Beyond the Chill: Emerging Electrolytes, Cathodes, and Air Electrodes for Cryogenic Aqueous Zn Batteries.

The burgeoning demand for energy storage in extreme cold environments has accelerated global research into low-temperature battery technologies. Aqueous zinc-based batteries (AZBs) emerge as a leading contender due to their intrinsic safety, low cost, and high theoretical capacity. However, their operation under cryogenic conditions is severely hindered by electrolyte freezing, sluggish ion kinetics, increased interfacial resistance, and rampant zinc dendrite growth. This review comprehensively summarizes cutting-edge research breakthroughs from the past two years aimed at overcoming these barriers through a multifaceted strategy, covering electrolyte engineering, cathode innovation, anode stabilization, and separator modification. Key advances include the rational design of advanced electrolytes-such as liquid systems (e.g., ZnCl2-based, Zn(ClO4)2-based, ZnSO4-based), along with novel suspension and gel polymer electrolytes-that disrupt hydrogen-bond networks, optimize Zn2+ solvation/desolvation, and improve interfacial kinetics. We also highlight new inorganic and organic cathode materials with tailored structures, as well as highly active air cathodes that enhance low-temperature reaction kinetics. Additionally, modified zinc anodes and functional separators with tailored ion-transport channels are discussed. Finally, we provide a summary and forward-looking perspectives on future research directions. This comprehensive survey can serve as a valuable dataset to inform machine learning approaches, ultimately guiding the accelerated development of practical low-temperature AZBs.