期刊
JOURNAL OF POWER SOURCES
卷 386, 期 -, 页码 1-9出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jpowsour.2018.03.025
关键词
Fuel cells; Electrodes; Microstructures; Porous materials; Composite materials
资金
- National Energy Technology Laboratory's ongoing research in solid oxide fuel cells under RES contract [DE-FE0004000]
- Internship/Research Participation Program at the National Energy Technology Laboratory, U.S. Department of Energy
- National Science Foundation [DMR 1428480]
- CMU ProSEED/EQT Foundation Grant
- [MCF-677785]
The performance of electrochemical devices depends on the three-dimensional (3D) distributions of micro structural features in their electrodes. Several mature methods exist to characterize 3D microstructures over the microscale (tens of microns), which are useful in understanding homogeneous electrodes. However, methods that capture mesoscale (hundreds of microns) volumes at appropriate resolution (tens of nm) are lacking, though they are needed to understand more common, less ideal electrodes. Using serial sectioning with a Xe plasma focused ion beam combined with scanning electron microscopy (Xe PFIB-SEM), two commercial solid oxide fuel cell (SOFC) electrodes are reconstructed over volumes of 126 x 73 x 12.5 and 124 x 110 x 8 mu m(3) with a resolution on the order of approximate to 50(3) nm(3). The mesoscale distributions of microscale structural features are quantified and both microscale and mesoscale inhomogeneities are found. We analyze the origin of inhomogeneity over different length scales by comparing experimental and synthetic microstructures, generated with different particle size distributions, with such synthetic microstructures capturing well the high-frequency heterogeneity. Effective medium theory models indicate that significant mesoscale variations in local electrochemical activity are expected throughout such electrodes. These methods offer improved understanding of the performance of complex electrodes in energy conversion devices.
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