The Primary Components of a Fuel Cell Are an Ion Materials for Fuel Cells

In the fuel cell, however, this simple chemical reaction is prevented by the electrolyte that separates the fuel (H2) from the oxidant (O2). The electrolyte serves as a barrier to gas diffusion, but permits ion transport. Accordingly, half cell reactions occur at the anode and cathode, producing ions that can traverse the electrolyte. For example, if the electrolyte conducts protons, H2 will be oxidized at the anode to form protons and electrons; the protons, after migrating across the electrolyte, will react at the cathode with O2 and electrons (Fig. 1): Anode: H2 → 2H+ + 2e(1) Cathode: 1⁄2 O2 + 2H+ + 2e→ H2O (2) Overall: 1⁄2 O2 + H2 → H2O (3) The flow of ionic charge through the electrolyte must be balanced by the flow of electronic charge through an outside circuit, and it is this balance that produces electrical power. Electrolytes in which protons, hydronium ions, hydroxide ions, oxide ions, and carbonate ions are mobile are all known, and are the basis for the many categories of fuel cells under development today. Desirable characteristics of fuel cell electrolytes are not only high ionic conductivity (which results in high efficiency), but also impermeability to gases, negligible electronic conductivity, chemical stability under a by Sossina M. Haile Materials for fuel cells