The role of zirconium oxide as nano-filler on the conductivity, morphology, and thermal stability of poly(methyl methacrylate)-poly(styrene-co-acrylonitrile)-based plasticized composite solid polymer electrolytes

摘要

The plasticized composite solid polymer electrolytes (CSPE) involving polymer blends poly(methyl methacrylate)-poly(styrene-co-acrylonitrile) (PMMA-SAN), plasticizers ethylene carbonate (EC), and propylene carbonate (PC) with lithium triflate (LiCF3SO3) as salt and varying concentration of composite nano-filler zirconium oxide (ZrO2) is prepared by solution casting technique using THF as solvent. The powder X-ray diffraction (XRD) studies reveal amorphous nature of the CSPE samples. Fourier transform infrared (FT-IR) spectroscopy studies reveal interaction of Li+ ion with plasticizers, both C=O and OCH3 group of the PMMA, while nitrile group of SAN is inert. AC impedance and dielectric studies reveal that the ionic conductivity (sigma), dielectric constant (epsilon'), and dielectric loss (epsilon) of the prepared CSPE samples increase with increasing content of ZrO2 nano-filler up to 6wt% and decrease with further additions. The temperature dependence of ionic conductivity follows Arrhenius relation and indicates ion-hopping mechanism. The sample Z2 (6wt% ZrO2) with relaxation time of 8.13x10(-7)s possess lowest activation energy (E-a=0.23eV) and highest conductivity (2.32x10(-4)Scm(-1)) at room temperature. Thermogravimetric analysis (TGA) reveals thermal stability of highest conducting sample Z2 up to 321 degrees C after complete removal of residual solvent, moisture, and its impurities. Differential scanning calorimetric (DSC) studies reveal absence of glass transition temperature (T-g) corresponding to atactic PMMA for the CSPE Z2, while isotactic PMMA component shows T-g around 70 degrees C, which is due to increased interaction of filler with PMMA leading to change in its tacticity. Scanning electron microscopy (SEM) analysis reveals blending of PMMA/SAN polymers and lithium triflate salt. The incorporation of nano-filler ZrO2 leads to change in surface topology of polymer matrix. Rough surface of the CSPE Z2 leads to new pathway for ionic conduction leading to maximum ionic conductivity.