Solvation structure and dynamics of a small ion in an organic electrolyte

[Display omitted] •A non-canonical CH…N hydrogen bond is formed between thiocyanate ion and PC.•Non-Condon effect is observed from the FTIR spectrum and lifetime decays.•The fast timescale of spectral diffusion is governed by the hydrogen bond formation/dissociation process.•The spectral diffusion and solute reorientation dynamics are controlled by similar processes. Organic carbonates are commonly used as electrolytes in commercial lithium-ion batteries. A detailed interpretation of the solvation structure and dynamics of the electrolyte around ions is necessary to understand the charge/discharge process in batteries. This work combines infrared absorption spectroscopy with quantum chemical calculations and molecular dynamics simulations to decipher the solvation structure of propylene carbonate, a cyclic carbonate, around the dissolved thiocyanate ion. Two dimensional infrared spectroscopy and polarization-selective pump probe spectroscopies have been utilized to extract the timescales of solvent fluctuation and the solute reorientational dynamics. The similarity in the slow timescales for the solute and the solvent dynamics signifies that similar processes control both dynamics.