Highly Ionic Conductive, Stretchable, and Tough Ionogel for Flexible Solid‐State Supercapacitor

Abstract The increasing demand for wearable electronics calls for advanced energy storage solutions that integrate high electrochemical performances and mechanical robustness. Ionogel is a promising candidate due to its stretchability combined with high ionic conductivity. However, simultaneously optimizing both the electrochemical and mechanical performance of ionogels remains a challenge. This paper reports a tough and highly ion‐conductive ionogel through ion impregnation and solvent exchange. The fabricated ionogel consists of double interpenetrating networks of long polymer chains that provide high stretchability. The polymer chains are crosslinked by hydrogen bonds that induce large energy dissipation for enhanced toughness. The resultant ionogel possesses mechanical stretchability of 26, tensile strength of 1.34 MPa, and fracture toughness of 4175 J m −2 . Meanwhile, due to the high ion concentrations and ion mobility in the gel, a high ionic conductivity of 3.18 S m −1 at room temperature is achieved. A supercapacitor of this ionogel sandwiched with porous fiber electrodes provides remarkable areal capacitance (615 mF cm −2 at 1 mA cm −2 ), energy density (341.7 µWh cm −2 at 1 mA cm −2 ), and power density (20 mW cm −2 at 10 mA cm −2 ), offering significant advantages in applications where high efficiency, compact size, and rapid energy delivery are crucial, such as flexible and wearable electronics.