Impact of Nickel agglomeration on Solid Oxide Cell operated in fuel cell and electrolysis modes

Long-term experiments have been carried out to investigate the impact of Nickel (Ni) coarsening on the performance of Solid Oxide Cell. Durability tests have been performed with H2 electrode supported cells at 850 °C and 750 °C in fuel cell and electrolysis modes. Microstructural changes in the comp...

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Bibliographic Details
Published in:Journal of power sources 2018-09, Vol.397, p.240-251
Main Authors: Hubert, M., Laurencin, J., Cloetens, P., Morel, B., Montinaro, D., Lefebvre-Joud, F.
Format: Article
Language:English
Subjects:
Chemical Sciences
Material chemistry
Modelling
Ni coarsening
SOEC
SOFC
Tomography
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Summary:Long-term experiments have been carried out to investigate the impact of Nickel (Ni) coarsening on the performance of Solid Oxide Cell. Durability tests have been performed with H2 electrode supported cells at 850 °C and 750 °C in fuel cell and electrolysis modes. Microstructural changes in the composite electrode of Nickel and Yttria Stabilized Zirconia (YSZ) have been characterized by synchrotron X-ray nanotomography. Analysis of the reconstructions have revealed that Ni coarsening induces a significant decrease of both the density of Triple Phase Boundary lengths (TPBls) and the Ni/gas specific surface area. However, the contact surface between Ni and YSZ is not changed upon operation, meaning the Ni sintering is inhibited by the YSZ backbone. Moreover, the Ni coarsening rate is independent of the electrode polarization. The evolution of TPBls in operation has been fitted by a phenomenological law implemented in an electrochemical model. Simulations have shown that microstructural changes in the H2 electrode explain ∼30% of the total degradation in fuel cell mode and ∼25% in electrolysis mode at 850 °C after 1000–2000 h. Moreover, it has been highlighted that the temperature at which the degradation is estimated after the durability experiment plays a major role on the result. •Typical SOCs operated under fuel cell and electrolysis currents at 750 °C and 850 °C.•Ni-YSZ cermets reconstructed by synchrotron X-ray holotomography.•The inhibiting role of the YSZ backbone on Ni coarsening experimentally highlighted.•Local Ni particle growth independent on polarization in SOFC or SOEC modes.•Impact of Ni coarsening on cell performances computed for SOFC and SOEC modes.
ISSN:0378-7753
1873-2755
DOI:10.1016/j.jpowsour.2018.06.097