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.