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 x 10(-3) S cm(-1) at room temperature and approaches 10(-2) S cm(-1) at 80 degrees 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 degrees 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 degrees 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.