Promoting Zn Interfacial Transfer and (002)-Textured Zn Deposition via a Thin AlF Layer for Stable Zn Electrode in Aqueous Battery.

Suppressing zinc (Zn) dendrite and corrosion is a crucial challenge for aqueous Zn batteries (AZBs). An aluminum (Al) protective layer can regulate Zn deposition by enhancing Zn interfacial transfer through the Zn-Al alloy, which however suffers from the sensitive passivation by AlO. While employing a thick Al layer may preserve the Zn protective ability despite the surface passivation, it inevitably compromises the energy density of the battery accordingly. Herein, a thin AlF layer (<1 µm) is proposed to address these issues, where the strong Al─F bonds endow the thin layer with a high stability against the surface passivation. Meanwhile promoted Zn interfacial transfer on the AlF surface is revealed by experimental and modeling approaches. Furthermore, the AlF layer favors a (002)-textured Zn deposition owing to the low interfacial energy between Zn(002)/AlF(002) facets, leading to uniform and corrosion-resistant Zn deposits. Consequently, a high coulombic efficiency of 99.9% is achieved for Zn cycling at 2 mA cm over 8000 cycles, and the Zn‖I full cell achieves a high capacity retention of 92.1% after 7500 cycles. This work provides valuable insights into the construction of thin protective layer for stable Zn electrode in AZBs.