Dual‐Salt Chaotropic Eutectic Electrolyte for Enhancing Low‐Temperature Zinc‐Ion Batteries

Abstract

Abstract Aqueous zinc‐ion batteries (ZIBs) exhibit severe performance degradation at low temperatures primarily due to the freezing of water. To mitigate this issue, we engineered a dual‐salt super‐chaotropic eutectic electrolyte that exploits the strong Hofmeister effect of zinc salts to disrupt the ordered hydrogen‐bonding network of the electrolyte, significantly lowering its freezing point. The electrolyte, formulated with Zn(ClO 4 ) 2 ·6H 2 O, NaClO 4 ·H 2 O, and acetamide, leverages the strong chaotropic properties of ClO 4 − ions to dismantle the hydrogen bonding network of water molecules, realizing an ultra‐low freezing point of −75.9 °C. Additionally, the electrolyte minimizes water activity, suppresses the hydrogen evolution reaction, and mitigates corrosion through the robust coordination among ClO 4 − , acetamide, and Zn 2+ ions, enabling uniform and compact Zn deposition. The Zn||sodium vanadium phosphate (NVP) battery demonstrates higher redox potential, exceptional low‐temperature cycling performance, achieving over 5500 cycles at −20 °C with 81.2% capacity retention and nearly 100% Coulombic efficiency. Furthermore, the pouch cell retains 94.8% of its capacity after 250 cycles at −20 °C. This innovative chaotropic eutectic electrolyte provides a promising pathway for advancing low‐temperature ZIBs with extended operational lifespans.