Multifunctional conductive and antifreeze cellulose acetate-based zwitterionic hydrogel electrolytes for flexible foldable solid-state capacitors under extreme conditions.

This study proposes a multifunctional hydrogel electrolyte (EGZn-WSCA/PSA) with wide operating temperature, excellent stretching ability, self-healing and adhesive properties. This hydrogel electrolyte is formed by using HO and ethylene glycol (EG) as solvents, water-soluble cellulose acetate (WSCA) as a reinforcing agent and PSA (PAA (polyacrylic acid) and PSBMA ([2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl))) as the network structure, which provides excellent electrical conductivity and anti-freezing ability while maintaining good mechanical properties. The introduction of an organic solvent (ethylene glycol (EG)) largely enhances the antifreeze properties of the hydrogel electrolyte, and zinc chloride (ZnCl) can also improve the electrical conductivity of the hydrogel electrolyte. The incorporation of WSCA enhanced the mechanical properties of the hydrogel with increased tensile and compressive strength. Zwitterions can provide migration channels for ZnCl, favoring ion transport. The EGZn-WSCA/PSA hydrogel electrolyte-assembled supercapacitor has excellent electrochemical performance. It can operate stably for a long time, with a capacitance of 154.17 F/g at room temperature and 53.63 F/g even at -40 °C, which opens up a new way of thinking about the application of energy storage devices under extreme conditions.