Fabrication of Flexible Poly(<i>m</i>-aminophenol)/Vanadium Pentoxide/Graphene Ternary Nanocomposite Film as a Positive Electrode for Solid-State Asymmetric Supercapacitors

In this study, poly(m-aminophenol) (PmAP) has been investigated as a multi-functional conductive supercapacitor binder to replace the conventional non-conductive binder, namely, poly(vinylene difluoride) (PVDF). The kye benefits of using PmAP are that it is easily soluble in common organic solvent and has good film-forming properties, and also its chemical functionalities can be involved in pseudocapacitive reactions to boost the capacitance performance of the electrode. A new ternary nanocomposite film based on vanadium pentoxide (V2O5), amino-functionalized graphene (amino-FG) and PmAP was fabricated via hydrothermal growth of V2O5 nanoparticles on graphene surfaces and then blending with PmAP/DMSO and solution casting. The electrochemical performances of V2O5/amino-FG/PmAP nanocomposite were evaluated in two different electrolytes, such as KCl and Li2SO4, and compared with those of V2O5/amino-FG nanocomposite with PVDF binder. The cyclic voltametric (CV) results of the V2O5/amino-FG/PmAP nanocomposite exhibited strong pseudocapacitive responses from the V2O5 and PmAP phases, while the faradaic redox reactions on the V2O5/amino-FG/PVDF electrode were suppressed by the inferior conductivity of the PVDF. The V2O5/amino-FG/PmAP electrode delivered a 5-fold greater specific capacitance than the V2O5/amino-FG/PVDF electrode. Solid-state asymmetric supercapacitors (ASCs) were assembled with V2O5/amino-FG/PmAP film as a positive electrode, and their electrochemical properties were examined in both KCl and Li2SO4 electrolytes. Although the KCl electrolyte-based ASC has greater specific capacitance, the Li2SO4 electrolyte-based ASC delivers a higher energy density of 51.6 Wh/kg and superior cycling stability