Electrochemical Intercalation of Lithium Ions into NbSe₂ Nanosheets

Transition metal dichalcogenides (TMDCs) have been known for decades to have unique properties and recently attracted broad attention for their two-dimensional (2D) characteristics. NbSe₂ is a metallic TMDC that has been studied for its charge density wave transition behavior and superconductivity but is still largely unexplored for its potential use in engineered devices with applications in areas such as electronics, optics, and batteries. Thus, we successfully demonstrate and present evidence of lithium intercalation in NbSe₂ as a technique capable of modifying the material properties of NbSe₂ for further study. We demonstrate successful intercalation of Li ions into NbSe₂ and confirm this result through X-ray diffraction, noting a unit cell size increase from 12.57 to 13.57 Å in the c lattice parameter of the NbSe₂ after intercalation. We also fabricate planar half-cell electrochemical devices using ultrathin NbSe₂ from platelets to observe evidence of Li-ion intercalation through an increase in the optical transmittance of the material in the visible range. Using 550 nm wavelength light, we observed an increase in optical transmittance of 26% during electrochemical intercalation.