Thermal, dielectric and conductivity studies on PVA/Ionic liquid [EMIM][EtSO4] based polymer electrolytes

Polymer electrolyte films of (PVA+15 wt% LiClO4)+x wt% Ionic liquid (IL) 1-ethyl-3-methylimidazolium ethylsulfate [EMIM][EtSO4] (x=0, 5, 10, 15) were prepared by solution cast technique. These films were characterized using TGA, DSC, XRD and ac impedance spectroscopic techniques. XRD result shows that amorphosity increases as the amount of the IL in PVA+salt (LiClO4) is increased. DSC results confirm the same (except (PVA+15 wt% LiClO4)+10 wt% IL). The dielectric and conductivity measurements were carried out on these films as a function of frequency and temperature. The addition of IL significantly improved the ionic conductivity of polymer electrolytes. Relaxation frequency vs. temperature plot for (PVA+15 wt% LiClO4)+x wt% IL were found to follow an Arrhenius nature. The dielectric behavior was analyzed using real and imaginary parts of dielectric constant, dielectric loss tangent (tan δ) and electric modulus (M′ and M″).

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► Ionic liquid amorphosizes the PVA+LiClO4 polymer electrolytes.
► Thermal stability of PVA/LiCiO4 and IL based system decreases with IL content.
► The permittivity increases in low frequency region with IL content and decreases with frequency.
► The lower value of M′ and M″ at lower frequencies shows that electrode polarization effect is negligible.