High voltage, rechargeable lithium batteries using newly-developed carbon for negative electrode material

Carbon is a good candidate for negative electrodes because it can take the form of lithium intercalation compounds. We discussed the characteristics of typical carbon materials which have been studied as negative electrode materials. We have found that the mesophase pitch-based carbon microbead (MCMB) of high graphitization stage which have been graphitized at a high temperature such as 2800 °C gives good characteristics as a negative electrode for rechargeable lithium batteries. The cylindrical ‘AA-size’ batteries of our trial products using LiCoO2 as the positive electrode and the MCMB graphitized at 2800 °C as the negative electrode have been found to provide large capacities of 500 mA h and high voltages of 3.7 V with high energy densities of 240 W h/l, 100 W h/kg.