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Title: Effect of Ni content on the morphological evolution of Ni-YSZ solid oxide fuel cell electrodes

The coarsening of Ni in Ni–yttria-stabilized zirconia (YSZ) anodes is a potential cause of long term solid oxide fuel cells (SOFC) performance degradation. The specifics of the Ni-YSZ structure—including Ni/YSZ ratio, porosity, and particle size distributions—are normally selected to minimize anode polarization resistance, but they also impact long-term stability. A better understanding of how these factors influence long-term stability is important for designing more durable anodes. The effect of structural details, e.g., Ni-YSZ ratio, on Ni coarsening has not been quantified. Furthermore, prior measurements have been done by comparing evolved structures with control samples, such that sample-to-sample variations introduce errors. Here in this paper, we report a four dimensional (three spatial dimensions and time) study of Ni coarsening in Ni-YSZ anode functional layers with different Ni/YSZ ratios, using synchrotron x-ray nano-tomography. The continuous structural evolution was observed and analyzed at sub-100 nm resolution. It is shown quantitatively that increasing the Ni/YSZ ratio increases the Ni coarsening rate. This is due to both increased pore volume and a decrease in the YSZ volume fraction, such that there is more free volume and a less obtrusive YSZ network, both of which allow greater Ni coarsening. The results are shown to be inmore » good agreement with a power-law coarsening model. In conclusion, the finding is critical for informing the design of SOFC electrode microstructures that limit coarsening and performance degradation.« less
Authors:
 [1] ;  [2] ;  [2] ;  [2] ;  [1]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source II
  2. Northwestern Univ., Evanston, IL (United States). Department of Materials Science and Engineering
Publication Date:
Report Number(s):
BNL-112539-2016-JA
Journal ID: ISSN 0003-6951
Grant/Contract Number:
SC00112704; AC02-98CH10886
Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 108; Journal Issue: 8; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1340378
Alternate Identifier(s):
OSTI ID: 1239446