A brief review on synthesis, properties and lithium-ion battery applications of borophene

Most recent exciting experimental advances introduced buckled and flat borophene materials as new members to the advancing family of two-dimensional (2D) materials. Borophene is the boron atom analog of graphene with interesting properties suitable for a wide variety of applications. Borophene (two-dimensional boron sheet) is a new type of two-dimensional material, which is electron-deficient and cannot form graphene-like structures. Instead, triangular boron lattices with hexagonal vacancies have been predicted to be stable. Recently, experimental and theoretical studies showed that the B-36 sheet has a planar C-6V structure with a central hexagonal hole, providing the first experimental evidence for the viability of atom-thin boron sheets with hexagonal vacancies, dubbed borophene. This comprehensive review deals with the investigation of optical, electronic, structural, mechanical, biomedical, and sensing properties of borophene and its applications including Li atoms adsorption and diffusion on borophene. The band structure of borophene shows highly anisotropic metallic behavior. The obtained optical properties of borophene exhibit strong anisotropy as well. The proposed flat borophene films as electrically conducive and thermally stable anode materials with ultra-high capacities of 2040 mAh/g for Li-ion batteries, which distinctly outperform not only the buckled borophene but also some other 2D materials. The combination of high optical transparency and high electrical conductivity in borophene makes it a promising candidate for the future design of transparent conductors used in photovoltaics. This study may provide a useful viewpoint with respect to the possible application of flat borophene films for the design of high capacity and lightweight advanced rechargeable ion batteries.