Lithium deintercalation/intercalation processes in cathode materials based on lithium iron phosphate with the olivine structure

Abstract

This review describes the current state of the studies of lithium deintercalation/intercalation processes in cathode materials based on lithium iron phosphate with olivine structure. The limiting factors of LiFePO4 charge/discharge processes, as well as the main methods for their acceleration are considered. A partial replacement of iron cations in the structure improves the electrochemical characteristics of the cathode materials, including the discharge capacity, charge/discharge rate, and, in some cases, changes the charge/discharge mechanism. The use of nanoscale phosphate LiFePO4 with the olivine structure considerably increases the charge/discharge rate of cathode materials based on it by reducing the diffusion path length. Methods for LiFePO4 surface modification are considered. Particular attention is paid to the development of composite materials with electron-conducting additives. Combining of various approaches to the modification of the material in question makes it possible to obtain materials with a discharge capacity close to the theoretical value (170 mA h g–1) at a low charge/discharge rate and to considerably increase its capacity at high charge and discharge currents.