Highly\nDeformable, Conductive Double-Network Hydrogel\nElectrolytes for Durable and Flexible Supercapacitors

Abstract

Developing flexible energy storage\ndevices with the ability to\nretain capacitance under extreme deformation is promising but remains\nchallenging. Here, we report the development of a durable supercapacitor\nwith remarkable capacitance retention under mechanical deformation\nby utilizing a physical double-network (DN) hydrogel as an electrolyte.\nThe first network is hydrophobically associating polyacrylamide cross-linked\nby nanoparticles, and the second network is Zn²⁺ cross-linked\nalginate. Through soaking such a DN hydrogel into a high concentration\nof ZnSO₄ solution, a highly deformable electrolyte with\ngood conductivity is fabricated, which also shows adhesion to diverse\nsurfaces. Directly attaching the hydrogel electrolyte to two pieces\nof an active carbon cloth facilely produces a flexible supercapacitor\nwith a high specific capacitance and theoretical energy density. Remarkable\ncapacitance retention under tension, compression, and bending is observed\nfor the supercapacitor, which can also maintain above 87% of the initial\ncapacitance after 4000 charge–discharge cycles. This study\nprovides a simple way to fabricate hydrogel electrolytes for deformable\nyet durable supercapacitors, which is expected to inspire the development\nof next-generation flexible energy storage devices.