Surface-preferred crystal plane induced by supramolecular cyclodextrin additive for highly reversible aqueous zinc metal batteries

Recently, aqueous zinc-ion batteries (AZIBs) have received significant attention owing to the high theoretical capacity of zinc metal, high safety, and low cost. However, H2O-induced parasitic reactions and uncontrollable dendritic growth on metallic Zn anodes hinder the practical application of AZIBs. Herein, we demonstrate supramolecular alpha-cyclodextrin (alpha-CD), which is added to sulfate electrolyte solutions, to regulate the deposition of Zn ions and suppress the formation of the by-product zinc sulfate (Zn4SO4(OH)(6)center dot xH(2)O). The strong affinity of the alpha-CD additive for the surface of the Zn-metal anodes induces preferential epitaxial growth of Zn along the (002) plane, which results in achieving the improved reversibility of Zn deposition. Consequently, the addition of alpha-CD extends the lifespan of symmetric cells beyond 770 h, even at a high current density of 6 mA cm(-2) and capacity of 6 mA h cm(-2). This study highlights an innovative supramolecular approach for interface regulation of metallic Zn electrodes for advanced rechargeable aqueous batteries.

Automated summary

Recently, aqueous zinc-ion batteries (AZIBs) have gained attention for their high theoretical capacity, safety, and low cost. However, parasitic reactions and dendritic growth on zinc anodes have limited their practical application. In this study, the addition of supramolecular alpha-cyclodextrin (alpha-CD) to the electrolyte solution was found to regulate zinc ion deposition and suppress the formation of by-products. The alpha-CD additive promoted the epitaxial growth of zinc along a specific plane, leading to improved reversibility of zinc deposition and extended lifespan of the batteries.