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.