Could Borophene Be Used as a Promising Anode Material for High-Performance Lithium Ion Battery?

The rapid development of electronic products has inspired scientists to design and explore novel electrode materials with an ultrahigh rate of charging/discharging capability, such as two-dimensional (2-D) nanostructures of graphene and MoS2. In this study, another 2-D nanosheet, that is a borophene layer, has been predicted to be utilized as a promising anode material for high-performance Li ion battery based on density functional theory calculations. Our study has revealed that Li atom can combine strongly with borophene surface strongly and easily, and exist as a pure Li(+) state. A rather small energy barrier (0.007 eV) of Li diffusion leads to an ultrahigh diffusivity along an uncorrugated direction of borophene, which is estimated to be 10(4) (10(5)) times faster than that on MoS2 (graphene) at room temperature. A high Li storage capacity of 1239 mA·h/g can be achieved when Li content reaches 0.5. A low average operating voltage of 0.466 V and metallic properties result in that the borophene can be used as a possible anode material. Moreover, the properties of Li adsorption and diffusion on the borophene affected by Ag (111) substrate have been studied. It has been found that the influence of Ag (111) substrate is very weak. Li atom can still bind on the borophene with a strong binding energy of -2.648 eV. A small energy barrier of 0.033 eV can be retained for Li diffusion along the uncorrugated direction, which can give rise to a high Li diffusivity. Besides, the performances of borophene-based Na ion battery have been explored. Our results suggest that an extremely high rate capability could be expected in borophene-based Li ion battery.