High Power LiMnPO₄Cathode Coated with Hybrid Layer of Li Ion-Conductive Phosphate and Electro-Conductive Carbon

Abstract

The enhancement in rate performance of LiMnPO4 cathode material for Li ion batteries has not been established for practical high power use, mainly because of its extremely poor electron and Li ion conductivities. In order to overcome this problem, we have developed a novel hybrid-coated LiMnPO4, where very thin amorphous hybrid-coated layers of Li ion-conductive phosphate with electro-conductive pyrolytic carbon are formed on surfaces of solvothermally synthesized nano-particles of LiMnPO4. The hybrid-coated LiMnPO4 realizes excellent rate-capabilities and good cyclability at 25°C, enabling discharge capacities as high as 159 mAh g−1 at 0.1C, 147 mAh g−1 at 1C and 111 mAh g−1 even at 10 C, which surpass those ever reported for LiMnPO4. These performances could be promoted by high 3D conductivities both of electron and Li ion in the hybrid-coated layers.