Conducting Polymer/Hydrogel Hybrid Free-Standing Electrodes for Flexible Supercapacitors Capable of Self-Sensing Working Conditions: Large-Scale Fabrication Through Facile and Low-Cost Route

Abstract

Search for energy storage devices towards sustainability, compatibility and versatility demands flexible supercapacitors capable of sensing their surrounding conditions. Here, highly electroactive polyaniline/chitosan-hydrogel hybrid films were fabricated to develop a self-sensing motor. The hybrid electrodes showed remarkable supercapacitive properties with high-rate performance while capable of sensing electrical, thermal and chemical working conditions as evinced from the chronopotentiometric responses with consumed electrical energy as the sensing parameter. A single faradaic electrochemical reaction (the reversible oxidation-reduction) is responsible for both the sensing and charge storage properties of the hybrid film, which is exploited to develop a truly integrated sensing supercapacitor without additional connectivities. As a proof-of-concept, an all-solid-state symmetric supercapacitor was fabricated which showed large capacitance (111 mF cm-2 at 0.4 mA cm-2), high energy density (13.8 µWh cm-2 at a power density of 100 µW cm-2) as well as 74% capacitance retention after 5000 charge-discharge cycles. Besides, the current sensing characteristics of the device were tested from charge-discharge responses at a constant charged state to prove the above concept. This fundamental study provides a new direction for the development of simple and compatible self-sensing motors.