Solid Oxide Fuel Cell Operating Principle

Figure 8-2 Solid Oxide Fuel Cell Operating Principle (2)...

Mukherjee, J., Linic, S. First-principles investigations of electrochemical oxidation of hydrogen at solid oxide fuel cell operating conditions. J. Electrochem. Soc. 2007,154, B919-24. 

Solid oxide fuel cell technology Principles, perfonnance and operations... 

Ingram DB, Linic S (2009) First-principles analysis of the activity of transition and noble metals in the direct utilization of hydrocarbon fuels at solid oxide fuel cell operating conditions. J Electrochem Soc 156(12) B1457-B1465... 

Huang K, Goodenough JB (2009) Solid oxide fuel cell technology principles, performance and operations, Woodhead Energy Series. Woodhead Publishing Ltd, Cambridge, p 344... 

K. Huang, J.B. Goodenough, Solid Oxide Fuel Cell Technology Principles, Performance and Operations (Woodhead Publishing Ltd., UK, 2009)... 

Figure 3.-/. Operating principle of a solid oxide fuel cell (a) and of a chemical cogenerator (b).41 Reprinted with permission from the American Chemical Society.

Figure 25 Schematic diagram showing the operating principles of a SOFC running on natural gas (R. Mark Ormerod Solid oxide fuel cells Chemical Society Reviews 32 17-28 (2003). Reprinted with permission of The Royal Society of Chemistry)...

In Section 21.3, the fundamental problems arising in the development of planar solid oxide fuel cells have been listed sealing, corrosion of the bipolar plates, and the development of mechanical stresses in the numerous ceramic components found in such fuel cells. Solutions depend not only on the selection of suitable materials for the individual component parts of the fuel cells, but also on respecting certain principles of design and operation. 

Fig. 1 Operating principle of a solid oxide fuel cell...

Solid oxide fuel cells (SOFQ are promising electrochemical energy conversion systems to produce power for portable, mobile, and stationary apphcations ranging from several W to MW. The advantage that SOFCs have over other fuel cell systems is their direct operation on hydrocarbons and air (without being restricted to a hydrogen distribution net). Operation principle, temperature regime, and materials were introduced and are detailed in further articles. 

Fig. 3.1 Solid Oxide Fuel Cell (SOFC) operating principle...

A fuel cell is a device capable of converting chemical energy bound in a fuel to electrical energy. A large number of reviews of solid oxide fuel cells (SOFCs) can be found in the literature.The operating principle of an SOFC is illustrated in Fig. 12.15. A solid electrolyte, capable of conducting oxide ions, is sandwiched between two porous electrodes (the cathode and anode). An oxidant (typically the Og in air) is reduced at the cathode and fuel (e.g. Hg, CO, or NHg) is oxidized at the anode. More specifically, oxygen is dissociated and converted to oxide ions at the cathode/electrolyte interface, whereas the electrochemical oxidation of the fuel takes place... 

The materials that have been studied the most are yttria stabilized zirconia, doped ceria with gadolinium and lanthanum gallate doped with strontium and magnesium. The solid oxide fuel cells can, in principle, operate in a wide temperature range between 500 °C and... 

The carbonate fuel cell principle of operation is based on transfer of the oxygen in the form of carbonate ions from the cathode to the anode. In many ways, this is similar to Solid Oxide Fuel Cell (SOFC) technology, with the main differences being that the medium of the ionic transfer is a molten carbonate immobilized in a ceramic matrix. Various eutectic mixtures of lithium, potassium, and sodium carbonates have been used as electrolyte with the most prevalent ones being 38Li/62K or 60Li/40Na carbonate mixtures. 

Fuel cells can be classified into phosphoric acid fuel cells, molten carbonate fuel cells, solid oxide full cells, polymer electrolyte membrane fuel cells, and alkaline full cells according to the type of electrolyte used (150). All these fuel cells operate on the same principle, but the t) e of fuel used, operating speed, the catalyst used and the electrolyte used are different. In particular, pol5mier electrolyte membrane fuel cells can be used in small-sized stationary power generation equipment or transportation systems due to their high reaction speed, low operating temperature, high output density, rapid startup, and variation in the requested output. 

The operating principle of a SOFC is schematically shown in Fig. 11.25. When an external load is applied to the cell, oxygen is reduced at the porous air electrode to produce oxide ions. These ions migrate through the solid electrolyte to the fuel electrode, and oxide ions react with the fuel, or CO, to produce HjO or COj. 

DMFCs and direct ethanol fuel cells (DEFCs) are based on the proton exchange membrane fuel cell (PEM FC), where hydrogen is replaced by the alcohol, so that both the principles of the PEMFC and the direct alcohol fuel cell (DAFC), in which the alcohol reacts directly at the fuel cell anode without any reforming process, will be discussed in this chapter. Then, because of the low operating temperatures of these fuel cells working in an acidic environment (due to the protonic membrane), the activation of the alcohol oxidation by convenient catalysts (usually containing platinum) is still a severe problem, which will be discussed in the context of electrocatalysis. One way to overcome this problem is to use an alkaline membrane (conducting, e.g., by the hydroxyl anion, OH ), in which medium the kinetics of the electrochemical reactions involved are faster than in an acidic medium, and then to develop the solid alkaline membrane fuel cell (SAMFC). 

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