Superior environmentally friendly stretchable supercapacitor based on nitrogen-doped graphene/hydrogel and single-walled carbon nanotubes

Lightweight and flexible supercapacitors with high volumetric capacitance are vitally required for wearable and portable energy storage devices. We propose an eco-friendly, simple-to-fabricate high performance supercapacitor, which consists of a solid state material based on nitrogen-doped graphene flake electrodes distributed in the NaCl-containing hydrogel electrolyte, achieving a large surface area interface. Stretchability is achieved by sandwiching this structure between two single-walled carbon nanotube film current collectors. The as-prepared quasi-solid material exhibits outstanding volumetric capacitive performance, high energy density and power density values, attaining corresponding values of 806 F cm⁻³, 112 mW h cm⁻³ and 294 W cm⁻³ at 0.3 A g⁻¹. This superior capacitive behavior is due to the excellent network comprising NaCl-containing hydrogel, N-Graphene powder and carbon nanotube film, offering new strategy for developing of sustainable high-performance supercapacitors.