The batches of the IL presented in this study were, according to the supplier and confirmed The LPL was gradually decreased from 0.0 V to -0.5 V, -1.0 V, and -1.5 V. The UPL was kept constant at 1.7 V. A more detailed description of the experimental procedure can be found in the text to Figure . Each CV represents the first potential cycle recorded within the respective potential windows. The dotted lines show the same experiment with the same batch without any purification steps (shown in Figure ). by our Karl-Fischer measurements, delivered with a water content in the range of 5 to 100 ppm (see Table -2 in the SI). In this section, we illustrate the effect of reducing the water content for batch 3, which showed type I. This batch had an initial water content of 100 ppm, which was (i) reduced to 20-50 ppm in different measurements, by drying the IL in vacuum (10 -3 mbar) at 80 °C overnight (t ≥ 12 h) or (ii) reduced to less than 5 ppm by addition of 4 Å molecular sieve prior to treating the IL with the procedure in (i). Figure shows a comparison of the CVs obtained by both purification methods (solid lines) in a and b, compared to the measurements performed with the as-received IL (dashed lines). The experimental procedure was identical to that presented in Figure , where the LPL was gradually decreased. The data for both pre-treatments indicate that the removal of water has only minor effects on the different peaks. All peaks remain at the same potential. After the pre-treatment with heat and vacuum, only peak C1 decreases to some extent. Nevertheless, this effect is small and in literature it was shown that in some cases this treatment even leads to an increase of all observed peaks. Pre-treating the IL in addition with a molecular sieve, leads in all measurements to an overall decrease of peak A1, for all investigated lower potential limits. Decreasing the LPL to even more negative values after treatment with a molecular sieve, results in more significant changes in both scan directions for batches 3 and 4, as shown in the supporting information in Figure .