Synthesis of nanoscale LiCoPO4/C between few-layer graphene and its influence on electrochemical performance for lithium-ion batteries

Abstract

In this study, the composite cathode material of LiCoPO4/C and graphene is synthesized using solvothermal method assisted by oleylamine. The effect of graphene addition on the material properties is fully investigated, and the synergistic effect of amorphous carbon and graphene is also studied. Graphene serves as a conductive skeleton and provides abundant diffusion paths for electrons. The nanoscale LiCoPO4 material synthesized by solvothermal method is evenly distributed around the few-layer graphene with the assistance of oleylamine, and the amorphous carbon formed after the pyrolysis of oleylamine at high temperature tightly connects LiCoPO4 to the graphene, which improves the conductivity and electrochemical performance of the sample. The results of characterization reveal that adding graphene can prepare LiCoPO4 materials with good crystallization and improve the specific surface area and pore size of the material. At the same time, the amorphous carbon and graphene inside the material also show a good degree of graphitization. Electrochemical test results show that doping graphene with a mass ratio of 6% can enhance the electrochemical performance and cycle stability of LCPC-6%G sample. The initial discharge capacity of LCPC-6%G sample reaches 157.2 mA h g−1 at 0.1 C. In this study, nanoscale LiCoPO4 samples are successfully synthesized on the surface of graphene, which provides a new idea for the preparation of nanoelectrode materials and conductive skeleton composite samples.