20 cm, x 28 cm sheets of Sustainion® Alkaline Anion Exchange Membrane with PTFE support for easier handleability and greater strength. It is moderately basic and designed for use with supporting electrolyte. Dioxide Materials has optimized it for use in anion exchange membrane water electrolyzers electrolyzers as described in Masel et al. ECS Transactions, 75 (14) 1143-1146 (2016).
See also patents 9,370,773, 9,481,939.
The anion membranes are supplied in dry-chloride form. They consequently have to be converted to the hydroxide form by exposing them to a strong base. Dioxide Materials recommends soaking the membrane in a large bath of 1M KOH for 24 - 48 hours in order to convert the membrane chloride form into the hydroxide form. This activation also helps in strengthening the membrane via crosslinking with KOH as identified by a recent NMR study . Furthermore, during this process the membrane swells.
Note: The membrane is a sandwich structure with a thin porous PTFE layer coated with sustainion 37 on both sides. The PTFE decreases the transport of water in the membrane so they are less efficient in CO2 electrolyzers.