Solid polymer electrolytes VIII: effect of LiClO4-doped level on the microstructure and ionic conductivity of a chemical-covalently polyether-siloxane hybrid electrolyte

A new hybrid polymer electrolyte system based on chemical-covalently polyether and siloxane phases is designed and prepared in the presence of lithium perchlorate (LiClO₄) which acted as both ionic source and the epoxide ring-opening catalyst. The effect of salt-doped level on the microstructure and ionic conductivity of these composite electrolytes were investigated by means of Fourier transform infra-red spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis, a.c. impedance and multinuclear solid-state nuclear magnetic resonance measurements. DSC results indicate that the formation of transient cross-links between Li⁺ ions and the ether oxygens on complexation with LiClO₄ results in an increase in polyether segment T_g. However, the polyether segment T_g decreases at the highest salt concentration (5.0 mmol LiClO₄/g PEGDE), ascribing to the plasticizing effect. The behavior of ion transport is coupled with the segmental motions of polymer chains and also correlated with the interactions between ions and polymer host.