Mechanically Robust and Electrically Conductive Hybrid Hydrogel Electrolyte Enabled by Simultaneous Dual In Situ Sol‐Gel Technique and Free Radical Copolymerization

Abstract

Mechanically robust and ionically conductive hydrogels poly(acrylamide‐co‐2‐acrylamido‐2‐methylpropanesulfonate‐lithium)/TiO2/SiO2 (P(AM‐co‐AMPSLi)/TiO2/SiO2) with inorganic hybrid crosslinking are fabricated through dual in situ sol‐gel reaction of vinyltriethoxysilane (VTES) and tetrabutyl titanate (TBOT), and in situ radical copolymerization of acrylamide (AM), 2‐acrylamide‐2‐methylpropanesulfonate‐lithium (AMPSLi), and vinyl‐SiO2. Due to the introduction of the sulfonic acid groups and Li+ by the reaction of AMPS with Li2CO3, the conductivity of the ionic hydrogel can reach 0.19 S m−1. Vinyl‐SiO2 and nano‐TiO2 are used in this hybrid hydrogel as both multifunctional hybrid crosslinkers and fillers. The hybrid hydrogels demonstrate high tensile strength (0.11–0.33 MPa) and elongation at break (98–1867%), ultrahigh compression strength (0.28–1.36 MPa), certain fatigue resistance, self‐healing, and self‐adhesive properties, which are due to covalent bonds between TiO2 and SiO2, as well as P(AM‐co‐AMPSLi) chains and SiO2, and noncovalent bonds between TiO2 and P(AM‐co‐AMPSLi) chains, as well as the organic frameworks. Furthermore, the specific capacitance, energy density, and power density of the supercapacitors based on ionic hybrid hydrogel electrolytes are 2.88 F g−1, 0.09 Wh kg−1, and 3.07 kW kg−1 at a current density of 0.05 A g−1, respectively. Consequently, the ionic hybrid hydrogels show great promise as flexible energy storage devices.