**6. [70PAN + 30NaF] gel polymer electrolyte system**

#### **6.1 Discharge characteristics**

A proton battery using the membrane with the maximum ionic conductivity was constructed with sodium (Na) as an anode material and a mixture of iodine (I2),

*Structural, Optical, and Electrical Studies of PAN-Based Gel Polymer Electrolytes… DOI: http://dx.doi.org/10.5772/intechopen.98825*

carbon, and a piece of GPE taken as the cathode electrode between the 70PAN:30NaF electrolyte film [5]. **Figure 10** represents the discharge characteristics of the electrochemical cell with an applied load of 100 k Ω at room temperature. From these results, the OCV of the cell was observed for 118 hours and plotted against time, as shown in **Figure 14**. A stabilized voltage of 2.78 V was obtained from the cell. The discharging curve initially decreases with the voltage of the cell, which may be due to the polarization effect. **Table 5** lists the OCV and discharge time for the cell [32–37].

A solid-state electrochemical cell was fabricated with an anode Na/PAN:NaF (70:30)/cathode (I2 + C + electrolyte+Al2O3). The thickness of both the electrodes is 1 mm. The surface area and thickness of the PAN+NaF + Al2O3 GPE were 1.28 cm2 and 128 μm, respectively. The discharge characteristics of the cell for a constant load of 100 kΩ were evaluated at room temperature as shown in **Figure 14**.

The initial sharp decrease in the voltage in these cells may be due to polarization and the formation of a layer of sodium salt at the electrode–electrolyte interface [38–41]. Cell parameters such as OCV, SCC, current density, power density, energy density, and discharge capacity have been evaluated in the highest conducting GPE

#### **Figure 14.**

*Discharged curve of the solid-state cell configuration of Na/PAN:NaF (70:30)/cathode (I2+ C + electrolyte+ Al2O3) at a load of 100 kῼ.*


#### **Table 5.**

*Cell parameters of PAN:NaF (70:30) gel polymer electrolytes.*


#### **Table 6.**

*Cell parameters of the PAN:NaF + Al2O3/(I2+ C + electrolyte) polymer electrolyte battery.*

#### **Figure 15.**

*Discharge characteristics of PAN:NaF complexed with 3 wt% Al2O3 nanofiller polymer electrolyte electrochemical cell (load =100 k*Ω*).*

system PAN:NaF (70:30) + nanofiller (Al2O3) in this electrochemical cell. **Table 6** shows the obtained data. The current density is calculated using the SCC value and area of the cell. The power density value is obtained by taking the OCV and weight of the cell into consideration. The energy density value is calculated by evaluating the time taken for the plateau region [5]. From **Table 6**, it is obvious that the cell with the composition PAN:NaF (70:30) + nanofiller Al2O3 exhibits better performance [26]. It is confirmed that gel-state cell parameters are better than the earlier reported sodium-based polymer electrolyte cell system (**Figure 15**) [27–31].

#### **7. Conclusions**

Proton-conducting GPEs consisting of NaF salt dissolved in a plasticizing solvent of EC and DMF, immobilized in a host polymer 70PAN + 30NaF + (1–4 wt%) Al2O3 (nanofiller) were synthesized and characterized. The complexation of the salt and nanofiller with the polymer was confirmed by ED. UV–Vis light absorption reveals that the chemical structure of the polymer is identical to that of the polymer formed electrochemically. The various absorption rates given for different wavelengths and optical energy band gaps were determined. The tensile test of the prepared samples was verified by a stress–strain graph. The tensile strength was increased to 5.9 MPa for the polymer electrolyte with 3 wt% nanocomposite compared to the filler-free electrolyte. A decrease in the degree

*Structural, Optical, and Electrical Studies of PAN-Based Gel Polymer Electrolytes… DOI: http://dx.doi.org/10.5772/intechopen.98825*

of crystallinity and an increase in the amorphous nature were observed, while an increase in conductivity was observed with increasing nanofiller concentration and temperature. The heat flow observed by DSC technique that the transference data indicates the conduction in the polymer electrolyte is predominantly due to ions rather than electrons. Using a PAN:NaF (70:30) GPE system, a solid–state battery (Na/PAN:NaF (70:30) + EC + DMF/(I2 + C + electrolyte)) was fabricated, and its discharge characteristics were studied. These results were found to be comparable with existing results.
