Large reversible Li storage of graphene nanosheet families for use in rechargeable lithium ion batteries

The lithium storage properties of graphene nanosheet (GNS) materials as high capacity anode materials for rechargeable lithium secondary batteries (LIB) were investigated. Graphite is a practical anode material used for LIB, because of its capability for reversible lithium ion intercalation in the layered crystals, and the structural similarities of GNS to graphite may provide another type of intercalation anode compound. While the accommodation of lithium in these layered compounds is influenced by the layer spacing between the graphene nanosheets, control of the intergraphene sheet distance through interacting molecules such as carbon nanotubes (CNT) or fullerenes (C60) might be crucial for enhancement of the storage capacity. The specific capacity of GNS was found to be 540 mAh/g, which is much larger than that of graphite, and this was increased up to 730 mAh/g and 784 mAh/g, respectively, by the incorporation of macromolecules of CNT and C60 to the GNS.     

Electrochemical characterizations of Li2.6Co0.4N/Graphite anodes for lithium ion batteries

Li_2.6Co_0.4N anode material was prepared by solid-state reaction. The material was used to prepare Li_2.6Co_0.4N/natural graphite composite anode materials with the aim to improve the electrochemical performance of natural graphite. Natural graphite showed a low initial columbic efficiency of 69%, which was improved to ~ 100% by adding 20 wt.% of Li_2.6Co_0.4N into the material. On the other hand, the composite materials showed better capacity retention than both pure Li_2.6Co_0.4N and natural graphite. The material containing 20 wt.% of Li_2.6Co_0.4N exhibited a reversible discharge capacity of 243 mAh g^? 1 after thirty cycles, as compared to a capacity of 212 mAh g^? 1 for natural graphite.     

锂离子电池负极材料Li4Ti5O12的合成及电化学性能

采用高温固相反应法制备尖晶石相Li4Ti5O12负极材料.初步研究了反应温度和反应时间对Li4Ti5O12电化学性能的影响.XRD衍射未观测到TiO2残余存在;电化学测试显示,1.2～2.5V恒流充放电,其可逆容量达158.3mAh/g,首次库仑效率为95.2%;循环20周其容量衰减率仅为3.1%.     

Controlled Ag-driven superior rate-capability of Li4Ti5O12 anodes for lithium rechargeable batteries

The morphology and electronic structure of a Li₄Ti₅O₁₂ anode are known to determine its electrical and electrochemical properties in lithium rechargeable batteries. Ag-Li₄Ti₅O₁₂ nanofibers have been rationally designed and synthesized by an electrospinning technique to meet the requirements of one-dimensional (1D) morphology and superior electrical conductivity. Herein, we have found that the 1D Ag-Li₄Ti₅O₁₂ nanofibers show enhanced specific capacity, rate capability, and cycling stability compared to bare Li₄Ti₅O₁₂ nanofibers, due to the Ag nanoparticles (<5 nm), which are mainly distributed at interfaces between Li₄Ti₅O₁₂ primary particles. This structural morphology gives rise to 20% higher rate capability than bare Li₄Ti₅O₁₂ nanofibers by facilitating the charge transfer kinetics. Our findings provide an effective way to improve the electrochemical performance of Li₄Ti₅O₁₂ anodes for lithium rechargeable batteries.      

Lithiophilic N-doped carbon bowls induced Li deposition in layered graphene film for advanced lithium metal batteries

Lithium(Li)metal with high theoretical capacity and low electrochemical potential is the most ideal anode for next-generation high-energy batteries.However,the practical implementation of Li anode has been hindered by dendritic growth and volume expansion during cycling,which results in low Coulombic efficiency(CE),short lifespan,and safety hazards.Here,we report a highly stable and dendrite-free Li metal anode by utilizing N-doped hollow porous bowl-like hard carbon/reduced graphene nanosheets(CB@rGO)hybrids as three-dimensional(3D)conductive and lithiophilic scaffold host.The lithiophilic carbon bowl(CB)mainly works as excellent guides during the Li plating process,whereas the rGO layer with high conductivity and mechanical stability maintains the integrity of the composite by confining the volume change in long-range order during cycling.Moreover,the local current density can be reduced due to the 3D conductive framework.Therefore,CB@rGO presents a low lithium metal nucleation overpotential of 18 mV,high CE of 98%,and stable cycling without obvious voltage fluctuation for over 600 cycles at a current density of 1 mA cm^-2.Our study not only provides a good CB@rGO host and pre-Lithiated CB@rGO composite anode electrode,but also brings a new strategy of designing 3D electrodes for those active materials suffering from severe volume expansion.     

锂离子电池电解质用含硼锂盐研究进展

电解质材料是锂离子电池的关键材料之一。LiBF4、双草酸硼酸锂(LiBOB)及草酸二氟硼酸锂(LiODFB)是极具应用前景的3种含硼锂盐。介绍了3种锂盐各自的优缺点及研究近况,重点综述了它们的离子传导特性及与电极材料的相容性能。     

Enhanced Al/Ta co-doped Li7La3Zr2O12 ceramic electrolytes with the reduced Ta doping level for solid-state lithium batteries

Garnet Li₇La₃Zr₂O₁₂ (LLZO) is a promising solid-state electrolyte (SSE) candidate for advanced solid-state lithium batteries (SSLBs). In this work, Li_6.25La₃Zr_2-yAl_xTa_yO₁₂ (x?=?0.25, y?=?0; x?=?0.2, y?=?0.15; x?=?0.15, y?=?0.3; x?=?0.1, y?=?0.45; x?=?0.05, y?=?0.6) and Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZT_0.6O) ceramic electrolytes, are prepared via a simple sol–gel process. The effect of Al and Ta co-doping levels on the phase, the microstructure and the ionic conductivity of modified LLZO is discussed in detail. Those Al/Ta co-doped LLZO ceramics (LLZATO) with Ta?≥?0.3 per formula unit, are nearly pure cubic structures with a trace of new phases. The ionic conductivities of Li_6.25La₃Zr_1.55Al_0.1Ta_0.45O₁₂ (LLZA_0.1T_0.45O) and Li_6.25La₃Zr_1.4Al_0.05Ta_0.6O₁₂ (LLZA_0.05T_0.6O), are greatly improved by co-doping Al and Ta, benefitting from the emergence of self-grown LiAlO₂ phase, and the microstructure of large grains contacting small grains. Remarkably, the optimal LLZA_0.1T_0.45O delivers a high ionic conductivity of 6.70?×?10^–4 S cm^?1 and a low electronic conductivity?~?9.83?×?10^–8 S cm^?1 at 25 °C. This work provides available enhanced Al/Ta co-doped LLZO ceramic electrolytes with the reduced Ta doping level for solid-state lithium batteries.

     

Rocking-chair or lithium-ion rechargeable lithium batteries

Owing to the present exponential development of portable consumer electronics and to the increasing concern about the environment, new energy sources are required that provide more energy in the same volume and/or mass. Within a short period of time, less than three years, many changes in the area of rechargeable batteries for the consumer market have occurred, along with the emergence of several new technologies. The ubiquitous Ni? Cd cells, which are environmentally unfriendly because of the toxicity of Cd, will be replaced by Ni-metal hydride, rocking-chair lithium (or Li-ion), and lithium polymer electrolyte rechargeable cells. This paper reviews recent advances in the field of Li-ion rechargeable batteries.     

新型硅-硫锂电池研究进展

高比能量、高安全性是未来储能系统的重要发展方向,在电子产品、航天设备、高续航电动汽车等诸多领域均有迫切需求。硅具有很高的理论比容量,电压平台接近金属锂,采用硅替代锂金属作为负极可以得到新型硅-硫锂电池。本文阐述了新型硅-硫锂电池的特征及存在的关键问题,介绍了全电池中锂源的引入方式,综述了新型硅-硫锂电池正、负极的制备技术及研究进展,总结了不同制备方法存在的优缺点,并详述了目前液态电解质的常见组成、研究进展以及存在的问题。最后结合硅-硫锂电池的发展趋势提出未来重点研究的几个方向,如优化电极/电解质界面、开发固态电解质等。     

Nanocomposite quasi-solid-state electrolyte for high-safety lithium batteries

Rechargeable lithium batteries are attractive power sources for electronic devices and are being aggressively developed for vehicular use. Nevertheless, problems with their safety and reliability must be solved for the large-scale use of lithium batteries in transportation and grid-storage applications. In this study, a unique hybrid solid-state electrolyte composed of an ionic liquid electrolyte (LiTFSI/Pyr₁₄TFSI) and BaTiO3 nanosize ceramic particles was prepared without a polymer. The electrolyte exhibited high thermal stability, a wide electrochemical window, good ionic conductivity of 1.3 × 10^?3 S·cm^?1 at 30 °C, and a remarkably high lithium-ion transference number of 0.35. The solid-state LiFePO₄ cell exhibited the best electrochemical properties among the reported solid-state batteries, along with a reasonable rate capability. Li/LiCoO₂ cells prepared using this nanocomposite solid electrolyte exhibited high performance at both room temperature and a high temperature, confirming their potential as lithium batteries with enhanced safety and a wide range of operating temperatures.

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Intercalation of lithium from Al–Li alloys into lithium titanates

Abstract

An investigation was carried out into the possibility of removing lithium from molten aluminium using insertion compounds. The compounds selected were Li₂O. 3TiO₂ and Li₂O. 2·5 TiO₂ and the structure and degree of insertion were studied. It was found that lithium could be incorporated into the structure, then removed electrochemically.

MST/735     

Dendrite-free all-solid-state lithium batteries with lithium phosphorous oxynitride-modified lithium metal anode and composite solid electrolytes

Nano Research - Dendrite formation on lithium (Li) metal anode is a key issue which hinders the development of rechargeable Li battery seriously. A novel method for suppressing Li dendrites via...     

锂离子二次电池负极材料的研究综述

总结了在碳材料、合金材料和复合材料等3个锂离子电池负极材料研发的主导方向上的开发情况和它们各自特点,描述了目前的研究所面临难题,给出了锂离子电池负极材料研发取得重大突破的可能途径和建议.