LiFePO4/C cathode material prepared with a spherical, porous, hollow Fe-3(PO4)(2)/C composite as a precursor for lithium-ion batteries

摘要

Spherical porous hollow Fe-3(PO4)(2)/C composites with graftonite crystals were prepared in a mixed solvent of water and ethylene glycol by the solvothermal method. Then, olivine-structured LiFePO4/C was successfully synthesized by a solid phase reaction using Fe-3(PO4)(2)/C as the precursor mixed with nanospherical Li3PO4. The experimental results show that different proportions of mixed solvents have important effects on the morphology and carbon content of Fe-3(PO4)(2)/C, which further influence the electrochemical properties of LiFePO4/C. Compared with LiFePO4/C prepared with FePO4 as the precursor, LiFePO4/C prepared using Fe-3(PO4)(2)/C with a water/ethylene glycol ratio of 1:1 as the precursor shows a better electrochemical performance with a discharge capacity of 165 mAh/g and a capacity retention rate of 96% over 100 cycles at 0.5 C. Using porous hollow Fe-3(PO4)(2)/C as the precursor for preparing LiFePO4/C is beneficial to the lithium-ion escaping and embedding during the process of charging and discharging, enhancing the discharge capacity and cycle stability of the cathode material.