a1 Centre for Ionics University Malaya, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
a2 Centre for Surface Chemistry and Catalysis, Faculty of Bioengineering Science, Katholieke Universiteit Leuven, 3001 Leuven, Belgium
Solid polymer electrolytes (SPEs) with poly(vinylidene fluoride-hexafluoropropylene) [P(VdF-HFP)] as polymer host, doped with magnesium trifluoromethanesulfonate (MgTf) and 1-butyl-3-methylimidazolium trifluoromethanesulfonate (BMIMTf) have been synthesized via solution casting method. This P(VdF-HFP)/MgTf/BMIMTf-based SPE achieves ∼3 × 10−3 and ∼7 × 10−3 S·cm−1 at 30 and 80 °C, respectively, with 75 part by weight (pbw) of BMIMTf. At the same time, they are also examined by means of frequency-dependent conductivity, dielectric permittivity, and dielectric modulus studies. Scanning electron microscopy reveals drastic morphological changes on SPE with small amount of BMIMTf. Even though it gradually changes back to its undoped state with higher concentration, it appears to be swollen. Examination on relationship between ionic conductivity and crystallinity by differential scanning calorimetry technique shows inconsistency at concentration higher than 75 pbw. This observation is related to greater ion–ion interaction due to excessive BMIMTf. Photoluminescence is also used to detect structural alterations in the local environment of SPE.
(Received December 05 2011)
(Accepted February 08 2012)