Fuel Cells: Membranes
Fuel Cell Electrolytes
Membrane Fuel Cells
“A fuel cell is a device that converts the chemical energy from a fuel into electricity through a chemical reaction with oxygen or another oxidizing agent. Hydrogen is the most common fuel, but hydrocarbons such as natural gas and alcohols like methanol are sometimes used. Fuel cells are different from batteries in that they require a constant source of fuel and oxygen to run, but they can produce electricity continually for as long as these inputs are supplied.
Welsh Physicist William Grove developed the first crude fuel cells in 1839. The first commercial use of fuel cells was in NASA space programs to generate power for probes, satellites and space capsules. Since then, fuel cells have been used in many other applications. Fuel cells are used for primary and backup power for commercial, industrial and residential buildings and in remote or inaccessible areas. They are used to power fuel cell vehicles, including automobiles, buses, forklifts, airplanes, boats, motorcycles and submarines.
There are many types of fuel cells, but they all consist of an anode (negative side), a cathode (positive side) and an electrolyte that allows charges to move between the two sides of the fuel cell. Electrons are drawn from the anode to the cathode through an external circuit, producing direct current electricity. As the main difference among fuel cell types is the electrolyte, fuel cells are classified by the type of electrolyte they use. Fuel cells come in a variety of sizes. Individual fuel cells produce very small amounts of electricity, about 0.7 volts, so cells are "stacked", or placed in series or parallel circuits, to increase the voltage and current output to meet an application’s power generation requirements. In addition to electricity, fuel cells produce water, heat and, depending on the fuel source, very small amounts of nitrogen dioxide and other emissions. The energy efficiency of a fuel cell is generally between 40-60%, or up to 85% efficient if waste heat is captured for use.”
(Wikipedia, Fuel Cells, 7/9/2012)
“Fuel cells may be classified according to the kind of electrolyte used. For example, fuel cells may be classified as polymer electrolyte membrane fuel cells (PEMFCs), phosphoric acid fuel cells, molten carbonate electrolyte fuel cells, and solid oxide fuel cells.
A PEMFC includes an anode, a cathode, and a polymer electrolyte membrane disposed therebetween. The anode includes a catalyst layer that promotes oxidation of a fuel, and the cathode includes a catalyst layer that promotes reduction of an oxidizer.
The polymer electrolyte membrane of the PEMFC functions not only as an ion conductor for the movement of protons from the anode towards the cathode, but also as a separation layer preventing mechanical contact between the anode and the cathode. Thus, it is desirable for the polymer electrolyte membrane to have excellent ion conductance, electrochemical stability, high mechanical strength, high heat resistance, and film formation properties.”
[Choi, US Patent 8,211,588 (7/3/2012)]
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Roger D. Corneliussen
Maro Polymer Links
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Copyright 2012 by Roger D. Corneliussen.
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* Date of latest addition; date of first entry is 7/10/2012.