Synthesis and Evaluation of Olivine Material Coated with Carbon

Abstract

Lithium iron phosphate, LiFePO4, was synthesized by hydrothermal process and subsequently coated with carbon by the thermal decomposition of acetylene gas. The products were characterized by XRD, SEM, and TG-DTA. As-synthesized LiFePO4 was submicron sized plate-like particle. After heating at various temperature in nitrogen atmosphere, the particle size and the crystalline sizes were grown with increasing the heating temperature. Above 700°C, the grain growth was remarkably. Carbon coating temperature was set at 500-600°C because of fine particle and good crystallinity. As a carbon raw material, acetylene gas was flowing to the as-synthesized LiFePO4 in nitrogen atmosphere, and the LiFePO4/C composite was obtained. TG curves showed weight loss above 500°C, which was thought to be associated with carbon layer composition.