Control and influence of morphology, particle size and structure of LiFePO4 on its properties

The problems of enhancing tap density and electrochemical performance of LiFePO4/C were studied when FePO4 was prepared by in-situ polymerization-precipitation method and LiFePO4/C was prepared by carbothermal reduction method. The morphology of LiFePO4/C can be controlled by adjusting the preparation conditions of precursor FePO4. Spherical morphology of particles is beneficial to improve the tap density and high rate performance of LiFePO4/C. Although the high compactness of LiFePO4 particles results in high tap density, high compactness of particles is not conducive to improving the electrochemical performance of the materials. Therefore, when improving the compactness of materials to increase their tap density, it is necessary to consider their negative impact on electrochemical performance. The influence of filling effects between different particles on improving the tap density was studied. With LiFePO4/C prepared by in-situ polymeration-coprecipitation method as the first principal particle size, and LiFePO4/C prepared by in-situ polymeration-hydrothermal method as the second principal particle size, when particle size and mass ratios conform to Hudon and Horsfield filling theory, small particles can fill the void formed by the accumulation of large particles. The tap density of LiFePO4 is 1.3649 g cm−3, and the specific capacity is 94.85 mA h g−1 at 5C.