Characteristics of coke carbon modified with mesophase-pitch as a negative electrode for lithium ion batteries

To increase the charge–discharge capacity of carbon electrodes for lithium ion secondary batteries, coke carbon, a relatively cheap material, was modified with mesophase-pitch carbon by a heat treatment. While coke carbon powder, mesophase-pitch, and a mixture thereof (4:1 by weight) supplied between 0 and 1.5 V vs. Li/Li+ an initial discharge capacity of about 295 mAh/g, 310 mAh/g, and 310 mAh/g, respectively, the modified coke deintercalated 400 mA h/g of lithium with a high degree of reversibility. The difference in capacity between the modified carbon and mixture are discussed based on the shape of their current–potential curves and their galvanostatic charge–discharge curves.