Abstract:

Cathode material LiFePO4 /C was successfully prepared via the spray drying-carbothermal reduction method,with inexpensive ferric iron ( Fe³⁺ ) as the iron source and with polyethylene glycol ( PEG) as the assisted template and the carbon source. Then,the microstructure of the material was characterized,and the effects of PEG dosage and calcination temperature on the structure and performance of the material were investigated. The results show that the product possesses mesoporous structure,beautiful hierarchical spherical morphology,high specific surface area,high capacity and excellent cyclic stability,that too low PEG dosage may result in incomplete reduction of Fe³⁺,while excessive PEG may hinder the Li ⁺ diffusion because the carbon layer is too thick,that the optimum PEG dosage is about 150 g /mol,that appropriate calcination temperature may result in high conductivity because it decreased the disordered /graphene ( D/G) proportion of the residual carbon,that the optimum calcination temperature is about 750℃,and that the material prepared under the optimal conditions,whose initial discharge capacities at the rates of 0. 1,0. 5,1. 0,2. 0 and 5. 0C are respectively 149. 2,139. 0,116. 8,102. 4 and 82. 1mAh/g,is of good rate-cyclic stability.

Key words: polyethylene glycol, spray drying, carbothermal reduction method, LiFePO4 /C, cathode material, mesoporous structure