Effect of infiltration on performance of Ni-YSZ fuel electrodes

Ni-YSZ electrodes for solid oxide cells (SOCs) can have a diverse range of compositions, porosities, and particle sizes - factors that impact electrochemical performance. A typical Ni-YSZ structure in an anode-supported cell fired at 1400^oC has feature sizes of ~ 0.5 µm that yield desirably low polarization resistance values < 0.1 Ω cm² at 800^oC in H2-H2O fuel, along with good stability. Decreasing feature size increases three-phase boundary density, thereby reducing polarization resistance and improving low-temperature cell performance. However, the feature size that can be reached in anode-supported cells is limited by the relatively high co-firing temperature. Furthermore, decreased feature sizes can exacerbate coarsening effects that degrade performance. This paper discusses an alternative method for enhancing the low-temperature performance of Ni-YSZ anodes - infiltration of Gd-doped Ceria (GDC). Since GDC is introduced after the high-temperature firing, nano-scale particles can be achieved. A single-step GDC infiltration into Ni-YSZ is studied with different solution concentrations. The optimal infiltration is found to reduce polarization resistance by a factor of 3 times at 600^oC.