| 摘要 |
PURPOSE:To enable obtaining a secondary battery having high energy density, a small self-discharge rate and long cycle lifetime by using sodium-cobalt oxide for a positive electrode. CONSTITUTION:A material comprising a sodium-cobalt oxide made from a mixture of Na salt and Co3O4, particularly a material having the gamma-type crystalline construction wherein one Na or Co atom, and six oxygen atoms sandwiching the Na or Co atom shows a triangular prism type, is used as the positive electrode material of a secondary battery. For the manufacture of the sodium-cobalt oxide, it is preferable to well mix sodium salt, sodium oxide or sodium peroxide with a cobalt oxide, and cause the reaction thereof in a gradual baking process in a low humidity condition and under dry air or oxygen atmosphere. According to the aforesaid construction, it is possible to obtain a secondary battery having high energy density, long cycle lifetime and yet a small self-discharge rate. |
