Fuel Cell Membranes

Polymer membrane

We are investigating new polymers for high temperature fuel cell membranes.  The polymer membrane is considered the “heart” of a polymer electrolyte membrane (PEM) fuel cell and represents a central challenge for the future of fuel cell devices.

Polybenzimidazoles imbibed with phosphoric acid are being prepared and tested in fuel cells at temperatures up to 200˚C. Our work over the last several years has been focused on a new process that allows high phosphoric acid levels, while still maintaining the mechanical strength for these highly loaded films.  The conductivities and fuel cell performance have increased substantially and now exhibit values suitable for commercial applications. 

The polymer membrane is considered the "heart" of a PEM fuel cell

We have also explored a great deal of new chemistry associated with the basic synthetic methods and new compositions to further improve the basic conductivity of the polymer membrane, as well as other properties.  The synthesis of new compositions continues with the belief that the polymer plays an important role in the conductivity. An extensive fuel cell test laboratory designed for high temperature membrane testing supports our work in this area.  We have also extended this work to investigate electrochemical hydrogen pumping for hydrogen separation and purification applications.

The video shows the hydrogen gas that is evolved from the cathode of an electrochemical hydrogen pump operating on a PBI membrane. The cell was a 10cm2 cell and the current displayed is the total cell current (divide by 10 to read A/cm2). At 0 amps, the cell does not evolve any hydrogen, showing that the membrane does not allow hydrogen to diffuse through the membrane. At the various applied currents, hydrogen on the anode side of the cell is being electrochemically pumped to the cathode as pure hydrogen gas (leaving any impurities in the anode exhaust). Imagine the amount of hydrogen produced from a commercial scale device which is capable of 3000-7000 times the hydrogen produced in the video!