Improvement of electrochemical properties of lithium iron phosphate cathode by rare earth oxides modification

Abstract

LiFePO4 cathode material has sluggish Li-ion diffusivity, which largely depends on surface modification to accelerate its slow kinetic process. Metal oxides, such as Al2O3, are promising coating materials to improve the capacity retention of the cathode materials in lithium-ion batteries, but their improvement on the diffusion rate of Li-ion is limited. In order to obtain the lithium iron phosphate cathode material with excellent rate and cyclic stability, this paper uses the advantages of La2O3 which has both good stability and low lithium ion diffusion barrier to prepare LiFePO4/C@La2O3 by a simple and easy operation method. The cathode of LiFePO4/C@La2O3 shows high lithium ion diffusivity of 1.4982 × 10−13 and decreased interface impedance by calculating the Li+ diffusion coefficient and measuring conductivity. Furthermore, the LiFePO4/C@La2O3 exhibits excellent rate capacibility (126 mAh g−1 at 10 C within 2.4–4.2 V) and long-cycle stability (96.5% capacity retention at 1 C after 500 cycles). These results indicate that further research on these oxide coating materials can enlarge the applicability of these materials.