Abstract:

LiFePO4/C composite cathode materials were synthesized by carbothermal reduction (CTR) method using FePO4 as precursor. The precursors and the products were characterized by TG-DTA, FTIR, XRD, and the reaction mechanism was investigated. The compositions and electrochemical performance of the products at different calcination temperatures were studied. The results showed that LiFePO4 in the sample prepared at 300 ℃ was primary phase, so the crystallization temperature in this route was lower than that of other methods. At 300, 400, 500 ℃, Li3PO4 and Fe2O3 as impurity phases existed in the samples and the higher temperature led to less impurity phases. The sample calcined at 600 ℃ had no impurity, but Li4P2O7 appeared at 700 ℃. The sample prepared at 600 ℃ for 24 h had the best electrochemical performance, which could deliver a discharge capacity of 146 mAh·g-1 at 0.1C and retain a discharge capacity of 141 mAh·g-1 after 15 cycles.

Key words: Calcination temperature, LiFePO4, Compositions, Electrochemical performance