Co-reporter:Zhihong Li, Shaocheng Ye, Wei Wang, Qunjie Xu, Haimei Liu, Yonggang Wang, and Yongyao Xia
ACS Omega September 2017? Volume 2(Issue 9) pp:5726-5726
Publication Date(Web):September 12, 2017
DOI:10.1021/acsomega.7b01051
A free-standing flexible anode material for sodium storage with sandwich-structured characteristics was fabricated by modified vacuum filtration, consisting of stacked layers of Na2Ti3O7 nanowires@carbon nanotubes (NTO NW@CNT) and graphene oxide. The NTO NWs have a larger specific surface area for Na+ insertion/extraction with shortened ion diffusion pathways, accelerating the charge transfer/collection kinetics. The added CNTs both facilitate the uniform dispersion of the nanowires and nanotubes and also contribute to the connectivity of the nanowires, improving their conductivity. More importantly, the unique sandwichlike layered-structured film not only provides large numbers of electron-transfer channels and promotes the reaction kinetics during the charging and discharging process but also ensures the structural stability of the NTO NWs and the electrode. Electrochemical measurements suggest that this rationally designed structure endows the electrode with a high specific capacity and excellent cycling performance. A satisfactory reversible capacity as high as 92.5 mA h g–1 was achieved after 100 cycles at 2C; subsequently, the electrode also delivered 59.9 mA h g–1 after a further 100 cycles at 5C. Furthermore, after the rate performance test, the electrode could be continuously cycled for 100 cycles at a current density of 0.2C, which demonstrated that durable cyclic capacity with a high reversible capacity of 114.1 mA h g–1 was retained. This novel and low-cost fabrication procedure is readily scalable and provides a promising avenue for potential industrial applications.Topics: Batteries; Electric properties; Electron transfer; Fibers; Nanoclusters; Nanocomposites; Nanowires;
Co-reporter:Haipeng Lv, Xiujiao Gao, Qunjie Xu, Haimei Liu, Yong-Gang Wang, and Yongyao Xia
ACS Applied Materials & Interfaces November 22, 2017 Volume 9(Issue 46) pp:40394-40394
Publication Date(Web):October 26, 2017
DOI:10.1021/acsami.7b14761
Manganese oxides (MnO2) are regarded as typical and promising electrode materials for supercapacitors. However, the practical electrochemical performance of MnO2 is far from its theoretical value. Nowadays, numerous efforts are being devoted to the design and preparation of nanostructured MnO2 with the aim of improving its electrochemical properties. In this work, ultralong MnO2 nanowires were fabricated in a process induced by carbon quantum dots (CQDs); subsequently, a binder-free flexible electrode membrane was easily obtained by vacuum filtration of the MnO2 nanowires. The effects of the CQDs not only induced the formation of one-dimensional nanostructured MnO2, but also significantly improved the wettability between electrode and electrolyte. In other words, the MnO2 membrane demonstrated a superhydrophilic character in aqueous solution, indicating the sufficient and abundant contact probability between electrode and electrolyte. The binder-free flexible MnO2 electrode exhibited a preeminent specific capacitance of 340 F g–1 at 1 A g–1; even when the current density reached 20 A g–1, it still maintained 260 F g–1 (76% retention rate compared to that at 1 A g–1). Moreover, it also showed good cycling stability with 80.1% capacity retention over 10 000 cycles at 1 A g–1. Furthermore, an asymmetric supercapacitor was constructed using the MnO2 membrane and active carbon as the positive and negative electrodes, respectively, which exhibited a high energy density of 33.6 Wh kg–1 at 1.0 kW kg–1, and a high power density of 10 kW kg–1 at 12.5 Wh kg–1.Keywords: carbon quantum dots; flexible electrode; MnO2 nanowires; supercapacitor; superhydrophilicity;
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: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;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:Shaocheng Ye;Zhihong Li;Tianbing Song;Danhong Cheng;Qunjie Xu;Haimei Liu;Yonggang Wang
RSC Advances (2011-Present) 2017 vol. 7(Issue 89) pp:56743-56751
Publication Date(Web):2017/12/12
DOI:10.1039/C7RA12291H
NaTi2(PO4)3 is a promising anode material for sodium-ion batteries due to its sodium-super-ion-conductor type structure. However, the inherent low conductivity of the NaTi2(PO4)3 limits its cyclability and rate capability. Herein, to overcome these shortcomings, an electrode material that combines the hollow NaTi2(PO4)3 nanocubes with the reduced graphene oxide is synthesized by a simple hydrothermal method. The as-synthesized products demonstrate a high specific capacity of 128 mA h g−1, nearly achieving its theoretical capacity of the NaTi2(PO4)3 electrode at 0.1C; even when the discharging rate reached 50C, it still achieved a capacity retention of 60%. Simultaneously, the sample also shows stable cycling performance with a discharge capacity of 60 mA h g−1 after 500 cycles at a high rate of 20C. This excellent electrochemical performance of the NaTi2(PO4)3@rGO is attributed to the large surface area of the hollow structure and high conductivity of the three-dimensional reduced graphene oxide that facilitate the electrolyte to soak in, increase the contact area between the nanocubes and electrolyte, and speed up Na+/e− transfer in the nanocomposites. In addition, the unique hollow structure and the combination with the graphene could effectively accommodate the volume variation during repeated sodiation/desodiation processes.
Co-reporter:Ji-Shi Wei, Jie Chen, Hui Ding, Peng Zhang, Yong-Gang Wang, Huan-Ming Xiong
Journal of Power Sources 2017 Volume 364(Volume 364) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.jpowsour.2017.08.002
•Abundant functional groups from polymer dots (PDs) take part in faradic reactions.•PDs can bind onto graphene sheets tightly through chemical bonds.•PDs can effectively increase the surface areas and pore volumes of the composites.A series of polymer dots/graphene sheets composites with high densities are prepared and tested for supercapacitors. Polymer dots (PDs) are synthesized by one-step method at room temperature. They can effectively increase surface areas of the composites (almost 10 times), and the functional groups from PDs produce high pseudocapacitance, so that the samples exhibit high specific capacitances (e. g., 364.2 F cm−3 at 1 A g−1) and high cycling stability (e. g., more than 95% of the initial capacity retention over 10 000 cycles at different current densities). The optimal sample is employed to fabricate a symmetric supercapacitor, which exhibits an energy density up to 8 Wh L−1 and a power density up to 11 800 W L−1, respectively.Download high-res image (314KB)Download full-size image
Co-reporter:Huijuan Yu;Hanwen Li;Shouyi Yuan;Yuchi Yang;Jiahui Zheng;Jianhua Hu
Nano Research 2017 Volume 10( Issue 7) pp:2495-2507
Publication Date(Web):04 April 2017
DOI:10.1007/s12274-017-1454-1
Mesoporous carbons have been widely utilized as the sulfur host for lithium-sulfur (Li-S) batteries. The ability to engineer the porosity, wall thickness, and graphitization degree of the carbon host is essential for addressing issues that hamper commercialization of Li-S batteries, such as fast capacity decay and poor high-rate performance. In this work, highly ordered, ultrathin mesoporous graphitic-carbon frameworks (MGFs) having unique cage-like mesoporosity, derived from self-assembled Fe3O4 nanoparticle superlattices, are demonstrated to be an excellent host for encapsulating sulfur. The resulting S@MGFs exhibit high specific capacity (1,446 mAh·g–1 at 0.15 C), good rate capability (430 mAh·g–1 at 6 C), and exceptional cycling stability (~0.049% capacity decay per cycle at 1 C) when used as Li-S cathodes. The superior electrochemical performance of the S@MGFs is attributed to the many unique and advantageous structural features of MGFs. In addition to the interconnected, ultrathin graphitic-carbon framework that ensures rapid electron and lithium-ion transport, the microporous openings between adjacent mesopores efficiently suppress the diffusion of polysulfides, leading to improved capacity retention even at high current densities.
Co-reporter:Yao Liu;Bingchang Yang;Xiaoli Dong; Yonggang Wang; Yongyao Xia
Angewandte Chemie 2017 Volume 129(Issue 52) pp:16833-16837
Publication Date(Web):2017/12/22
DOI:10.1002/ange.201710555
AbstractLithium-ion batteries (LIBs) are being used to power the commercial electric vehicles (EVs). However, the charge/discharge rate and life of current LIBs still cannot satisfy the further development of EVs. Furthermore, the poor low-temperature performance of LIBs limits their application in cold climates and high altitude areas. Herein, a simple prelithiation method is developed to fabricate a new LIB. In this strategy, a Li3V2(PO4)3 cathode and a pristine hard carbon anode are used to form a primary cell, and the initial Li+ extraction from Li3V2(PO4)3 is used to prelithiate the hard carbon. Then, the self-formed Li2V2(PO4)3 cathode and prelithiated hard carbon anode are used to form a 4 V LIB. The LIB exhibits a maximum energy density of 208.3 Wh kg−1, a maximum power density of 8291 W kg−1 and a long life of 2000 cycles. When operated at −40 °C, the LIB can keep 67 % capacity of room temperature, which is much better than conventional LIBs.
Co-reporter:Chao Li;Ziyang Guo;Bingchang Yang;Yao Liu; Yonggang Wang; Yongyao Xia
Angewandte Chemie 2017 Volume 129(Issue 31) pp:9254-9258
Publication Date(Web):2017/07/24
DOI:10.1002/ange.201705017
AbstractThe utilization of CO2 in Li-CO2 batteries is attracting extensive attention. However, the poor rechargeability and low applied current density have remained the Achilles’ heel of this energy device. The gel polymer electrolyte (GPE), which is composed of a polymer matrix filled with tetraglyme-based liquid electrolyte, was used to fabricate a rechargeable Li-CO2 battery with a carbon nanotube-based gas electrode. The discharge product of Li2CO3 formed in the GPE-based Li-CO2 battery exhibits a particle-shaped morphology with poor crystallinity, which is different from the contiguous polymer-like and crystalline discharge product in conventional Li-CO2 battery using a liquid electrolyte. Accordingly, the GPE-based battery shows much improved electrochemical performance. The achieved cycle life (60 cycles) and rate capability (maximum applied current density of 500 mA g−1) are much higher than most of previous reports, which points a new way to develop high-performance Li-CO2 batteries.
Co-reporter:Chao Li;Ziyang Guo;Bingchang Yang;Yao Liu; Yonggang Wang; Yongyao Xia
Angewandte Chemie International Edition 2017 Volume 56(Issue 31) pp:9126-9130
Publication Date(Web):2017/07/24
DOI:10.1002/anie.201705017
AbstractThe utilization of CO2 in Li-CO2 batteries is attracting extensive attention. However, the poor rechargeability and low applied current density have remained the Achilles’ heel of this energy device. The gel polymer electrolyte (GPE), which is composed of a polymer matrix filled with tetraglyme-based liquid electrolyte, was used to fabricate a rechargeable Li-CO2 battery with a carbon nanotube-based gas electrode. The discharge product of Li2CO3 formed in the GPE-based Li-CO2 battery exhibits a particle-shaped morphology with poor crystallinity, which is different from the contiguous polymer-like and crystalline discharge product in conventional Li-CO2 battery using a liquid electrolyte. Accordingly, the GPE-based battery shows much improved electrochemical performance. The achieved cycle life (60 cycles) and rate capability (maximum applied current density of 500 mA g−1) are much higher than most of previous reports, which points a new way to develop high-performance Li-CO2 batteries.
Co-reporter:Dr. Ziyang Guo;Chao Li;Jingyuan Liu; Yonggang Wang; Yongyao Xia
Angewandte Chemie International Edition 2017 Volume 56(Issue 26) pp:7505-7509
Publication Date(Web):2017/06/19
DOI:10.1002/anie.201701290
AbstractLithium–air batteries when operated in ambient air generally exhibit poor reversibility and cyclability, because of the Li passivation and Li2O2/LiOH/Li2CO3 accumulation in the air electrode. Herein, we present a Li–air battery supported by a polymer electrolyte containing 0.05 m LiI, in which the polymer electrolyte efficiently alleviates the Li passivation induced by attacking air. Furthermore, it is demonstrated that I−/I2 conversion in polymer electrolyte acts as a redox mediator that facilitates electrochemical decomposition of the discharge products during recharge process. As a result, the Li–air battery can be stably cycled 400 times in ambient air (relative humidity of 15 %), which is much better than previous reports. The achievement offers a hope to develop the Li–air battery that can be operated in ambient air.
Co-reporter:Yao Liu;Bingchang Yang;Xiaoli Dong; Yonggang Wang; Yongyao Xia
Angewandte Chemie International Edition 2017 Volume 56(Issue 52) pp:16606-16610
Publication Date(Web):2017/12/22
DOI:10.1002/anie.201710555
AbstractLithium-ion batteries (LIBs) are being used to power the commercial electric vehicles (EVs). However, the charge/discharge rate and life of current LIBs still cannot satisfy the further development of EVs. Furthermore, the poor low-temperature performance of LIBs limits their application in cold climates and high altitude areas. Herein, a simple prelithiation method is developed to fabricate a new LIB. In this strategy, a Li3V2(PO4)3 cathode and a pristine hard carbon anode are used to form a primary cell, and the initial Li+ extraction from Li3V2(PO4)3 is used to prelithiate the hard carbon. Then, the self-formed Li2V2(PO4)3 cathode and prelithiated hard carbon anode are used to form a 4 V LIB. The LIB exhibits a maximum energy density of 208.3 Wh kg−1, a maximum power density of 8291 W kg−1 and a long life of 2000 cycles. When operated at −40 °C, the LIB can keep 67 % capacity of room temperature, which is much better than conventional LIBs.
Co-reporter:Dr. Xiaoli Dong;Hongchuan Yu;Yuanyuan Ma;Junwei Lucas Bao; Donald G. Truhlar; Yonggang Wang; Yongyao Xia
Chemistry - A European Journal 2017 Volume 23(Issue 11) pp:2560-2565
Publication Date(Web):2017/02/21
DOI:10.1002/chem.201700063
AbstractRechargeable batteries with organic electrodes are preferred to those with transition-metal-containing electrodes for their environmental friendliness, and resource availability, but all such batteries reported to date are based on organic electrolytes, which raise concerns of safety and performance. Here an aqueous-electrolyte all-organic rechargeable battery is reported, with a maximum operating voltage of 2.1 V, in which polytriphenylamine (PTPAn) and 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA)-derived polyimide (PNTCDA) serve as cathode and anode material, respectively. A key feature of the design is use of a “water-in-salt” electrolyte to bind “free” water; this impedes the side reaction of water oxidation, thereby enabling excellent reversibility in aqueous solution. The battery can deliver a maximum energy density of 52.8 Wh kg−1, which is close to most of the all-organic batteries with organic electrolytes. The battery exhibits a supercapacitor-like high power of 32 000 W kg−1 and a long cycle life (700 cycles with capacity retention of 85 %), due to the kinetics not being limited by ion diffusion at either electrode.
Co-reporter:Hongchuan Yu, Xiaoli Dong, Ying Pang, Yonggang Wang, Yongyao Xia
Electrochimica Acta 2017 Volume 228(Volume 228) pp:
Publication Date(Web):20 February 2017
DOI:10.1016/j.electacta.2017.01.096
•Hard carbon displays fast Li-storage kinetics which is not controlled by Li+ diffusion.•Spinel cathode exhibits high rate because of three-dimensional Li+-diffusion channels.•LIBs based on micro-sized spinel cathode and hard carbon exhibit high power performance.Power performance of lithium-ion batteries (LIBs) is generally controlled by the Li+ diffusion within crystalline framework of electrode materials, and thus nano-sized electrode materials with shortened diffusion length have been widely used to build high power LIBs. However, the undesired effects from nano-sized electrode materials, such as low tap density, low thermal stability and increased interface also discount the overall performance of LIBs. Accordingly, it is desired to develop high power LIBs with micro-sized electrode materials. Herein, we demonstrate that hard carbon displays fast Li-storage kinetics which is not controlled by Li+ diffusion in the crystalline framework. Furthermore, it is found that micro-sized spinel LiNi0.5Mn1.5O4 and LiMn2O4 have high rate performance, owing to their three-dimensional channels for Li+ diffusion. Finally, the micro-sized spinel LiNi0.5Mn1.5O4 (or Li1.1Mn2O4) and micro-sized hard carbon are used as cathode and anode, respectively, to fabricate the full cells that exhibit supercapacitor-like high power performance. The achieved results point a way to develop high power LIBs besides nano-sizing electrode materials.Download high-res image (194KB)Download full-size imageThe full cells, which are based on micro-sized LiNi0.5Mn1.5O4 (or LiMn2O4) cathode and micro-sized hard carbon anode, exhibit supercapacitor-like high power density.
Co-reporter:Cong Wang;Zhihong Li;Haimei Liu;Yonggang Wang
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 17) pp:8772-8780
Publication Date(Web):2017/08/21
DOI:10.1039/C7NJ01313B
NASICON-structured monoclinic Li3V2(PO4)3 (LVP) is considered as a promising cathode material. However, the disadvantages including low intrinsic electronic conductivity, low ionic conductivity and fast capacity fading at high voltage limit the application of LVP. In order to overcome these drawbacks of LVP and optimize its electrochemical properties, a LVP cathode material is successfully modified for the first time by combining surface N-doped carbon coating with bulk phase K+ doping after the in situ fabrication process in this paper. On the one hand, N-doped carbon coating is able to improve the electron transfer rate at the electrode/electrolyte interface and enhance the electrochemical reaction activity. On the other hand, bulk phase K+ doping can stabilize the crystal structure, limit the structural damage during the Li+ reinsertion process and improve the intrinsic conductivity of LVP. After collaborative modification with N-doped carbon coating and K+ doping, the electron conductivity and Li+ diffusion rate of LVP are improved obviously. Therefore, compared with singly modified LVP samples, the collaborative modified sample reveals better electrochemical properties, especially in the wide potential range of 3–4.8 V vs. Li/Li+. This novel modification method of surface N-doped carbon coating and bulk K+ doping is highly effective and can be widely used to optimize the electrical conductivity of electrode materials for Li-ion batteries.
Co-reporter:Wei Wang;Qunjie Xu;Haimei Liu;Yonggang Wang;Yongyao Xia
Journal of Materials Chemistry A 2017 vol. 5(Issue 18) pp:8440-8450
Publication Date(Web):2017/05/10
DOI:10.1039/C7TA01477E
Na3V2(PO4)3 (NVP) is considered a promising potential electrode material for both the cathode and anode in sodium ion batteries. Recently, flexible sodium ion batteries have attracted increased attention regarding their use as energy storage devices compatible with portable electronics, roll-up displays, implantable devices, and other applications. Here, a feasible strategy was adopted to prepare binder-free, mechanically robust, and paper-like carbon-coated NVP/reduced graphene oxide (NVP@C@rGO) electrodes. Combining the advantages of the large 2D rGO surface and nano-composite sandwich-like microstructure, the as-fabricated feasible NVP@C@rGO electrode demonstrated high reversible capacities and good rate capabilities both as a cathodic and as an anodic material. In addition to the half cell fabricated using a pure Na foil as the counter electrode, an interesting symmetric full cell constructed with NVP@C@rGO//NVP@C@rGO was systemically studied. The optimum design of the full cell exhibited good electrochemical performance, with 1.7 V as the output voltage plateau and a satisfactory capacity of 74.1 mA h g−1 at 0.5C. Up to 10C, this sodium full cell still exhibited stable capacity. Under arbitrary bending conditions, this flexible full cell can still exhibit a stable and safe electrochemical performance. This work may lead to a promising, low cost sodium full cell strategy for next-generation flexible energy storage devices.
Co-reporter:Ziyang Guo, Ye Wang, Yanfang Song, Chao Li, Xiuli Su, Yonggang WangWen-bin Cai, Yongyao Xia
ACS Energy Letters - New in 2016 2017 Volume 2(Issue 1) pp:
Publication Date(Web):December 1, 2016
DOI:10.1021/acsenergylett.6b00566
Fuel cells, Li-ion batteries, and supercapacitors are attracting extensive attention, and it is highly desired to integrate the advantages of these devices into one system. Herein, a multifunction Li–carbon system was designed by using an aqueous–nonaqueous dual electrolyte to combine a nitrogen-doped ordered mesoporous carbon cathode with a metallic lithium anode. It is demonstrated that the nitrogen-doped ordered mesoporous carbon exhibits high performance in various applications of O2 reduction reaction, supercapacitors, and H2 evolution reaction, which makes the Li–carbon system exhibit multifunctionality. When operated in the ambient with O2, the system can work as a Li–air fuel cell or/and rechargeable battery with high energy density. When operated in an environment without O2, the battery can be used as a Li-ion supercapacitor which exhibits long-term cycling stability and improved energy performance. Finally, this cell can also be applied as a Li–water fuel cell for H2 evolution.
Co-reporter:Zhaowei Guo, Yang Zhao, Yuxue Ding, Xiaoli Dong, ... Yonggang Wang
Chem 2017 Volume 3, Issue 2(Volume 3, Issue 2) pp:
Publication Date(Web):10 August 2017
DOI:10.1016/j.chempr.2017.05.004
•Flexible aqueous belt- and fiber-shaped SIBs with high safety are fabricated•Normal saline and cell-culture medium are used directly as electrolytes for SIBs•Fiber-shaped SIBs exhibit an electrochemical deoxygenation functionThe development of wearable and implantable electrical devices has been in great demand recently. However, most existing energy storage systems are based on strong corrosive or toxic electrolytes, posing a huge safety hazard as a result of solution leakage. Here, we have developed a family of safe and flexible belt- and fiber-shaped aqueous sodium-ion batteries (SIBs) by using various Na+-containing aqueous electrolytes, including Na2SO4 solution, normal saline, and cell-culture medium. The resulting SIBs exhibit high flexibility and excellent electrochemical performance and can be safely applied in wearable electronics. Flexible SIBs with normal saline or cell-culture medium as the electrolyte showed excellent performance, indicating potential application in implantable electronic devices. In addition, the fiber-shaped electrode in normal saline or cell-culture medium electrolyte can consume O2 and change the pH, implying promising application in biological and medical investigations.Flexible energy storage devices are attracting extensive attention, but most of the reported flexible batteries and supercapacitors use either strong acid or base or toxic flammable organic solutions as electrolytes, which pose potential safety issues when worn by humans or implanted into the body. Here, we present a highly safe family of flexible sodium-ion batteries (SIBs) based on a Na0.44MnO2 cathode, a nano-sized NaTi2(PO4)3@C anode, and various aqueous electrolytes containing Na+. The resulting belt- and fiber-shaped aqueous SIBs exhibit high volumetric energy and power density, high flexibility, and long life and thus can be safely applied in wearable electronic devices. When normal saline or cell-culture medium is used as the electrolyte, these SIBs can still work well, indicating potential application in implantable electronic devices. The fiber-shaped electrodes in Na+-containing aqueous electrolytes exhibit an electrochemical deoxygenation function, which could be applied in biological and medical fields.Download high-res image (196KB)Download full-size image
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:Shouyi Yuan;Junwei Lucas Bao;Lina Wang;Yongyao Xia;Donald G. Truhlar;Yonggang Wang
Advanced Energy Materials 2016 Volume 6( Issue 5) pp:
Publication Date(Web):
DOI:10.1002/aenm.201501733
Co-reporter:Ziyang Guo, Chao Li, Wangyu Li, Hua Guo, Xiuli Su, Ping He, Yonggang Wang and Yongyao Xia
Journal of Materials Chemistry A 2016 vol. 4(Issue 17) pp:6282-6289
Publication Date(Web):04 Apr 2016
DOI:10.1039/C6TA02030E
We synthesized RuO2-coated ordered mesoporous carbon nanofiber arrays (MCNAs) through a natural crab shell template, as a bifunctional catalyst for Zn–air batteries. The uniform RuO2-coating layer and ordered mesopores ensure high electrical conductivity and facilitate ion diffusion, respectively, which provide enough active sites for the ORR/OER; the macro-sized void spaces between carbon nanofibers not only play the role of a buffer in the reactions, but also facilitate oxygen transfer; the uniform RuO2-coating layer ensures catalytic activity and selectivity for catalyzing reactions (ORR and OER), especially the OER. As a result, this Zn–air battery exhibits much improved electrochemical performance, including relatively low overpotentials, long cycle life and superior rate capability.
Co-reporter:Chao Li, Ziyang Guo, Ying Pang, Yunhe Sun, Xiuli Su, Yonggang Wang, and Yongyao Xia
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 46) pp:31638
Publication Date(Web):October 31, 2016
DOI:10.1021/acsami.6b10115
The Li–O2 battery is receiving much recent attention because of its superhigh theoretical energy density. However, its performance is limited by the irreversible formation/decomposition of Li2O2 on the cathode and the undesired electrolyte decomposition. In this work, low-cost three-dimensional ordered macroporous (3DOM) FePO4 is synthesized by using polystyrene (PS) spheres template in a facile experimental condition and applied as a high-efficiency catalyst for rechargeable Li–O2 batteries, including good rate performance, high specific capacity, and perfect cycling stability. The superior performances can be attributed to the unique structure of 3DOM FePO4 cathodes, which can provide an efficient buffer space for O2/Li2O2 conversion. In addition, it is demonstrated that the Li+ intercalation/deintercalation behavior of 3DOM FePO4 in ether-based electrolyte can contribute to capacity for Li–O2 batteries over cycling. As a result, when there is no O2 in the environment, the Li–O2 cell can also be operated as a rechargeable Li-FePO4 cell with a perfect cycle capability.Keywords: FePO4; high cycling stability; Li-FePO4 battery; Li−O2 battery; three-dimensional ordered macroporous
Co-reporter:Wei Shen, Hui Li, Ziyang Guo, Cong Wang, Zhihong Li, Qunjie Xu, Haimei Liu, Yonggang Wang, and Yongyao Xia
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 24) pp:15341-15351
Publication Date(Web):June 3, 2016
DOI:10.1021/acsami.6b03410
An advanced cathode material, nitrogen-doped carbon-coated Na3V2(PO4)3 hybriding with multiwalled carbon nanotubes (CNTs) composite, namely double-nanocarbon synergistically modified Na3V2(PO4)3 of sodium ion battery, was fabricated through a simple sol–gel approach. According to the systemical analysis of experimental results on this composite structure, it is found that N-doping not only increases Na-ion migration velocity across the carbon-coated layer but also improves the electric conductivity of the carbon layer. More importantly, the CNTs 3D conducting network could significantly accelerate the electron transport between multiple particles of Na3V2(PO4)3, due to the intimate contacts between active materials and CNTs. Consenquently, the electrochemical properties of this double-nanocarbon-modified Na3V2(PO4)3 are significantly enhanced, especially the high-rate capability and long cycle life. For instance, its initial capacity of 94.5 mAh g–1 at 0.2 C decreases to 70 mAh g–1 at 70 C, and the capacity retention is 74%. Moreover, when dischage rate increases to a higher 30 C, the capacity retention is still as high as 87% after 300 cycles.
Co-reporter:Long Chen, Xiaoli Dong, Fei Wang, Yonggang Wang and Yongyao Xia
Chemical Communications 2016 vol. 52(Issue 15) pp:3147-3150
Publication Date(Web):11 Jan 2016
DOI:10.1039/C5CC09642A
A base–acid hybrid electrolytic system with a low onset voltage of 0.78 V for water electrolysis was developed by using a ceramic Li-ion exchange membrane to separate the oxygen-evolving reaction (OER) in a basic electrolyte solution containing the Li-ion and hydrogen-evolving reaction (HER) in an acidic electrolyte solution.
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:Dr. Xiaoli Dong;Long Chen;Xiuli Su; Yonggang Wang; Yongyao Xia
Angewandte Chemie International Edition 2016 Volume 55( Issue 26) pp:7474-7477
Publication Date(Web):
DOI:10.1002/anie.201602766
Abstract
A flexible and wearable aqueous lithium-ion battery is introduced based on spinel Li1.1Mn2O4 cathode and a carbon-coated NASICON-type LiTi2(PO4)3 anode (NASICON=sodium-ion super ionic conductor). Energy densities of 63 Wh kg−1 or 124 mWh cm−3 and power densities of 3 275 W kg−1 or 11.1 W cm−3 can be obtained, which are seven times larger than the largest reported till now. The full cell can keep its capacity without significant loss under different bending states, which shows excellent flexibility. Furthermore, two such flexible cells in series with an operation voltage of 4 V can be compatible with current nonaqueous Li-ion batteries. Therefore, such a flexible cell can potentially be put into practical applications for wearable electronics. In addition, a self-chargeable unit is realized by integrating a single flexible aqueous Li-ion battery with a commercial flexible solar cell, which may facilitate the long-time outdoor operation of flexible and wearable electronic devices.
Co-reporter:Dr. Xiaoli Dong;Long Chen;Xiuli Su; Yonggang Wang; Yongyao Xia
Angewandte Chemie 2016 Volume 128( Issue 26) pp:7600-7603
Publication Date(Web):
DOI:10.1002/ange.201602766
Abstract
A flexible and wearable aqueous lithium-ion battery is introduced based on spinel Li1.1Mn2O4 cathode and a carbon-coated NASICON-type LiTi2(PO4)3 anode (NASICON=sodium-ion super ionic conductor). Energy densities of 63 Wh kg−1 or 124 mWh cm−3 and power densities of 3 275 W kg−1 or 11.1 W cm−3 can be obtained, which are seven times larger than the largest reported till now. The full cell can keep its capacity without significant loss under different bending states, which shows excellent flexibility. Furthermore, two such flexible cells in series with an operation voltage of 4 V can be compatible with current nonaqueous Li-ion batteries. Therefore, such a flexible cell can potentially be put into practical applications for wearable electronics. In addition, a self-chargeable unit is realized by integrating a single flexible aqueous Li-ion battery with a commercial flexible solar cell, which may facilitate the long-time outdoor operation of flexible and wearable electronic devices.
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:Wei Shen;Cong Wang;Qunjie Xu;Haimei Liu;Yonggang Wang
Advanced Energy Materials 2015 Volume 5( Issue 1) pp:
Publication Date(Web):
DOI:10.1002/aenm.201400982
A nitrogen-doped, carbon-coated Na3V2(PO4)3 cathode material is synthesized and the formation of doping type of nitrogen-doped in carbon coating layer is systemically investigated. Three different carbon-nitrogen species: pyridinic N, pyrrolic N, and quaternary N are identified. The most important finding is that different carbon-nitrogen species in the carbon layer have different impacts on the improvement of the electrochemical properties of Na3V2(PO4)3. Pyridinic N and pyrrolic N significantly increase the electronic conductivity and create numerous extrinsic defects and active sites. Quaternary N only increases the electronic conductivity without creating extrinsic defects. Therefore, it is unexpectedly demonstrated that the Na3V2(PO4)3/C+N, in which with minimize content of quaternary N or exist most extrinsic defects, exhibits the best electrochemical performance, particularly the rate performance and cycling stability. For example, when the discharging rate increased from 0.2 C to 5 C, its capacity of 101.9 mAh g−1 decays to 84.3 mAh g−1 and an amazing capacity retention of 83% is achieved. Moreover, even at higher current density of 5 C, an excellent capacity retention of 93% is maintained even after 100 cycles.
Co-reporter:Ziyang Guo, Chao Li, Jingyuan Liu, Xiuli Su, Yonggang Wang and Yongyao Xia
Journal of Materials Chemistry A 2015 vol. 3(Issue 42) pp:21123-21132
Publication Date(Web):11 Sep 2015
DOI:10.1039/C5TA06850A
Porous carbon, which is the most widely used cathode material ever for Li–O2 batteries, is found to decompose in the charging process, promote electrolyte decomposition, and react with the discharge product. Carbon-free cathodes thus become critical for Li–O2 batteries, but generally exhibit low capacity and poor rate because of their high density and insufficient pore characteristic. Herein, we present a simple method to prepare a core–shell-structured TiO2(B) nanofiber@porous RuO2 composite, which is used as a carbon-free catalyst for Li–O2 batteries. The RuO2 coating layer replicates the structure of TiO2 nanofibers to form a one-dimensional RuO2 shell with a typical hierarchical mesoporous/macroporous structure. Besides the reduced undesired decomposition, the abundant porous structure and inherent high conductivity of the RuO2 coating layer also increase the specific capacity, efficiency, rate ability and cycle life. With a high mass loading of 2.5 mg cm−2 on the cathode, the Li–O2 battery shows a performance superior to previous reports, including high capacity (800 mA h g−1 at a current density of 0.125 mA cm−2 or 50 mA g−1) with a very high energy efficiency of >82.5%, good rate (500 mA h g−1 at a current density of 0.5 mA cm−2 or 200 mA g−1) and long-life (80 cycles at a fixed capacity of 300 mA h g−1). It is also demonstrated that the lithiation/de-lithiation of RuO2 can contribute capacity over the charge/discharge process, indicating that this battery can be operated as a rechargeable RuO2/Li battery without O2 in the environment.
Co-reporter:Wei Shen, Hui Li, Cong Wang, Zhihong Li, Qunjie Xu, Haimei Liu and Yonggang Wang
Journal of Materials Chemistry A 2015 vol. 3(Issue 29) pp:15190-15201
Publication Date(Web):16 Jun 2015
DOI:10.1039/C5TA03519H
Boron-doped carbon coating is initially used to improve the electrochemical performance of Na3V2(PO4)3 cathode materials of sodium-ion batteries. Based on the precise analysis of Raman spectroscopy, electrochemical impedance spectroscopy and X-ray photoemission spectroscopy, it is found that there are four different B-doping species (B4C, BC3, BC2O and BCO2) in various boron-doped carbon coated Na3V2(PO4)3 samples; moreover, different B-doping species in the carbon coated layer have different impacts on the improvement of the electrochemical performance of Na3V2(PO4)3. Compared to lithium-ion batteries, the mechanism of B-doped carbon coating for the improvement of the electrochemical performance in sodium-ion batteries is different. Due to the introduction of the O atom in the carbon coated layer, BC2O and BCO2 significantly increase numerous extrinsic defects and active sites, which could significantly accelerate Na+ transport in the carbon layer. Therefore, it is unexpectedly demonstrated that Na3V2(PO4)3/C + B, which consists of the largest total amount of BC2O + BCO2, exhibits the best electrochemical performance, particularly high-rate performance and cycling stability. As an example, when the discharging rate increases from 0.2 C to 5 C, it delivers 95.8 mA h g−1 to 90.3 mA h g−1 and an amazing capacity retention of 94% is achieved.
Co-reporter:Cong Wang, Ziyang Guo, Wei Shen, Aili Zhang, Qunjie Xu, Haimei Liu and Yonggang Wang
Journal of Materials Chemistry A 2015 vol. 3(Issue 11) pp:6064-6072
Publication Date(Web):02 Feb 2015
DOI:10.1039/C5TA00323G
In an optimized modification approach, sulfur-doped carbon coating is initially applied to improve the electrochemical properties of Li3V2(PO4)3 cathode material. The existence and formation of sulfur doping in the carbon-coating layer was confirmed by XPS and EDX mapping, and furthermore it was found that various carbon–sulfur species had a significant impact on improving the electronic conductivity and defect level of the surface carbon layer of Li3V2(PO4)3 composites. Therefore, we unexpectedly demonstrated that, when compared with bare Li3V2(PO4)3/C, sulfur-doped carbon-coated Li3V2(PO4)3 exhibits a more outstanding electrochemical performance, especially with regard to the cycle capability and rate stability. For instance, when the discharge rate was increased from 0.5 C to 50 C, the capacity of Li3V2(PO4)3/C + S only decayed from 122.1 mA h g−1 to 106.4 mA h g−1, indicating an amazing capacity retention of 87%. This novel modification method of S-doped carbon coating is highly effective and could be widely used to optimize the electric conductivity of electrode materials for Li-ion batteries.
Co-reporter:Ji-Shi Wei, Hui Ding, Yong-Gang Wang, and Huan-Ming Xiong
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 10) pp:5811
Publication Date(Web):March 4, 2015
DOI:10.1021/am508864c
A type of hierarchical porous carbon material was prepared using a Schiff-base network as the precursor and ZnCl2 as the activation agent, and their electrochemical performances were investigated in acid and alkaline aqueous solutions, respectively. The as-prepared materials have high surface areas, appropriate distributions of hierarchical pore sizes, and various forms of nitrogen/oxygen derivatives. These structural advantages guarantee the outstanding performances of such carbon materials as electrodes for supercapacitors, which include high specific capacitances, fast current responses, and high cycling stabilities.Keywords: carbon materials; dope; porous; Schiff-base networks; supercapacitors
Co-reporter:Ziyang Guo, XiaoLi Dong, Yonggang Wang and Yongyao Xia
Chemical Communications 2015 vol. 51(Issue 4) pp:676-678
Publication Date(Web):14 Nov 2014
DOI:10.1039/C4CC07315K
A lithiated Al–carbon composite electrode with a uniform SEI film was prepared by an electrochemical method, and was then coupled with an O2 catalytic electrode to form a rechargeable Li–O2 (or air) battery with a LixAl–C anode.
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:Yimeng Xu, Wei Shen, Cong Wang, Aili Zhang, Qunjie Xu, Haimei Liu, Yonggang Wang, Yongyao Xia
Electrochimica Acta 2015 Volume 167() pp:340-347
Publication Date(Web):10 June 2015
DOI:10.1016/j.electacta.2015.03.170
Li2FeSiO4 nanoparticles are successfully synthesized via hydrothermal approach, with the hydrothermal process monitored in detail. Structural characterizations by XRD, FTIR, SEM and HRTEM measurements reveal that the Li2FeSiO4 nanoparticles have a high crystalline degree and monodisperse nanoparticle shape with a size around of 50–200 nm. To further improve the electronic conductivity, the Li2FeSiO4 nanoparticles are coated by a carbon layer using in suit polymerization of dopamine. Moreover, the effect of carbon content for electrochemical performance of Li2FeSiO4/C is systemically investigated, and as a result, the composite with a ratio of Li2FeSiO4 and dopamine of 3:1 demonstrate the best electrochemical performance with a discharge specific capacity of 148 mA h g−1 at a rate of 0.1 C at room temperature. Furthermore, the electrochemical performance of Li2FeSiO4/C at high temperature of 55 °C is also investigated, and it also exhibits a good performance with a discharge specific capacity of 240 mA h g−1at a current rate of 0.2 C.
Co-reporter:Aili Zhang, Cong Wang, Qunjie Xu, Haimei Liu, Yonggang Wang and Yongyao Xia
RSC Advances 2015 vol. 5(Issue 33) pp:26017-26026
Publication Date(Web):02 Mar 2015
DOI:10.1039/C5RA00103J
A three-dimensional (3D) porous hybrid aerogel with a robust interconnected network, which is constructed from cobalt–aluminum layered double hydroxide (Co–Al LDH) nanosheets and graphene, is reported here. The unique character of this hybrid aerogel is that the 3D graphene aerogel (GA) skeleton is incorporated with two-dimensional (2D) Co–Al LDH nanosheets to assemble macroscopic graphene monoliths. Furthermore, the 3D GA in the hybrid aerogel is a scaffold and support for the dispersion of the Co–Al LDH nanosheets, resulting in a relatively loose and open structure within the electrode matrix. When used as a cathode material for supercapacitors, the as-obtained porous Co–Al LDH/graphene hybrid aerogel (Co–Al LDH/GHA) exhibits favorable capacitance and excellent cycling performance, and demonstrates a maximum specific capacitance of 640 F g−1 at a low current density of 1 A g−1. This remains at 530 F g−1 when the current density is increased to 10 A g−1, and even remains at 305 F g−1 at a much higher current density of 20 A g−1. The capacitance keeps at around 97% after 10000 cycles, demonstrating that the hybrid aerogel has excellent high-current capacitive properties. The enhanced high-current capacitance of this composite benefits from its unique nano-scaled Co–Al LDH with a short diffusion pathway and the excellent electrical conductivity of 3D GA.
Co-reporter:Yifan Xu;Ye Zhang;Ziyang Guo;Jing Ren; Yonggang Wang; Huisheng Peng
Angewandte Chemie 2015 Volume 127( Issue 51) pp:15610-15614
Publication Date(Web):
DOI:10.1002/ange.201508848
Abstract
The fabrication of flexible, stretchable and rechargeable devices with a high energy density is critical for next-generation electronics. Herein, fiber-shaped Zn–air batteries, are realized for the first time by designing aligned, cross-stacked and porous carbon nanotube sheets simultaneously that behave as a gas diffusion layer, a catalyst layer, and a current collector. The combined remarkable electronic and mechanical properties of the aligned carbon nanotube sheets endow good electrochemical properties. They display excellent discharge and charge performances at a high current density of 2 A g−1. They are also flexible and stretchable, which is particularly promising to power portable and wearable electronic devices.
Co-reporter:Yifan Xu;Ye Zhang;Ziyang Guo;Jing Ren; Yonggang Wang; Huisheng Peng
Angewandte Chemie International Edition 2015 Volume 54( Issue 51) pp:15390-15394
Publication Date(Web):
DOI:10.1002/anie.201508848
Abstract
The fabrication of flexible, stretchable and rechargeable devices with a high energy density is critical for next-generation electronics. Herein, fiber-shaped Zn–air batteries, are realized for the first time by designing aligned, cross-stacked and porous carbon nanotube sheets simultaneously that behave as a gas diffusion layer, a catalyst layer, and a current collector. The combined remarkable electronic and mechanical properties of the aligned carbon nanotube sheets endow good electrochemical properties. They display excellent discharge and charge performances at a high current density of 2 A g−1. They are also flexible and stretchable, which is particularly promising to power portable and wearable electronic devices.
Co-reporter:Doufeng Wu;Ziyang Guo;Xinbo Yin;Qingqing Pang;Binbin Tu;Lijuan Zhang;Qiaowei Li
Advanced Materials 2014 Volume 26( Issue 20) pp:3258-3262
Publication Date(Web):
DOI:10.1002/adma.201305492
Co-reporter:Cong Wang;Ziyang Guo;Wei Shen;Qunjie Xu;Haimei Liu;Yonggang Wang
Advanced Functional Materials 2014 Volume 24( Issue 35) pp:5511-5521
Publication Date(Web):
DOI:10.1002/adfm.201401006
An evolutionary modification approach, boron doped carbon coating, is initially used to improve the electrochemical properties of electrode materials of lithium-ion batteries, such as Li3V2(PO4)3, and demonstrates apparent and significant modification effects. Based on the precise analysis of X-ray photoemission spectroscopy results, Raman spectra, and electrochemical impedance spectroscopy results for various B-doped carbon coated Li3V2(PO4)3 samples, it is found that, among various B-doping types (B4C, BC3, BC2O and BCO2), the graphite-like BC3 dopant species plays a huge role on improving the electronic conductivity and electrochemical activity of the carbon coated layer on Li3V2(PO4)3 surface. As a result, when compared with the bare carbon coated Li3V2(PO4)3, the electrochemical performances of the B-doped carbon coated Li3V2(PO4)3 electrode with a moderate doping amount are greatly improved. For example, when cycled under 1 C and 20 C in the potential range of 3.0–4.3 V, this sample shows an initial capacity of 122.5 and 118.4 mAh g−1, respectively; after 200 cycles, nearly 100% of the initial capacity is retained. Moreover, the modification effects of B-doped carbon coating approach are further validated on Li4Ti5O12 anode material.
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:Ziyang Guo, Xiaoli Dong, Shouyi Yuan, Yonggang Wang, Yongyao Xia
Journal of Power Sources 2014 Volume 264() pp:1-7
Publication Date(Web):15 October 2014
DOI:10.1016/j.jpowsour.2014.04.079
•Humidity is a strong capacity enhancer for the Li–O2 batteries, but limits the cyclic ability and rate performance.•Humidity affects the Li2O2/O2 conversion, LiCO3/CO2 conversion and LiOH formation over charge/discharge cycle.•Humidity varying results in different morphologies of the discharge products.In this work, we compare the performance of Li–O2 batteries in pure/dry O2, pure O2 with a relative humidity (RH) of 15% and ambient air with an RH of 50%, and analyze the ambient humidity effect on the reactions in the carbon-based catalytic electrode. Electrochemical investigation indicates that discharge capacities of Li–O2 batteries increased with growth of RH value, but cyclic ability and rate performance are influenced in an opposite way. Ex-situ X-ray diffraction (XRD), Fourier transform-infrared spectrophotometer (FT-IR) and scanning electron microscope (SEM) investigations suggest that ambient humidity affects not only the Li2O2/O2 conversion, LiCO3/CO2 conversion and LiOH formation but also the morphology of discharge products in porous catalytic electrode over charge/discharge cycle. These results may be important for developing Li–air battery.
Co-reporter:Jing Ren;Ye Zhang;Wenyu Bai;Xuli Chen;Zhitao Zhang;Xin Fang;Wei Weng;Dr. Yonggang Wang; Huisheng Peng
Angewandte Chemie International Edition 2014 Volume 53( Issue 30) pp:7864-7869
Publication Date(Web):
DOI:10.1002/anie.201402388
Abstract
A stretchable wire-shaped lithium-ion battery is produced from two aligned multi-walled carbon nanotube/lithium oxide composite yarns as the anode and cathode without extra current collectors and binders. The two composite yarns can be well paired to obtain a safe battery with superior electrochemical properties, such as energy densities of 27 Wh kg−1 or 17.7 mWh cm−3 and power densities of 880 W kg−1 or 0.56 W cm−3, which are an order of magnitude higher than the densities reported for lithium thin-film batteries. These wire-shaped batteries are flexible and light, and 97 % of their capacity was maintained after 1000 bending cycles. They are also very elastic as they are based on a modified spring structure, and 84 % of the capacity was maintained after stretching for 200 cycles at a strain of 100 %. Furthermore, these novel wire-shaped batteries have been woven into lightweight, flexible, and stretchable battery textiles, which reveals possible large-scale applications.
Co-reporter:Jing Ren;Ye Zhang;Wenyu Bai;Xuli Chen;Zhitao Zhang;Xin Fang;Wei Weng;Dr. Yonggang Wang; Huisheng Peng
Angewandte Chemie International Edition 2014 Volume 53( Issue 30) pp:
Publication Date(Web):
DOI:10.1002/anie.201405394
Co-reporter:Jing Ren;Ye Zhang;Wenyu Bai;Xuli Chen;Zhitao Zhang;Xin Fang;Wei Weng;Dr. Yonggang Wang; Huisheng Peng
Angewandte Chemie 2014 Volume 126( Issue 30) pp:7998-8003
Publication Date(Web):
DOI:10.1002/ange.201402388
Abstract
A stretchable wire-shaped lithium-ion battery is produced from two aligned multi-walled carbon nanotube/lithium oxide composite yarns as the anode and cathode without extra current collectors and binders. The two composite yarns can be well paired to obtain a safe battery with superior electrochemical properties, such as energy densities of 27 Wh kg−1 or 17.7 mWh cm−3 and power densities of 880 W kg−1 or 0.56 W cm−3, which are an order of magnitude higher than the densities reported for lithium thin-film batteries. These wire-shaped batteries are flexible and light, and 97 % of their capacity was maintained after 1000 bending cycles. They are also very elastic as they are based on a modified spring structure, and 84 % of the capacity was maintained after stretching for 200 cycles at a strain of 100 %. Furthermore, these novel wire-shaped batteries have been woven into lightweight, flexible, and stretchable battery textiles, which reveals possible large-scale applications.
Co-reporter:Jing Ren;Ye Zhang;Wenyu Bai;Xuli Chen;Zhitao Zhang;Xin Fang;Wei Weng;Dr. Yonggang Wang; Huisheng Peng
Angewandte Chemie 2014 Volume 126( Issue 30) pp:
Publication Date(Web):
DOI:10.1002/ange.201405394
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:Jing Ren;Li Li;Chen Chen;Xuli Chen;Zhenbo Cai;Longbin Qiu;Yonggang Wang;Xingrong Zhu;Huisheng Peng
Advanced Materials 2013 Volume 25( Issue 8) pp:
Publication Date(Web):
DOI:10.1002/adma.201370048
Co-reporter:Jing Ren;Li Li;Chen Chen;Xuli Chen;Zhenbo Cai;Longbin Qiu;Yonggang Wang;Xingrong Zhu;Huisheng Peng
Advanced Materials 2013 Volume 25( Issue 8) pp:1155-1159
Publication Date(Web):
DOI:10.1002/adma.201203445
Co-reporter:Yonggang Wang;Ziyang Guo ;Yongyao Xia
Advanced Energy Materials 2013 Volume 3( Issue 6) pp:713-717
Publication Date(Web):
DOI:10.1002/aenm.201200975
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:Long Chen, Ziyang Guo, Yongyao Xia and Yonggang Wang
Chemical Communications 2013 vol. 49(Issue 22) pp:2204-2206
Publication Date(Web):23 Jan 2013
DOI:10.1039/C3CC00064H
Based on an acidic–alkaline double electrolyte, we designed and fabricated a novel Zn/KMnO4 aqueous cell with a high operating voltage of 2.8 V. The theoretical energy density of this aqueous cell is even compatible with organic electrolyte-based lithium batteries.
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: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: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: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:Long Chen, Xiaoli Dong, Fei Wang, Yonggang Wang and Yongyao Xia
Chemical Communications 2016 - vol. 52(Issue 15) pp:NaN3150-3150
Publication Date(Web):2016/01/11
DOI:10.1039/C5CC09642A
A base–acid hybrid electrolytic system with a low onset voltage of 0.78 V for water electrolysis was developed by using a ceramic Li-ion exchange membrane to separate the oxygen-evolving reaction (OER) in a basic electrolyte solution containing the Li-ion and hydrogen-evolving reaction (HER) in an acidic electrolyte solution.
Co-reporter:Ziyang Guo, XiaoLi Dong, Yonggang Wang and Yongyao Xia
Chemical Communications 2015 - vol. 51(Issue 4) pp:NaN678-678
Publication Date(Web):2014/11/14
DOI:10.1039/C4CC07315K
A lithiated Al–carbon composite electrode with a uniform SEI film was prepared by an electrochemical method, and was then coupled with an O2 catalytic electrode to form a rechargeable Li–O2 (or air) battery with a LixAl–C anode.
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:Long Chen, Ziyang Guo, Yongyao Xia and Yonggang Wang
Chemical Communications 2013 - vol. 49(Issue 22) pp:NaN2206-2206
Publication Date(Web):2013/01/23
DOI:10.1039/C3CC00064H
Based on an acidic–alkaline double electrolyte, we designed and fabricated a novel Zn/KMnO4 aqueous cell with a high operating voltage of 2.8 V. The theoretical energy density of this aqueous cell is even compatible with organic electrolyte-based lithium batteries.
Co-reporter:Wei Shen, Hui Li, Cong Wang, Zhihong Li, Qunjie Xu, Haimei Liu and Yonggang Wang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 29) pp:NaN15201-15201
Publication Date(Web):2015/06/16
DOI:10.1039/C5TA03519H
Boron-doped carbon coating is initially used to improve the electrochemical performance of Na3V2(PO4)3 cathode materials of sodium-ion batteries. Based on the precise analysis of Raman spectroscopy, electrochemical impedance spectroscopy and X-ray photoemission spectroscopy, it is found that there are four different B-doping species (B4C, BC3, BC2O and BCO2) in various boron-doped carbon coated Na3V2(PO4)3 samples; moreover, different B-doping species in the carbon coated layer have different impacts on the improvement of the electrochemical performance of Na3V2(PO4)3. Compared to lithium-ion batteries, the mechanism of B-doped carbon coating for the improvement of the electrochemical performance in sodium-ion batteries is different. Due to the introduction of the O atom in the carbon coated layer, BC2O and BCO2 significantly increase numerous extrinsic defects and active sites, which could significantly accelerate Na+ transport in the carbon layer. Therefore, it is unexpectedly demonstrated that Na3V2(PO4)3/C + B, which consists of the largest total amount of BC2O + BCO2, exhibits the best electrochemical performance, particularly high-rate performance and cycling stability. As an example, when the discharging rate increases from 0.2 C to 5 C, it delivers 95.8 mA h g−1 to 90.3 mA h g−1 and an amazing capacity retention of 94% is achieved.
Co-reporter:Ziyang Guo, Chao Li, Jingyuan Liu, Xiuli Su, Yonggang Wang and Yongyao Xia
Journal of Materials Chemistry A 2015 - vol. 3(Issue 42) pp:NaN21132-21132
Publication Date(Web):2015/09/11
DOI:10.1039/C5TA06850A
Porous carbon, which is the most widely used cathode material ever for Li–O2 batteries, is found to decompose in the charging process, promote electrolyte decomposition, and react with the discharge product. Carbon-free cathodes thus become critical for Li–O2 batteries, but generally exhibit low capacity and poor rate because of their high density and insufficient pore characteristic. Herein, we present a simple method to prepare a core–shell-structured TiO2(B) nanofiber@porous RuO2 composite, which is used as a carbon-free catalyst for Li–O2 batteries. The RuO2 coating layer replicates the structure of TiO2 nanofibers to form a one-dimensional RuO2 shell with a typical hierarchical mesoporous/macroporous structure. Besides the reduced undesired decomposition, the abundant porous structure and inherent high conductivity of the RuO2 coating layer also increase the specific capacity, efficiency, rate ability and cycle life. With a high mass loading of 2.5 mg cm−2 on the cathode, the Li–O2 battery shows a performance superior to previous reports, including high capacity (800 mA h g−1 at a current density of 0.125 mA cm−2 or 50 mA g−1) with a very high energy efficiency of >82.5%, good rate (500 mA h g−1 at a current density of 0.5 mA cm−2 or 200 mA g−1) and long-life (80 cycles at a fixed capacity of 300 mA h g−1). It is also demonstrated that the lithiation/de-lithiation of RuO2 can contribute capacity over the charge/discharge process, indicating that this battery can be operated as a rechargeable RuO2/Li battery without O2 in the environment.
Co-reporter:Cong Wang, Ziyang Guo, Wei Shen, Aili Zhang, Qunjie Xu, Haimei Liu and Yonggang Wang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 11) pp:NaN6072-6072
Publication Date(Web):2015/02/02
DOI:10.1039/C5TA00323G
In an optimized modification approach, sulfur-doped carbon coating is initially applied to improve the electrochemical properties of Li3V2(PO4)3 cathode material. The existence and formation of sulfur doping in the carbon-coating layer was confirmed by XPS and EDX mapping, and furthermore it was found that various carbon–sulfur species had a significant impact on improving the electronic conductivity and defect level of the surface carbon layer of Li3V2(PO4)3 composites. Therefore, we unexpectedly demonstrated that, when compared with bare Li3V2(PO4)3/C, sulfur-doped carbon-coated Li3V2(PO4)3 exhibits a more outstanding electrochemical performance, especially with regard to the cycle capability and rate stability. For instance, when the discharge rate was increased from 0.5 C to 50 C, the capacity of Li3V2(PO4)3/C + S only decayed from 122.1 mA h g−1 to 106.4 mA h g−1, indicating an amazing capacity retention of 87%. This novel modification method of S-doped carbon coating is highly effective and could be widely used to optimize the electric conductivity of electrode materials for Li-ion batteries.
Co-reporter:Ziyang Guo, Chao Li, Wangyu Li, Hua Guo, Xiuli Su, Ping He, Yonggang Wang and Yongyao Xia
Journal of Materials Chemistry A 2016 - vol. 4(Issue 17) pp:NaN6289-6289
Publication Date(Web):2016/04/04
DOI:10.1039/C6TA02030E
We synthesized RuO2-coated ordered mesoporous carbon nanofiber arrays (MCNAs) through a natural crab shell template, as a bifunctional catalyst for Zn–air batteries. The uniform RuO2-coating layer and ordered mesopores ensure high electrical conductivity and facilitate ion diffusion, respectively, which provide enough active sites for the ORR/OER; the macro-sized void spaces between carbon nanofibers not only play the role of a buffer in the reactions, but also facilitate oxygen transfer; the uniform RuO2-coating layer ensures catalytic activity and selectivity for catalyzing reactions (ORR and OER), especially the OER. As a result, this Zn–air battery exhibits much improved electrochemical performance, including relatively low overpotentials, long cycle life and superior rate capability.
Co-reporter:Zhihong Li, Wei Shen, Cong Wang, Qunjie Xu, Haimei Liu, Yonggang Wang and Yongyao Xia
Journal of Materials Chemistry A 2016 - vol. 4(Issue 43) pp:NaN17120-17120
Publication Date(Web):2016/10/06
DOI:10.1039/C6TA08416H
Flexible energy-storage devices have attracted much attention in recent years due to their promising application in wearable sensors, smart electronics, and implantable medical devices. Novel electrode architectures and new systems are considered to be the best choices to improve the electrochemical performance. Here, ultra-long Na2Ti3O7 nanowires (L-NTO NWs) with a length of more than 100 μm and a width of 100–200 nm were grown on a carbon cloth (CC) substrate by a one-pot hydrothermal method. The porous structure formed by the interwoven nanowires enables sufficient electrode/electrolyte interactions and fast electron transportation. Meanwhile, the unique 3D architecture can maximize the active interface between the nanowires and electrolyte, enabling a long lifetime, large capacity, and a high coulombic efficiency. As a binder-free flexible electrode for sodium-ion batteries, this novel L-NTO NW@CC anode electrode demonstrates a high specific capacity of 170.3 mA h g−1 (close to 100% of the theoretical capacity), excellent cyclability with a capacity retention of over 96% after 200 cycles at 2C, and—following cycling at a current density of 3C—a discharge capacity of 100.6 mA h g−1 after 300 cycles. This work is expected to provide a feasible and effective approach to design flexible electrodes with a long lifetime and large capacity for sodium-ion batteries.
Co-reporter:Wei Wang, Qunjie Xu, Haimei Liu, Yonggang Wang and Yongyao Xia
Journal of Materials Chemistry A 2017 - vol. 5(Issue 18) pp:NaN8450-8450
Publication Date(Web):2017/04/04
DOI:10.1039/C7TA01477E
Na3V2(PO4)3 (NVP) is considered a promising potential electrode material for both the cathode and anode in sodium ion batteries. Recently, flexible sodium ion batteries have attracted increased attention regarding their use as energy storage devices compatible with portable electronics, roll-up displays, implantable devices, and other applications. Here, a feasible strategy was adopted to prepare binder-free, mechanically robust, and paper-like carbon-coated NVP/reduced graphene oxide (NVP@C@rGO) electrodes. Combining the advantages of the large 2D rGO surface and nano-composite sandwich-like microstructure, the as-fabricated feasible NVP@C@rGO electrode demonstrated high reversible capacities and good rate capabilities both as a cathodic and as an anodic material. In addition to the half cell fabricated using a pure Na foil as the counter electrode, an interesting symmetric full cell constructed with NVP@C@rGO//NVP@C@rGO was systemically studied. The optimum design of the full cell exhibited good electrochemical performance, with 1.7 V as the output voltage plateau and a satisfactory capacity of 74.1 mA h g−1 at 0.5C. Up to 10C, this sodium full cell still exhibited stable capacity. Under arbitrary bending conditions, this flexible full cell can still exhibit a stable and safe electrochemical performance. This work may lead to a promising, low cost sodium full cell strategy for next-generation flexible energy storage devices.
