Thermomechanical analysis and durability of commercial micro-porous polymer Li-ion battery separators

Static and dynamic thermomechanical analysis was performed with a dynamic mechanical analyzer (DMA) to identify thermal and mechanical transitions for commercially available polymer separators under mechanical loading. Clear transitions in deformation mode were observed at elevated temperatures. These transitions identified the onset of separator “shutdown” which occurred at temperatures below the polymer melting point. Mechanical loading direction was critical to the overall integrity of the separator. Anisotropic separators (Celgard 2320, 2400 and 2500) were mechanically limited when pulled in tensile in the transverse direction. The anisotropy of these separators is a result of the dry technique used to manufacture the micro-porous membranes. Separators prepared using the wet technique (Entek Gold LP) behaved more uniformly, or biaxially, where all mechanical properties were nearly identical within the separator plane. The information provided by the DMA can also be useful for predicting the long-term durability of polymer separators in lithium-ion batteries exposed to electrolyte (solvent and salt), thermal fluctuations and electrochemical cycling. Small losses in mechanical integrity were observed for separators exposed to the various immersion environments over the 4-week immersion time.     

New covalent salts of the 4+ V class for Li batteries

There is urgent action required for replacing LiPF₆ as a solute for Li-ion batteries electrolytes. This salt, prone to highly Lewis acidic PF₅ release and hydrolysis to HF is responsible for deleterious reaction on carbonate solvents, corrosion of electrode materials leading to safety problems then release to toxic chemicals. A major advantage of LiPF₆ is that it passivates aluminium. Most attempts to replace LiPF₆ with hydrolytically-stable salts have been unsuccessful because of Al corrosion.We present here two “Hückel” type salts, namely lithium (2-fluoroalkyl-4,5-dicyano-imidazolate); fluoroalkyle = CF₃ (TDI), C₂F₅ (PDI) with high charge delocalization. These thermally stable salts give both appreciably conductive solutions in EC/DMC (>6 mS cm⁻¹ at 20 °C) with a lower decrease with temperature than LiPF₆. Non fluorinated lithium (4,5-dicyano-1,2,3-triazolate) is comparatively less than half as conductive. The lithium transference number T₊ measured by PFG-NMR is also higher. Voltammetry scans with either platinum or aluminium electrodes show an oxidation wall at 4.6 V versus Li⁺:Li°. These two salts are thus the first examples of strictly covalent, non-corroding salts allowing 4+ V electrode material operation. This is demonstrated with experimental Li/LiMn₂O₄ cells as beyond the third cycles, the fade of the three electrolytes were quasi-identical, though LiPF₆ had a sharper initial decrease.     

UPS蓄电池ABM智能充电管理初探

文中着重研究了单片机控制的UPS蓄电池的ABM智能充电管理控制技术及实现,分析了系统的工作原理,给出了硬件实现电路和算法框图,以及ABM智能充电管理与普通充电的比较结果,该结果验证了其优越性。     

提高牵引用铅酸蓄电池循环耐久能力的途径及措施

简述了影响牵引用铅酸蓄电池循环耐久能力的几个主要问题，认为提高正板骨架、套管及隔板的耐腐性能，抑制负机板膨胀及活物质脱落是改进这种电池循环耐久能力的关键。     

汽车用36 V蓄电池的发展及有关技术问题的分析

介绍了42V电压汽车电器系统及配套需要的36V蓄电池,对36V蓄电池的开发和生产面临的技术问题进行了分析.     

解决电动自行车用蓄电池问题的系统方法

概述了目前电动自行车的使用状态和存在的问题，认为必须将蓄电池自身的问题及消除消费者对蓄电池品质的心理障碍看成一个核心问题，并从市场实践中探索出一种解决这个核心问题的系统工程方法。     

电池生产废水治理的研究

电池生产的废水中含有大量的Ｚｎ＾２＋、Ｍｎ＾２＋，Ｈｇ＾２＋等重金属离子，如果不加治理排放，则将对环境造成污染。以ＦｅＣｌ３为混凝剂，ＮａＯＨ为离子沉淀剂和ｐＨ调速剂，采用斜管进行沉降，对废水进行治理。治理后的排放水含Ｚｎ＾２＋为１．０￣１．５ｍｇ／Ｌ，含Ｍｎ＾２＋为１．２￣１．４ｍｇ／Ｌ，含Ｈｇ＾２＋为０．００３￣０．０１０ｍｇ／Ｌ，ｐＨ值为８．５￣８．７，达到广东省广州废水治理排放的ＤＢ４４３     

锂离子电池正极材料LixMn2O4的研究进展

阐述了近年来锂离子电池正极材料LixMn2O4在结构、合成和循环性能的研究情况,归纳了造成容量衰减问题的原因和目前为解决该问题所采用的各种方法.     

基于MAX1873锂电充电控制器的双电源供电系统设计

目前大多数据采集系统采用220V交流电源供电，而在实时性要求高的场合则采用交流电源作为主电源并且蓄电池作为备用电源的双电源系统进行供电，以防止由于交流电源的突然断开而造成数据采集系统的数据丢失。针对220V交流电源供电系统以及交直流双电源供电系统中存在的问题和缺陷，介绍了多节锂电充电控制器MAX1873的特点和充电控制方法，以及利用MAX1873构成的锂电市电双电源供电系统的详细设计方法和设计调试中应注意的问题。     

The dependence of natural graphite anode performance on electrode density

The effect of electrode density for lithium intercalation and irreversible capacity loss on the natural graphite anode in lithium ion batteries was studied by electrochemical methods. Both the first-cycle reversible and irreversible capacities of the natural graphite anode decreased with an increase in the anode density though compression. The reduction in reversible capacity was attributed to a reduction in the chemical diffusion coefficient for lithium through partially agglomerated particles with a larger stress. For the natural graphite in this study the potentials for Li (de)insertion shifted between the first and second formation cycles and the extent of this shift was dependent on electrode density. The relation between this peak shift and the irreversible capacity loss is probably due to the decrease in graphite surface area with compression.