Redox-active p-phenylenediamine functionalized reduced graphene oxide film through covalently grafting for ultrahigh areal capacitance Zn-ion hybrid supercapacitor

Abstract Graphene film electrode usually suffers from undesirable electrochemical performance due to its agglomeration effect and electrical double layer storage mechanism. Here, the p-phenylenediamine (PPD) is adopted as a redox-active spacer to simultaneously alleviate these problems. Specifically, PPD is introduced into the interlayer of graphene film, which is favorable to enhance the interlayer distance and consequently expose more ion accessible area. Moreover, the redox-active nature of PDD endows graphene film with tremendous pseudocapacitance by a reversible redox reaction with electrolyte ions. Benefiting from these advantages, the fabricated Zn-ion hybrid supercapacitors (ZHSs) by combing the PPD functionalized reduced graphene oxide (RGO) film (RGO@PPD (6:7)) positive electrode and Zn foil negative electrode displays remarkable areal capacitance of 3012.5 mF cm−2 and a high energy densities of 1.1 mWh cm−2 at power densities of 0.8 mW cm−2. This organic molecule covalent bond decoration approach opens up a new way for improving the electrochemical performance of the graphene film for advanced ZHSs.