Aqueous Zn-ion batteries (ZIBs) have garnered significant interest in recent years due to their potential applications in large-scale stationary energy storage. Early ZIB research has primarily focused on searching for better cathodes and understanding cathodic Zn2+ storage mechanisms. Only very recently has ZIB research shifted to the Zn anode. Here, we report on insights into the interactions between the Zn anode and aqueous Zn-salt electrolytes gained by a systematic investigation of bulk properties of electrolytes, surface properties of the reacted Zn, electrokinetics of Zn/Zn2+ redox reaction, and cycle stability of Zn/electrolyte/Zn symmetrical cells. We found that Zn metal surface, regardless of electrolyte, are always covered by a layer of Zn-containing layered double hydroxides (Zn-LDHs) upon contact with aqueous Zn-electrolytes. We show that “OH- production” pathway resulted from the dissolved oxygen in Zn-electrolytes is the root cause for the Zn-LDHs formation. The electrokinetic studies reveal that Zn/Zn(ClO4)2 interface has the highest exchange current density, while the symmetrical cell tests show that Zn(OTf)2 is the most stable electrolyte for Zn-metal anode.

Solid-state proton and hydride anion conductors are an important family of materials as electrolytes for solid state electrochemical cells such as fuel cells, batteries, sensors, and gas separation membranes. Searching...

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