Hydrogen polymer electrolyte membrane (PEM) fuel cell systems enable long range and short refuelling times. The commercial success, however, requires high durability of the fuel cells. Thus, more than 5,000 operating hours with a max. acceptable loss of 10% cell voltage were defined as lifetime target in international development programs.
Currently available vehicles on the market, however, often show higher power losses, since the use of PEM fuel cells in automotive applications significantly increases the requirements for the materials and operating/control strategies of the fuel cell system. Strongly alternating load profiles require a high-dynamic load-bearing capacity of the cells, the local air quality can influence the cathode catalyst and the fuel cell is – if not operated – exposed to the ambient temperatures. In particular, freezing conditions – i.e. temperatures well below 0°C – have proved to be problematic. The chemical reaction produces water on the cathode side, which in turn can lead to damage during freezing. The highly dynamic load profiles of a vehicle also lead to severe fluctuations in the state variables, e.g. reactant availability and membrane humidity, which are decisive for the efficiency and the lifetime of the fuel cell. In order to enable the attainment of the intended life-time targets, new materials, but also optimized operating strategies of the PEM system have to be developed.
The present project focuses on overcoming the above mentioned hurdles and has the following defined goals: Low-damage processes for start-up and shutdown (especially during freezing conditions), new control procedures for high-dynamic PEM fuel cell operation with implicit consideration of life expectancy and/or prolongation thereof, automotive Fuel Cell Control Unit (FCCU) for above mentioned operating and control strategies as well as for cell recovery strategies. The developed solutions are to be validated at stack and system level on corresponding test beds. The project is scientifically challenging as it aims to generate new solutions in areas that have been little explored so far, and in doing so, the cooperation of scientists from different disciplines are required. The targeted validation at system level offers high potential for future commercial implementations. Thus, the project results will provide a significant contribution to sustainable mobility through PEM fuel cell technology.