富锂锰基层状氧化物正极材料电压衰减的研究

Study on Voltage Decay of Lithium-rich Mn-based Layered Oxides Materials

富锂锰基层状氧化物正极材料具有容量高、理论能量密度高和价格低等优点引起了研究者关注,有望成为下一代高比能量电池的优选材料.但该材料循环过程中存在严重的电压和容量衰减问题,限制其商业应用.本文首先总结了引起电压和容量衰减的主要原因:(1)材料自身结构的转化;(2)金属阳离子的不可逆迁移;(3)循环过程中产生电压滞后现象;(4)循环后形成SEI膜.其次归纳了3条有效改进措施:表面包覆、离子掺杂和改进电解液添加剂.最后基于作者的实验结果对该材料的发展进行展望,指出注重电池中各组成部分的协同作用有利于加快富锂锰基正极材料的商业化使用.

Lithium-rich Mn-based layered oxides(LLOs)have attracted attention due to their high capacity,high theoretical energy density and a lower cost,which is expected to be the preferred material of high specific energy batteries for the next generation.Unfortunately,they show severe voltage and capacity decay,which hindered the commercial applications of LLOs materials.In this paper,first,the causes of voltage and capacity decay of LLOs materials during the cycle are as follows:(1)transformation of material's structure;(2)irreversible migration of metal cation;(3)voltage hysteresis occurred in the circulation process;(4)SEI film formation after cycling.Second,corresponding three effective improvement measures are summarized,including surface coating,ions doping and improved electrolyte additive.Finally,based on the author's experimental results,the future development of LLOs materials is prospected,the synergistic effect of the components in the battery is beneficial to accelerating the commercial use of LLOs cathode material.