A parameter for producing a positive electrode having excellent safety, and a positive electrode active material layer satisfying the parameter. The positive electrode active material layer includes a first positive electrode active material, a second positive electrode active material having a lower charge/discharge potential than the first positive electrode active material, and an additive. When the first positive electrode active material tap density is defined as dt1, the second positive electrode active material tap density is defined as dt2, a true density of the additive is defined as d3, a mass percentage of the first positive electrode active material is defined as Wt1, a mass percentage of the second positive electrode active material is defined as Wt2, a mass percentage of the additive is defined as Wt3, and a porosity of the positive electrode active material layer is defined as p, the positive electrode active material layer satisfies (1−p)×(Wt1/dt1)/((Wt1/dt1)+(Wt2/dt2)+(Wt3/d3))