Utilizing carboxymethyl cellulose sodium/sodium lignosulfonate hydrogel to build efficient electrolyte/electrode...

Although hydrogel electrolytes have attracted much attention in flexible supercapacitors, the interfacial contact between the electrolyte and electrode is a key factor restricting the development of supercapacitors. In this work, we constructed a hydrogel supercapacitor by endowing the hydrogel electrolyte with excellent adhesion properties and adopting an interfacial integration strategy, which effectively improves the interfacial contact problem. A multifunctional PC₄L hydrogel was successfully prepared with excellent tensile properties (1976 %) and self-healing ability through the semi-interpenetrating network formed by carboxymethyl cellulose sodium and polyacrylamide chains, as well as multiple physical interactions. Meanwhile, the catechol groups in the hydrogel conferred strong adhesion. Subsequently, a flexible integrated supercapacitor was successfully prepared through in situ polymerization of polypyrrole/ammonium aurintricarboxylate/sodium lignosulfonate composite electrode materials on the PC₄L hydrogel. The supercapacitor exhibited a high specific capacitance of 624.36 mF/cm² at 1 mA/cm². Due to its strong adhesion, the supercapacitor demonstrated excellent stability under severe deformations, without delamination or displacement between the electrolyte and electrode, thereby maintaining excellent capacitance retention. The supercapacitor exhibits excellent self-healing performance with 81.4 % capacitance retention even after 5 cut-and-heal cycles. This flexible supercapacitor with stable electrochemical properties shows promising applications in wearable electronic devices.