Correlation between triple phase boundary and the microstructure of Solid Oxide Fuel Cell anodes: The role of composition, porosity and Ni densification

Xuekun Lu, Thomas M.M. Heenan, Josh J. Bailey, Tao Li, Kang Li, Daniel J.L. Brett, Paul R. Shearing*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)
5 Downloads (Pure)

Abstract

This study aims to correlate the active triple phase boundaries (TPBs) to the variation of as-prepared anode microstructures and Ni densifications based on the reconstructed 3D volume of an SOFC anode, providing a point of comparison with theoretical studies that reveal the relationship of TPBs and the material microstructure using randomly packed spheres models. The TPB degradation mechanisms are explained using a particle network model. The results indicate that in low porosity regime, the TPBs sharply increase with the porosity until the percolation threshold (10%); at intermediate porosity (10%–25%), a balance of surface area between three phases is more critical than that of volume fraction to reach the optimal TPB density; in the high porosity regime (>25%), the TPBs start to drop due to the shrinkage and detachment of Ni/YSZ interfaces. The TPB density is inversely proportional to the degree of Ni densification as long as the Ni content is above the percolation threshold (35%) and can be improved by 70% within 7% change of porosity provided that the over-densification is mitigated. This has implications for the design of SOFC microstructures as well for electrode durability, where Ni agglomeration is known to deleteriously impact long-term operation.

Original languageEnglish
Pages (from-to)210-219
Number of pages10
JournalJournal of Power Sources
Volume365
Early online date19 Sep 2017
DOIs
Publication statusPublished - 15 Oct 2017
Externally publishedYes

Bibliographical note

Funding Information:
The authors acknowledge the support from the EPSRC under grants EP/N032888/1 , EP/P009050/1 and EP/M014045/1 , Paul R Shearing acknowledges funding from the Royal Academy of Engineering .

Publisher Copyright:
© 2017

Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.

Keywords

  • Electrode composition
  • Ni sintering
  • Particle network
  • Porosity
  • TPB degradation
  • X-ray tomography

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Physical and Theoretical Chemistry
  • Electrical and Electronic Engineering

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