Fuel cells, 26-27, Chapter applications

Abstract The scope of this chapter is to give a brief introduction about fuel cells, types of applications in fuel cell technology, characteristics of fuel cells, potential applications in fuel cell technology, and current research and development and key technology players in fuel cells. 

Abstract To date, microcalorimetry of CO adsorption onto supported metal catalysts was mainly used to study the effects induced by the nature and the particle size of supported metallic clusters, the conditions of pretreatment and the support materials on the surface properties of the supported metallic particles. The present chapter focuses on the employ of adsorption microcalorimetry for studying the interaction of carbon monoxide with platinum-based catalyst aimed to be used in proton exchange membrane fuel cells (PEMFCs) applications. 

Chapter 3 discusses solid electrolytes and some of their early applications in fuel cells and catalysis. This material is quite familiar to the solid state ionics community but may be helpful to surface scientists, aqueous electrochemists and chemical reaction engineers. 

At present, intercalation compounds are used widely in various electrochemical devices (batteries, fuel cells, electrochromic devices, etc.). At the same time, many fundamental problems in this field do not yet have an explanation (e.g., the influence of ion solvation, the influence of defects in the host structure and/or in the host stoichiometry on the kinetic and thermodynamic properties of intercalation compounds). Optimization of the host stoichiometry of high-voltage intercalation compounds into oxide host materials is of prime importance for their practical application. Intercalation processes into organic polymer host materials are discussed in Chapter 26. 

Typical chemical stractures of ion-exchange membranes for technical applications are shown in Fig. 26.3. Judging superficially, they may look somehow similar, but structural details do lead to important differences in behavior and performance. Membrane fuel cells are discussed in detail in Chapter 20. 

The catalytic applications of Moiseev s giant cationic palladium clusters have extensively been reviewed by Finke et al. [167], In a recent review chapter we have outlined the potential of surfactant-stabilized nanocolloids in the different fields of catalysis [53]. Our three-step precursor concept for the manufacture of heterogeneous egg-shell - nanocatalysts catalysts based on surfactant-stabilized organosols or hydrosols was developed in the 1990s [173-177] and has been fully elaborated in recent time as a standard procedure for the manufacture of egg-shell - nanometal catalysts, namely for the preparation of high-performance fuel cell catalysts. For details consult the following Refs. [53,181,387]. 

Ukraine s Y. Maletin et al. presented a comprehensive overview describing state of the art as well as future development trends in supercapacitors, as the fifth paper in this chapter. The authors establish key performance bars for supecapacitors upon meeting those, supercapacitors may start to compete with batteries. Also, this paper highlights so-called hybrid applications where supercapacitors complement operation of batteries and/or fuel cells. Optimization of supercapacitor performance through varying electrode thickness is contemplated in length. 

The discussion of Brouwer diagrams in this and the previous chapter make it clear that nonstoichiometric solids have an ionic and electronic component to the defect structure. In many solids one or the other of these dominates conductivity, so that materials can be loosely classified as insulators and ionic conductors or semiconductors with electronic conductivity. However, from a device point of view, especially for applications in fuel cells, batteries, electrochromic devices, and membranes for gas separation or hydrocarbon oxidation, there is considerable interest in materials in which the ionic and electronic contributions to the total conductivity are roughly equal. 

Summarizing progress in the field thus far, the book describes current materials, future advances in materials, and significant technical problems that remain unresolved. The first three chapters explore materials for the electrochemical cell electrolytes, anodes, and cathodes. The next two chapters discuss interconnects and sealants, which are two supporting components of the fuel cell stack. The final chapter addresses the various issues involved in materials processing for SOFC applications, such as the microstructure of the component layers and the processing methods used to fabricate the microstructure. 

Looking at the transport application and the concerns of automotive technicians, interest is still restricted. One reason is that fuel-cell vehicles are not yet ready for marketing. The market introduction scenarios are shown in Chapter 14. Another reason is that the biggest share of the automotive turnover comes from buying and selling vehicles (82%) and not from maintenance and repair. In Germany, maintenance only constitutes 6%, repairs 4% and accident repairs 8% (DAT-Veedol-Report, 2001). 

We discuss both the Proton Exchange Membrane as well as the Solid Oxide Fuel Cells in this chapter (PEMFC and SOFC). Both types are in full development, the PEMFC for mobile and stationary applications, and the SOFC for stationary applications as well as for auxiliary power generation for transport. 

Section IV emphasizes on nanoparticle catalysts for fuel cell applications. Fuel cell is a clean and desired future energy source. It is interesting to see that nanoparticle electrocatalysts play an important role in fuel cell development. Chapters 14 and 15 explore how nanoparticle catalysts can efficiently catalyze the reactions at anode and cathode of the fuel cells. 

In this chapter, we will pay attention to the basic or common materials requirements of the plate according to its functions in fuel cells. The emphasis will be put on plate materials used in transportation fuel cells because these applications, more directly for automotive, have potentially the largest market for fuel cells and the related material requirements are most challenging [1]. The various plate materials, fabrication process, and major challenges will be introduced and analyzed. The underlying mechanism and development trends will also be discussed. 

The competition between different plate materials or plates has become more severe in recent years this is beneficial for fuel cell design and allows manufacturing companies to make a better choice. The major competition is focused on polymer-based composite plates and metal plates. As qualitatively shown in Table 5.4, each material has its advantages and shortcomings. To this end, it is difficult and also too early to make a judgment on which of these two plate materials is better. In addition, as mentioned at the beginning of this chapter, with different market applications, the fuel cells. 

Apart from the promising electrochemical properties that will be exhaustively discussed through this chapter, carbon nanotubes have become a hot research topic due to their outstanding electronic, mechanical, thermal, optical and chemical properties and their biocompatibility. Near- and long-term innovative applications can be foreseen including nanoelectronic and nanoelectromechanical devices, held emitters, probes, sensors and actuators as well as novel materials for mechanical reinforcement, fuel cells, batteries, energy storage, (bio)chemical separation, purification and catalysis [20]. 

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