Search

Commercialized lithium iron phosphate (LiFePO4) batteries have become mainstream energy storage batteries due to their incomparable advantages in safety, stability, and low cost. However, LiFePO4 (LFP) batteries still have the problems of capacity decline, poor low-temperature performance, etc. The problems are mainly caused by the following reasons: (1) the irreversible phase transition of LiFePO4; (2) the formation of the cathode–electrolyte interface (CEI) layer; (3) the dissolution of the iron elements; (4) the oxidative decomposition of the electrolyte; (5) the repeated growth and thickening of the solid–electrolyte interface (SEI) film on the anode electrode; (6) the structural deterioration of graphite anodes; (7) the growth of lithium dendrites. In order to eliminate the problems, methods such as the modification, doping, and coating of cathode materials, electrolyte design, and anode coating have been studied to effectively improve the electrochemical performance of LFP batteries. This review briefly describes the working principle of the LFP battery, the crystal structure of the LFP cathode material, and its electrochemical performance as a cathode. The performance degradation mechanism of LFP batteries is summarized in three aspects—cathode material, anode material, and electrolyte—and the research status of LFP material modification and electrolyte design is emphatically discussed. Finally, the challenges and future development of LFP batteries are prospected. [ABSTRACT FROM AUTHOR]

The spherical Li-rich materials 0.3Li2MnO3·0.7LiNi0.5Mn0.5O2 are synthesized by a standard co-precipitation method followed by solid state sintering. The primary particle size and morphologies of the 0.3Li2MnO3·0.7LiNi0.5Mn0.5O2 materials can be readily controlled by altering the heat-treatment temperature. With different primary size, the materials show different rate discharge capabilities. However, due to similar chemical composition, they show similar discharge capacity at high temperature and low current density. Subsequent galvanostatic intermittent titration tests indicate that the larger the particle size, the larger the chemical diffusion coefficient of the Li+. The relationship between the primary particle size and electrochemical kinetics is discussed. Of all the samples in this study, the material with a primary particle size of 200 nm, obtained at 900 °C, exhibits the best integrated electrochemical performance. [ABSTRACT FROM AUTHOR]