| 摘要 |
PROBLEM TO BE SOLVED: To improve structural stability and thermal stability by forming a positive electrode material by coating the surface of a lithium-cobalt based compound comprising secondary particles of a specific size in each of which one or more primary particles of a specific size are aggregated with a metal compound. SOLUTION: The sizes of primary and secondary particles of a Li-Co based compound expressed by the formulas I-IV are 1-5 μm and 10-30 μm, respectively, and a metal oxide of Mg, Al, Co, K, Na, Ca, Si, Ti and V is preferably used for a metal compound for coating. In the formulas, A is O, S, F or P; B is S, F or P; M is a metal such as Al, Mg, Cr or Mn, or a lanthanoid metal such as La or Ce; 0<x<1; and 0<y<1. A coating effect by virtue of the increase of the specific surface area of an active material is enchanced, and the decomposition temperature of oxygen bonded with the metal is raised, so that a heating value is reduced. It is recommended that heat treatment is carried out in an atmosphere of the air or oxygen at a predetermined temperature after coating the compound with a metal alkoxide solution or aqueous solution. |
