Hydrogen technologies

Membranes for the hydrogen economy

Membranes are expected to play an important role at many points in the production and use of green hydrogen. This starts with the provision of clean water for electrolysis (Water purification), to the electrochemical splitting of water in polymer electrolyte membrane (PEM) electrolyzers, to the reconversion to electricity using PEM fuel cells.

Membrane humidifiers, which we are developing at the IGB and testing in automated test rigs (Moisture management), can also be used for water management in fuel cells.

Other possible applications for membranes are the separation of H2-containing gas mixtures by means of membranes, such as palladium membranes (Gas separation) or the production of hydrogen in so-called membrane reactors by direct splitting of water (Oxygen conducting perovskite capillary membranes).

Polymer electrolyte membranes for electrolysis and fuel cells

The polymer electrolyte membranes (PEM) used in electrolyzers and fuel cells consist of ionomer materials in which acidic or basic functionalities determine the ion transport through the material. Our specialty is the introduction of an additional inorganic phase into the ionomer to increase chemical, mechanical and thermal stability and to improve the barrier function for other substances.

We have set up various test rigs to investigate the cross-over of ionomer membranes, e.g. of gases such as hydrogen or even ethanol, in a wide process window.

Optimization of the interface between ionomer membrane and electrodes

For alcohol fuel cells, among other applications, we have developed an aqueous binder system based on sPEEK (sulfonated poly[ether ether ketone]) to optimize the compatibility of these layers and apply the layers using screen printing technology. The requirements for these layers range from suitable porosity for reactant delivery and removal to high electrical conductivity.

Composite membrane.
© Fraunhofer IGB
SEM image of a mixed matrix ionomer membrane
Test cell for determining hydrogen crossover
© Fraunhofer IGB
Test cell for determining hydrogen crossover at pressures up to 50 bar and temperatures up to 80°C
Determination of ethanol permeability in an fl-fl diffusion cell. Shown is the ethanol permeability of composite membranes of different compositions compared to the pure polymer membrane.
© Fraunhofer IGB
Determination of ethanol permeability in an fl-fl diffusion cell. Shown is the ethanol permeability of composite membranes of different compositions compared to the pure polymer membrane.
Arrhenius plot of different gases for cross-over across an ionomer membrane
© Fraunhofer IGB
Arrhenius plot of different gases for cross-over across an ionomer membrane

Services

  • Development of mixed-matrix PEM membranes for increased stability and improved barrier function
  • Investigation of cross-over in purpose-built test rigs
  • Optimization of the interfaces between ionomer membrane and electrodes

Publications

  1. Roelofs, K. S., Hirth, T., & Schiestel, T. (2010). Sulfonated poly(ether ether ketone)-based silica nanocomposite membranes for direct ethanol fuel cells. Journal of Membrane Science, 346(1), 215-226. doi:https://doi.org/10.1016/j.memsci.2009.09.041
  2. Roelofs, K. S., Hirth, T., & Schiestel, T. (2011). Dihydrogenimidazole modified silica-sulfonated poly(ether ether ketone) hybrid materials as electrolyte membranes for direct ethanol fuel cells. Materials Science and Engineering: B, 176(9), 727-735. doi:https://doi.org/10.1016/j.mseb.2011.02.029.
  3. C. Cremers, F. Jung, B. Kintzel, K.S. Roelofs, T. Schiestel, J. Tübke, Development of Direct Ethanol Fuel Cell Membrane Electrode Assemblies Using Sulfonated Polyetheretherketone Mixed-Matrix Membranes, ECS Trans., 25 (1), 2009, 1685.