High‐Entropy Electrolyte Driven by Multi‐Solvation Structures for Long‐Lifespan Aqueous Zinc Metal Pouch Cells

Abstract Aqueous zinc metal batteries (AZMBs) are promising candidates for grid‐scale energy storage due to their low cost and high safety. However, the poor stability and the unfavorable freezing point of aqueous electrolytes hinder their actual application. Herein, a ternary salts‐based high‐entropy electrolyte (HEE) composed of Zn 0.2 Na 0.4 Li 0.4 (ClO 4 ) 1.2 ⋅ 7H 2 O is proposed to address the above issues. The addition of perchlorate salts with different cations reduces the size of ion clusters, significantly increases the solvation structure species, and promotes the anion‐rich Zn 2+ solvation structures, resulting in an enlarged electrochemical stability window, favorable viscosity and ionic conductivity, and low freezing point. Furthermore, advanced characterization and theoretical calculations confirm that multiple types of solvation structures effectively increase the entropy of the electrolyte. As a consequence, the Zn/Zn symmetric cells in HEE can sustainably cycle for at least 1000 hours and 1500 hours under room and subzero temperatures, respectively. The Na 0.33 V 2 O 5 /Zn and polyaniline/Zn full cells can even last for 30000 and 20000 cycles without capacity decay at −20 °C, respectively. The pouch cells employing HEE deliver promising capacity and stability, even at high mass loading of active materials. This strategy of introducing multiple salts with different cations to construct a high‐entropy environment provides a facile approach for high‐performance and long‐lifespan AZMBs across a wide temperature range.