Low‐Hysteresis and Tough Ionohydrogels Well‐Balanced by Water

Abstract Low‐hysteresis merits in polymeric gel materials can significantly enhance their operational reliability and service lifetime in emerging applications such as smart wearable devices. However, fabricating gel materials with low hysteresis and high toughness remains challenging due to their intrinsic contradictory attributes, particularly in ionic liquid (IL)‐based systems. Herein, a water‐mediated polymer network reorganization strategy is presented for developing tough and low hysteresis ionohydrogels (IHGs) containing ILs, where the synergistic effect between covalent crosslinking and dynamic interfacial lubrication governs their exceptional performance. Water can act as a lubricating mediator to moderately attenuate interactions between ILs and polymer chains, thereby enabling the formation of dynamically adaptive networks that facilitate chain mobility and stress redistribution. Therefore, the IHGs fabricated through water content modulation achieve a well‐balanced combination of high toughness (2.2 MJ m −3 ) and low hysteresis (8.1% at 400% strain). Meanwhile, the prepared IHGs demonstrate superior comprehensive performance, including high stretchability, excellent tensile strength, superior electrical conductivity, good biocompatibility, and transparency. Finally, the IHGs can function as high‐performance wearable sensors and biocompatible epidermal electrodes, enabling real‐time health monitoring and acquisition of high‐fidelity electrophysiological signals. The simple strategy overcomes the traditional trade‐offs of low hysteresis and high toughness, demonstrating exceptional potential in real‐life scenarios.