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) have been prepared by using LiClO4 and LiN(CF3SO2)2 as the doping salts, and nanoscale SiO2 as the filler. The samples have been characterized for what concerns their thermal and transport properties. The addition of the filler determines an increase of the conductivity of more than one order-of-magnitude, depending on the filler concentration. The maximum value of 1.4×10−4 ohm−1 cm−1 is obtained for the sample PEO8–LiN(CF3SO2)2–5 wt% SiO2. Effects of the silica thermal history on the conductivity level have been also ascertained. The cation transport number, t+, changes from ~0.1 to ~0.2 when 10 wt% of filler is added.