Objective: Polyethylene oxide (PEO) composed of 10 wt% ammonium bifluoride
(NH4HF2) exhibited higher conductivity of 5.96x10-6 S/cm as compared to other concentrations
of salt at room temperature. The effect of additives, i.e., nano-sized fumed silica concentration
as nanofiller and propylene carbonate (PC) concentration as plasticizer on electrical, structural,
as well as mechanical property studies of polymer electrolytes has been studied.
Methods: The ionic conductivity, as well as dielectric studies of polymer electrolytes consisting
of polyethylene oxide and different (x wt%) ammonium bifluoride (x=1, 2.5, 5, 10
and 15 wt %), have been measured using complex impedance spectroscopic technique. X-ray
diffraction (XRD) and differential scanning calorimetry/thermogravimetric analysis (DSC/
TGA) studies have been conducted to observe the effect of additives on crystalline phase,
crystallite size, melting temperature and weight loss of different polymer electrolytes. The
effect of additives on the mechanical properties (tensile strength, modulus of elasticity and %
elongation at break) of different polymer electrolytes has also been studied by Universal
Testing Machine (UTM).
Results: The maximum conductivity achieved was 1.55× 10-4 S/cm in case of plasticized
nanocomposite polymer electrolytes with the simultaneous presence of 3 wt% fumed silica
and 0.3 ml propylene carbonate. The variation of ionic conductivity at different temperatures
and activation energy values of different polymer electrolytes were also measured and observed
in good correlation.
Conclusion: The observed enhancement in the ionic conductivity of polymer electrolytes
with additives is due to an increase in carrier concentration, amorphous content, chain flexibility,
as well as the formation of more conducting pathways. Hence, this new approach led
to the development of plasticized nanocomposite polymer electrolytes with high ionic conductivity
and improved structural and mechanical properties.