Development of Robust SOFC Anode Materials Using La-Doped SrTiO3

We utilize the very stable Sr_0.9La_0.1TiO₃ (SLT) to fabricate robust anode for SSZ electrolyte-supported SOFC single cell. The anode consisted of three layers: a layer of 60wt% GDC-SLT or 40wt% SSZ-SLT as functional layer and two layers of SLT as current conducting layer. Cathode was composed of a layer of 50wt% SSZ-LSM as functional layer and a layer of LSM as current conducting layer. Impregnation method was employed to decorate nano-sized Ni and CeO₂ into the ceramic anode. We measured electrochemical properties of the single cells in 3%-humidified H₂at 800°C, and investigated redox stability of the nano-sized catalyst impregnated ceramic anodes by fuel interruption method described in our previous publication.

The homogeneously dispersed nano-sized catalyst provides sufficient catalytic activity for the conductive ceramic backbones, GDC-SLT or SSZ-SLT, to work as effective anodes, and remarkable improvement of cell performance could be achieved. Compared with the traditional Ni-SSZ cermet anode, the catalyst impregnated ceramic anodes have prominent advantage against the redox cycling test. Cell performance drops 0.52% and 0.45% when using catalyst impregnated 60wt% GDC-SLT and 40wt% SSZ-SLT as anode in the first 10 redox cycles respectively, whereas, the degradation rate of Ni-SSZ in the first 10 redox cycles is 14%. The excellent stability of the impregnated anodes against redox cycling test mainly comes from two aspects: firstly, the electronic conducting path provided by ceramic backbone maintains completely during redox cycling, whereas, conducting path in traditional Ni-SSZ, the connected Ni particles, will be dislocated when Ni particles suffer shrink and expansion during redox cycling. Moreover, CeO₂used in the anode works as inhibitor preventing Ni particles from further agglomeration, meanwhile it supports Ni particles to maintain sufficient catalytic activity for fuel oxidation at constant current loading.

In conclusion, we have developed robust SLT-based ceramic anodes using impregnation method, which demonstrated excellent stability in redox cycling test compared with traditional Ni-Zirconia cermet.