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2014, Vol. 23, No. 3　Online: 2014-05-24


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Gao and coworkers in their Article on pages 274–281 reported the hydrothermal synthesis of spindle-like Li₂FeSiO₄ and Li₂FeSiO₄-C, as well as the application in the cathode fabrication for lithium-ion batteries. After carbon coating, the discharge capacity was greatly increased due to the enhanced electronic conductivity. In particular, Li₂FeSiO₄-C with carbon content of 7.21 wt% showed a discharge capacity of 160.9 mAh·g⁻¹ at room temperature and of 213 mAh·g⁻¹ at 45 ℃ (0.1 C), respectively.

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Preface

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Preface to Special Issue on Electrochemical Energy Storage and Conversion Jun Chen 2014, 23(3): 0-0.  摘要 ( 5260 )   PDF(75KB) ( 5 )          Energy utilization includes two aspects of storage and conversion. Both the density of energy storage and the efficiency of energy conversion are particularly considered in the application of energy. It is well known that chemical energy can be easily stored in chemical substances with high-energy density such as those containing hydrogen and lithium. Meanwhile, chemical energy can be highly converted into clean and efficient electrical energy through the systems of electrochemical energy storage and conversion, which include batteries, fuel cells, and electrochemical capacitors (also called supercapacitors). Thus, the combination of chemical energy and electrochemical reactions makes full use of the advantages of chemical energy and electrical energy. Nowadays, systems of electrochemical energy storage and conversion have already played an important role in powering an increasingly diverse range of applications from electronic devices to cars.        Systems of electrochemical energy storage and conversion depend on the composition and structure of the materials as well as the electrochemical processes involved. However, the existing systems have many problems which are not satisfactory for their ever-increasing applications, such as low reaction activity, limited mass transport and charge transfer, slow kinetics, and uncontrolled surface/interface, as well as the other scientific and technological problems in traditional energymaterials, and cause the low actual energy density and low energy conversion efficiency in current batteries, fuel cells and supercapacitors. No matter how to change the energy structure around the world in future, high-density storage and high-efficiency conversion of chemical energy and electrical energy are two crucial approaches in energy distribution and ultilization. Therefore, the exploration of new key materials for hydrogen or lithium-based systems with electrochemical energy storage and conversion is of importance.        This special issue collects 21 papers contributed by experts who are very lively in the frontier of academic field of electrochemical energy storage and conversion. It is really an interesting and exciting special issue that addresses on the topics of electrochemical hydrogen or lithium storage, cathode and anode materials for lithium-ion batteries, lithium-sulfur batteries, electrode materials for supercapacitors, electrocatalysis toward oxygen reduction reaction or ethanol oxidation, and electrolyte additives.        This special issue is dedicated to the research and development of systems with electrochemical energy storage and conversion. It reflects, in a certain degree, the latest research development, progress, problems and future focus on the direction of electrochemical energy storage and conversion. I believe that this special issue should play valuable roles in strengthening the exchanges of scientific workers, and promoting the research development of electrochemical energy storage and conversion.

COMMUNICATIONS

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Intermetallic Pt2Si：magnetron-sputtering preparation and electrocatalysis toward ethanol oxidation Zhandong Ren, Li Xiao, Gongwei Wang, Juntao Lu, Lin Zhuang 2014, 23(3): 265-268.  DOI: 10.1016/S2095-4956(14)60145-5 摘要 ( 7243 )   Although most transition metals have been tested as the promoter to Pt for electrocatalysis toward fuel cell reactions, semi-conductor elements, such as Si, have hitherto not been examined. Here we report a simple synthesis of intermetallic Pt2Si electrode using magnetron sputtering and the electrocatalysis toward ethanol oxidation reaction (EOR). In comparison to Pt, the intermetallic Pt2Si surface turns out to be much more active in catalyzing the EOR: the onset potential shifts negatively by 150 mV, and the current density at 0.6 V increases by a magnitude of one order. Such an enormous enhancement in EOR catalysis is ascribed to the promotion effects of Si, which can not only provide active surface oxygenated species to accelerate the removal of COads, but also strongly alter the electronic property of Pt, as clearly indicated by the core-level shift in XPS spectrum.

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Nano-sized carboxylates as anode materials for rechargeable lithium-ion batteries Xiaoyan Wu, Jie Ma, Yong-Sheng Hu, Hong Li, Liquan Chen 2014, 23(3): 269-273.  DOI: 10.1016/S2095-4956(14)60146-7 摘要 ( 7546 )   Nano-sized carboxylates Na2C7H3NO4 and Na2C6H2N2O4 were prepared and investigated as anode materials for lithium-ion batteries. Both carboxylates exhibit high reversible capacities around 190 mAh/g above a cut-off voltage of 0.8 V vs. Li+/Li, potentially improving the safety of the batteries. In addition, good rate performance and long cycle life of these carboxylates make them promising candidates as anode materials for lithium-ion batteries.

ARTICLES

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Hydrothermal synthesis of spindle-like Li2FeSiO4-C composite as cathode materials for lithium-ion batteries Haiyan Gao, Zhe Hu, Kai Zhang, Fangyi Cheng, Zhanliang Tao, Jun Chen 2014, 23(3): 274-281.  DOI: 10.1016/S2095-4956(14)60147-9 摘要 ( 6581 )   In this paper, we report on the preparation of Li2FeSiO4, sintered Li2FeSiO4, and Li2FeSiO4-C composite with spindle-like morphologies and their application as cathode materials of lithium-ion batteries. Spindle-like Li2FeSiO4 was synthesized by a facile hydrothermal method with (NH4)2Fe(SO4)2 as the iron source. The spindle-like Li2FeSiO4 was sintered at 600 ℃ for 6 h in Ar atmosphere. Li2FeSiO4-C composite was obtained by the hydrothermal treatment of spindle-like Li2FeSiO4 in glucose solution at 190 ℃ for 3 h. Electrochemical measurements show that after carbon coating, the electrode performances such as discharge capacity and high-rate capability are greatly enhanced. In particular, Li2FeSiO4-C with carbon content of 7.21 wt% delivers the discharge capacities of 160.9 mAh·g-1 at room temperature and 213 mAh·g-1 at 45 ℃(0.1 C), revealing the potential application in lithium-ion batteries.

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Molecular dynamics simulations of La2O3 thin films on SiO2 Mou Fang, Stephen P. Kelty, Xiangming He 2014, 23(3): 282-286.  DOI: 10.1016/S2095-4956(14)60148-0 摘要 ( 5808 )   Classical molecular dynamics is used to investigate the equilibrium state of the surface region and interface of heteroepitaxial La2O3 thin films. Due to the lattice mismatch, heteroepitaxial thin films are subject to very large stress. For this reason the behavior of La2O3 thin films at SiO2 interface becomes an important concern. Our result indicates that La2O3 can uniformly wet SiO2 surface. The properties of the simulated films are analyzed and the lack of any discernible crystalline phase in epitaxial La2O3 on SiO2 indicates that the lattice mismatch between SiO2 and La2O3 is sufficiently large to prevent the formation of even short-range orders in La2O3 film.

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Improved electrochemical hydrogen storage properties of Mg-Y thin films as a function of substrate temperature Yanyan Wang, Gongbiao Xin, Chongyun Wang, Huiyu Li, Wei Li, Jie Zheng, Xingguo Li 2014, 23(3): 287-290.  DOI: 10.1016/S2095-4956(14)60149-2 摘要 ( 6785 )   Pd-capped Mg78Y22 thin films have been prepared by direct current magnetron co-sputtering system at different substrate temperatures and their electrochemical hydrogen storage properties have been investigated. It is found that rising substrate temperature to 60 ℃ can coarsen the surface of thin film, thus facilitating the diffusion of hydrogen atoms and then enhancing its discharge capacity to ～1725 mAh·g-1. Simultaneously, the cyclic stability is effectively improved due to the increased adhesion force between film and substrate as a function of temperature. In addition, the specimen exhibits a very long and flat discharge plateau at about -0.67 V, at which nearly 60% of capacity is maintained. The property is favorable for the application in metal hydride/nickel secondary batteries. The results indicate that rising optimal substrate temperature has a beneficial effect on the electrochemical hydrogen storage of Mg-Y thin films.

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High-performance self-organized Si nanocomposite anode for lithium-ion batteries Xiuyun Zhao, Dingguo Xia, Lin Gu, Juncheng Yue, Biao Li, Hang Wei, Huijun Yan, Ruqiang Zou, Yingxia Wang, Xiayan Wang, Ze Zhang, Jixue Li 2014, 23(3): 291-300.  DOI: 10.1016/S2095-4956(14)60150-9 摘要 ( 7180 )   Silicon is being investigated extensively as an anodic material for next-generation lithium ion batteries for portable energy storage and electric vehicles. However, the large changes in volume during cycling lead to the breakdown of the conductive network in Si anodes and the formation of an unstable solid-electrolyte interface, resulting in capacity fading. Here, we demonstrate nanoparticles with a Si@Mn22.6Si5.4C4@C double-shell structure and the formation of self-organized Si-Mn-C nanocomposite anodes during the lithiation/delithiation process. The anode consists of amorphous Si particles less than 10 nm in diameter and separated by an interconnected conductive/buffer network, which exhibits excellent charge transfer kinetics and charge/discharge performances. A stable specific capacity of 1100 mAh·g-1 at 100 mA·g-1 and a coulombic efficiency of 99.2% after 30 cycles are achieved. Additionally, a rate capacity of 343 mAh·g-1 and a coulombic efficiency of 99.4% at 12000 mA·g-1 are also attainable. Owing to its simplicity and applicability, this strategy for improving electrode performance paves a way for the development of high-performance Si-based anodic materials for lithium ion batteries.

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Electrospun CuFe2O4 nanotubes as anodes for high-performance lithium-ion batteries Shengjie Peng, Linlin Li, Madhavi Srinivasan 2014, 23(3): 301-307.  DOI: 10.1016/S2095-4956(14)60151-0 摘要 ( 9652 )   Herein, we report on the synthesis and lithium storage properties of electrospun one-dimensional (1D) CuFe2O4 nanomaterials. 1D CuFe2O4 nanotubes and nanorods were fabricated by a single spinneret electrospinning method followed by thermal decomposition for removal of polymers from the precursor fibers. The as-prepared CuFe2O4 nanotubes with wall thickness of ～50 nm presented diameters of ～150 nm and lengths up to several millimeters. It was found that phase separation between the electrospun composite materials occured during the electrospinning process, while the as-spun precursor nanofibers composed of polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP) and metal salts might possess a core-shell structure (PAN as the core and PVP/metal salts composite as the shell) and then transformed to a hollow structure after calcination. Moreover, as a demonstration of the functional properties of the 1D nanostructure, CuFe2O4 nanotubes and nanorods were investigated as anodes for lithium ion batteries (LIBs). It was demonstrated that CuFe2O4 nanotubes not only delivered a high reversible capacity of ～816 mAh·g-1 at a current density of 200 mA·g-1 over 50 cycles, but also showed superior rate capability with respect to counterpart nanorods. Probably, the enhanced electrochemical performance can be attributed to its high specific surface areas as well as the unique hollow structure.

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Core-shell meso/microporous carbon host for sulfur loading toward applications in lithium-sulfur batteries Juan Zhang, Huan Ye, Yaxia Yin, Yuguo Guo 2014, 23(3): 308-314.  DOI: 10.1016/S2095-4956(14)60152-2 摘要 ( 7783 )   Lithium-sulfur (Li-S) batteries belong to one of the promising technologies for high-energy-density rechargeable batteries. However, sulfur cathodes suffer from inherent problems of its poor electronic conductivity and the shuttling of highly dissoluble lithium polysulfides generated during the cycles. Loading sulfur into porous carbons has been proved to be an effective approach to alleviate these issues. Mesoporous and microporous carbons have been widely used for sulfur accommodation, but mesoporous carbons have poor sulfur confinement, whereas microporous carbons are impeded by low sulfur loading rates. Here, a core-shell carbon, combining both the merits of mesoporous carbon with large pore volume and microporous carbon with effective sulfur confinement, was prepared by coating the mesoporous CMK-3 with a microporous carbon (MPC) shell and served as the carbon host (CMK-3@MPC) to accommodate sulfur. After sulfur infusion, the as-obtained S/(CMK-3@MPC) cathode delivered a high initial capacity of up to 1422 mAh·g-1 and sustained 654 mAh·g-1 reversible specific capacity after 36 cycles at 0.1 C. The good performance is ascribed to the unique core-shell structure of the CMK-3@MPC matrix, in which sulfur can be effectively confined within the meso/microporous carbon host, thus achieving simultaneously high electrochemical utilization.

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Interconnected sandwich structure carbon/Si-SiO2/carbon nanospheres composite as high performance anode material for lithium-ion batteries Yuanjin Du, Mengyan Hou, Dandan Zhou, Yonggang Wang, Congxiao Wang, Yongyao Xia 2014, 23(3): 315-323.  DOI: 10.1016/S2095-4956(14)60153-4 摘要 ( 7082 )   In the present work, an interconnected sandwich carbon/Si-SiO2/carbon nanospheres composite was prepared by template method and carbon thermal vapor deposition (TVD). The carbon conductive layer can not only efficiently improve the electronic conductivity of Si-based anode, but also play a key role in alleviating the negative effect from huge volume expansion over discharge/charge of Si-based anode. The resulting material delivered a reversible capacity of 1094 mAh/g, and exhibited excellent cycling stability. It kept a reversible capacity of 1050 mAh/g over 200 cycles with a capacity retention of 96%.

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Effect of Ni, Fe and Fe-Ni alloy catalysts on the synthesis of metal contained carbon nano-onions and studies of their electrochemical hydrogen storage properties Chenguang Zhang, Jiajun Li, Chunsheng Shi, Chunnian He, Enzuo Liu, Naiqin Zhao 2014, 23(3): 324-330.  DOI: 10.1016/S2095-4956(14)60154-6 摘要 ( 9208 )   Three types of carbon nano-onions (CNOs) including Ni@CNOs, Fe3C@CNOs and Fe0.64Ni0.36@CNOs nanoparticles have been synthesized by catalytic decomposition of methane at 850 ℃using nickel, iron and iron-nickel alloy catalysts. Comparative and systematic studies have been carried out on the morphology, structural characteristics and graphitic crystallinity of these CNOs products. Furthermore, the electrochemical hydrogen storage properties of three types of CNOs have been investigated. Measurements show that the Ni@CNOs have the highest discharge capacity of 387.2 mAh/g, corresponding to a hydrogen storage of 1.42%. This comparison study shows the advantages of each catalyst in the growth of CNOs, enabling the controllable synthesis and tuning the properties of CNOs by mediating different metals and their alloy for using in the fuel cell system.

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Preparation and characterization of Ti0.7Sn0.3O2 as catalyst support for oxygen reduction reaction Yuan Gao, Ming Hou, Zhigang Shao, Changkun Zhang, Xiaoping Qin, Baolian Yi 2014, 23(3): 331-337.  DOI: 10.1016/S2095-4956(14)60155-8 摘要 ( 6662 )   Sn-doped TiO2 nanoparticles with high surface area of 125.7 m2·g-1 are synthesized via a simple one-step hydrothermal method and explored as the cathode catalyst support for proton exchange membrane fuel cells. The synthesized support materials are studied by X-ray diffraction analysis, energy dispersive X-ray spectroscopy and transmission electron microscopy. It is found that the conductivity has been greatly improved by the addition of 30 mol% Sn and Pt nanoparticles are well dispersed on Ti0.7Sn0.3O2 support with an average size of 2.44 nm. Electrochemical studies show that the Ti0.7Sn0.3O2 nanoparticles have excellent electrochemical stability under a high potential compared to Vulcan XC-72. The as-synthesized Pt/Ti0.7Sn0.3O2 exhibits high and stable electrocatalytic activity for the oxygen reduction reaction. The Pt/Ti0.7Sn0.3O2 catalyst reserves most of its electrochemically active surface area (ECA), and its half wave potential difference is 11 mV, which is lower than that of Pt/XC-72 (36 mV) under 10 h potential hold at 1.4 V vs. NHE. In addition, the ECA degradation of Pt/Ti0.7Sn0.3O2 is 1.9 times lower than commercial Pt/XC-72 under 500 potential cycles between 0.6 V and 1.2 V vs. NHE. Therefore, the as synthesized Pt/Ti0.7Sn0.3O2 can be considered as a promising alternative cathode catalyst for proton exchange membrane fuel cells.

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Dispersing SnO2 nanocrystals in amorphous carbon as a cyclic durable anode material for lithium ion batteries Renzong Hu, Wei Sun, Meiqin Zeng, Min Zhu 2014, 23(3): 338-345.  DOI: 10.1016/S2095-4956(14)60156-X 摘要 ( 7101 )   We demonstrate a facile route for the massive production of SnO2/carbon nanocomposite used as high-capacity anode materials of next-generation lithium-ion batteries. The nanocomposite had a unique structure of ultrafine SnO2 nanocrystals (～5 nm, 80 wt%) homogeneously dispersed in amorphous carbon matrix. This structure design can well accommodate the volume change of Li+ insertion/desertion in SnO2, and prevent the aggregation of the nanosized active materials during cycling, leading to superior cycle performance with stable reversible capacity of 400 mAh/g at a high current rate of 3.3 A/g.

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Self-standing rationally functionalized graphene as high-performance electrode materials for supercapacitors Delong Ma, Zhong Wu, Zhanyi Cao 2014, 23(3): 346-353.  DOI: 10.1016/S2095-4956(14)60127-3 摘要 ( 6800 )   Supercapacitors (SCs) have attracted much attention as one of the alternative energy devices due to their high power performance, long cycle life, and low maintenance cost. Graphene is considered as an innovative and promising material due to its large theoretical specific surface area, high electrical conductivity, good mechanical properties and chemical stability. Herein, we report an effective strategy for elaborately constructing rationally functionalized self-standing graphene (SG) obtained from giant graphene oxide (GGO) paper followed by an ultrarapid thermal-processing. This treatment results in both the exfoliation of graphene sheets and the reduction of GGO by elimination of oxygen-containing groups. The as-prepared SG electrode materials without additive and conducting agent provide an excellent combination of the electrical double layer capacitor (EDLC) and pseudocapacitor (PC) functions and exhibit superior electrochemical performance, including high specific capacitance, good rate capability and excellent cycling stability when investigated in three-electrode electrochemical cells.

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Preparation of polypyrrole-coated CuFe2O4 and their improved electrochemical performance as lithium-ion anodes Huayun Xu, Yunpo Wang, Long Zheng, Xinhui Duan, Lihui Wang, Jian Yang, Yitai Qian 2014, 23(3): 354-357.  DOI: 10.1016/S2095-4956(14)60157-1 摘要 ( 6885 )   CuFe2O4 network, prepared via the electrostatic spray deposition technique, with high reversible capacity and long cycle lifetime for lithium ion battery anode material has been reported. The reversible capacity can be further enhanced by coating high electronic conductive polypyrrole (PPy). At the current density of 100 mA·g-1, Li/CuFe2O4 electrode delivers a reversible capacity of 842.9 mAh·g-1 while the reversible capacity of Li/PPy-coated CuFe2O4 electrode increases up to 1106.7 mAh·g-1. A high capacity of 640.7 mAh·g-1 for the Li/PPy-coated CuFe2O4 electrode is maintained in contrast of 398.9 mAh·g-1 for Li/CuFe2O4 electrode after 60 cycles, which demonstrates good electrochemical performance of the composite due to the increase of electronic conductivity. The electrochemical impedance spectroscopy (EIS) further reveals that the Li/PPy-coated CuFe2O4 electrode has a lower charge transfer resistance than the Li/CuFe2O4 electrode.

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SO2-tolerant Pt-MoO3/C catalyst for oxygen reduction reaction Xiao Liu, Hongmin Wang, Siguo Chen, Xueqiang Qi, Huiliang Gao, Yi Hui, Yang Bai, Lin Guo, Wei Ding, Zidong Wei 2014, 23(3): 358-362.  DOI: 10.1016/S2095-4956(14)60158-3 摘要 ( 9819 )   A Pt-MoO3/C catalyst, aimed to eliminate the harmful effect of sulfur dioxide (SO2) on the performance of Pt nanoparticles (NPs) for catalysis of oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFC), is developed and characterized by TEM, XRD and XPS. The results reveal that Pt-MoO3/C catalyst exhibits not only a higher catalytic activity, but also a better SO2 poisoning resistance and a better recovery performance than the commercial Pt/C catalyst does.

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3D amorphous carbon and graphene co-modified LiFePO4 composite derived from polyol process as electrode for high power lithium-ion batteries Guan Wu, Ran Ran, Bote Zhao, Yujing Sha, Chao Su, Yingke Zhou, Zongping Shao 2014, 23(3): 363-375.  DOI: 10.1016/S2095-4956(14)60159-5 摘要 ( 8646 )   Amorphous carbon and graphene co-modified LiFePO4 nanocomposite has been synthesized via a facile polyol process in connection with a following thermal treatment. Various characterization techniques, including XRD, Mössbauer spectra, Raman spectra, SEM, TEM, BET, O2-TPO, galvano charge-discharge, CV and EIS were applied to investigate the phase composition, carbon content, morphological structure and electrochemical performance of the synthesized samples. The effect of introducing way of carbon sources on the properties and performance of LiFePO4/C/graphene composite was paid special attention. Under optimized synthetic conditions, highly crystalized olivine-type LiFePO4 was successfully obtained with electron conductive Fe2P and FeP as the main impurity phases. SEM and TEM analyses demonstrated the graphene sheets were randomly distributed inside the sample to create an open structured LiFePO4 with respect to graphene, while the glucose-derived carbon mainly coated over LiFePO4 particles which effectively connected the graphene sheets and LiFePO4 particles to result in a more efficient charge transfer process. As a result, favorable electrochemical performance was achieved. The performance of the amorphous carbon-graphene co-modified LiFePO4 was further progressively improved upon cycling in the first 200 cycles to reach a reversible specific capacity as high as 97 mAh·g-1 at 10 C rate.

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A ternary phased SnO2-Fe2O3/SWCNTs nanocomposite as a high performance anode material for lithium ion batteries Wangliang Wu, Yi Zhao, Jiaxin Li, Chuxin Wu, Lunhui Guan 2014, 23(3): 376-382.  DOI: 10.1016/S2095-4956(14)60160-1 摘要 ( 7284 )   A new SnO2-Fe2O3/SWCNTs (single-walled carbon nanotubes) ternary nanocomposite was first synthesized by a facile hydrothermal approach. SnO2 and Fe2O3 nanoparticles (NPs) were homogeneously located on the surface of SWCNTs, as confirmed by X-ray diffraction (XRD), transmission electron microscope (TEM) and energy dispersive X-ray spectroscopy (EDX). Due to the synergistic effect of different components, the as synthesized SnO2-Fe2O3/SWCNTs composite as an anode material for lithium-ion batteries exhibited excellent electrochemical performance with a high capacity of 692 mAh·g-1 which could be maintained after 50 cycles at 200 mA·g-1. Even at a high rate of 2000 mA·g-1, the capacity was still remained at 656 mAh·g-1.

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Enhanced high temperature cycling performance of LiMn2O4/graphite cells with methylene methanedisulfonate (MMDS) as electrolyte additive and its acting mechanism Fengju Bian, Zhongru Zhang, Yong Yang 2014, 23(3): 383-390.  DOI: 10.1016/S2095-4956(14)60161-3 摘要 ( 8381 )   The effects of methylene methanedisulfonate (MMDS) on the high-temperature (～50 ℃) cycle performance of LiMn2O4/graphite cells are investigated. By addition of 2 wt% MMDS into a routine electrolyte, the high-temperature cycling performance of LiMn2O4/graphite cells can be significantly improved. The analysis of differential capacity curves and energy-dispersive X-ray spectrometry (EDX) indicates that MMDS decomposed on both cathode and anode. The three-electrode system of pouch cell is used to reveal the capacity loss mechanism in the cells. It is shown that the capacity fading of cells without MMDS in the electrolytes is due to irreversible lithium consumption during cycling and irreversible damage of LiMn2O4 material, while the capacity fading of cell with 2 wt% MMDS in electrolytes mainly originated from irreversible lithium consumption during cycling.

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Sulfur/carbon composites prepared with ordered porous carbon for Li-S battery cathode Xin Zhuang, Yingjia Liu, Jian Chen, Hao Chen, Baolian Yi 2014, 23(3): 391-396.  DOI: 10.1016/S2095-4956(14)60162-5 摘要 ( 8551 )   Ordered porous cabon with a 2-D hexagonal structure, high specific surface area and large pore volume was synthesized through a two-step heating method using tri-block copolymer as template and phenolic resin as carbon precursor. The results indicated the electrochemical performance of the sulfur/carbon composites prepared with the ordered porous carbon was significantly affected by the pore structure of the carbon. Both the specific capacity and cycling stability of the sulfur/carbon composites were improved using the bimodal micro/meso-porous carbon frameworks with high surface area. Its initial discharge capacity can be as high as 1200 mAh·g-1 at a current density of 167.5 mA·g-1. The improved capacity retention was obtained during the cell cycling as well.

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Graphene oxide assisted facile hydrothermal synthesis of LiMn0.6Fe0.4PO4 nanoparticles as cathode material for lithium ion battery Changchang Xu, Li Li, Fangyuan Qiu, Cuihua An, Yanan Xu, Ying Wang, Yijing Wang, Lifang Jiao, Huatang Yuan 2014, 23(3): 397-402.  DOI: 10.1016/S2095-4956(14)60163-7 摘要 ( 7428 )   Assisted by graphene oxide (GO), nano-sized LiMn0.6Fe0.4PO4 with excellent electrochemical performance was prepared by a facile hydrothermal method as cathode material for lithium ion battery. SEM and TEM images indicate that the particle size of LiMn0.6Fe0.4PO4 (S2) was about 80 nm in diameter. The discharge capacity of LiMn0.6Fe0.4PO4 nanoparticles was 140.3 mAh·g-1 in the first cycle. It showed that graphene oxide was able to restrict the growth of LiMn0.6Fe0.4PO4 and it in situ reduction of GO could improve the electrical conductivity of LiMn0.6Fe0.4PO4 material.

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TiO2 nanocrystals/graphene hybrids with enhanced Li-ion storage performance Qingqing Zhang, Rong Li, Mengmeng Zhang, Bianli Zhang, Xinglong Gou 2014, 23(3): 403-410.  DOI: 10.1016/S2095-4956(14)60164-9 摘要 ( 7399 )   TiO2 nanocrystals/graphene hybrids (TiO2-G) with ultrafine TiO2 nanocrystals (～7 nm in size) conformally coated on ultrathin graphene nanosheets (～2 layers thick) were successfully prepared via a facile one-pot solvothermal route under mediated conditions. With the feature of large surface area, abundant mesopores and high thermal stability, the TiO2-G nanohybrids exhibited large reversible Li-ion storage capacity with excellent cycling stability (629 mAh·g-1 after 400 cycles at a current of 60 mA·g-1) and good rate capability (184 mAh·g-1 at a current density of 3 A·g-1) due to the synergetic effects and strong interactions between the components, showing great promise in applications for advanced energy storage devices.