The Importance Of Ionic Conductivity Analysis

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Results and discussion
3.1 Ionic conductivity measurements The complex impedance plots for the polymer electrolytes with different amounts of TBAI /LiI is shown in Fig. 1. It can be displayed that the ionic conductivity increases with the increase in TBAI salt content and reaches the maximum value of 1.737×10-3 S cm-1 at 298 K for 60 % of TBAI content, beyond decreases on further addition of TBAI. At a low content of TBAI, the conductivity is low due to the small number of charge carriers in the electrolytes. However, with an increase in TBAI content (60 %), the ionic conductivity increases because of the buildup of charge carriers [8-9]. The added TBAI may coordinate with the iodide ions, which promote the charge transport of iodide ions
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The ionic conductivity of a polymer electrolyte relies on the concentration of carriers and their mobility, the ionic conductivity of polymer gel electrolytes increases with temperature due to the higher segmental motion of polymer chain in the amorphous phase. The temperature reliance of the ionic conductivity of the polymer electrolytes is following by an Arrhenius Eq. (2) [10]: σ = σ₀ 〖exp-〗_KT^Ea …show more content…
While the high dielectric constant favors salt dissociation, the low viscosity would lead to high ionic mobility in the electrolytic solution is formed by dissolving the two ionic salts in the EC/PC co-solvent [13]. From Fig. 1, the activation energy values, which correspond to the Arrhenius plot, are almost constant for all six gel electrolyte samples studied and independent of the salt concentration ratios (TBAI/LiI). The calculated activation energies (Ea) of polymer electrolyte systems are given in Table 2. For a given salt (or a salt mixture), the activation energy is largely independent of the salt concentration for low and moderate concentrations and the type of salt used but depends essentially only on the type of solvent, in particular on the nature of the solvent heteroatom. The dependence of the ionic conductivity of the present gel polymer electrolytes on salt concentration is similar to that reported by others

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