New phases of MBenes M2B (M = Sc, Ti, and V) as high-capacity electrode materials for rechargeable magnesium ion batteries

Rechargeable magnesium ion batteries (MIBs) have attracted great interests as a prospective candidate for next generation large-scale energy storage systems owing to the low cost and high abundance of Mg resources. However, MIBs have been restricted by the lack of suitable electrode materials for a long term. Therefore, three new phases of two-dimensional transition metal borides (MBenes) including Sc2B, Ti2B and V2B are explored as electrode candidates for MIBs. All the three M2B (M = Sc, Ti, and V) with ground states of ferromagnetic configurations are proved dynamically and thermally stable by using phonon dispersions and molecular dynamics simulations. The results show that all M2B phases have ultra-high specific capacity of 3192.813 mA h/g, 3018.414 mA h/g and 2853.953 mA h/g for Mg on Sc2B, Ti2B and V2B, respectively. In addition, the M2B monolayer only undergoes a small change in lattice constant with adsorption of single layer or multilayer ions. This work not only reports three new phases of M2B with layered structure but also further provides useful information of MBenes as promising electrode candidates for high-performance metal ion batteries.