Tailoring aqueous electrolytes for low-temperature applications: from fundamentals to practical solutions

Aqueous batteries are promising candidates for grid-scale energy storage owing to their inherent safety and environmental sustainability; however, their low-temperature performance is hindered by electrolyte freezing and sluggish reaction kinetics. Electrolyte regulation has emerged as a key strategy to enable their operation under low-temperature conditions. This review first examines two fundamental mechanisms—hydrogen bond network and solvation structure evolution—which govern the thermodynamic and kinetic behavior of electrolytes at low temperatures. Building on these insights, we propose targeted electrolyte modifications and systematically summarize optimization strategies, including anion regulation, additives, co-solvents, eutectic electrolytes, salt selection, high-entropy system design, and novel solvation sheath engineering. Finally, we discuss current challenges and future research directions to advance low-temperature aqueous batteries through electrolyte innovation.