Application of Naphthoquinone Derivatives Non-Covalently Modified Graphene Nanosheets in Asymmetric Supercapacitors

Abstract

As an organic pseudocapacitive active material, 2, 3-Dichloro-1, 4-naphthoquinone (DNQ) was used in supercapacitors. Graphene with unique structures and high electrical conductivity acts as substrate. DNQ non-covalently modified graphene composite material (DNQ@rGO) was synthesized through the simple solvothermal synthesis. The redox reaction between naphthol and naphthoquinone occurs on reduced graphene oxide(rGO), which forms an ideal pseudocapacitance without destroying its sp² network. The optimal DNQ@rGO electrode material obtained the specific capacitance of 361.2 Fg⁻¹ at 5 mV s⁻¹ in 1 mol L⁻¹ H₂SO₄ and exhibited excellent rate capability (capacitance retention of 87.5 % at 100 mV s⁻¹) in the three-electrode system. We also prepared holey layered oxygen-rich graphene hydrogels (HLGH) material, whose electrochemical performance is superior to traditional three-dimensional (3D) graphene hydrogels (GH). Finally, two asymmetric supercapacitors (ASCs) were assembled by using the DNQ@rGO (positive electrode), the HLGH and GH (negative electrode). The results show that the ASC with HLGH as negative electrode achieved the high energy and power densities due to the perfect matching of capacitance and kinetics between the positive and negative electrodes. The specific capacitance was almost no loss after 4700 cycles, showing the excellent stability.