| 摘要 |
PURPOSE:To enhance an improvement in cycle characteristic and an increase in capacity by acid-treating a spinel manganese oxide obtained by heat-treating a starting material containing stoichiometrically excessive manganese at high temperature to remove manganese trivalent or less. CONSTITUTION:LiCO3 and Mn2O3 powder are used as starting materials, and they are mixed in a mole ratio of 1:2.1 to make the manganese content more excessive than the stoichiometric composition ratio of Li to Mn on the basis of mole ratio, and a high-temperature heat treatment in an inert gas atmosphere is conducted to obtain a spinel manganese oxide. This is mixed to a heated sulfuric acid aqueous solution, and then washing with water, filtration and drying are carried out to obtain a positive electrode active material. Hence, the manganese component trivalent or less in the crystal structure is eluted into the acid treatment solution to form pores on the crystal surface, which thus becomes porous. Consequently, the lithium ion on negative electrode side can freely be delivered into the crystal lattice, resulting in an improvement in cycle characteristic and an increase in capacity. |
