, an increase in surface-active sites, and good tolerance to the adsorption of poisonous intermediates (such as COad, COOHad and so on).
Co-reporter:Xin-hui Yang
Journal of Solid State Electrochemistry 2010 Volume 14( Issue 1) pp:
Publication Date(Web):2010 January
DOI:10.1007/s10008-009-0791-8
The influences of oxygen pressure on the performance of a lithium/oxygen battery using non-aqueous electrolyte were investigated in this paper. Oxygen pressures were adjusted from 1 to 10 atm. It was found that, at all examined discharge rates from 0.1 to 1.0 mA cm−2, the discharge capacity increased with the increasing of oxygen pressure, especially at a high discharge rate. The morphology of the discharge product was found to relate to discharge rate and oxygen pressure by scanning electron microscopy observation.
Co-reporter:Wang-jun Cui, Feng Li, Hai-jing Liu, Cong-xiao Wang and Yong-yao Xia
Journal of Materials Chemistry A 2009 vol. 19(Issue 39) pp:7202-7207
Publication Date(Web):20 Aug 2009
DOI:10.1039/B909769D
A core–shell-structure carbon-coated nanoscale Cu6Sn5 is prepared by using an in situpolymerization method integrated with a surface modification technology. The composite combines the merits of intermetallic compounds and nano-sized anode materials, and exhibits an excellent cycling stability. The improvement in the cycling stability could be attributed to the fact that the well-coated carbon layer can effectively prevent the encapsulated low melting point alloy from out-flowing in a high-temperature treatment process, as well as preventing aggregation and pulverization of nano-sized Cu6Sn5 alloy particles during charge/discharge cycling.
Co-reporter:Hai-Jing Liu, Wang-Jun Cui, Ling-Hua Jin, Cong-Xiao Wang and Yong-Yao Xia
Journal of Materials Chemistry A 2009 vol. 19(Issue 22) pp:3661-3667
Publication Date(Web):16 Apr 2009
DOI:10.1039/B819820A
A two-step template approach was demonstrated for preparation of the three-dimensional ordered mesoporous carbon sphere arrays. The ordered macroporous silica skeleton was formed from silicon alkoxide precursor templating around polystyrene (latex) spheres, and removal of the polystyrene spheres. These preforms as hard templates were infiltrated with a solution mixture of amphiphilic triblock copolymer PEO-PPO-PEO and soluble resol. By combining evaporation-induced surfactant-templating organic resol self-assembly with thermosetting, carbonization and hydrofluoric acid extraction of silica, the obtained mesoporous carbon has a pore size of 10.4 nm, interconnected window size of about 60 nm, surface area of 601 m2/g and pore volume of 1.70 cm3/g. The electrochemical properties as an electrode material for supercapacitor applications were investigated in nonaqueous electrolyte. They show rectangular-shaped cyclic voltammetry curves over a wide range of scan rates even up to 200 mV/s between 0 and 3 V, and deliver a large capacitance of 14 µF/cm2 (84 F/g), and good cycling stability with capacitance retention of 93% over 5000 cycles.
Co-reporter:Haijing Liu, Ling-Hua Jin, Ping He, Congxiao Wang and Yongyao Xia
Chemical Communications 2009 (Issue 44) pp:6813-6815
Publication Date(Web):05 Oct 2009
DOI:10.1039/B916918K
A facile approach is demonstrated for the preparation of mesoporous carbon nanowires in nanotubes, mesoporous carbon nanotubes and mesoporous carbon nanothorn microspheres by combining surfactant-templating self-assembly of organic resols with different MnO2 hard templates, and they deliver excellent capacitive performance for supercapacitor applications.
Co-reporter:Jia-Yan Luo, Li-Juan Chen, Yu-Jun Zhao, Ping He, Yong-Yao Xia
Journal of Power Sources 2009 Volume 194(Issue 2) pp:1075-1080
Publication Date(Web):1 December 2009
DOI:10.1016/j.jpowsour.2009.06.050
We report that a partially oxygen deficient LiTi2(PO4)3 shows a much better rate capability as a cathode material for lithium-ion batteries compared to stoichiometric LiTi2(PO4)3. A combination of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electrochemistry, and first-principles calculations was used to determine and rationalize the structural and electrical changes that occur with different heat treatment atmospheres. XRD and XPS experiments confirmed that some Ti4+ transformed to Ti3+ in oxygen deficient LiTi2(PO4)3 heat treated under N2; Ti3+ was detected and the lattice parameter increased compared to that of LiTi2(PO4)3. Electrical conductivity measurements indicated an increase in the electronic conductivity of nearly two orders of magnitude for the oxygen deficient LiTi2(PO4)3 sample compared to LiTi2(PO4)3. First-principles calculations suggest that the oxygen vacancies could be formed in LiTi2(PO4)3 under oxygen-poor conditions, and this may significantly decrease the donor levels of other possible donor defects and thus improve the electronic mobility.
Co-reporter:Ping He, Jia-Yan Luo, Xin-Hui Yang, Yong-Yao Xia
Electrochimica Acta 2009 Volume 54(Issue 28) pp:7345-7349
Publication Date(Web):1 December 2009
DOI:10.1016/j.electacta.2009.07.062
We report the preparation of Li0.33MnO2 nanorods from γ-MnO2 nanorods reacted with LiNO3 by a low temperature solid-state reaction method. The Li0.33MnO2 nanorods tend to be oriented along the b-axis, and show an improved rate capability and cycling performance as positive electrode for lithium battery. It delivers a discharge capacity of 199 and 129 mAh/g at the current rate of 0.1 C (20 mA/g) and 2 C, respectively, and keeps 92% of initial capacity over 100 cycles. Li0.33MnO2 nanorods reduce both the electrode bulk resistance and charge-transfer resistance for lithium-ion intercalation. The advantage of nanorods results from good electrical conduction, appropriate length of nanorod and small volume expansion from appropriate orientations of tunnels structure.
Co-reporter:Xiao-Ming Wang, Yong-Yao Xia
Electrochimica Acta 2009 Volume 54(Issue 28) pp:7525-7530
Publication Date(Web):1 December 2009
DOI:10.1016/j.electacta.2009.08.007
Co-reporter:Xin-hui Yang, Ping He, Yong-yao Xia
Electrochemistry Communications 2009 Volume 11(Issue 6) pp:1127-1130
Publication Date(Web):June 2009
DOI:10.1016/j.elecom.2009.03.029
A mesocellular carbon foam (MCF-C) was prepared by nanocasting technology using mesocellular foam (MCF) silica hard template. The obtained carbon sample exhibits bimodal mesopores with narrow pore size distribution, centered at 4.3 and 30.4 nm. The MCF-C was evaluated as positive electrode in lithium/oxygen battery. It showed a higher discharge capacity, about 40% increased capacity compared to several commercial carbon black. The enhanced performance is probably ascribed to their large pore volumes and ultra-large mesoporous structures, which allow more lithium oxide deposit during discharge process.
Co-reporter:Xiao-Ming Wang, Yong-Yao Xia
Electrochemistry Communications 2009 Volume 11(Issue 1) pp:28-30
Publication Date(Web):January 2009
DOI:10.1016/j.elecom.2008.10.008
FexC–C hybrid material as a support for Pt anode catalyst in direct formic acid fuel cell was investigated for the first time. The resultant Pt/FexC–C catalysts were prepared by using a simple reduction reaction to load Pt on FexC–C hybrid material, which was synthesized through the carbonization of sucrose and Fe(NO3)3. It was found that the Pt/FexC–C catalysts exhibited excellent catalytic activity for formic acid electrooxidation. The great improvement in the catalytic performance is attributed to the fact that FexC–C hybrid material ameliorated the tolerance to CO adsorption of Pt and facilitated the uniform dispersion of Pt.
Co-reporter:Yong-Gang Wang;Wen Wu;Liang Cheng;Ping He;Cong-Xiao Wang
Advanced Materials 2008 Volume 20( Issue 11) pp:2166-2170
Publication Date(Web):
DOI:10.1002/adma.200701708
Co-reporter:Feng Li, Qing-Qing Zou, Yong-Yao Xia
Journal of Power Sources 2008 Volume 177(Issue 2) pp:546-552
Publication Date(Web):1 March 2008
DOI:10.1016/j.jpowsour.2007.10.097
A new type of CoO nanoparticles encapsulated by graphitable hollow carbon sphere (GHCS) composite material was synthesized. The core–shell structure CoO/GHCS composite shows the improved cyclability as an anodic material in Li-ion battery. The core–shell composite containing 50 wt% CoO exhibits a reversible capacity of 584 mAh g−1 at a constant current density of 100 mA g−1 between 0 and 3.0 V (vs. Li+/Li), and remains a capacity retention of 95% after 50th cycle. The improvement could be attributed to that the GHCS with a good electronic conductivity and high surface severs as dispersing medium to prevent CoO nanoparticles from aggregating, and provide the enough space to buffer the volume change during the Li-ion insertion and extraction reactions in CoO nanoparticles.
Co-reporter:Guo-Xian Ma, Yong-Gang Wang, Cong-Xiao Wang, Tian-Hong Lu, Yong-Yao Xia
Electrochimica Acta 2008 Volume 53(Issue 14) pp:4748-4753
Publication Date(Web):30 May 2008
DOI:10.1016/j.electacta.2008.01.092
We developed a novel mesoporous carbon/whisker-like carbon (MCWC) composite which can promote the direct electron transfer of hemoglobin (Hb) immobilized on its surface. The cyclic voltammetric results showed that Hb immobilized on the surface of the MCWC composite could undergo a direct quasi-reversible electrochemical reaction. Its formal redox potential, E0′ is −0.313 V in the phosphate buffer solution (pH 6.9) at a scan rate of 200 mV/s and is almost independent of the scan rate in the range of 100–600 mV/s. The dependence of E0′ on the pH of phosphate buffer solution indicated that the redox reaction of Hb includes a one-electron-transfer reaction process coupled with one-proton-transfer. The experiment obtained larger value of electron transfer rate constant, ks, than that of Hb immobilized on other carriers reported previously due to its special structure of loosely packed nanometer-scale carbon whiskers and thus formed “V-type” nano-pores. Furthermore, Hb immobilized on the surface of the MCWC composite can retain the stable bioelectrocatalytic activity for the reduction of H2O2.
Co-reporter:Jing-jun Zhang, Ping He, Yong-yao Xia
Journal of Electroanalytical Chemistry 2008 Volume 624(1–2) pp:161-166
Publication Date(Web):1 December 2008
DOI:10.1016/j.jelechem.2008.09.003
The kinetics of Li-ion intercalation/alloying into Cu6Sn5 electrode was determined by potentiostatic intermittent titration technique (PITT) and electrochemical impedance spectroscopy (EIS) method. Although the Li-ion diffusion coefficient (DLi) values are relatively high (from 10−11 to 10−10 cm2/s) in the most voltage range, two minima (below 10−11 cm2/s) in the DLi vs. voltage curve were observed at ∼0.4 and 0.1 V, coinciding with the voltage plateau in the charge/discharge curves, indicating reversible structural phase transition or order/disorder transition in the compound. The DLi derived from PITT and EIS were confirmed well both in the magnitudes and in the variation within Li composition (voltage) range.
Co-reporter:Huan-Ming Xiong ;Xiao-Yan Guan;Ling-Hua Jin;Wen-Wen Shen Dr.;Hao-Jie Lu
Angewandte Chemie International Edition 2008 Volume 47( Issue 22) pp:4204-4207
Publication Date(Web):
DOI:10.1002/anie.200705942
Co-reporter:Jia-Yan Luo ; Huan-Ming Xiong
The Journal of Physical Chemistry C 2008 Volume 112(Issue 31) pp:12051-12057
Publication Date(Web):July 11, 2008
DOI:10.1021/jp800915f
Nanostructured lithium intercalated compound has been demonstrated to be the most promising approach to improve the powder density of lithium ion batteries because of it providing a relatively short Li ion diffusion path. While the conventional nanostructured LiMn2O4, typically prepared at low temperatures, were almost all polycrystalline and low crystallinity, which would impair the stability of the crystallographic structure and charge−discharge cycling ability of LiMn2O4. In this paper, we systematically describe a topochemical method for successful synthesis of LiMn2O4 nanorods, nanothorn microspheres, and hollow nanospheres, and their electrochemical lithium insertion/desertion properties are extensively studied. We also investigated the effects of particle size, morphology, synthesis method, and crystal structure on the electrochemical properties of spinel LiMn2O4. The method described in the present work may assist in the design of novel nanostructured materials for application in a lithium ion battery.
Co-reporter:J.-Y. Luo;Y.-Y. Xia
Advanced Functional Materials 2007 Volume 17(Issue 18) pp:
Publication Date(Web):26 NOV 2007
DOI:10.1002/adfm.200700638
Porous, highly crystalline Nasicon-type phase LiTi2(PO4)3 has been prepared by a novel poly(vinyl alcohol)-assisted sol–gel route and coated by a uniform and continuous nanometers-thick carbon thin film using chemical vapor deposition technology. The as-prepared LiTi2(PO4)3 exhibits excellent electrochemical performance both in organic and aqueous electrolytes, and especially shows good cycling stability in aqueous electrolytes. An aqueous lithium-ion battery consisting of a combination of LiMn2O4 cathode, LiTi2(PO4)3 anode, and a 1 M Li2SO4 electrolyte has been constructed. The cell delivers a capacity of 40 mA h g–1 and a specific energy of 60 W h kg–1 with an output voltage of 1.5 V based on the total weight of the active electrode materials. It also exhibits an excellent cycling stability with a capacity retention of 82 % over 200 charge/discharge cycles, which is much better than any aqueous lithium-ion battery reported.
Co-reporter:Huan-Ming Xiong, Dong-Ping Xie, Xiao-Yan Guan, Yu-Jing Tan and Yong-Yao Xia
Journal of Materials Chemistry A 2007 vol. 17(Issue 24) pp:2490-2496
Publication Date(Web):02 Apr 2007
DOI:10.1039/B700176B
Two kinds of ZnO@polymer core–shell nanoparticles were prepared through polymerization initiated by the inherent free radicals on the ZnO surface. The as-prepared quantum dots exhibited intense blue fluorescence. They were used as raw materials to synthesize blue-emitting ZnO@polymer core–shell microspheres which were very stable, even in aqueous solutions of strong acids or alkalis. These microspheres, as stable aqueous suspensions, showed moderate quantum yields, and their self-assembly behavior and biomedical application could be expected.
Co-reporter:Jing-jun Zhang, Yi-min Zhang, Xiao Zhang, Yong-yao Xia
Journal of Power Sources 2007 Volume 167(Issue 1) pp:171-177
Publication Date(Web):1 May 2007
DOI:10.1016/j.jpowsour.2007.02.012
A series of Ni doped NixCu6−xSn5 (x = 0, 0.5, 1, 2, 4) alloys were prepared by mechanical alloying, followed by annealing at 400 °C. The Ni doped alloys show the similar structure with that of Cu6Sn5 and Ni3Sn2, which can be indexed to a hexagonal Ni2In type cell, but differ in the electrochemical performance as the anodes of Li-ion batteries. The electrochemical tests show that the cycling reversibility of NixCu6−xSn5 increases at the expense of the reversible capacity with the increasing amount of Ni content. The proper amount Ni doped alloy, Ni2Cu4Sn5 showed better cycle performance with a reversible capacity of 200 mAh g−1 (1680 mAh ml−1). The relative stability of the alloy was also investigated using the first-principles density-functional theory with pseudopotentials and plane wave basis (VASP).
Co-reporter:Jia-Yan Luo, Xi-Li Li, Yong-Yao Xia
Electrochimica Acta 2007 Volume 52(Issue 13) pp:4525-4531
Publication Date(Web):20 March 2007
DOI:10.1016/j.electacta.2006.12.049
Highly crystalline spinel LiMn2O4 was successfully synthesized by annealing lithiated MnO2 at a relative low temperature of 600 °C, in which the lithiated MnO2 was prepared by chemical lithiation of the electrolytic manganese dioxide (EMD) and LiI. The LiI/MnO2 ratio and the annealing temperature were optimized to obtain the pure phase LiMn2O4. With the LiI/MnO2 molar ratio of 0.75, and annealing temperature of 600 °C, the resulting compounds showed a high initial discharge capacity of 127 mAh g−1 at a current rate of 40 mAh g−1. Moreover, it exhibited excellent cycling and high rate capability, maintaining 90% of its initial capacity after 100 charge–discharge cycles, at a discharge rate of 5 C, it kept more than 85% of the reversible capacity compared with that of 0.1 C.
Co-reporter:Guo-Xian Ma, Tian-Hong Lu, Yong-Yao Xia
Bioelectrochemistry 2007 Volume 71(Issue 2) pp:180-185
Publication Date(Web):November 2007
DOI:10.1016/j.bioelechem.2007.04.002
It is reported for the first time that hemoglobin (Hb) was immobilized on the surface of carbon black powders modified at the surface of a glassy carbon electrode. The cyclic voltammetric results showed that the immobilized Hb could undergo a direct quasi-reversible electrochemical reaction. Its formal potential, E0, is − 0.330 V in phosphate buffer solution (pH 6.9) at a scan rate of 100 mV/s and is almost independent of the scan rate in the range of 40–200 mV/s. The dependence of E0, on the pH of the buffer solution indicated that the conversion of Hb–Fe(III)/Hb–Fe(II) is a one-electron-transfer reaction process coupled with one-proton-transfer. The experimental results also demonstrated that the immobilized Hb retained its bioelectrocatalytic activity for the reduction of H2O2. Furthermore, the immobilized Hb can be stored at 4 °C for several weeks without any loss of the enzyme activity. Thus, the immobilized Hb may be used as a biocathodic catalyst in biofuel cells.
Co-reporter:Xiao Zhang, Jing-Jun Zhang, Yong-Yao Xia
Journal of Photochemistry and Photobiology A: Chemistry 2007 Volume 185(2–3) pp:283-288
Publication Date(Web):25 January 2007
DOI:10.1016/j.jphotochem.2006.06.022
Density functional theory (DFT) and time-dependent DFT method have been employed to analyze the tetradeprotonated complexes of polypyridyl ruthenium dyes cis-Ru(4,4′-COOH-2,2′-bpy)2(L)2 (L = NCS, CN and dcbpy; dcbpy = 2,2′-bipyridine-4,4′-carboxylate). The absorption spectra of these complexes in ethanol solution can be well reproduced with theoretical method. The nature of their absorption bands are assigned unambiguously. According to the computational results, energy levels of the singlet and triplet excited states of cis-Ru(4,4′-COO−-2,2′-bpy)2(NCS)2 are advantage for the charge injection. Its intense and broad absorption bands as well as favorable excited-state energy levels are key causes for its outstanding efficiency.
Co-reporter:H.-M. Xiong;Z.-D. Wang;Y.-Y. Xia
Advanced Materials 2006 Volume 18(Issue 6) pp:748-751
Publication Date(Web):15 MAR 2006
DOI:10.1002/adma.200501899
Strong blue fluorescence—with a quantum yield over 80 % (see figure)—of ultrastable (ZnO)polymer core–shell nanoparticles is suggested to arise by a luminescence mechanism different from that for conventional ZnO nanoparticles. The stable particles are produced by methacrylic-group-modified ZnO nanoparticles reacting with liquid monomers, the polymerization being initiated by free radicals pre-existing on the ZnO nanoparticle surfaces.
Co-reporter:Y.-G. Wang;H.-Q. Li;Y.-Y. Xia
Advanced Materials 2006 Volume 18(Issue 19) pp:2619-2623
Publication Date(Web):14 SEP 2006
DOI:10.1002/adma.200600445
Supercapacitor electrode materials must exhibit high specific capacitance and high-rate charge–discharge ability. The ordered whiskerlike polyaniline (PANI) reported here, which was synthesized in situ on the surface of mesoporous carbon by a novel process, is demonstrated to have these properties thanks to its ordered nanometer-sized “thorns” (see figure) and the V-shaped nanopores between them.
Co-reporter:Huan-Ming Xiong, Zi-Dong Wang, Dong-Ping Xie, Liang Cheng and Yong-Yao Xia
Journal of Materials Chemistry A 2006 vol. 16(Issue 14) pp:1345-1349
Publication Date(Web):20 Jan 2006
DOI:10.1039/B514346B
Solid polymer nanocomposite electrolytes composed of polyethylene oxide (PEO) macromolecules, LiN(CF3SO2)2 (LiTFSI) and polyether-grafted nano-ZnO (designated ZnO(PEGME)), are prepared and characterized in comparison with the prototypical PEO–LiTFSI film and that doped with conventional acetate group modified ZnO nanoparticles (designated ZnO(Ac)). High resolution transmission electron microscopic (HRTEM) results show that ZnO nanoparticles are dispersed homogeneously in the present PEO–LiTFSI–ZnO(PEGME) films, while those particles in PEO–LiTFSI–ZnO(Ac) aggregate badly. Atomic force microscopic (AFM) analyses prove that after storage at room temperature for a month, PEO–LiTFSI forms large dendrites while only a small amount of tiny crystals can be observed in the PEO–LiTFSI–ZnO(PEGME) film. In contrast, ZnO(Ac) particles agglomerate around the PEO–LiTFSI dendrites and separate from the original phase. This is the first direct observation on the micromorphology of the SPE films after long-term storage, which elucidates why the PEO–LiTFSI–ZnO(PEGME) electrolyte is much more stable than its counterparts. Conductivity evolutions, Li+ transport number measurements and cycle performances of the above-mentioned three typical films in all-solid-state lithium batteries also suggest that the structural merits of the polyether-grafted nanoparticles render this type of SPEs attractive in the future applications.
Co-reporter:H.-M. Xiong;Z.-D. Wang;D.-P. Liu;J.-S. Chen;Y.-G. Wang;Y.-Y. Xia
Advanced Functional Materials 2005 Volume 15(Issue 11) pp:
Publication Date(Web):5 SEP 2005
DOI:10.1002/adfm.200500167
A series of new polymer nanocomposites, ZnO(PEGME), in which ZnO nanoparticles and poly(ethylene glycol methyl ether) (PEGME) molecules are connected by covalent bonds, have been synthesized by a sol–gel route and purified by a non-solvent method. Various characterization techniques have been employed to determine the compositions and structures of the ZnO(PEGME)s, and their luminescent properties and ionic conductivities (after dissolving lithium salts to form solid polymer electrolytes) have been measured and compared with their counterparts—polymer nanocomposites prepared by mixing PEGME and ZnO nanoparticles physically. These comparisons prove that ZnO(PEGME) hybrids derived from chemical reactions have much better properties and stabilities than their counterparts. As a result, tunable photoluminescence of ZnO nanoparticles and stable conductivity of solid polymer electrolytes have been realized successfully.
Co-reporter:Yuanjin Du, Mengyan Hou, Dandan Zhou, Yonggang Wang, ... Yongyao Xia
Journal of Energy Chemistry (May 2014) Volume 23(Issue 3) pp:315-323
Publication Date(Web):1 May 2014
DOI:10.1016/S2095-4956(14)60153-4
In the present work, an interconnected sandwich carbon/Si-SiO2/carbon nanospheres composite was prepared by template method and carbon thermal vapor deposition (TVD). The carbon conductive layer can not only efficiently improve the electronic conductivity of Si-based anode, but also play a key role in alleviating the negative effect from huge volume expansion over discharge/charge of Si-based anode. The resulting material delivered a reversible capacity of 1094 mAh/g, and exhibited excellent cycling stability. It kept a reversible capacity of 1050 mAh/g over 200 cycles with a capacity retention of 96%.The interconnected sandwich carbon/Si-SiO2/carbon nanospheres composite exhibits good battery profile with a reversible capacity of 1094 mAh/g and a reversible capacity of 1050 mAh/g over 200 cycles with a capacity retention of 96%.Download full-size image
Co-reporter:Jia-Yan Luo, Yong-Yao Xia
Journal of Power Sources (1 January 2009) Volume 186(Issue 1) pp:224-227
Publication Date(Web):1 January 2009
DOI:10.1016/j.jpowsour.2008.09.063
In this work, we reported an asymmetric supercapacitor in which active carbon (AC) was used as a positive electrode and carbon-coated LiTi2(PO4)3 as a negative electrode in 1 M Li2SO4 aqueous electrolyte. The LiTi2(PO4)3/AC hybrid supercapacitor showed a sloping voltage profile from 0.3 to 1.5 V, at an average voltage near 0.9 V, and delivered a capacity of 30 mAh g−1 and an energy density of 27 Wh kg−1 based on the total weight of the active electrode materials. It exhibited a desirable profile and maintained over 85% of its initial energy density after 1000 cycles. The hybrid supercapacitor also exhibited an excellent rate capability, even at a power density of 1000 W kg−1, it had a specific energy 15 Wh kg−1 compared with 24 Wh kg−1 at the power density about 200 W kg−1.
Co-reporter:Yao Liu, Jingyuan Liu, Mengyan Hou, Long Fan, Yonggang Wang and Yongyao Xia
Journal of Materials Chemistry A 2017 - vol. 5(Issue 22) pp:NaN10908-10908
Publication Date(Web):2017/05/04
DOI:10.1039/C7TA03173D
Sodium-ion batteries have been considered as promising alternatives to the current lithium-ion batteries owing to their low cost and abundant raw material. The major challenge of their practical implementation is the lack of favourable anode material. Spinel Li4Ti5O12 has been regarded as a potential anode material for its superior capability of sodium-ion storage and relatively appropriate operating voltage. However, the low intrinsic ionic and electronic conductivity of spinel Li4Ti5O12 still remains as its major drawback. Herein, carbon-coated Li4Ti5O12 nanoparticles have been synthesized through a solid-state reaction and a chemical vapour deposition method and used as an anode material for sodium-ion battery. The composite structure demonstrates excellent stability and an initial discharge specific capacity of 120.1 mA h g−1, which is maintained at 101.5 mA h g−1 after 500 cycles corresponding to 85% of capacity retention at a current density of 0.1 A g−1. In addition, a full cell was fabricated with carbon-coated Na3V2(PO4)3 as a positive electrode, which displayed discharge specific capacities of 138.5 mA h g−1 that was maintained at 114.7 mA h g−1 after 50 cycles at a current density of 0.05 A g−1, and the capacity retention was 82.8%. The results indicated that the Li4Ti5O12 nanoparticle with a carbon layer shows a promising electrochemical performance as anode materials in sodium-ion batteries.
Co-reporter:Xiao-Ming Wang, Ming-E Wang, Dan-Dan Zhou and Yong-Yao Xia
Physical Chemistry Chemical Physics 2011 - vol. 13(Issue 30) pp:NaN13597-13597
Publication Date(Web):2011/06/24
DOI:10.1039/C1CP21680E
The pathway of formic acid electrooxidation strongly depends on the amount of three neighbouring Pt or Pd atoms in the surface of Pd- or Pt-based catalysts. Here, Pt decorated Pd/C nanoparticles (the optimal atomic ratio, Pd:Pt = 20:1) were designed and then synthesized through a facile galvanic replacement reaction where the amount of three neighbouring Pt or Pd atoms markedly decreased. As a result, discontinuous Pd and Pt atoms suppressed CO formation and exhibited unprecedented catalytic activity and stability toward formic acid electrooxidation while the cost was almost the same as that of Pd/C.
Co-reporter:Wang-jun Cui, Feng Li, Hai-jing Liu, Cong-xiao Wang and Yong-yao Xia
Journal of Materials Chemistry A 2009 - vol. 19(Issue 39) pp:NaN7207-7207
Publication Date(Web):2009/08/20
DOI:10.1039/B909769D
A core–shell-structure carbon-coated nanoscale Cu6Sn5 is prepared by using an in situpolymerization method integrated with a surface modification technology. The composite combines the merits of intermetallic compounds and nano-sized anode materials, and exhibits an excellent cycling stability. The improvement in the cycling stability could be attributed to the fact that the well-coated carbon layer can effectively prevent the encapsulated low melting point alloy from out-flowing in a high-temperature treatment process, as well as preventing aggregation and pulverization of nano-sized Cu6Sn5 alloy particles during charge/discharge cycling.
Co-reporter:Hai-Jing Liu;Wang-Jun Cui;Ling-Hua Jin;Cong-Xiao Wang
Journal of Materials Chemistry A 2009 - vol. 19(Issue 22) pp:
Publication Date(Web):2009/06/07
DOI:10.1039/B819820A
A two-step template approach was demonstrated for preparation of the three-dimensional ordered mesoporous carbon sphere arrays. The ordered macroporous silica skeleton was formed from silicon alkoxide precursor templating around polystyrene (latex) spheres, and removal of the polystyrene spheres. These preforms as hard templates were infiltrated with a solution mixture of amphiphilic triblock copolymer PEO-PPO-PEO and soluble resol. By combining evaporation-induced surfactant-templating organic resol self-assembly with thermosetting, carbonization and hydrofluoric acid extraction of silica, the obtained mesoporous carbon has a pore size of 10.4 nm, interconnected window size of about 60 nm, surface area of 601 m2/g and pore volume of 1.70 cm3/g. The electrochemical properties as an electrode material for supercapacitor applications were investigated in nonaqueous electrolyte. They show rectangular-shaped cyclic voltammetry curves over a wide range of scan rates even up to 200 mV/s between 0 and 3 V, and deliver a large capacitance of 14 µF/cm2 (84 F/g), and good cycling stability with capacitance retention of 93% over 5000 cycles.
Co-reporter:Huan-Ming Xiong, Dong-Ping Xie, Xiao-Yan Guan, Yu-Jing Tan and Yong-Yao Xia
Journal of Materials Chemistry A 2007 - vol. 17(Issue 24) pp:NaN2496-2496
Publication Date(Web):2007/04/02
DOI:10.1039/B700176B
Two kinds of ZnO@polymer core–shell nanoparticles were prepared through polymerization initiated by the inherent free radicals on the ZnO surface. The as-prepared quantum dots exhibited intense blue fluorescence. They were used as raw materials to synthesize blue-emitting ZnO@polymer core–shell microspheres which were very stable, even in aqueous solutions of strong acids or alkalis. These microspheres, as stable aqueous suspensions, showed moderate quantum yields, and their self-assembly behavior and biomedical application could be expected.
Co-reporter:Hai-Jing Liu, Xiao-Ming Wang, Wang-Jun Cui, Yu-Qian Dou, Dong-Yuan Zhao and Yong-Yao Xia
Journal of Materials Chemistry A 2010 - vol. 20(Issue 20) pp:NaN4230-4230
Publication Date(Web):2010/04/08
DOI:10.1039/B925776D
Mesoporous carbons with large uniform pore sizes and high surface areas are of great interest due to their potential applications in electrochemical double layer capacitors (EDLCs), hydrogen storage, separation and catalysis. Here, we report a facile synthesis approach to highly ordered mesoporous carbon nanofiber arrays (MCNAs) by combining surfactant-templating self-assembly of organic resols with a natural crab shell hard-templating process. The obtained materials consist of a mesoporous carbon nanofiber (70 nm in mean diameter and 11 nm in mesopore), an interspacing void of 70 nm between nanofibers, and 1 micrometre of pores between nanofiber arrays. The unique structure (ordered mesopores, macroporous voids and partially graphitic framework) provides a more favorable path for electrolyte penetration and transportation, good electronic conductivity, as well as possess a large specific surface area (1270 m2 g−1) and more vacancies or defects in a graphite plane, which facilitate uniform distribution of metal nanoparticles and a synergistic effect between the nanoparticles and MCNAs, and give rise to promising electrocatalytic activity as a supporting medium for Pt in direct methanol fuel cells. The resultant materials also have excellent capacitive performance for supercapacitor application.
Co-reporter:Jinlong Liu, Long Chen, Mengyan Hou, Fei Wang, Renchao Che and Yongyao Xia
Journal of Materials Chemistry A 2012 - vol. 22(Issue 48) pp:NaN25387-25387
Publication Date(Web):2012/10/12
DOI:10.1039/C2JM35026B
Well-crystallized and high-performance xLi2MnO3·(1 − x)LiMn1/3Ni1/3Co1/3O2 (x = 0.3, 0.5, and 0.7) structurally integrated nanomaterials are prepared by a facile molten-salt strategy. The effects of heat-treatment temperature, time, and the molar ratio of KCl flux to reaction precursor on the particle size as well as the electrochemical properties are explored. Our results demonstrate that a 0.5Li2MnO3·0.5LiMn1/3Ni1/3Co1/3O2 electrode delivers a high reversible capacity of 313 mA h g−1 with significant enhancement in the initial coulombic efficiency (87%) at room temperature, exhibits superior rate capability and shows improved electrochemical properties over a wide temperature range, in particular at low temperature.
Co-reporter:Xiao-Ming Wang, Dan-Dan Zhou, Qing-Qing Zou and Yong-Yao Xia
Journal of Materials Chemistry A 2012 - vol. 22(Issue 30) pp:NaN15426-15426
Publication Date(Web):2012/06/01
DOI:10.1039/C2JM32547K
The application of anionic stabilizers is of great importance in the synthesis of supported metal nanoparticles with small and uniform size and high dispersion. Herein, we extensively studied the influence of four congeneric anionic stabilizers on the morphology of carbon-supported Pd nanoparticles, and evaluated the efficacy of anionic stabilizers by testing the catalytic property of supported Pd nanoparticles toward formic acid electrooxidation. The results reveal that the morphology of carbon-supported Pd nanoparticles strongly depends on the steric hindrance and coordination effects of the anionic stabilizers. To be more specific, (1) large steric hindrance of anionic stabilizers is beneficial to form a small and uniform Pd particle size; (2) coordination compound formation between Pd ions and stabilizer molecules facilitates the dispersion of Pd nanoparticles on carbon black; and (3) both large steric hindrance and coordination compound formation can decrease the deposition of Pd nanoparticles in the micropores of carbon black. This work provides a reference point for future work aspiring to develop even better anionic stabilizers for the synthesis of supported metal nanoparticles.
Co-reporter:Fei Wang, Wei Li, Mengyan Hou, Chao Li, Yonggang Wang and Yongyao Xia
Journal of Materials Chemistry A 2015 - vol. 3(Issue 4) pp:NaN1708-1708
Publication Date(Web):2014/11/06
DOI:10.1039/C4TA05072J
Novel sandwich-like Cr2O3–graphite intercalation composites (Cr2O3–GICs) were synthesized via an intercalation–transformation method. Cr2O3 nanoparticles (NPs) are intercalated between the adjacent carbon layers of graphite and tightly immobilized. The Cr2O3–GICs show promising performance as anode materials for LIBs with a reversible capacity of about 480 mA h g−1 and a relatively low lithium insertion potential. More importantly, the Cr2O3–GICs demonstrate an extremely promising stable cycling performance with over 100% capacity retention after 1000 cycles. Furthermore, the intercalation–transformation method also provides another fabrication method of graphene-based assembled materials.
Co-reporter:Yonggang Wang, Yanfang Song and Yongyao Xia
Chemical Society Reviews 2016 - vol. 45(Issue 21) pp:NaN5950-5950
Publication Date(Web):2016/08/22
DOI:10.1039/C5CS00580A
Electrochemical capacitors (i.e. supercapacitors) include electrochemical double-layer capacitors that depend on the charge storage of ion adsorption and pseudo-capacitors that are based on charge storage involving fast surface redox reactions. The energy storage capacities of supercapacitors are several orders of magnitude higher than those of conventional dielectric capacitors, but are much lower than those of secondary batteries. They typically have high power density, long cyclic stability and high safety, and thus can be considered as an alternative or complement to rechargeable batteries in applications that require high power delivery or fast energy harvesting. This article reviews the latest progress in supercapacitors in charge storage mechanisms, electrode materials, electrolyte materials, systems, characterization methods, and applications. In particular, the newly developed charge storage mechanism for intercalative pseudocapacitive behaviour, which bridges the gap between battery behaviour and conventional pseudocapacitive behaviour, is also clarified for comparison. Finally, the prospects and challenges associated with supercapacitors in practical applications are also discussed.
Co-reporter:Lina Wang, Jingyuan Liu, Servane Haller, Yonggang Wang and Yongyao Xia
Chemical Communications 2015 - vol. 51(Issue 32) pp:NaN6999-6999
Publication Date(Web):2015/03/16
DOI:10.1039/C5CC00444F
A newly designed hybrid separator composed of a glassy fiber paper and a microporous membrane is effectively integrated into a Li–S battery. Superior cell performance up to 500 cycles is achieved even with commercially available pristine sulfur as cathode material. This fascinating study demonstrates a largely restrained polysulfides shuttle process toward practical Li–S battery application.
Co-reporter:Haijing Liu, Ling-Hua Jin, Ping He, Congxiao Wang and Yongyao Xia
Chemical Communications 2009(Issue 44) pp:NaN6815-6815
Publication Date(Web):2009/10/05
DOI:10.1039/B916918K
A facile approach is demonstrated for the preparation of mesoporous carbon nanowires in nanotubes, mesoporous carbon nanotubes and mesoporous carbon nanothorn microspheres by combining surfactant-templating self-assembly of organic resols with different MnO2 hard templates, and they deliver excellent capacitive performance for supercapacitor applications.
Co-reporter:Dan-Dan Zhou, Yuan-Jin Du, Yan-Fang Song, Yong-Gang Wang, Cong-Xiao Wang and Yong-Yao Xia
Journal of Materials Chemistry A 2013 - vol. 1(Issue 4) pp:NaN1200-1200
Publication Date(Web):2012/10/31
DOI:10.1039/C2TA00533F
A series of ordered mesoporous/microporous carbon materials with controllable micropore size was prepared from chlorination of ordered mesoporous titanium carbide/carbon composites obtained by an evaporation induced self-assembly approach. The proportion of micropores can be tuned easily by changing the Ti content in the parent TiC/C composites in order to study the effect of micropore content on rate capability and specific capacitance. Under the optimized condition, an optimal mesoporous/microporous carbon with moderate micropores (52.4% in volume) was obtained. It has a high surface area (1698 m2 g−1) and a large pore volume (1.17 cm3 g−1), with the mesopore size centered at 4.4 nm, and micropore sizes of 0.52, 0.76 and 1.35 nm. It exhibits a high capacitance of 132 F g−1 at the current density of 500 mA g−1 and good rate capability with capacitance retention of 79% at a scan rate of 2000 mV s−1vs. 20 mV s−1 in nonaqueous electrolyte, and also shows a good cycling stability with capacitance retention of 84% over 5000 cycles.
Co-reporter:Huanming Xiong, Weizhi Shen, Binkun Guo, Shouhang Bo, Wangjun Cui, Liquan Chen, Hong Li and Yongyao Xia
Journal of Materials Chemistry A 2011 - vol. 21(Issue 9) pp:NaN2847-2847
Publication Date(Web):2011/01/24
DOI:10.1039/C0JM03558K
A series of PEG–SnO2 nanocomposites has been investigated as anode materials for lithium batteries. They exhibited an unexpectedly high lithium storage over the theoretical capacity of SnO2. The origin of such extra capacity cannot be interpreted by the conventional lithium storage mechanisms of anode materials.
Co-reporter:Liang Cheng, Jing Yan, Guan-Nan Zhu, Jia-Yan Luo, Cong-Xiao Wang and Yong-Yao Xia
Journal of Materials Chemistry A 2010 - vol. 20(Issue 3) pp:NaN602-602
Publication Date(Web):2009/11/20
DOI:10.1039/B914604K
A simple approach is proposed to synthesize nanostructured Li4Ti5O12 spinel materials with different morphologies (nanorods, hollow spheres and nanoparticles), in which the TiO2 precursor is first coated with a conductive carbon layer by the chemical vapour decomposition (CVD) method, followed by a solid-state reaction with lithium salt. The Li4Ti5O12 obtained was characterised by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), as well as galvanostatic measurements. The results indicate that, by employing the carbon pre-coating process, the carbon-coated nanostructured Li4Ti5O12 can maintain the initial morphologies of the TiO2 precursors and also show significant improvement in the rate capability for lithium-ion intercalation due to both good electronic conductivity and the short lithium-ion diffusion path.
