Optimized synthesis of nano-sized LiFePO₄/C particles with excellent rate capability for lithium ion batteries
By Liu, Houbin; Miao, Cui; Meng, Yan; He, Yan-Bing; Xu, Qiang; Zhang, Xinhe & Tang, Zhiyuan
Published in Electrochimica Acta
2014
Abstract
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.