▎ 摘　　要

NOVELTY - Preparing a supercapacitor involves preparing a graphene film on a substrate (S1); optionally transferring the graphene film to a substrate (S2), which is different from the substrate (S1); preparing in-plane graphene electrodes of interdigital structure and at least one current collector of interdigital structure; and adding an electrolyte such that the electrolyte is in contact with the in-plane graphene electrodes of interdigital structure. USE - For preparing a supercapacitor (i.e. a micro supercapacitor) as energy storage device (claimed). Also useful for filtering applications. ADVANTAGE - The supercapacitor has high power density but still results in high energy delivery and achieves high discharge rates. DETAILED DESCRIPTION - Preparing a supercapacitor involves preparing a graphene film on a substrate (S1); optionally transferring the graphene film to a substrate (S2), which is different from the substrate (S1); preparing in-plane graphene electrodes of interdigital structure and at least one current collector of interdigital structure by providing on the graphene film, a mask with a mask pattern which leaves at least one graphene area of interdigital structure uncovered, applying the current collector onto the graphene area of interdigital structure and removing the mask, and removing the parts of the graphene film which are not covered by the current collector; and adding an electrolyte such that the electrolyte is in contact with the in-plane graphene electrodes of interdigital structure. The graphene film is prepared by preparing a graphene oxide, coating the substrate S1 with the graphene oxide so as to obtain a graphene oxide film, and reducing the graphene oxide film by treatment with plasma so as to obtain the graphene film. The parts of the graphene film which are not covered by the current collector are removed by plasma etching; and/or the electrolyte is a non-liquid electrolyte, preferably a polymer gel electrolyte. INDEPENDENT CLAIMS are included for the following: (1) a supercapacitor comprising: a substrate; in-plane graphene electrodes of interdigital structure, and having a lower surface, which is in contact with the substrate, and an upper surface, and having a maximum thickness of less than 1000 nm; at least one current collector of interdigital structure, which is at least partially covering the upper surface of the graphene electrodes; and an electrolyte which is in contact with the in-plane grapheme electrodes of interdigital structure; (2) preparing (p1) a layered assembly, involving: preparing on a first substrate S1 a graphene film which has a lower surface being in contact with the substrate S1 and an upper surface being at least partially uncovered; and transferring the graphene film from the substrate S1 to a substrate S2, which is different from the substrate S1, by providing a temporary material on the upper surface of the graphene film, followed by removal of the substrate S1 so that the graphene film now has an uncovered lower surface and an upper surface which is in contact with the temporary material, subsequently applying the substrate S2 onto the lower surface of the graphene film, followed by removal of the temporary material from the upper surface of the graphene film; (3) a layered assembly comprising a substrate and a graphene film on the substrate, and is obtainable by the method (p1); and (4) use of the layered assembly for manufacturing an energy storage device, preferably supercapacitor.