Positive electrode material for lithium-ion secondary batteries, positive electrode for lithium-ion secondary batteries, and lithium-ion secondary battery

Abstract

A positive electrode material for lithium-ion secondary batteries, wherein the positive electrode material includes a carbon-coated positive electrode active material which comprises primary particles, secondary particles, and a carbon film, wherein the primary particles and the secondary particles are coated with the carbon film, wherein the primary particles consists of a positive electrode active material in which a strain of the positive electrode active material, which is calculated by X-ray diffraction measurement, is 0.01% or higher and 0.1% or lower, and a ratio (B/A) of a crystallite diameter B (nm) of the positive electrode active material to an average primary particle diameter A (nm) of the carbon-coated positive electrode active material is 0.9 or higher and 1.5 or lower, wherein the particle diameter A is calculated from a specific surface area of the carbon-coated positive electrode active material, wherein the specific surface area is obtained using a BET method.