Conducting polymer host–guest hydrogels with bicontinuous electron/ion transport for boosted thickness–independent supercapacitance

Abstract

The development of conducting polymer hydrogels with 3D ordering and hierarchical geometry is urgent yet challenging for the design of electrochemical/electronic systems with combined features of hydrogel structures and pseudocapacitive organic materials. Herein, a host–guest hybrid gel electrode that is composed of a polypyrrole (PPy) aerogel and its skeleton-surface-constrained Fe3+-coordinated poly(acrylic acid) (Fe-PAA) hydrogel is fabricated, which can readily work as a highly elastic and self-healable electrode for an all-gel-state supercapacitor with thickness-independent capacitive performance. An interfacial polymerization approach by restraining oxidative nucleation and promoting secondary growth reactions is presented for preparing the pseudocapacitive PPy aerogel as a host component with good elasticity. Upon an impregnation with the ionically conductive and self-healable Fe-PAA hydrogel as a guest component, the resultant PPy aerogel-hosting hydrogels (PAHH) exhibit a remarkable thickness-independent supercapacitance owing to the enhanced electron/ion transport kinetics induced by a bicontinuous electron/ion-conducting network. A proof-of-concept all-solid-state supercapacitor based on the host–guest hybrid electrodes demonstrates a remarkable remarkably high areal capacitance of 2033 mF cm−2 and extremely steady retention undergoing a 60 % compression deformation and cutting damage with high self-healing performance. The host–guest geometry design for the development of bicontinuous electron/ion conductive transport in conducting polymer-based electrodes might boost unprecedented electron and ion transport in high-mass-loading thick electrodes for smart energy storage devices.