| abstract |
A lithium ion secondary battery according to the present invention uses a cathode material obtained by mixing a first cathode active substance represented by a compositional formula: Li x1 Ni a1 Mn b1 CO c1 O 2 (in which 0.2≦x 1 ≦1.2, 0.6≦a 1 ≦0.9, 0.05≦b 1 ≦0.3, 0.05≦c 1 ≦0.3, and a 1 +b 1 +c 1 =1.0); and a second cathode active substance represented by a compositional formula: Li x2 Ni a2 Mn b2 CO c2 M d O 2 (in which 0.2≦x 2 ≦1.2, 0.7≦a 2 ≦0.9, 0.05≦b 2 ≦0.3, 0.05≦c 2 ≦0.3, M=Mo, W, 0≦d≦0.06, and a 2 +b 2 +c 2 +d=1.0). |