Fast Dynamic Re‐Equilibration of Chloroaluminate Speciation Enables a Stable Electrode‐Electrolyte Interface in Aluminum Ion Batteries

ABSTRACT

The sluggish dynamic equilibration of ions in ionic liquid electrolytes, particularly under high viscosity conditions, originates from strong interionic interactions and inefficient utilization of charge carrier species. Here, we present a strategic electrolyte design that reconfigures the interionic interaction network and accelerates the dynamic equilibration of charge carriers in AlCl ₃ /EMIC ionic liquid electrolyte. By incorporating an optimized moderator with low polarity and small molecular size, the dynamic redistribution and re‐equilibration of charge carriers during cycling are significantly accelerated, while the continuous depletion of effective charge carriers is suppressed. Guided by this principle, the dichloroethane‐enabled electrolyte exhibits rapid chloroaluminate equilibration and improved electrode‐electrolyte stability. In situ Raman spectroscopy confirms that the moderator promotes reversible AlCl ₄ ⁻ /Al ₂ Cl ₇ ⁻ conversion. As a result, the reorganized AlCl ₃ /EMIC electrolyte suppresses dendrite growth and achieves unprecedented Al anode stability in symmetric cells. Matched with flake graphite cathodes, the full battery capacity increased by 120.7% from 92 to 203 mAh g ⁻¹ at 200 mA g ⁻¹ after 7000 cycles. This work establishes a dynamic speciation regulation principle for designing ionic liquid electrolytes with fast ion equilibration and provides a pathway toward long‐life aluminum‐ion batteries.