Supplementary Material

The supplementary material provides Table S1: details of all MD simulation boxes used in this work; Table S2: coordination statistics showing the percentage of solvent- and anion-bridged cation-cation configurations for Li+ and Na+; Tables S3-S7: time constants and stretching exponents obtained by fitting the cation-anion pair autocorrelation functions; Tables S8-S12: time constants and stretching exponents obtained by fitting the cation-solvent pair autocorrelation functions; Tables S13-S17: diffusion coefficients of the mixtures at different temperatures and as a function of the molar fraction of solvent; Fig. S1: pair radial distribution functions of mixtures with xsolvent = 0.67, calculated from the MD simulation trajectories at 450 K; Figs. S2-S6: weighted connectivity matrix between solvent molecules and anions mediated by the alkali cations at xsolvent = 0.67 and as a function of the temperature; Fig. S7: total X-ray structure factors of sulfolane mixtures with LiBF4 as a function of mole fraction of solvent; Figs. S8-S9: cluster-size analyses for LiBF4 in SL as a function of the mole fraction of the solvent different temperatures; Fig. S10: semi-log plots of the continuous dimer time autocorrelation functions of the cation-anion and solvent-cation pairs; Figs. S11-S12: Arrhenius plots of the relaxation processes at different molar fractions of solvent; Fig. S13: values of the stretching coefficient as a function of the temperature for the electrolytes studied.