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

Abstract

ABSTRACT Traditional aluminum (Al) electrolytes are limited by the strong corrosivity and monovalent carriers ( e.g ., AlCl 4 – and Al 2 Cl 7 – ), 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 Al 3+ 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 Al 3+ 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).