Direct Energy, 2018a

230 9.6 Fuel Cells
Fuel cell components
Anode
Cathode
Electrolyte
Membrane
Catalyst
Fuel
Oxidizer
Fuel cell system components
Fuel processor
Flow plates
Heat recovery system
Inverter
Other electronics
Table 9.3: Fuel cell components.
In addition to these components, fuel cells often contain a thin polymer
membrane, and fuel cell electrodes are often coated with a catalyst which
speeds up the chemical reaction. An example material used to make the
membrane is a 0.076 cm layer of polystyrene [60, ch. 10]. Another example
membrane is polybenzimidazole containing phosphoric acid [128, ch. 37].
Membranes allow ions, but not the fuel and oxidizer to pass through [60,
ch. 10]. In addition to selectively allowing ions to pass through, membranes
should be chemically stable to not break down in the presence of the often
acidic or alkaline electrolyte, should be electrical insulators, and should be
mechanically stable [60, ch. 10]. A useful catalyst speeds up the reaction at
the electrodes. In addition, a good catalyst must not dissolve or oxidize in
the presence of the electrolyte, fuel, and oxidizer [60, ch. 8]. Additionally,
it should only catalyze the desired reaction, not other reactions [60, ch.
8]. Examples of catalysts used include platinum, nickel, acetylacetone, and
sodium tungsten bronze Na x WO 3 with 0.2