Category: 09. Fuel-Cell Fundamentals

A second major type of fuel cell is the SOFC. Here the electrolyte is a ceramic material that conducts oxygen ions. The electrode reactions for a SOFC were provided in Table 9.2. Note that in contrast to the PEMFC, although the overall reaction is the same, water is produced at the anode rather than the cathode. Additionally,…

The electrolyte in PEM fuel cells is a solid polymer material with covalently bonded sulfonic acid groups. These materials are similar to ion-exchange resins. A cation is associated with each negatively charged sulfonic acid group. For fuel-cell applications, the cations are protons. In other applications, see Chapter 14 and the chlor-alkali process, sodium ions are present rather…

Electrode structures were introduced in Chapter 5. One of the distinguishing features of a fuel-cell electrode is that three phases are present. First, there is a solid phase that is electronically conductive to supply or remove electrons. Second, an electrolyte phase that conducts ions is needed. The electrolyte may be solid or liquid. So far, this…

A key objective in this chapter is to gain a detailed understanding of what is known as the polarization curve. This curve represents the steady-state relationship between the potential of the cell, Vcell, and its current density, i. It is typically measured experimentally. During this measurement, the temperature and pressure are held constant, and the flow of reactants…

There are many different kinds of fuel cells, which are distinguished primarily by the electrolyte used and also by the type of fuel that is consumed. The most common fuel is hydrogen gas; hydrocarbons are frequently reformed to produce hydrogen for consumption in the fuel cell. Fuels other than hydrogen can also be used directly,…

Operation of a methanol fuel cell is illustrated in Figure 9.1. This particular fuel cell uses a proton-exchange membrane separator in which the ionic current is carried by protons. In contrast to batteries, where we were careful to use the terms negative and positive for electrodes rather than anode and cathode, the terms anode and cathode…