An Overview of Fuel Cells
A fuel cell is an electrochemical cell that converts the chemical energy of fuel (usually hydrogen) and an oxidizing agent (typically oxygen) into electricity via a pair of redox reactions. Fuel cells differ from other batteries in that they require a constant source of fuel and oxygen to sustain their chemical reaction, whereas batteries get chemical energy from metals and their ions and oxides. Fuel cells produce energy for as long as fuel and oxygen are present.
There are many types of fuel cells, though all consist of three common features: an anode, cathode, and electrolyte. Additionally, all fuel cells have the same general purpose. The anode, cathode, and electrolyte allow ions such as positively charged hydrogen ions called protons to move between the two sides of the Cover fuel cell. At the anode, a catalyst causes the fuel to undergo an oxidation reaction that generates ions and electrons. The ions then move from the anode to the cathode via the electrolyte. Simultaneously, electrons are flowing from the anode to the cathode through an external circuit, resulting in the creation of direct current electricity. At the cathode, a second catalyst causes ions, electrons, and oxygen to react, forming condensation and other byproducts.
Fuel cells are classified by the type of electrolyte they use and by the variations in their startup time. There are four main types of fuel cells: proton-exchange membrane fuel cells (PEMFCs), Phosphoric acid fuel cells (PAFCs), Solid acid fuel cells (SAFCs), Orifice Fuel Cell and Alkaline fuel cells (AFCs). PEMFCs, also known as polymer electrolyte membrane fuel cells, are a type of fuel cell primarily used for transport applications, as well as stationary fuel-cell applications and portable fuel-cell applications. Their distinguishing features include lower temperature and pressure ranges as well as a proton-conducting polymer electrolyte membrane. PEMFCs are the leading replacement for alkaline fuel cells, an aging technology.
PAFCs are a type of fuel cell that uses liquid phosphoric acid as an electrolyte. PAFC fuel cells were the first to be commercialized after their development and testing in the 1960s and 70s. Since their introduction, PAFCs have improved significantly in stability, performance, and cost. These fuel cells are popular in early stationary applications. Operating range of PAFCs is from approximately 150 to 210 degrees celsius. Solid acid fuel cells are unique in the use of a solid acid material as the electrolyte. At low temperatures, solid acids have a molecular structure similar to that of most salts. At warmer temperatures (140-150 celsius), some solid acids undergo a phase transition and become superprotonic structures, increasing their conductivity by a significant amount. Current SAFC systems can have liftimes in the thousands of hours.
The final type of fuel cell, the alkaline fuel cell, was developed and introduced in 1959. Alkaline fuel cells were the primary source of electrical energy used in the Apollo space program. This fuel cell consists of two porous cabron electronics with a suitable catalyst. In alkaline fuel cells, the reaction involves the combination of hydrogen and oxygen gas to form water. The Outlet Fuel Cell runs continuously until its supply of this mixture is exhausted. AFCs can operate at extreme temperatures between 343 and 413 Kelvin.
- charles price
- Posted on June 19, 2020 electronics
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