Effect of Al2O3 nanowires on the electrochemical properties of di-ureasil-based organic–inorganic hybrid electrolytes

Abstract

Organic–inorganic hybrid electrolytes based on the reaction of triblock copolymer poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) bis(2-aminopropyl ether) and 3-(triethoxysilyl)propyl isocyanate doped with lithium trifluoromethanesulfonate and Al2O3 nanowires were synthesized by a sol–gel process. The structural and electrochemical properties of the materials thus obtained were systematically investigated by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry, thermogravimetric analysis, powder X-ray diffraction, 29Si CPMAS (cross-polarization magic angle spinning) NMR, alternate current impedance, and linear sweep voltammetry measurements. FTIR spectra showed the occurrence of complexation and interaction among the components. The maximum ionic conductivity values of 9.8 × 10−5 S cm−1 and 6.8 × 10−4 S cm−1 were obtained at 30 and 75 °C, respectively, for the solid hybrid electrolyte with a [O]/[Li] ratio of 16 and 1 wt% of Al2O3 nanowires. A Vogel–Tamman–Fulcher-like temperature dependence of ionic conductivity was observed for the hybrid electrolytes doped with fillers. The electrochemical stability window of ~4.0 V makes the organic–inorganic hybrid electrolyte promising for lithium-ion battery application at low voltages.