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

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.