A Sol-Gel Solid Electrolyte with High Lithium Ion Conductivity

A new hybrid inorganic gel electrolyte has been synthesized by the sol−gel method. The inorganic gel electrolyte is based on the immobilization of a liquid electrolyte in an inorganic silica network. The former is responsible for ionic conduction, while the latter provides a three-dimensional microporous environment to support the liquid electrolyte. The synthesis involves mixing equal amounts by weight of a hydrolyzed silica precursor and a lithium ion conducting liquid electrolyte. The conductivity of the partially dried gel is 3.5 × 10 - 3 S cm - 1 at room temperature and approaches 10 - 2 S cm - 1 at 80 °C. The temperature dependence of the conductivity follows an Arrhenius relation with an activation energy of 0.15−0.17 eV over the temperature range 30−80 °C. NMR data confirm the lithium ion mobility and show its liquidlike behavior over this temperature range. TGA and DSC results indicate that the inorganic gel electrolyte is stable to 90 °C and that the thermal stability is simply limited by the liquid electrolyte. FT-IR and mass spectrometry establish that there is no water present in the dried material.