In the recent years, all-solid-state batteries have attracted much attention as they are safer in terms of flammability compared to liquid electrolyte systems. There are polymer, oxidic, and sulfidic solid electrolytes with advantages and disadvantages. One major advantage of sulfidic electrolytes is their high ionic conductivity at room temperature which is even comparable with that of liquid electrolytes. Another feature is the possible usability of lithium anodes in this system which leads to very high energy density. One major challenge of the lithium metal anode is the formation and growth of lithium dendrites which results in short circuits. A lot of research is done to prevent dendrite growth but more research is needed to understand the actual dendrite growth mechanism [1]. In our work we analyzed the reasons for increase of overpotentials that is very likely related to lithium dendrite growth in symmetric lithium metal cells with solid electrolyte Li6PS5Cl. In a three-electrode set up, the interface of a lithium symmetric cell is analyzed during stripping and plating with electrochemical impedance spectroscopy. The changes of the resistance contributions are discussed in terms of possible major mechanisms that are involved in lithium dendrite growth. Furthermore, the plating behavior of lithium is investigated which gives insight into possible onset for lithium dendrite growth. Reference s : [1] Xin-Bing Cheng, Rui Zhang, Chen-Zi Zhao, and Qiang Zhang, Toward Safe Lithium Metal Anode in Rechargeable Batteries: A Review, Chem. Rev. 2017, 117, 10403−10473.