An anion exchange membrane (AEM) is a

semipermeable membrane Semipermeable membrane is a type of synthetic or biologic, polymeric membrane that allows certain molecules or ions to pass through it by osmosis. The rate of passage depends on the pressure, concentration, and temperature of the molecules o ...

generally made from

ionomer An ionomer () ('' iono-'' + '' -mer'') is a polymer composed of repeat units of both electrically neutral repeating units and ionized units covalently bonded to the polymer backbone as pendant group moieties. Usually no more than 15 mole perce ...

s and designed to conduct

anions An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

but reject gases such as

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

Applications

Anion exchange membranes are used in electrolytic cells and

fuel cells A fuel cell is an electrochemical cell that converts the chemical energy of a fuel (often hydrogen) and an oxidizing agent (often oxygen) into electricity through a pair of redox reactions. Fuel cells are different from most batteries in req ...

to separate reactants present around the two electrodes while transporting the anions essential for the cell operation. An important example is the hydroxide anion exchange membrane used to separate the electrodes of a

direct methanol fuel cell Direct methanol fuel cells or DMFCs are a subcategory of proton-exchange membrane fuel cells in which methanol is used as the fuel and a special proton-conducting polymer as the membrane (PEM). Their main advantage is low temperature operation an ...

(DMFC) or

direct-ethanol fuel cell Direct-ethanol fuel cells or DEFCs are a category of fuel cell in which ethanol is fed directly into the cell. They have been used as a model to investigate a range of fuel cell concepts including the use of PEM. Advantages DEFC uses Ethanol ...

(DEFC). Poly(fluorenyl-co-aryl piperidinium) (PFAP)-based anion exchange materials (electrolyte membrane and electrode binder) with high ion conductivity and durability under alkaline conditions has been demonstrated for use to extract hydrogen from water. Performance was 7.68 A/ cm² at 2 V, some 6x the performance of existing materials. Its yield is about 1.2 times that of commercial proton-exchange membrane technology (6 A/cm2), and it does not require the use of expensive

rare-earth element The rare-earth elements (REE), also called the rare-earth metals or rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), are a set o ...

s. The system works by increasing the specific surface area.

References

Fuel cells Electrochemistry Polymers Hydrogen technologies Membrane technology {{electrochem-stub

Applications

See also

References