Synthesis and characterization of LiFePO4 electrode materials coated by graphene

Olivine-type LiFePO4/graphene composite materials were synthesized via a high temperature solid-state method. In this paper, the sintering process of LiFePO4 precursor was conducted simultaneously with the reduction of graphene oxide, and then LiFePO4 with a thin and homogeneous graphene-shell coating can be obtained. The effects of different graphene coating amount on the structure and electrochemical properties of LiFePO4 cathode were investigated. Test results indicated that LiFePO4 material modified with high electrical conductive graphene exhibited a morphology of uniform and fine spherical particles with high crystallinity. LiFePO4/graphene (92:8 wt.) cathode had the lowest charge transfer resistance among all tested samples. It delivered a capacity of 167 mAh g−1 at 0.1 C and could tolerate various discharge currents with a capacity decay rate of only 27.2% after cycled stepwise under 0.1 C, 2 C, 5 C for 15 times, respectively.