Self-healing polymer-clay nanocomposite hydrogel-based all-in-one stretchable supercapacitor

Stretchable supercapacitors are promising energy storage devices for the next generation of stretchable systems. However, having a stable and durable electrical energy output is challenging under various deformation conditions such as bending, twisting, and stretching. In this work, we report a novel all-in-one stretchable supercapacitor using a polymer-clay nanocomposite (PCN) hydrogel as the base for both the electrode and electrolyte layers. To prepare the hydrogel electrode, hybrid nanoparticles composed of multi-walled carbon nanotubes and manganese dioxide were synthesized and incorporated into the PCN hydrogel. The hydrogel electrode showed an elongation at break up to 6511 %, ultimate tensile strength of 29.2 kPa, and energy at break of 1.6 MJ m−3. The final hydrogel supercapacitor was assembled by sandwiching a PCN hydrogel electrolyte layer (containing a LiCl salt solution) between two layers of hydrogel electrode, realizing an areal capacitance of 45.6 mF cm−2 at 0.5 mA cm−2. The device also showed self-healing ability.