Tailoring Oxygen-Depleted and Unitary TiCT Surface Terminals by Molten Salt Electrochemical Etching Enables Dendrite-Free Stable Zn Metal Anode.

Two-dimensional TiCT MXene materials, with metal-like conductivities and versatile terminals, have been considered to be promising surface modification materials for Zn-metal-based aqueous batteries (ZABs). However, the oxygen-rich and hybridized terminations caused by conventional methods limit their advantages in inhibiting zinc dendrite growth and reducing corrosion-related side reactions. Herein, -O-depleted, -Cl-terminated TiCT was precisely fabricated by the molten salt electrochemical etching of TiAlC, and controlled in situ terminal replacement from -Cl to unitary -S or -Se was achieved. The as-prepared -O-depleted and unitary-terminal TiCT as Zn anode coatings provided excellent hydrophobicity and enriched zinc-ionophilic sites, facilitating Zn horizontal transport for homogeneous deposition and effectively suppressing water-induced side reactions. The as-assembled TiCS@Zn symmetric cell achieved a cycle life of up to 4200 h at a current density and areal capacity of 2 mA cm and 1 mAh cm, respectively, with an impressive cumulative capacity of up to 7.25 Ah cm at 5 mA cm//2 mAh cm. These findings provide an effective electrochemical strategy for tailoring -O-depleted and unitary TiCT surface terminals and advancing the understanding of the role of specific TiCT surface chemistry in regulating the plating/stripping behaviors of metal ions.