Extreme environment-adaptable and fast self-healable eutectogel triboelectric nanogenerator for energy harvesting and self-powered sensing

Hydrogel-based triboelectric nanogenerators (H-TENGs) are emerging as an appealing platform for the wearable electronics owing to their attractive mechanical flexibilities and conductive properties. However, time- and energy-consuming polymerization process of hydrogel and inevitable freezing of water within hydrogel networks at sub-zero temperature severely limit the practical applications of H-TENGs. To address the issues, we herein report a transparent, stretchable, anti-freezing, and self-healable TENG based on the ultrafast fabricated eutectogels for energy harvesting and self-powered sensors. The eutectogel electrode is initially constructed by a dynamic oxidation and coordination system composed of sulfonated lignin (SL) and Fe3+. After immersed in deep eutectic solvent (DES), the obtained eutectogels with high stretchability (~450%), transparency (93.5%) and ionic conductivity (8.70 mS cm−1) can be retained even in extreme temperature as low as − 80 °C. Notably, the eutectogel assembled TENGs (E-TENGs) show high and stable electrical output performances including open-circuit voltage of 105 V, short-circuit current of 0.5 µA, short-circuit charge of 10 nC, and power density up to 53 mW m−2. The E-TENG with a self-charging system can easily light up 20 light-emitting diodes (LEDs) and charge up capacitors to drive commercial electronics by harvesting energy. Moreover, as a proof of concept, the flexible E-TENG can serve as a self-powered biomechanical sensor to realize the real-time monitoring of various human motions, which provide a promising and versatile platform for environment adaptable hydrogel-based TENG with reliable output performance and self-healing ability.