The results in Figure are in stark contrast with the prevailing explanation of HF-mediated formation of LiF being responsible for columnar growth, where LiTFSI is often used as a reference salt resistant to hydrolysis, and does not yield columnar structures . It is worth pointing out that we obtain the same results even when using the electrolytes directly after preparation, as a > 48 h waiting period after the addition of H2O is typically required for the formation of HF in LiPF6 based electrolytes . The columnar morphologies obtained from LiTFSI and the fluorine-free LiClO4 electrolytes are therefore a key result, as it rules out such a mechanism being responsible for this particular mode of growth. Figure shows that layers of arbitrary thickness can be grown from the LiTFSI salt with 25 mM of H2O at a current density of -1 mA/cm 2 , which we control by means of the plating duration and is demonstrated here for layers up to 30 µm (~-21.6 C/cm 2 ). The insets again show digital photos of the samples, where we note that a pronounced angular dependence of the reflection becomes apparent for thicker layers (top images, tilted, bottom images, perpendicular). From the SEM images we further estimate the thickness of the layer (Figure ) and the diameter of the columns (Figure ) as a function of the plating time. We observe that the relative error of the measured height decreases over time, as compared to the height expected from the equivalent charge, yielding a relative error < 10% for the thickest layer, while the column diameter increases with the layer thickness but saturates at ~600 nm. This seems to imply that the layer initially has some voids, which close through expansion of the column diameter over time. Based on these results we typically electrodeposit -7.4 C/cm 2 (equivalent to 10 µm of lithium) in the remainder of the text.