Ionic conductivity in crystalline–amorphous polymer electrolytes – P(EO)6:LiX phases

Recent reports have indicated higher ionic conductivities in crystalline polymer electrolytes consisting of isostructural P(EO)6:LiX (X=PF6, AsF6, SbF6) phases relative to the analogous amorphous materials. These reports challenge the conventional wisdom in polymer electrolyte research that amorphous electrolytes are much more conductive than crystalline ones. The higher conductivity in the crystalline materials was attributed to the structures in which Li+ cations are located within PEO cylinders uncoordinated by the anions. The conductivity and crystallinity of P(EO)n–LiClO4 (EO/Li=6 and 10) electrolytes have been examined here. In contrast to the recent reports, much lower conductivities are found for the isostructural P(EO)6:LiClO4 crystalline electrolyte relative to the same fully amorphous electrolyte. [Copyright &y& Elsevier]