Recent Progress in Aqueous Alkali-metal-ion batteries at low temperatures

Aqueous alkali-metal-ion batteries are a popular frontier research area, expected to apply for large-scale energy storage due to their high safety, low cost, and environmental friendliness. Depending on diversified social development, batteries ought to function in various ambient, including polar regions and high-altitude locales. Delivering excellent electrochemical performance at low temperatures is crucial to develop aqueous alkali-metal-ion batteries. This review summarizes the representative research progress in the field of aqueous low-temperature alkali-metal-ion batteries in recent years,based on the subjects of electrolyte, electrode, and interface. Firstly, we discussed the challenges of aqueous alkali-metal-ion batteries operated at low temperatures and the corresponding failure mechanisms. At subzero temperatures, aqueous alkali-metal-ion batteries couldn't work or exhibit little capacity, arising from the frozen electrolytes, electrode materials with slow kinetics, and huge interface impedances, which seriously limits their wide application in low-temperature conditions. Then, combined with the latest research work, various strategies have been investigated to improve the electrochemical performance of batteries at low temperatures. To date, the strategies for reducing the freezing point of electrolytes have primarily focused on breaking H-bonds between free water molecules by increasing salt concentration, adding organic/inorganic additives, and using hydrogel as electrolytes. In terms of electrodes, the related studies have concentrated on regulating the structure and morphology of electrodes, introducing the dual ion battery mechanism, and using organic materials and Zn electrodes to alleviate the slow ion dynamics of electrodes. In addition, adding appropriate organic solvents that can generate protective layers with low interface impedance on the electrode surface in the electrolyte can also improve the low-temperature performance of aqueous alkali-metal-ion batteries. Finally, we evaluated multi-dimensionally all strategies, expected to provide a comprehensive reference and point out the direction for the further improvement and practical application of the aqueous alkali-metal-ion batteries at low temperatures.