Lattice matching and halogen regulation for synergistically induced large Li and Na storage by halogenated MXene V 3 C 2 Cl 2 .

Suffering from the formation of metal-ion dendrites and low storage capacity, MXene materials exhibit unsatisfactory performance in Li and Na storage. In this study, we demonstrate that the MXene V 3 C 2 Cl 2 structure can induce uniform Li and Na deposition. This is achieved through coherent heterogeneous interface reconstruction and regulated ion tiling by halogen surface termination. The high lattice matching (91% and 99%) between MXenes and Li/Na, along with positive Cl terminal regulation, guides Li/Na ions to nucleate uniformly on the V 3 C 2 Cl 2 MXene matrix and grow in a planar manner. Cl termination proves effective in regulating Li/Na ions due to its moderate adsorption and diffusion coefficients. Furthermore, upon adsorption onto the Cl-terminated V 3 C 2 Cl 2 monolayer, Li 4 and Na 4 clusters undergo dissociation, favoring uniform adsorption over cluster adsorption. V 3 C 2 Cl 2 MXenes exhibit impressive Li/Na storage capacities of 434.07 mA h g -1 for Li and 217.03 mA h g -1 for Na, surpassing the Li storage capacity of Ti 3 C 2 Cl 2 by three-fold and the Na storage capacity of V 2 C by 1.4 times. This study highlights the regulatory role of Cl surface terminals in dendrite formation and Li/Na ion deposition, with potential applications to other metal-ion storage electrodes.