Mechanically Interlocked Solid‐Solid Bicontinuous Phase Epoxy/Water‐In‐Salt Hydrogel Structural Electrolyte for Zinc‐Lithium Hybrid Structural Batteries

Abstract Aqueous zinc‐ion structural batteries have gained attention due to their high safety, high theoretical capacity, and strong mechanical load‐bearing properties. However, the advancement of such batteries has been restricted by their lack of a high‐voltage plateau and water side reactions, which can even lead to structural failure due to dendrite penetration. To address these limitations, a solid‐solid bicontinuous phase epoxy/water‐in‐salt hydrogel structural electrolyte (E/WHSE) is developed for zinc‐lithium hybrid structural batteries. This material effectively suppresses zinc dendrite growth, enhances electrochemical stability, and substantially improves structural integrity by mechanical interlocking. The E/WHSE maintains a relatively high ionic conductivity of 0.56 mS cm −1 and a high plateau contribution of 71.7%, while increasing the tensile strength of the epoxy membrane to 11.23 MPa by over 28.9%, thereby achieving simultaneous optimization of mechanical and electrochemical performance. Notably, the device exhibits a remarkable bending strength of 428.42 MPa and maintains stable charge–discharge performance under 300 MPa bending stress, with in situ full mechanical and electrochemical recyclability. Even in a fractured state, it continues to complete cycling, delivering nearly 88% capacity retention. These results highlight its promising potential for applications in structural energy storage and multifunctional materials.