| abstract |
A lithium ion secondary battery having good load characteristics even after initial charging is provided. [Solution] A lithium ion secondary battery 100 provided by the present invention has a structure in which a positive electrode 10, a negative electrode 20, and a non-aqueous electrolyte are accommodated in a battery case 50. The positive electrode 10 is, as a positive electrode active material, Li 2 there MnO 3 manganese-containing solid solution solid solution by the general formula Li x [Mn (1-y ) M y] O z (M is at least one other than Li and Mn A lithium manganese oxide represented by 1 <x <2, 0 ≦ y <1, 1.5 <z <3). Inside the battery case 50, at least one reducing gas capable of reducing oxygen is disposed. [Selection] Figure 1 |