锂离子电池高电压正极材料表面钝化膜的调控和性能研究

项目名称： 锂离子电池高电压正极材料表面钝化膜的调控和性能研究

项目编号： No.21473241

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 吴晓东

作者单位： 中国科学院苏州纳米技术与纳米仿生研究所

项目金额： 80万元

中文摘要： 提高正极材料的工作电压，是锂离子电池的能量密度进一步提高的必由之路，但是当工作电压高于电解液稳定的电化学窗口时，电解液会在正极材料表面发生氧化分解反应，造成电解液的消耗，导致电池寿命缩短，搁置性能降低，并且电解液分解产生气体会造成电池胀气，可能产生危险。为了解决这一问题，必须在高电压工作的正极材料表面形成一层稳定的具有电子绝缘、锂离子导通、结构致密、与电极接触良好、在电解液中溶解度低的表面钝化膜。但是，研究发现，正极材料表面的钝化膜往往十分薄，而且在高电压下不稳定，容易造成电解液的持续消耗。为此，本项目针对在高电压正极材料表面形成稳定有效的钝化膜这一目标，通过制备薄膜电极与微晶电极，结合多种检测技术，研究电解液组分在高电压正极材料表面的反应过程，并通过理论计算与实验筛选，优化电解液配方与添加剂种类，将其应用于实体高电压锂离子电池，提高锂离子电池的能量密度、循环寿命、安全性以及搁置性。

中文关键词： 电解液添加剂；高电压正极材料；钝化膜；锂离子电池；表面与界面

英文摘要： Increasing the working voltage of cathode materials is the way which must be passed to enhance the energy density of lithium-ion batteries. However, when the working voltage is higher than the stable window of electrolyte, electrolyte will oxygenolysis on the surface of cathode materials. This will consume electrolyte, shorten lifetime and shelf-life of battery, and the decomposition of electrolyte will lead to the gas and bloating of battery. In order to solve this problem, a surface passive film with electron insulation, lithium ions conduction, compact, contact well to electrode, and low solubilty in electrolyte must be formed between the cathode materials and electrolyte. It was found that the passive films on cathodes are often to be thin, and unstable under high voltage, which will lead to the contunous consumption of electrolyte. So, in thie project, we are focusing on forming stable and effective passive films on high voltage cathode materials.We will prepare thin film electrodes and microcrystal electrodes, combining with multiple investigating techniques, to study the reaction processes of electrolyte on th surface of cathode materials. We will optimize the electrolyte recipes and additives by theoretical calculation and experimental screening, and apply these electrolyes and additives in the high voltage lithium-ions battery, to enhance the energy density, cycle life, shelf-life and safety.

英文关键词： electrolyte additive;high voltage cathode material;passive film;lithium-ion battery;surface and interface