Zinc Affinity and Hydrogen Evolution Trade-Off for Homogenous Zn Deposition in Reversible Zn Ion Batteries

Zn ion batteries (ZIBs) are promising for large-scale energy storage but their practical application is plagued by inhomogeneous Zn deposition. Despite much effort, the harm of simultaneous hydrogen evolution reaction (HER) during plating to Zn deposition, has not received sufficient studies. Herein, Sn-modified Cu nanowires (Sn@CuNWs) with Sn-Cu core-shell nanostructure to achieve uniform Zn deposition by zinc affinity-HER tendency trade-off are fabricated. Confirmed by both theoretical calculation and practical characterization, the nanowires with high zinc affinity and large deposition sites facilitate Zn deposition, while the enlarged HER tendency harmful to Zn plating is inhibited by Sn nanoshell. Therefore, the Zn deposited Sn@CuNWs anode delivers a long lifespan of 800 h at 5 mA cm^-2, and the full cell exhibits a high capacity of 294.4 mAh g^-1 at 5 A g^-1 and a high capacity retention of 97.8% after 2500 cycles. This work reveals the importance of HER regulation for reversible Zn deposition, which should be noticed in further research.