Polymer electrolyte relaxation processes

In 1983 he joined the editorial board of Polymer, of which he thrar became main editor, and is also on the editorial boards of Journal of Applied Polymer Science, Polymer Contents, Polymers for Advanced Technologies, Korean Polymer Journal, and Trends in Polymer Science. He was awarded a D.Sc. from the Urriversity of Edinbtrrgh for Research Work on the hydrodynamics of polymCT solutiorrs, studies of relaxation processes in the glassy state of polymers, and on physical characterization of polymers. His crrrrent interests are centered on phase eqtrihbria in polymer blends, polymer hqtrid crystals, ion conduction in polymCT electrolytes, physical aging, and hqtrid crystalhne celltrlose/polymer blends and composites. 

A review of field quantities and formal results is followed by discussion of equilibrium theories and simulations for polar liquids. Relaxation processes are considered primarily in terms of correlation function treatments starting with models of behavior in simple systems and going on to cooperative behavior in more complex systems as a function of temperature with some reference to polymers and molecular crystals. Other aspects discussed include correlation functions from transient birefringence ion-solvent interaction effects in electrolytes and relaxation in mixtures of polar liquids. 

Higher-density currents result in water mass-transport limitations and the appearance of additional low-frequency impedance relaxation. This diffusion impedance due to water transport within the polymer electrolyte morphology is often represented by the finite diffusion processes affecting both the anodic (Zq ) and cathodic (Z ) processes (Figure 12-16B). An increase in anodic impedance is often related to partial drying out of the anode/membrane interface. 

The foregoing results at first seem to be rather peculiar when one realizes that the volume of carrier ion may be far smaller than that of the moving unit of polymer chain involved in the relaxation process. This may seem more reasonable when one considers that the ionic transport in a polymer electrolytes does not occur by itself, but that the segmental motion with associated carrier ions causes the ionic transport. In other words, ions in the polymers are solvated by the polymer chain, and these solvated ions move by the assistance of the segmental motion. 

Another important merit of the in situ gellification , rarely mentioned by various authors in the literature, is that the limitation on electrolyte composition can be relaxed. In the traditional process of making a GPE, the liquid electrolyte has to be heated with the polymer host to form the gel, during which the thermal instability of the lithium salt (LiPFe or LiBF4) and the volatility of the solvents (DMC, EMC, etc) could possibly cause the resultant GPE to deviate from the desired composition or even to degrade. It is for this reason that in most of the literature on GPE the liquid electrolytes have to be based on Lilm, LiBeti as salts, and EC/PC as solvents. In Bellcore technology, on the contrary, the state-of-the-art electrolytes, the typical of which is LiPFe/EC/DMC, could be used, since gellification occurs only after the cells are assembled. ... 

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