High-entropy electrolytes with high disordered solvation structures for ultra-stable zinc metal anodes

Abstract

Aqueous zinc-ion batteries (ZIBs) are playing an increasingly important role in the field of energy storage owing to their low cost, high safety, and environmental friendliness. However, their practical applications are still handicapped by severe dendrite formation and side reactions (e.g., hydrogen evolution reaction and corrosion) on the zinc anodes. Herein, a low-concentration high-entropy (HE) electrolyte strategy is proposed to achieve high reversibility and ultra-durable zinc metal anode. Specifically, this HE electrolyte features multiple anions participating in coordination and highly disordered solvation shells, which would disrupt the intrinsic H-bond network between water molecules and suppress interfacial side reactions. Moreover, these diversified weakly solvated structures can lower the solvation energy of Zn²⁺ solvation configurations and enhance zinc ion diffusion kinetics, thereby promoting uniform Zn deposition and electrode interface stability. Consequently, Zn Zn symmetric cells exhibit over 2,000 hours of cycling stability, and Zn Cu asymmetric cells achieve a high average Coulombic efficiency of 99.9 % over 500 cycles. Furthermore, the Zn PANI full cell with the optimized HE-50 mM electrolyte delivers a high specific capacity of 110.7 mAh g⁻¹ over 2,000 cycles at 0.5 A g⁻¹ and a capacity retention of 70.4 % at 15 A g⁻¹ after 10,000 cycles. Remarkably, even at a low temperature of −20 °C, the Zn PANI full cells equipped with HE-50 mM electrolyte still demonstrate long-term cycling stability over 600 cycles with a high-capacity retention of 93.5 %. This research provides a promising strategy for the design of aqueous electrolytes, aiding in the development of low-cost, high-safety, and high-performance aqueous batteries.