Stretchable, Healable, Adhesive, and Redox-Active Multifunctional Supramolecular Hydrogel-Based Flexible Supercapacitor

The next-generation portable and wearable energy-storage devices are expected to withstand distinguished mechanical strain and damage. Hence, the electrolytes with superior self-healability, outstanding stretchability, and excellent electrochemical performance are the necessary requirements for achieving advanced supercapacitors, but it still remains a huge challenge to develop the electrolytes. Herein, a novel type of multifunctional supramolecular hydrogel electrolyte (3-dimethyl (methacryloyloxyethyl)ammonium propane sulfonate (DMAPS)–poly(acrylic acid) (PAA)/H2SO4/bromamine acid sodium (BAAS)) cross-linked by reasonably designed hydrogen bonds and ionic associations is prepared by facile one-pot copolymerization. The obtained hydrogel displays a high ionic conductivity of 40 mS cm–1, a significant self-healing behavior within only 8 min, and a large stretch strain of more than 2000%. Surprisingly, it also demonstrates robust self-adhesiveness on the electrodes, which not only avoid the relative displacement and delamination between the electrolyte and electrode layers during the repeated mechanical deformation but also is convenient for achieving the lightweight and portable energy-storage devices. Furthermore, the carbon-based supercapacitor with the DMAPS–PAA/H2SO4/BAAS hydrogel electrolyte can achieve a large electrode-specific capacitance of 240 F g–1 benefited from the introduction of the BAAS redox additive. Simultaneously, the specific capacitance maintains 96 and 89% of its initial value after 400 bending/releasing cycles and 5000 charge/discharge cycles, respectively. The investigation provides a versatile strategy to design a multifunctional hydrogel electrolyte applied to promising power sources for personalized electronics.