Regulating the Zn Electrode/Electrolyte Interface Toward High Stability– Insights from the Resting Time Impact on Zn Electrode Performance

Abstract

Resting, a common procedure performed before cycling, is identified to have a significant impact on the cycle performance of acidic aqueous zinc-ion batteries (AZBs). It is demonstrated that resting duration significantly affects the Zn anode's cyclability and is closely related to the evolution of zinc hydroxide sulfate (ZHS), a byproduct formed on the Zn anode in AZBs, even without electrochemical cycling. Mechanism analysis suggests that both the uniformity and quantity of ZHS are critical factors in determining the electrode's cycling stability. Consequently, controlling the interfacial ZHS effectively enhances the cycle performance of the Zn electrode by preventing Zn corrosion and promoting uniform Zn stripping/plating during cycling. It is demonstrated that an effective hydrothermal ZHS layer can protect the Zn electrode, rendering it less susceptible to resting impacts, resulting in a long cycle life of over 3800 h at 2 mA cm⁻²−0.5 mAh cm⁻². With a 30% depth of discharge, this strategy helps to extend the cycle life to >1000 h. (4 mA cm⁻²–2 mAh cm⁻²). The findings not only highlight the importance of standardizing the resting period in evaluating the AZBs performance, but also lead to the relationship understanding among resting, ZHS evolution, and Zn electrode cyclability, further guiding strategy to improve the cycling stability of AZBs.