In
this paper, the structure of the LiFSI-[Py1,4]FSI
interface on Au(111) was investigated using in situ atomic force microscopy
and cyclic voltammetry. Raman and IR vibrational spectroscopy was
applied to evaluate the coordination of Li+ ions with the
FSI– anion. It was found that [Li(FSI)3]2– species are present in the solutions. The solvation
layer number and the forces decrease at higher concentration of Li+ ions. Therefore, the driving force, which is required for
the [Li(FSI)3]2– species to pass through
the solvation layer to reach the electrode surface, is lowered. This
increases the onset potentials of the SEI layer formation and lithium
underpotential deposition (Li-UPD) at high Li+ concentrations.
It was found that the onset potentials are −0.8, −0.7,
−0.6, and −0.4 V for the Li-UPD and −2.0, −1.6,
−1.4, and −1.3 V for the SEI layer formation, vs the
Pt-(quasi)reference electrode, corresponding to Li+ concentrations
of 0.1, 0.25, 0.5, and 1 M, respectively.