Ge-doped Li4Ti5-xGexO12 (x = 0.05) as a fast-charging,long-life bi-functional anode material for lithium- and sodium-ion batteries

We explored the doping effect of Ge⁴⁺ on the Li₄Ti_5-xGe_xO₁₂ (x = 0.0 and 0.05) anode material by looking at its electrochemical performance in both Li- and Na-ion batteries. Combined analysis using Rietveld refinement of high-resolution powder diffraction (HRPD) and transmission electron microscopy (TEM) unambiguously identified homogeneous Ge doping into the 16c octahedral Ti site of the Li₄Ti₅O₁₂ (LTO) cubic spinel structure. This Ge doping leads to a much-reduced particle size, slightly expanded lattice and increased electrical conductivity due to the increased Ti³⁺ to Ti⁴⁺ ratio, these results were verified by HRPD, scanning electron microscopy (SEM), 4-point probe and x-ray photoelectron spectroscopy (XPS) analysis. The Li₄Ti_4.95Ge_0.05O₁₂ (Ge0.05-LTO) electrode shows much-improved capacity, high-rate capability and excellent cycling stability in a Li-half cell compared with an un-doped LTO electrode. This performance improvement is due to the reduced Li⁺ diffusion path and faster Li⁺ insertion/extraction kinetics that originate from Ge doping. In addition to these results, when tested as an anode for SIBs, the Ge0.05-LTO electrode exhibits enhanced capacity and cycling stability compared to un-doped LTO electrode, demonstrating its bi-functional, advantageous features in both LIB and SIB systems.     

5V高电压锂离子电池阴极材料研究进展

先锂离子二次电池是在当今社会有着非常重要应用的能量储存一转换设备。随着电池材料性能的不断改进,锂电池也越来越可能取代石油等传统燃料而为汽车等交通工具提供动力。但是,要最终达到这一应用目标,要求电池材料有更高的能量密度,这也成为最近几年各国争先突破的研究热点。本文综述了5V高电压高能量密度锂离子二次电池阴极材料的最新研究进展,阐述了发展高电压高能量密度锂离子二次电池材料所面临的重要问题和挑战,并系统地总结了几种最有潜力的5V高电压阴极材料的研究进展。     

Interface-modulated approach toward multilevel metal oxide nanotubes for lithium-ion batteries and oxygen reduction reaction

Metal oxide hollow structures with multilevel interiors are of great interest for potential applications such as catalysis,chemical sensing,drug delivery,and energy storage.However,the controlled synthesis of multilevel nanotubes remains a great challenge.Here we develop a facile interface-modulated approach toward the synthesis of complex metal oxide multilevel nanotubes with tunable interior structures through electrospinning followed by controlled heat treatment.This versatile strategy can be effectively applied to fabricate wire-in-tube and tubein-tube nanotubes of various metal oxides.These multilevel nanotubes possess a large specific surface area,fast mass transport,good strain accommodation,and high packing density,which are advantageous for lithium-ion batteries (LIBs)and the oxygen reduction reaction (ORR).Specifically,shrinkable CoMn2O4 tube-in-tube nanotubes as a lithium-ion battery anode deliver a high discharge capacity of ～565 mAh.g-1 at a high rate of 2 A.g-1,maintaining 89％ of the latter after 500 cycles.Further,as an oxygen reduction reaction catalyst,these nanotubes also exhibit excellent stability with about 92％ current retention after 30,000 s,which is higher than that of commercial Pt/C (81％).Therefore,this feasible method may push the rapid development of one-dimensional (1D) nanomaterials.These multifunctional nanotubes have great potential in many frontier fields.     

Ionic Liquid‐Directed Nanoporous TiNb2O7 Anodes with Superior Performance for Fast‐Rechargeable Lithium‐Ion Batteries

Nanoporous TiNb₂O₇ (NPTNO) material is synthesized by a sol–gel method with an ionic liquid (IL) as the nanoporous structure directing template. NPTNO exhibits a high reversible capacity of 210 mAh g^–1 even at the charging rate of 50 C and an excellent cyclability of half‐cell capacity retention of 74% for 1000 cycles at 5 C and LiNi_0.5Mn_1.5O₄‐coupled full‐cell capacity retentions of 81% and 87% for 1000 cycles at 1 C and 2 C, respectively. The studies of the 1000 cycled NPTNO electrode illustrate that the IL‐directed mesoporous structure can enhance the cyclability of NPTNO cells due to the alleviation of repetitive mechanical stress and volume fluctuation induced by the repetitive Li⁺ insertion‐extraction processes. The measured Li⁺ diffusion coefficients from the galvanostatic intermittent titration technique suggest that the IL‐templating strategy indeed ensures the fast rechargeability of NPTNO cells based on the fast Li⁺ diffusion kinetics. Benefitting from the nanoporous structure, NPTNO with unhindered Li⁺ diffusion pathways achieves a superior rate capability in the titanium‐based oxide materials and the best full‐cell cyclability in the TNO materials. Therefore, the templating potential of IL is demonstrated, and the superb electrochemical performance establishes the IL‐directed NPTNO as a promising anode candidate for fast‐rechargeable LIBs.     

LIB separators and the recent technical progress

介绍了锂电池隔膜的功能及影响其性能的因素.总结了近十年来在锂电隔膜研发和技术领域的热点,即高安全性,新材料,陶瓷涂覆和提高润湿性等.分析了包括3C锂电池及动力锂电池等两类电池对隔膜性能的要求,指出了3C锂离子电池隔膜需要往厚度更薄,孔隙率更高,耐热温度更高,均匀性更好等方向发展,动力锂电池则着重于提高能量密度,扩大电化学稳定窗口,提升耐高电压特性.并从聚烯烃改性,聚烯烃-陶瓷复合隔膜,新材料体系,新工艺方法等方面介绍了隔膜领域的主要技术进展.最后,分析并展望了我国隔膜产业的现状,指出在提高产能的同时,应更加注重对技术及工艺的自主研发以保证产品质量.     

基于IEEE802.15.4CSMA/CA机制的无线传感网络实时性能改进

自从IEEE802.15.4标准发布以来,低功耗、低速率传输的无线传感器网络的应用几乎涉及到现实生活的方方面面,而对这个标准的CSMA/CA机制实时性分析大部分都是基于BEB退避机制的分析.针对非饱和的CSMA/CA机制,提出了1种改进实时性能的退避机制LIB,采用马尔可夫链详细分析节点的访问过程和信道状态,并且基于这...     

Wet‐Chemical Synthesis of Hollow Red‐Phosphorus Nanospheres with Porous Shells as Anodes for High‐Performance Lithium‐Ion and Sodium‐Ion Batteries

Large‐volume‐expansion‐induced material pulverization severely limits the electrochemical performance of red phosphorous (P) for energy‐storage applications. Hollow nanospheres with porous shells are recognized as an ideal structure to resolve these issues. However, a chemical synthetic approach for preparing nanostructured red P is always of great challenge and hollow nanosphere structures of red P have not yet been fabricated. Herein, a wet solvothermal method to successfully fabricate hollow P nanospheres (HPNs) with porous shells via a gas‐bubble‐directed formation mechanism is developed. More importantly, due to the merits of the porous and hollow structures, these HPNs reveal the highest capacities (based on the weight of electrode materials) of 1285.7 mA h g^?1 for lithium‐ion batteries and 1364.7 mA h g^?1 for sodium‐ion batteries at 0.2 C, and excellent long‐cycling performance.     

电动汽车用锂离子蓄电池的研究

研制了55Ah圆柱型动力锂离子蓄电池以及336V/55Ah动力模块和相应的电池管理系统。性能测试表明,0.5C充放电,单体电池容量≥55Ah,容量特性均匀一致;具备良好的倍率放电特性,能够适应电动车启动、加速、爬坡等运行要求;循环性能良好,已完成200次深充放循环性能仍平稳;耐滥用能力好;84只单体构成的电池组,比能量达106Wh/kg;安全性好。充放电管理系统采用阶段恒电流充电和过流保护,具备均衡充电能力和智能调节放电终止电压和剩余容量显示等功能。装车试验表明,该电池系统有望投入电动车的实际应用。