POSITIVE ELECTRODE ACTIVE MATERIAL, BATTERY, AND METHOD FOR PRODUCING POSITIVE ELECTRODE ACTIVE MATERIAL

A positive electrode active material comprising a plurality of secondary particles, wherein: each of the secondary particles includes a plurality of primary particles; each of the primary particles contains an olivine-type phosphate compound; carbon is attached to at least part of a surface of the primary particle; a cross-sectional surface of the secondary particle includes a central portion and a peripheral portion; and a relationship of 0.5≤I/Iis satisfied where Iis an average value of signal intensities of carbon in the central portion in TEM-EDS line analysis along a diametrical direction of the secondary particle, and Iis an average value of signal intensities of carbon in the peripheral portion in TEM-EDS line analysis along the diametrical direction of the secondary particle.