In-situ fabrication of benzoquinone crystal layer on the surface of nest-structural ionohydrogel for flexible "All-in-One" supercapattery.

Flexible energy-storage devices laid the foundation for a convenient, advanced, fossil fuel-free society. However, the fabrication of flexible energy-storage devices remains a tremendous challenge due to the intrinsic dissimilarities between electrode and electrolyte. In this study, we proposed a strategy for fabricating the flexible electrode and electrolyte entirely inside a matrix. First, we designed a nest-structural and redox-active ionohydrogel with excellent stretchability (up to 3000%) and conductivity (167.9 mS/cm) using a hydrated ionic liquid (HIL) solvent and chemical foaming strategy. The nest-structure ionohydrogel provided sufficient "highways" and "service area", and the cation in HIL facilitated the reaction, transportation, and deposition of benzoquinone. Subsequently, we in-situ fabricated a novel benzoquinone crystal-gel interface (CGI) on the surface of the ionohydrogel through electrochemical deposition of benzoquinone. Thus, we successfully achieved an integrated CGI-gel platform with a middle body as an electrolyte and the surficial redox-active CGI membrane for electrochemical energy conversion and storage. Based on the CGI-gel platform, an extreme simple and effective "stick-to-use" strategy was proposed for constructing flexible energy-storage devices and then we fabricated a series of flexible supercapatteries with high stretchability and capacitance (5222.1 mF/cm 2 at 600% strain), low self-discharge and interfacial resistance and a wearable, self-power and intelligent display. This article is protected by copyright. All rights reserved.