Anode materials Future directions

One of the main objective of SOFCs in the future is the use of gaseous mixtures of C0-H2-H20 produced by coal gasification plants or by steam reforming a hydrocarbon fuel, especially methane. Very little data is available about the direct oxidation of methane in SOFCs [96, 97], Steele et al. [97] have recently confirmed the poor electrocatalytic activity of Pt electrodes for the anodic oxidation of methane at 800 °C. Although nickel fulfills major requirements for anode materials when H2 and CO are employed as fuels, its use for the direct oxidation of methane encourages carbon deposition. To overcome this problem, alternative anode materials must be... 

Chapter 1 of this book discusses several main cell components cathodes, anodes, electrolyte solutions, and separators. Typically, the commonly used syntheses methods of these materials are discussed, along with their principal properties and the requirements for successful implementation in high-end cells. The chapter concludes with the forecast of future directions in cell materials development. 

Alternative Anode Materials-Oxide Anode and Hydrocarbon Fuels Future Directions... 

Another important parameter that has to be taken into account when choosing the appropriate diffusion layer is the overall cost of the material. In the last few years, a number of cost analysis studies have been performed in order to determine fuel cell system costs now and in the future, depending on the power output, size of the system, and number of xmits. Carlson et al. [1] reported that in 2005 the manufacturing costs of diffusion layers (for both anode and cathode sides) corresponded to 5% of the total cost for an 80 kW direct hydrogen fuel cell stack (assuming 500,000 units) used in the automotive sector. The total value for the DLs was US 18.40 m-, which included two carbon cloths (E-TEK GDL LT 1200-W) with 27 wt% P ILE, an MPL with PTFE, and Cabot carbon black. Capital, manufacturing, tooling, and labor costs were included in the total. 

Direct methanol fuel cells (DMFCs) are attracting much more attention for their potential as clean and mobile power sources for the near future [1-8], Generally, platinum (Pt)- or platinum-alloy-hased nanocluster-impregnated carbon supports are the best electrocatalysts for anodic and cathodic fuel cell reactions. These materials are veiy expensive, and thus there is a need to minimize catalyst loading without sacrificing electro-catalytic activity. Because the catalytic reaction is performed by fuel gas or fuel solution, one way to maximize catalyst utilization is to enhance the external Pt surface area per unit mass of Pt. The most efficient way to achieve this goal is to reduce the size of the Pt clusters. 

As discussed in this entry, a number of novel materials and composites have been proposed as potential anodes for direct hydrocarbon solid oxide fuel cells. While many are promising, a commercially viable solution has not yet been found. The discusskm in this entry is deliberately framed arotmd the cxmcepts of ionic and electronic conductivity, electrocatalysis, and stability. It is essential for future researchers to address all of these topics when discussing new materials. The schematic in Fig. 3.4 represents both the complexity of the problem and the simpUcity that could potentially be achieved if a material meeting all of these requirements can be found. 

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