A First-Principles study of monolayer and heterostructure antimonene as potential anode materials for Magnesium-ion batteries

The development of magnesium-ion batteries requires anode materials with high capacity and fast kinetics. Based on first-principles calculations, outstanding magnesium capacities have been found for antimonene and an antimonene/graphene heterostructure. The results show that Mg atoms can adsorb on the surface of antimonene, and the most stable position is the site immediately above the center of the buckled honeycomb six-membered Sb ring. Compared with the heterostructure of antimonene, the monolayer has a relatively large binding energy for Mg atoms (−0.72 eV for antimonene and −0.70 eV for the heterostructure). Furthermore, we reveal that Mg ions diffuse more easily on the surface of the heterostructure than on the surface of the antimonene monolayer, and the lowest diffusion barrier is 45 meV. More importantly, the nanostructures based on antimonene have relatively large capacities of 735 mA h/g (as Mg1.67Sb) and 615 mA h/g (as Mg1.78SbC2.78). We expect that all these results can help clarify the mechanism of Mg storage in low-dimensional antimony materials and shed light on the design of magnesium-ion batteries.