Positive electrode active material and positive electrode for nonaqueous electrolyte secondary battery

Abstract

Provided is a positive electrode active material which inhibits a decrease in discharge capacity while improving output in a low SOC region. The positive electrode active material includes: first particles that each consist of a first lithium transition metal composite oxide, the first lithium transition metal composite oxide having a layered structure and having a ratio of a number of moles of nickel to a total number of moles of metals other than lithium in a composition thereof being 0.7 or greater and smaller than 1; second particles that have a volume average particle diameter smaller than a volume average particle diameter of the first particles, the second particles each consisting of a second lithium transition metal composite oxide having a layered structure; and third particles that each consist of a third lithium transition metal composite oxide, the third lithium transition metal composite oxide having a layered structure, having a ratio of number of moles of nickel to total number of moles of metals other than lithium in a composition thereof being 0.4 to 0.6, and having a ratio of a number of moles of cobalt to the total number of moles being 0.35 to 0.55. The first particle content is 60 mass % or higher and lower than 100 mass %, and the third particle content is 10 mass % or lower, to a total content of the first particles, the second particles, and the third particles.