Ultrafast gelation of multifunctional β-cyclodextrin based hydrogel electrolyte for self-healing supercapacitor

Abstract

The increasing attention towards flexible supercapacitors with self-healing ability can be attributed to their capacity to endure deformation and damage. However, the development of self-healing and adhesive hydrogel electrolytes, which serve as substrate materials for supercapacitors, remains a challenge. This work reports an ultrafast gelation method for fabricating multifunctional PAA-SL-CD hydrogels with ultrahigh stretchability, fast self-healing ability, superior adhesion, and high ionic conductivity (6.15 S/m). These excellent properties can be attributed to the hydrogen bonding between β-CD, the catechol groups and PAA chains, as well as metal-catechol coordination, metal-carboxyl coordination, and the unique truncated cone structure of the β-CD molecule. A flexible supercapacitor, fabricated using PAA-SL-CD hydrogel as electrolyte, demonstrates high areal specific capacitance (950 mF/cm2) and a capacitance retention rate of 76.3 % even after five cutting and healing cycles. With the well-designed adhesion of the hydrogel electrolyte, the device exhibits impressive specific capacitance retention after cyclic bending. Notably, a series supercapacitor retains the ability to power a clock for 28 min.