Exploring the potential of 2D Sc2NX2 MXene as an anode material for metal-ion (Li+, Na+, Mg2+, and Ca2+) batteries: A DFT study

2D MXene materials, renowned for their superior electrical conductivity and energy density, hold great potential as the electrodes for metal − ion batteries. Density functional theory calculations were employed for the potential of Sc₂NX₂ (X = F, Cl, S, Se, P, Si) MXenes as anode materials. Stability analysis reveals that Sc₂NF₂, Sc₂NCl₂, Sc₂NS₂, and Sc₂NSe₂ exhibit excellent dynamic, mechanical, and thermal stability, and are likely to be experimentally synthesizable. Conversely, Sc₂NP₂ and Sc₂NSi₂ are unstable and unsuitable for electrode applications. Adsorption studies of Li, Na, Mg, and Ca ions on the substrate surface show that these metal ions spontaneously and stably adsorb on the surfaces of Sc₂NS₂ and Sc₂NSe₂, whereas the poor adsorption of the ions on Sc₂NF₂ and Sc₂NCl₂ limits their use as electrode materials. Further evaluation was carried out on the electronic characteristics, migration behaviors, theoretical capacities, and OCV for Sc₂NS₂ and Sc₂NSe₂. Sc₂NS₂ achieves notable capacities of 956.96, 1913.91, and 637.98 mAh/g for Na, Mg, and Ca, while Sc2NSe2 displays capacities of 614.09, 818.79, and 409.39 mAh/g. Both materials feature small diffusion resistance and optimal OCV values. In conclusion, Sc₂NS₂ and Sc₂NSe₂ emerge as highly promising anode materials for Na, Mg, and Ca metal-ion batteries because of the remarkable stability, large capacities, and efficient ion migration properties.