Fig. 3: Morphological and structural evolution of deposited Li metal.

a‒c Top-view SEM images and d‒f thickness variations of the deposited Li metal on Cu, Cu-Ag, Cu-AgC and Cu-AgC+Ag electrodes between cycle 1st and cycle 50th with an area capacity of 6.5 mAh cm⁻² from NCM90 | |Cu based cells, and data are presented as mean values ± standard deviation (Data points are three randomly selected thickness values). g, h 3D reconstructed morphology using X-ray computed tomography (CT), showing porosity/cracks and Ag distribution at fully charged state (4.4 V) from NCM90 | |Cu based cells with an area capacity of 6.5 mAh cm⁻² in cycle 10th. i Quantification of porosity and Ag content percentage of deposited Li metal across different electrodes. j‒l Cross-sectional SEM images obtained via FIB milling, illustrating deposited Li metal at 4.4 V (fully charged) and 3.0 V (discharged) after 30th cycled in NCM90 | |Cu cells with an area capacity of 6.5 mAh cm⁻². m Fitted Nyquist plots of NCM90 | |Cu cells at the discharged state of 3.0 V, recorded from the 1st to 30th cycles. All electrochemical testing were conducted at 25 ± 1 °C, NCM90 | |Cu full cells were cycled at a low current rate of 0.1/0.1 C for conditioning (1 cycle) and standard current rate of 0.2/0.33 C for cycling between 4.4 to 3.0 V (1 C = 240 mA g⁻¹) before disassembling.