Characterization of ionic conducting cross-linked polyether electrolytes

Abstract

An appropriate amount of toluene 2,4-diisocyanate (TDI) was added into polyether ([(CH₂ CH₂O)₁₃CH₂O]n)]Li salt electrolyte to form a cross-linked network, with improving the film processability and thermal stability. The relation between the structure and ionic conductive properties of the cross-lined polyether electrolytes was investigated by means of Fourier transform infra-red spectroscopy (FTIR), differential scanning calorimetry (DSC), mechanical property and AC impedance spectroscopy. The electrolytes system is found to have two glass transitions, and it is found that the two T_gs increase with increasing salt concentration. At the same Li salt concentration, the conductivity of cross-linked polyether/LiN(CF₃SO₂)₂ complex system is higher than that of LiClO₄. At EO/Li=25∶1(mol ratio), the former conductivity changes with temperature, while the later coincids with Arrhenius formula (σ=Ae^−EalRT). The cross-linked polyether/LiN(CF₃SO₂)₂ electrolyte exhibits the maximum σ=10^−4.75 S/cm at 30°C.

Keywords

cross-linked / polymer electrolyte / ionic conductivity / two glass transitions

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