A more efficient anode microstructure for SOFCs based on proton conductors

While the desired microstructure of the state-of-the-art Ni-YSZ anode for a solid oxide fuel cell (SOFC) based on YSZ is well known, the anode microstructure for a SOFC based on a proton conductor is yet to be optimized. In this study, we examined the effect of anode porosity on the performance of a SOFC based on BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb), a mixed ion (proton and oxygen anion) conductor with high ionic conductivity at intermediate temperatures. Three cells with Ni-BZCYYb cermet anodes of different porosities (37%, 42%, and 50%) and identical electrolytes and cathode components were fabricated and tested. Under typical fuel cell operating conditions, the cell with anode of the lowest porosity (37%), prepared without pore former, achieved the highest performance, demonstrating a peak power density of 1.2 W/cm2 at 750 °C. This is radically different from the results of Ni-YSZ anodes for YSZ based cells, where high anode porosity (∼55%) is necessary to achieve high performance. The observed increase in performance (or electrocatalytic activity for anode reactions) is attributed primarily to the unique microstructure of the anode fabricated without the use of pore forming precursors.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A more efficient anode microstructure is developed for proton conducting SOFCs. ► The anode without pore former has the lowest polarization resistance. ► A peak power density of 1.2 W/cm2 at 750 °C is achieved for a proton conducting SOFC. ► The optimized microstructures of oxygen anion and proton conducting SOFCs differ.