Dispersing SnO2 nanocrystals in amorphous carbon as a cyclic durable anode material for lithium ion batteries

We demonstrate a facile route for the massive production of SnCb/carbon nanocomposite used as high-capacity anode materials of nextgeneration 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.     

Nb2O5-carbon core-shell nanocomposite as anode material for lithium ion battery

Nb₂O₅-carbon nanocomposite is synthesized through a facile one-step hydrothermal reaction from sucrose as the carbon source, and studied as an anode material for high-performance lithium ion battery. The structural characterizations reveal that the nanocomposite possesses a core-shell structure with a thin layer of carbon shell homogeneously coated on the Nb₂O₅ nanocrystals. Such a unique structure enables the composite electrode with a long cycle life by preventing the Nb₂O₅ from volume change and pulverization during the charge-discharge process. In addition, the carbon shell efficiently improves the rate capability. Even at a current density of 500 mA·g^?1, the composite electrode still exhibits a specific capacity of ～100 mAh·g^?1. These results suggest the possibility to utilize the Nb₂O₅-carbon core-shell composite as a high performance anode material in the practical application of lithium ion battery.     

中间相Si-Cu合金作为锂离子电池负极材料的第一性原理研究

采用第一性原理平面波赝势法,对中间相Si-Cu合金作为锂离子电池负极材料的嵌脱锂机理进行研究.结果表明,4个Si-Cu合金相中Si0.125Cu0.875合金相具有最低的体积膨胀系数及最低的嵌锂电位,导电性在4个合金相中排第二位,具有最佳的电化学综合性能.     

Synthesis of carbon nanofibers@MnO2 3D structures over copper foil as binder free anodes for lithium ion batteries

A 3D structured composite of carbon nanofibers@MnO₂ on copper foil is reported here as a binder free anode of lithium ion batteries, with high capacity, fast charge/discharge rate and good stability. Carbon nanofiber yarns were synthesized directly over copper foil through a floating catalyst method. The growth of carbon nanofiber yarns was significantly enhanced by mechanical polishing of the copper foils, which can be attributed to the increased surface roughness and surface area of the copper foils. MnO₂ was then grown over carbon nanofibers through spontaneous reduction of potassium permanganate by the carbon nanofibers. The obtained composites of carbon nanofibers@MnO₂ over copper foil were tested as an anode in lithium ion batteries and they show superior electrochemical performance. The initial reversible capacity of carbon nanofibers@MnO₂ reaches up to around 998 mAh·g^?1 at a rate of 60 mmA·g^?1 based on the mass of carbon nanofibers and MnO₂. The carbon nanofibers@MnO₂ electrodes could deliver a capacity of 630 mAh·g^?1 at the beginning and maintain a capacity of 440 mmAh·g^?1 after 105 cycles at a rate of 600 mA·g^?1. The high initial capacity can be attributed to the presence of porous carbon nanofiber yarns which have good electrical conductivity and the MnO₂ thin film which makes the entire materials electrochemically active. The high cyclic stability of carbon nanofibers@MnO₂ can be ascribed to the MnO₂ thin film which can accommodate the volume expansion and shrinking during charge and discharge and the good contact of carbon nanofibers with MnO₂ and copper foil.     

Improved disordered carbon as high performance anode material for lithium ion battery

A sulfur-substituted disordered carbon is explored as anode material for lithium-ion battery. Its physical and electrochemical properties are characterized by a variety of techniques such as powder X-ray diffraction, element analysis, Fourier transform infrared spectrum, scanning electron microscopy, and typical electrochemical tests. Electrochemical tests show the activated carbon displays a first cycle discharge capacity of 1,216 mAh·g⁻¹. It also has a remarkable cycling stability with an average capacity fade of 0.92% per cycle from 11th to 100th cycle in the range of 0.01–3.00 V versus metallic lithium at a current density of 100 mA·g⁻¹. After 100 cycles, the electrode still maintained a capacity of 420 mAh·g⁻¹.     

锂离子电池锡基复合氧化物负极材料的研究

采用共沉淀法制备了SnSbO2.5和SnGeO3两种锡基复合氧化物粉末.XRD分析表明,这两种锡基复合氧化物的共同特点是在27°～28°处有波峰,属无定型结构.将其分别作为锂离子电池负极材料的活性物质,利用恒电流电池测试仪研究它们的电化学性能.实验表明,这两种锡基复合氧化物都有较高的电化学容量,SnSbO2.5的可逆容量为1200mA·h/g,SnGeO3的可逆容量为750mA·h/g.这两种锡基复合氧化物的电化学容量远高于碳材料(石墨的理论容量为372mA·h/g),因此,这两种锡基复合氧化物可以作为锂离子电池负极材料的候选材料.     

锂离子二次电池碳负极材料的改性

作为锂离子二次电池的碳负极材料，其改性方面的研究内容主要有：引入非金属元素，引入金属元素，处理表面及其它方面。纺入的非金属元素有硼，硅，氮，磷和硫。引入的金属元素有钾，铝，镓和钒，镍，钴，铜，铁等过渡金属元素。表面处理的方法包括氧化，形成表面层等。     

熔融浸渍法制备锂离子电池正极材料LiMn2O4的研究

采用LiNO3和MnO2为原料,在650℃下制备了尖晶石型的LiMn2O4.通过X射线衍射、扫描电子显微镜、热重分析和电化学性能测试,发现该化合物具有很高的放电比容量和较好的循环性能,首次放电比容量可达到122 mA·h/g.并对循环性能衰减的各种因素进行了讨论.     

Hydrothermal exfoliated molybdenum disulfide nanosheets as anode material for lithium ion batteries

Ultrathin MoS2nanosheets were prepared in high yield using a facile and effective hydrothermal intercalation and exfoliation route. The products were characterized in detail using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The results show that the high yield of MoS2nanosheets with good quality was successfully achieved and the dimensions of the immense nanosheets reached 1 μm–2 μm. As anode material for Li-ion batteries, the as-prepared MoS2nanosheets electrodes exhibited a good initial capacity of 1190 mAh g-1and excellent cyclic stability at constant current density of 50 mA g-1. After 50 cycles, it still delivered reversibly sustained high capacities of 750 mAh g-1.     

Hydrothermal exfoliated molybdenum disulfidenanosheets as anode material for lithium ion batteries

Ultrathin MoS2nanosheets were prepared in high yield using a facile and effective hydrothermal intercalation and exfoliation route. The products were characterized in detail using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The results show that the high yield of MoS2nanosheets with good quality was successfully achieved and the dimensions of the immense nanosheets reached 1 μm–2 μm. As anode material for Li-ion batteries, the as-prepared MoS2nanosheets electrodes exhibited a good initial capacity of 1190 mAh g-1and excellent cyclic stability at constant current density of 50 mA g-1. After 50 cycles, it still delivered reversibly sustained high capacities of 750 mAh g-1.     

锂离子电池负极材料铜锌锡硫纳米颗粒的制备及其电化学性能

以金属氯化物为金属源,硫脲为硫源,聚乙二醇和乙二醇为混合溶剂,采用溶剂热法一步合成了球形的铜锌锡硫纳米颗粒.利用X射线衍射仪(XRD),扫描电子显微镜(SEM)和透射电子显微镜(TEM)分析了铜锌锡硫纳米颗粒的物相、结构、形貌;利用电池测试系统对以铜锌锡硫纳米颗粒为锂离子电池负极材料组装的锂离子电池的电化学性能进行了测试.结果表明:所得到的产物为具有锌黄锡矿结构的纯相铜锌锡硫,颗粒直径在300～500nm.铜锌锡硫纳米颗粒作为锂离子电池的负极材料具有较好的稳定性,有望在锂离子电池研究和应用中得到推广.     

高产率/低成本制备一维纳米结构负极材料及其在锂离子电池中的应用

锂离子电池的性能在很大程度上由其电极材料决定.目前,商用的锂离子电池负极材料主要为石墨,其性能并不能满足下一代大容量/高功率锂电池的需求.尽管科研工作者在新型锂离子电池负极材料方面做了大量的研究,但距离其大规模应用仍然有诸多问题需要解决,其中最重要的问题之一为实现其高产率/低成本的规模化制备.本文重点介绍了本课题组在一维纳米结构负极材料规模化制备方面取得的进展,包括一维多孔三氧化二铁/四氧化三钴、一维多孔草酸盐和一维多孔铁酸锌.     

Nitrogen-doped carbon nanotubes by multistep pyrolysis process as a promising anode material for lithium ion hybrid capacitors

Lithium-ion hybrid capacitors (LIHCs) is a promising electrochemical energy storage devices which combines the advantages of lithium-ion batteries and capacitors. Herein, we developed a facile multistep pyrolysis method, prepared an amorphous structure and a high-level N-doping carbon nanotubes (NCNTs), and by removing the Co catalyst, opening the port of NCNTs, and using NCNTs as anode material. It is shows good performance due to the electrolyte ions enter into the electrode materials and facilitate the charge transfer. Furthermore, we employ the porous carbon material (APDC) as the cathode to couple with anodes of NCNTs, building a LIHCs, it shows a high energy density of 173 Wh/kg at 200 W/kg and still retains 53 Wh/kg at a high power density of 10 kW/kg within the voltage window of 0–4.0 V, as well as outstanding cyclic life keep 80% capacity after 5000 cycles. This work provides an opportunity for the preparation of NCNTs, that is as a promising high-performance anode for LIHCs.     

Nano-structured phosphorus composite as high-capacity anode materials for lithium batteries

More than LiP service: The adsorption of red phosphorus into porous carbon provides a composite anode material for lithium-ion batteries. The amorphous nano phosphorus, in the carbon matrix, shows highly reversible lithium storage with high coulombic efficiencies and stable cycling capacity of 750?mAh per gram composite.     

Carbon anode materials from polysiloxanes for lithium ion batteries

Three kinds of silicon-containing disordered carbons have been prepared by pyrolysis of polysiloxanes with different amounts of phenyl side groups. X-ray powder diffraction, X-ray photoelectron spectroscopy and electrochemical capacity measurements were performed to study their behaviors. Graphite crystallites, micropores, and silicon species affect their electrochemical performances. All of them present high reversible capacities, >372 mAh/g. Since the graphite crystallites are very small, they contribute very little to reversible capacity. The number of micropores produced by gas emission during the heat-treatment process decides whether they exhibit reversible capacity. Si mainly exists in the form C–Si–O and influences the irreversible capacity. There is no evident capacity fading in the first ten cycles, indicating promising properties for these disordered carbons.     

Synthesis of nanoporous silica aerogel by ambient pressure drying

A crack-free silica aerogel monolith was fabricated from a cheap water glass derived silicic acid solution by adding glycerol, which served as a drying control chemical additive (DCCA). The OH surfaces of the wet gel with glycerol were modified using a TMCS/n-hexane mixture followed by solvent exchange from water to n-hexane. The obtained surface modified wet gel was dried at 75 °C under ambient pressure. The addition of glycerol appears to give the wet gel a more homogeneous microstructure (larger pore size and uniform size distribution) as well as enhanced stiffness. However, glycerol also retards surface modification and solvent exchange. The aerogel synthesized with glycerol added to the silica sol maintained a relatively low bulk density compared with the aerogels aged in a mixed ethanol (EtOH)/TEOS solution. The reproducibility of aerogel production was further improved in the aerogel synthesized with glycerol added to the silica sol and aged in a 70%EtOH/30%TEOS solution.     

A ternary phased SnO2-Fe2O3/SWCNTs nanocomposite as a high performance anode material for lithium ion batteries

A new SnO_2-Fe_2O_3/SWCNTs(single-walled carbon nanotubes) ternary nanocomposite was first synthesized by a facile hydrothermal approach.SnO_2 and Fe_2O_3 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 SnO_2-Fe_2O_3/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 of2000 mA·g~(-1),the capacity was still remained at 656 mAh·g~(-1).     

Studies of Nano－sized Co304 as Anode Materials for Lithium－ion Batteries

The structural evolution of the Co₃O₄ fine powders prepared by rheological phase reaction and pyrolysis method upon different temperature has been investigated using X‐ray diffraction (XRD) topography. The electrochemical performance of Co₃O₄ electrode materials for Li‐ion batteries is studied in the form of Li/Co₃O₄ cells. The reversible capacity as high as 930 mAh/g for the Co₃O₄ sample heat‐treated at 600 °C is achieved and sustained over 30 times charge‐discharge cycles at room temperature. The detailed information concerning the reaction mechanism of Co₃O₄ active material together with lithium ion is obtained through ex‐situ XRD topography, X‐ray photoelectron spectroscopy (XPS) analysis and cyclic voltammetry (CV) technique. And it is revealed that a “two‐step” reaction is involved in the charge and discharge of the Li/Co₃O₄ cells, in which Co₃O₄ active material is reversibly reduced into xCoO(3 ‐ x)CoO and then into metallic Co.     

共轭微孔聚合物热解制备氮、硫杂原子硬炭及其储锂性能

选取溴代噻唑和三乙炔基苯为单体,利用聚合反应自下而上构建含噻唑共轭微孔聚合物(NSCMP),通过热解和KOH活化热解NSCMP制备了氮、硫杂原子硬炭(NSHC)和活化NSHC(KNSHC)。利用扫描电子显微镜、能量色散谱、氮气吸附-脱附和恒流充放电等表征2个样品的结构与电化学性能。研究表明KNSHC中N和S的质量分数分别为10.42%和2.23%,KNSHC比表面积高达2 140 m²·g^-1。在0.2 A·g^-1电流密度下循环500次后KNSHC和NSHC的可逆比容量分别为946.2和493.7 mAh·g^-1。KNSHC的优异电化学性能归因于其独特的孔结构和氮、硫杂原子的协同作用。