Modulating electrolyte solvation for high-performance aqueous zinc–sulfur batteries

Abstract

Rechargeable aqueous zinc/sulfur (Zn/S) batteries are promising candidates for large-scale energy storage applications owing to their high specific capacity and energy density with additional advantages of zinc and sulfur being abundant and cost-effective. However, practical application is impeded by the poor reversibility of the sulfur cathode and parasitic reactions at the Zn anode, limiting their capacity and cycling life. To address these challenges, an aqueous hybrid electrolyte comprising dimethylacetamide (DMA) as a high-donor number organic cosolvent and ZnI₂ as an additive was developed. The designed hybrid electrolyte helps in facile sulfur conversion and efficiently suppresses the HER and corrosion by reconstructing the solvation shell of zinc ions, thereby facilitating uniform Zn deposition. The designed Zn/S battery exhibits improved electrode reversibility with a specific capacity of 1453 mA h g⁻¹ at 0.1 A g⁻¹ and 72% capacity retention at 5 A g⁻¹ over 300 cycles. The DMA-modified electrolyte presents a novel approach for utilizing high donor-number solvents to mitigate water-induced side reactions in other aqueous metal–sulfur batteries.