Abstract
Two series of hybrid inorganic–organic polymer electrolytes of the organically modified ceramics as polymer electrolytes (ORMOCERS-APE) type with formulas {Al[O(CH 2CH 2O) 8.7] ρ /(LiClO 4) z } n (1.85 ≤ ρ ≤ 2.24, 0 ≤ z ≤ 1.06) and {Zr[O(CH 2CH 2O) 8.7] ρ /(LiClO 4) z } n (1.80 ≤ ρ ≤ 1.99, 0 ≤ z ≤ 0.90) were treated with CO 2 in subcritical conditions (293 K and 5 MPa). The effect of CO 2 on the samples was investigated by using ESEM, thermal analysis (TG and DSC) and broad band dielectric spectroscopy (BDS). Both complexes {Al[O(CH 2CH 2O) 8.7] ρ /(LiClO 4) z } n and {Zr[O(CH 2CH 2O) 8.7] ρ /(LiClO 4) z } n after CO 2 treatment exhibited a change in the segmental relaxation with respect to the untreated samples. This phenomenon has been interpreted in terms of higher portion of free volume in the samples. The CO 2 treatment primarily lowered the conductivity of {Al[O(CH 2CH 2O) 8.7] ρ /(LiClO 4) z } n complexes of about one order of magnitude, as opposed to {Zr[O(CH 2CH 2O) 8.7] ρ /(LiClO 4) z } n complexes, where an increment of two orders of magnitude was observed. In both cases the conductivity of the treated and untreated materials versus the reciprocal absolute temperature presents the typical Vogel–Tamman–Fulcher (VTF) behavior. The different effects on the conductivities of the treated complexes are explained in terms of the modified anion-trapping ability of Al centers and in terms of the interactions of subcritical CO 2 with the host polymer and the salt. Insight about the conductivity mechanisms were provided by the study of the VTF parameters and the relaxation times determined from the Debye peaks of the imaginary resistivity, the imaginary permittivity and the correlated motion analysis.
Published Version
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