Study on the impact of Fe 2 P phase on the electrochemical performance of LiFePO 4

Abstract The research on impurity in the lithium iron phosphate has been a hot topic. Especially when prepared by the solid state method, the impurities occurred easily through high-heat sintering. But some impurity is not completely bad for the cell performance, such as Fe 2 P. In this paper, the influence of Fe 2 P has been researched. Using the magnetic separation method, the high and low contents of Fe 2 P in lithium iron phosphate are obtained and then compared with the primary sample. Results show that the Fe 2 P phase helps to improve the rate and cycling performances, but a too high content will decrease the specific capacity of the sample due to the low content of active material. It is proven with the electrochemical measurement that the Fe 2 P phase could enhance the electrical conductivity of cathode, but it gives electrochemical inactivity. It can be concluded that the high rate or high capacity types LiFePO 4 could be obtained by controlling the content of Fe 2 P through adjusting the preparation process.