Highly Deformable, Conductive Double-Network Hydrogel Electrolytes for Durable and Flexible Supercapacitors

Abstract

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

Smart Skin‐Adhesive Patches: From Design to Biomedical Applications

“…[126] Another example of a flexible and durable supercapacitor developed by Liu et al utilized a double hydrogel network. [128] The first network was polyacrylamide crosslinked by nanoparticles, while the second network was alginate crosslinked by zinc (II) ions. The double hydrogel network was inserted into two active carbon platforms, forming a supercapacitor with high specific capacitance.…”

Recent developments of polysaccharide‐based double‐network hydrogels

“…The ZHSC synchronously exhibited high gravimetric/areal energy density and electrochemical stability, and could sustain mechanical deformations at a bending angle from 0 to 180°. Liu et al 239 developed a ZHSC from Alg‐Zn 2+ /PAAm physical DN hydrogel. Due to the good ionic conductivity of the hydrogel electrolyte with abundant free ions, the ZHSC had a high ion transport rate, low charge transfer resistance as well as outstanding scan rate capability, and capacitance behavior.…”

Facile Assembly of Hybrid Micro-Supercapacitors for a Sunlight-Powered Energy Storage System

“…has become a feasible approach in the past decades. − To take full use of these renewable resources, energy conversion and storage devices have played a pivotal role. As energy storage devices, supercapacitors (SCs) have drawn intensive attention due to the traits of high power density, long life span, short charge time, high safety, and so forth. − With the prosperous developments of Internet of Things, electronic skin, and implantable medical devices, flexible micro-supercapacitors (MSCs), as micro-energy storage devices, are attracting tremendous research interest. − …”