Impact of evolution of cathode electrolyte interface of Li(Ni0.8Co0.1Mn0.1)O2 on electrochemical performance during high voltage cycling process  

作　　者：Wei Wang Qin Yang Kun Qian Baohua Li 

机构地区：[1]Engineering Laboratory for Next Generation Power and Energy Storage Batteries,Graduate School at Shenzhen,Tsinghua University,Shenzhen 518055,Guangdong,China [2]School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China

出　　处：《Journal of Energy Chemistry》2020年第8期72-78,I0003,共8页能源化学（英文版）

基　　金：supported by the National Key Basic Research Program of China (No.2014CB932400);Joint Fund of the National Natural Science Foundation of China (No.U1401243);National Natural Science Foundation of China (No.51232005);Shenzhen Technical Plan Project (No.JCYJ20150529164918735,CYJ20170412170911187,KQJSCX20160226191136);Guangdong Technical Plan Project (No.2015TX01N011)。

摘　　要：In this work, the electrochemical performance of LiNi0.8Co0.1Mn0.1O2(NCM811) has been investigated after cycling with various upper cutoff voltages. Noteworthily, electrochemical impedance of NCM811 declined with the increasing cycle number to high voltages. It was found that the decline of charge transfer impedance could be related to the structural and compositional change of cathode electrolyte interphase(CEI) of NCM811 when charging to high voltages, based on the characterization of electrochemical impedance spectroscopy(EIS), X-ray photoelectron spectroscopy(XPS) and transmission electron microscopy(TEM). The corresponding mechanism has also been proposed in this study. Specifically, due to the increasing roughness of cathode surface, the bottom of CEI film and cubic phase on cathode surface form a transition region mainly at high voltages, leading to the nonobvious boundary. This newly formed transition region at high voltages could promote the Li ion diffusion from electrolyte to cathode, then reducing charge transfer impedance. Additionally, the decrease of Li F on the surface of the cathode could also make a contribution to lower the interface impedance. This study delivers a different evolution of CEI on NCM811, and the impact of CEI evolution on electrochemical performance when charging to a high voltage.

关 键 词：Cathode electrolyte interface NCM811 OVERCHARGE Rock salt phase 

分 类 号：TM912[电气工程—电力电子与电力传动] O614.111[理学—无机化学]