| abstract |
A positive electrode having a positive electrode active material and a positive electrode current collector; And a negative electrode opposed to the positive electrode in a state where an electrolyte is provided between the positive electrode and the positive electrode. The positive electrode active material includes a first region comprising a phosphoric acid compound containing lithium and nickel; And a second region covering the first region and comprising a compound containing at least one of lithium, iron, manganese, and cobalt, but no nickel. Since the entire surface portion of the particles of the positive electrode active material does not contain nickel, nickel does not contact the electrolyte solution; Therefore, the occurrence of the catalytic effect of nickel can be suppressed, and a high discharge potential of nickel can be used. |