Optimized synthesis of nano-sized LiFePO4/C particles with excellent rate capability for lithium ion batteries

Olivine-type LiFePO4/C composite with excellent rate capability and cycling stability is synthesized by an optimized ethylene glycol assisted solution-phase method. In an attempt to improve the electrochemical performance, the size of LiFePO4/C particle is reduced by optimizing the reaction time and temperature. The results show that the LiFePO4/C synthesized at 130 °C for 5 h consists of well-distributed nano-particles of size about 50 nm in diameter and 100 nm in length, which is uniformly coated with a carbon layer about 3.0 nm in thickness. The material synthesized at 130 °C exhibits the least charge-transfer resistance than the LiFePO4/C synthesized at 120 and 140 °C. The specific capacity of optimized LiFePO4/C at discharge rate of 0.1 C can reach to 166.5 mAhg−1, nearly to the theoretical capacity. Even at high rate of 5, 10, 20 and 30 C, the specific capacities of 132.3, 120.4, 97.3 and 66.6 mAhg−1 are achieved, respectively, with no significant capacity fading after 100 cycles. This is a promising method used in industrialization to synthesize LiFePO4/C composite with excellent performance.