Polyacrylic acid/graphene oxide supported bimetallic CoNi electrode architecture for a wide voltage window in aqueous electrolyte supercapacitors

Abstract

The development of mechanically stable and binder-free electrode architectures with enhanced electrode/electrolyte interfacial interaction remains a major challenge for achieving high-performance aqueous supercapacitors. In this study, a polyacrylic acid/graphene oxide-supported bimetallic CoNi electrode was directly fabricated on carbon felt by radical polymerization. The hydrogel coating improved the adhesion of the active material to the current collector, while graphene oxide enhanced the electrochemically active surface area and charge transfer. The electrochemical performances of Co/GO, Ni/GO, and CoNi/GO electrodes with different Co/Ni ratios were systematically investigated. Among all compositions, the PAAc-CoNi(70-30)/GO electrode exhibited the highest capacitive performance. A symmetric supercapacitor assembled with this electrode operated at 1.4 V in 1.0 M NaOH, delivering a maximum energy density of 23.3 Wh kg-1 at 0.4 A g-1 and a maximum power density of 8400 W kg-1 at 6 A g-1.In addition, the device retained 96.75% of its initial capacitance after 5000 cycles, demonstrating excellent cycling stability. These results highlight the potential of the proposed hydrogel-assisted electrode architecture for high-performance aqueous supercapacitors.