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

Abstract

The synthesized MoSi2N4 marks a new-born two-dimensional MA2Z4 family. In this work, we present a comprehensive study on the MA2Z4 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 and the energy level of the lowest unoccupied states of MA2Z4, and a lower leads to more energetically favorable electron occupation and hence stronger adsorption. 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, NbGe2N4 is predicted to be the most promising candidate for LIBs while VSi2P4 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, NbGe2N4 and VSi2P4 show good phase stabilities by the analysis of their phase transformations. This study explores the application prospects of novel MA2Z4 in LIBs and SIBs and provides a deep understanding of intrinsic electronic mechanisms.