▎ 摘　　要

NOVELTY - Manufacturing (M1) an electrode, comprises: forming an active material layer over a current collector, where the active material a comprises a particle and a piece of graphene oxide covering the particle; impregnating the active material layer with alcohol; and performing heat treatment on the active material layer after impregnating the active material layer, where the particle comprises an inner region and a surficial region after the heat treatment, the inner region comprises a crystal having a layered rock-salt crystal structure, the surficial region comprises a crystal having a spinel crystal structure, and the surficial region is in contact with the piece of graphene oxide is reduced. USE - The method is useful for manufacturing an electrode (claimed) which is used in semiconductor device, a display device, a light-emitting device, an imaging device, a power storage device and a memory device. ADVANTAGE - The method: provides storage batteries that has room for improvement in charge and discharge characteristics, cycle performance, reliability, safety and cost; increases the capacity per volume and/or weight of a power storage device; utilizes positive electrode active material that achieve high energy density; provides power storage device in which a decrease in capacity in charge and discharge cycles is inhibited; and provides positive electrode active material that can be formed at low cost. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for manufacturing (M2) an active material, comprising covering an active material particle with a piece of graphene oxide, impregnating the active material particle covered with the piece of graphene oxide, performing heat treatment on the active material particle after the impregnating step, where the active material particle comprises an inner region and a surficial region after the heat treatment, the inner region comprises a crystal having a layered rock-salt crystal structure, the surficial region comprises a crystal having a spinel crystal structure, and the surficial region is in contact with the piece of graphene oxide is reduced.