Evaluation of Doped Polyethylene Oxide as Solid Electrolyte for Polymer Batteries.

摘要

This report presents results of an investigation on preparation and characterization of polyethylene oxide (PEO) and lithium tetrafluoroborate (LiBF4) complexes for application as solid electrolytes in polymer batteries. AC conductivity and permittivity (dielectric constant) as a function of frequency, temperature, and concentration of lithium tetrafluoroborate (LiBF4) in polyethylene oxide (PEO) films were measured with a TA Instruments DEA 2970, Dielectric Analyzer. Differential Scanning Calorimetry (DSC) was used to trace changes of the morphology of the polymeric medium. Thermogravimetry (TG)/derivative thermogravimetry (DTG) were used to follow the decomposition of components and define the maximum temperature limits for these measurements. Infrared Spectroscopy monitored structural evolution as the O:Li ratio in the polymer complex was varied. Thin films of a complex (O:Li = 8) were used to assemble Li/Polymer/Li Cell for electrochemical characterization. The study showed that the relationship of dopant concentration to electrical properties is rather complex. Degree of ion-pairing, dissociation of ions on dilution, changes in the morphology of the polymeric medium, and variations in viscosity and its consequence on ion mobility were considered to explain the data. An optimum in room conductivity occurred in a complex with O:Li ratio of 8.