## 3 Varieties of Epoxide-Based Polymer Electrolyte
### Amines (Jeffamines)  
Amines have often been used as curing agents in epoxide polymerization reactions [40; 82; 83]. Reagents that are commonly cited in connection with epoxy curing are Jeffamines. Jeffamine is the trademark name of a series of polyether-based or polypropylene-based polymers that are terminated with primary amines [56; 84]. The monoamine version contains a single amino group whereas the diamine version has amino groups on both ends of the polyether chain [84]. Jeffamines can be grafted to or reacted with many types of polymers resulting in several co-polymerization options. These polymers include binders for cathodes and solid electrolytes with polyethylene-based backbones as well as the epoxide-containing materials that will be discussed here [85]. The advantages of Jeffamines for use in the context of epoxide-based polymer electrolytes include conferring high polymer chain flexibility, improved mechanical properties and high electrochemical stability [56; 85]. Perhaps most importantly, the distributed amine groups in Jeffamine-containing electrolytes are expected to decrease polymer crystallinity which causes increased ambient temperature ionic conductivity in these materials [86]. Additionally, Jeffamines are low cost and commercially available [85]. Jeffamines are anticipated to be compatible with most epoxy-based polymer electrolytes as amine-epoxy adduct chemistry has been well-studied [56; 82]. The use of Jeffamines in the production of epoxide-based polymer electrolytes offers the possibility for significant customization as a wide range of molecular weights and repeat unit types are available [56]. Lithium salts can be used to polymerize Jeffamines to produce solid polymer electrolytes and these materials can be combined with epoxides to yield novel polymer electrolytes (Scheme 3) [85; 87]. Figure 4: Lithium-ion transport in POSS and PEO-co-PPO polymer electrolyte. The PEO-co-PPO chains are straightened and kept apart by the POSS hub which facilitates lithium motion. Journal of Power Sources, 2020. Figure 5: **(A) Specific capacity in a Li-POSS and PEO-co-PPO polymer electrolyte-LFP cell at room temperature cycled at various rate between 2.5 and 4.0 V. (B) Capacity of the Li-POSS and PEO-co-PPO polymer electrolyte-LFP cell after 50 cycles at 0.2 and 0.1 C. Journal of Power Sources, 2020. **  
[PERSON] et al. took advantage of that fact that amine groups can improve electrolyte conductivity by interrupting ethylene oxide polymer chains with amine groups as they prepared polymer electrolytes with varying molecular weights using a polypropylene-based Jeffamine, DGEPEG and LiClO\({}_{4}\)[28]. These electrolytes were the most conductive when the total molecular weight of the polymer was 6000 Da. This material had a conductivity of 4 \(\times\) 10\({}^{-5}\) S/cm at room temperature and an activation energy (as determined be the Arrhenius method) of 0.187 eV. The electrolyte had a T\({}_{\text{g}}\) of \(-\)56 \({}^{\circ}\)C and was electrochemically stable up to 4.6 V vs. Li\({}^{+}\)/Li [28]. The impact of molecular weight was also noted by [PERSON] et al. who prepared a series of solid polymer electrolytes via a one-pot synthesis method using LiClO\({}_{4}\) to catalyze the cross linking of Jeffamine D2000 or D400 to SG80, an epoxy-siloxane polymer [29]. FTIR spectroscopy confirmed that the epoxide group was involved in the polymerization reaction as a result of the disappearance of the peak at 915 cm\({}^{-1}\) which corresponds to the epoxide functional group [29]. The electrolytes that were made with Jeffamine D2000 were shown to have better thermal and electrochemical properties. Increasing LiClO4 content was correlated with increasing Tg values. As LiClO4 content was increased, T\({}_{\text{g}}\) values for the polypropylene chains ranged between \(-\)59 and \(-\)11 \({}^{\circ}\)C and T\({}_{\text{g}}\) for the main polymer network increased from 7 to 30 \({}^{\circ}\)C [29].