Tuning Surface Stoichiometry of SOFC Electrodes at the Molecular and Nano-scale for Enhanced Performance and Durability

Technical Report · Tue Jan 19 04:00:00 EST 2021

DOI:https://doi.org/10.2172/1760426· OSTI ID:1760426

Wachsman, Eric D. ^[1]

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1. Univ. of Maryland, College Park, MD (United States); University of Maryland

This project achieved the following objectives. Different cation segregation behaviors of different common SOFC cathodes, including La_0.6Sr_0.4Co0.2Fe_0.8O_3-δ (LSCF), Sr_0.5Sm_0.5O_3-δ (SSC), and PrBa_0.5Sr_0.5Co_1.5Fe_0.5O5_+δ (PBSCF), were determined. We showed how oxygen partial pressure and gas impurities impact the stability of SOFC cathodes. We developed atomic layer deposition (ALD) coating techniques for electrodes and showed that by introducing different elements and different ALD oxidizers, electrode surface chemistry can be altered, resulting in enhanced oxygen reduction kinetics. In addition, we developed solution infiltration technique to enhance performance and durability of electrodes. Different infiltrates as well as different thermal treatment processes were screened to identify the optimal surface modification process that yields both low impedance and high durability. The modified cathode shows excellent stability and has a low area specific resistance (ASR) of only 0.2 Ωcm² at 600 °C after over 2000 hours of operation. Further, we developed ceramic anodes, SrFe(Co,Mo)O₃ (SFCM) and SrFe(Ni,Mo)O₃(SFNM), and enhanced anode oxidation kinetics by solution infiltration or in situ catalyst exsolution from the ceramic anode surface. The modified anodes showed improved performance in full SOFCs, and the optimized anode modification shows high stability for over 400 hours at 550 °C. Moreover, the modified anode also demonstrates high durability in methane. This work provides fundamental understanding of electrode surface chemistry and demonstrates a simple, facile, cost-effective approach to enhance catalytic activity and durability of SOFC electrodes.

• Research Organization: Univ. of Maryland, College Park, MD (United States)
• Sponsoring Organization: USDOE Office of Fossil Energy (FE)
• DOE Contract Number: FE0031662
• OSTI ID: 1760426
• Report Number(s): Final-Report-DOE-Univ Maryland--0031662
• Country of Publication: United States
• Language: English

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