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Three-dimensional microstructural changes in the Ni-YSZ solid oxide fuel cell anode during operation


 
 
Contact   Faes Antonin
 
Title   Three-dimensional microstructural changes in the Ni-YSZ solid oxide fuel cell anode during operation
 
Author(s)   Nelson G.J., Grew K.N., Izzo J.R. Jr., Lombardo J.J., Harris W.M., Faes A., Hessler-Wyser A., Van herle J., Wang S., Chu Y.S., Virkar A.V., Chiu W.K.S.
 
References   Acta Materialia, Volume 60, Issue 8, May 2012, pp. 3491-3500
 
Url   http://www.sciencedirect.com/science/article/pii/S1359645412001498
 
Abstract   Microstructural evolution in solid oxide fuel cell (SOFC) cermet anodes has been investigated using X-ray nanotomography along with differential absorption imaging. SOFC anode supports composed of Ni and yttria-stabilized zirconia (YSZ) were subjected to extended operation and selected regions were imaged using a transmission X-ray microscope. X-ray nanotomography provides unique insight into microstructure changes of all three phases (Ni, YSZ, pore) in three spatial dimensions, and its relation to performance degradation. Statistically significant 3D microstructural changes were observed in the anode Ni phase over a range of operational times, including phase size growth and changes in connectivity, interfacial contact area and contiguous triple phase boundary length. These observations support microstructural evolution correlated to SOFC performance. We find that Ni coarsening is driven by particle curvature as indicated by the dihedral angles between the Ni, YSZ and pore phases, and hypothesize that growth occurs primarily by means of diffusion and particle agglomeration constrained by a pinning mechanism related to the YSZ phase. The decrease in Ni phase size after extended periods of time may be the result of a second process connected to a mobility-induced decrease in the YSZ phase size or non-uniform curvature resulting in a net decrease in Ni phase size.
 
 
 
 
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