TABLE OF CONTENTS David Linden and Thomas B. Reddy
A fuel cell is a galvanic device that continuously converts the chemical energy of a fuel (and oxidant) to electrical energy. Like batteries, fuel cells convert this energy electrochemically and are not subject to the Carnot cycle limitation of thermal engines, thus offering the potential for highly efficient conversion. The essential difference between a fuel cell and a battery is the manner for supplying the source of energy. In a fuel cell, the fuel and the oxidant are supplied continuously from an external source when power is desired. The fuel cell can produce electrical energy as long as the active materials are fed to the electrodes. In a battery, the fuel and oxidant (except for metal/air batteries) are an integral part of the device. The battery will cease to produce electrical energy when the limiting reactant is consumed. The battery must then be replaced or recharged.
The electrode materials of the fuel cell are inert in that they are not consumed during the cell reaction, but have catalytic properties which enhance the electroreduction or electrooxidation of the reactants (the active materials).
The anode active materials used in fuel cells are generally gaseous or liquids fuels (compared with the metal anodes generally used in most batteries), such as hydrogen, methanol, hydrocarbons, natural gas, which are fed into the anode side of the fuel cell. As these materials are...
