Selected hydrogen production activities at the Institute of Technical Thermodynamics of DLR focused on the electrodes and stack design

Kurzfassung

The Institute of Technical Thermodynamics started developing various kinds of electrolysers for a large range of applications approx. in 1985. The main topics are the development of stabilized electrodes for applications with drastically load changes and high durability as well as and the understanding of mechanisms and degradation effects. This poster will focused onf the recentlast main topics. First we will show the development of unitized regenerative fuel cells (URFC) at DLR. The effects of different configurations and compositions of platinum and iridium oxide electrodes for the oxygen reaction of URFC are described. Bifunctional oxygen electrodes are important for URFC development because favorable properties for the fuel cell and the electrolysis modes must be combined into a single electrode. The bifunctional electrodes were studied under different combinations of catalyst mixtures, multilayer arrangements and segmented configurations with single catalyst areas. The second topic to be presented is the description of an EU fundeding project coordinated by DLR: The project RESelyser develops high pressure, highly efficient, low cost alkaline water electrolysers that can be integrated with renewable energy power sources (RES) using an advanced membrane concept, highly efficient electrodes and a new cell design. A new separator membrane with internal electrolyte circulation and an adapted design of the cell to improve mass transfer, especially gas evacuation is investigated and demonstrated. Intermittent and varying load operation with RES will be addressed by improved electrode stability and a cell concept for increasing the gas purity of hydrogen and oxygen especially at low power operation. Also the system architecture will be optimized for intermittent operation of the electrolyser. First results will be presented: high performance electrodes with a plasma sprayed coating layer have a surface of more than 30 000 cm2/cm2 electrode area and show high performance and stability. A double layer diaphragm with internal KOH supply improves the gas purity and high current density performance of the cell. The RESelyser Project is supported by the European Union's Seventh Framework Programme (FP7/2007-2013) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement n° [278732]