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

Abstract

Composite polymer electrolytes (CPEs), polyethylene oxide (PEO)+Li triflate with Li Nasicompound [Li_1.4(Al_0.4Ge_1.6)(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 T_g, melting temperatures (T_m1 and T_m2), 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.