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Towards High Power Density Metal Supported Solid Oxide Fuel Cell for Mobile Applications

Friday, 28 July 2017: 15:20
Atlantic Ballroom 1/2 (The Diplomat Beach Resort)
J. Nielsen, A. H. Persson, T. T. Muhl, and K. Brodersen (DTU Energy, Technical University of Denmark)
Solid oxide fuel cell (SOFC) is attractive due to the excellent power generation efficiency and fuel flexibility. Conventional ceramic electrolyte and anode supported SOFC (AS-SOFC) is limited to stationary power generation applications as a result of the difficulty of quick startup and the high operating temperatures of 700 to 1000 °C. If quick startup of a SOFC is realized, mobile applications may be considered. To enable this, it is important to shorten the start-up time and reduce the heat cycle performance degradation and stack power density both in terms of weight and volume. As an approach to solving these problems, metal supported SOFC (MS-SOFC) has attracted attention. The development of this new generation of SOFC is currently in progress. DTU Energy’s MS-SOFC technology is based on co-sintering of laminated tape casted electrolyte, anode and support layers in a reducing atmosphere. This implies that the sintering shrinkage of the different layers should be matched sufficiently so that the mechanical stresses originating from any mismatch in sintering shrinkage of the individual layers during sintering can be absorbed by the cell structure. If the cell structure is unable to absorb the mechanical stresses, the cell will crack. Perfect matching of sintering shrinkage of the layers is practically very difficult as e.g. the electrolyte layer needs to be completely dense and thus gas tight, while the anode and support layers in contrast needs to be highly porous to allow sufficient gas transport. In the present study, we report on efforts of reducing the metal support thickness in DTU Energy´s MS-SOFC design. This is done to reduce the stack thermal mass during heat up and to increase the stack power density in terms of weight and volume. The results show an increased densification of the metal support layer as the support layer thickness is gradually reduce from 313 μm to 108 μm. This is due to sintering constraint. To counteract the metal support layer densification, the feasibility of creating gas channels within the support layer is explored. The gas channels are in this particular approach prepared by the creation of holes in the green tape casted support layer via puncturing. The study shows, that it is possible to lower the support thickness and thus the cell thickness. The study also shows that it is possible to counteract the increased support layer densification and resulting performance loss by the creation of gas channels in the support layer.