PBI TM2 Membrane with Phosphoric Acid:

PBI TM2 membranes are PBI membranes doped with phosphoric acid for high temperature PEM fuel cell or H2 pump applications. Typical application temperature is around 160-180°C depending on the catalyst, electrode, cell and performance requirements.

The TM2 membrane is 3-4 mil thick and is available in many sizes. For the convenience of different users, the standard sizes are nominally: 10x10cm, 10x20cm, 20x20cm, 20x30cm, and 30x30cm. Each membrane is packaged individually in a resealable bag with a stiff polyester support layer and polyethylene protective layers on top and bottom. 

The weight of phosphoric acid in TM2 membranes, if calculated at 85% concentration, is about 4 times (3.5-4.5) the PBI weight. Since the membrane is already doped with acid, it can be used by removing the packaging and positioning it between suitable electrodes. If desired, a small amount of phosphoric acid can be brushed on the catalyst layer of the electrodes before compressing the MEA together to improve the interface. Because TM2 membranes contain phosphoric acid, consult the SDS for appropriate PPE.

The polymers in TM2 membrane are meta-Polybenzimidazole as shown below.