▎ 摘　　要

Graphene and derivatives have been considered as useful additives to improve the electrochemical property of the cathodes in lithium ion batteries. To get insight into the effects of graphene sheets on the electrochemical properties of LiCoO2, in the work, LiCoO2 coated with graphene sheets with micrometer sized lateral sizes, porous graphene sheets, and graphene quantum dots are prepared, and their electrochemical properties are studied systematically. It is demonstrated that the capacity, rate capability and charge/discharge cycling stability of LiCoO(2 )can be improved, but depends on the lateral size and the basal plane morphology of the graphene sheets. In contrast, the graphene sheets with lateral sizes in micrometer can more efficiently improve the overall electrochemical performances. (C) 2019 Elsevier B.V. All rights reserved.