Customizing ion transport and deposition with hybrid hydrogel electrolyte toward safety and stability flexible quasi-solid Zn metal batteries

Aqueous zinc-ion batteries (AZIBs) are susceptible to interface dendrite problems resulting from the high-water content and the unstable solid electrolyte interface (SEI), leading to suboptimal cycle stability. Here, a hybrid hydrogel electrolyte for AZIBs was designed through the synergistic regulation of chains and aprotic polar solvent (APS). By the polar groups in the chain and the solvation ability of the additives, the Zn 2+ ions solvation structure was synergistically optimized, thereby increasing the Zn 2+ ions transfer number (0.79) and achieving high ionic conductivity (28.04 mS cm −1 ) of PS-TG4 5% electrolyte. Moreover, the additives enhance the interfacial interaction of the hydrogel matrix, thereby forming a stable hybrid SEI (ZnO, ZnS and ZnCO 3 ). This helps the reaction rate of the interface and regulates zinc deposition/dissolution over time. Ultimately, the effective inhibition of side reactions and hydrogen evolution reaction (HER) enables the assembled AZIBs to possess excellent safety (using under physical damage) and long-term cycling stability (capacity retention of 75.6% after over 2700 cycles). This research provides valuable inspiration for designing hydrogel electrolytes with high ionic mobility, toughness and stability, with great potential for use in energy storage applications.