Mechanism studies and electrochemical performance optimization on xLiFePO4•(1-x)Li3V2(PO4)3 hybrid materials

Hybrid materials xLiFePO(4)center dot(1 -aEuro parts per thousand x)Li3V2(PO4)(3) were synthesized by sol-gel method, with phenolic resin as carbon source and chelating agent, methylglycol as surfactant. The crystal structure, morphology and electrochemical performance of the prepared samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), galvanostatic charge-discharge test and particle size analysis. The results show that LiFePO4 and Li3V2(PO4)(3) co-exist in hybrid materials, but react in single phase. Compared with individual LiFePO4 and Li3V2(PO4)(3) samples, hybrid materials have smaller particle size and more uniform grain distribution. This structure can facilitate Li ions extraction and insertion, which greatly improves the electrochemical properties. The sample 0.7LiFePO(4)center dot 0.3Li(3)V(2)(PO4)(3) retains the advantages of LiFePO4 and Li3V2(PO4)(3), obtaining an initial discharge capacity of 166 mA h/g at 0.1 C rate and 109 mA h/g at 20 C rate, with a capacity retention rate of 73.3% and an excellent cycle stability.