Mechanical and thermal characteristics of PMMA-based nanocomposite gel polymer electrolytes with CNFs dispersion

Abstract

The effect of dispersion of carbon nanofibers (CNFs) in poly methyl methacrylate-based gel polymer electrolytes PMMA-(PC+DEC)-LiClO4 on the ionic, thermal and mechanical characteristics has been investigated. The electrolytes have been synthesized by solution casting technique with the various dispersoid contents of 0.5, 1.0, 1.5 and 2.0wt.%. The impedance spectroscopic analysis of the samples shows that the dispersed electrolytes have higher ionic conductivities than the dispersoid free electrolyte. The enhanced ionic conductivity of the dispersed electrolytes is perhaps due to the fact that CNFs having larger aspect ratio prevents polymer chain reorganization resulting in reduced crystallinity. The larger amorphous region of the polymer leads to higher ionic conductivity. The maximum conductivity (0.39×10−4 Scm−1) at room temperature (30°C) is resulted for the electrolyte with 2.0wt.% dispersoid and the temperature dependent conductivity of the sample follows Vogel–Tamman–Fulcher (VTF) relationship. The samples have been characterized by various analytical techniques such as X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis. Stress–strain characteristics of the electrolytes were investigated. The degree of crystallinity of the electrolyte samples has been assessed by X-ray diffraction (XRD) analysis. The complexation of the salt and the interaction of CNFs with polymer in the synthesized electrolyte have been investigated by FTIR analysis. Improvement in thermal stability of the dispersed electrolytes has been demonstrated by TGA. Enhanced tensile strength for the electrolyte with 2wt.% dispersoid was found.