PEFC Stack for Operating Temperatures up to 130 °C

Kurzfassung

At the DLR Institute of Technical Thermodynamics new concepts for fuel cell stacks are being developed for various applications and load profiles. Thereby, the main focus lies on the simplification of the stacks for reaching a cost reduction as well as an increase of the power density. Today’s polymer electrolyte fuel cells (PEFCs) are applicable only within a limited range of the operating temperature. This limitation restricts the spectrum of possible applications and hinders their flexibility during operation. Therefore, the continuous operation at elevated temperatures or in an extended temperature range for a limited time offers the opportunity to overcome these restrictions. Unfortunately, higher operating temperatures lead to new challenges, especially when conventional materials for the membrane electrode assemblies (MEAs) are used: In order to avoid critical operating conditions and to ascertain a sufficient durability and performance of a fuel cell stack, special concepts regarding the bipolar plates, the cooling strategy, the MEAs themselves as well as a closer look on the water management are essential. Furthermore, the operating strategy of the stack has to be adapted with respect to all of the stack components.