Evaluation of doped polyethylene oxide as solid electrolyte

A study correlating electrical properties (a.c. conductivity and permittivity) to changes in the polymer morphology of polyethylene oxide (PEO) doped with lithium tetrafluoroborate (LiBF"4) was investigated. A TA Instruments Dielectric Analyzer, DEA 2970, was used to measure electrical properti...
Ausführliche Beschreibung

A study correlating electrical properties (a.c. conductivity and permittivity) to changes in the polymer morphology of polyethylene oxide (PEO) doped with lithium tetrafluoroborate (LiBF"4) was investigated. A TA Instruments Dielectric Analyzer, DEA 2970, was used to measure electrical properties. The morphological changes were traced via differential scanning calorimetry (DSC), thermogravimetry (TG), and Fourier transform infrared spectroscopy (FTIR).The study showed that the relationship between dopant concentration and morphological changes of the polymer is rather complex. A reduction of crystallinity at low dopant concentration, phase separation involving ion-polymer complexes at high concentration, and formation of neutral ion pairs at very high ion concentration are the proposed mechanisms to explain the conductivity data. The dissociation of ions, changes in viscosity, and their effect on ion mobility were also considered to explain conductivity and permittivity data.The advantages and limitations of the DEA 2970 for measuring the ionic conductivity of polymeric electrolytes are discussed. Ausführliche Beschreibung