Hydroxylamine hydrochloride as a multifunctional electrolyte additive for dendrite-free Zn deposition in aqueous Zn-ion batteries.

Abstract

Aqueous zinc-ion batteries (AZIBs) are attractive for large-scale energy storage because of their intrinsic safety and low cost. However, the practical utilization of AZIBs is limited by dendrite growth, hydrogen evolution, and interfacial corrosion. Here, hydroxylamine hydrochloride (HH) is introduced as a multifunctional electrolyte additive to regulate the Zn/electrolyte interface and Zn2+ transport. The electrolyte micro-environment can be optimized by HH additive with polar N- and O-based sites that interact with Zn ions and alter interfacial adsorption on the Zn surface. Electrochemical measurements have demonstrated the uniform Zn nucleation enhancement and suppressed hydrogen evolution and corrosion together with improved interfacial kinetics. Compared to pristine electrolyte, the Zn2+ transference number increases from 0.23 to 0.44, while the apparent interfacial desolvation activation energy decreases from 36.86 to 28.16 kJ mol-1. Consequently, symmetric Zn cells using HH-ZSO can stably cycle for more than 500 h at 5 mA cm-2 and 3 mAh cm-2, and asymmetric cells deliver an average coulombic efficiency of 99.67%. The corresponding full-cell tests also show improved cycling performance and slow capacity decay. These results establish HH as a simple molecular-scale electrolyte modifier for stabilizing aqueous Zn metal anodes.

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