Enhanced ionic conductivity in nano-composite solid polymer electrolyte: (PEG) x LiBr: y(SiO2)

Abstract

In this paper, we report an enhancement in ionic conductivity in a new nano-composite solid polymer electrolyte namely, (PEG) x LiBr: y(SiO2). The samples were prepared, characterized, and investigated by XRD, IR, NMR, and impedance spectroscopy. Conductivity as a function of salt concentration shows a double peak. Five weight percent addition of silica nanoparticles increases the ionic conductivity by two orders of magnitude. Conductivity exhibits an Arrhenius type dependence on temperature. IR study has shown that the existence of nanoparticles in the vicinity of terminal O―H group results in a shift in IR absorption frequency and increase in amplitude of vibration of the terminal O―H group. This might lead to an enhancement in conductivity due to increased segmental motion of the polymer. 7Li NMR spectroscopic studies also seem to support this. Thus addition of nanoparticle inert fillers still seems to be a promising technique to enhance the ionic conductivity in solid polymer electrolytes.