Abstract: Lithium ion batteries were intensively used in the field of portable computer and communication. If one doubles the specific capacity of the positive electrode, e.g. by using an oxide that could reversibly intercalate 1 Li instead of 0.5 Li per 3d-metal, one could increase the specific capacity of the cell by 68%. In contrast, if one doubles the specific capacity of the negative electrode, one could increase the overall specific capacity of the cell by only 12%. Thus, to improve the specific capacity of lithium ion batteries, we should dedicate our effort to the synthesis of new positive electrode materials, i.e.. Vacious lithiated oxides that could reversibly intercalate one Li atom per 3d-metal atom at about 4 Vversus Li. LiMn₂O₄is a promising candidate for cathode because of its high voltage, low coat and nonpolluting for environment. Sol-gel method is used to synthesize the cathode materials recently. The material has a high first-discharge capacity and long cycle life, and the synthetic process is simple: it reacts at a low temperature and the sample particle is uniform in size.

Key words: Lithium ion batteries, Cathode material, LiMn₂O₄, Specific capacity