## 3 Varieties of Epoxide-Based Polymer Electrolyte
### Amines (Jeffamines)
However, ionic conductivity was observed to be the highest when the lithium salt to polypropylene oxide ratio was 15 with small decreases in conductivity occurring with increasing LiClO4 loading [29]. Lithium conductivity on the order of 10\({}^{-7}\) S/cm was measured at room temperature and the material was thermally stable until about 385 \({}^{\circ}\)C [29]. Similarily, [PERSON] et al. prepared solid polymer electrolytes using Jeffamine D400 and DGEPEG with LiClO4 salt [30]. These materials had T\({}_{\text{g}}\) values ranging between \(-\)41 and 15 \({}^{\circ}\)C with increasing LiClO\({}_{4}\) content and were thermally stable up to about 300 \({}^{\circ}\)C [30]. As was observed in the Jeffamine D2000-epoxy-siloxane system described above, peak conductivity was achieved when the lithium to polypropylene oxide ratio was 15 [30]. Room temperature ionic conductivity was on the order of 10\({}^{-7}\) S/cm [30]. Jeffamine-epoxy adducts are versatile and have also been used in the synthesis of hybrid polymer electrolytes. [PERSON] et al. prepared a series of hybrid polymer electrolytes containing diglycidyl ether of bisphenol A (DGEBA), poly(ethylene glycol) (PEG), LiTf and nano-silica using either Jeffamine D400 or metaxylylenediamine (MXDA) as a curing agent [31]. The T\({}_{\text{g}}\) values ranged between 40 and 70 \({}^{\circ}\)C depending on both the silica content and the lithium salt content of the polymer electrolyte with increased silica content (0 to 10 wt%) and increased lithium salt content (lithium to ether oxygen ratios between 0.1 and 0.15) resulting in decreased T\({}_{\text{g}}\)[31]. The ionic conductivity of these materials (lithium to ether oxygen ratio of 0.125) is between 10\({}^{-5}\) to 10\({}^{-6}\) S/cm when the nano-silica content is between 0 and 10 wt% with increasing nano-silica content resulting in higher ionic conductivities [31]. At all nano-silica loadings, the ionic conductivity of the samples that were cured with Jeffamine D400 is greater than that of the samples that were cured with MXDA as a result of the aromatic compound making the crosslinked epoxy network more rigid (Figure 6) [31]. In addition to Jeffamines, other amine-containing polymers have been used to produce epoxide-based solid polymer electrolytes [32; 33; 34]. [PERSON] and [PERSON] combined lithiated diamine diphenylsulfone (DDS) and DGEPEG to produce electrolyte films that were stable up to about 300 \({}^{\circ}\)C and had a T\({}_{\text{g}}\) of 40 \({}^{\circ}\)C [32]. As a result of the relatively high T\({}_{\text{g}}\), these films proved to be less conductive than other epoxide-based electrolytes containing amines with an ionic conductivity on the order of 10\({}^{-8}\) S/cm at room temperature [32]. Other diamine reagents that have been used to produce solid polymer electrolytes with improved thermal and electrochemical properties include poly(ethylene glycol) diamine (NPEG) which was used by both [PERSON] et al. and [PERSON] et al. to prepare a series of epoxide-based solid polymer electrolytes [33; 34]. Polymerizing NPEG with trimethylolpropane triglycidyl ether (TMPEG) in the presence of LiTFSI resulted in the formation of solid polymer electrolytes with T\({}_{\text{g}}\) values ranging from \(-\)40 to \(-\)43.5 \({}^{\circ}\)C depending on the molecular weight of the NPEG reagent and were thermally stable up until about 300 \({}^{\circ}\)C [33]. Relatively high room temperature ionic conductivities were reported, 1.10 \(\times\) 10\({}^{-4}\) S/cm in the sample that was made with NPEG4000 [33]. The lithium ion transference number, which was calculated for this sample at 60 \({}^{\circ}\)C based on conductivity data using the Vincent-Bruce method, was 0.27 [33]. The NPEG-TMPEG crosslinked electrolyte was shown to be significantly more electrochemically stable than PEO, 5.4 V versus less than 4.0 V with respect to Li\({}^{+}\)/Li [33]. In addition, the NPEG-TMPEG electrolyte was shown to retain up to 90.6% capacity after 100 cycles at 60 \({}^{\circ}\)C in an Li-Li call at a cycling rate of 0.2 C [33].