Highly Flexible and Self‐Healing Supercapacitor Enabled by Physically Crosslinking Polymer Hydrogel Electrolyte

Abstract Preparation of flexible supercapacitors with excellent mechanical properties and self‐healing properties is of great significance but still remains a challenge. A self‐healable conductive hydrogel based on poly N‐hydroxyethyl acrylamide (PHEAA) is fabricated as electrolyte for supercapacitors. The design of the physically cross‐linked dual network, and rich hydrogen bonds endow the hydrogel with robust mechanical properties and strong self‐healing ability. The hydrogel exhibited an excellent stretchability (723 %) and a high ionic conductivity (21.8 mS/cm). Specially, by in situ growth of electrode film, a non‐laminated supercapacitor is obtained with flexibility and self‐healing ability. Due to the non‐laminated structure, the supercapacitor can work stably under bending and punching. The supercapacitor possessed an areal capacitance of 253.1 mF/cm 2 and the capacitance retention was 80 % after five cutting‐healing cycles. The pseudo‐capacitance contribution of the supercapacitor after self‐healing was discussed. It is noteworthy that the supercapacitor maintains the ability to power a clock after self‐healing.