Polymer electrolyte background

A brief discussion on applying IS to investigate the electrical properties of polymer electrolytes has been dealt with in Chapter 7. This chapter, on the other hand, aims to introduce and provide the necessary background for beginners to use IS as a method of analysis. Thus, we begin the chapter with the definition of impedance, and then discuss the basic principles of IS followed by impedance data presentation and interpretation. Ideal and real impedance data will be presented, compared and discnssed in order to enable the readers to grasp a clearer picture on the electrical properties and electrochemical processes in a polymer electrolyte system. 

The content of the book has three main themes basic principles, design, and analysis. The theme of basic principles provides the necessary background information on the fuel cells, including the fundamental principles such as the electrochemistry, thermod5mamics, and kinetics of fuel cell reactions as well as mass and heat transfer in fuel cells. It also provides an overview of the key principles of the most important types of fuel cells and their related systems and applications. This includes polymer electrolyte membrane fuel... 

Technically, fuel cell research belongs to battery research. Most fuel cell types are run at increased temperamre, hence T is an important parameter [121-143]. On the other hand, nearly all the references cited deal with simple optimisation experiments whereas papers dealing with a fundamental background do not occur frequently [126]. Investigations with cells containing classic, liquid electrolytes are similar to many other classical thermoelectrochemical studies [121-126]. Not very far from classic experiments are fuel cells with polymer electrolyte... 

An alternative method of achieving high ionic conductivity whilst retaining the useful properties of polymer electrolytes in device applications such as lithium batteries, fuel cells, actuators and dye sensitised solar cells, is to use ionic liquids (ILs) either as the main conductivity medium supported in a polymer membrane or as a plasticising component in polymer electrolytes. In this section we provide some background of ILs and their properties in the context of device applications followed by their use in polymer electrolyte systems. 

Capillary sieving electrophoresis (CSE) — An electrophoresis technique, in which analytes are separated in a capillary, containing a sieving medium (e.g., an entangled polymer network) in the -> supporting (background) electrolyte. The separation is based on differences in size and shape of the charged analytes. 

Shibukawa et al. [109] published a new liquid chromatographic method for the determination of acid dissociation constants. On the basis of theoretical equations regarding the effect of background mobile phase ions on the retention of ionic analytes on a non-ionic polymer packing, they could determine simultaneously the dissociation constants (p/fa) and the charges of analyte molecules. They used chloride and perchlorate ions in the mobile phase as they exhibit large differences in the retention on the hydrophilic polymer packings used, so that the effect of the mobile phase electrolyte on the retention factor of an ionic analyte could be clearly evaluated. 

FIG. 6 Initial adsorption rates (dT/dt)0 for the adsorption of various hydrophobi-cally modified carboxypullulans on polystyrene, (o) unmodified OxPu, ( ) OxPu-12/1, ( ) OxPu-12/3, (V) OxPu-12/6 and ( ) OxPu-12/12. Polymer concentration 100 mg L 1, no background electrolyte added. (Adapted from Ref. 25.)... 

The first extrapolation by a square root of concentration in Zr seems to be incorrect, because the ionic strength in these solutions is not affected by the concentration of Zr but by that of the background electrolyte. At constant ionic strength, the dissolution enthalpy should be independent of the Zr concentration. The observed concentration dependeney may indicate a change in solution speciation, hence polymer formation may have occurred. The inclusion of the data of the authors in the overall assessment of Zr hydrolysis requires a re-interpretation of their experimental data in terms of mono-mer/polymer transition. Polymer formation in similar solutions was analysed by [75TRI/SCH]. A re-interpretation was found to be important in similar solutions [75TRI/SCH] (see Appendix A entry) aceording to the reaction ... 

The bands discussed above are again present, although very weak. A distinction between absorption caused by the aniline in solution and the aniline in the polymer is impossible. With the electrolyte solution containing the monomer as a background, a different result is observed. 

Furusawa and Anzai investigated the heterocoagulation of a highly monodisperse amphoteric polymer latex (particle diameter 250 nm, lEP ca. pH 6.8 in 5.0 mM KCl background electrolyte, positively charged at low pH) onto various silica spheres (diameters 240, 460, 960, and 1590nm lEP ca. pH 3.0) dispersed in pure water or upon addition of various hydroxypropyl celluloses (HPCs) [17, 18]. Stable dispersions for both individual particles under the condition that they had opposite... 

Fig. 2 TFFDSEM images of various anionic polymer latexes of different sizes. From left to right poly(vinylidene chloride) latex of 116nm, and polystyrene particles of 180, 320, tind 696 mn in diameter, assembled onto a large cationic polystyrene latex of 2170 nm via heterocoaguladon in 0.5 mM KCl background electrolyte. Images reproduced from Fig. 7 from [20]...

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