Structural and electrochemical characterization of LiFePO_4/C prepared by a sol-gel route with long- and short-chain carbon sources

摘要

A fast and convenient sol-gel route was devel_oped to synthesize LiFePO_4/C composite cathode material, and the sol-gel process can be finished in less than an hour. Polyethyleneglycol (PEG), D-fructose, 1-hexadecanol, and cinnamic acid were firstly introduced to non-aqueous sol_gel system as structure modifiers and carbon sources. The samples were characterized by X-ray powder diffraction, field emission scanning electron microscopy, and elemental analysis measurements. Electrochemical performances of LiFePO_4/C composite cathode materials were characterized by galvanostatic charge/discharge and AC impedance measurements. The material obtained using compound additives of PEG and D-fructose presented good electro_chemical performance with a specific capacity of 157.7 mAh g~(-1) at discharge rate 0.2 C, and the discharge capacity remained about 153.6 mAh g~(-1) after 50 cycles. The results indicated that the improved electrochemical performance originated mainly from the microporous network structure, well crystalline particles, and the increased electronic conductivity by proper carbon coating (3.11%).