In situ hydrothermal construction of hydrogel composites by anchoring Ni(OH)2 nanoparticles onto sulfonated graphene and their application for functional supercapacitor electrode

Abstract Graphene oxide derived from Hummer method has some irreversible defects such as easy accumulation and excessive oxygen-containing groups, which leads to deterioration of the electrochemical performance of graphene oxide, and sulfonated graphene can effectively overcome aforementioned shortcomings. Herein, sulfonated graphene is obtained by modifying graphene oxide with aryl diazonium salt of sulfanilic acid, and the hydrogel composite formed by anchoring Ni(OH) 2 on sulfonated graphene is prepared by means of hydrothermal method. The results show that, when the mass ratio of sulfonated graphene to Ni(OH) 2 is 1:5, the hydrogel composite can provide excellent electrochemical performance. The electrode material achieves a high specific capacitance of 1817.5 F g −1 at a current density of 1 A g −1 , and still has excellent cycle stability at higher current densities. At a current density of 10 A g −1 , its capacitance retention rate is as high as 89.5% after 1000 cycles, indicating that the electrode material has great potential in the field of supercapacitors. A laboratory-made all-solid-state flexible SGN//AC asymmetric supercapacitor exhibits a high specific capacitance of 80.44 F g −1 at 50 mA g −1 , a large energy density and power density, and a stable cycle life. Three supercapacitors in series can lighten up a green LED indicator.