Bus bar assembly for an electrochemical cell stack
An electrochemical cell stack assembly is disclosed comprising a member made of an elastic and electrically conductive material placed between a bus bar and a starter plate. The elastic, electrically conducting member covers at least a peripheral region along a perimeter of a recess housing the bus bar to distribute compression forces over an interface area between the bus bar and an insulator end plate, thereby reducing shear stresses in the starter plate when the stack is compressed. An elastic pad also may be arranged in the recess and between the insulator end plate and the bus bar.
1. An electrochemical cell stack comprising:
a) a bus bar having two opposite generally flat side surfaces;
b) an end plate having a recess on one side, the recess arranged to receive the bus bar so that one of the two opposite generally flat side surfaces of the bus bar is received into the recess, the end plate having a substantially flat sealing area generally surrounding the recess; and
c) an elastic material in the form of a flat sheet arranged on the other of the two opposite generally flat side surfaces of the bus bar, the elastic material extending from the bus bar to the sealing area of the end plate to cover an interface between the bus bar and the end plate.
2. The electrochemical cell stack recited in claim 1 , wherein the elastic material is formed of an electrically conducting material.
3. The electrochemical cell stack recited in claim 2 , wherein the end plate further comprises manifold through holes arranged around a periphery of the recess.
4. The electrochemical cell stack recited in claim 3 , wherein a sealing material is arranged on the end plate to provide a seal around at least one of the manifold through holes.
5. The electrochemical cell stack recited in claim 4 , further comprising a starter plate having a first flat side surface and a second flat side opposite the first flat side, wherein the starter plate defines a flow field.
6. The electrochemical cell stack recited in claim 5 , wherein the first flat side of the starter plate is arranged to abut the other of the two opposite generally flat side surfaces of the bus bar.
7. The electrochemical cell stack recited in claim 6 , further comprising a sealing material arranged on the second flat side of the starter plate to provide a seal around at least one of the manifold through holes.
8. The electrochemical cell stack recited in claim 7 , further comprising an elastic pad arranged in the recess of the end plate and between the recess and the bus bar.
9. The electrochemical cell stack recited in claim 8 , wherein the end plate comprises an insulator plate, the insulator plate comprising the recess arranged to receive the bus bar.
10. The electrochemical cell stack recited in claim 1 , wherein the end plate comprises an insulator plate that is separable from the remainder of the end plate, the insulator plate comprising the recess arranged to receive the bus bar.
11. The electrochemical cell stack recited in claim 1 , further comprising a flow field plate in contact with the elastic material.
12. The electrochemical cell stack recited in claim 11 wherein the flow field plate plate comprises graphite.
13. The electrochemical cell stack recited in claim 1 wherein the elastic material is a gas diffusion media material.
14. An electrochemical cell stack comprising:
a) a bus bar having two opposite generally flat side surfaces;
b) an end plate having a recess on one side, the recess arranged to receive the bus bar so that one of the two opposite generally flat side surfaces of the bus bar is received into the recess, the end plate having a substantially flat sealing area generally surrounding the recess; and
c) a sheet of gas diffusion layer material on the other of the two opposite generally flat side surfaces of the bus bar, the gas diffusion layer material extending from the bus bar to the sealing area of the end plate to cover an interface between the bus bar and the end plate.
15. The electrochemical cell stack of claim 14 further comprising a flow field plate adjacent to the sheet of gas diffusion layer material.
16. The electrochemical cell stack of claim 15 wherein the flow field plate is made of graphite.
17. An electrochemical cell stack comprising:
a) a bus bar having two opposite generally flat side surfaces;
b) an end plate having a recess on one side, the recess arranged to receive the bus bar so that one of the two opposite generally flat side surfaces of the bus bar is received into the recess, the end plate having a substantially flat sealing area generally surrounding the recess;
c) an elastic material arranged on the other of the two opposite generally flat side surfaces of the bus bar, the elastic material extending from the bus bar to the sealing area of the end plate to cover an interface between the bus bar and the end plate; and,
d) a graphite flow field plate adjacent to the elastic material.