ABSTRACT
In the subject of efforts to develop potential candidates for lithium-ion batteries (LIBs) with various kinds of compounds, HfX2 (X = S, Se, or Te) is one family of transition metal dichalcogenides (TMDs) and has been concerned. In this work, the electronic and optical properties of monolayer HfX2 were investigated theoretically to provide information about essential properties and evaluate possibility to apply in batteries using quasiparticle viewpoint and first-principle calculations. They exhibit semiconducting and semimetallic behavior for HfS2, HfSe2, and HfTe2 with strong orbital hybridization of X-(s, p x, p y, p z) and Hf-(d xy, d yz, d zx, d z 2, d x 2 - y 2) orbitals. Furthermore, these structures show the strong optical adsorption and reflective, refractive index, illustrating sensitive optical properties for optoelectronic devices. Based on geometric, electronic, and optical properties of these materials, lithium is intercalated in these systems to verify electronic characteristics for lithium batteries. After lithium intercalation, these systems reveal the sensitive translation from semiconductors to metallic structures and nonmagnetic to ferromagnetic configurations, indicating the effect of lithium-intercalated HfX2. Moreover, the strong charge transfer demonstrates the significant contribution of lithium electron and ion in compounds, as well as the strong interaction of Li-X bonds. The lithium-intercalated HfX2 promises for high conductance in electrode lithium batteries.
