Electrochemically influenced cation inter-diffusion and Co₃O₄ formation on La_0.6Sr_0.4CoO₃ infiltrated into SOFC cathodes

Journal Article · Thu Jun 18 00:00:00 EDT 2015 · Solid State Ionics

DOI:https://doi.org/10.1016/j.ssi.2015.05.026· OSTI ID:1259263

Song, Xueyan ^[1]; Lee, Shiwoo ^[2]; Chen, Yun ^[1]; Gerdes, Kirk ^[3]

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1. National Energy Technology Lab. (NETL), Albany, OR (United States); West Virginia Univ., Morgantown, WV (United States)
2. National Energy Technology Lab. (NETL), Albany, OR (United States)
3. West Virginia Univ., Morgantown, WV (United States)

Nanosized LSC electrocatalyst was infiltrated into a porous scaffold cathode composed of Sm₂O₃-doped CeO₂ (SDC) and La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF) in a commercial button solid oxide fuel cell (SOFC). To understand the stability of cathodes infiltrated with LSC, the infiltrated composite cells were subjected to both electrochemical operating and thermal aging states at 750 °C for 1500 h. Nanostructure and local chemistry evolution of La_0.6Sr_0.4CoO₃ (LSC) infiltrated cathodes upon operation and aging were investigated by transmission electron microscopy. After operation, the LSC remained a cubic perovskite, and the crystal grains exhibit comparable size to as-infiltrated LSC grains. Inter-diffusion of Fe from the LSCF to a Fe-incorporated LSC layer developed on the LSCF backbone. However, only sharp interfaces were observed between LSC and SDC backbone in the as-infiltrated cathode and such interfaces remain after operation. The infiltrated LSC on the SDC backbone also retains granular particle morphology. Furthermore, newly grown Co₃O₄ nanocrystals were found in the operated cathode. After thermal aging, on the other hand, cation inter-diffusion across the interfaces of the infiltrate particles and the cathode backbones is less than that from the operated cells. Lastly, the following hypothesis is proposed: Co₃O₄ forms on LSC arising from local charge balancing between cobalt and oxygen vacancies.

• Research Organization: National Energy Technology Lab. (NETL), Albany, OR (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: FE0004000
• OSTI ID: 1259263
• Report Number(s): A-CONTR-PUB-057; PII: S0167273815002337
• Journal Information: Solid State Ionics, Vol. 278, Issue C; ISSN 0167-2738
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
30 DIRECT ENERGY CONVERSION
solid oxide fuel cells
cathode infiltration
interface
cation inter-diffusion
transmission electron microscopy