## 2 Results
### Thermal Properties and Phase Behavior
These values were obtained from the DSC cooling scans. “—” indicates transitions not observed using DSC. Data for C18 LiTFSI were originally reported in [21]. Figure 3: Smectic to isotropic transition temperatures from DSC based on ratio and additive molecule. Figure 4 shows SAXS and WAXS data at all measured temperatures during cooling for the 0.3:1 ratios of each electrolyte. The semicrystalline phase is observed in all three cases at 25 \({}^{\circ}\)C and 50 \({}^{\circ}\)C. Presence of a sharp peak in the WAXS region of q > 1 A\({}^{-1}\) distinguishes the semicrystalline phase with atomic level ordering from the liquid crystal phase. The smectic phase is observed at 75 \({}^{\circ}\)C, 90 \({}^{\circ}\)C and 120 \({}^{\circ}\)C for C18 MS, and 70 \({}^{\circ}\)C and 100 \({}^{\circ}\)C for C18 ES and C18 IPS. Observe through SAXS and WAXS of a phase with only evenly spaced long-range ordering in the SAXS region and an amorphous halo in the WAXS region confirmed the formation of the smectic (layered) phase in the material [24]. For example, for C18 MS0.3 at 75 \({}^{\circ}\)C, SAXS peaks are present at q = 0.19 A\({}^{-1}\), 2q = 0.38 A\({}^{-1}\), and 3q = 0.57 A\({}^{-1}\). The isotropic phase is observed at all higher temperatures, where the amorphous halo remains in the WAXS region, and broad peaks indicative of disorder are present in the SAXS region. The full width at half maximum of the primary (lowest q) SAXS peak for C18 MS0.3 increases from 0.0023 A\({}^{-1}\) at 120 \({}^{\circ}\)C (smectic phase) to 0.068 A\({}^{-1}\) at 160 \({}^{\circ}\)C (isotropic phase). As seen using DSC, the trends for the temperature ranges at which the smectic phase occurs is generally consistent across all three additive molecules (Tables 2-4). Additional SAXS/WAXS data can be found in Appendix A.  
Figure 4: SAXS and WAXS measurements for 0.3:1 ratio blend electrolytes of (**a**) C18 MS, (**b**) C18 ES, and (**c**) C18 IPS with C18 LTFSI on cooling from 200 \({}^{\circ}\)C to 25 \({}^{\circ}\)C.  
The SAXS data confirmed the layered ordering of the ionic domains and the presence of the liquid crystal phase. The length of the C18 LiTFSI and the additive molecules themselves is estimated to be \(\sim\)23 A; this indicates a level of overlap of the hydrophobic tails or the ionic and polar head groups because the d-spacing, or length between repeat units in the layers, is smaller than two molecules end-to-end. Therefore, we anticipate that the liquid crystalline phases are likely SmA with interdigitation (a common result for ionic liquid crystalline molecules with aliphatic tails) or potentially SmC; use of polarized optical microscopy, 2-D SAXS of an aligned sample, and/or resonant X-ray scattering are necessary to conclusively identify the liquid crystalline phases [24; 25; 26]. If interdigitated, the interdigitation increases for the materials in the smectic liquid crystal phase; this is indicated by the smaller d-spacing for the mixed materials than the pure crystalline additives. Compared to the d-spacing of pure C18 LiTFSI at 120 \({}^{\circ}\)C, 29 A, there was only a 1-4 A increase in layer spacing in the mixtures. \begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline
**Material** & **200 \({}^{\circ}\)C** & **160 \({}^{\circ}\)C** & **130 \({}^{\circ}\)C** & **100 \({}^{\circ}\)C** & **70 \({}^{\circ}\)C** & **50 \({}^{\circ}\)C** & **25 \({}^{\circ}\)C** & **q (Å\({}^{-1}\)) (70 \({}^{\circ}\)C)** & **d = 2\(\pi\)/q (Å)** \\ \hline C18 IPS0.05 & ISO & SM & SM & SM & SM & CRYSTAL & CRYSTAL & 0.21 & 30 \\ C18 IPS0.1 & ISO & SM & SM & SM & CRYSTAL & CRYSTAL & 0.21 & 30 \\ C18 IPS0.2 & ISO & ISO & SM & SM & CRYSTAL & CRYSTAL & 0.21 & 30 \\ C18 IPS0.3 & ISO & ISO & ISO & SM & SM & CRYSTAL & CRYSTAL & 0.21 & 30 \\ C18 IPS0.5 & ISO & ISO & ISO & ISO & CRYSTAL & CRYSTAL & 0.21 & 30 \\ C18 IPS1.0 & ISO & ISO & ISO & ISO & CRYSTAL & CRYSTAL & 0.15 & 42 \\ \hline \hline \end{tabular}
\end{table}