# Development on Solid Polymer Electrolytes for Electrochemical Devices
## 3 Basic Solid Polymer Electrolytes
### Preparation Methods of SPEs
[35] have obtained thin films of SPEs containing poly(3,3-dimethylpentane-2,4-dione) as the polymer matrix and LiTFSI salt after pressing the dried homogenous mixture between two polytetrafluoroethylene (PTFE) plates, under high pressure (2 MPa) and temperature (100 \({}^{\circ}\)C) conditions, inside an argon-filled glove box for 1 h. The polymer was desiccated in vacuum state before uniformly mixing and pulverizing the polymer and salt. Although the ambient conductivity value was low, of the order of 10\({}^{-8}\) S cm\({}^{-1}\), it gave a rather high Li\({}^{+}\) ion transference number (\(t_{Li^{+}}\) = 0.70) at 80 \({}^{\circ}\)C [35]. For the sake of comparison, the LiTFSI-containing SPE but with PEO as polymer host has been prepared by the same method and it showed a higher ambient conductivity (10\({}^{-5}\) S cm\({}^{-1}\)) with low Li\({}^{+}\) transference number (\(t_{Li^{+}}\) = \(\sim\)0.15) [35]. High cationic transference numberis useful for application in Li-ion batteries. Table 4 shows some selected works of simple SPEs systems available in the literature. \begin{table}
\begin{tabular}{c c c c c} \hline
**Electrolyte System** & **Preparation Method** & **Conductivity \(\sigma\) (S cm\({}^{-1}\))** & **Important Findings** & **Reference** \\ \hline PEO-NaSCN & Solution casting & \(9.86\times 10^{-8}\) & \(t_{ion}=0.85\) & \\  & & (RT) & \(n=1.21\times 10^{20}\) m\({}^{-3}\); & [36] \\  & & & \(\mu=5.10\times 10^{-7}\) m\({}^{2}\) V\({}^{-1}\) s\({}^{-1}\) & \\ \hline  & & & Thermal stability \textgreater{} 300 \({}^{\circ}\)C; \(T_{g}=-36.3\)\({}^{\circ}\)C & \\  & & \(3.16\times 10^{-6}\) & \(\text{Na}_{+\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{ \text{\text{\text{\text{\text{\text{\text{ \text{     \text{         }}}}}}}}}}}}}\) & \\ PEO-NaFNSI [EO]/[Na]=15 & Solution casting & \((80\)\({}^{\circ}\)C) & Oxidation potential \textgreater{} 4.87 V Na\({}^{+}\)/Na & \\  & & \(3.36\times 10^{-4}\) & NaCu\({}_{1/9}\)Ni\({}_{2/9}\)Fe\({}_{1/3}\)Mn\({}_{1/3}\)O\({}_{2}\)/SPE/Na cell: & \\  & & \((30\)\({}^{\circ}\)C) & Initial capacity \textgreater{} 122.4 mAh g\({}^{-1}\) (0.1 C, 80 \({}^{\circ}\)C)70\% & \\  & & & capacity retention at 1 C after 150 cycles (80 \({}^{\circ}\)C) & \\ \hline PEO-LiCF\({}_{3}\)SO\({}_{3}\) & Ball-milling and hot press & \(1.00\times 10^{-6}\) & \(T_{g}=-64.4\)\({}^{\circ}\)C; \%\(\times\)XC = 37.3\% & [38] \\  & & & \(\text{\%}\)\(\times\)C = 9.3\% & \\ PAN-LiTFSI & Solution casting & \(2.54\times 10^{-4}\) & ITO-WO\({}_{3}\)/SPE/CeO\({}_{2}\)-TiO\({}_{2}\)-ITO ECD: & [39] \\  & & (25 \({}^{\circ}\)C) & Cathodic coloration at \(-1.25\) V; & \\  & & & Anodic bleaching at \(-0.40\) V & \\ \hline CMC-(NH\({}_{4}\))\({}_{2}\)CO\({}_{3}\) & Solution casting & \(7.71\times 10^{-6}\) & \(\text{\%}\)\(\times\)XC = 30.9\%; \(t_{ion}=0.98\) & [40] \\  & & (30 \({}^{\circ}\)C) & CMC film without salt: \(\sigma=10^{-9}\) S cm\({}^{-1}\) & [40] \\ \hline  & & & \(E_{A}=0.38\) eV & \\  & & & \(n=15.24\times 10^{18}\) cm\({}^{-3}\); & \\  & & & \(\mu=11.44\times 10^{-6}\) m\({}^{2}\) V\({}^{-1}\) s\({}^{-1}\), & \\ NaCMC-Na\({}_{2}\)S-S & Solution casting & \(2.79\times 10^{-5}\) & \(D=2.94\times 10^{-7}\) cm\({}^{2}\) s\({}^{-1}\) & \\  & & (30 \({}^{\circ}\)C) & TiO\({}_{2}\)-CdS-ZnS/SPE/Pt DSDSC (light intensity of & [41] \\  & & & 100 \(\text{nm}\) ON cm\({}^{-2}\)). & \\  & & & \(\text{OCV}=0.41\) V; \(j_{sc}=4.92\) mA cm\({}^{-2}\); & \\  & & & \(\text{\