Application of X-ray absorption spectroscopy and molecular dynamics simulation to study the atomistic solvation structure of tetraglyme:KSCN electrolytes

The atomistic solvation structure of tetraglyme:KSCN (TET:KSCN) electrolytes with various K⁺:ether oxygen (M:O) ratio were studied by a combination of molecular dynamic (MD) simulation and Extended X-Ray Absorption Fine Structure (EXAFS) called “MD-EXAFS” method. This method gives useful information at the atomistic scale including the average distance between atom pair around the probed ion (R₀) and Coordination Number (N). MD simulation results suggest that K⁺ ions are mostly coordinated to ether oxygen and the conformation around C–C bond prefer the gauche state and TET becomes more compact shape. K⁺ ions are also coordinated to thiocyanate (SCN⁻) anion at both nitrogen and sulfur atoms due to strong electron delocalization over three atoms in SCN⁻ (S, C and N). A comparison between MD-EXAFS with the experimental spectra gives an overall good agreement for both frequency and amplitude of the oscillations.