Low Temperature Synthesis and Characterization of Carbon-Coated LiMnPO4 for Lithium-Ion Batteries

Abstract

LiMnPO4 based phospho olivines are considered to be environmentally friendly, and low cost potential cathode material for the next generation of Li-ion secondary batteries to meet the huge market of electric and hybrid vehicles [1, 2]. The relatively higher operation voltage at around 4 V makes the theoretical specific energy of LiMnPO4 (684 Wh/kg) 20% greater than that of LiFePO4 (578 Wh/kg) while still compatible with most conventional electrolytes [3]. However, due to the low electrical conductivity and poor Li ion diffusion kinetics these materials are unsuitable for practical applications [4]. In here, carbon coated LiMnPO4 was synthesized by both solid state and modified sol-gel technique using a low temperature synthesis techniques. The cathode materials obtained were characterized and performance was compared and evaluated. Results of the electrochemical tests show that the prepared LiMnPO4/C (around 10 wt. % carbon) composites by both the routes exhibits not only a high initial discharge capacity but also good cycling stability. Although highly crystalline phase pure cathode materials could be obtained by both the processes, the materials prepared by sol-gel process delivered slightly better electrochemical performance when compared to solid state process.