▎ 摘　　要

NOVELTY - Graphene composite hydrogel comprises graphene and mesoporous carbon nanospheres having a mass ratio of 1-4:1. USE - The graphene composite hydrogel useful in an all-solid-state supercapacitor (claimed). ADVANTAGE - The graphene composite hydrogel: obtains all-solid-state supercapacitor by assembling the composite hydrogel, which has high volume energy density, good flexibility, and improves its capacitance performance under sunlight. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) preparing the graphene composite hydrogel, comprising (i) dispersing graphene oxide and mesoporous carbon nanospheres in water at a mass ratio of 1-4:1, stirring, and using a probe ultrasound to disperse uniformly to obtain a dispersion and the concentration of graphene oxide in the dispersion is 1-3 mg/ml, and (ii) adding a weak reducing agent to the dispersion in step (i), then carrying out hydrothermal reaction, and the mass ratio of the weak reducing agent to the graphene oxide in the step (i) is 2-5:1; (2) use of a composite hydrogel in an all-solid-state supercapacitor; and (3) all-solid-state supercapacitor, comprising the composite hydrogel, which is prepared into an arbitrary shape through a mold, and after washing, directly pressing the electrode on a stainless steel net to prepare an electrode, coating the pressed electrode with a polymer electrolyte, and assembling after drying.