Preparation and Characterization of PVDF-MG49-NH4CF3SO3 Based Solid Polymer Electrolyte

The ionic conductivity of ammonium-based solid polymer films of poly(vinylidene fluoride) (PVDF) blended with MG49, a graft of natural rubber and poly(methyl methacrylate), with various compositions of ammonium triflate NH4CF3SO3, was investigated. As a result, 30 wt.% of NH4CF3SO3-doped polymer electrolyte exhibits the highest ionic conductivity at 6.32×10-4 S/cm at room temperature. The conductivity enhancement can be attributed to the increase in the number of NH4+ as charge carriers. The significance of the blend is the increase of one order in ionic conductivity as compared with pure PVDF electrolyte. The temperature dependence of conductivity of the electrolyte does not obey the Arrhenius law. However, the conductivity increases with temperature and it reached 1.56×10-3 S/cm at 363 K. X-ray diffraction reveals a decrease in crystallinity of the electrolyte upon the addition of NH4CF3SO3 salt. This result is supported by scanning electron microscopy. Linear sweep voltammetry demonstrates that the anodic stability of the electrolyte is up to 4 V. Therefore, the electrolyte shows good compatibility with high-voltage electrode. Hence, this electrolyte system can be a prospective candidate as lithium-ion conducting electrolyte for lithium batteries.