Ultra‐Stable Aqueous Zinc Batteries Enabled by β‐Cyclodextrin: Preferred Zinc Deposition and Suppressed Parasitic Reactions

Abstract The intrinsic zinc dendrite growth aggravated by the uneven electric field at the Zn anode surface and the water‐induced parasitic reactions have largely impeded rechargeable aqueous zinc‐ion batteries for the practical applications in large‐scale energy storage. Here, an effective strategy is proposed to manipulate Zn deposition and simultaneously prevent the generation of insulating by‐products (Zn 4 SO 4 (OH) 6 ·xH 2 O) for improved plating/stripping on Zn anodes by the addition of a nontoxic electrolyte additive, β‐cyclodextrin (β‐CD). The simulation results indicate that β‐CD molecules prefer to adsorb horizontally on Zn (002) plane, regulating the diffusion pathways and deposition sites of Zn 2+ for the preferred Zn deposition along (002) plane without dendrite formation and inhibiting the H 2 generation and the formation of Zn 4 SO 4 (OH) 6 ·xH 2 O by facilitating desolvation of [Zn(H 2 O) 6 ] 2+ . Consequently, an ultra‐long stable cycling up to 1700 h at a high current density of 4 mA cm −2 can be achieved by the addition of β‐CD, 17 times that of the pure ZnSO 4 electrolyte and the remarkable stability is also maintained under harsh test condition (40 mA cm −2 , 20 mAh cm −2 ). This study highlights the important role of β‐CD in engineering the interfacial stability during Zn plating/stripping for high‐performing aqueous batteries.