Robust conductive nanocomposite hydrogels with an interpenetrating network based on polyaniline for flexible supercapacitors

Abstract Conductive polyacrylic acid/polyaniline/SiO 2 (PAA/PANI/SiO 2 ) nanocomposite hydrogels as electrolytes for a high‐performance flexible supercapacitor were prepared by combining in situ radical polymerization of anionic monomer acrylic acid, in situ sol–gel reaction of vinyltriethoxysilane (VTES), and oxidative polymerization of conductive monomer aniline (ANI). In the nanocomposite hydrogel, vinyl‐SiO 2 nanoparticles served as analogous covalent crosslinkers, while the reversible noncovalent interactions (such as hydrogen bonds, electrostatic interactions, and chain entanglements) between the PAA/SiO 2 and PANI networks acted as physical crosslinkers. The interconnected PANI and PAA/SiO 2 networks thus constructed an interpenetrating three‐dimensional network that improved the movement of electrons and ions while also enhancing the mechanical properties of the hydrogel. At a volume ratio of ANI to VTES of 50:200, the compressive strength and conductivity of PAA/PANI/SiO 2 hydrogels were as high as 1505 kPa and 4.42 S/m, respectively. Moreover, the flexible supercapacitors based on the nanocomposite hydrogel electrolyte exhibited high specific capacitance (574.7 F/g), energy density (19.6 Wh/kg), and power density (1.4 kW/kg) at a current density of 0.05 A/g. Meanwhile, these supercapacitors exhibit exceptional flexibility and mechanical stability, and can be repeatedly bent without degrading performance. This nanocomposite hydrogel has considerable potential for use in other flexible energy devices and electronics due to its excellent mechanical and electrochemical properties. Highlights Conductive nanocomposite hydrogel have good conductivity and mechanical properties. Conductive hydrogels are used as electrolytes for flexible supercapacitors. Vinyl‐SiO 2 served as analogous covalent crosslinkers for the hydrogel. Noncovalent bonds between PAA/SiO 2 and PANI acted as physical crosslinkers. Interconnected PANI and PAA/SiO 2 networks formed an interpenetrating network.