Fig. 3: Li deposition/dissolution cyclic behaviour between bare and MoS₂-coated Li symmetric cells.

a, Constant current charge/discharge voltage profiles for bare Li metal and MoS₂-coated Li symmetric cells cycled at a current density of 10 mA cm⁻². The inset shows the magnified voltage profile for the MoS₂-coated Li symmetric cell. Galvanostatic tests at 1 and 3 mA cm^–2 can be found in Supplementary Fig. 19. b,c, Nyquist plots of both cells after 15 cycles (b) and the end of charging/discharging test (c; 240 cycles for bare Li; 300 cycles for MoS₂-coated Li). The inset in c is the magnified Nyquist plot for the MoS₂-coated Li symmetric cell. d, SEM images showing the surface morphological changes between bare and MoS₂-coated Li before and after the cycling test at 10 mA cm⁻². The insets are the corresponding digital images of the electrodes. From the digital images of the electrodes acquired from the disassembled cells, the surface of the bare Li electrode clearly shows some signs of Li depletion as well as a porous layer. The surface of the MoS₂-coated Li, in contrast, shows minimal signs of damage with no dendrite formation. The SEM and the digital images for both MoS₂-coated and bare Li were taken after plating at the end of cycling test. e, Cross-section SEM image of the MoS₂-coated Li metal after 300 h of cycling and the subsequent EDS elemental mapping of Mo and S outlined by the dashed yellow box. The intensity maps confirm that the chemical make-up of the layered region on top of Li metal is MoS₂.