Patent ID: 7316862

Claim:
An active material for an electrode, comprising: a lithium-containing complex oxide A represented by General Formula: Li 1+x+α Ni (1−x−y−δ)/2 Mn (1−x−y−δ)/2 M y O 2 (where 0≦x≦0.15, −0.05≦x+α≦0.2, 0≦y≦0.4; −0.1≦δ≦0.1; and M is at least one element selected from the group consisting of Mg, Ti, Cr, Fe, Co, Cu, Zn, Al, Ge, Zr and Sn), the lithium-containing complex oxide A comprising secondary particles formed of flocculated primary particles, the secondary particles having a mean particle diameter of 5 to 20 μm, Mn having an average valance of 3.3 to 4; and a lithium-containing complex oxide B having a mean particle diameter smaller than the mean particle diameter of the secondary particles of the lithium-containing complex oxide A, the lithium-containing complex oxide B having a different composition from the lithium-containing complex oxide A and being represented by General Formula: Li 1+a+b R 1−a O 2 (where 0≦a≦0.05 and −0.05≦a+b≦0.05; and R is Co and at least one element selected from the group consisting of Mg, Ti, Cr, Fe, Cu, Zn, Al, Ge, Zr and Sn).