Multifunctional enhanced energy density integrated supercapacitor based on self-healing redox-mediated gel polymer electrolyte

Abstract

Flexible supercapacitors have undergone rapid development, however, there is still a serious challenge in integrating multiple functions into a single supercapacitor. Therefore, higher requirements are put forward for electrolytes and assembled technology. Herein, a redox-mediated physically crosslinked double network polyacrylic acid/polyisodecyl methacrylate/K3[Fe(CN)6] gel polymer electrolyte (GPE) has been synthesized. The double network structure and reversible interactions, including hydrophobic association, hydrogen bond and ion coordination, endow the GPE with exceptional strength, toughness and self-healability. In particular, Fe2+/Fe3+ ions play a dual role as charge carriers and crosslinking agents, simultaneously increasing the electrochemical and mechanical capabilities of the GPE (3.76 S/m and 1.99 MPa, respectively). Subsequently, a flexible integrated supercapacitor has been developed through in situ polymerization of aniline on the surface of GPE. Thanks to the seamless construction and reversible redox reactions of Fe2+/Fe3+, the supercapacitor exhibits significantly enhanced capacitance and energy density (271.6 mF/cm2 and 98.1 μWh/cm2, respectively). Moreover, the supercapacitor demonstrates promising self-healability with a 99.3 % capacitance retention rate after 10 cutting/healing cycles. Due to the mutual fusion of the electrode and electrolyte layers, the outstanding electrochemical durability is obtained even under severe deformations. Overall, the redox-mediated double network GPE and the unique integrated configuration provide an effective strategy for multifunctional energy storage devices.