Poly(ethylene oxide) electrolytes containing mixed salts

Abstract

Abstract An unusual conductivity enhancement occurs in PEO‐based ZnBr 2 /LiBr electrolytes of composition, [xZnBr 2 + (1 − x)LiBr](PEO) 16 with x = 0.00, 0.05, 0.50, 0.75, 1.00. The conductivity of the mixed‐salt electrolytes is higher than that of either pure salt electrolyte. The highest conductivity, observed for x = 0.5, is two orders of magnitude higher than that of pure LiBr(PEO) 16 and one order higher than ZnBr 2 (PEO) 16 . In contrast, the conductivity of mixed Mg (CIO 4 ) 2 /LiCIO 4 electrolytes, [ x Mg(CIO 4 ) 2 + (1 − x) LiCIO 4 ](PEO) 16 where x = 0.00, 0.20, 0.50, 0.80, 1.00, increases monotonically with the mole fraction of the higher conductivity component, LiCIO 4 (PEO) 16 . The conductivity and differential scanning calorimetry (DSC) results suggest that the conductivity enhancement in the ZnBr 2 /LiBr electrolytes results from a change in charge carrier type and concentration, whereas the conductivity change in the Mg(CIO 4 ) 2 /LiCIO 4 electrolytes arises from a change in the microscopic viscosity of the electrolytes. © 1993 John Wiley & Sons, Inc.