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DEVELOPMENT OF CO FIRED CERAMIC CELLS FOR LOW TEMPERATURE 800øC SOLID OXIDE FUEL CELL (SOFC) OPERATION

Objective


New ceramic cell structures were realized by co-firing various two and/or three layer systems. These laminated multi layers were fabricated using a novel, ceramic powder filled thermoplastic (CPFT or Solufil (TM)). The development was divided into different sub tasks:
development of a self supporting two layer electrolyte system with electrical losses < 100 mV at 800 C and 300 mA/cm{2}.
development of an electrode (fuel or air) supported electrolyte structure.
development of an integrated PEN, consisting of a three layer, co-fired laminate structure of a thin state of the art electrolyte, supported by thicker electrodes on both sides.

The latter structure offers an attractive, cost effective fabrication process, because lamination is easy and process steps are minimized. Nevertheless, this integrated PEN structure implements a development process with high risks. In addition, for the technical application of this new ceramic cell structures special high temperature sealing materials were developed.

It was shown in the project that any of the powders, necessary for the preparation of SOFC components could be dispersed in Solufil (TM) and resulted in sintering shrinkage matched single layer SOFC components. Also, sintered double layer electrolytes of TZP/CSZ and GCO/CSZ were demonstrated as 5x5 cm{2} electrolytes, which were cell tested at 800 C. Cell performance around 0.2 W/cm{2} were demonstrated. The development of electrode supported thin electrolyte double-layers was demonstrated with the Solufil(TM) process. Small circular sample were sintered and cell tested. A performance of 0.15 W/cm{2} was observed for the cathode supported electrolyte at 800 C. Three-layer, co-fired cells were also manufactured. Due to residual mechanical stresses in the samples, no successful cell-test could be carried out. Tape-cast analogies of the Solufil(TM) samples yielded 0.3 W/cm{2}, showing the feasibility of the concept. For cell testing of the co-fired cell, a tailor made sealant, which resulted from the project, was used. This sealant was capable of forming hermetic seals to thick electrodes.
The proposed research is directed at developing ceramic cell structures (PEN : Positive/Electrolyte/ Negative),which will be fabricated by co-firing alaminate three-layer system made of a novel, ceramic-powder-filled thermoplast (CPFT).The proposed fabrication technique offers the possibility to minimize electrical losses in the PEN, by using thin electrolytes or by using alternative, highly conducting electrolyte materials, whereas co-firing of laminated PEN's is a novel fabrication procedure. The resulting PEN's will be used in SOFC reactors, which offers the economic benefit of low operation temperature (800 C).It is anticipated, that exploitation of the results will lead to lower system costs and longer life-times for SOFC systems.

The major research tasks are:

1. Basic CPFT experiments with one-layer SOFC components.
2. Sintering experiments with one layer SOFC components.
3. -Co-firing of two-layer electrolytes with high conduction.
4. Co-firing of two-layer electrode-supported electrolytes(PE or NE)
5 Co-firing of three-layer structures (integrated PEN)

The output of every task can result in an improved PEN structure, by conventionally adding the missing PEN element(s).Successful completion of task 3,4 and 5 offers the possibility of low temperature operation of an SOFC power plant, which gives a view on the required reduction of SOFC system costs in the order of 30%.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

SIEMENS AG
Address
Otto-hahn-ring 6
91050 München
Germany

Participants (5)

DSM RESINS NV
Netherlands
Address
Het Overloon 1 P.o. Box 6500
6411 TE Heerlen
GEC Alsthom Ltd
United Kingdom
Address
Lichfield Road
ST17 4LN Stafford
IMPERIAL COLLEGE OF SCIENCE, TECHNOLOGY AND MEDICINE
United Kingdom
Address
Royal School Of Mines, Prince Consort Road
SW7 2BP London
NETHERLANDS ENERGY RESEARCH FOUNDATION
Netherlands
Address
Westerduinweg 3
1755 LE Petten
UNIV AVEIRO
Portugal
Address
Campus Universitario, Santiago
3800 Aveiro