Oriented‐Electrochemical Etching of Zn Crystal Edges in Deep Eutectic Solvent for Enhancing Stability and Reversibility of Zn Anodes

Abstract

AbstractMetal Zn anode encounters uncontrolled dendrite growth, resulting in poor cycling stability and low coulombic efficiency (CE). Herein, a novel approach for oriented‐electrochemical etching of Zn (ECE‐Zn) in deep eutectic solvent (DES) is presented to adjust the interface concentration and electric fields, effectively mitigating intractable issues. The oriented etches off the crystal edges between the (002), (100), and (101) principal crystal planes of commercial Zn foil, subsequently etches the (100) and (101) crystal planes, resulting in the formation well‐organized Zn columns. Comprehensive experimental investigations and theoretical analyses reveal that Zn ions directionally nucleate and grow between Zn columns, enabling epitaxial growth at the (002) crystal plane. The ECE‐Zn‐2 anodes demonstrate remarkable stability, along with low nucleation and polarization voltages. Specifically, the symmetric ECE‐Zn‐2 cells show sustained operation for 5400 h, and long‐term 10 000 cycles at 40 mA cm−2. More significantly, the asymmetric cells exhibit an average CE as high as 99.92% over 6000 cycles at 5.0 mA cm−2. When assembled with a V2O5 cathode, a high retention of 81.5% can be maintained even under severe condition (N/P ratio of 7.35). This strategy of oriented‐electrochemical etching for commercial Zn opens up a new pathway for dendrite‐free Zn metal anode.