Highly Conductive and Self‐Healing Polymer‐Silver Nanocomposite Hydrogel‐Based All‐in‐One Stretchable Supercapacitor

Stretchable supercapacitors offer strong potential as energy storage solutions for next‐generation stretchable electronics. However, maintaining stable and durable electrical output under various deformations, such as bending, twisting, and stretching, remains a challenge. This study presents an all‐in‐one stretchable supercapacitor that utilizes a polymer‐silver nanocomposite hydrogel as the unified base for both the electrode and electrolyte layers. Nonstoichiometric nickel oxide nanoparticles are synthesized and integrated into the polymer‐silver nanocomposite hydrogel to form the hydrogel electrode, which exhibits an elongation at break of up to 1711%, an ultimate tensile strength of 250.7 kPa, and an energy at break of 1.65 MJ m −3 . The supercapacitor device is constructed by placing the nanocomposite hydrogel electrolyte layer (swollen in a lithium chloride solution) between two hydrogel electrode layers, with an areal capacitance of 6.4 mF cm −2 at 0.5 mA cm −2 . The device demonstrates excellent self‐healing capability with self‐healing efficiencies of ≥80% for mechanical properties and 98% for electrochemical performance. These findings provide a promising avenue for next‐generation stretchable energy storage devices.