Internal current collection in microtubular SOFCs: Minimisation of contact resistance via brazing and plating
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AbstractMicrotubular Solid Oxide Fuel Cells (µ-SOFC) are aptly suited for powering devices with demands ranging from the order of mW to few kW. The rapid start-up time, high thermo-mechanical stability, and excellent power density by volume lend them favour over alternate configurations, particularly for portable applications (1). Interconnecting the micro-tubes, though, is a persistent issue and minimisation of conduction pathway lengths and their contribution to stack ohmic resistance is a key parameter for maximising overall performance from a tubular cell stack (2). Contacting of each electrode is most simply and typically achieved from the cell exterior at the expense of available active electrode area. Exposing the cell support, interior electrode (anode or cathode, depending on cell configuration) from the exterior can lead to fuel crossover, decreasing fuel utilisation and giving rise to accelerated degradation from local thermal ‘hot spots’ as a result of hydrogen combustion (3). In this paper a novel method of internal current collection is proposed to collect current from multiple points along the inner wall of an anode-supported tubular cell. The current collector will also act as a flow turbuliser, enhancing the flow and reducing thermal gradients within the fuel cell. Ensuring an intimate contact of the many current collection nodes to the anode and hence minimisation of contact resistance is achieved by use of brazing, depositing braze material via electroless plating. Interconnection proficiency has been studied using electrochemical performance testing, impedance spectroscopy, optical microscopy and mechanical testing.
CitationHodjati-Pugh, O., Dhir, A. and Steinberger-Wilckens, R. (2019) Internal current collection in microtubular SOFCs: Minimisation of contact resistance via brazing and plating, ECS Transactions, 91(1), pp. 533-548.
PublisherThe Electrochemical Society
DescriptionPaper presented at the Sixteenth International Symposium on Solid Oxide Fuel Cells (SOFC-XVI), held in Kyoto, Japan, September 8–13, 2019.
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