Effect of Calcination Temperature on the Microstructure and Electrochemical Performance of Nafepo4/C Cathode Materials

Abstract

The NaFePO4/C cathode material containing both amorphous and maricite phases was in-situ constructed through a extremely simple sol-gel method at different calcination temperature without incorporating other complicated technology. The microstructure, phase composition, particle size and distribution, specific surface area of NaFePO4/C were characterized and analyzed by XRD, SEM, TEM, EDS, Raman and BET. Results indicate that with the calcination temperature increasing, the amorphous structure and agglomeration reduce, the crystallinity and particle size increase and the specific surface area increases firstly and then decreases. The electrochemical behavior of cathode materials was analyzed using CV and EIS. The results show that calcination temperature influences the charge-discharge specific capability, Na+ diffusion coefficient and charge transfer resistance of NaFePO4 cathode materials, and it has the best electrochemical performance at 450 oC, the dicharge specific capability is 106.7 mAh·g−1, Na+ diffusion coefficient is 1.026×10-17 cm2 s-1 and charge transfer resistance is 998.6 Ω.

Keywords: Sodium iron phosphate, Calcination temperature, Microstructure, Electrochemical performance