| 摘要 |
PROBLEM TO BE SOLVED: To provide a lithium secondary battery of large capacity, high voltage and large energy density using a negative electrode active material showing large capacitive density and a base electrode potential, by setting the lithium content in a lithium-containing composite nitride at a value larger than a specific value during the operation of the battery. SOLUTION: A lithium-containing composite nitride is prepared by heating a mixture of a lithium nitride and a metal element other than lithium under nitrogen atmosphere and can be expressed in the general formula, LiαMβN (M is a metal component other than lithium, α is a lithium content changing with charge and discharge and a variable, β is a substituted amount of M and a constant). The lightium content α is >3.0 while a battery is in operation. For example, nitride lithium cobaltate is a compound prepared by mixing and heating the prescribed amounts of lithium nitride powder and metal cobalt powder, in a form of a part of lithium of Li3 N substituted by cobalt. A synthesized product is a non-stoichrometric compound of α=3-β. In this case, βis a positive real number <=3. |
