Synthesis, characterization and electrochemical performances of MoO2 and carbon co-coated LiFePO4 cathode materials

Abstract

The MoO2 and carbon co-coated LiFePO4 cathode materials were synthesized by a combined technique of solid state synthesis and the sol–gel method. Phase compositions and microstructures of the products were characterized by X-ray powder diffraction (XRD), Raman, SEM and TEM. Results indicate that MoO2 can sufficiently coat on the LiFePO4 surface and does not alter LiFePO4 crystal structure, and the existence of MoO2 increases the graphitization degree of carbon. SEM and TEM images reveal that MoO2 presence has little impact on LiFePO4 particle size. The electrochemical behavior of cathode materials was analyzed using galvanostatic measurement and cyclic voltammetry (CV). The results show that the existence of MoO2 improves electrochemical performance of LiFePO4 cathode material in specific capability and low-temperature behavior. The apparent lithium ion diffusion coefficient increases with MoO2 content and maximizes around the MoO2 content of x=5wt%. It has been had further proved that the higher electronic conductivity of MoO2 and carbon enhances the lithium ion transport to improve the electrochemical performance of LiFePO4 cathode materials.