How a very trace amount of graphene additive works for constructing an efficient conductive network in LiCoO2-based lithium-ion batteries

Abstract

This work demonstrates how a very low fraction of graphene greatly enhances the usage efficiency of carbon-based conductive additive in LiCoO2-based lithium ion batteries (LIB) and develops a strategy using binary conductive additive to have a high performance battery, especially with excellent rate performance. With a much lower fraction of carbon additive for a commercial LIB, only 0.2 wt% graphene nanosheet (GN) together with 1 wt% Super-P (SP) constructing an effective conductive network, the prepared battery exhibits outstanding cycling stability (146 mAhg−1 at 1C with retention of 96.4% after 50 cycles) and rate capability (116.5 mAhg−1 even at 5C). In this battery, a composite conducting network is formed with a long-range electron pathway formed by a trace amount of GN and the short-range electron pathway by aggregation of SP particles. More interestingly, in micro-sized LiCoO2 system, the GN additive does not present hindrance effect for lithium ion transport even in high rate discharge, which is entirely different from the nano-sized LiFePO4 system. This study further demonstrates commercial potential of GN additive for high performance LIB and more importantly gives a well-designed recipe for its real application.