Effect of carbon addition on one-step mechanical synthesis of LiCoPO4/C composite granules and their powder characteristics

Lithium cobalt phosphate, LiCoPO4, has attracted much attention as a high voltage cathode material in lithium-ion batteries (LIBs). Since this material suffers from very low ion and electron conductivities, the composite structure made with nano-sized LiCoPO4 and carbon can be effectively used as a cathode material. Here, we report a simple mechanical synthesis route for preparing LiCoPO4/C composite granules. The raw materials for LiCoPO4 and carbon were mechanically treated with an attrition-type mill for producing LiCoPO4/C composite granules using a one-step process without employing external heating. With an increase in the amount of carbon used, the primary particle size of LiCoPO4 and the median size of granules were decreased. The first discharge capacity obtained for the LiCoPO4/C prepared with 5 mass% carbon was 105 mA h g−1, whereas a value of up to 134 mA h g−1 was obtained for the composite with 10 mass% carbon. We examined the effect of carbon addition on the mechanical synthesis and characteristics of LiCoPO4 powders.