A single ion-conducting polymer electrolyte based on PEO and anionic nanoparticles: electrical and NMR characterization

We report on electrical properties of fluorine-functionalized nanoscopicTiO2and its reaction with molten Li, which produces a single ion Li conductor. It is believed that the fluorines and the lithiums are concentrated in a 2-4 nm shell around the TiO2 core, based on XRD and vibrational spectroscopic evidence.Mixing this material with PEO results in a polymer electrolyte with favorable mechanical as well as electrical properties. For example, a sample containing ~10 wt% PEO demonstrates an ionic conductivity of 1.5 x 10-5 S/cm at 20oC and 1.0 x 10-4 S/cm at 80oC, with a Li+ transference number of unity. Additional characterization, including electrochemical stability window, exchange current density, and variable temperature broadband electrical spectroscopy (covering a frequency range of 10-2 to 107 Hz) Multinuclear (1H, 7Li and 19F) solid state NMR measurements, including spectra, relaxation, and transport as a function of PEO/TiO2:F,Li ratio will be presented.