Fuel cell stack assembly

Patent metadata

Field	Value
Publication number	US-9774056-B2
Application number	US-201314397780-A
Country	US
Kind code	B2
Filing date	Apr 30, 2013
Priority date	May 1, 2012
Publication date	Sep 26, 2017
Grant date	Sep 26, 2017

Abstract

A fuel cell stack assembly comprises a plurality of fuel cells in a stack, the stack defining two opposing parallel end faces. An end plate is disposed at each opposing end face of the stack. Each end plate defines a compression surface adjacent to and in compressive relationship with a respective one of the two opposing parallel end faces. A coupling mechanism is attached to the end plates to thereby maintain the fuel cells in the stack under compression. At least one, preferably both, of the end plates comprise a preformed element defining the compression surface, the preformed element being configured with a predetermined curvature such that the compression surface is a convex surface when the preformed element is not under load whereas, under the application of the load to maintain the fuel cells under compression, flexure of the preformed element between elements of the coupling mechanism causes the compression surface to become a substantially planar surface. This provides uniform pressure distribution across the end faces of the fuel cell stack using fewer and lighter weight components.

First claim

The invention claimed is:

1. An open cathode fuel cell stack assembly comprising:
a plurality of fuel cells in an open cathode fuel cell stack, the stack defining two opposing parallel end faces and including open air flow faces providing an air inlet face and an air outlet face of the stack, the stack further including fluid flow paths between the air inlet face and the air outlet face;
an end plate at each opposing end face of the stack, each end plate defining a compression surface adjacent to and in compressive relationship with a respective one of the two opposing parallel end faces; and
a coupling mechanism attached to the end plates to thereby maintain the fuel cells in the stack under compression, the coupling mechanism comprising two C-shaped clips configured to leave exposed the full surface area of the open air flow faces to promote uniform and laminar air flow and air distribution over a cathode electrode of the open cathode fuel cell stack;
wherein at least one of the end plates comprises a preformed element defining the compression surface, the preformed element being configured with a predetermined curvature such that the compression surface is a convex surface when the preformed element is not under load whereas, under the application of the load to maintain the fuel cells under compression, flexure of the preformed element between elements of the coupling mechanism causes the compression surface to become a substantially planar surface.

2. The open cathode fuel cell stack assembly of claim 1 in which each C-shaped clip includes an engagement member configured to engage with one of a pair of opposing edges of the preformed element, and each C-shaped clip is configured to extend along the respective edge of the preformed element.

3. The open cathode fuel cell stack assembly of claim 2 in which each C-shaped clip extends along a substantial proportion of the respective edge of the preformed element.

4. The open cathode fuel cell stack assembly of claim 2 in which the preformed element has a recess in the surface adjacent to each of the pair of opposing edges for engagement with and retention of a respective one of the C-shaped clips.

5. The open cathode fuel cell stack assembly of claim 2 in which the compression surface of the preformed element is convex along a line extending between said pair of opposing edges and is planar along a line extending parallel with said pair of opposing edges.

6. The open cathode fuel cell stack assembly of claim 2 in which each C-shaped clip exhibits elastic behaviour sufficient to enable a snap fit of the C-shaped clip onto a respective recessed edge of the preformed element.

7. The open cathode fuel cell stack assembly of claim 6 in which each C-shaped clip extends in a plane orthogonal to the parallel end faces of the stack and each C-shaped clip is configured to exhibit said elastic behaviour to flex out of said plane.

8. The open cathode fuel cell stack assembly of claim 6 in which each C-shaped clip extends along a longitudinal axis between planes defined by the parallel end faces of the stack, and each C-shaped clip is configured to exhibit said elastic behaviour to stretch along the longitudinal axis.

9. The open cathode fuel cell stack assembly of claim 8 in which each C-shaped clip comprises a meander structure along the longitudinal axis configured to provide elasticity along the longitudinal axis.

10. The open cathode fuel cell stack assembly of claim 1 in which both of said end plates comprise a preformed element as defined in any preceding claim.

11. A method of assembling an open cathode fuel cell stack assembly comprising:
layering a plurality of fuel cells in an open fuel cell stack, the stack defining two opposing parallel end faces and including open air flow faces providing an air inlet face and an air outlet face of the stack, the stack further including fluid flow paths between the air inlet face and the air outlet face;
disposing an end plate at each opposing end face of the stack, each end plate defining a compression surface adjacent to a respective one of the two opposing parallel end faces, in which at least one of the end plates is a preformed element with a predetermined curvature such that the compression surface is a convex surface when the preformed element is not under load; and
attaching a coupling mechanism to the end plates to thereby bring the end plate compression surfaces into compressive relationship with the opposing parallel end faces of the stack and thereby maintain the fuel cells in the stack under compression, the application of the load causing flexure of the at least one preformed element causing the compression surface to become a substantially planar surface under the load of the assembled stack assembly,
wherein the coupling mechanism comprises two C-shaped clips configured to leave exposed the full surface area of the open air flow faces to promote uniform and laminar air flow and air distribution over a cathode electrode of the open cathode fuel cell stack.

12. The open cathode fuel cell stack assembly of claim 1
wherein each C-shaped clip extends along a longitudinal axis between planes defined by the parallel end faces of the stack, and each C-shaped clip is configured to exhibit said elastic behaviour to stretch along the longitudinal axis.

13. The open cathode fuel cell stack assembly of claim 12 in which each C-shaped clip comprises a meander structure along the longitudinal axis configured to provide elasticity along the longitudinal axis.

14. The open cathode fuel cell stack assembly of claim 1 , wherein the convex surface has convexity in two dimensions.

15. The open cathode fuel cell stack assembly of claim 14 , wherein the two dimensions are orthogonal to one another.

16. The open cathode fuel cell stack assembly of claim 1 , in which the fuel cell stack assembly is an air cooled open cathode fuel cell stack assembly.

17. The open cathode fuel cell stack assembly of claim 1 , wherein:
each C-shaped clip includes an engagement member configured to engage with one of a pair of opposing edges of the preformed element, and each C-shaped clip is configured to extend along the respective opposing edge of the preformed element while leaving exposed corner portions; and
wherein one or more cell voltage monitoring tabs extend from one or more of the fuel cells through one or more of the exposed corner portions.

18. The method of assembling an open cathode fuel cell stack assembly of claim 11 , wherein:
the stack further comprises one or more cell voltage monitoring tabs extending from a corner of one or more of the fuel cells;
each C-shaped clip includes an engagement member configured to engage with one of a pair of opposing edges of the preformed element, and each C-shaped clip is configured to extend along the respective opposing edge of the preformed element while leaving exposed corner portions through which the one or more cell voltage monitoring tabs extend.

Assignees

• Intelligent Energy Ltd

Inventors

• Hood Peter David

Classifications

• H01M8/248 Primary

  Means for compression of the fuel cell stacks · CPC title

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title

• H01M8/006

  Flat · CPC title

• H01M8/02

  Details (electrodes H01M4/86 - H01M4/98) · CPC title

• H01M8/10

  Fuel cells with solid electrolytes · CPC title