A highly adhesive and mechanically robust eutectogel electrolyte for constructing stable integrated stretchable supercapacitors

Conventional stretchable supercapacitors (SSCs) typically exhibit unstable performance under deformation due to the multilayer configurations. And the current manufacturing technologies also restrict the use of zero-dimensional active materials, which results in monotonous performance. Herein, a stable integrated activated carbon-based SSC was fabricated with the aid of the developed mechanical robust and highly adhesive eutectogel electrolyte. The eutectogel was prepared via introducing two polymers (poly(vinyl alcohol) and poly(N-(2-Hydroxyethyl)acrylamide)) with significantly different relaxation rates into an ionizable supramolecular complex (namely deep eutectic solvents). The mechanical and adhesive responses of the network structure were analyzed in relation to the ratio of two polymers. The results showed that the two polymers displayed well synergy. Interestingly, due to the competitive H-bonded between components, it was found that the ionic conductivity was also promoted while the mechanical strength and adhesion strength of eutectogel were improved. Furthermore, the developed eutectogel also exhibited temperature tolerance and self-healing properties. The assembled device utilizing this eutectogel electrolyte delivers an energy density of 26.6 Wh kg −1 at 80 ℃, while maintaining its capacitance even under extreme deformation of 200% strain. After 3000 cycles of repetitive stretching from 0% to 200%, it still retained 86% of the initial capacitance. This work not only offers reasonable recommendations for designing promising electrolytes, but also an inspiring approach to construct stable integrated SSCs without being limited by electrode materials or fabrication techniques.