Lattice Matching and Halogen Regulation for Synergistically Induced Uniform Zinc Electrodeposition by Halogenated Ti3C2 MXenes

Dendrite growth and low Coulombic efficiency caused by uneven diffusion and electrodeposition of Zn²⁺ ions have emerged as a barrier to exploit the Zn metal anode. In this work, we demonstrate the stoichiometric halogenated MXenes (Ti₃C₂Cl₂, Ti₃C₂Br₂, and Ti₃C₂I₂) as an artificial layer that can induce the uniform Zn deposition. The efficient redistribution effect results from the coherent heterogeneous interface reconstruction and regulated ion tiling by halogen surficial termination. The synergetic effects of high lattice matching (90%) between the adopted MXenes and Zn, as well as the positive halogen regulation, Zn²⁺ ions are guided to nucleate uniformly on the most extensive (000l) crystal plane of the MXene matrix and grow in a planar manner. In terms of Zn ion regulation, Cl termination is found to be more effective than O/F, Br, and I due to its moderate adsorption and diffusion coefficiency for Zn²⁺ ions. The Ti₃C₂Cl₂-Zn anode achieves a life extension of over 12 times (840 h at 2 mA cm^-2//1 mAh cm^-2) over that of the bare Zn anode and serves more than 9000 cycles in a battery with a Ti₃C₂I₂ cathode at a high rate of 3 A g^-1. Given the abundance of lattice parameters and terminations of MXene materials, the developed strategy is expected to be extended to other metal anode systems.