Dendrite Growth of Lithium through Separator Using In Situ Measurement Technique

In situ techniques as a clue to clarify the mechanism of lithium dendrite growth through the separator were applied. The aim of this work was to clarify the dendrite growth mechanism through the separator and to investigate and discuss the relationship between lithium intercalation into graphite and lithium deposition on the graphite surface, applying in situ and ex situ optical microscope and in situ electrochemical impedance spectroscopy. It was visually characterized the lithium dendrite growth by the ionic transfer through the separator and obtained the fundamental knowledge by in situ optical microscope. In the case of lithium deposition through the aramid coated separator (ACS), the dendrites were observed to be granular over a wide area. On the other hand, in the case of lithium deposition through the ceramic coated separator (CCS), dendrites were fibrous over a wide area by ex situ optical microscope. The superiority of ACS is related to the flatness and uniformity of the pores due to aramid resin. This result was supported by an analysis applying in situ electrochemical impedance spectroscopy.