A first-principle study of FeB6 monolayer as a potential anode material for Li-ion and Na-ion batteries

Two-dimensional (2D) graphene-like hexagonal borophene sheet (HBS) is a kinetically unstable configuration since the electrons of π-valence orbitals of HBS are less than those of graphene. Inspired by the planar hexacoordinate wheel-type Fe©B6H6, we theoretically designed a novel 2D material FeB6 where the HBS can be stabilized by Fe atoms located at the center of partial boron rings. Moreover, we also investigated the possibility of using FeB6 monolayer as a potential anode for Li-ion batteries (LIBs) and Na-ion batteries (NIBs). Our calculations showed that FeB6 monolayer had strong adsorption energies (2.89 eV for Li and 2.39 eV for Na), low diffusion barriers (0.24 eV for Li and 0.10 eV for Na) and high theoretical specific capacities (991 mAh/g for Li and 622 mAh/g for Na), which indicates that FeB6 monolayer can be a potential anode material for LIBs/NIBs.