Five-layer MEA

FIGURE 27.34 Performance stability of a 3M five-layer MEA in single-ceU testing at Osaka Gas. (From 3M, www.3m.com.)... 

Five layer MEA consisting of the CCM with a Gas Diffusion Layer (GDL) on either side. 

Seven layer MEA combining the functions of the five-layer MEA and an inert Gasket or handling frame surrounding the active area. 

In a PEM fuel cell, a membrane having both anode and cathode sides coated with CLs is called an MEA. The MEA is the core of a PEM fuel cell, as it provides the location for the electrochemical reactions. A typical five-layer MEA includes the anode GDL, anode CL, membrane, cathode CL, and cathode GDL. As the reaction in a CL is three phased, an MEA should provide passages for the transport of electrons, protons, and reactant gases. Furthermore, it should also have the ability to remove product water. During the recent decades of fuel cell development, many MEA stmctures have been developed, and they will be discussed in detail in Chapter 2. 

Figure 12.1 is a schematic view of a typical PEM fuel cell. A membrane electrode assembly (MEA) usually refers to a five-layer structure that includes an anode gas diffusion layer (GDL), an anode electrode layer, a membrane electrolyte, a cathode electrode layer, and a cathode GDL. Most recently, several MEA manufacturers started to include a set of membrane subgaskets as a part of their MEA packages. This is often referred to as a seven-layer MEA. In addition to acting as a gas and... 

Membrane electrode assemblies (MEAs) are typically five-layer structures, as shown in Figure 10.1. The membrane is located in the center of the assembly and is sandwiched by two catalyst layers. The membrane thickness can be from 25 to 50 pm and, as mentioned in Chapter 10, made of perfluorosulfonic acid (Figure 11.3). The catalyst-coated membranes are platinum on a carbon matrix that is approximately 0.4 mg of platinum per square centimeter the catalyst layer can be as thick as 25 pm [12], The carbon/graphite gas diffusion layers are around 300 pm. Opportunities exist for chemists to improve the design of the gas diffusion layer (GDF) as well as the membrane materials. The gas diffusion layer s ability to control its hydrophobic and hydrophilic characteristics is controlled by chemically treating the material. Typically, these GDFs are made by paper processing techniques [12],... 

In a PEMFC, the combination of anode/membrane/cathode is referred to as a membrane eleetrode assembly (MEA). Normally, the MEA is a five-layer eomposite strueture that ineludes anode GDL, anode CL, membrane, cathode GDL,... 

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