Electrochemical cell with dynamic endplate

1. An electrochemical cell stack comprising:

a plurality of cells, each of said plurality of cells having a membrane and a first and second electrode, said plurality of cells generating hydrogen at a pressure;

a first static endplate coupled to said plurality of cells;

a second static endplate mounted in a fixed relationship to said first static endplate, wherein said second static endplate is opposite said first static endplate;

a third endplate mounted between said second static endplate and said plurality of cells, said third endplate movable between a first position and a second position under said pressure from said generated hydrogen; and,

a pressure chamber formed between said static endplate and said dynamic endplate, said pressure chamber being fluidly coupled to said plurality of cells.

2. An electrochemical cell stack comprising:

a plurality of cells, each of said plurality of cells having a membrane and a first and second electrode, said plurality of cells generating hydrogen at a pressure;

a first static endplate coupled to said plurality of cells;

a second static endplate mounted in a fixed relationship to said first static endplate, wherein said second static endplate is opposite said first static endplate;

a dynamic endplate mounted between said second static endplate and said plurality of cells;

a chamber formed between said static endplate and said dynamic endplate, said pressure chamber being fluidly coupled to said plurality of cells; and,

a spring arranged between said second static endplate and said dynamic endplate.

3. The electrochemical cell stack of claim 2 wherein said hydrogen pressure is greater than 400 psi.

4. The electrochemical cell stack of claim 3 wherein the dynamic endplate has a first area in contact with the spring and a second area in contact with the plurality of cells wherein the ratio of the first area to the second area is greater than 1.

5. The electrochemical cell stack of claim 4 wherein the ratio of the first area to the second area is greater than 1 and less than 3.

6. The electrochemical cell stack of claim 5 wherein the ratio of the first area to the second area is between 1.5 to 2.5.

7. The electrochemical cell stack of claim 4 wherein each of said plurality of cells includes a conduit, said conduit being fluidly coupled to each of said plurality of cells and said pressure chamber.

8. The electrochemical cell stack of claim 7 wherein said hydrogen pressure is greater than 1000 psi.

9. An electrochemical cell stack comprising:

a plurality of coaxially arranged cells, each of said cells having an anode electrode and a cathode electrode with a membrane disposed in between, said plurality of cells further having a first flow field in fluid communication with said anode electrode and a second flow field in fluid communication with said cathode electrode;

a first static endplate arranged in contact with one end of said plurality of cells;

a third endplate having an upper surface and a lower surface, said third endplate being arranged opposite said first static endplate with said lower surface being in contact with said plurality of cells;

a second static endplate coupled to said first static endplate; and,

a pressure chamber arranged between said second static endplate and said dynamic endplate;

wherein said third endplate translates independently from said second static endplate between a first position and a second position in response to a gas pressure from said pressure chamber.

10. The electrochemical cell stack of claim 9 wherein the ratio of the area of said upper surface to the area of said lower surface is greater than 1.

11. The electrochemical cell stack of claim 10 wherein the ratio of the area of said upper surface to the area of said lower surface is between 1.5 and 2.5.

12. The electrochemical cell stack of claim 11 wherein the ratio of the area of said upper surface to the area of said lower surface is 1.5.

13. The electrochemical cell stack of claim 10 further comprising a means for applying pressure to said upper surface.

14. The electrochemical cell stack of claim 13 wherein said means for applying pressure is the hydrogen gas generated by said plurality of cells.

15. The electrochemical cell stack of claim 14 wherein said means for applying pressure further includes a spring arranged in said pressure chamber.

16. The electrochemical cell stack of claim 13 further comprising a retaining ring coupled to said second static endplate and at least one spring washer wherein said retaining ring and spring washer are positioned within said pressure chamber.