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

The synthesized MoSi2N4 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, 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 MA(2)Z(4) in LIBs and SIBs and provides a deep understanding of intrinsic electronic mechanisms.

Automated summary

In this study, a comprehensive investigation of the MA(2)Z(4) family as anodes for LIBs and SIBs was conducted based on first-principle calculations. It was found that there is a linear relationship between the lowest unoccupied states energy level and ion adsorption energy, where lower energy level leads to stronger adsorption. Among the MA(2)Z(4) materials, NbGe2N4 was predicted as the most promising candidate for LIBs and VSi2P4 was better for SIBs, with high theoretical capacities and low ion diffusion barriers. Additionally, both NbGe2N4 and VSi2P4 demonstrated good phase stabilities. This study explores the application prospects of MA(2)Z(4) materials in LIBs and SIBs and provides insights into their intrinsic electronic mechanisms.