Ionic transport, thermal, XRD, and phase morphological studies on LiCF3SO3-based PVC–PVdF gel electrolytes

摘要

The plasticized polymer electrolyte composed of polyvinylchloride (PVC) and polyvinylidene fluoride (PVdF) as host polymer, the mixture of ethylene carbonate and propylene carbonate as plasticizer, and LiCF3SO3 as a salt was studied. The effect of the PVC-to-PVdF blend ratio with the fixed plasticizer and salt content on the ionic conduction was investigated. The electrolyte films reveal a phase-separated morphology due to immiscibility of the PVC with plasticizer. Among the three blend ratios studied, 3:7 PVC–PVdF blend ratio has shown enhanced ionic conductivity of 1.47 × 10?5 S cm?1 at ambient temperature, i.e., the ionic conductivity decreased with increasing PVC-to-PVdF ratio and increased with increasing temperature. A temperature dependency on ionic conductivity obeys the Arrhenius behavior. The melting endotherms corresponding to vinylidene (VdF) crystalline phases are observed in thermal analysis. Thermal study reveals the different levels of uptake of plasticizer by VdF crystallites. The decrease in amorphousity with increase in PVC in X-ray diffraction studies and larger pore size appearance for higher content of PVC in scanning electron microscopy images support the ionic conductivity variations with increase in blend ratios.