Co-reporter:Qinghua Liang 梁庆华;Zhi Li 李智;Yu Bai 白宇;Zheng-Hong Huang 黄正宏
Science China Materials 2017 Volume 60( Issue 2) pp:109-118
Publication Date(Web):2017 February
DOI:10.1007/s40843-016-5131-9
Two-dimensional graphitic carbon nitride (g-C3N4) nanosheets (GCNNs) have been considered as an attractive metal-free semiconductor because of their superior catalytic, optical, and electronic properties. However, it is still challenging to prepare monolayer GCNNs with a reduced lateral size in nanoscale. Herein, a highly efficient ultrasonic technique was used to prepare nanosized monolayer graphitic carbon nitride nanosheets (NMGCNs) with a thickness of around 0.6 nm and an average lateral size of about 55 nm. With a reduced lateral size yet monolayer thickness, NMGCNs show unique photo-responsive properties as compared to both large-sized GCNNs and GCN quantum dots. A dispersion of NMGCNs in water has good stability and exhibits strong blue fluorescence with a high quantum yield of 32%, showing good biocompatibility for cell imaging. Besides, compared to the multilayer GCNNs, NMGCNs show a highly improved photocatalysis under visible light irradiation. Overall, NMGCNs, characterized with monolayer and nanosized lateral dimension, fill the gap between large size (very high aspect ratio) and quantum dot-like counterparts, and show great potential applications as sensors, photo-related and electronic devices.不含金属的二维石墨相氮化碳纳米片由于具有优异的催化、光学及电学性能而受到研究者的广泛关注. 然而制备纳米级尺寸的单层石墨相氮化碳纳米片仍然存在挑战. 本文采用一种高效超声方法制备了横向尺寸约为55 nm, 厚度约为0.6 nm的单层石墨相氮化碳纳米片(NMGCNs). 由于其纳米级尺寸及单层片状结构, NMGCNs表现出与大尺寸纳米片和量子点显著不同的光响应特性. NMGCNs的水分散溶液具有良好的稳定性能和优异的荧光性能, 荧光量子产率可达32%, 所以可用于细胞荧光成像. 此外, NMGCNs表现出比多层石墨相氮化碳纳米片更优异的可见光催化性能. 独特的小尺寸及单层超薄结构使得NMGCNs在传感器和光电子等领域都具有潜在应用前景.
Co-reporter:Chen Zhang, Zhijia Huang, Wei Lv, Qinbai Yun, Feiyu Kang, Quan-Hong Yang
Carbon 2017 Volume 123(Volume 123) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.carbon.2017.08.027
The currently available commercial lithium-ion batteries (LIBs) with a relatively low energy density cannot meet the growing demands of energy storage systems for portable electronics and electric vehicles. Lithium metal with its high specific capacity (3860 mA h/g) is regarded as one of the most promising anode materials for next-generation rechargeable lithium batteries including Li-S and Li-air batteries. However, the safety issues induced by Li dendrites and the low Coulombic efficiency of this battery limit the cycle life and thus hinder its practical utilization. Carbon materials and their composites with controllable structures and properties, have been explored to address these issues and show great potential for lithium anode protection. In this review, various protection strategies of the Li metal anode using carbon materials are summarized and the rational design of carbon materials with different functions and their roles in Li metal protection are discussed in details. More importantly, the remaining problems and possible solutions for the future development of carbon materials for use with Li anodes are commented and prospected.Download high-res image (130KB)Download full-size image
Co-reporter:Qinbai Yun;Yan-Bing He;Wei Lv;Yan Zhao;Baohua Li;Feiyu Kang
Advanced Materials 2016 Volume 28( Issue 32) pp:6932-6939
Publication Date(Web):
DOI:10.1002/adma.201601409
Co-reporter:Shuzhang Niu, Guangmin Zhou, Wei Lv, Huifa Shi, Chong Luo, Yanbing He, Baohua Li, Quan-Hong Yang, Feiyu Kang
Carbon 2016 Volume 109() pp:1-6
Publication Date(Web):November 2016
DOI:10.1016/j.carbon.2016.07.062
Nitrogen-doped microporous carbon spheres (NPCSs) with a high surface area (1958 m2 g−1), large micropore volume and a high nitrogen content were synthesized by a simple one-step polymerization and subsequent ZnCl2 activation. The NPCSs can host a large number of small sulfur molecules, and restrict the reaction between the carbonate-based electrolytes and polysulfides. As a result, the NPCSs-sulfur (NPCSS) cathode exhibits excellent cyclic stability (initial capacity of 1382 mAh g−1 and 1002 mAh g−1 after 200 cycles at 0.3 C) and high rate performance (645 mAh g−1 at 3 C) even using the conventional carbonate-based electrolytes, demonstrating its potential use in long-life, safe lithium-sulfur batteries.
Co-reporter:Rui Tang, Qinbai Yun, Wei Lv, Yan-Bing He, Conghui You, Fangyuan Su, Lei Ke, Baohua Li, Feiyu Kang, Quan-Hong Yang
Carbon 2016 Volume 103() pp:356-362
Publication Date(Web):July 2016
DOI:10.1016/j.carbon.2016.03.032
This work demonstrates how a very low fraction of graphene greatly enhances the usage efficiency of carbon-based conductive additive in LiCoO2-based lithium ion batteries (LIB) and develops a strategy using binary conductive additive to have a high performance battery, especially with excellent rate performance. With a much lower fraction of carbon additive for a commercial LIB, only 0.2 wt% graphene nanosheet (GN) together with 1 wt% Super-P (SP) constructing an effective conductive network, the prepared battery exhibits outstanding cycling stability (146 mAhg−1 at 1C with retention of 96.4% after 50 cycles) and rate capability (116.5 mAhg−1 even at 5C). In this battery, a composite conducting network is formed with a long-range electron pathway formed by a trace amount of GN and the short-range electron pathway by aggregation of SP particles. More interestingly, in micro-sized LiCoO2 system, the GN additive does not present hindrance effect for lithium ion transport even in high rate discharge, which is entirely different from the nano-sized LiFePO4 system. This study further demonstrates commercial potential of GN additive for high performance LIB and more importantly gives a well-designed recipe for its real application.
Co-reporter:Zheng-Ze Pan, Hirotomo Nishihara, Shinichiroh Iwamura, Takafumi Sekiguchi, Akihiro Sato, Akira Isogai, Feiyu Kang, Takashi Kyotani, and Quan-Hong Yang
ACS Nano 2016 Volume 10(Issue 12) pp:
Publication Date(Web):November 3, 2016
DOI:10.1021/acsnano.6b05808
Honeycomb structures have been attracting attention from researchers mainly for their high strength-to-weight ratio. As one type of structure, honeycomb monoliths having microscopically dimensioned channels have recently gained many achievements since their emergence. Inspired by the microhoneycomb structure that occurs in natural tree xylems, we have been focusing on the assembly of such a structure by using the major component in tree xylem, cellulose, as the starting material. Through the path that finally led us to the successful reconstruction of tree xylems by the unidirectional freeze-drying (UDF) approach, we verified the function of cellulose nanofibers, toward forming xylem-like monoliths (XMs). The strong tendency of cellulose nanofibers to form XMs through the UDF approach was extensively confirmed with surface grafting or a combination of a variety of second components (or even a third component). The resulting composite XMs were thus imparted with extra properties, which extends the versatility of this kind of material. Particularly, we demonstrated in this paper that XMs containing reduced graphene oxide (denoted as XM/rGO) could be used as strain sensors, taking advantage of their penetrating microchannels and the bulk elasticity property. Our methodology is flexible in its processing and could be utilized to prepare various functional composite XMs.Keywords: cellulose nanofiber; microhoneycomb; strain sensor; TEMPO-mediated oxidation; unidirectional freeze-drying; xylem-like monolith;
Co-reporter:Qinghua Liang;Zhi Li;Xiaoliang Yu;Zheng-Hong Huang;Feiyu Kang
Advanced Materials 2015 Volume 27( Issue 31) pp:4634-4639
Publication Date(Web):
DOI:10.1002/adma.201502057
Co-reporter:Qinghua Liang;Zhi Li;Zheng-Hong Huang;Feiyu Kang
Advanced Functional Materials 2015 Volume 25( Issue 44) pp:6885-6892
Publication Date(Web):
DOI:10.1002/adfm.201503221
2D graphitic carbon nitride (GCN) nanosheets have attracted tremendous attention in photocatalysis due to their many intriguing properties. However, the photocatalytic performance of GCN nanosheets is still restricted by the limited active sites and the serious aggregation during the photocatalytic process. Herein, a simple approach to produce holey GCN (HGCN) nanosheets with abundant in-plane holes by thermally treating bulk GCN (BGCN) under an NH3 atmosphere is reported. These formed in-plane holes not only endow GCN nanosheets with more exposed active edges and cross-plane diffusion channels that greatly speed up mass and photogenerated charge transfer, but also provide numerous boundaries and thus decrease the aggregation. Compared to BGCN, the resultant HGCN has a much higher specific surface area of 196 m2 g−1, together with an enlarged bandgap of 2.95 eV. In addition, the HGCN is demonstrated to be self-modified with carbon vacancies that make HGCN show much broader light absorption extending to the near-infrared region, a higher donor density, and remarkably longer lifetime of charge carriers. As such, HGCN has a much higher photocatalytic hydrogen production rate of nearly 20 times the rate of BGCN.
Co-reporter:Shuzhang Niu, Wei Lv, Chen Zhang, Fangfei Li, Linkai Tang, Yanbing He, Baohua Li, Quan-Hong Yang and Feiyu Kang
Journal of Materials Chemistry A 2015 vol. 3(Issue 40) pp:20218-20224
Publication Date(Web):24 Aug 2015
DOI:10.1039/C5TA05324B
A sheet-like carbon sandwich, which contains a graphene layer as the conductive filling with N-doped porous carbon layers uniformly coated on both sides, is designed as a novel sulfur reservoir for lithium–sulfur batteries and experimentally obtained by a hydrothermal process of a mixture of graphene oxide, glucose and pyrrole, followed by KOH activation. In the hydrothermal process, graphene oxide is both employed as the precursor for the central graphene filling and a sheet-like template for both-side formation of N-doped porous carbon layers, resulting in an N-doped carbon sandwich structure (N-CS). This carbon sandwich is about 50–70 nm in thickness and has a high specific surface area (∼2677 m2 g−1) and a large pore volume (∼1.8 cm3 g−1), making it a promising high capacity reservoir for sulfur and polysulfide in a lithium–sulfur cell. The sheet-like morphology and the interconnected pore structure of the N-CS, together with a nitrogen content of 2.2%, are transformed to the assembled N-CS/sulfur cell with a high rate performance and excellent cycling stability because of fast ion diffusion and electron transfer. At a 2C rate, the reversible capacity is up to 625 mA h g−1 and remains at 461 mA h g−1 after 200 cycles with only 0.13% capacity fading per cycle. More interestingly, the sheet-like structure helps the N-CS materials form a tightly stacked coating on an electrode sheet, guaranteeing a volumetric capacity as high as 350 mA h cm−3.
Co-reporter:Xiaohui Lv, Wei Lv, Wei Wei, Xiaoyu Zheng, Chen Zhang, Linjie Zhi and Quan-Hong Yang
Chemical Communications 2015 vol. 51(Issue 18) pp:3911-3914
Publication Date(Web):30 Jan 2015
DOI:10.1039/C4CC09930C
A hybrid of holey graphene and Mn3O4 is prepared by a one-step process, in which the formation of a holey structure is accompanied with Mn3O4 nanoparticles through a high temperature reaction between graphene oxide sheets and KMnO4. Holey graphene and Mn3O4 collaboratively attributed to the enhanced catalytic activity and efficiency towards the oxygen reduction reaction.
Co-reporter:Shuzhang Niu, Wei Lv, Guangmin Zhou, Yanbing He, Baohua Li, Quan-Hong Yang and Feiyu Kang
Chemical Communications 2015 vol. 51(Issue 100) pp:17720-17723
Publication Date(Web):13 Oct 2015
DOI:10.1039/C5CC07226C
Nitrogen and sulfur co-doped porous carbon spheres (NS-PCSs) were prepared using L-cysteine to control the structure and functionalization during the hydrothermal reaction of glucose and the subsequent activation process. As the sulfur hosts in Li–S batteries, NS-PCSs combine strong physical confinement and surface chemical interaction to improve the affinity of polysulfides to the carbon matrix.
Co-reporter:Ling Ye, Qinghua Liang, Yu Lei, Xiaoliang Yu, Cuiping Han, Wanci Shen, Zheng-Hong Huang, Feiyu Kang, Quan-Hong Yang
Journal of Power Sources 2015 Volume 282() pp:174-178
Publication Date(Web):15 May 2015
DOI:10.1016/j.jpowsour.2015.02.028
•A LIC is constructed with LTO/C and PGM as the anode and cathode, respectively.•The optimized LIC delivers a maximum energy density of 72 Wh kg−1 at 650 W kg−1.•The LIC still reaches 40 Wh kg−1 at 8.3 kW kg−1.•The LIC retains 65% after 1000 cycles even at a high current density of 10 A g−1.A Li-ion capacitor (LIC) is constructed with Li4Ti5O12/C hybrid as the negative electrode and 3D porous graphene macroform (PGM) as the positive electrode. After optimizing the mass ratio (m+/m−) of the electrode materials with the value of 2, the as-fabricated LIC delivers a maximum energy density of 72 Wh kg−1 with the power density of 650 W kg−1 in a voltage range of 1.0–3.0 V. Furthermore, the energy density of the LIC reaches 40 Wh kg−1 even at a high power density of 8.3 kW kg−1. More significantly, the LIC exhibits a good cycling stability with the retention of 65% after 1000 cycles at a high current density of 10 A g−1, suggesting great potential application in energy storage of the LIC.A Li-ion capacitor constructed with a Li4Ti5O12/C hybrid based anode and a porous graphene macroform based cathode is demonstrated with both high energy and power densities.
Co-reporter:Qinbai Yun, Xianying Qin, Wei Lv, Yan-Bing He, Baohua Li, Feiyu Kang, Quan-Hong Yang
Carbon 2015 Volume 93() pp:59-67
Publication Date(Web):November 2015
DOI:10.1016/j.carbon.2015.05.032
Graphene and other carbon materials have been combined with various silicon (Si) nanostructures to accommodate the volume change of Si and enhance their electrical conductivity. However, for most of the formed hybrids, their low initial Coulombic efficiency (CE), fragile structures and poor stability cannot meet the practical application of battery. In this work, inspired by the structure and composition of reinforced concrete, a Si nanoparticles embedded in porous carbon/graphene (Si-C/G) electrode is fabricated through directly calcining a Si-polyacrylonitrile/graphene oxide precursor on a current collector. In this concrete-like structure, amorphous carbon, the carbonization product of polyacrylonitrile, acts as the “cement” and binds all components together. The flexible graphene network effectively enhances the strength, flexibility and conductivity of the electrode, as does the reinforcing rod framework in concrete. This carbon/graphene scaffold can accommodate the volume expansion of Si and isolate Si from electrolyte. Such Si-C/G electrode with small surface area and compact structure achieves a high initial CE of 78% and a reversible capacity of 1711 mAh g−1, as well as outstanding rate and cycling performances.
Co-reporter:Lei Ke, Wei Lv, Fang-Yuan Su, Yan-Bing He, Cong-Hui You, Baohua Li, Zhengjie Li, Quan-Hong Yang, Feiyu Kang
Carbon 2015 Volume 92() pp:311-317
Publication Date(Web):October 2015
DOI:10.1016/j.carbon.2015.04.064
Because of high electrical conductivity, graphene has been widely investigated as conductive additive in lithium-ion batteries. Whereas, it is found that graphene has quite different influences on the rate performance in diverse evaluation systems, such as commercial soft-packed cells and coin half-cells. It has been proved that the coin cells show better high-rate performance with the increase of graphene content, while it is of the opposite trend in commercial cells. In normal cases, the electrode thickness of coin cells is much smaller than that of commercial cells. Herein, it is found that the electrode thickness has a considerable effect on the high-rate performance of LiFePO4 electrode in which graphene is used as the conductive additive. Thicker electrode results in a longer Li-ion diffusion path, and thus the steric effect that graphene could hinder the Li-ion diffusion is amplified, inducing much higher polarization and poorer performance at high rate. Comparatively, this phenomenon is not obvious in thinner electrode. Thus, when more graphene is introduced in thick electrode, the power performance is greatly weakened as is observed in the commercial cells. This finding is of great importance for designing a high-performance commercial lithium-ion battery with graphene additives.
Co-reporter:Shuzhang Niu, Wei Lv, Chen Zhang, Yanting Shi, Jianfeng Zhao, Baohua Li, Quan-Hong Yang, Feiyu Kang
Journal of Power Sources 2015 Volume 295() pp:182-189
Publication Date(Web):1 November 2015
DOI:10.1016/j.jpowsour.2015.06.122
•The GCS hybrid was prepared by one-pot reduction-initiated self-assembly.•The hybrid showed a stable 3D network formed by graphene and carbon nanotubes.•The hybrid showed high specific capacity and stable capacity retention.A graphene/carbon nanotube (CNT)/sulfur (denoted GCS) hybrid with interconnected structure is prepared through a one-pot self-assembly approach initiated by l-ascorbic acid reduction under a mild condition. In such a solution-based assembly process, the formation of an interconnected graphene/CNT conductive network is accompanied by the uniform loading of sulfur, whose fraction is as high as of 70 wt%. The as-prepared GCS hybrid delivers an initial capacity of 1008 mAh g−1 at 0.3C and maintains 704 mAh g−1 after 100 cycles. Remarkably, at a high rate of 1.0C, the cathode shows an excellent cyclic performance with a capacity of 657 mAh g−1 after 450 ycles and the capacity decay is only 0.04% per cycle. Moreover, the superior rate performance of GCS hybrid is attributed to the conductive network formed by interconnected graphene sheets and CNT, which supply an unimpeded and continuous path for electron and Li ion transfer and accommodate the volume variation of sulfur during charge/discharge cycling. In addition, the residual functional groups on GCS can retain intimate contact of the conducting matrix with sulfur and effectively confine the diffusion of polysulfides. This study gives an eco-friendly and highly effective solution-based approach for carbon–sulfur electrode for lithium–sulfur battery.
Co-reporter:Wei Lv; Chen Zhang; Zhengjie Li
The Journal of Physical Chemistry Letters 2015 Volume 6(Issue 4) pp:658-668
Publication Date(Web):January 28, 2015
DOI:10.1021/jz502655m
Three-dimensional (3D) graphene-assembled monoliths (GAs), especially ones prepared by self-assembly in the liquid phase, represent promising forms to realize the practical applications of graphene due to their high surface utilization and operability. However, the understanding of the assembly process and structure control of 3D GAs, as a new class of carbon materials, is quite inadequate. In this Perspective, we give a demonstration of the assembly process and discuss the key factors involved in the structure control of 3D GAs to pave the way for their future applications. It is shown that the assembly process starts with the phase separation, which is responsible for the formation of the 3D networked structure and liquid phase as the spacers avoid the parallel overlap of graphene layers and help form an interlinked pore system. Well-tailored graphene sheets and selected assembly media must be a precondition for a well-controlled assembly process and microstructure of a 3D GA. The potential applications in energy storage featuring high rate and high volumetric energy density demonstrate advantages of 3D GAs in real applications.
Co-reporter:Qinghua Liang, Ling Ye, Zheng-Hong Huang, Qiang Xu, Yu Bai, Feiyu Kang and Quan-Hong Yang
Nanoscale 2014 vol. 6(Issue 22) pp:13831-13837
Publication Date(Web):16 Sep 2014
DOI:10.1039/C4NR04541F
A cost-effective approach to obtain electrode materials with excellent electrochemical performance is critical to the development of supercapacitors (SCs). Here we report the preparation of a three-dimensional (3D) honeycomb-like porous carbon (HLPC) by the simple carbonization of pomelo peel followed by KOH activation. Structural characterization indicates that the as-prepared HLPC with a high specific surface area (SSA) up to 2725 m2 g−1 is made up of interconnected microporous carbon walls. Chemical analysis shows that the HLPC is doped with nitrogen and also has oxygen-containing groups. Electrochemical measurements show that the HLPC not only exhibits a high specific capacitance of 342 F g−1 and 171 F cm−3 at 0.2 A g−1 but also shows considerable rate capability with a retention of 62% at 20 A g−1 as well as good cycling performance with 98% retention over 1000 cycles at 10 A g−1 in 6 M KOH. Furthermore, an as-fabricated HLPC-based symmetric SC device delivers a maximum energy density of ∼9.4 Wh kg−1 in the KOH electrolyte. Moreover, the outstanding cycling stability (only 2% capacitance decay over 1000 cycles at 5 A g−1) of the SC device makes it promising for use in a high-performance electrochemical energy system.
Co-reporter:Juanjuan Liu, Wei Lv, Wei Wei, Chen Zhang, Zhengjie Li, Baohua Li, Feiyu Kang and Quan-Hong Yang
Journal of Materials Chemistry A 2014 vol. 2(Issue 9) pp:3031-3037
Publication Date(Web):12 Dec 2013
DOI:10.1039/C3TA14315E
This study presents a method to optimize the mass transport and electron transfer of metal oxides in electrochemical processes by using a three-dimensional (3D) porous graphene macroassembly (GM) as a framework. A simple method, pressurized infiltration, is reported to realize uniform dispersion of metal oxide nanoparticles on the graphene skeleton in the GM. The obtained GM–NiO hybrid shows significantly improved performance in electrochemical catalytic processes and energy storage applications. When used as the active material in nonenzymic sensors, it shows a low detection limit towards glucose while maintaining high sensitivity. It also shows a high capacitance of about 727 F g−1 and maintains high rate performance when used as the electrode material for supercapacitors. More importantly, this method may be sufficiently versatile for the hybridization of different kinds of noncarbon materials with GM to promote their practical applications.
Co-reporter:Zhengjie Li, Wei Lv, Chen Zhang, Jiwen Qin, Wei Wei, Jiao-Jing Shao, Da-Wei Wang, Baohua Li, Feiyu Kang and Quan-Hong Yang
Nanoscale 2014 vol. 6(Issue 16) pp:9554-9558
Publication Date(Web):16 Jun 2014
DOI:10.1039/C4NR01924E
Flattened Sn sheets are prepared from the pre-seeded Sn salt in the interlayer nanospace of a graphene membrane, which acts as a template to shape Sn crystals and prevent the aggregation. The sandwich structure clamping Sn sheets accommodates the volume change during charge/discharge. We show that the hybrid possesses excellent rate performance and cycling stability as an anode for lithium ion batteries.
Co-reporter:Jiao-Jing Shao, Zheng-Jie Li, Chen Zhang, Li-Fang Zhang and Quan-Hong Yang
Journal of Materials Chemistry A 2014 vol. 2(Issue 6) pp:1940-1946
Publication Date(Web):26 Nov 2013
DOI:10.1039/C3TA14134A
Two distinct graphene sheets, highly flat graphene and wavy graphene, were used as support materials for in situ nucleation and growth of platinum nanoparticles (Pt NPs) to synthesize graphene/Pt catalysts. The average size of Pt NPs on the wavy graphene sheets is around 2 nm and is smaller than those on the flat graphene sheets. The electrochemical activity of the two as-prepared catalysts towards methanol oxidation was investigated and compared with that of a commercial Pt/carbon black (Pt/C) catalyst, and electrochemical results showed that the wavy graphene/Pt catalyst possessed the best poison tolerance and comparable electrochemical surface area to the commercial Pt/C catalyst. The wavy microstructure is believed to be responsible for the stable dispensability of the as-prepared wavy graphene and the acquisition of small size Pt NPs, since the abundant ripples coming from the wavy microstructure effectively prevent the aggregation of the graphene sheets, and also act as barriers to prevent agglomeration of Pt NPs during their in situ nucleation and growth process. This work indicates that the microstructure of the supporting material plays a crucial role in the electrochemical performance of platinum-based catalysts.
Co-reporter:Jiwen Qin, Wei Lv, Zhengjie Li, Baohua Li, Feiyu Kang and Quan-Hong Yang
Chemical Communications 2014 vol. 50(Issue 88) pp:13447-13450
Publication Date(Web):27 Aug 2014
DOI:10.1039/C4CC05065G
A silver vanadium oxide (SVO) material with an interlaced structure was prepared using graphene as a two-dimensional substrate that directs the crystal growth in the hydrothermal process. The obtained SVO–graphene hybrid showed high structural stability, and lithium ion batteries (LIBs) using the hybrid as the cathode showed excellent cycling stability and rate performance.
Co-reporter:Hai-Yong Dong, Yan-Bing He, Baohua Li, Chen Zhang, Ming Liu, Fangyuan Su, Wei Lv, Feiyu Kang, Quan-Hong Yang
Electrochimica Acta 2014 Volume 142() pp:247-253
Publication Date(Web):1 October 2014
DOI:10.1016/j.electacta.2014.07.045
A novel Li4Ti5O12 (LTO) electrode with a hierarchical carbon-based conducting network has been developed for high rate lithium ion battery. The unique network is constructed by graphene sheets (GS) that are not only dispersed among (inter-) but also inside (intra-) LTO particles, together with a thin carbon layer wrapping around the LTO particles. The intraparticle GS promotes the electron transfer inside LTO particles while the interparticle GS together with carbon coating bridges the particles guaranteeing fast electron transfer among LTO particles, which construct a highway throughout the whole electrode sheet. Quantitatively, only a trace amount of GS (∼ 0.4 wt%) synergistic with carbon coating (∼0.8 wt%) contributes to a more effective conducting network in the produced LTO electrode and as a result much better performance as compared to the LTO case with similar carbon coating but free of GS. Due to the effectiveness of the conducting network, even with a tap density as high as ∼1.0 g cm−3, the novel LTO possesses both excellent rate performance and cycling behaviors. The capacity of 123.5 mA h g−1 is obtained at a charge/discharge rate as high as 30 C and a very high capacity of 144.8 mAh g−1 is maintained even after 100 cycles at 10 C. Due to such a low fraction of carbon and a high tape density, the novel LTO electrode has a great practical application value in both the power and energy storage lithium ion batteries.
Co-reporter:Cuiping Han; Yan-Bing He; Baohua Li;Hongfei Li;Dr. Jun Ma; Hongda Du;Dr. Xianying Qin; Quan-Hong Yang; Feiyu Kang
ChemSusChem 2014 Volume 7( Issue 9) pp:2567-2574
Publication Date(Web):
DOI:10.1002/cssc.201402305
Abstract
Sheets of Li4Ti5O12 with high crystallinity are coated with nitrogen-doped carbon (NC-LTO) using a controlled process, comprising hydrothermal reaction followed by chemical vapor deposition (CVD). Acetonitrile (CH3CN) vapor is used as carbon and nitrogen source to obtain a thin coating layer of nitrogen-doped carbon. The layer enables the NC-LTO material to maintain its sheet structure during the high-temperature CVD process and to achieve high crystallinity. Doping with nitrogen introduces defects into the carbon coating layer, and this increased degree of disorder allows fast transportation of lithium ions in the layer. An electrode of NC-LTO synthesized at 700 °C exhibits greatly improved rate and cycling performance due to a markedly decreased total cell resistance and enhanced Li-ion diffusion coefficient (DLi). Specific capacities of 159.2 and 145.8 mA h g−1 are obtained using the NC-LTO sheets, at charge/discharge rates of 1 and 10 C, respectively. These values are much higher than values for LTO particles did not undergo the acetonitrile CVD treatment. A capacity retention value as high as 94.7 % is achieved for the NC-LTO sheets after 400 cycles in a half-cell at 5 C discharge rate.
Co-reporter:Tingting Xie, Wei Lv, Wei Wei, Zhengjie Li, Baohua Li, Feiyu Kang and Quan-Hong Yang
Chemical Communications 2013 vol. 49(Issue 88) pp:10427-10429
Publication Date(Web):18 Sep 2013
DOI:10.1039/C3CC46455E
A unique carbon with a high specific surface area was prepared by carbonization of a polymer-based precursor, agar, in the presence of graphene. Graphene prevents the shrinkage and aggregation of the carbonized particles, resulting in extraordinarily large external surface area (∼1200 m2 g−1) of the carbon, which shows a high rate performance as a supercapacitor electrode.
Co-reporter:Xiaoying Xie, Chen Zhang, Ming-Bo Wu, Ying Tao, Wei Lv and Quan-Hong Yang
Chemical Communications 2013 vol. 49(Issue 94) pp:11092-11094
Publication Date(Web):08 Oct 2013
DOI:10.1039/C3CC46867D
Graphene oxide hydrogel is used as a reactive template to prepare nanoporous materials with a 3D microstructure. The as-prepared porous MnO2 shows a capacitance retention of ∼70.6% at a current density as high as 15 A g−1, resulting from the 3D interconnected ion transport channel replicated from the graphene oxide hydrogel.
Co-reporter:Chen Zhang, Wei Lv, Xiaoying Xie, Daiming Tang, Chang Liu, Quan-Hong Yang
Carbon 2013 Volume 62() pp:11-24
Publication Date(Web):October 2013
DOI:10.1016/j.carbon.2013.05.033
Realizing mass production of graphene materials at low cost and high quality is urgently required for their real applications. Thermal exfoliation of graphite oxide (GO) is considered as a promising strategy though it normally requires a high exfoliation temperature together with a fast heating rate, making the produced graphenes suffer from high cost and concentrated topological defects. A mild exfoliation of GO at a far lower temperature than the predicted minimum temperature, has been demonstrated by introducing a high vacuum to exert an outward drawing force which helps effective exfoliation of the stacked graphene layers. In this contribution, together with a discussion on the foundation of thermal exfoliation and the general principle for low-temperature exfoliation, we review current strategies and indicate possible novel approaches. Low cost and easy operability are highlighted for the low-temperature exfoliation and the resulting graphene materials are characterized by low defect concentration, and unique and tunable surface chemistry to promote potential mass applications in energy-related areas.
Co-reporter:Si-Da Wu, Wei Lv, Jia Xu, Dan Han, Xu Chen, Pu Wang and Quan-Hong Yang
Journal of Materials Chemistry A 2012 vol. 22(Issue 33) pp:17204-17209
Publication Date(Web):03 Jul 2012
DOI:10.1039/C2JM32326E
A liquid–air self-assembly strategy is proposed to uniformly hybridize hydrophobic graphene with amphiphilic polymer, like PVA (poly(vinyl alcohol)), in a thin membrane, where the polymer imparts aqueous-dispersion and membrane-forming abilities to the encapsulated graphene. The microstructure, transmittance and wettability of the GNS/PVA hybrid membranes are finely tunable by changing the GNS fraction. Due to strong interaction between GNSs and PVA, the GNS-incorporated hybrid membrane formed at liquid–air interface shows improved thermal stability and highly enhanced mechanical performance as compared to GNS-free PVA membrane. Also, well-distributed GNS in the transparent polymer carrier make the hybrid membrane an ideal saturable absorber in ultrafast laser systems.
Co-reporter:Jiao-Jing Shao, Wei Lv, Quangui Guo, Chen Zhang, Qiang Xu, Quan-Hong Yang and Feiyu Kang
Chemical Communications 2012 vol. 48(Issue 31) pp:3706-3708
Publication Date(Web):21 Nov 2011
DOI:10.1039/C1CC16838J
The liquid/air interface provides an ideal platform for the uniform hybridization of multi-components in a thin graphene-based membrane through self-assembly. This study presents the first example for such a hybrid membrane which combines chemically active GO layers with highly conductive carbon nanotubes.
Co-reporter:Cheng Zheng, Shuzhang Niu, Wei Lv, Guangmin Zhou, Jia Li, Shaoxun Fan, Yaqian Deng, Zhengze Pan, Baohua Li, Feiyu Kang, Quan-Hong Yang
Nano Energy (March 2017) Volume 33() pp:
Publication Date(Web):March 2017
DOI:10.1016/j.nanoen.2017.01.040
•A 3D porous graphene with α-Fe2O3 nanoparticles (NPs) is designed as a sulfur host.•α-Fe2O3 NPs are proved to chemically promote lithium polysulfides transformation.•The 3D hierarchical porous structure facilitates fast electron/ion transfer.•This sulfur host contributes to a high rate performance and long cyclic stability.A three-dimensional (3D) hierarchical porous graphene macrostructure coupled with uniformly distributed α-Fe2O3 nano-particles (denoted Fe-PGM) was designed as a sulfur host in a lithium-sulfur battery, and was prepared by a hydrothermal method. In this hybrid structure, the α-Fe2O3 nano-particles are proved to not only strongly interact with the polysulfides, but more importantly, chemically promote their transformation to insoluble species during the charge/discharge process, working as chemical barriers for the shuttling of the lithium polysulfides (LiPSs). Therefore, together with 3D hierarchical porous structure facilitating fast electron/ion transfer, Fe-PGM as a sulfur host in a cathode contributes to a high rate performance (565 mAh g−1 at a high rate of 5 C relative to 1571 mAh g−1 at 0.3 C) as well as long cyclic stability (an ultralow capacity fading rate of 0.049% per cycle over 1000 cycles at the high current rate of 5 C).A three-dimensional (3D) hierarchical porous graphene macrostructure coupled with uniformly distributed α-Fe2O3 nano-particles (denoted Fe-PGM) was designed as a sulfur host in a Lithium-sulfur battery and prepared by a one-pot hydrothermal strategy. The Fe2O3 NPs not only restrain the shuttling of LiPS by chemical adsorption as other oxides do, but also accelerate the transformation of the soluble LiPSs to insoluble products, which has never been reported. Therefore, together with 3D hierarchical porous structure facilitating fast electron/ion transfer, Fe-PGM as a sulfur host in a cathode contributes to a high rate performance as well as long cyclic stability.
Co-reporter:Wei Lv, Zhengjie Li, Yaqian Deng, Quan-Hong Yang, Feiyu Kang
Energy Storage Materials (January 2016) Volume 2() pp:107-138
Publication Date(Web):1 January 2016
DOI:10.1016/j.ensm.2015.10.002
The demand for high performance electrochemical energy storage devices has significantly increased in recent years and many efforts have been made to develop advanced electrode materials. In this respect, graphene-based materials, considered promising high performance electrode materials, have drawn great attention because they can increase the performance of the currently-used devices, such as the Lithium-ion battery and supercapacitor, and make next generation devices, such as the Lithium–sulfur battery, Lithium–O2 battery and Sodium-ion battery, more practical. This review summarizes the current uses of graphene-based materials in these devices and demonstrates their advances. It also discusses the opportunities for graphene in high performance electrode material preparation and device configuration, and more importantly, the challenges of graphene for practical use in these devices. Finally, perspectives and possible breakthroughs for future graphene-based materials are also briefly discussed.
Co-reporter:Si-Da Wu, Wei Lv, Jia Xu, Dan Han, Xu Chen, Pu Wang and Quan-Hong Yang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 33) pp:
Publication Date(Web):
DOI:10.1039/C2JM32326E
Co-reporter:Shuzhang Niu, Wei Lv, Guangmin Zhou, Yanbing He, Baohua Li, Quan-Hong Yang and Feiyu Kang
Chemical Communications 2015 - vol. 51(Issue 100) pp:NaN17723-17723
Publication Date(Web):2015/10/13
DOI:10.1039/C5CC07226C
Nitrogen and sulfur co-doped porous carbon spheres (NS-PCSs) were prepared using L-cysteine to control the structure and functionalization during the hydrothermal reaction of glucose and the subsequent activation process. As the sulfur hosts in Li–S batteries, NS-PCSs combine strong physical confinement and surface chemical interaction to improve the affinity of polysulfides to the carbon matrix.
Co-reporter:Jiao-Jing Shao, Wei Lv, Quangui Guo, Chen Zhang, Qiang Xu, Quan-Hong Yang and Feiyu Kang
Chemical Communications 2012 - vol. 48(Issue 31) pp:NaN3708-3708
Publication Date(Web):2011/11/21
DOI:10.1039/C1CC16838J
The liquid/air interface provides an ideal platform for the uniform hybridization of multi-components in a thin graphene-based membrane through self-assembly. This study presents the first example for such a hybrid membrane which combines chemically active GO layers with highly conductive carbon nanotubes.
Co-reporter:Shuzhang Niu, Wei Lv, Chen Zhang, Fangfei Li, Linkai Tang, Yanbing He, Baohua Li, Quan-Hong Yang and Feiyu Kang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 40) pp:NaN20224-20224
Publication Date(Web):2015/08/24
DOI:10.1039/C5TA05324B
A sheet-like carbon sandwich, which contains a graphene layer as the conductive filling with N-doped porous carbon layers uniformly coated on both sides, is designed as a novel sulfur reservoir for lithium–sulfur batteries and experimentally obtained by a hydrothermal process of a mixture of graphene oxide, glucose and pyrrole, followed by KOH activation. In the hydrothermal process, graphene oxide is both employed as the precursor for the central graphene filling and a sheet-like template for both-side formation of N-doped porous carbon layers, resulting in an N-doped carbon sandwich structure (N-CS). This carbon sandwich is about 50–70 nm in thickness and has a high specific surface area (∼2677 m2 g−1) and a large pore volume (∼1.8 cm3 g−1), making it a promising high capacity reservoir for sulfur and polysulfide in a lithium–sulfur cell. The sheet-like morphology and the interconnected pore structure of the N-CS, together with a nitrogen content of 2.2%, are transformed to the assembled N-CS/sulfur cell with a high rate performance and excellent cycling stability because of fast ion diffusion and electron transfer. At a 2C rate, the reversible capacity is up to 625 mA h g−1 and remains at 461 mA h g−1 after 200 cycles with only 0.13% capacity fading per cycle. More interestingly, the sheet-like structure helps the N-CS materials form a tightly stacked coating on an electrode sheet, guaranteeing a volumetric capacity as high as 350 mA h cm−3.
Co-reporter:Xiaohui Lv, Wei Lv, Wei Wei, Xiaoyu Zheng, Chen Zhang, Linjie Zhi and Quan-Hong Yang
Chemical Communications 2015 - vol. 51(Issue 18) pp:NaN3914-3914
Publication Date(Web):2015/01/30
DOI:10.1039/C4CC09930C
A hybrid of holey graphene and Mn3O4 is prepared by a one-step process, in which the formation of a holey structure is accompanied with Mn3O4 nanoparticles through a high temperature reaction between graphene oxide sheets and KMnO4. Holey graphene and Mn3O4 collaboratively attributed to the enhanced catalytic activity and efficiency towards the oxygen reduction reaction.
Co-reporter:Jiao-Jing Shao, Zheng-Jie Li, Chen Zhang, Li-Fang Zhang and Quan-Hong Yang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 6) pp:NaN1946-1946
Publication Date(Web):2013/11/26
DOI:10.1039/C3TA14134A
Two distinct graphene sheets, highly flat graphene and wavy graphene, were used as support materials for in situ nucleation and growth of platinum nanoparticles (Pt NPs) to synthesize graphene/Pt catalysts. The average size of Pt NPs on the wavy graphene sheets is around 2 nm and is smaller than those on the flat graphene sheets. The electrochemical activity of the two as-prepared catalysts towards methanol oxidation was investigated and compared with that of a commercial Pt/carbon black (Pt/C) catalyst, and electrochemical results showed that the wavy graphene/Pt catalyst possessed the best poison tolerance and comparable electrochemical surface area to the commercial Pt/C catalyst. The wavy microstructure is believed to be responsible for the stable dispensability of the as-prepared wavy graphene and the acquisition of small size Pt NPs, since the abundant ripples coming from the wavy microstructure effectively prevent the aggregation of the graphene sheets, and also act as barriers to prevent agglomeration of Pt NPs during their in situ nucleation and growth process. This work indicates that the microstructure of the supporting material plays a crucial role in the electrochemical performance of platinum-based catalysts.
Co-reporter:Xiaoying Xie, Chen Zhang, Ming-Bo Wu, Ying Tao, Wei Lv and Quan-Hong Yang
Chemical Communications 2013 - vol. 49(Issue 94) pp:NaN11094-11094
Publication Date(Web):2013/10/08
DOI:10.1039/C3CC46867D
Graphene oxide hydrogel is used as a reactive template to prepare nanoporous materials with a 3D microstructure. The as-prepared porous MnO2 shows a capacitance retention of ∼70.6% at a current density as high as 15 A g−1, resulting from the 3D interconnected ion transport channel replicated from the graphene oxide hydrogel.
Co-reporter:Tingting Xie, Wei Lv, Wei Wei, Zhengjie Li, Baohua Li, Feiyu Kang and Quan-Hong Yang
Chemical Communications 2013 - vol. 49(Issue 88) pp:NaN10429-10429
Publication Date(Web):2013/09/18
DOI:10.1039/C3CC46455E
A unique carbon with a high specific surface area was prepared by carbonization of a polymer-based precursor, agar, in the presence of graphene. Graphene prevents the shrinkage and aggregation of the carbonized particles, resulting in extraordinarily large external surface area (∼1200 m2 g−1) of the carbon, which shows a high rate performance as a supercapacitor electrode.
Co-reporter:Jiwen Qin, Wei Lv, Zhengjie Li, Baohua Li, Feiyu Kang and Quan-Hong Yang
Chemical Communications 2014 - vol. 50(Issue 88) pp:NaN13450-13450
Publication Date(Web):2014/08/27
DOI:10.1039/C4CC05065G
A silver vanadium oxide (SVO) material with an interlaced structure was prepared using graphene as a two-dimensional substrate that directs the crystal growth in the hydrothermal process. The obtained SVO–graphene hybrid showed high structural stability, and lithium ion batteries (LIBs) using the hybrid as the cathode showed excellent cycling stability and rate performance.
Co-reporter:Juanjuan Liu, Wei Lv, Wei Wei, Chen Zhang, Zhengjie Li, Baohua Li, Feiyu Kang and Quan-Hong Yang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 9) pp:NaN3037-3037
Publication Date(Web):2013/12/12
DOI:10.1039/C3TA14315E
This study presents a method to optimize the mass transport and electron transfer of metal oxides in electrochemical processes by using a three-dimensional (3D) porous graphene macroassembly (GM) as a framework. A simple method, pressurized infiltration, is reported to realize uniform dispersion of metal oxide nanoparticles on the graphene skeleton in the GM. The obtained GM–NiO hybrid shows significantly improved performance in electrochemical catalytic processes and energy storage applications. When used as the active material in nonenzymic sensors, it shows a low detection limit towards glucose while maintaining high sensitivity. It also shows a high capacitance of about 727 F g−1 and maintains high rate performance when used as the electrode material for supercapacitors. More importantly, this method may be sufficiently versatile for the hybridization of different kinds of noncarbon materials with GM to promote their practical applications.
