Electrochemical Properties of PEO:LiBF4-Li3N Composite Electrolytes

摘要

A processing technique to produce approx. 100 micrometers thick films ofPEO:LiBF4-Li3N composite electrolyte was developed. The electrochemical properties of the film are found to be sensitive to annealing temperature and time. The ac impedance technique was used to characterize the composite films. At low concentrations of Li3N, the electrolytes exhibited interpretable ac impedance spectra; however, at higher Li3N concentrations the spectra were complex. Nonetheless, the general observation was that the increasing concentration of Li3N increased the conductivity of the composite electrolyte. Annealing the specimens in 125-l40 deg C temperature range yields high conductivity material. The reproductability of the specimen preparation and conductivity data is excellent. Characterization of the specimen using DSC, TGA x-ray diffraction, and infrared spectroscopy reveal that a high temperature (125-145 deg C) annealing leads to formation of a new phase which is believed to be the high conductivity phase. Cyclic voltammograms obtained from the composite electrolyte material reveal these materials are stable when in contact with lithium.