Redox molecule modified graphene hydrogel with structure controllable for high-performance aqueous zinc-ion hybrid capacitors via utilizing hydrothermal fluid behavior

Abstract

Redox Molecule modified graphene-based materials exhibit excellent electrochemical performance due to the synergistic effect of pseudocapacitance and double layer energy storage mechanism in aqueous zinc-ion hybrid capacitors (AZIHCs). Herein, the 2, 6-Diaminoanthraquinone (DQ) modified flexible graphene hydrogel materials (DQ-FGH) with controllable structure are prepared via utilizing hydrothermal fluid behavior. Specifically, the temperature difference inside the DQ@GO suspension can cause convection in hydrothermal processes. The convection form of the suspension is regulated by controlling the volume of the suspension. Thus the DQ@GQ nanosheets can be reduced and assembled into the DQ-FGH films with different structures during convection. The prepared films show an excellent specific capacitance of 317.25 F g⁻¹ (@0.2 A g⁻¹) and a promising rate performance, which exceeds unmodified graphene-based material by 35.7 %. When the mass loading is closed to commercial level, the areal capacitance of the DQ-FGH films can reach 1850 mF cm⁻². Moreover, the flexible AZIHCs based on the DQ-FGH films also possess good mechanical stability and electrochemical performance, proving good application prospects.