Lithium-containing complex oxide, non-aqueous secondary battery using the lithium-containing complex oxide, and method for producing the lithium-containing complex oxide

A method for producing a lithium-containing complex oxide, comprising:

• coprecipitating a complex compound containing at least Ni and Mn as constituent elements in an inactive atmosphere;
• mixing the complex compound and a compound of Li at a predetermined ratio;
• and
• sintering the mixture at a sintering temperature of about 700° C. to 1100° C. in an atmosphere containing oxygen, thereby forming a complex oxide with a layered crystal structure,
• wherein the lithium-containing complex oxide further contains a substituent element M,
• wherein the substituent element M contains Co, and assuming that a total quantity of Ni, Mn, and the substituent element M is 1-x, and a quantity ratio of the substituent element M is y, x satisfies 0≦x≦0.05, y satisfies 0.1<y≦0.4, and a quantity ratio of Co is 0.1 or more,
• wherein a composition of the complex compound containing at least Ni and Mn as constituent elements is adjusted so that a difference δ in a quantity ratio between Ni and Mn constituting the lithium-containing complex oxide satisfies −0.1≦δ≦0.1, and
• wherein an average valence of Mn constituting the lithium-containing complex oxide is set to be about 3.3 to 4.