Towards magnesium ion conducting poly(vinylidenefluoride-hexafluoropropylene)-based solid polymer electrolytes with great prospects: Ionic conductivity and dielectric behaviours

A simple solid polymer electrolyte (SPE) system based purely on poly(vinylidenefluoride-hexafluoropropylene) [P(VdF-HFP)] and magnesium trifluoromethanesulfonate (MgTf) is synthesised via solution casting technique with acetone as solvent. The SPEs produced exhibit high ionic conductivity of ∼10−3 S/cm at ambient temperature when 40 wt.% of MgTf is incorporated. The major focus of this work is on ionic conductivity and dielectric behaviours. Three dissimilar types of impedance spectra have been identified and differentiated by magnitude of ionic conductivity. The trend of ionic conductivity increases almost proportionally to the content of magnesium salt and can be related to an increase of amorphous phase at high level of dopant salt. This SPE system has also been found to possess Arrhenius temperature dependence. This study discusses three samples with 10, 25 and 40 wt.% of magnesium salt, representing low, intermediate and high concentrations of magnesium salt which are examined in frequency-dependence conductivity, dielectric permittivity and dielectric modulus studies.

► The SPE exhibits high ionic conductivity of ∼10−3 S/cm at 40 wt.% of MgTf salt.
► Conductivity is found to be dependent on both temperature and frequency.
► The addition of salt has a profound effect on the relaxation rate.