Unfortunately, these latter signals are close to the low BE peak (FTFSI,dec-1) in the experimental spectra in Figure . Therefore, they may also be due to a later reaction product such as LiF (see discussion below), and an unambiguous confirmation or exclusion of these latter species is not possible based on their BEs. For the O1s region, the situation is in so far different as the BE of the low-BE peak is only reproduced by the binary adsorbates (see below), while all other species show BEs in the range of the high-BE peak (OTFSI+Li and OTFSI,dec-1). Also in this case, the up-shift in BE upon Li coadsorption, from the OTFSI to the OTFSI+Li peak, is reproduced well. A similar situation is obtained for the S2p region, where all adsorbed molecular species, both the initial IL and the initial reaction products, appear in the BE range of the high-BE peaks (STFSI+Li and STFSI,dec-1). Also the up-shift in BE upon coadsorption of Li, from STFSI to STFSI+Li, is again well reproduced. Finally, similar to the O1s state, the BE of the low-BE STFSI,dec-2 peak is only reproduced by the binary adsorbed species (Li3S, Li4S, see below), Most complex is the situation for the N1s region. To begin with, the up-shift of the BE from Finally, we will focus on the thermodynamically stable final products of the reaction of BMP-TFSI and Li. For reaction with bulk BMP-TFSI, equivalent to the multilayer film, we found the binary salts composed of Li and elements of TFSI such as Li2O, LiF, Li3N, Li2S or LiCN to be most stable. Similar type results were reported from a DFT-based molecular dynamics study on the interaction of the closely related pyrrolidinium (Pyr) based ionic liquid Pyr-TFSI with Li by Merinov et al., who found complete decomposition of TFSI in the presence of a large excess of Li. In their work, F atoms were typically coordinated by 4 or 3 Li atoms. Comparable results were reported also in an earlier DFT-based molecular dynamics study by Yildirim and