Ionically-Conductive Solid Solutions of Divalent Cation Salts in Poly(Ethylene Oxide)

Abstract

Poly(ethylene oxide) (PEO) forms solid solutions with MgCl₂, PbI₂, PbBr₂, and various other salts of divalent cations. DSC analysis and a study of the temperature dependence of conductivity indicate that these materials consist of several crystalline phases, corresponding to pure PEO and salt-rich complexes, and a coexisting elastomeric phase. MgCl₂.(PEO) has an ionic conductivity comparable to that of LiCF₃ SO₃.(PEO) from 10⁻⁵¹⁶ (ohm cm)⁻¹ at 80°C, and the conductivity of PbBr₂.(PEO)₈ is 10⁹⁶ − 10⁻⁷ (ohm cm)⁻¹ at 180°C and about 10⁻⁵ (ohm-cm)⁻¹ at 250°C. The lead halide complexes conduct both Pb²⁺ and halide anions. All of the divalent halide complexes are stable to nearly 300°C.