There is some difference to the S2p data obtained for the reaction between an adsorbed BMP-TFSI monolayer and Li in Figure . The relative intensity in the low-BE peak (STFSI,dec-2, yellow) upon Li post-deposition and upon annealing up to 500 K, relative to that in the high-BE peak, is significantly higher in the monolayer than in the multilayer measurements. Most simply, this difference with respect to our findings for the other core levels may be explained by the formation of molecular, S-containing reaction intermediates with a local environment of the S atoms that is Li2S-like. This will lead to an S2p signal in the range of the STFSI,dec-2 signal, while the signals of the related N and O atoms still appear in the OTFSI,dec-1 and NTFSI,dec-1 ranges. This difference between the monolayer and multilayer experiments may be due to the direct interaction with the graphite substrate in the monolayer spectra, but alternatively also result from the different BMP-TFSI : Li ratios. Hence, for the S2p core level it is less obvious whether the presence of graphite results in a modification of the reaction behavior between BMP-TFSI and Li.