Study On The Preparation Of Lithium Iron Phosphate Cathode Material

Lithium iron phosphate is a good cathode material for its safety and good specific capacity. In this study LiFePO4/C was prepared via co-precipitation method using LiOH, FeSO4and H3PO4as raw materials. Firstly, reaction conditions of preparing LiFePO4/C in mixing reactor were investigated, on this basis optimal conditions of preparation in rotor-stator reactor were determined and LiFePO4/C powders was characterized by XRD, TEM and electrochemical performance test.(1) Impact of different mole ratio and mixing ways of raw material, reaction temperature, calcination temperature and duration to LiFePO4/C prepared in mixing reactor were researched and obtained the optimal condition, i.e. mole ratio of Li:Fe:P was3:1:1, LiOH solution was added to the mixed solution of FeSO4and H3PO4, reaction temperature was50℃, calcinated in700℃for8h. LiFePO4/C powders’size was0.5-1.5μm, at0.1C rate, specific capacity was105.1mAh/g, after20cycles, retention rate was99.8%.(2) LiOH solution and mixing solution of FeSO4and H3PO4were mixing in rotor-stator reactor. Impact of mole ratio of raw material, different rotation speed, flow and concentration of LiOH solution to LiFePO4/C prepared in rotor-stator reactor were researched and obtained the optimal condition, i.e. rotation speed was mole ratio of Li:Fe:P was3:0.8:1,2000rpm, flow of LiOH solution was8mL/min, concentration was0.8M. In optimal conditions, LiFePO4/C powders’size was around400nm,0.1C rate specific capacity was142mAh/g, after25cycles, capacity was141.5mAh/g, retention rate was99.6%.