Effects of nanoscale SiO2 on the thermal and transport properties of solvent-free, poly(ethylene oxide) (PEO)-based polymer electrolytes

Solvent-free, composite electrolytes based on poly(ethylene oxide) (PEO) ha ve been prepared by using LiClO4 and LiN(CF3SO2)(2) as the doping salts, an d nanoscale SiO2 as the filler. The samples have been characterized for wha t concerns their thermal and transport properties. The addition of the fill er determines an increase of the conductivity of more than one order-of-mag nitude, depending on the filler concentration. The maximum value of 1.4 x 1 0(-4) ohm(-1) cm(-1) is obtained for the sample PEO8-LiN(CF3SO2)(2)-5 wt% S iO2. Effects of the silica thermal history on the conductivity level have b een also ascertained. The cation transport number, t(+), changes from simil ar to 0.1 to similar to 0.2 when 10 wt% of filler is added. (C) 1999 Publis hed by Elsevier Science B.V. All rights reserved.