Ion transport studies in nanocomposite polymer electrolyte membrane of PVA-[C(4)C(1)Im][HSO4]-SiO2

摘要

The paper reports the effect of SiO2 nano-filler on structural, thermal, and ion transport properties of polymer electrolyte system comprising polyvinyl alcohol (PVA) and 1-butyl-3-methylimidazolium hydrogen sulfate [C(4)C(1)Im][HSO4] ionic liquid. The addition of SiO2 nano-filler results into enhancement in amorphicity and thermal stability and lowering of glass transition temperature of the membranes. A detailed investigation of possible interactions among the constituents PVA, [C(4)C(1)Im][HSO4] and SiO2, and cation-anion and anion-anion pairs of [C(4)C(1)Im][HSO4] in the polymer electrolyte and their dissociation due to SiO2 filler has been carried out in the membranes using Fourier transform infra-red (FTIR) and Raman spectroscopy. The membranes show maximum room temperature ionic conductivity as 9.9 x 10(-3) S cm(-1) for 6 wt.% of the nano-filler which is about four times higher than the membrane without nano-filler and an order higher than pure [C(4)C(1)Im][HSO4]. With temperature, the ionic conductivity shows VTF behavior in the temperature range 40-120 A degrees C. On the basis of FTIR and ion transport results, a model for ion transport in the membranes is proposed.