Conducting polymer/graphene hydrogel electrodes based aqueous smart Supercapacitors: A review and future prospects

Abstract

• Conducting polymer hydrogels as electrode are considered the most promising to fabricate flexible supercapacitors. • Three-dimensional porous network structure of hydrogel supports the diffusion of electrolyte ions. • Graphene hydrogels as electrode are stable and highly efficient. • Conducting hydrogels possess exciting future perspectives by offering niche applications in numerous fields based on their rich surface chemistry. The increasing development of flexible and wearable supercapacitors have stimulated the smart electronics industry. Conducting polymer hydrogels have been considered the most promising and viable source to fabricate flexible supercapacitors as well as to power up the flexible miniatured electronic devices. The conducting polymer hydrogels can be synthesized through numerous routes of physical and chemical linking. Conducting polymer hydrogels as electrode possess the combined features of high electrical conductivity, outstanding electrochemical characteristics, and unique three-dimensional porous morphology with swellable characteristics, ideal interaction with electrolyte, environmentally friendly, robust, and mechanical flexibility. These features make them ideal networks for the flexible supercapacitors. Conducting polymers such as polypyrrole (PPy), polyaniline (PANI), and poly (3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) are the significant contributors in the supercapacitors as electrode materials with the above-mentioned essential features. These conducting polymers in composite/hybrid with graphene hydrogel i.e., conducting hydrogels, applied as electrode materials in the highly efficient and stable flexible supercapacitors. The current modern era and the future research may focus more on the development of conducting hydrogels with controllable size, morphology, and electrochemical characteristics that would lead to the smart and flexible supercapacitors. Subsequently, these highly efficient flexible supercapacitors promote the wearable electronics, also a green, clean, and pollution free transportation. The conducting hydrogels may also reveal potential applications in other fields.