WO2004008563A2

WO2004008563A2 - Housing for a fuel cell

Info

Publication number: WO2004008563A2
Application number: PCT/IB2003/002822
Authority: WO
Inventors: Rolf Kurt Papsdorf
Original assignee: Alternate Energy Development Corp Ltd
Priority date: 2002-07-17
Filing date: 2003-07-17
Publication date: 2004-01-22
Also published as: AU2003249117A1; ZA200500523B; WO2004008563A3

Abstract

The invention provides a housing (310) for the cathode and the anode of a zinc/air fuel cell. The housing (310) includes a first housing component (312) which defines a chamber (320) for the anode and an air cathode opening (324) leading into the anode chamber (320). A second housing component (314) is connected to the first housing component (312) so as to extend across the air cathode opening (324) in the first housing component (312), and the air cathode is located between the first and second housing components so as to extend over at least a portion of the air cathode opening (324). The housing (310) also includes a seal (340) which is located around the air cathode opening (324) between the first and second housing components and which forms a hermetic seal between the first and second housing components.

Description

HOUSING FOR A FUEL CELL

BACKGROUND OF THE INVENTION

THIS invention relates to fuel cells. More specifically, the invention relates to an apparatus for housing the cathode and the anode of a zinc/air fuel cell, and to a method for manufacturing such an apparatus.

Methods for securing the air cathode of a zinc/air fuel cell in a housing with an epoxy resin are known. These methods tend to be relatively time- consuming because the epoxy resin has to be very carefully applied to the housing in order to properly seal the air cathode and it is necessary to allow the resin to cure. Furthermore, differences in the coefficients of thermal expansion of the epoxy resin and the housing material can lead to leaks from the air cathode during changes in ambient temperature.

Apart from this, the known housings for zinc/air fuel cells generally include a front mould component and a rear mould component which are connected together with an adhesive and/or screws, making it relatively difficult and time-consuming to replace the anode.

Another drawback associated with the known types of housings for zinc/air fuel cells is that the zinc anode often is embedded in a separate plastic cover which limits the airflow to the anode and hence the effective formation of zinc oxide. It is an object of the present invention to provide an alternative apparatus for housing the anode and the cathode of a zinc/air fuel cell which can be assembled relatively easily and quickly and which allows the zinc anode to be replaced easily and quickly.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a method of manufacturing a housing for a fuel cell comprising the steps of: providing a first housing component which defines a chamber for an anode and an air cathode opening leading into the anode chamber; providing a second housing component which is sized to extend across the air cathode opening in the first housing component; locating a seal and an air cathode between the second housing component and the first housing component; and connecting the second housing component to the first housing component so that the air cathode extends over at least a portion of the air cathode opening and the seal is located around the air cathode opening to form a hermetic seal between the first and second housing components.

The method may include the steps of locating the seal in a recess in the first housing component, locating the air cathode over the air cathode opening and over the seal, and subsequently connecting the second housing component to the first housing component so that the seal is compressed to form a hermetic seal between the first and second housing components.

Alternatively, the method may include the steps of locating the seal in a recess in the second housing component, locating the air cathode over the air cathode opening, and subsequently connecting the second housing component to the first housing component so that the seal is compressed to form a hermetic seal between the first and second housing components.

In one arrangement, the second housing component is connected to the first housing component by means of a friction fit between engaging formations on the first and second housing components.

In another arrangement, the second housing component is connected to the first housing component by means of clipping formations on the first and second housing components.

In yet another embodiment, the first and second housing components are connected together by means of welds, for example sonic welds.

In a preferred arrangement, the method includes the steps of threading a plurality of locating pins on the first housing component through corresponding locating apertures in the seal, the air cathode and the second housing component so as to locate the seal, the air cathode and the second housing component on the housing, and bonding the second housing component to the locating pins on the first housing component, preferably with welds.

Typically, the method includes the step of exposing electrical contacts which are connected to the air cathode.

Ideally, the method includes sealing the anode chamber with a removable closure engageable with the first housing component. The first housing component may be formed from two or more pieces, in which case the pieces may be connected together to form the first housing component by means of a friction fit between engaging formations on the pieces, by means of clipping formations on the pieces, or by means of welds.

In one embodiment of the invention, the first housing component includes a second air cathode opening in an opposite side of the first housing component to the air cathode opening, and the method includes the steps of: providing a third housing component which is sized to extend across the second air cathode opening; locating a second seal and a second air cathode between the third housing component and the first housing component; and connecting the third housing component to the first housing component so that the second air cathode extends over at least a portion of the second air cathode opening and the second seal is located around the second air cathode opening to form a hermetic seal between the first and third housing components.

According to a second aspect of the invention there is provided a housing for a fuel cell comprising: a first housing component which defines a chamber for an anode and an air cathode opening leading into the anode chamber; a second housing component connected to the first housing component so as to extend across the air cathode opening in the first housing component; a seal located around the air cathode opening between the first and second housing components and forming a hermetic seal between the first and second housing components; and an air cathode located between the first and second housing components so as to extend over at least a portion of the air cathode opening.

In a preferred embodiment of the invention, the seal, which typically is formed from an elastomeric material, is located within a recess in the first housing component, and the air cathode is sized to extend over the seal.

Preferably, the second housing component includes means for supporting the air cathode, for example support ribs on an inner face of this component.

The second housing component may be connected to the first housing component by means of a friction fit between engaging formations on the second housing component and corresponding formations on the first housing component.

Alternatively, the second housing component may be connected to the first housing component by means of clipping formations on the second housing component and corresponding formations on the first housing component.

In another embodiment, the second housing component is welded to the first housing component, for example with sonic welds.

Preferably, the first housing component includes a plurality of locating pins which are threaded through corresponding locating apertures in the seal, the air cathode and the second housing component, and the second housing component is bonded to the locating pins on the first housing component, preferably with welds.

The second housing component may include one or more projections for compressing the seal between the first and second housing components.

The first housing component may include support ribs for supporting the anode within the anode chamber.

Preferably, the housing also includes means for exposing electrical contacts which are connected to the air cathode.

Typically, the housing includes a removable closure engageable with the first housing component for sealing the anode chamber.

Ideally, the first housing component or the removable closure includes means for releasing pressure from the anode chamber when the pressure within this chamber rises above a predetermined magnitude relative to ambient pressure.

The first housing component may be formed from two or more pieces that are connected together by means of a friction fit between engaging formations on the pieces, by a clipping connection between the pieces, or by means of welds.

The housing may also include connectors for connecting the housing to adjacent, similar fuel cell housings in series.

In one embodiment of the invention, the first housing component includes a second air cathode opening in an opposite side of the first housing component to the air cathode opening, and the housing further includes: a third housing component connected to the first housing component so as to extend across the second air cathode opening in the first housing component; a second seal located around the second air cathode opening between the first and third housing components and forming a hermetic seal between the first and third housing components; and a second air cathode located between the first and third housing components so as to extend over at least a portion of the second air cathode opening.

The invention also extends to a kit for forming a fuel cell housing of the type described above, the kit including: a first housing component which defines a chamber for an anode and an air cathode opening leading into the anode chamber; a second housing component connectable to the first housing component for holding an air cathode adjacent the air cathode opening; and a seal locatable around the air cathode opening between the first and second housing components to form a hermetic seal between the first and second housing components.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows an exploded perspective view of a fuel cell housing according to a first embodiment of the invention, with certain components omitted for clarity; Figure 2 shows an exploded view, in cross-section, of the housing of

Figure 1 ;

Figure 3 shows a cross-sectional view of a fuel cell housing according to a second embodiment of the invention;

Figure 4 shows a cross-sectional view of a third embodiment of the fuel cell housing according to the present invention;

Figure 5 shows an exploded perspective view of a fourth embodiment of the fuel cell housing according to the invention; and

Figure 6 shows an exploded perspective view of an anode assembly for the housing illustrated in Figure 5.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 of the accompanying drawings illustrates a fuel cell housing according to the present invention. The housing is designated generally with the reference numeral 10 and includes a first housing component 12, which in this embodiment is formed from a support panel 12A and a backing plate 12B, and a second housing component in the form of a front cover 14. The components 12 and 14 are connectable to one another in a manner which is described in detail below.

The support panel 12A defines an air cathode opening 18, and includes six ribs 20 which extend across the opening 18 to provide lateral support for an anode (not shown). A front face 22 of the support panel 12A is seen to include an inner recess 24 which extends around the opening 18 to form a seat for an elastomeric seal (also not shown), and an outer recess 26 which extends around the inner recess 24.

In this embodiment of the invention, the front cover 14 has a peripheral lip 28 which is sized and shaped to form a friction fit within the recess 26 in the support panel 12A, thereby to connect the front cover to the support panel. The front cover 14 also carries a projecting formation or ridge 30 (see Figure 2) which corresponds with the inner recess 24 in the support panel 12A. A series of transverse ribs in the form of a grid 32 extends across the inner surface of the front cover, as shown.

In Figure 1 , the backing plate 12B is seen to include a generally U-shaped projection 34 which extends along a lip 36. The projection 34 is designed to form a friction fit within a corresponding U-shaped groove 38 (see Figure 2) in a rear face 40 of the support panel 12A, thereby to connect the backing plate to the support panel. The backing plate 12B also carries six ribs 42 which correspond with the ribs 20 on the support panel 12A.

In this embodiment of the invention, the housing components 12 and 14 are moulded from a plastics material or a thermoplastics material.

Figure 1 also illustrates a closure 44 which is formed from silicone rubber. The closure 44 includes a tapered neck 46 which is designed to form a press fit in an opening leading into the housing 10, once assembled, and a pair of lugs 48 on a head 50 for facilitating the removal of the closure from the housing.

With reference also to Figure 2 of the drawings, the housing 10 is assembled in the following manner. First, an elastomeric seal 52 is located within the inner recess 24 in the support panel 12A, an air cathode 54 is located over the air cathode opening 18 and the seal 52, and the front cover 14 is connected to the support panel 12A by pressing the lip 28 on the cover 14 into the outer recess 26 in the support panel. As the front cover engages the support panel, the ridge 30 bears against the outer region of the air cathode 54 and compresses the seal 52 to form a hermetic seal between the cover 14 and the support panel 12A around the air cathode opening 18. In this condition of the housing 10, the grid 32 provides lateral support for the air cathode 54 in front of the air cathode opening 18.

Thereafter, the backing plate 12B is connected to the rear face 40 of the support panel 12A by pressing the projection 34 on the backing plate 12B into the groove 38 in the support panel 12A. The backing plate and the support panel together define a chamber for receiving an anode (not illustrated), which when located in the anode chamber is supported by the ribs 42 on the backing plate 12B and the ribs 20 on the support panel 12A.

In practice, once the anode has been inserted into the housing 10, the anode chamber is sealed off with the closure 44. Electrical contacts (not illustrated) connected to the anode and the cathode are fed through formations 56 and 58 in the closure 44 so as to be exposed outside the housing 10, on opposite sides thereof.

Referring back to Figure 1 , the support panel 12A is seen to include vent holes 60 in an upper region thereof. These vent holes are sized to release pressure from the anode chamber when the pressure within this chamber rises above a predetermined magnitude relative to ambient pressure. The support panel also includes connectors 62 for connecting the housing 10, once assembled, to adjacent, similar housings in series.

The fuel cell may then be used to provide power to electrical devices, for example in underground applications or in remote or rural areas.

Figure 3 illustrates another embodiment of the fuel cell housing according to the present invention. In this embodiment, the housing 110 includes a first housing component in the form of a container 112 and a second housing component in the form of a front cover 114. As can be seen, the container 112 includes a front wall 116 and a rear wall 118 which is spaced from the front wall by a chamber 120 for an anode 122. The front wall 116 defines a cathode opening 124 leading into the anode chamber 120, a recess 126 which extends around the cathode opening, and a ridge 128 which extends around the recess 126.

The front cover 114 is similar to the front cover 14 of the housing 10 and carries a peripheral lip 130 which is designed to form a friction fit with the ridge 128 on the front wall 116. The front cover also carries a projecting formation 132 which is arranged to align with the recess 126 in the front wall 116.

In practice, an endless, elastomeric seal (not shown) is positioned within the recess 126, an air cathode (also not shown) is located over the seal so as to cover the air cathode opening 124, and the front cover 114 is fitted to the container 112 in the manner illustrated in Figure 3. It will be appreciated that the projection 132 on the front cover 114 serves to compress the seal in the recess 126, thereby to provide a hermetic seal between the front cover and the container 112 around the air cathode opening 124. Typically, the front cover 114 is then fixed to the container 112 by means of sonic welds along the ridge 128.

The housing 110 also includes a closure 134 for sealing off the anode chamber 120 and allowing electrical contacts connected to the anode and the air cathode to be exposed outside the housing, on opposite sides thereof.

Male connectors 136A and female connectors 136B are provided for connecting adjacent, similar housings to the housing 110 in series.

Although not illustrated, the container 112 or the closure 134 may include vent holes for releasing pressure from the anode chamber 120 when the pressure within this chamber rises above a predetermined magnitude relative to ambient pressure.

Figure 4 illustrates a third embodiment of the fuel cell housing according to the present invention. The housing 210 in this embodiment is similar to the housing 110 in all respects except that the rear wall 212 of the container 214 also includes an air cathode opening 216, and a cover 218 is provided, as shown. As in the case of the housing 110, the container 214 includes a front wall 220 which defines an air cathode opening 222, a recess 224 extending around the air cathode opening 222, and a ridge 226 extending around the recess 224. A front cover 228 carries a peripheral lip 230 and a projection 232 which is arranged to align with the recess 224 in the front wall 220.

The rear wall 212 is seen to be a mirror image of the front wall 220, and accordingly also includes a recess 234 around the air cathode opening 216 and a ridge 236 around the recess 234. Similarly to the front cover 228, the rear cover 218 carries a peripheral lip 238 and a projection 240 which is arranged to align with the recess 234. The housing 210 is assembled by positioning endless, elastomeric seals (not shown) in the recesses 224 and 234, locating air cathodes (also not shown) over the seals so as to cover the air cathode openings 216 and 222, engaging the front cover 228 with the ridge 226 on the front wall 220 of the container 214, and engaging the rear cover 218 with the ridge 236 on the rear wall 212 of the container. Typically, the front and rear covers are welded to the container 214 with sonic welds (not illustrated) along the ridges 226 and 236.

A closure 242 allows the anode chamber 244 to be sealed with electrical contacts connected to the anode 246 and the air cathode (not shown) exposed outside the housing 210, on opposite sides thereof.

As in the case of the previous embodiments, male connectors 248A and female connectors 248B allow the housing 210 to be connected in series to adjacent, similar housings, and the container 214 or the closure 242 may include vent holes (not illustrated) for releasing pressure from the anode chamber 244 when the pressure within this chamber rises above a predetermined magnitude relative to ambient pressure.

Figures 5 and 6 illustrate another embodiment of a fuel cell housing 310 according to the present invention and an anode assembly for the housing. In this embodiment, the housing 310 includes a container 312 and a front cover 314. The container 312 includes a front wall 316 which is spaced from a rear wall 318 by a chamber 320 for an anode 322 (see Figure 6). The front wall 316 defines a cathode opening 324 leading into the chamber 320, as shown. The front wall also defines a grid 326 which together with ribs 328 on the rear wall 318 provides support for the anode 322 within the anode chamber 320. A front face 330 of the front wall 316 includes a recess 332 which extends around the cathode opening 324, and locating pins 336 which project outwardly from the recess 332. Ridges 338 extend around the recess 332, as shown, for receiving the outer cover 314 and allowing electrical contacts (not illustrated) connected to a cathode (also not illustrated) to be exposed on one side of the container 312.

An elastomeric seal 340 is engageable with the recess 332 and includes locating apertures 342 corresponding to the locating pins 336.

The front cover 314 also includes locating apertures 344 corresponding to the locating pins 336 on the front wall 316 of the container 312. In this embodiment of the invention, the front cover 314 defines a grid structure 346 for supporting a cathode (not illustrated) adjacent the cathode opening 324.

The housing 310 is assembled by threading the locating pins 336 through the locating apertures 342 in the seal 340 so as to locate the seal on the front wall 316 of the container 312, threading the locating pins 336 through corresponding locating apertures in an air cathode (not shown) so as to locate the cathode over the cathode opening 324, threading the locating pins 336 through the locating apertures 344 in the front cover 314 so as to locate the front cover over the cathode, applying pressure to the front cover 314 so as to form a hermetic seal between the front cover and the front wall 316 of the container 312, and bonding the locating pins 336 to the front cover 314, in this case with welds. Typically, a sheet (not shown) which is gas impermeable is located between the air cathode and the front cover'314, and the seal 340 and the front cover 314 include formations, such as grooves and/or ribs, for enhancing the seal formed between the front cover and the front wall 316 of the container 312. The electrical contacts connected to the air cathode are fed along grooves 348, threaded between the front face 330 and cross bars 350, and folded back over the cross bars 350 to provide exposed electrical connections on the fuel cell housing 310.

Thereafter, the anode 322 is placed in a gas permeable, polypropylene nonwoven bag 352 and the bag and anode are located in the anode chamber 320 so that electrical contacts 354 connected to the anode 322 locate in recesses 356 and hang over the rear wall 318 to present exposed electrical connections on the fuel cell housing 310. The bag 352 prevents zinc oxide generated by the anode 322, in use, from contacting the air cathode, and also prevents contamination of potassium hydroxide within the housing 310, without adversely affecting air flow from the air cathode to the anode.

A closure 356 allows the anode chamber 320 to be sealed, in use, and includes vent holes 358 for releasing pressure from the anode chamber 320 when the pressure within this chamber rises above a predetermined magnitude relative to ambient pressure.

As in the case of the previous embodiments, the housing 310 includes male connectors 360A and female connectors 360B which allow the housing 310 to be connected in series to adjacent, similar housings.

It will be appreciated that, with suitable modifications, the housing 310 could include a second cathode opening in the rear wall 318 thereof and a rear cover so as to accommodate two air cathodes in a manner similar to the Figure 4 embodiment of the invention.

One advantage of the fuel cell housing according to the embodiments described above is that it allows a user to replace the anode relatively easily and quickly by simply removing the closure, withdrawing the anode from the anode chamber, inserting a new anode into the anode chamber and replacing the closure. Another advantage of the housing according to the present invention is that it is relatively easy, fast and cost effective to manufacture. Furthermore, the front and/or rear covers are mechanically sealed to the housing so as to ensure that the air cathode is properly sealed within the housing. Finally, since the anode is not contained within a separate plastic cover which impedes air flow from the air cathode, the housing allows for the effective formation of zinc oxide at the anode.

Claims

A method of manufacturing a housing for a fuel cell comprising the steps of: providing a first housing component which defines a chamber for an anode and an air cathode opening leading into the anode chamber; providing a second housing component which is sized to extend across the air cathode opening in the first housing component; locating a seal and an air cathode between the second housing component and the first housing component; and connecting the second housing component to the first housing component so that the air cathode extends over at least a portion of the air cathode opening and the seal is located around the air cathode opening to form a hermetic seal between the first and second housing components.

A method according to claim 1, including the steps of locating the seal in a recess in the first housing component, locating the air cathode over the air cathode opening and over the seal, and subsequently connecting the second housing component to the first housing component so that the seal is compressed to form a hermetic seal between the first and second housing components.

A method according to claim 1 , including the steps of locating the seal in a recess in the second housing component, locating the air cathode over the air cathode opening, and subsequently connecting the second housing component to the first housing component so that the seal is compressed to form a hermetic seal between the first and second housing components.

4. A method according to any one of claims 1 to 3, wherein the second housing component is connected to the first housing component by means of a friction fit between engaging formations on the first and second housing components.

5. A method according to any one of claims 1 to 3, wherein the second housing component is connected to the first housing component by means of clipping formations on the first and second housing components.

6. A method according to any one of claims 1 to 3, wherein the first and second housing components are connected together by means of welds.

7. A method according to claim 6, wherein the welds are sonic welds.

8. A method according to any one of claims 1 to 3, wherein the first and second housing components are connected together by threading a plurality of locating pins on the first housing component through corresponding locating apertures in the seal, the air cathode and the second housing component so as to locate the seal, the air cathode and the second housing component on the first housing component, and bonding the second housing component to the locating pins on the first housing component.

9. A method according to claim 8, wherein the second housing component is bonded to the locating pins on the first housing component with welds.

10. A method according to any one of the preceding claims, including the step of exposing electrical contacts connected to the cathode outside the housing.

11. A method according to any one of the preceding claims, including the step of sealing the anode chamber with a removable closure engageable with the first housing component.

12. A method according to any one of the preceding claims, wherein the first housing component is formed from two or more pieces.

13. A method according to claim 12, wherein the pieces of the first housing component are connected together by means of a friction fit between engaging formations on the pieces, by means of clipping formations on the pieces, or by means of welds.

14. A method according to any one of the preceding claims, wherein the first housing component includes a second air cathode opening in an opposite side of the first housing component to the air cathode opening, and the method includes the steps of: providing a third housing component which is sized to extend across the second air cathode opening; locating a second seal and a second air cathode between the third housing component and the first housing component; and connecting the third housing component to the first housing component so that the second air cathode extends over at least a portion of the second air cathode opening and the second seal is located around the second air cathode opening to form a hermetic seal between the first and third housing components.

15. A housing for a fuel cell comprising: a first housing component which defines a chamber for an anode and an air cathode opening leading into the anode chamber; a second housing component connected to the first housing component so as to extend across the air cathode opening in the first housing component; a seal located around the air cathode opening between the first and second housing components and forming a hermetic seal between the first and second housing components; and an air cathode located between the first and second housing components so as to extend over at least a portion of the air cathode opening.

16. A housing according to claim 15, wherein the seal is located within a recess in the first housing component, and the air cathode is sized to extend over the seal.

17. A housing according to claim 16, wherein the seal is formed from an elastomeric material.

18. A housing according to any one of claims 15 to 17, wherein the second housing component includes means for supporting the air cathode.

19. A housing according to claim 18, wherein the means for supporting the air cathode comprises support ribs on an inner face of the second housing component.

20. A housing according to any one of claims 15 to 19, wherein the second housing component is connected to the first housing component by means of a friction fit between engaging formations on the second housing component and corresponding formations on the first housing component.

21. A housing according to any one of claims 15 to 19, wherein the second housing component is connected to the first housing component by means of clipping formations on the second housing component and corresponding formations on the first housing component.

22. A housing according to any one of claims 15 to 19, wherein the second housing component is welded to the first housing component.

23. A housing according to any one of claims 15 to 19, wherein the first housing component includes a plurality of locating pins which are threaded through corresponding locating apertures in the seal, the air cathode and the second housing component, and the second housing component is bonded to the locating pins on the first housing component.

24. A housing according to claim 23, wherein the second housing component is bonded to the locating pins on the first housing component with welds.

25. A housing according to any one of claims 15 to 24, wherein the second housing component includes one or more projections for compressing the seal between the first and second housing components.

26. A housing according to any one of claims 15 to 25, wherein the first housing component includes support ribs for supporting the anode within the anode chamber.

27. A housing according to any one of claims 15 to 26, including means for exposing electrical contacts connected to the cathode outside the housing.

28. A housing according to any one of claims 15 to 27, including a removable closure engageable with the first housing component for sealing the anode chamber.

29. A housing according to claim 28, wherein the first housing component or the removable closure includes means for releasing pressure from the anode chamber when the pressure within this chamber rises above a predetermined magnitude relative to ambient pressure.

30. A housing according to any one of claims 15 to 29, wherein the first housing component is formed from two or more pieces that are connected together by means of a friction fit between engaging formations on the pieces, by a clipping connection between the pieces, or by means of welds.

31. A housing according to any one of claims 15 to 30, including connectors for connecting the housing to adjacent, similar fuel cell housings in series.

32. A housing according to any one of claims 15 to 31 , wherein the first housing component includes a second air cathode opening in an opposite side of the first housing component to the air cathode opening, and the housing further includes: a third housing component connected to the first housing component so as to extend across the second air cathode opening in the first housing component; a second seal located around the second air cathode opening between the first and third housing components and forming a hermetic seal between the first and third housing components; and a second air cathode located between the first and third housing components so as to extend over at least a portion of the second air cathode opening.

33. A kit for forming a fuel cell housing according to any one of claims 15 to 32, the kit including: a first housing component which defines a chamber for an anode and an air cathode opening leading into the anode chamber; a second housing component connectable to the first housing component for holding an air cathode adjacent the air cathode opening; and a seal locatable around the air cathode opening between the first and second housing components to form a hermetic seal between the first and second housing components.