Highly Stretchable and Compressible Self‐Healing P(AA‐co‐AAm)/CoCl₂ Hydrogel Electrolyte for Flexible Supercapacitors

Abstract

We report a novel tough self‐healing electrolyte on the basis of poly (acrylic acid‐co‐acrylamide) cross‐linked by divalent cobalt ions (Co2+) (P(AA‐co‐AAm)/CoCl2). Intermolecular and intramolecular hydrogen bonding work together with the metal‐coordination between Co2+ and carboxylic ions to form a hydrogel, which can resist various deformations. The hydrogel electrolyte exhibits excellent mechanical performance (elongation at break >1200 %, compressive stress >600 kPa and compressibility >90 %). The established supercapacitor based on P(AA‐co‐AAm)/CoCl2 can hold its capacitance even after bending, twisting, compressing and self‐healing. Moreover, it retains 90 % capacitance after 5000 cycles. Our electrolyte shows great prospects in manufacture of intelligent flexible equipment.

Highly Strong and Tough Double‐Crosslinked Hydrogel Electrolyte for Flexible Supercapacitors

“…It was clearly shown that the Li + ion conduction rate of DC‐GPE (41.2 mS cm −1 ) was more than 3 times higher than that of LiClO 4 solution electrolyte (12.3 mS cm −1 ) at room temperature. Meaningfully, this result is well beyond our previously reported HA‐GPE (31.1 mS cm −1 ) and other single cross‐linked P(AA‐AAM)/CoCl 2 networks hydrogel electrolyte (17.2 mS cm −1 ) reported by tang . The 3D network structure endows the hydrogel with outstanding mechanical properties and excellent water/ liquid electrolyte retention performance.…”

“…Meaningfully, this result is well beyond our previously reported HA-GPE (31.1 mS cm À 1 ) and other single cross-linked P(AA-AAM)/CoCl 2 networks hydrogel electrolyte (17.2 mS cm À 1 ) reported by tang. [16,21] The 3D network structure endows the hydrogel with outstanding mechanical properties and excellent water/ liquid electrolyte retention performance. Besides, this porous structure may also provide a good channel for ion transport.…”

“…The gel exhibited a breaking strength of 350 kPa and an elongation at break of 380 %. Tang and co‐workers reported a poly (acrylic acid‐co‐acrylamide) cross‐linked by Co 2+ hydrogel electrolyte with a tensile strength of 550 kPa and an elongation at break of 900 % . Dai prepared a polyacrylamide−chitosan‐based Water‐in‐salt electrolytes with high ionic conductivity (51.3 mS cm −1 ) and operating voltage (2.6 V) and excellent flexibility and self‐healing ability .…”

“…Tang and co-workers reported a poly (acrylic acid-co-acrylamide) cross-linked by Co 2 + hydrogel electrolyte with a tensile strength of 550 kPa and an elongation at break of 900 %. [16] Dai prepared a polyacrylamideÀ chitosan-based Water-in-salt electrolytes with high ionic conductivity (51.3 mS cm À 1 ) and operating voltage (2.6 V) and excellent flexibility and self-healing ability. [17] Ayhan and co-workers prepared hydrogel electrolytes with excellent electrochemical properties by introducing ammonium molybdate into PAMPS and poly (vinylphosphonic acid) (PVPA).…”

Self‐Healing Materials for Energy‐Storage Devices

“…Zhang and co‐workers [ 171 ] fabricated a physically crosslinked, self‐healing poly (acrylic acid‐ co ‐stearyl methacrylate)/Fe 3+ hydrogel electrolyte for nanowire PANI flexible SCs. Tang and co‐workers [ 177 ] reported the stretchable and compressible self‐healing poly (acrylic acid‐ co ‐acrylamide)/CoCl 2 hydrogel electrolyte for flexible SC. In the case of electrostatic interactions between metal ions and carboxyl groups, the electrochemical stability of metal ions plays an important role in the selectivity of ESDs.…”