Patent 7442469 was granted and assigned to Sony on October, 2008 by the United States Patent and Trademark Office.
A cathode with a cathode active material is provided. The cathode active material is obtained by mixing a zirconium-containing lithium cobalt composite oxide containing zirconium as a sub-component element in a first lithium cobalt composite oxide expressed by a formula LitCoMsO2 (where M is at least one kind of element selected from Fe, V, Cr, Ti, Mg, Al, B, and Ca; 0≦s≦0.03; 0.05≦t≦1.15), and a second lithium cobalt composite oxide expressed by a formula LixCol-yAyO2 (where A is at least one kind of element selected from Mg and Al; 0.05≦x≦1.15; 0≦y≦0.03).