US Patent 7976983 Lithium ion secondary battery

A lithium ion secondary battery including a positive electrode including a lithium composite oxide represented by the general formula (1): LixM1-yLyO2 (0.85≦x≦1.25 and 0≦y≦0.50; M is at least one selected from the group consisting of Ni and Co; and L is at least one selected from the group of alkaline earth elements, transition elements other than Ni and Co, rare earth elements, and elements of Group IIIb and Group IVb). The lithium composite oxide is treated with a coupling agent having a plurality of hydrolyzable groups, and the remaining hydrolyzable group is inactivated.