▎ 摘　　要

NOVELTY - A positive electrode (20) comprises a current collector (22), and a layer (24) comprising an active material of a lithium-nickel-cobalt-manganese composite oxide (I) and graphene or multilayer graphene, provided on a surface of the current collector. The positive electrode active material comprises a particle group (A1) comprising particles having a particle diameter of 1/2 or less of an average particle diameter of graphene or multilayer graphene. At least one portion of group (A1) is adhered to a surface of graphene or multilayer graphene. USE - Positive electrode is used for lithium-ion secondary battery (claimed) for portable electronic device, hybrid vehicle, and electric vehicle. ADVANTAGE - The positive electrode can improve output characteristics and cycle characteristics of the lithium-ion secondary battery, and has suppressed deterioration of the positive electrode active material layer in charging/discharging cycle of the battery. DETAILED DESCRIPTION - A positive electrode comprises a current collector, and a layer comprising an active material of a lithium-nickel-cobalt-manganese composite oxide of formula: LiaNibCocMnd(M)eO2 (I) and graphene or multilayer graphene, provided on a surface of the current collector. The positive electrode active material comprises a particle group (A1) comprising particles having a particle diameter of 1/2 or less of an average particle diameter of graphene or multilayer graphene. At least one portion of group (A1) is adhered to a surface of graphene or multilayer graphene. M = Al, Si, Zr, Ti, Fe, Mg, Nb, Ba and/or V; a+b+c+d+e = 1.9-2.2; a = 0-1.3 (excluding 0); b = 0.5-1; c = 0-1; d = 0-0.7;and e = 0-0.2. DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional schematic view of the lithium-ion secondary battery. Separator (10) Positive electrode (20) Positive current collector (22) Positive electrode active material layer (24) Lithium-ion secondary battery (100)