## 2 Thermal and Electrochemical Parameters of Interest
### Electrochemical Stability Window  
Electrochemical stability windows, as reported in Table 1, were provided for many of the polymer electrolytes that are discussed in this review. The electrochemical stability window is of some importance to a functioning battery as it determines both the open circuit voltage and the life cycle of the battery [70]. For a given material, the electrochemical stability window is determined by the reduction and oxidation potentials that are respectively governed by the conduction band maximum and the valence band minimum [71]. The energy gap between the conduction band maximum and the valence band minimum must be greater than the difference between the electrochemical potentials of the anode and the cathode for the electrode material to be stable [71]. Despite the seemingly simple explanation for electrochemical stability, electrochemical stability windows in polymer electrolytes tend to be largely unexplored. This is a result of the large variety of chemical and morphological variations that can exist in solid polymer electrolytes [70]. These effects, along with differences in interactions between the polymer and the salt and between the electrolyte and the electrodes can make it particularly challenging to accurately predict electrochemical stability windows using theory, comparisons with other materials or computational methods. For example, PEO (which has been extensively studied) is often rated to have an electrochemical stability window of less than 4 V [72]. As PEO is exclusively comprised of C-O-C bonds and is terminated by -OH, some authors have anticipated that one of these structural motifs is more susceptible to oxidative damage than the other. As diglycidyl ether of polyethyleneglycol (DGEPEG), an epoxide-terminated polyether (and a major component of many of the polymers discussed here) has been shown to be stable up to 4.3 V, it is anticipated that it is the terminal -OH in PEO that most susceptible to oxidative damage [72]. This means that the polymer electrolytes discussed here, may be expected to be more stable than PEO even though they contain C-O-C bonds as they are not -OH terminated and their crosslinked nature may afford more stability [70]. Therefore, the 4 to 5.4 V that are reported by most of the authors who are cited here can be reasonable when variations in electrolyte components and crosslinking motifs are accounted for. That being said, it is important to note that there is a significant difference between being stable over one cycle (for example linear sweep voltammetry experiments which tend to provide more of a guess at the electrochemical stability window as opposed to a certain conclusion), being stable for a few hundred cycles (what most of the publications presented here report)and for thousands of cycles (the industry requirement).The latter requirement is the most difficult to achieve as the Coulombic efficiency must be close to 1 [73; 74; 75]. Additionally, individual reported electrochemical stability windows can vary as a result of different polymer-lithium salt interactions and interactions with the electrodes. For example, [PERSON] et al. showed that LiBF\({}_{4}\) may increase oxidative stability relative to LiTFSI [10]. Moreover, silicones have been shown to be highly compatible with lithium electrodes which could contribute to the larger windows of electrochemical stability that have been reported in the silicone-containing polymer electrolytes that are discussed here (Table 1) [76]. Although differences in experimental methods, polymer electrolyte composition and the extent of crosslinking make the electrolytes that are presented in Table 1 difficult to compare directly, various parameters allow the merits of each of these materials to be evaluated. Here we are primarily interested in how the presence of epoxides and other components of these electrolytes such as silicones, amines and plasticizers impact the thermal and electrochemical properties of these materials and affect their suitability for use as electrolytes in lithium batteries.