Aqueous Eutectic Electrolytes Design for Advanced Rechargeable Zinc-Ion Batteries

Rechargeable aqueous zinc-ion batteries (RAZIBs) have emerged as leading candidates for next-generation large-scale energy storage systems, owing to their environmental sustainability, cost-effectiveness, and operational safety. Nevertheless, in conventional aqueous electrolytes (AEs), the rampant dendrite growth, parasitic hydrogen evolution reactions (HER), and progressive cathode dissolution in RAZIBs fundamentally constrain their practical application. Addressing these limitations through electrolyte engineering has thus become a pivotal research frontier for developing practical RAZIBs. In this context, aqueous eutectic electrolytes (AEEs) have garnered significant attention, synergistically integrating the merits of aqueous systems (e.g., high ion-conductivity) with eutectic characteristics (e.g., depressed freezing points). Despite rapid progress in AEE design, a systematic analysis of their multifunctional roles in stabilizing electrodes and enhancing low-temperature performance remains absent. This review comprehensively consolidates recent breakthroughs in AEE development, with emphasis on three synergistic mechanisms: Modulation of Zn²⁺ solvation structures; Construction of robust solid electrolyte interphase (SEI); Cryoprotectant-inspired anti-freezing strategies. Furthermore, persistent challenges such as limited voltage stability and interfacial compatibility are critically evaluated, while targeted research directions are proposed, including solvent-ligand coordination tuning and artificial SEI design, and structure-property-performance relationships are reviewed. This work is expected to provide a roadmap for accelerating the deployment of AEE-empowered RAZIBs in grid-scale applications.