Physical and electrochemical properties of LiCoPO4/C nanocomposites prepared by a combination of emulsion drip combustion and wet ball-milling followed by heat treatment

Abstract

The combination of emulsion drip combustion at 600 °C and wet ball-milling followed by heat treatment at 500 °C in a N2 + 3% H2 atmosphere was performed for the preparation of LiCoPO4/C nanocomposites. The obtained material consisted of agglomerates of LiCoPO4 primary particles with a geometric mean diameter of 70 nm, which were covered by a thick layer of amorphous carbon. A cell containing the LiCoPO4/C nanocomposites exhibited a discharge capacity of 134 mAh g−1 at a charge-discharge rate of 0.1 C. However, the discharge profile of the LiCoPO4/C nanocomposites had a long tail, which may be due to the limited lithium ion diffusion caused by the thick carbon layer that formed on the LiCoPO4 primary particles. The LiCoPO4/C nanocomposites prepared from a mixture of kerosene and heptane with equal volumes consisted of agglomerates of the primary particles with a geometric mean diameter of 97 nm, which were covered by a thin layer of amorphous carbon with a thickness on the order of 10 nm. Furthermore, they delivered a high energy density of 595 Wh kg−1 at a charge–discharge rate of 0.1 C and exhibited reasonable cyclability, retaining 87% of the initial energy density after 25 cycles.