Study on the impact of Fe2P phase on the electrochemical performance of LiFePO4

Abstract

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 Fe2P. In this paper, the influence of Fe2P has been researched. Using the magnetic separation method, the high and low contents of Fe2P in lithium iron phosphate are obtained and then compared with the primary sample. Results show that the Fe2P 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 Fe2P 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 LiFePO4 could be obtained by controlling the content of Fe2P through adjusting the preparation process.