Enhancement of electrochemical performance of LiCoO2 cathode material at high cut-off voltage (4.5 V) by partial surface coating with graphene nanosheets
Jixian Wang, Nan Wang, Wenzheng Nan, Chen Wang, Xiang Chen, Xin Qi, Shaojiu Yan, Shenglong Dai
Abstract
LiCoO 2 cathodes suffer from severe side reactions and rapid capacity fading under high-voltage operation. In this study, partial coating of LiCoO 2 by small size graphene nanosheets was achieved to experimentally investigate the graphene modification mechanism in improving the electrochemical performances of LiCoO 2 cathode under 4.5V cut-off voltage. Compared with pristine LiCoO 2 , G-LCO exhibited better cycling stability and rate capability between 2.5 and 4.5 V vs. Li + /Li. Further investigation demonstrated that partial coating with graphene nanosheets could effectively suppress the increase of cell impedance and alleviate the growth of cathode electrolyte interphase(CEI), leading to an outstanding electrochemical performance. This study gives new insights on enhancing cycling stability and rate capability of LiCoO 2 under high cut-off voltage.