Fig. 3: Analysis of the Li propagation behaviour and volume change of the Ag-C interlayer.

a Schematic of the in-situ optical microscopy (OM) setup to observe Li propagation through the Ag-C interlayer. b Galvanostatic charging voltage profile of the full cell from in situ OM analysis with the inset showing the direction of Li propagation. c In situ OM images of the Ag-C layer during the galvanostatic deposition of Li. The formation of Li precipitates intensifies as the deposition time increases (red circle). d Cross-sectional SEM images of the full cell before and after charging at current densities of 0.1 C and 0.5 C.