Ionic Conduction in CNFs Reinforced PMMA Based Nanocomposite Gel Polymer Electrolytes for Li-Ion Batteries

Nanocomposite gel polymer electrolytes are gaining more and more attention among the researchers worldwide due to their possible applications in various electrochemical devices particularly in solid-state Li-ion batteries [1]. In the present work, the effect of carbon nanofibers (CNFs) reinforced in PMMA based gel polymer on the electrical properties has been investigated. The length and outer diameter of CNFs used are in the ranges of 5-50 µm and 200-600 nm, respectively. The electrolytes have been synthesized by solution casting technique with varying the CNFs content. The impedance spectroscopy analysis shows that the incorporation of CNFs into PMMA–(PC+DEC)–LiClO₄gel polymer significantly enhance the ionic conductivity of the electrolyte system. The enhancement of ionic conductivity seems to be correlated with the fact that the dispersion of CNFs to PMMA prevents polymer chain reorganization due to the high aspect ratio of CNFs, resulting in reduction of polymer crystallinity, which gives rise to an increase in ionic conductivity. The decrease of crystallinity of PMMA due the addition of CNFs has been confirmed by X-ray diffraction study. The interaction of CNFs with various constituents of polymer electrolytes has been studied by Fourier transform infrared spectroscopy (FTIR). Transmission electron microscopy (TEM) results show that uniform distribution of CNFs in the polymer electrolytes and FESEM for morphological analysis. Moreover CNFs added gel polymer electrolytes offer better thermal stability as compared to that of electrolytes without CNFs as confirmed by thermal gravimetric analysis (TGA). 

Keywords: Polymer electrolytes; CNFs; Ionic conductivity; XRD; FTIR; TEM; FESEM; TGA.

References

 [1] F.  Croce, G.B.  Appetecchi, L.  Persi, B.  Scrosati, Nanocomposite polymer electrolytes lithium batteries, Nature (London), 394, 456, 1998.