GO-induced in-situ polymerization of aniline on hydrogel electrolyte into one-body flexible supercapacitor for motion-sensing application

Flexible supercapacitors often face challenges due to the dissociation between electrodes and hydrogel electrolytes. To address this issue and enhance performance, we propose an in-situ growth strategy for integrating electrode materials with hydrogel electrolytes into a unified supercapacitor structure. In this work, we demonstrate the in-situ polymerization of aniline under slow reaction kinetics on a polyvinyl acetate/sodium alginate-based hydrogel modified with GO. The GO plays a dual role: (1) its π-π interaction with the aromatic rings of PANI and hydrogen bonding with amino groups facilitate the formation of a continuous porous PANI structure, while (2) the controlled polymerization kinetics improve crystallinity. The resulting PANI-LT-GO device delivers an optimized areal specific capacitance of 102.51 mF cm -2 at 0.3 mA cm -2 , with excellent mechanical stability, rate capability, and cycling performance—showing no degradation after deformation. Furthermore, by embedding a piezoelectric PVDF-TrFE(poly(vinylidene fluoride-trifluoroethylene)) thin film within the hydrogel electrolyte, the flexible device achieves self-charging functionality and can serve as a stress sensor for human motion monitoring. These properties, including biocompatibility and the ability to generate voltage, highlight the promise of device for enabling self-powered wearable electronics.