Gelatin-based zwitterionic self-adhesive, self-healing hydrogel electrolyte for flexible zinc-ion hybrid...

Most hydrogel electrolytes (HEs) reported to date suffer from issues such as interfacial incompatibility, excessively high modulus, poor performance in extreme environments, high cost, and toxic residues. This study aims to prepare low-cost HEs with self-adhesive, self-healing, stretchable, and compressive properties for flexible zinc-ion hybrid supercapacitors (ZIHSCs). This system utilises gelatin and methacryloyl-modified gelatin (GelMA) as the scaffold, with SBMA as the modifier, to construct a triple dynamic network via a one-pot method. This network is characterized by the synergistic interactions of hydrogen bonding, electrostatic interactions, and ionic coordination. Compared to conventional hydrogels based solely on GelMA (which rely on photopolymerization and exhibit poor adhesion and self-healing properties) or [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (SBMA) (which lack mechanical toughness), this system combines excellent self-adhesion , self-healing capability (at 50 °C), high tensile strain (ultimate tensile stress of 0.75 MPa and strain of 182%), fatigue resistance, high ionic conductivity (0.045 S/m), and multifunctional sensing, while also being cost-effective and environmentally friendly. The prepared hydrogels were characterized using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM), with the crosslinking mechanism analyzed through mechanical property tests. Furthermore, the assembled ZIHSCs achieved a discharge capacity of 99.9 mAh g^-1 and an energy density of 100 mWh g^-1, with excellent cycling stability over 2500 h in constant-current charge-discharge tests. Overall, this study provides new insights into the simple and efficient fabrication of environmentally friendly multifunctional flexible sensors and ZIHSCs.