Composite polymer electrolytes electrochemical performance

Song, M. K., Kim, Y. T. and Rhee, H. W. 2001. Composite polymer electrolyte membranes for high PEMFC performance. Proceedings of Electrochemical Society Meeting, San Francisco, CA. 

In the 1980s, several authors proposed the use of composite polymer electrolytes. The solutions they proposed depended on the electrochemical application, i.e. lithium batteries, fuel cells, etc., which determined the properties required. This chapter reviews the development and properties of composite polymer electrolytes used in lithium batteries and proton exchange membrane fuel cells (PEMFC). The effects of fillers on electrolyte properties are discussed in terms of electrochemical performance, and also in terms of polymer matrix morphology and dynamics. Data from the literature are compared in order to determine the effects of the manufacturing... 

Skotheim et al. [286, 357, 362] have performed in situ electrochemistry and XPS measurements using a solid polymer electrolyte (based on poly (ethylene oxide) (PEO) [363]), which provides a large window of electrochemical stability and overcomes many of the problems associated with UHV electrochemistrty. The use of PEO as an electrolyte has also been investigated by Prosperi et al. [364] who found slow diffusion of the dopant at room temperature as would be expected, and Watanabe et al. have also produced polypyrrole/solid polymer electrolyte composites [365], The electrochemistry of chemically prepared polypyrrole powders has also been investigated using carbon paste electrodes [356, 366] with similar results to those found for electrochemically-prepared material. 

Kamarajugadda, S., and Mazumder, S. Numerical investigation of the effect of cathode catalyst layer structure and composition on polymer electrolyte membrane fuel cell performance. Journal of Power Sources 2008 183 629-642. Krishnan, L., Morris, E. A., and Eisman, G. A. Pt black polymer electrolyte-based membrane-based electrode revisited. Journal of the Electrochemical Society 2008 155 B869-B876. 

The main difference between the AFC and PAFC is the gas-tight solid polymer electrolyte membrane, a sohd proton exchange membrane which has as its main function the transport of protons from anode to cathode. To investigate the physical and electrochemical origins of the performance loss in PEFC—operated at different conditions like high current densities, fuel composition (neat H2, H2 -1- lOOppm CO, H2O), flow rates, temperature, air or pure oxygen, etc.—electrochemical impedance studies on different PEFC systems with different electrodes and membranes were performed, as mentioned in Section 4.5.4.1. First impedance measurements and interpretation of FIS performed to characterize PEFC were reported by Srinivasan et al. [1988], Fletcher [1992], Wilson et al. [1993] and Poltarzewski et al. [1992], With increasing research and development effort to improve the PEFC performance and availability of suitable instrumentation the number of publications has increased. 

Jo et al prepared and characterised Gel polymer electrolytes composed of methy methacrylete-styrene copolymers (PMS) and electrolyte solution (LiT-FSI in EC/DMQ. Depending on the molar composition of the copolymer, these gel polymer electrolytes exhibited different electrochemical and mechanical properties. In order to investigate the physical interactions among organic solvents, polymer, and lithium ions occurred in the gel polymer electrolyte, Raman spectroscopy and solid state Li NMR spin-spin relaxation measurements were performed. 

Abstract This chapter details the preparation and mechanism of polymer electrolytes and their applications in electrochemical fields, such as lithium ion batteries, fuel cells, alkahne batteries, supercapacitors, solar cells, electrochromic devices and the like. Polymer electrolytes used in lithium ion batteries are divided into three categories solid, gel and composites. Recent progress made in these three categories is highlighted. Moreover, in addition to the lithium ion battery, appUcations of polymer electrolytes in other electrochemical fields and their ion conducting performance are also briefly described. 

The speed of p- and n-type doping and that of p-n junction formation depend on the ionic conductivity of the solid electrolyte. Because of the generally nonpolar characteristics of luminescent polymers like PPV, and the polar characteristics of solid electrolytes, the two components within the electroactive layer will phase separate. Thus, the speed of the electrochemical doping and the local densities of electrochemically generated p- and n-type carriers will depend on the diffusion of the counterions from the electrolyte into the luminescent semiconducting polymer. As a result, the response time and the characteristic performance of the LEC device will highly depend on the ionic conductivity of the solid electrolyte and the morphology and microstructure of the composite. 

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