Highly flexible and adhesive poly(vinyl alcohol)/poly(acrylic amide-co-2-acrylamido-2-methylpropane sulfonic acid)/glycerin hydrogel electrolyte for stretchable and resumable supercapacitor

Adhesion and stretchable hydrogel electrolytes have emerged as an ideal candidate in the fabrication of flexible all-solid-state supercapacitor. However, the conventional hydrogel electrolyte would inevitably deteriorate or even deactivate after mechanical damage (stretching and cutting) or dehydrating. As an alternative to overcome these limitations, we designed a dynamic elastic molecular double network (DN) hydrogel electrolyte consisting of poly(vinyl alcohol) (PVA) and poly(acrylic amide-co-2-acrylamido-2-methylpropane sulfonic acid) (P(AM-AMPS)) networks. Glycerin was introduced into the PVA/P(AM-AMPS) system to enhance the inter-chain physically-crosslinked network. This DN hydrogel electrolyte exhibited remarkable stretchability (over 894%), strong adhesion (37.00 kPa to carbon materials) and high ionic conductivity (3.85 S m−1). In particular, the dynamic physically-crosslinked network endowed hydrogel electrolyte eminent mechanical tolerance. The toughness of hydrogel kept stable in 10 times 500% strain loading–unloading tensile test. Along with the CNT electrodes, a highly flexible all-solid-state supercapacitor was prepared by using our developed DN hydrogel as electrolyte. This hydrogel-based supercapacitor exhibited high capacitance (85.25 mF cm−2 at a current density of 0.5 mA cm−2). More importantly, benefiting from the unique network structure of hydrogel electrolyte, a steady bonding interface between electrode and electrolyte was constructed. Electrochemical performance of supercapacitor could be maintained in different working conditions. The capacitance of a device was stable upon stretching (200% strain) or bending (angle of 0–180°). In addition, hydrogel based supercapacitor could be resumed after dehydrating or cutting by accident. Our results provide a new slight into multifunctional all-solid-state supercapacitor preparation. We hope this hydrogel will promote the development of wearable energy storage.