Lattice matching and halogen regulation for synergistically induced large Li and Na storage by halogenated MXene V3C2Cl2.

ABSTRACT

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.