Modelling high-performing batteries with Mxenes: The case of S-functionalized two-dimensional nitride Mxene electrode

Recent upsurge in the two-dimensional (2D) materials have established their larger role on energy storage applications. To this end, Mxene represent a new paradigm extending beyond the realm of oft-explored elemental 2D materials beginning with graphene. Here in, we employed first principles modelling based on density functional theory to investigate the role of S-functionalized Nitride Mxenes as anodes for Li/Na ion batteries. To be specific, V2NS2 and Ti2NS2 have been explored with a focus on computing meaningful descriptors to quantify these 2D materials to be optimally performing electrodes. The Li/Na ion adsorption energies are found to be high (> -2 eV) on both the surfaces and associated with significant charge transfer. Interestingly, this ion intercalation can reach up to multilayers which essentially affords higher specific capacity for the substrate. Particularly, these two 2D materials (V2NS2 and Ti2NS2) have been found to be more suitable for Li-ion batteries with estimated theoretical capacities of 299.52 mAh g(-1) and 308.28 mAh g(-1) respectively. We have also probed the diffusion barriers of ion migration on these two surfaces and these are found to be ultrafast in nature. All these unique features qualify these Mxenes to be potential anode materials for rechargeable batteries and likely to draw imminent attention.