Electrochemical reaction unit having a single cell including a current collector having a protrusion coated with an electrically conductive coat in contact with a cathode via a bonding layer and fuel cell stack
An electrochemical reaction unit containing a single cell including an electrolyte layer containing solid oxide, and a cathode and an anode which face each other in a first direction with the electrolyte layer intervening therebetween; a current collector disposed on a cathode side of the single cell and having a protrusion protruding toward the cathode; an electrically conductive coat covering a surface of the current collector; and an electrically conductive bonding layer bonding the cathode and the protrusion covered with the coat. In at least one section of the protrusion taken in parallel with the first direction, the protrusion covered with the coat has a covered portion covered with the bonding layer and an exposed portion exposed from the bonding layer and including a corner portion of the protrusion covered with the coat.
1. An electrochemical reaction unit comprising:
a single cell including an electrolyte layer containing solid oxide, and a cathode and an anode which face each other in a first direction with the electrolyte layer intervening therebetween;
a current collector disposed on a cathode side of the single cell and having a protrusion protruding toward the cathode;
an electrically conductive coat covering a surface of the current collector including the protrusion; and
an electrically conductive bonding layer bonding the cathode and the protrusion covered with the coat at a distal end portion of the protrusion;
the electrochemical reaction unit being characterized in that in at least one section of the protrusion taken in parallel with the first direction, the protrusion covered with the coat has a covered portion covered with the bonding layer and an exposed portion exposed from the bonding layer, the exposed portion including a corner portion of the distal end portion of the protrusion covered with the coat.
2. An electrochemical reaction unit according to claim 1 , wherein respective sections of the protrusion taken in parallel with the first direction include sections where the protrusion covered with the coat has the covered portion and sections where the protrusion covered with the coat has the exposed portion.
3. An electrochemical reaction unit according to claim 2 , wherein
the current collector has a plurality of the protrusions, and
respective sections of each of the plurality of protrusions taken in parallel with the first direction; include sections where the protrusion covered with the coat has the covered portion and sections where the protrusion covered with the coat has the exposed portion.
4. An electrochemical reaction unit according to claim 1 , wherein a contact area of the bonding layer with the cathode is smaller than a contact area of the bonding layer with the protrusion covered with the coat.
5. An electrochemical reaction unit according to claim 1 , wherein a contact area of the bonding layer with the cathode is greater than a contact area of the bonding layer with the protrusion covered with the coat.
6. An electrochemical reaction unit according to claim 1 , wherein the bonding layer is formed of a spinel oxide.
7. An electrochemical reaction unit according to claim 6 , wherein the bonding layer is formed of a spinel oxide which contains at least one of Zn, Mn, Co, and Cu.
8. An electrochemical reaction unit according to claim 1 , wherein the electrolyte layer, the cathode, and the anode have a flat-plate shape.
9. An electrochemical reaction unit according to claim 1 , wherein the electrochemical reaction unit is a fuel cell electricity generation unit for generating electricity.
10. A fuel cell stack comprising a plurality of fuel cell electricity generation units, wherein at least one of the plurality of fuel cell electricity generation units is an electrochemical reaction unit according to claim 9 .