Unconventional Highly Active and Stable Oxygen Reduction Catalysts Informed by Computational Design Strategies

Discovering and engineering new materials with fast oxygen surface exchange kinetics and robust long-term stability is essential for the large scale, economically viable commercialization of solid oxide fuel cell (SOFC) technology. The perovskite catalyst material BaFe_0.125Co_0.125Zr_0.75O₃ (BFCZ75) was predicted to be promising from our recent density functional theory calculations but is unconventional due to its extremely high Zr content and low electronic conductivity.[1] However, we demonstrate that it exhibits oxygen reduction reaction surface exchange rates on par with Ba_0.5Sr_0.5Co_0.8Fe_0.2O₃ (BSCF) and excellent stability at typical operating temperatures.[2] We engineer new composite electrodes integrating BFCZ75 with commercial electrode materials La_1-xSr_xMnO₃ (LSM) and La_1-xSr_xCo_yFe_1-yO₃ (LSCF) and achieve high performance as measured by low area specific resistance (ASR) values, with the LSCF/BFCZ75 ASR values comparable to top performing non-composite electrode materials such as SrCo_0.8Sc_0.2O_3-d,[3] BaNb_0.05Fe_0.95O_3-d[4] and BaCo_0.7Fe_0.22Y_0.08O_3-d.[5] Considering this result was obtained with simple mixing of commercial LSM/LSCF and as-made BFCZ75 using standard processing methods, the performance of the electrode could be even further improved by optimizing the composition and microstructure. This study successfully demonstrates that modern computational-based materials discovery methods can point to unconventional and novel SOFC electrode design strategies which would have been either inaccessible to experimental techniques (e.g., too many compositions to examine) or ill-advised based on conventional wisdom (e.g., having too low electronic conductivity by virtue of low transition metal content). These novel design strategies can unlock new high-performing SOFC electrode materials with performance rivaling other state-of-the-art novel cathode materials, while also having improved operational stability and utilizing current commercial cathode material production lines, offering a promising path toward the widespread adoption of SOFC energy technology.<br/><br/>References<br/><br/>[1] Jacobs, R., Mayeshiba, T., Booske, J., Morgan, D. Material Discovery and Design Principles for Stable, High Activity Perovskite Cathodes for Solid Oxide Fuel Cells. Advanced Energy Materials, 8 (11) (2018)<br/>[2] Jacobs, R., Liu, J., Na, B.-t., Guan, B., Yang, T., Lee, S., Hackett, G., Kalapos, T., Abernathy, H., Morgan, D., Unconventional Highly Active and Stable Oxygen Reduction Catalysts Informed by Computational Design Strategies. Advanced Energy Materials 2201203 (2022)<br/>[3] Chen, D., Chen, C., Zhang, Z., Baiyee, Z. M., Ciucci, F., Shao, Z., Compositional Engineering of Perovskite Oxides for Highly Efficient Oxygen Reduction Reactions, ACS Applied Materials and Interfaces 7, (16) (2015)<br/>[4] Dong, F., Chen, Y., Ran, R., Chen, D., Tade, M. O., Liu, S., Shao, Z., BaNb_0.05Fe_0.95O_3-d as a new oxygen reduction electrocatalyst for intermediate temperature solid oxide fuel cells, Journal of Materials Chemistry A 1 (2013).<br/>[5] He, W., Wu, X., Yang, G., Shi, H., Dong, F., Ni, M. BaCo_0.7Fe_0.22Y_0.08O_3-d as an Active Oxygen Reduction Electrocatalyst for Low-Temperature Solid Oxide Fuel Cells below 600 C, ACE Energy Letters 2 (2) (2017).