| abstract |
Provided is a positive electrode active material for a lithium ion secondary battery having a high capacity and excellent charge / discharge cycle characteristics. It is a positive electrode active material having lithium, cobalt, element X and fluorine, and has a region represented by a layered rock salt type structure, in which the space group is represented by R-3 m, and the element X is lithium cobalt oxide. ΔE3, which is the value obtained by subtracting the stabilization energy before replacement from the stabilization energy when replaced with the lithium position, is the stabilization energy before replacement from the stabilization energy when replaced with the cobalt position of lithium cobalt oxide. It is one or more selected from the elements having properties smaller than the subtracted value of ΔE4, and ΔE3 and ΔE4 are calculated by the first-principles calculation. |