Dielectric and conductivity relaxation in poly(propylene glycol)–lithium triflate complexes

Abstract

The electric modulus representation is used to display conductivity and dielectric relaxation occurring in poly(propylene glycol)-4000 (PPG) complexed with LiCF3SO3, as the ether oxygen to lithium (O:Li) ratio is varied from 300:1 to 12:1. The frequency range covered is 10 to 107 Hz. Results are obtained for temperatures above the glass transition temperature appropriate for each PPG–LiCF3SO3 complex. For O:M=300:1, the conductivity peak and the α and α′ relaxation are clearly resolved. As the concentration is increased, there is a coupling between the structural and the conductivity relaxations; the various peaks begin to overlap. The coupling is greatest for an O:Li ratio in the range 30:1 to 12:1, where the highest conductivity is measured. Below room temperature, the 30:1 complex has the highest conductivity, above room temperature the 12:1 complex has the highest. At any particular temperature there is a concentration above which the conductivity drops. This drop is due to reduced ion mobility resulting from a dramatic increase in viscosity to values above ∼100 poise.

Studies of structural, thermal and electrical behavior of polymer nanocomposite electrolytes

“…This suggests that ionic motion and polymer segmental motion are strongly coupled manifesting as peak in the M″ spectra with no corresponding feature in dielectric spectra [35]. Similar results have been reported by Fu et al [34] for PPG-LiCF 3 SO 3 system with higher salt concen- . So the conduction in polymer electrolytes takes place through charge migration of ions between coordinated sites of the polymer along with its segmental relaxation.…”

“…Motion of the other ions in this region will be affected by perturb potential. Such a cooperative motion of ions will lead to non-exponential decay, or a conduction processes with distribution of relaxation time [34].…”

Polymers with Ionic Liquid Fragments as Potential Conducting Materials for Advanced Applications

“…The intensity of the modulus relaxation peak is 0.18, 0.19, 0.16, 0.23, 0.22 and 0.15, for KN5, KN6, KN7, KN8, KN9 and KN10, respectively; whereas no peak is observed in the dielectric spectra. Similar results have been reported by Fu et al 47 for PPG-LiCF 3 SO 3 s y s t e m w i t h h i g h e r s a l t c o n c e n t r a t i o n . S o t h e c o n d u c t i o n i n p o l y m e r electrolytes takes place through charge migration of ions between coordinated sites of the polymer along with its segmental relaxation.…”

New APTES Cross-Linked Polymers from Poly(ethylene oxide)s and Cyanuric Chloride for Lithium Batteries

“…2 However, at temperatures below 80°C, PEO films tend to crystallize, dramatically decreasing conductivity. [3][4] Furthermore, for many battery applications even high molecular weight PEO has unacceptable mechanical properties, especially at higher temperatures.…”