Alternating current conductivity and electrical conductivity relaxation in an intercalated polymer electrolyte

Abstract

Sodium cations solvated by polyethylene oxide have been confined by intercalation in the interlamellar space of an insulating layered solid, CdPS₃. The frequency-dependent conductivity and the associated conductivity relaxation in the intercalated polymer electrolyte have been investigated. The temperature-dependent conductivity displays a distinct change in behavior at T ~225 K. Below 225 K the dc conductivity, σ_dc, shows an Arrhenius temperature dependence, while for T>225 K σ_dc rises sharply and follows the Vogel-Tamann-Fulcher relation, characteristic of ionic motion coupled to polymer relaxation modes. An analysis of the frequency-dependent conductivity using the electrical modulus representation showed that the electrical conductivity relaxation may be described in terms of the stretched exponential correlation function in the time domain, Φ(t) = exp(-t/τ_σ)^β. The absence of any anionic contribution to the electrical response makes these intercalated polymer electrolyte systems attractive for fundamental studies on ionic motion in disordered polymeric media.