Durability of fuel cell components for μCHP application

Kurzfassung

Buildings energy necessities are not only reduced to electricity but also to heat. Fuel Cells (FC) can cover this double demand with Combined Heat and Power (CHP) systems at high efficiency becoming in a key technology for decarbonization a large amount of end users and scenarios. The most typical application in Europe is micro-CHP (0.5-5 kWe) using PEMFC [1]. The KPI 2030 target for durability of FC stacks in this application limits degradation rated power at constant current to 0.2% / 1000 h (for BoL cell voltage of 700 mV, the maximum degradation is then 1.4 µV h-1). Additionally, the minimum testing time for demonstration is 3000 hr which creates an additional difficulty for demonstration. To address this goal, identification of the dominant degradation mechanisms of the stack components in real application is unavoidable followed by a categorization of the observed mechanisms into component-based for mechanisms inherent to the material (i.e dissolution or detachment of particles) or operation-based for mechanisms provoked by the operation (i.e. open circuit). In this work, an extensive study of the degradation of PEMFC stack components used for mCHP application has been carried out. A broad analysis of data from a real application stack as well as ex-situ analysis of aged bipolar plates and MEAs has been carried out to identify the main degradation mechanisms isolated from Balance of Plant (BoP). Furthermore, short stacks were tested in laboratory under a specific application-related load cycle. Additionally, single cell test of the MEAs were also performed to isolate the intrinsic degradation of the MEAs from any degradation induced from BoP or additional Stack component. Short stack components and single-cell MEAs have been also analyzed with ex-situ methods such as SEM-EDX and compared to the real application samples. Some component materials have been identified as possible sources of contamination of MEAs as well as some operation procedures has been also recognized as a possible source of improvement with the inclusion of system-compatible recovery procedures