▎ 摘　　要

NOVELTY - Three-dimensional graphene structure preparation involves forming graphene precursor by heating a carbohydrate and a gas generator, forming a graphene structure having a cavity (110A) by carbonizing the graphene precursor, and then forming nanopores (120B) in the graphene structure. The nanopores pass through an outer surface and an inner surface of the graphene structure, and are connected with the cavity. USE - Method for preparing three-dimensional graphene structure. ADVANTAGE - The method prepares the three-dimensional graphene structure in a simple and cost-effective manner. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for an energy storage device, which comprises an electrode structure (1000) including current collector and graphene structure disposed on the current collector, another electrode structure (2000) spaced apart from the former electrode structure, a separation film (4000), and an electrolyte (3000) interposed between the former electrode structure and the latter electrode structure. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic cross-sectional view of the energy storage device. Cavity (110A) Nanopores (120B) Electrode structures (1000,2000) Electrolyte (3000) Separation film (4000)