Multinuclear Solid-State NMR Characterization, Ion Dissociation, and Dynamic Properties of Lithium-Doped Organic−Inorganic Hybrid Electrolytes Based on Ureasils

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...