Li_2MnO_3的电化学活性及脱嵌锂机理研究进展

Electrochemical Activity and Mechanism of Disengagement of Lithium for Li_2MnO_3

富锂固溶体正极材料xLi2MnO3.(1-x)LiMO2(M=Co,Ni,Mn…),首次不可逆容量很大程度上与组分中的Li2MnO3电化学过程有关。富锂固溶体正极材料4.5V区域充电平台是组分中Li2MnO3电化学活化过程;Li2MnO3首次循环不可逆容量较大,约在50～100mAhg-1,4.5V电位脱出Li+同时脱出O2-,等效脱出不可嵌入的Li2O;Li2MnO3与分解的电解液发生离子交互反应后,H+占据不可逆位置,阻碍了Li+的嵌入;多周循环晶体结构改变,形成不可逆结构并有新相生成。本文综合介绍近几年关于Li2MnO3结构、常温脱嵌锂机理、高温下电解液分解及循环后结构变化等方面的研究现状。

The initial irreversible capacity of Lithium-rich solid solution cathode materials xLi2 MnO3 . （1-x）LiMO2 （M=Co,Ni,Mn…） is largely decided by the electrochemical process of Li2 MnO3 in the components. It is the re gional platform at 4.5 V of the lithium rich solid solution cathode materials that is the electrochemical active process of Li2 MnO3. The first cycle irreversible capacity of Li2 MnO3 is about 50- 100 mAhg-1 , disengaging of Li. and O2- in the same amount of Li20 at 4.5V potential at the same time. After the ion exchanges react with the decomposi- tion of electrolyte,it blockes the intercalation of Li＋ and H＋ occupies the irreversible position. The crystal structure changes after several cycles and new phase has generate. This paper mainly introduces the research status at recently years of the structure and preparation of Li2 MnO3, the mechanism of the disengagement of lithium, the electrolyte decomposition at high temperature and the crystal structure changes after several cycles.