The invention relates to an insulating element for a fuel cell stack, which is composed of a thermally insulating plastic or plastic composite material. The insulating element is connected to the end plate and the bipolar end plate of the stack and achieves virtually uniform distribution of temperature and flow density along the fuel cell stack in the cell operating mode. As a result, the condensation of product water is prevented. The efficiency of the fuel cell stack is increased since it is possible to dispense with external heating of the stack by a cell current and costly measuring and control technology,
Description
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the design of a fuel cell stack according to the invention, with at least one insulating element 1;
FIG. 2 shows an insulating plate 1 in a plan view; and
FIG. 3 shows an insulating plate 1 in section.
Claims
1. Fuel cell having two end plates (2) which hold at least one fuel cell stack in the manner of a sandwich, which fuel cell stack is composed of a sequence of a first collector plate (3), a first bipolar end plate (4), a diaphragm electrode unit (5), a number x of repeating units comprising a bipolar plate (7) and diaphragm electrode unit (6), a second bipolar end plate (4) and a second collector plate (3), x being a positive integer including 0, characterized in that the fuel cell has insulating elements (1) which are adjacent to the end plates and contain plastic.
2. Fuel cell according to claim 1, characterized in that the insulating elements (1) are at least thermal insulating elements.
3. Fuel cell according to claim 1, characterized in that the insulating elements (1) are thermal and electrical insulating elements.
4. Fuel cell according to claim 1, characterized in that the insulating elements (1) are arranged on the side of the end plates (2) facing the fuel cell stack.
5. Fuel cell according to claim 1, characterized in that the insulating elements (1) are integrated into the end plate (2).
6. Fuel cell according to claim 1, characterized in that the insulating elements (1) have a thermal conductivity of less than 1.0 W/(Km).
7. Fuel cell according to claim 1, characterized in that the insulating elements (1) constitute plates.
8. Fuel cell according to claim 7, characterized in that the thickness of the plates of the insulating elements (1) is at least 0.05 cm.
9. Fuel cell according to claim 7, characterized in that the plates have breakthroughs (8) for feeding in at least one medium.
10. Fuel cell according to claim 9, characterized in that the breakthroughs (8) have seals.
11. Fuel cell according to claim 10, characterized in that the breakthroughs (8) between the end plate (2) and insulating element (1) and/or between the insulating element (1) and the collector plate (3) can be sealed by means of the seals.
12. Fuel cell according to claim 7, characterized in that the at least one medium is a fuel and/or oxidation medium and/or a heat exchanging medium.
13. Fuel cell according to claim 12, characterized in that the plates of the insulating elements (1) are composed of at least one plastic composite material.
14. Fuel cell according to claim 13, characterized in that the at least one plastic is polytetrafluoroethylene, polyphenylene sulfide, polyimide, polyamidide, polyetheretherketone, polyetherimide, polysulfone and/or a foamed polymer.
15. Fuel cell according to claim 13, characterized in that the at least one plastic composite material is glass-fiber-reinforced or carbon-fiber reinforced polytetrafluoroethylene, glass-fiber-reinforced or carbon-fiber-reinforced polyphenylenesulfide, glass-fiber-reinforced or carbon-fiber-reinforced polyimide, glass-fiber-reinforced or carbon-fiber-reinforced polyamidimide, glass-fiber-reinforced or carbon-fiber-reinforced polyetheretherketone, glass-fiber-reinforced or carbon-fiber-reinforced polyetherimide and/or glass-fiber-reinforced and/or carbon-fiber-reinforced polysulfone.
16. Fuel cell according to claim 15, characterized in that at least the core of the at least one plastic composite material is composed of a microporous, foamed polymer.
17. Fuel cell according to claim 16, which can be used in the operating temperature range of the fuel cell stack up to 250° C.
Patent Application
20070231651
