Hierarchical dual-porosity nanoscale nickel cermet electrode with high performance and stability
File(s)
Author(s)
Chen, Jingyi
Wang, Xin
Boldrin, Paul
Brandon, Nigel P
Atkinson, Alan
Type
Journal Article
Abstract
Nano-structured metal-ceramic materials have attracted attention to improve performance in energy conversion applications. However, they have poor long-term stability at elevated temperatures due to coarsening of the metal nanoparticles. In this work we show that this can be mitigated by a novel design of the nano-structure of Ni cermet fuel electrodes for solid oxide cells. The strategy is to create a dual porosity microstructure, without the use of fugitive pore-formers, with micron-size pores to facilitate gas transport and nanoscale pores to control nano-particle coarsening. This has been achieved using a continuous hydrothermal synthesis and two-stage heat treatments to produce electrodes with micron size agglomerates of nano-structured porous Ni-Yttria-Stabilised-Zirconia (YSZ). This unique hierarchical microstructure combines enhanced electrochemical reaction in the high activity (triple phase boundary density 11 μm-2) nanoscale regions with faster gas diffusion in the micron-sized pores. The electrodes are aged at 800 °C in humidified 5% H2-N2 for up to 600 h. The electrochemical reaction resistance is initially 0.17 Ω cm2 but later reaches a steady long-term value of 0.15 Ω cm2. 3-D reconstruction of the electrodes after 10 h and 100 h of ageing reveals an increase in YSZ network connectivity and TPB percolation. This improvement is well-correlated to the 3-D tomography parameters using a physical model adapted from mixed conducting SOC air electrodes, which is also supported, for the first time, by numerical simulations of the microstructural evolution. These also reveal that in the long term, nickel coarsening is inhibited by the nanoscale entanglement of Ni and YSZ in the hierarchical microstructure.
Date Issued
2019-10-14
Date Acceptance
2019-09-05
Citation
Nanoscale, 2019, 11 (38), pp.17746-17758
ISSN
2040-3364
Publisher
Royal Society of Chemistry
Start Page
17746
End Page
17758
Journal / Book Title
Nanoscale
Volume
11
Issue
38
Copyright Statement
© 2019 The Royal Society of Chemistry.
Sponsor
Engineering & Physical Science Research Council (EPSRC)
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/31549698
Grant Number
EP/M014045/1
Subjects
10 Technology
02 Physical Sciences
03 Chemical Sciences
Nanoscience & Nanotechnology
Publication Status
Published
Coverage Spatial
England
Date Publish Online
2019-09-11