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 degrees C calcination temperature under an At 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 mAhg(-1) that was maintained for 100 cycles. Elevated temperature (50 degrees 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 (1-30C) 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. (C) 2009 Elsevier B.V. All rights reserved.