Reactivity-Controlled Aluminum (III)-Based Electrolyte Enables Year-Long Stable Metal Anodes

Traditional aluminum (Al) electrolytes are limited by the strong corrosivity and monovalent carriers (e.g., AlCl₄ ^- and Al₂Cl₇ ^-), preventing rechargeable Al-metal batteries from long-cycling stability and high energy density. Electrolytes composed of simple salts and organic solvents offer non-corrosive properties and trivalent Al³⁺ carriers, but their practical application is hampered by passivation issues and sluggish de-solvation/diffusion kinetics. These two types of electrolytes exhibit fundamentally different reactivity modes: corrosion-dominated destructive reactivity versus passivation-dominated blocking reactivity. Here, we propose a reactivity-control strategy that leverages the controlled corrosivity of organochlorine co-solvents to rejuvenate passivation-dominated simple-salt-based electrolyte systems. These reactivity-controlled electrolytes not only support trivalent Al³⁺ carriers but also avoid the extreme reactivity of passivation or corrosion. Consequently, they enable Al plating/stripping at a low overpotential of about 0.5 V (vs. over 5.0 V for blank) and achieve an ultra-long cycling lifespan exceeding 8760 h (365 days).