Enhancement of electrochemical performance of LiCoO2 cathode material at high cut-off voltage (4.5 V) by partial surface coating with graphene nanosheets

摘要

LiCoO2 cathodes suffer from severe side reactions and rapid capacity fading under high-voltageoperation. In this study, partial coating of LiCoO2 by small size graphene nanosheets was achieved toexperimentally investigate the graphene modification mechanism in improving the electrochemicalperformances of LiCoO2 cathode under 4.5V cut-off voltage. Compared with pristine LiCoO2, G-LCOexhibited better cycling stability and rate capability between 2.5 and 4.5 V vs. Li+/Li. Furtherinvestigation demonstrated that partial coating with graphene nanosheets could effectively suppress theincrease of cell impedance and alleviate the growth of cathode electrolyte interphase(CEI), leading to anoutstanding electrochemical performance. This study gives new insights on enhancing cycling stabilityand rate capability of LiCoO2 under high cut-off voltage.