Title: Electrochemical cell
Abstract: The invention is an electrochemical cell for the separation of hydrogen and oxygen from water made of a fuel plenum with a fuel inlet, a oxidant plenum, a porous substrate, an undulating channel with walls, a support member between the walls, an anode and a cathode in the walls, an electrolyte contacting the anode and the cathode forming a barrier preventing transfer of fuel and oxidant to the cathode or to the anode, a two separate coatings on the porous substrate to prevent fuel or oxidant from entering the porous substrate, a sealant barrier to divide the two plenums, and a negative electrical and a positive electrical connection on the side of the porous substrate for flowing current from an outside source to the porous substrate.
Patent Number: 6,872,287 Issued on 03/29/2005 to McLean
| Inventors:
|
McLean; Gerard Francis (West Vancouver, CA)
|
| Assignee:
|
Angstrom Power (CA)
|
| Appl. No.:
|
349338 |
| Filed:
|
January 22, 2003 |
| Current U.S. Class: |
204/265; 204/266; 204/295; 204/296; 429/36; 429/38 |
| Intern'l Class: |
C25B 009//00; C25C 007//00; H01M 002//08; H01M 002//14 |
| Field of Search: |
204/263,265,266,295,296
429/36,38
|
References Cited [Referenced By]
U.S. Patent Documents
| 5316643 | May., 1994 | Ahn et al. | 204/265.
|
| 5631099 | May., 1997 | Hockaday | 429/30.
|
| 5759712 | Jun., 1998 | Hockaday | 429/30.
|
| 5861221 | Jan., 1999 | Ledjeff | 429/32.
|
| 5925477 | Jul., 1999 | Ledjeff | 429/32.
|
| 6024848 | Feb., 2000 | Dufner et al. | 204/252.
|
| 6060188 | May., 2000 | Muthuswamy | 429/31.
|
| 6127058 | Oct., 2000 | Pratt | 429/30.
|
| 6312846 | Nov., 2001 | Marsh | 429/30.
|
| Foreign Patent Documents |
| 2339058 | Jan., 2000 | GB | .
|
| 8050903 | Feb., 1996 | JP.
| |
| WO 01/95406 | Dec., 2001 | WO.
| |
Primary Examiner: Valentine; Donald R.
Attorney, Agent or Firm: Buskop Law Group, P.C., Buskop; Wendy
Parent Case Text
The application herein claims priority from the provisional Patent
Application 60/354,637 with a filing date of Feb. 6, 2002.
Claims
What is claimed is:
1. An electrochemical cell for the separation of hydrogen and oxygen from
water comprising:
a. a first plenum containing a fuel inlet for filling said first plenum
with fuel;
b. a second plenum containing oxidant;
c. a porous substrate communicating with said first plenum, and said second
plenum further comprising a top, a bottom, a first side and a second side;
d. an undulating channel formed in said porous substrate having a first
channel wall and a second channel wall;
e. a support member disposed between said first channel wall and said
second channel wall;
f. an anode formed from a first catalyst layer disposed on said first
channel wall;
g. a cathode formed from a second catalyst layer disposed on said second
channel wall;
h. electrolyte disposed in said undulating channel contacting the anode and
the cathode forming a barrier preventing transfer of fuel to the cathode
and preventing transfer of oxidant to the anode;
i. a first coating disposed on at least a portion of said porous substrate
to prevent fuel from entering said porous substrate;
j. a second coating disposed on at least a portion of said porous substrate
for preventing oxidant from entering said porous substrate;
k. wherein said first plenum and said second plenum are separated by the
porous substrate and the electrolyte, such that fuel and oxidant are
blocked from said anode and said cathode by the electrolyte;
l. a sealant barrier disposed on said porous substrate between said first
plenum and said second plenum opposite said anode and said cathode; and
m. a negative electrical connection disposed on said second side of said
porous substrate for flowing current from said electrochemical cell to an
outside source and a positive electrical connection disposed on said first
side of said porous substrate for flowing current from said outside source
to said porous substrate.
2. The electrochemical cell of claim 1, wherein said porous substrate is
formed in the shape of a cylinder and said undulating channel is disposed
parallel to the axis of said formed cylinder.
3. The electrochemical cell of claim 2, wherein the separation ability of
the electrochemical cell is increased by adding a plurality of undulating
channels in parallel relation to each other around the circumference of
said formed cylinder.
4. The electrochemical cell of claim 1, wherein said porous substrate is
formed in the shape of a cylinder and said undulating channel is disposed
radially around said axis of said formed cylinder.
5. The electrochemical cell of claim 4, further having a plurality of
undulating channels in parallel relationship to each other.
6. The electrochemical cell of claim 1, wherein said porous substrate is
formed in the shape of a cylinder and said undulating channel is disposed
in a spiral configuration around the circumference of said formed
cylinder.
7. The electrochemical cell of claim 1, wherein said porous substrate is a
conductive material.
8. The electrochemical cell of claim 1, wherein said porous substrate
comprises a member of the group consisting of a metal foam, graphite,
graphite composite, silicon wafer, sintered polytetrafluoro ethylene,
pellets of polymer, reinforced phenolic resin, recycled organic material
and combinations thereof.
9. The electrochemical cell of claim 1, wherein said support member is an
insulating material.
10. The electrochemical cell of claim 9, wherein said insulating material
comprises a member of the group consisting of silicon, graphite composite,
polytetra fluoroethylene, polymethamethacrylate, polymers, copolymers,
cross-linked polymers, wood, and combinations thereof.
11. The electrochemical cell of claim 1, further comprising a first plenum
outlet.
12. The electrochemical cell of claim 1, further comprising a second plenum
inlet.
13. The electrochemical cell of claim 1, further comprising a second plenum
outlet.
14. The electrochemical cell of claim 1, wherein said first plenum
comprises a hydrogen gas.
15. The electrochemical cell of claim 14, wherein said hydrogen gas is at
least 90% hydrogen.
16. The electrochemical cell of claim 1, wherein said first plenum
comprises a permeable material.
17. The electrochemical cell of claim 1, wherein said first plenum further
comprises an outlet.
18. The electrochemical cell of claim 1, wherein said anode is embedded in
said first channel wall.
19. The electrochemical cell of claim 1, wherein said cathode is embedded
in said second channel wall.
20. The electrochemical cell of claim 1, wherein said electrolyte is a
member of the group consisting of a perfluoronated polymer containing
sulphonic groups, an aqueous acidic solution having a ph of at least 7,
and an aqueous alkaline solution having a ph of at most 4.
21. The electrochemical cell of claim 1, wherein said first coating and
said second coating are the same material.
22. The electrochemical cell of claim 1, wherein said first coating and
said second coating are different material.
23. The electrochemical cell of claim 1, wherein said first and second
coating can comprise a member of the group consisting of polymer coating
poly tetrafluoro ethylene, polymethyl methacrylate, polyethylene,
polypropylene, polybutylene, and copolymer thereof, cross-linked polymers
thereof, conductive metal.
24. The electrochemical cell of claim 1, wherein said first catalyst layer
and said second catalyst layers are members of the group consisting of
noble metals, alloys comprising noble metals, platinum, platinum alloys,
ruthenium, alloys of ruthenium, and combinations thereof.
25. The electrochemical cell of claim 24, wherein said first and second
catalyst layers are ternary alloys comprising at least one noble metal.
26. The electrochemical cell of claim 24, wherein said first and second
catalyst layers are a ruthenium--ruthenium alloy.
27. The electrochemical cell of claim 24, wherein said first catalyst layer
and second catalyst layer each has catalyst loading quantity wherein the
amount of catalyst is different for each layer.
28. The electrochemical cell of claim 1, wherein said undulating channel is
in at least two planes.
29. The electrochemical cell of claim 1 wherein said undulating channel has
dimension of a height ranging from 1 microns to 10 cm, a width ranging
from 1 nanometer to 1 mm, and a length ranging from 1 nanometer to 100
meters.
30. The electrochemical cell of claim 1, having between 1 undulating
channel and 5000 undulating channels.
31. The electrochemical cell of claim 30, having 75 undulating channels.
32. The electrochemical cell of claim 1, wherein said first plenum has a
rectangular cross section.
33. The electrochemical cell of claim 1, wherein said first plenum has an
annular cross section.
34. The electrochemical cell of claim 1, wherein said porous substrate
communicating with said first plenum further comprises a horizontal axis,
and said electrolyte disposed in said channel is oriented at an angle
perpendicular to said horizontal axis.
Description
FIELD OF THE INVENTION
The present invention relates to a method for making fuel cells. More
specifically a method for making a fuel cell layer comprising multiple
cells using distinct channels formed in a single porous substrate.
BACKGROUND OF THE INVENTION
Existing fuel cells generally are a stacked assembly of individual fuel
cells, with each stack producing high current at low voltage. The typical
cell construction involves reactant distribution and current collection
devices brought into contact with a layered electrochemical assembly
consisting of a gas diffusion layer, a first catalyst layer, an
electrolyte layer, a second catalyst layer and a second gas diffusion
layer. With the exception of high temperature fuel cells, such as molten
carbonate cells, most proton exchange membrane, direct methanol, solid
oxide or alkaline fuel cells have a layered planar structure where the
layers are first formed as distinct components and then assembled into a
functional fuel cell stack by placing the layers in contact with each
other.
One major problem with the layered planar structure fuel cell has been that
the layers must be held in intimate electrical contact with each other,
which if intimate contact does not occur the internal resistance of the
stack increases, which decreases the overall efficiency of the fuel cell.
A second problem with the layered planar structured fuel cell has been that
with larger surface areas, problems occur to maintain consistent contact
with both cooling and water removal in the inner recesses of the layered
planar structured fuel cell. Also if the overall area of the cell becomes
too large then there are difficulties creating the contacting forces
needed to maintain the correct fluid flow distribution of reactant gases
over the electrolyte surface.
Existing devices also have the feature that with the layered planar
structure fuel cell since both fuel and oxidant are required to flow
within the plane of the layered planar structured fuel cell, at least 4
and up to 6 distinct layers have been required to form a workable cell,
typically a first flowfield, a first gas diffusion layer, a first catalyst
layer, a first electrolyte layer, a second catalyst layer, a second gas
diffusion layer, a second flowfield layer and a separator. These layers
are usually manufactured into two separate fuel cell components and then a
fuel cell stack is formed by bringing layers into contact with each other.
When contacting the layers care must be taken to allow gas diffusion
within the layers while preventing gas leaking from the assembled fuel
cell stack. Furthermore, all electrical current produced by the fuel cells
in the stack must pass through each layer in the stack, relying on the
simple contacting of distinct layers to provide an electrically conductive
path. As a result, both sealing and conductivity require the assembled
stack to be clamped together with significant force in order to activate
perimeter seals and reduce internal contact resistance.
A need has existed for a micro, or small fuel cell having high volumetric
power density.
A need has existed for a micro fuel cell capable of low cost manufacturing
because of having fewer parts than the layered planar structure fuel cell.
A need has existed for a micro fuel cell having the ability to utilize a
wide variety of electrolytes.
A need has existed for a micro fuel cell, which has substantially reduced
contact resistance within the fuel cell.
A need has existed to develop fuel cell topologies or fuel cell
architectures that allow increased active areas to be included in the same
volume, i.e. higher density of active areas. This will allow fuel cells to
be optimized in a manner different than being pursued by most fuel cell
developers today.
SUMMARY OF THE INVENTION
The present invention contemplates an electrochemical cell for the
separation of hydrogen and oxygen from water. The electrochemical cell has
a fuel plenum with a fuel inlet, a oxidant plenum, a porous substrate, an
undulating channel with walls, a support member between the walls, an
anode and a cathode in the walls, an electrolyte contacting the anode and
the cathode forming a barrier preventing transfer of fuel and oxidant to
the cathode or to the anode. The invention also has two separate coatings
on the porous substrate to prevent fuel or oxidant from entering the
porous substrate, a sealant barrier to divide the two plenums, and a
negative electrical and a positive electrical connection on the side of
the porous substrate for flowing current from an outside source to the
porous substrate.
BRIEF DESCRIPTION OF THE FIGURES
A specific embodiment of the invention will be described by way of example
with reference to the accompanying drawings, in which:
FIG. 1 is a cross-sectional view of a first embodiment of the inventive
fuel cell;
FIG. 2 is a cross-sectional view of a dead ended embodiment of the
inventive fuel cell;
FIG. 3 is a cross-sectional view of another embodiment of a dead ended fuel
cell;
FIG. 4 is a cross-sectional view of a fuel cell layer formed by combining
multiple fuel cells of the type described in FIG. 1;
FIG. 5 is a cross-sectional view of a fuel cell with multiple fuel cells
formed within a single substrate;
FIG. 6 is a perspective view of a fuel cell layer containing multiple fuel
cells;
FIG. 7 is another detailed perspective fuel of the fuel cell of the
invention with undulated, irregular channel;
FIG. 8 is a perspective view of a cylindrical version of the fuel cell of
FIG. 1;
FIG. 9 is a cross-sectional view of the embodiment of the fuel cell of FIG.
8;
FIG. 10 is another embodiment of the inventive fuel cell of FIG. 8 with the
channels in the form of a set of stacked annular rings;
FIG. 11 is another embodiment of the inventive fuel cell of FIG. 8 with the
channels in the form of a spiral around the cylinder; and
FIG. 12 is another embodiment of a fuel cell sandwich with a plurality of
fuel cell layers.
DETAILED DESCRIPTION OF INVENTION
The present invention relates to a microstructure fuel cell having a single
substrate, which is preferably porous, an assembly of fuel cells having a
multiple substrate structure, and a system, which includes the novel fuel
cell design and the mounting of an electronic device, such as a cellular
phone, or possibly a flashlight on said fuel cell for operation.
The invention relates to a specific fuel cell architecture that is of an
integrated design in which the functions of gas diffusion layers, catalyst
layers, and electrolyte layers are integrated into a single substrate.
This architecture makes it possible to fold together the various `layers`
of which a working fuel cell is formed and produce linear, curvilinear,
undulating or even fractal shaped electrolyte paths that allow for higher
volumetric power density to be achieved. In addition, by forming the
various fuel cell layers within a single substrate the problem of simple
contacting of fuel cell components to create electrical connections is
eliminated, thus creating the potential for lower internal cell
resistances to be achieved.
Unlike existing fuel cell designs, the present invention, in one
embodiment, provides convoluted electrolyte layers, which do not smoothly
undulate. Other embodiments of the invention include shapes which are
essentially non-smooth. Utilizing such non-smooth electrolyte paths allows
for greater overall surface areas for the fuel cell reactions to be packed
into a given volume than can be achieved when planar electrolyte layers
are employed as in conventional fuel cell designs.
The present invention contemplates the use of a design which was inspired
by fractal designs, which provides long electrolyte path lengths. The
invention includes a method for building fuel cells and "stacks" that are
not dependent on the layered process and which do not require the
post-manufacturing assembly of distinct layered components. The invention
also contemplates a design which has the fuel cell layers turned on their
side relative to the overall footprint of the assembled fuel cell device.
The invention contemplates building multiple fuel cells with an integrated
structure on a single substrate using parallel manufacturing methods.
Specifically, it is contemplated to use a porous substrate for the fuel
cell through which reactant gas will diffuse with little driving force.
The substrate may or may not be electrically conductive. If it is
conductive, it is contemplated to insulate at least a portion of the
substrate, which typically would separate the anode from the cathode, this
insulation may be formed by the electrolyte separating anode from cathode
and if necessary an insulating structural member may be added. More
specifically, the fuel cell is contemplated to have: (a) a fuel plenum
containing fuel molecules and a fuel plenum inlet for filling the fuel
plenum with fuel molecules; (b) an oxidant plenum containing oxygen
molecules; (c) a porous substrate communicating with the fuel plenum, and
the oxidant plenum further comprises a top, a bottom, a first side and a
second side; (d) an undulating channel formed in the porous substrate
having a first channel wall, a second channel wall; (e) a support member
disposed between the first channel wall and the second channel wall; (f)
an anode formed from a first catalyst layer disposed on the first channel
wall; (g) a cathode formed from a second catalyst layer disposed on the
second channel wall; (h) electrolyte disposed in the undulating channel
contacting the anode and the cathode forming a barrier preventing transfer
of fuel molecules to the anode or cathode and preventing transfer of
oxygen molecules to the anode or cathode; (i) a first coating disposed on
at least a portion of the porous substrate to prevent fuel molecules from
entering the porous substrate; (j) a second coating disposed on at least a
portion of the porous substrate for preventing oxygen molecules from
entering the porous substrate; (k) wherein the fuel plenum and the oxidant
plenum are separated by the porous substrate and the electrolyte, such
that fuel molecules are blocked from the cathodes and oxygen molecules are
blocked from the anode by the electrolyte; (l) a sealant barrier disposed
on the porous substrate between the fuel plenum and the oxidant plenum
opposite the anode and the cathode; (m) a negative electrical connection
disposed on the second side of the porous substrate for flowing current
from the fuel cell to an outside source and a positive electrical
connection disposed on the first side of the porous substrate for flowing
current from the outside source to the porous substrate.
Referring to FIG. 1, which is a cross-sectional view of one embodiment of
the invention, fuel cell 8 has a fuel plenum 10 containing fuel molecules
11. A porous substrate 12 is adjacent the fuel plenum 10. The fuel plenum
can have a fuel plenum inlet 18. The fuel plenum can also have a fuel
plenum outlet 20. An oxidant plenum 16 containing oxygen molecules 13 is
adjacent the porous substrate 12.
The porous substrate 12 has an undulating channel 14. The undulating
channel 14 has a first channel wall 22 and a second channel wall 24. A
support member 26 separates first channel wall 22 from second channel wall
24. Additionally the porous substrate 12 has a top 100, bottom, 102, first
side, 104 and a second side 106.
An anode 28 is created on the surface of the first channel wall 22,
although the anode could be embedded in the wall as well. Anode 28 is
created using a first catalyst layer 38 on the surface of the first
channel wall 22.
A cathode 30 is formed on the surface of the second channel wall 24. Like
the anode 28, the cathode 30 could be embedded in the second channel wall
24. Cathode 30 is created using a second catalyst layer 40.
An electrolyte 32 is disposed in the undulating channel 14.
A first coating 34 is disposed on a portion of the porous substrate 12
providing a layer between the porous substrate 12 and the fuel plenum 10.
A second coating 36 is disposed on the porous substrate 12 providing a
layer between the porous substrate and the oxidant plenum 16.
A sealant barrier 44 can either be directly disposed on the porous coating
or formed in a sealant barrier channel 43 on the porous substrate 12. An
optional second sealant barrier 46 can be used in some of the fuel cell
designs.
A negative electrical connection 48 is engaged with the porous substrate 12
on the anode side of the porous substrate 12.
A positive electrical connection 50 is engaged with the porous substrate 12
on the cathode side of the porous substrate 12.
The oxidant plenum 16 can have an oxidant plenum inlet 52 and an oxidant
plenum outlet 54.
FIG. 2 is another embodiment of the invention showing a dead ended version
of the fuel cell specifically excluding the fuel outlet 20 and the oxidant
outlet 54 of the FIG. 1 embodiment.
FIG. 3 is a cross section of another dead ended version of the fuel cell
which excludes the fuel inlet 18 and oxidant inlet 52 of the embodiment of
FIG. 1.
FIGS. 4 and 5 are cross-section views of the fuel cell of FIG. 1 showing an
association of multiple fuel cells on one substrate to form a fuel cell
layer.
FIG. 4 shows fuel cell 8 is formed from a substrate 12 which is made
adjacent a second fuel cell 114 formed from a second substrate 62. The
first and second fuel cells may be formed from either the association of
multiple substrates or, as shown in FIG. 5, the first and second fuel
cells may be formed by creating multiple channels within a single
substrate.
For these two embodiments, it is best to review them in comparison to each
other. In FIG. 4, the two fuel cell structures are formed adjacent each
other by creating a sealant barrier 44 between the substrates 12 and 62.
In FIG. 5, the same fuel cell structures are formed in a single substrate
12 with the sealant barrier formed in the sealant barrier channel 43. In
both cases, sealant barrier 44 shown in both FIGS. 4 and 5, provide an
electrically conductive, and gas impermeable connection between the two
fuel cells.
This association of two fuel cells, either by the structure of FIG. 4 or
the structure of FIG. 5, can be extended to place an arbitrary number of
fuel cells in association with each other having the effect of producing a
series electrical configuration. In both embodiments, the ends of the
multiple structures are sealed with a sealant barrier 44 and a second
sealant barrier 46. In both embodiments, negative electrical connection 48
is attached on one end of the multiple fuel cell assembly and positive
electrical connection 50 is attached on the other end of the multiple fuel
cell assembly to allow the multiple fuel cell assembly to drive an
external electrical load.
The association of multiple fuel cells produces a fuel cell layer 64 having
a fuel side 116 which is brought into association with a fuel plenum 10
and an oxidant side 118 which is brought into association with an oxidant
plenum 16.
If the substrate material from which the fuel cells within the fuel cell
layer is formed, then electrical current produced by the individual fuel
cells is able to flow directly through the substrate material to create a
bipolar fuel cell stack within the formed fuel cell layer. If the
substrate material from which the fuel cells within the fuel cell layer is
formed is not electrically conductive then the first coating 34 and second
coating 36 should both be made of an electrically conducting material and
formed so that first coating 34 is in electrical contact with the anode 40
while second coating 36 is in electrical contact with cathode 38. The
first coating 34 is also made in electrical contact with the positive
electrical connector 50 and the second coating 36 is made in electrical
contact with the negative electrical connector 48. In either case, with a
conductive or non-conductive substrate the electrical current produced by
the fuel cell is able to be transported to the positive and negative
electrical connections.
When multiple fuel cells are formed into a fuel cell layer, as described in
FIGS. 4 and 5 a series electrical connection of the individual fuel cells
results. The sealant barrier 44 is made of a conductive material. When the
substrate material is conductive, a series connection of the individual
fuel cells results, with the summed voltages of the multiple fuel cells
producing a potential difference between the positive and negative
electrical connections at either end of the fuel cell layer. When
non-conductive substrates are used the first and second coatings,
previously described, are made to be in electrical contact with each other
by connecting the top and bottom of the conductive sealant barrier 44. In
either case, with conductive or non-conductive substrate material, a
series electrical connection of each of the fuel cells in the fuel cell
layer is achieved without the need to clamp distinct components together.
Also, the direction of current flow in the fuel cell layer is overall in
the plane of the fuel cell layer rather than being orthogonal to the fuel
cell layer as is the case in most current designs.
FIG. 6 is a perspective view of a fuel cell layer. In this Figure, a
channel 14 is formed in a porous substrate 12 as per the description of
FIG. 1. Sealant barriers 44 separate the undulating channel 14 and a
second undulating channel 58. The structure is repeated to seal against a
third undulating channel 60. Fuel cell layers manufactured using this
invention can continue the structure with sealant barrier to form as many
fuel cells as desired within a single layer. The determination of the
spacing between individual fuel cells within the fuel cell layer is at the
discretion of the designer, limited by pragmatic issues of
manufacturability and mass transport issues within the porous substrate.
The overall structure of the fuel cell layer 64 creates a series connection
of the individual fuel cells 8. Positive electrical connection 50 and
negative electrical connection 48 allow an external load to be connected
to the fuel cell layer, which produces a voltage which is a multiple of
the single cell voltage to be produced within the fuel cell layer.
FIG. 7 shows a similar view of the fuel cell layer 64 but in this Figure,
having a channel with a less straight structure. FIG. 7 is essentially the
same structure as shown in FIG. 1, but repeated multiple times creating a
multi-cell structure.
FIG. 8 is a perspective view of a cylindrical version or formed cylinder 56
of the fuel cell of FIG. 1. In this FIG. 8, the fuel plenum 10 is interior
to the porous substrate 12, and the overall fuel cell 8 is in the shape of
a cylinder. In this embodiment, the porous substrate has an undulating
channel 14, and a second undulating channel 58 and a third undulating
channel 60.
FIG. 9 is a cross section of the cylindrical version of the fuel cell of
FIG. 8. In this cross section, the porous substrate 12 can have a first
coating 34 with an undulating channel 14 and a first channel wall 22 and a
second channel wall 24. The anode 28 is shown formed from the first
catalyst layer 38. The support member 26 separates the first channel wall
22 from the second channel wall 24. The cathode 30 is made from a second
catalyst layer 40. The fuel plenum 10 with fuel molecules 11 is shown on
the interior side of the formed cylinder 56. The negative electrical
connector 48 is shown adjacent sealant barrier 44. The positive electrical
connector 50 is shown adjacent sealant barrier 44. A second coating 36 is
shown disposed on the porous substrate 12, on the outside of the cylinder.
FIG. 10 is another embodiment of the formed cylinder 56 having undulating
channel 14 disposed radially and orthogonal to the axis of the cylinder
56.
FIG. 11 is another embodiment of the formed cylinder 56 having undulating
channel 14 disposed in a wound or spiral fashion around the perimeter of
the cylinder 56.
FIG. 12 is a cutaway perspective view of an embodiment of a fuel cell
sandwich with two fuel cell layers, a first fuel cell layer 64 and a
second fuel cell layer 112 organized so that the hydrogen side 116 of the
two fuel cell layers are facing each other.
In this Figure, the two fuel cell layers are sealed with seal 130 so that
the fuel plenum 11) is formed by the two fuel cell layers and the
perimeter seal. The two positive electrical connectors are connected to
positive connector 120 and the two negative electrical connectors are
connected to negative connector 122 so that the two layered fuel cell
assemblies are now connected in an electrically parallel configuration.
The resulting assembly is fuel cell sandwich 66 having a sandwich top 70
and a sandwich bottom 72, the sandwich top and sandwich bottom are the
oxidant sides of the respective fuel cell layers. The resulting assembly
is an enclosed plenum air breathing fuel cell that achieves a series of
electrical connections of the individual fuel cells in each fuel cell
layer and a parallel electrical connection of the two fuel cell layers.
Only fuel is required to be fed to the interior of the sandwich structure
and electrical current flows within the two fuel cell layers independently
of one another. There is no electrical connection between the two fuel
cell layers except at the parallel connection of the positive and negative
electrical connections at either end of the fuel cell layers in the
sandwich.
In yet another embodiment, the porous substrate can be utilized in a one
plane, and have a rectangular, square or orthogonal shape, or
alternatively, it can be undulating and irregularly shaped. The channels
formed in the porous substrate can be of arbitrary shape. A preferred
embodiment includes a plurality of thin channels that run parallel to each
other and follow an irregular path that folds back on itself in a manner
suggestive of a fractal pattern. A preferred embodiment contemplates that
the substrate is formed in the shape of a cylinder and the undulating
channel is utilized in the center of the cylinder, along the longitudinal
axis of the cylinder, such that the undulating channel is generally
parallel to the axis of the cylinder. More than one undulating channel can
be used with the substrate. The voltage of the resulting fuel cell can be
increased by using more undulating channels. These channels can be created
in parallel relationship with each other and can be placed in the center
of the cylinder, in the center of the substrate, if the substrate has
another geographical shape, or placed around the circumference of
substrate, such as the circumference of the cylinder. Alternatively, the
undulating channels may be formed so that they are radially disposed
around the axis of the substrate or cylinder. In yet another embodiment,
the undulating channels can be formed so that they are in a spiral
configuration around the circumference of the substrate.
Although various materials could be used for the porous substrate, one
usable material could be a conductive material. Materials such as metal
foams, graphites, graphite composites, one ore more silicon wafers,
sintered polytetrafluoro ethylene, pellets of polymer, reinforced phenolic
resins, recycled organic material, such as smashed up bit of coconut and
various combinations of these materials are contemplated as usable in this
invention.
The undulating channel is contemplated to have at least one, but
potentially, up to 50 support members separating the walls of the
undulating channel. The support members can be located at the extreme ends
of the channel, such as forming a top or bottom, or can be located in the
middle portion of the channel, or be oriented at an angle to the center of
the undulating channel. It is contemplated that the support member can be
an insulating material. If an insulating material is used, it is
contemplated that silicon, graphite composite, polytetra fluoroethylene,
polymethamethacrylate, polymers, copolymers, cross-linked polymers, wood,
bits of coconut and combinations thereof can be usable.
Dimensionally, the undulating channel can have a dimension ranging from 1
micron to 10 cm high, 1 nanometer to 1 mm wide and from 1 nanometer to 100
meters in length.
Between 1 and 5000 undulating channels are contemplated as usable in this
design, however in a preferred embodiment, the fuel cell has 75 undulating
channels. This fuel cell is contemplated to be capable of producing a
voltage between 0.25 volts and 2500 volts, and more preferably between 30
and 60 volts.
In yet another embodiment of the invention, it is contemplated that the
electrolyte can be mounted in the channel at an angle, preferable at an
angle, which is perpendicular to the longitudinal or horizontal axis of
the predominant portion of the porous substrate.
The design of the invention has in an alternative embodiment, either a dead
end version of the fuel cell or a continuous flow version of the fuel cell
having a fuel plenum outlet. If a dead end version of the fuel cell is not
used, then an additional oxidant plenum inlet and/or an additional oxidant
plenum outlet could be used. More than one inlet and outlet are
contemplated as usable.
The invention can be constructed such that the fuel plenum contains a
mixture of, or pure hydrogen gas. It is preferred that the hydrogen gas be
at least 90% hydrogen. Alternatively, the fuel plenum could use an aqueous
solution containing methanol, or possibly formic acid, an aqueous solution
of ammonia, sodium borohydride or combinations of these.
The fuel of the fuel plenum can be contained in a permeable material
contained within the fuel plenum. Alternatively, the fuel plenum can be
made of a solid material with a flow field. The fuel plenum can be a
closed plenum or alternatively, open to the ambient air and be usable in
the invention. The fuel plenum and the oxidant plenum can each have a
variety of shapes, round, elliptoid, rectangular or square. It is
particularly contemplated that the fuel plenum has a rectangular cross
section.
The anode and the cathode of the invention can be created using first a
catalyst layer and forming them on the first channel wall and second
channel walls, or alternatively, the anode and cathode can be created or
separately manufactured and then inserted, or embedded in the channel
walls. The preferred embodiment contemplated using the anode in or on the
first channel wall and the cathode in or on the second channel wall.
Electrolyte usable in this invention can be a gel, a liquid or a solid
material. Various materials are contemplated as usable and include: a
perfluoronated polymer containing sulphonic groups, an aqueous acidic
solution having a ph of at least 7 or similar aqueous acidic solutions, an
aqueous alkaline solution having a ph of at most 4 or a similar alkaline
solution.
The fuel cell is manufactured using a first and second coating on the
porous substrate. These coatings can be the same material or different
materials. The first or second coating can comprise a thin polymer
coating, such as a coating of polytetrafluoroethylene, or polymethyl
methacrylate, however, other polymers are contemplated as usable such as
polyethylene, polypropylene, polybutylene, and copolymer thereof,
cross-linked polymers thereof, as well as various conductive metals.
The first and second catalyst layers that are contemplated as usable in the
invention can be a noble metals, alloys having some noble metals in them,
ruthenium, alloys of ruthenium, and combinations of these materials. It is
contemplated that ternary alloys having at least one noble metal are
usable for good voltage creation. Platinum-ruthenium alloys are also
contemplated as usable in this invention. The catalyst layers should each
have a catalyst loading quantity wherein the amount of catalyst is
different for each layer.
One method for making the fuel cell layer contemplates the following steps:
1. forming a porous substrate having a top and bottom having a first side
and a second side;
2. forming one or more sealant barrier channel(s) in the porous substrate;
3. filling the sealant barrier channel(s) with sealant barrier;
4. coating the top with a first coating;
5. coating the bottom with a second coating;
6. forming one or more undulating channel(s) through the porous substrate,
wherein the undulating channel(s) comprises a first channel wall and a
second channel wall creating at least one formed channel;
7. forming one or more support member in each of the formed channels;
8. depositing catalyst into the first channel wall of each channel forming
a cathode;
9. depositing catalyst into the second channel wall of each channel forming
an anode;
10. filling each of the formed channel(s) with electrolyte;
11. attaching a positive electrical connection on one end to the first side
of the porous substrate, and attaching a negative electrical connection on
one end to the second side of said porous substrate for creating a current
from the fuel cell to an outside source and from the outside source to the
porous substrate;
12. attaching the fuel plenum to the porous substrate;
13. attaching the oxidant plenum to the porous substrate;
14. loading the fuel plenum with fuel and the oxidant plenum with oxidant.
The method can be supplemented using the additional step of forming between
one and a great number of sealant barrier channels and electrolyte
channels in the porous substrate, such as at up to 75 channels, but even
more are contemplated as usable herein.
In this method the undulating channel can be formed by molding, pressure
laminating, or by embossing, etching or even simply saw cutting the porous
substrate. If etching is the step utilized in the method, it is
contemplated that the etching can be performed by laser etching, deep
reactive ion etching, or alkaline etching. In a preferred embodiment, it
is preferred to form support member 26 outside of channel 14 so long as it
connects the two sides of the substrate.
The variations for making the apparatus can be implemented into the method,
for example the method can contemplate using a conductive material for the
sealant barrier and/or an insulation material for the support member.
The method of the invention can further comprising the step of sealing the
plenum outlets and inlets after the fuel and oxidant is loaded into their
respective plenums creating a dead ended fuel cell.
The method can further include in the step of using an electrolyte, using
an electrolyte selected from the group: a perfluoronated polymer
containing sulphonic groups, an aqueous acidic solution having a ph of at
least 7, an aqueous alkaline solution having a ph of at most 4.
Additionally, it is contemplated that the electrolyte layer can be between
100 nanometers and 0.5 mm in thickness, or alternatively simply filling
each undulating channel from first wall to second wall without a gap.
The method contemplates making anodes and cathodes using layers of
catalyst, on the walls of the undulating channels on the porous membrane,
wherein the layers of catalyst range between 1 nanometer and 100 microns
in thickness.
The invention also contemplates a method for making a multi-layer fuel cell
comprising the steps:
1. forming a porous substrate having a top and bottom having a first side
and a second side;
2. forming a sealant barrier channel in the first side and the second side;
3. filling the sealant barrier channel with sealant barrier;
4. coating the top with a first coating;
5. coating the bottom with a second coating;
6. forming an undulating channel through the porous substrate, wherein the
undulating channel comprises a first channel wall and a second channel
wall thereby creating a formed channel having a longitudinal axis;
7. forming a support member in the formed channel;
8. depositing catalyst into the first channel wall forming a cathode;
9. depositing catalyst into the second channel wall forming an anode;
10. filling the formed channel with electrolyte;
11. repeating steps 1 through 10 forming a plurality of substrates each
containing a fuel cell;
12. placing the plurality of substrates in intimate physical and electrical
contact with each other by connecting the sealant barriers of neighboring
substrates and forming a composite fuel cell layer.
Yet another method for making a fuel is contemplated which has the steps
of:
1. forming a first porous substrate;
2. depositing a layer of catalyst onto the porous substrate;
3. depositing a layer of electrolyte on the layer of catalyst forming a
first laminate;
4. forming a second porous substrate;
5. depositing a layer of catalyst onto the second porous substrate forming
a second laminate;
6. placing the first laminate over the second laminate such that the
catalyst layer and the electrolyte layer contact each other;
7. placing a sealant barrier on the second laminate on the side without
catalyst;
8. depositing a third porous substrate on the sealant barrier forming a
first fuel cell laminate;
9. repeating the steps 1 through 8 forming a second fuel cell laminate;
10. assembling the first fuel cell laminate on top of the second fuel cell
laminate forming an assembled laminate;
11. repeating the steps for forming a plurality of fuel cell laminates, and
assembling the additional fuel cell laminates on top of the assembled
laminate forming a fuel cell composite having a top fuel cell laminate;
12. cutting the fuel cell composite into a plurality of fuel cell layers
each having a top and a bottom;
13. depositing a first coating on the top and a second coating on the
bottom;
14. attaching a negative electrical connection on one end of the fuel cell
layer and to an external load on the other end;
15. attaching a positive electrical connection on one end of the fuel cell
layer and to an external load on the other end;
16. attaching a fuel plenum to the top of the fuel cell layer; and
17. attaching an oxidant plenum to the bottom of the fuel cell layer.
The fuel cell of the invention can be used by first, connecting a fuel
source to a fuel plenum inlet; second, connecting a fuel plenum outlet to
a re-circulating controller; third, connecting an oxidant plenum inlet to
an oxidant source; fourth, connecting an oxidant plenum outlet to a flow
control system, fifth, connecting a positive electrical connection and a
negative electrical connection to an external load; sixth, flowing fuel
and oxidant to the inlets; and finally, driving load with electricity
produced by the fuel cell.
It is contemplated that the fuel cell can be used in a system
comprising:(a)a fuel cell having at least one planar surface wherein said
planar surface is used to form a circuit with an electronic component
mounted on said microstructure fuel cell This system contemplates that the
electronic component is a cellular phone, or it could be any one of the
following: a PDA, a satellite phone, a laptop computer, portable DVD,
portable CD player, portable personal care electronics, portable boom
boxes, portable televisions, radar, radio transmitters, radar detectors,
and combinations thereof.
The invention can relate to a phone system having the novel fuel cell
wherein the fuel cell has a planar surface, a circuit formed on the planar
surface; and a telephone communicating with the surface to receive current
from the fuel cell. The telephone can be a cellular phone or a satellite
phone.
The invention has been described in detail with particular reference to
certain preferred embodiments thereof, but it will be understood that
variations and modifications can be effected within the scope of the
invention.
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