Electrochemical intercalation of lithium ions into NbSe$_{\mathrm{2}}$ 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. One TMDC that has been studied for its charge density wave transition behavior and superconductivity is metallic NbSe$_{\mathrm{2}}$, yet it is still largely unexplored for device applications in electronics, optics, and batteries. Through this work, we demonstrate successful electrochemical intercalation of lithium ions into layered NbSe$_{\mathrm{2}}$. We present evidence of lithium intercalation as a technique capable of modifying the material properties of hexagonal NbSe$_{\mathrm{2}}$ for further study. We confirm our result through X-ray diffraction, showing a unit cell size increase in NbSe$_{\mathrm{2}}$ after intercalation from 12.57 {\AA} to 13.57 {\AA} in the ``c'' lattice dimension. Additionally, planar half-cell micro-battery devices are fabricated using ultra-thin NbSe$_{\mathrm{2}}$ from platelets to observe Li-ion intercalation through an increase in the optical transmittance of the material in the visible range. At 550 nm wavelength light, we observed an increase in the optical transmittance of the material by 26{\%} due to electrochemical intercalation.