EIS was applied to monitor the WE interface evolution. At high frequencies, the uncompensated resistance is almost identical to the measurements taken before and after the CP procedure (Figure ). Despite the variability in the wetted area, the high-frequency areal resistance (corrected by the tip area) is highly reproducible (Figure ). At lower frequencies, the difference is more pronounced, with an extra semicircle appearing in the measurement taken after the CP, which could correspond to the charge transfer resistance and electrical double layer and indicate the formation of SEI (Figure ). The lowfrequency resistance is less reproducible, with lower resistances observed for the spots with leakage, i.e. the larger wetted area (Figure ). This discrepancy could be attributed to the fact that the signal at high frequencies is originating only from the exposed inner tip area. We thus assume that when there is leakage, the electrolyte trapped under the sealing area acts as a salt bridge that allows only for slow ion diffusion i.e. similar to a thin capillary. This would explain the observed results similarity for the highfrequency impedance and differences for both low-frequency impedance and capacities. Therefore, extended-duration SDC measurements should be interpreted with caution in the presence of leakage. The EIS signal modelling should be performed, by the analogy to SECCM , to identify and verify the most suitable equivalent circuit describing electrochemical processes in this system.