Electronic properties and lithium storage capacities of two-dimensional transition-metal nitride monolayers

Two-dimensional nanostructures have attracted increasing interest due to their fascinating properties and broad applications. In this study, we carry out first-principles studies on the electronic properties of MXenes and investigate their application in Lithium-ion batteries. Herein, we focus on the transition-metal nitride monolayers Mi+1Ni; where M = Ta, Ti, and V; i = 1 and 2. We find that these monolayers are metallic and most of them show non-magnetic behavior, with the exception of the anti-ferromagnetic Ti2N and ferromagnetic Ti3N2. Our caLcuLations show that Li atoms can be easiLy transported on the surfaces of the monolayers, with negLigibLe barriers as Low as 0.017 eV on Ti2N, because of Low adsorption energy and Long binding distance. We further show that these monoLayers remain metallic under full Li-intercalation and have Low open circuit voltages. In particuLar, the Ti2N monolayer shows the best performance with an open circuit voltage of 0.53 V and the highest specific capacity of 487 mA h g(-1). Our caLcuLations predict that transition-metal nitride monoLayers may be applied in Lithium ion batteries with improved performance.