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 α-cyclodextrin (α-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·xH₂O). The strong affinity of the α-CD additive for the surface of the Zn-metal anodes induces preferential epitaxial growth of Zn along the (0 0 2) plane, which results in achieving the improved reversibility of Zn deposition. Consequently, the addition of α-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.