Stretchable and Shelf-Stable All-Polymer Supercapacitors Based on Sealed Conductive Hydrogels

The emerging stretchable supercapacitor (SSC) is the key component in stretchable electronic devices. Most of the current SSCs require elastic substrates to load electroactive materials, which limit the volumetric capacitance and stability of these SSCs. Conductive polymer-based hydrogel (CPH) has attracted much attention for developing substrate-free SSC, but most of the CPHs are limited by their low electric conductivity and poor shelf stability. Herein, we report a stretchable CPH with enhanced electric conductivity, which can be directly used to make all-polymer SSC with high specific capacitance and good shelf stability. This CPH is formed by dynamically cross-linking rigid polyaniline and soft poly(vinyl alcohol) through boronate bonds. The dynamic network structure can effectively dissipate the destructive energy during mechanical or electrochemical deformation, making this CPH strong and robust; it also helps to maximize the utilization of polyaniline, enabling this CPH with high electric conductivity and specific capacitance. This CPH can be directly used as substrate-free electrodes for making all-polymer SSC, which is sealed with a stretchable polymer bilayer film to improve the shelf stability of this SSC. The resulted SSC exhibits a specific capacitance of 516 F g(-1) and an areal capacitance of 4528 mF cm(-2), along with a high energy density of 36 Wh kg(-1), which is outstanding among CPH-based SSCs. The electrochemical properties of this SSC are well maintained upon being repeatedly stretched to 50% strain and during one-month storage in air. With high capacitance, outstanding mechanical and electrochemical stabilities, and prolonged shelf life, our all-polymer SSC is a promising power device for stretchable electronic devices.