Comparing the batch supplier and stated purity of the ILs (see Table ), with the results shown in Figure , we find that the electrochemical behaviour of both types can be observed (i) with batches supplied from a single supplier (here Iolitec) and (ii) with a stated purity of 99% and 99.9%. Hence, neither the purity nor the supplier is considered to be at the origin of the different behaviours observed in Figure . Nevertheless, it is very interesting that the electrochemical behaviour of all batches we have investigated can be divided into only two different types.