尖晶石型LiMn2O4高温失效机制及解决方法

尖晶石型LiMn2O4在高温下的容量衰减是阻止其商品化的重要原因.国内外研究结果表明,导致高温下电化学性能失效的原因是多方面的.电解液中微量水的存在会导致LiPF6的分解而产生HF,由此造成Mn溶解.碳阳极表面形成的SEI钝化层会导致锂离子蓄电池体系中锂的损失.此外Jahn-Teller效应和高温下LiMn2O4结构的变化也会导致LiMn2O4高温容量损失.通过对高温失效机制的分析,提出了通过减小尖晶石比表面积、表面修饰改性来减小电解液的分解、在电解液中添加合适添加剂来中和HF、通过阴阳离子掺杂来稳定尖晶石的结构和阻止Jahn-Teller效应的方法来改善尖晶石高温性能的方法.

Mechanism and solution for the failure of spinel LiMn2O4 at high temperature

The capacity fading of spinel LiMn 2O 4 at high temperature is an important factor that affects its commercialization. The mechanisms of electrochemical property failure of LiMn 2O 4 at high temperature are described as the follows. Mn is dissolved due to the production of HF produced by the decomposition of LiPF 6, which is caused by trace water in electrolyte. Lithium in Li ion battery system is lost because the SEI passive layer is formed onto the surface of carbon anode. In addition, the capacity fading of LiMn 2O 4 at high temperature is caused by the Jahn Teller effect and the change of LiMn 2O 4 structure at high temperature. The solutions to improve the property of spinel LiMn 2O 4 at high temperature, such as decreasing electrolyte decomposition by surface modification and reducing the specific surface area of spinel, neutralizing HF by adding proper additives into electrolyte, stabilizing the spinel structure and inhibiting the Jahn Teller effect by doping anion and cation, etc, by means of the analysis of failure mechanism are presented.