| abstract |
A positive electrode active material having a high capacity and excellent cycle characteristics is provided. A positive electrode active material includes secondary particles in which a plurality of primary particles are aggregated. The primary particles include core particles that include a lithium composite oxide, and a layer that is provided on the surface of the core particles and includes a lithium composite oxide. The lithium composite oxide contained in the core particle and the lithium composite oxide contained in the layer have the same composition or almost the same composition. The crystallinity of the lithium composite oxide contained in the layer is lower than the crystallinity of the lithium composite oxide contained in the core particles. [Selection] Figure 1 |