Effect of carbon source on electrochemical performance of carbon coated LiMnPO₄ cathode

Abstract

Source materials for carbon coating on LiMnPO₄ were examined to improve an electrochemical performance of LiMnPO₄. L-ascorbic acid, sucrose, polyethylene oxide (PEO), and carboxymethyl cellulose (CMC) were used as carbon sources for hydrothermal synthesis of carbon coated LiMnPO₄. Disordered (D) and graphite-like (G) carbons were detected by Raman spectroscopy for the prepared samples except for PEO-used one, and the highest G/D ratio was obtained for the sample prepared using CMC as carbon source. The electrochemical performance of the samples was evaluated by galvanostatic charge/discharge test. The carbon coated LiMnPO₄ prepared with CMC carbon source showed the highest discharge capacity, 94 mA h g^-1 at 0.01 C (corresponding to 55% of the theoretical capacity, 171 mA h g^-1), indicating that the carbon sources greatly influenced on the electrochemical performance of the carbon coated LiMnPO₄ prepared by the hydrothermal synthesis.