The Identification of Degradation Parameters in SOC Under Load and OCV Aging Approaches

Recent SOC activities focus on upscaling systems to MW scale with target operation of several 10,000 h. These long lifetimes require new approaches for durability testing. In the present study, the influence of different operating parameters on degradation were studied by long-term cell testing in fuel cell and electrolysis mode (In-situ aging). Based on the results, accelerating parameters for degradation were identified and cells were treated/aged under these conditions without applying an external potential (OCV aging). This approach is cheaper and time saving as compared to conventional cell/stack long-term durability testing. Two commercial SOC cell designs, Fuel Electrode supported cells (FSC) and Electrolyte supported cells (ESC) were studied in this work. They were aged according to the two approaches (under operating conditions and with and without current load) and the obtained degradation effects compared to each other. Based on the cell composition and configuration the degradation parameters were observed to affect the cell performance to varying extents.