Multinuclear solid-state NMR characterization, ion dissociation, and dynamic properties of lithium-doped organic - Inorganic hybrid electrolytes based on ureasils

Hsien Ming Kao, Tzu Ti Hung, George T.K. Fey

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40 Scopus citations

Abstract

Solid organic - inorganic hybrid electrolytes based on diureasils doped with LiClO4 have been obtained by the sol-gel process through the reaction of poly(propylene glycol)-block-poly(ethylene glycol)block- poly(propylene glycol) bis(2-aminopropyl ether) (H2N - PPG - PEG - PPG - NH2) with 3-isocyanatepropyltriethoxysilane (ICPTES), followed by co-condensation of an epoxy trialkoxysilane, 3-(glycidyloxypropyl) trimethoxylsilane (GLYMO). The structural and dynamic properties of the materials were systematically investigated by a variety of techniques including ac impedance, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), multinuclear (13C, 29Si, 7Li) solid-state NMR, 1H - 13C 2D WISE (wide-line separation) NMR, and 7Li pulsed gradient spin-echo (PGSE) NMR measurements. The length of backbone PEG chain, the extent of GLYMO cross-linking, and the salt concentration were varied in order to obtain the materials with high conductivities. A maximum ionic conductivity value of 1.37 × 10-5 S/cm was obtained at 30°C for the hybrid electrolyte with a [O]/[Li] ratio of 32. This ionic conductivity value is 1 order of magnitude higher than that of previously characterized electrolytes based on ureasils without incorporation of GLYMO. The results of 13C cross-polarization magic-angle spinning (CPMAS) NMR with varying contact times and 1H-13C WISE NMR provided a microscopic view of the effects of salt concentrations on the dynamic behavior of the polymer chains. Only one distinct 7Li local environment was detected by variable temperature 7Li-{1H} MAS NMR. The temperature dependence of 7Li static line widths and self-diffusion coefficients showed that there is a strong correlation between the dynamic properties of the charge carriers and the bulk ionic conductivity.

Original languageEnglish
Pages (from-to)8673-8683
Number of pages11
JournalMacromolecules
Volume40
Issue number24
DOIs
StatePublished - 27 Nov 2007

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