▎ 摘　　要

NOVELTY - A reduced graphene oxide film comprises a three-dimensional hierarchy of pores, and has an active density of up to 0.5 g/cm3. USE - Reduced graphene oxide film is used for forming electrode of supercapacitor device (claimed). Uses include but are not limited to cell phone, computer, camera, pacemaker, defibrillator, hearing aid, pain management device, drug pump, electric vehicle, military energy storage device, electric aircraft, grid scale energy storage, back-up power, cold starting, flash camera, regenerative braking vehicle, hybrid electric vehicle, solar cell array, flexible display, wearable electronic, etc. ADVANTAGE - The reduced graphene oxide film enables simple, versatile and direct fabrication of supercapacitor device with excellent performance, and high energy density and power density, by filtration and freeze casting. The supercapacitor device avoids shortcoming of current energy storage technology. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) supercapacitor device, which comprises two electrodes (502,505) comprising the reduced graphene oxide film, an electrolyte (503), and an separator (504) arranged between the electrodes; and (2) fabrication of graphene oxide film, which involves suspending a graphene oxide in a solvent (s1) to form a graphene oxide suspension, dispersing the graphene oxide suspension in a solvent (s2) to form a graphene oxide dispersion, reducing the graphene oxide dispersion, filtering the graphene oxide dispersion through a membrane to form a graphene oxide film on the membrane, and freeze-casting the graphene oxide film on the membrane. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the symmetric two-electrode supercapacitor device. Current collectors (501,506) Electrodes (502,505) Electrolyte (503) Separator (504)