Improved Cycle Stability and Rate Capability of Graphene Oxide Wrapped Tavorite LiFeSO4F as Cathode Material for Lithium-Ion Batteries

摘要

Tavorite LiFeSO4F has been regarded as a promising alternative to LiFePO4 due to its high Li ionic conductivity. To overcome the low electronic conductivity of LiFeSO4F, we prepared a graphene oxide (GO)/LiFeSO4F composite material by the solvothermal method. The GO wraps on the surface of LiFeSO4F and links the adjacent particles, thus providing an effective network for electrons transport. As a result, the electronic conductivity of the material is improved from 8.16 x 10(-11) S cm(-1) to 1.65 x 10(-4) S cm(-1). In addition, the GO depresses the side reactions of the electrode and electrolyte, promotes the charge transfer reactions at the electrode/electrolyte interface, and facilitates the lithium diffusion in the electrode. The GO-wrapped LiFeSO4F exhibits much better electrochemical performance than the pristine material. It showed a discharge capacity of 113.2 mAh g(-1) at the 0.1 C rate with 99% capacity retention after 100 cycles. In addition, the material is able to deliver 85.1, 73.4, and 30.3 mAh g-1 at high current rates of 1 C, 2 C, and 10 C, respectively.