Preparation and electrochemical characterization of LiFePO4 nanoparticles with high rate capability by a sol–gel method

The synthesis of LiFePO4 nanoparticles by an adipic acid-assisted sol–gel route has been optimized based on cycling and structural analysis. Formation of the crystalline phase was investigated through thermogravimetric-differential thermal analysis (TG-DTA). Among the optimized conditions, a 0.5 molar ratio of the adipic acid to total metal ions at a 670 °C calcination temperature under an Ar atmosphere yielded LiFePO4 particles with the desired properties. The synthesized particle sizes ranged from 50 to 100 nm. The Li/LiFePO4 cell exhibited an initial discharge capacity of 150 mAh g−1 that was maintained for 100 cycles. Elevated temperature (50 °C) performance of the cell is also described, showing a stable discharge behavior up to 60 cycles without any decline in capacity. Furthermore, the cell was subjected to rate capability studies (1–30 C) that suggested excellent capacity retention of the cell at ambient temperature. We conclude that the adipic acid-assisted sol–gel process is an excellent route to product LiFePO4 powders on large scale with high rate capability and retention.