Solid oxide fuel cell with sealed structure
This invention relates to the presence of slightly or non-porous zones in the electrode layer around gas inlets, in order to improve the leak tightness between the different individual cells making up a fuel cell with a plane geometry. The fuel cell comprises a first electrode layer having a non-porous zone forming a passage therethrough for gas flow and an electrolyte layer having a protuberance which extends into the first electrode layer for forming the non-porous zone with the non-porous zone representing a gas tight passage. Nested contact between the bipolar plate and the ceramic triple layer making up the basic cell is also described and is another possible means of avoiding mixes of gasses.
1. An individual cell for a fuel cell having a stack of cells with each individual cell comprising:
a first electrode layer having a first porosity;
a second electrode layer having a second porosity;
a solid electrolyte layer located between said first and second electrode layers;
a first bipolar plate adjacent to the first electrode layer;
a second bipolar plate adjacent to the second electrode layer;
a first gas inlet;
a second gas inlet;
wherein the first electrode layer comprises a first non-porous zone forming a passage therethrough for gas flow from the first gas inlet;
wherein said electrolyte layer has a protuberance which extends into the first electrode layer forming said first non-porous zone with the first non-porous zone representing a gas tight passage;
wherein at least one of the two bipolar plates has a coefficient of thermal expansion higher than the coefficient of thermal expansion of the adjacent electrode layer and the electrolyte layer,
wherein said one bipolar plate with said high coefficient of thermal expansion comprises at least a protuberance and the electrode layer adjacent thereto comprising a cavity with the protuberance of the one bipolar plate and the cavity in the adjacent electrode fitting into one another and
wherein said one bipolar plate being connected to the adjacent electrode layer by nesting.
2. An individual cell for a fuel cell according to claim 1 , wherein the first electrode layer has a first thickness and said first non-porous zone has a thickness identical to the first thickness.
3. An individual cell for a fuel cell according to claim 1 , wherein the second electrode layer comprises a second non-porous zone forming a passage for gas flow from the second gas inlet and wherein said electrolyte layer has a protuberance which extends into the second electrode layer forming said second non-porous zone with said second non-porous zone representing a gas tight passage.
4. An individual cell for a fuel cell according to claim 3 , wherein the second electrode layer has a second thickness, and the a second non-porous zone has a thickness identical to the second thickness.
5. An individual cell for a fuel cell according to claim 1 , wherein said one bipolar plate is located adjacent to the first or second electrode layer.
6. An individual cell for a fuel cell according to claim 1 , wherein the cavity is located in the protuberance of the electrolyte layer.
7. An individual cell for a fuel cell according to claim 6 , wherein the protuberance of the electrolyte layer comprises a plurality of cavities.
8. An individual cell for a fuel cell according to claim 1 , wherein the cavity in the adjacent electrode layer being larger in width than the corresponding width of the protuberance of the bipolar plate and/or the depth of the cavity is larger than the corresponding height of the protuberance of the bipolar plate.
9. An individual cell for a fuel cell according to claim 1 , with either said first or second bipolar plate being located in the cell for separating the cell from an adjacent cell in said stack of cells.
10. An individual cell for a fuel cell according to claim 1 , wherein the fuel cell has a circular plane geometry.
11. An individual cell for a fuel cell having a stack of cells with each cell comprising:
an anode layer,
a cathode layer,
a solid electrolyte layer located between the anode layer and the cathode layer, and
with the fuel cell comprising:
a first gas inlet;
a second gas inlet;
wherein said anode layer comprises a non-porous zone forming a passage for gas flow from the first gas inlet;
wherein said cathode layer comprises another non-porous zone forming a passage for gas flow from the second gas inlet;
a first bipolar plate adjacent to the anode layer and having at least one protuberance extending in the anode layer;
a second bipolar plate adjacent to the cathode layer and having at least one protuberance extending in the cathode layer; and
wherein the anode layer further comprises a cavity formed in its non-porous zone and in which the corresponding protuberance of the first bipolar plate can fit, and the cathode layer comprises a cavity formed in its non-porous zone in which the corresponding protuberance of the second bipolar plate can fit.