A highly conductive organic-inorganic hybrid electrolyte based on co-condensation of di-ureasil and ethylene glycol-containing alkoxysilane

Organic-inorganic hybrid electrolytes based on di-ureasil backbone structures by reacting poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) bis(2-aminopropyl ether) (ED2000) with 3-(triethoxysilyl) propyl isocyanate (ICPTES), followed by co-condensation with methoxy(polyethylenoxy) propyl trimethoxysilane (MPEOP) in the presence of LiClO4 were prepared and characterized by a variety of techniques. The hybrid electrolytes showed good resistance to crystallization and excellent conductivity for use in lithium-ion batteries, as determined by differential scanning calorimetry (DSC) and impedance measurements, respectively. The temperature dependence of the ionic conductivity exhibited a VTF (Vogel-Tamman-Fulcher)-like behavior for all the compositions studied and a maximum ionic conductivity value of 6.9 x 10(-5) S cm(-1), a relatively high value for solid polymer electrolytes, was achieved at 30 degrees C for the hybrid electrolyte with a [O]/[Li] ratio of 16. A microscopic view of the dynamic behavior of the polymer chains (C-13) and the ionic species (Li-7) was provided by the H-1 and Li-7 line widths measured from 2D H-1-C-13 WISE (Wideline Separation) and variable temperature Li-7 static NMR, respectively, to elucidate the influence of the mobility of the polymer chains and the charge carriers on the observed ionic conductivity. The present salt-free hybrid electrolyte after plasticization with 1M LiClO4 in EC/PC solution exhibited a swelling ratio of 275% and reached an ionic conductivity value up to 8.3 x 10(-3) S cm(-1) at 30 degrees C, which make it a good candidate for the further development of advanced rechargeable lithium-ion batteries. (C) 2009 Published by Elsevier Ltd.