Full-potential calculations of the electronic and optical properties of 1T and 2H phases of TaS2 intercalated with lithium

Lithium-intercalation compounds are an important part of rechargeable lithium batteries. We have studied the effect of intercalating 1T and 2H phases of TaS2 with Li on the electronic structure and frequency dependent optical properties, using the full potential linear augmented plane wave (FPLAPW) method. We report calculations for 1T and 2H phases of LiTaS2. We find that intercalating 2H-TaS2 with Li causes opening up of an energy gap at the Fermi energy (EFEF) making it a semiconductor. This gap (0.78 eV) is indirect between the conduction band minimum (CBM) located at KΓ and the valence band maximum (VBM) located at Γ. The Li-s and Li-p bands are very broad and do not contribute much to the density of states. Our calculations show that the electronic and optical properties are influenced significantly by the location of the Li intercalate in TaS2.