Studies on plasticized PEO–lithium triflate–ceramic filler composite electrolyte system

Composite polymer electrolytes (CPEs), polyethylene oxide (PEO)+Li triflate with Li Nasicompound [Li1.4(Al0.4Ge1.6)(PO4)3] as the ceramic filler and EC+PC as the plasticizer, have been studied as thin films. Their crystallinity, thermal behaviour, mechanical strength, ionic conductivity, interfacial stability and Li(1s) XPS binding energies (BEs) have been examined. Changes in Tg, melting temperatures (Tm1 and Tm2), tensile strength (TS) and maximum elongation at break of the CPE films have been studied as a function of different wt.% plasticizer. With the addition of plasticizer, an order of magnitude increase in the ionic conductivity was obtained for temperature T<60 °C. The σ−T data of the CPEs have been fitted to either Arrhenius-type or Vogel–Tamman–Fulcher (VTF)-type behaviour depending on the T range and plasticizer content. Interfacial stability was found to be enhanced with the addition of plasticizer. The variation in the Li(1s) binding energies correlates well with that of σ values. Present study shows that CPEs with 5–10 wt.% plasticizer exhibit the optimum performance.