Patent ID: 8404211

Claim:
A method for producing a lithium-containing composite oxide represented by General Formula (1): Li x M y Me 1−y O 2+δ (1) where M represents at least one element selected from the group consisting of Ni, Co and Mn, Me represents a metal element that is different from M, δ represents a deficit or excess of oxygen, −0.1≦δ≦0.1, 0.95≦x≦1.10 and 0.1≦y≦1, the method comprising the steps of: baking a lithium compound and a compound that contains M and Me to obtain a baked product; and washing said baked product with a washing solution that contains one or more water-soluble polar aprotic solvents selected from the group consisting of water-soluble polar aprotic solvents represented by the following General Formulas (2) to (8): where R 1 and R 2 each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, or R 1 and R 2 are bonded to each other and represent an alkylene group having 3 to 6 carbon atoms that forms a ring with a nitrogen atom; R 3 represents an alkyl group having 1 to 3 carbon atoms or a cycloalkyl group having 4 to 7 carbon atoms; R 4 and R 5 each independently represent a methyl group or an ethyl group; R 6 and R 7 each independently represent a methyl group or an ethyl group, or R 6 and R 7 are bonded to each other and represent an alkylene group having 2 to 4 carbon atoms that forms a ring with two nitrogen atoms and a carbonyl carbon; R 8 and R 9 each independently represent a methyl group or an ethyl group, or R 8 and R 9 are bonded to each other and represent an alkylene group having 4 to 6 carbon atoms that forms a ring with a sulfur element; R 10 and R 11 each independently represent a hydrogen atom, a methyl group or an ethyl group; R 12 represents an alkyl group having 1 to 3 carbon atoms; R 13 represents an alkylene group having 2 to 4 carbon atoms; Z represents an oxygen atom or a methylene group, and m and n each independently represent an integer from 1 to 3.