Stable Zinc Metal Battery Development: Using Fibrous Zirconia for Rapid Surface Conduction of Zinc Ions With Modified Water Solvation Structure

Abstract The two most critical technical issues in Zn‐based batteries, dendrite formation, and hydrogen evolution reaction, can be simultaneously addressed by introducing negatively charged fibrous ZrO 2 as a separator. Electron redistribution between ZrO 2 and Zn 2+ ions renders the ZrO 2 surface a preferred adsorption site for Zn 2+ ions, making surface conduction the primary ion‐transport mode. Surface conduction enables fibrous ZrO 2 to exhibit a 6.54 times higher single‐Zn‐ion conductivity than that of conventional glass fiber, minimizing the concentration gradient of Zn 2+ and suppressing dendrite formation. Additionally, strong Zr─O─Zn bonding stabilizes the Zn 2+ ions with fewer solvated H 2 O molecules (≈2), preventing water molecules from approaching the electrode surface, as evidenced by a 58.8% decrease in the hydrogen evolution rate. Consequently, the cycling stability of a fibrous‐ZrO 2 ‐based Zn/Zn symmetric cell (3000 h at 1 mAh cm −2 and 5 mA cm −2 ) is approximately ten times greater than that of the conventional variant. Furthermore, a fibrous‐ZrO 2 ‐based Zn–I 2 full cell exhibits a notably high energy density (271.4 Wh kg −1 ) as well as a long lifespan (≈5000 cycles) at an ultrahigh current density (4 A g −1 ).