INVESTIGATION ON THE STRUCTURE AND THE CONDUCTIVITY OF PLASTICIZED POLYMER ELECTROLYTES

Electrical properties of polymer electrolytes depend on the structure of polymer matrix. It was reported that transportation of carries in polymer electrolytes was correlated with the segment movement of the amorphous phase. Dynamic property of amorphous phase and the crystallinity of electrolyte would effect the conductivity of polymer electrolytes. The properties of PEO-LiCF3SO3 modified with additives were investigated by conductivity measurement, DSC and H-1-, F-19-NMR experiments. It was found that additives would increase the content of amorphous phase and salt concentration in amorphous phase, and improve the dynamic property of amorphous phase. The spin-spin relaxation time for the polymer matrix is also increased. It was indicated that the glass transition temperature of modified electrolytes was decreased from -21-degrees-C for typical PEO-LiCF3SO3 electrolytes to about -48-degrees-C. These improvements result in the increase of the conductivity.