Strong conductive hybrid hydrogel electrode based on inorganic hybrid crosslinking

Polyaniline/poly(vinyl alcohol)/TiO2 (PANI/PVA/TiO2) hybrid hydrogels with improved mechanical and electrochemical properties were fabricated via in situ oxidative polymerization of aniline (ANI) and in situ synthesized TiO2 with sol–gel method. Due to the combination of hydrogen bonds and electrostatic interactions among PANI, PVA, and TiO2, this inorganic hybrid crosslinking structures enabled the PANI/PVA/TiO2 hybrid hydrogel to possess reinforced tensile/compressive strength (26.5 kPa/8.2 MPa) and unprecedented self-healing performance. Moreover, with the optimized conductive pathways in the hybrid hydrogel, its conductivity was up to 1.38 S/m, which meets the requirement of being utilized as high-performance flexible solid-state supercapacitors. At current density of 0.5 A/g, the hydrogel-based supercapacitor provided a large capacitance of 41.0–127.5 F/g and a high energy density of 0.9–2.8 Wh/kg, which were superior to other flexible supercapacitors. The easily fabricated PANI/PVA/TiO2 conducting hydrogels provides a novel strategy to prepare hydrogel electrodes for flexible energy storage devices.