Uniaxially oriented zinc metal negative electrodes toward spontaneous dislocation-free homoepitaxy.

Abstract

Conventional lattice orientation modulation of metal negative electrodes typically aims to expose low-surface-energy crystal planes, which, due to their high thermodynamic stability and low migration barrier, promote planar electrodeposition behavior. However, we demonstrate that a single [11 <math xmlns="http://www.w3.org/1998/Math/MathML"> <mover><mrow><mn>2</mn></mrow> <mo>¯</mo></mover> </math> 0]-oriented Zn metal negative electrode with higher surface energy can also achieve uniform Zn deposition. Advanced atomic-level transmission electron microscopy reveals the crystallographic orientation of Zn deposits along the growth direction, showing zero lattice mismatch at the epitaxial interface. The [11 <math xmlns="http://www.w3.org/1998/Math/MathML"> <mover><mrow><mn>2</mn></mrow> <mo>¯</mo></mover> </math> 0]-oriented Zn electrode shows high reversibility over 4000 cycles in Zn| |Cu cells at 40.0 mA/cm² and 4.0 mAh/cm² and enhanced cycling stability over 2600 cycles with 94.7% capacity retention in Zn| |NH₄V₄O₁₀ cells at 2.0 A/g. This concept is further expanded to other Zn metal negative electrodes with any single lattice orientation, with growth rates and grain boundary (GB) characteristics elucidated through simulated calculations and crystallographic characterizations. Grains within a single-oriented metal negative electrode exhibit uniform growth rates, superior GB stability, and an ordered atomic arrangement, promoting spontaneous dislocation-free homoepitaxy. Our study deepens the understanding of lattice modulation and provides valuable insights for engineering other high-reversibility metal negative electrodes.