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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]

A simple method was applied to control the morphology of LiMn2O4 and Li1.05Mn1.97Nb0.03O4 in the sintering process by premixing a suitable proportion of acetylene black in the raw material. Both specific discharge capacity and cycling stability of the samples were improved. The results demonstrated that the doped samples showed excellent electrochemical performance at both 25 °C and 55 °C. [ABSTRACT FROM AUTHOR]

A Ni/Mn composite precursor was prepared as the precursor for Li-rich cathode materials under an air-precipitation atmosphere in a continuous stirred-tank reactor (CSTR). The nucleation and growth of precursor particles were investigated during the CSTR process by monitoring particle morphology, chemical composition, and phase composition. It was found that the particle shape and chemical composition were not homogeneous in the early stages of co-precipitation and did not become so until after 4 h. Mn ion oxidation was verified to occur during the entire course of precipitation by X-ray diffraction. The final precipitate was identified as a two-phase system consisting of a Ni/Mn layered double hydroxide phase and a MnO phase. Scanning electron microscopy and an N adsorption-desorption test revealed the porosity and surface area of the material. A Li-rich cathode material was synthesized using the final precipitate as a precursor; the electrochemical performance of this cathode material is reported in this article. [ABSTRACT FROM AUTHOR]

Li 1.1Mn 2 − 2xCo xNi xO 4 ( x = 0, 0.075) spinel powders were successfully synthesized using a liquid stirred tank reactor method. The electrochemical performances of the undoped and doped spinels at 4.3 and 5 V were investigated by X-ray diffraction, field-emission scanning electron microscopy, and electrochemical impedance spectroscopy. The capacity of Li 1.1Mn 2 − 2xCo xNi xO 4 could be divided into two parts, with 4.3 V as the dividing line in the 3–5 V charge–discharge range. Low capacity and good cyclic performance were obtained when cycled in the 3–4.3 V range for the multi-doped Li 1.1Mn 2 − 2xCo xNi xO 4 spinel. In comparison with multi-doped spinel at 4.3 V, the results of the cyclic performance worsened at 5 V because the structure underwent further shrinkage, the charge transfer resistance rose and the electrolyte decomposed. [ABSTRACT FROM AUTHOR]