Secondly, as we do not observe a clear nanostructure responsible for columnar lithium with AFM, we replicate the experiment by Kasse et al. . To study during which part of the electrodeposition the additive plays a role, the working electrode is prepared in the electrolyte with the 25 mM H2O additive (wet electrolyte), after which the cell is rinsed, and the electrolyte is replaced with the dry electrolyte at different times during the electrodeposition process. The cell is rinsed 2 times with the dry electrolyte during the solvent exchange and all experiments are done galvanostatically at -1 mA/cm 2 , up to a total charge of ~-7.4 C/cm 2 . The resulting morphologies as observed by SEM and digital photos are shown in Figure shows the result when only the dry electrolyte is used (dry at 0 mC/cm 2 , green trace). Notably, in this case we observed that there was no adhesion between lithium and the substrate and only small amount of material was present on the substrate. Second, Figure and Figure depict samples where the dried electrolyte is introduced after respectively bringing the sample down to 0 V galvanostatically (dry at -7.2 mC/cm 2 , blue trace), and after completing half the process (dry at -3.7 C/cm 2 , red trace) in the wet electrolyte at -1 mA/cm 2 . It is worth pointing out that the V-|Q| trace shows no noticeable difference between the formation in the dry and the wet electrolyte. Figure shows that formation in the wet electrolyte enables adhesion of the deposit to the substrate but does not result in a columnar morphology. A similar experiment with a longer formation step at 0 V yields the same result (SI-4). This result therefore indicates that the formation affects the growth of lithium by means of the adhesion to the substrate, but that the additive also continuously plays a role during the growth. The continuous need for the additive to direct the growth is even more evident from Figure , where the columnar morphology switches to a non-directed mossy growth immediately upon exchange of the solvent.