Redox stability of metal-supported fuel cells with nickel/gadolinium-doped ceria anode

Metal-supported fuel cells (MSCs) are promising candidates for not only stationary but also mobile applications. Their appeal is in their potential to withstand reoxidation of the anode, which might occur by an interruption of the fuel supply or an emergency shutdown of the fuel cell system. A novel nickel/gadolinium-doped ceria anode (Ni/GDC) was recently introduced in a MSC concept of Plansee, almost doubling power density compared to cells with a nickel/yttria-doped zirconia (Ni/YSZ) anode. In this study, both cell concepts are compared concerning their ability to tolerate harsh redox cycles. Therefore, controlled redox cycles of the anodes were conducted at different temperatures. The response of the cell's power output to the redox cycling experiments was continuously recorded. In the case of MSCs with a Ni/YSZ anode, strong degradation occurs after redox cycling. In contrast, cells with a Ni/GDC anode exhibit significantly improved redox tolerance and cell performance improves with the number of redox cycles. For understanding this behavior, microstructural investigations of the Ni/GDC anode and the adjacent electrolyte were performed by FIB-SEM. The long-term redox behavior of MSCs with a Ni/GDC anode was also investigated by conducting more comprehensive redox cycles at 400 °C, 500 °C, and 600 °C.