Effect of particle size and purity on the low temperature electrochemical performance of LiFePO4/C cathode material

The reducing particle size of LiFePO4/C material can improve the low temperature performance, and the purity of LiFePO4/C material has more important influence on the low temperature performance. Compared to the high purity LiFePO4/C material, the low purity LiFePO4/C material exhibits poor low temperature performance. At −20 °C under 0.2C, the specific capacity of low purity LiFePO4/C material is 52.4 mAh g−1 lower than that of high purity LiFePO4/C material which is 105.6 mAh g−1. DLi value of low purity LiFePO4/C material is 8.28 × 10−15 cm2 s−1lower two orders than that of high purity LiFePO4/C material which is 2.73 × 10−13 cm2 s−1, leading to the sluggish Li+ ions diffusion kinetics, obtained from the EIS. Therefore, particle size and purity of LiFePO4/C material are the mainly factors influencing the low temperature performance of LiFePO4/C, of which purifying raw material is a deterministic way to improve the low temperature performance of LiFePO4/C material. Low temperature performance curves (a) and Nyquist plots (b) of In-LFP and Re-LFP samples.200