In 1987 work on Solid Oxide Fuel Cells (SOFC) R&D began in the JOULE programme, with the development of small SOFC cells. This research has now reached a stage where kW-size SOFC systems can be constructed on a variety of concepts. In this project the objective is to develop a multi-plate fuel cell with a power density of not less than 1 kW/m2 and demonstrate that it will operate for 100 hrs with hydrogen fuel and air.
The maximum power density that could be obtained from the 5x5 cm composite plate, which had three cells in series, was 452 W/m2, which is only 45% of the target power output. This poor power output could be traced to the low open circuit voltages. The maximum voltage achieved was 2.34 V. These low voltages were believed to result primarily from current leakage around the interconnect domains and were associated with overlap and short-circuiting of the electrodes of adjacent cells. It was established that these types of problems resulted from inherent flaws in the composite plate design concept: perfect co-sintering of the electrolyte and interconnect materials to give a gas tight seal could not be achieved.
Initial work will concentrate on the development of a 5cm x 5cm plate with the target power density. Fabrication (ICT) will be achieved via a co-sintered composite or yttrium stabilized zirconia with lanthanum chromile as the interconnect. Physical parameters of the powder constituents will be varied to optimize the co-sintering process.
Spraying (RISOE) and dip-coating techniques (TNO) will be investigated to deposit the electrodes onto the bare plates. Performance of the complete plates will then be evaluated in air and hydrogen (BG, IST), and tests will also be conducted with H2O/CH4 fuel to assess possible effects from internal reforming (BG).
Mathematical modelling techniques (BNFL) will be used throughout the work to optimize the various design parameters.
After 4 months, manufacture of the plates will be transferred from manual to machine processes. Alternative production methodologies will also be investigated (DSM).
If the target power density is achieved with a 5cm x 5cm plate within 12 months of the start of the project the plate size will be scaled up to 10cm x 5cm.
Funding SchemeCSC - Cost-sharing contracts
WA3 6AS Warrington
W14 0QL London