Solid-State NMR, Ionic Conductivity, and Thermal Studies of Lithium-doped Siloxane−Poly(propylene glycol) Organic−Inorganic Nanocomposites

Abstract

Hybrid organic−inorganic ionic conductors, also called ormolytes (organically modified electrolytes), were obtained by dissolution of LiClO4 in siloxane−poly(propylene glycol) matrixes. The dynamic features of these nanocomposites were studied and correlated to their electrical properties. Solid-state nuclear magnetic resonance (NMR) spectroscopy was used to probe the effects of the temperature and nanocomposite composition on the dynamic behaviors of both the ionic species (7Li) and the polymer chains (13C). NMR, dc ionic conductivity, and DSC results demonstrate that the Li+ mobility is strongly assisted by the segmental motion of the polymer chain above its glass transition temperature. The ac ionic conductivity in such composites is explained by use of the random free energy barrier (RFEB) model, which is in agreement with their disordered and heterogeneous structures. These solid ormolytes are transparent and flexible, and they exhibit good ionic conductivity at room temperature (up to 10-4 S/cm). Consequently, they are very promising candidates for use in several applications such as batteries, sensors, and electrochromic and photoelectrochemical devices.