All Topics  
Membrane electrode assembly

 

 
   Email Print
   Bookmark   Link
 

 

Membrane electrode assembly
 
 
  Topics Membrane electrode assembly Topic Home

A membrane electrode assembly (MEA) is an assembled stack of proton exchange membrane
Proton exchange membrane

A proton exchange membrane or polymer electrolyte membrane is a semipermeable membrane generally made from ionomers and designed to proton conductor while being impermeable to gases such as oxygen or hydrogen....
s (PEMs), catalyst and electrode used in a fuel cell
Fuel cell

A fuel cell is an Electrochemistry conversion device. It produces electricity from fuel and an Oxidizing agent , which react in the presence of an electrolyte....
. The PEM is sandwiched between two electrodes which have the catalyst embedded in them. The electrodes are electrically insulated from each other by the PEM. These two electrodes make up the anode and cathode
Electrode

An electrode is an electrical conductor used to make contact with a nonmetallic part of a Electronic circuit . The word was coined by the scientist Michael Faraday from the Greek language words elektron and hodos, a way....
 respectively.

The PEM is a proton permeable but electrical insulator
Electrical insulation

An insulator, also called a dielectric, is a material that resists the flow of electric current. An insulating material has atoms with tightly bonded valence electrons....
 barrier. This barrier allows the transport of the protons from the anode to the cathode through the membrane but forces the electrons to travel around a conductive path to the cathode.






Discussion
Ask a question about 'Membrane electrode assembly'
Start a new discussion about 'Membrane electrode assembly'
Answer questions from other users
Full Discussion Forum



Encyclopedia


A membrane electrode assembly (MEA) is an assembled stack of proton exchange membrane
Proton exchange membrane

A proton exchange membrane or polymer electrolyte membrane is a semipermeable membrane generally made from ionomers and designed to proton conductor while being impermeable to gases such as oxygen or hydrogen....
s (PEMs), catalyst and electrode used in a fuel cell
Fuel cell

A fuel cell is an Electrochemistry conversion device. It produces electricity from fuel and an Oxidizing agent , which react in the presence of an electrolyte....
. The PEM is sandwiched between two electrodes which have the catalyst embedded in them. The electrodes are electrically insulated from each other by the PEM. These two electrodes make up the anode and cathode
Electrode

An electrode is an electrical conductor used to make contact with a nonmetallic part of a Electronic circuit . The word was coined by the scientist Michael Faraday from the Greek language words elektron and hodos, a way....
 respectively.

The PEM is a proton permeable but electrical insulator
Electrical insulation

An insulator, also called a dielectric, is a material that resists the flow of electric current. An insulating material has atoms with tightly bonded valence electrons....
 barrier. This barrier allows the transport of the protons from the anode to the cathode through the membrane but forces the electrons to travel around a conductive path to the cathode. Companies such as DuPont
DuPont

E. I. du Pont de Nemours and Company is an United States chemical industry that was founded in July 1802 as a gunpowder mill by Eleuth?re Ir?n?e du Pont....
, Dow and E-TEK produce PEM. DuPont PEM are offered under the trade name
Trade name

A trade name, also known as a trading name or a business name, is the name which a business trades under for commercial purposes, although its registered, Legal name , used for contracts and other formal situations, may be another....
 Nafion
Nafion

Nafion is a sulfonated tetrafluoroethylene based fluoropolymer-copolymer discovered in the late 1960s by Walther Grot of DuPont. It is the first of a class of synthetic polymers with ionic properties which are called ionomers....
. The commonly used Nafion PEM are Nafion 112, 115, 117, 105.

The electrodes are heat pressed onto the PEM. Commonly used materials for these electrodes are carbon cloth or Toray carbon fiber paper . E-TEK produce a carbon cloth called ELAT which maximizes gas transport to the PEM as well as moves water vapor
Water vapor

Water vapor or water vapour , also aqueous vapor, is the gas phase of water . Water vapor is one Phase of the water cycle within the hydrosphere....
 away from the PEM. Imbedding ELAT with Noble metal
Noble metal

Noble metals are metals that are resistant to corrosion or oxidation, unlike most base metals. They tend to be precious metals, often due to rarity in the crust of the Earth....
 catalyst allows this carbon cloth to also act as the electrode.

Complete MEAs are made be several companies, including PEMEAS (now a division of BASF Fuel Cell). Many of these companies specialize in high volume products. There are some companies which produce custom or low quantity MEAs, such as Lynntech, Inc.

Platinum is one of the most commonly used catalysts, however other platinum group
Platinum group

The platinum group metals sometimes collectively refers to six metallic chemical element clustered together in the periodic table.These elements are all transition metals, lying in the d-block ....
 metals are also used. Ruthenium and platinum are often used together, if CO is a product of the electro chemical reaction
Chemical reaction

A chemical reaction is a process that always results in the interconversion of chemical substances. The substance or substances initially involved in a chemical reaction are called reactants....
 as CO poisons the PEM and impacts the efficiency of the fuel cell. Due to the high cost of these and other similar materials, research is being undertaken to develop catalysts that use lower cost materials as the high costs are still a hindering factor in the wide spread economical acceptance of fuel cell technology.

Current service life
Service life

A product's service life is its expected lifetime, or the acceptable period of use in service. It is the time that any manufactured item can be expected to be 'serviceable' or supported by its originating manufacturer....
 is 7,300 hours under cycling conditions, while at the same time reducing platinum group metal loading to 0.2 mg/cm2.

See also

  • Electroosmotic pump
    Electroosmotic pump

    An electroosmotic pump , or EO pump, is used for removing liquid flooding water from channels and gas diffusion layers and direct hydration of the proton exchange membrane in the membrane electrode assembly of the proton exchange membrane fuel cells....


External links