Self-healable, mechanically durable and cold-resistant integrated supercapacitor enabled by dual metallic redox-mediated multiple cross-linking gel polymer electrolyte

Flexible supercapacitor is an important energy supply source for wearable electronic devices. Herein, an integrated supercapacitor with exceptional electrochemical performance is successfully constructed based on a novel dual redox-mediated double network (DN) gel polymer electrolyte (GPE). Thanks to the synergistic effect of DN structure and multiple physical interactions (hydrophobic association, hydrogen bond and ionic coordination), the polyacrylic acid/lauryl methacrylate/sodium carboxymethyl cellulose/H2SO4/CuSO4_FeSO4 GPE possesses exceptional mechanical properties and rapid self-healing ability. In addition to being ionic cross-linking agents, CuSO4_FeSO4 can also serve as carrier donors and anti-freezing agents, endowing the GPE with excellent conductivity (0.17 S/cm) and low temperature adaptability. The GPE-based integrated supercapacitor demonstrates an outstanding specific capacitance of 414.96 mF/cm2 and a high energy density of 84.21 μWh/cm2, benefiting from redox reactions of Cu2+/Cu+ and Fe2+/Fe3+ at the electrode/electrolyte interface. Due to the seamless gradient structure, the interfacial resistance is reduced and the relative slippage is overcome, resulting in splendid capacitance retention of the supercapacitor under various mechanical deformations. Moreover, the device demonstrates promising self-healing ability even at −20 °C. This work provides a novel strategy for designing and fabricating the supercapacitor with self-healing, arbitrary deformability and anti-freezing in next-generation electronic devices.