Electrolyte Microenvironment and Alloy Interface Synergy Enables Wide-Temperature Aqueous Aluminum-Ion Batteries From −30 to 50°C

Aqueous aluminum-ion batteries (AAIBs) have attracted interest due to the high abundance, low cost, and high theoretical capacity of aluminum. However, their development is hindered by limited electrolyte stability, severe corrosion and passivation of the Al anode, and sluggish Al³⁺ diffusion kinetics, particularly under temperature extremes. Herein, an electrolyte–anode coupled strategy is developed by combining a hydrated eutectic electrolyte with an electrodeposited Al-Zn alloy anode. The optimized electrolyte, denoted as AETH30, is composed of Al(ClO₄)₃·9H₂O, ethylene glycol (EG), triethyl phosphate (TEP), and H₂O at a molar ratio of 1:6:4:30. EG and TEP reorganize the hydrogen-bond network and establish a dynamic mixed Al³⁺ solvation environment, reducing water-dominated coordination and suppressing parasitic reactions. Electrolyte-derived interfacial species improve surface stability, while the Al-Zn alloy lowers interfacial resistance and facilitates reversible plating/stripping. Benefiting from the complementary regulation of the electrolyte microenvironment and alloy-anode interface, the Al-Zn || AETH30 || PANI full cell retains 88.81 mAh g⁻¹ after 1700 cycles at 25°C. It also maintains capacities of 53.96 and 81.47 mAh g⁻¹ after 850 cycles at −30°C and 1000 cycles at 50°C, respectively. This work demonstrates an electrolyte microenvironment and alloy interface synergy strategy for durable AAIBs capable of wide-temperature operation.