Effects of graphene with different sizes as conductive additives on the electrochemical performance of a LiFePO4 cathode

Abstract

This paper aims to demonstrate whether graphene nanosheets (GN) with different sizes as conductive additives are able to affect the electrochemical performance of a LiFePO₄ (LFP) cathode. The results of electrochemical measurements present that graphene nanosheets (GN) and Super-P (SP) used as conductive additives simultaneously could construct an effective electronic conducting network and achieve excellent electrochemical performance when compared with traditional carbon materials. A LFP with small-size GN shows better specific capacity and rate performance than those with medium-size and large-size GN, and the LFP with large-size GN displays a poor rate performance. The results indicate that the specific capacity and rate performance tend to worsen with the increase of the size of graphene, owing to the length of the lithium ion transport path being prolonged and the ionic conductivity decreasing greatly by the “barrier effect” of graphene.