Y3+ doping and electrochemical properties of LiFe0.5Mn0.5PO4@C cathode material for lithium-ion batteries

LiFe0.5Mn0.5−xYxPO4@C (x = 0, 0.005, 0.01, 0.02, and 0.03) cathode materials were synthesized by a carbothermal solid-state reaction method, and the microstructure and the surface morphology were investigated by XRD, XPS, TEM and SEM technologies. The results show that Y3+ ions are successfully doped into the olivine structure, leading to cell volume shrinkage and an amorphous carbon coating on the particle surface, while the size and dispersion of the particles are also improved. The electrochemical properties of the preferred LiFe0.5Mn0.49Y0.01PO4@C sample were measured by galvanostatic charge-discharge, CV, EIS and GITT methods. The results show that Y3+ doping can significantly decrease its potential polarization, promotes the reduction kinetics of Mn3+ ions and effectively enhances the Li+ diffusion coefficient at 4.1 V. It can provide a discharge specific capacity of 160 mAh g−1 at 0.1 C with an initial coulombic efficiency of 90.1%, 122.93 mAh g−1 at 1 C with a capacity retention of 87.74% after 300 cycles, and 44.89 mAh g−1 at 10 C.