Fuel cell stack and electronic device provided with the same
Provided is a fuel cell stack having reduced thickness and weight and an improved output density. The fuel cell stack according to the present invention includes two or more stacked fuel cell layers, and is characterized in that at least one of the fuel cell layers is formed by arranging two or more composite unit cells in an identical plane with a gap provided therebetween, that the composite unit cell includes a plurality of unit cells and a fuel supply portion for supplying fuel to anode electrodes of the unit cells, and that the anode electrodes of the plurality of unit cells are arranged to face the fuel supply portion.
1. A fuel cell stack, comprising:
two or more stacked fuel cell layers,
said fuel cell stack being formed by alternately stacking said fuel cell layers and spacer layers each including one or more spacers,
at least one of said fuel cell layers being formed by arranging two or more composite unit cells in an identical plane with a gap provided therebetween,
at least one of said spacer layers being formed by arranging two or more spacers in an identical plane with a gap provided therebetween,
the gap formed by said two or more composite unit cells being a space penetrating the fuel cell layer in a direction of layer thickness thereof and communicating with the gap formed by said two or more spacers,
said composite unit cell including a plurality of unit cells, each having an anode electrode, a cathode electrode and an electrolyte membrane, and a fuel supply portion for supplying fuel to the anode electrodes of said unit cells,
the anode electrodes of said plurality of unit cells being arranged to face said fuel supply portion.
2. The fuel cell stack according to claim 1 , wherein said spacer is provided on each of both end portions of either one or both of front and rear surfaces of said fuel cell layer.
3. The fuel cell stack according to claim 1 , wherein said spacer layer is one large-area spacer that is in contact with all the composite unit cells constituting the fuel cell layer adjacent to the spacer layer.
4. The fuel cell stack according to claim 1 , wherein said fuel supply portion includes a fuel flow channel through which the fuel flows.
5. The fuel cell stack according to claim 1 , wherein said unit cell includes the anode electrode, the electrolyte membrane, and the cathode electrode in this order.
6. The fuel cell stack according to claim 5 , wherein said unit cell has an anode current collector on a surface of said anode electrode opposite to its surface in contact with said electrolyte membrane, and has a cathode current collector on a surface of said cathode electrode opposite to its surface in contact with said electrolyte membrane.
7. The fuel cell stack according to claim 4 , further comprising a fuel permeation suppressing layer between said fuel flow channel and said anode electrode.
8. The fuel cell stack according to claim 1 , comprising a vaporization layer for supplying vapor of said fuel to said anode electrode, between said fuel supply portion and said anode electrode.
9. The fuel cell stack according to claim 6 , comprising a moisturization layer for holding water produced by power generation within said unit cell, on a side of said cathode current collector opposite to its side in contact with said cathode electrode.
10. The fuel cell stack according to claim 6 , comprising a heat insulating layer on a side of said anode current collector opposite to its side in contact with said anode electrode.
11. The fuel cell stack according to claim 1 , having a space penetrating layers constituting said composite unit cell in a thickness direction,
wherein said space is a produced gas exhaust path for exhausting produced gas produced at the anode electrodes.
12. The fuel cell stack according to claim 1 , wherein said spacer has insulating properties at least in a thickness direction thereof.
13. The fuel cell stack according to claim 1 , wherein said spacer has insulating properties at least in a surface thereof.
14. The fuel cell stack according to claim 1 , wherein said spacer is made of a porous body.
15. The fuel cell stack according to claim 1 , wherein said spacer is made of a metal oxide porous body composed of titanium oxide, aluminum oxide, or zirconium oxide insulated by an oxide, a metal-polymer composite body insulated by applying or modifying a hydrophilic polymer or attaching a hydrophilic polymer film on a surface of a metal porous body, or a porous ceramic.
16. The fuel cell stack further comprising a casing covering an outer surface of the fuel cell stack according to claim 1 , wherein said casing is in contact with said one or more spacers.
17. The fuel cell stack according to claim 16 , wherein said casing is made of one or more materials selected from the group consisting of Cu, Al, Fe, Ti, and stainless.
18. The fuel cell stack according to claim 6 , wherein two unit cells included in said composite unit cell are connected in parallel by electrically connecting two said anode current collectors included in said fuel cell layer and electrically connecting two said cathode current collectors included in said fuel cell layer.
19. The fuel cell stack according to claim 6 , wherein two adjacent said fuel cell layers are connected in series by electrically connecting said cathode current collector in one of two adjacent said fuel cell layers and said anode current collector in the other fuel cell layer.
20. The fuel cell stack according to claim 6 , wherein
said anode current collector includes an anode current collector through-hole penetrating in a thickness direction thereof,
said cathode current collector includes a cathode current collector through-hole penetrating in a thickness direction thereof,
said anode current collector through-hole and said cathode current collector through-hole are provided in an identical fuel cell layer, at different positions in a layer-stacking direction of the fuel cell layer,
said cathode current collector through-hole in one of two adjacent said fuel cell layers and the anode current collector through-hole in the other fuel cell layer are provided at a substantially identical position in a direction in which the fuel cell layers are stacked, and
the anode current collector through-hole in said one fuel cell layer and the cathode current collector through-hole in said other fuel cell layer are provided at a substantially identical position in the direction in which the fuel cell layers are stacked.
21. The fuel cell stack according to claim 1 , wherein said composite unit cell and/or said spacer are/is in a shape of an elongated strip.
22. An electronic device provided with the fuel cell stack according to claim 1 .