Theoretical prediction of novel two-dimensional MA2Z4 family for Li/Na battery anodes

Abstract The synthesized MoSi 2 N 4 marks a new-born two-dimensional MA 2 Z 4 family. In this work, we present a comprehensive study on the MA 2 Z 4 family as anodes for Li- and Na-ion batteries (LIBs and SIBs) based on first-principle calculations. There exists a linear relationship between the ion adsorption energy E ads and the energy level of the lowest unoccupied states E LUS of MA 2 Z 4 , and a lower E LUS leads to more energetically favorable electron occupation and hence stronger adsorption. E LUS acts as a simple and useful descriptor, which allows for the straightforward prediction of ion adsorption based solely on the substrate electronic properties. Through evaluating the theoretical capacities and diffusion barriers, NbGe 2 N 4 is predicted to be the most promising candidate for LIBs while VSi 2 P 4 is better for SIBs, with maximum theoretical capacities of 547 mAh g −1 and 696 mAh g −1 and ion diffusion barriers of 0.34 eV and 0.10 eV, respectively. Moreover, NbGe 2 N 4 and VSi 2 P 4 show good phase stabilities by the analysis of their phase transformations. This study explores the application prospects of novel MA 2 Z 4 in LIBs and SIBs and provides a deep understanding of intrinsic electronic mechanisms.