Lattice matching and halogen regulation for synergistically induced large Li and Na storage by halogenated MXene...

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 V₃C₂Cl₂ 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 V₃C₂Cl₂ 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 V₃C₂Cl₂ monolayer, Li₄ and Na₄ clusters undergo dissociation, favoring uniform adsorption over cluster adsorption. V₃C₂Cl₂ 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 Ti₃C₂Cl₂ by three-fold and the Na storage capacity of V₂C 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.