Patent ID: 7951490

Claim:
A secondary battery, comprising: a cathode including a stable complex oxide and a stable conductive oxide; an anode including an anode active material capable of inserting and extracting lithium; and a nonaqueous electrolyte, wherein, z the stable complex oxide includes (a) lithium, (b) nickel, (c) manganese, (d) a first element including at least one kind selected from the group consisting of elements in Group 2 through Group 14, and (e) oxygen, the composition of nickel, manganese and the first element in the stable complex oxide are within a range defined by the formula Ni 1-y-z Mn y MI z , where MI represents the first element and the values of y and z are within a range of 0.25<y<0.45 and 0.01<z<0.30, respectively, the conductive complex oxide includes (a) lithium, (b) a second element including at least one kind selected from the group consisting of nickel and cobalt (Co), (c) manganese, (d) a third element including at least one kind selected from the group consisting of elements in Group 2 through Group 14 and (e) oxygen, the composition of the second element, manganese and the third element in the conductive complex oxide is defined by the formula MII 1-t-u Mn t MIII u where MII and MIII represent the second element and the third element, respectively, and the values of t and u are within a range of 0.05<t<0.20 and 0.01<u<0.10, respectively, and the third element includes Ni w , where w>0.5.