Tough and self-healable hydrogels have been prepared by the multiple supramolecular interactions of clay nanosheets with dendritic polymers or in situ-formed polymer. [ 10 ] Many workers have studied ionic gels formed by the supramolecular effect of ionic liquids and block copolymers with/without SiO 2 nanofi ller, which also demonstrate the high mechanical modulus. [ 11 ] Here, we employ a mild self-initiated UV polymerization to prepare an ionic conducting polymer gel, whose non-covalent crosslinking interaction can endow the conducting gel compressive toughness and self-recovering ability.Our system consists of four components: 1-ethyl-3-methylimidazolium chloride (EMIMCl), hydroxyethyl methacrylate (HEMA), chitosan (CS) and water, whose molecular structures have been shown in Figure 1 A. At fi rst, CS and HEMA are dissolved in EMIMCl via heating and cooling process, which forms a viscous solution from the solid of EMIMCl (Figures S1a and 1C). The destroy of crystal structure of EMIMCl is the main reason to form such homogeneous solution, which is caused by the dissolution of CS and HEMA through hydrogen bond. [ 12 ] Then, tough EMIMCl gels can be formed by irradiating the asprepared homogeneous solution with UV light (Figures S1b and S2; Figure 1 D). The UV-generated Cl radicals from EMIMCl (Figure 1 B) are the initiator for the polymerization of HEMA. [ 13 ] The physical gelation of our EMIMCl gel without crosslinker should be ascribed to the hydrogen bonding interactions between the hydroxyl group in PHEMA, the amine group of CS and imidazolium group in solvent. Interesting is that our EMIMCl gel is miscible with water, which has a slightly decrease strength but a sharply increase ionic conductivity (Figure 1 E). As shown in Figure S3, water exists in the form of free water and bound water, and is relatively stable at room temperature ( Figure S4). The fi nal EMIMCl/water gel exhibits the water and pressure controlled ionic conductivity, which is suitable as an appropriate electrolyte and separator in fl exible supercapacitors. The detailed preparation, mechanism and properties are shown as followed.The EMIMCl gels can be formed by irradiating the as-prepared homogeneous solution under 45 minutes UV light with intensity of 22.4 mw/cm 2 at 365 nm. The component ratio of the conducting gel is optimized by the comprehensive evaluation of the electrochemical performances and mechanical strength. Finally, a varying amount of water was injected into the EMIMCl gel to form EMIMCl/water gels with 5 to 50 wt% (by mass) water content (Figure 1 E). If the water was added in advance, the fi nal gel could not be obtained. The EMIMCl/water gel shows high toughness when they underwent large deformations and show good strength under compression ( Figure 2 Flexible devices are a mainstream direction in modern electronics and related multidisciplinary fi elds. [ 1 ] Concerning fl exible capacitors and batteries, the current research is mainly focused on the fabrication of fl exible electrode materials; [ 2 ] however, ele...

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