In recent years, highly concentrated electrolytes (HCEs) have been attracting attention as electrolytes for next-generation batteries. Lithium metal is used as an anode in next-generation batteries such as lithium-sulfur batteries, and it is important to clarify the deposition and dissolution mechanisms in HCEs. In this study, the concentration profile near the anode and the coordination state surrounding lithium ions were in-situ measured by a laser interferometer and Raman spectroscopy during lithium dissolution in the Sulfolane-based HCE.