SECONDARY BATTERY

A secondary battery including a positive electrode including a positive electrode active material capable of electrochemically absorbing and releasing lithium ions, a negative electrode including a negative electrode active material capable of electrochemically absorbing and releasing lithium ions, a separator interposed between the positive and negative electrodes, and a non-aqueous electrolyte. The positive electrode includes a positive electrode material mixture containing the positive electrode active material and a positive electrode additive. The positive electrode additive includes a compound represented by LiFeMO, where 0≤a≤5, 0≤x≤5, 0≤y≤1, and 0≤z≤4, with at least two of a, x, y and z being more than 0, and M includes at least one kind selected from the group consisting of Mn, Zn, Al, Ga, Ge, Ti, Si, Sn, Ce, Y, Zr, S, and Na.