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

• This work combines MD simulation & XAS to study polymer electrolytes.
• Doping KSCN can slightly induce the conformational change of TET chain.
• Both polymer and anions are included in first solvation shell of cation.

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.

A snapshot from MD simulation of TET:KSCN complex that represent the solvation structure of K+ ion by TET oxygens and SCN− anion. The most probable case is the solvation by 1 TET chain with 3 oxygen atoms and 2 SCN− anion.Figure optionsDownload as PowerPoint slide