U.S. patent application number 09/804083 was filed with the patent office on 2001-11-01 for water electrolytic apparatus.
Invention is credited to Ichikawa, Masao, Nosaki, Katsutoshi, Okabe, Masanori, Urata, Kenta.
Application Number | 20010035345 09/804083 |
Document ID | / |
Family ID | 18594088 |
Filed Date | 2001-11-01 |
United States Patent
Application |
20010035345 |
Kind Code |
A1 |
Nosaki, Katsutoshi ; et
al. |
November 1, 2001 |
Water electrolytic apparatus
Abstract
A water electrolytic apparatus includes, and a plurality of
water electrolytic cells each having a solid polymer electrolyte
membrane, an anode, and a cathode, the anode and the cathode being
arranged on opposite sides of the electrolyte membrane,
respectively. The water electrolytic cells are developed on a
hypothetical plane and electrically connected in series to one
another. In the water electrolytic apparatus, an increase in
electric current can be inhibited.
Inventors: |
Nosaki, Katsutoshi;
(Wako-shi, JP) ; Ichikawa, Masao; (Wako-shi,
JP) ; Okabe, Masanori; (Wako-shi, JP) ; Urata,
Kenta; (Wako-shi, JP) |
Correspondence
Address: |
ARENT FOX KINTNER PLOTKIN & KAHN, PLLC
Suite 600
1050 Connecticut Avenue, N.W.
Washington
DC
20036-5339
US
|
Family ID: |
18594088 |
Appl. No.: |
09/804083 |
Filed: |
March 13, 2001 |
Current U.S.
Class: |
204/257 ;
204/253 |
Current CPC
Class: |
Y02E 60/36 20130101;
C25B 1/04 20130101; C25B 9/70 20210101; C25B 11/00 20130101 |
Class at
Publication: |
204/257 ;
204/253 |
International
Class: |
C25B 009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 14, 2000 |
JP |
2000-76328 |
Claims
What is claimed is:
1. A water electrolytic apparatus comprising a plurality of water
electrolytic cells each having a solid polymer electrolyte
membrane, an anode, and a cathode, the anode and the cathode being
arranged on opposite sides of said electrolyte membrane,
respectively, said water electrolytic cells being developed on a
hypothetical plane and electrically connected in series to one
another.
2. A water electrolytic apparatus according to claim 1, further
including a solar cell serving as a power supply for said plurality
of water electrolytic cells.
3. A water electrolytic apparatus according to claim 1 or 2,
wherein the anodes of the plurality of water electrolytic cells are
disposed on one hypothetical plane, and the cathodes of the
plurality of water electrolytic cells are disposed on another
hypothetical plane, and a single water/oxygen flow path and a
single hydrogen flow path are shared by the plurality of water
electrolytic cells.
4. A water electrolytic apparatus according to claim 2, wherein
said solar cell is of a panel shape and superposed on said
plurality of water electrolytic cells.
5. A water electrolytic apparatus according to claim 3, wherein
said solar cell is of a panel shape and superposed on said
plurality of water electrolytic cells.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a water electrolytic
apparatus used mainly for producing hydrogen.
[0003] 2. Description of the Related Art
[0004] As such an apparatus, a conventional water electrolytic
apparatus is disclosed in Japanese Patent Application Laid-open No.
6-33283.
[0005] A general water electrolytic apparatus has an electrode area
of around hundred square centimeters. If the water electrolytic
apparatus is operated at a current density of 1 A/cm.sup.2,
electric current of several hundred amperes is required, leading to
inevitable loss in ohm and the extreme thickening of a cable. The
thus-required large electric current also leads to a reduction in
efficiency of the converter, for example, in the case where a DC/DC
converter is mounted at an upstream side of an input electric
power. To produce the same amount of hydrogen avoiding these
problems, it is necessary to decrease the electrode area (if the
current density is fixed at 1 A/cm.sup.2, the area is reduced to
1/4, and the current is reduced to 1/4), and to increase the number
of the water electrolytic cells (if the area is reduced to 1/4, the
number of the water electrolytic cells is increased four times
produce the same amount of hydrogen).
[0006] However, if a plurality of water electrolytic cells are
laminated as in the prior art, there is a limit in number of cells
laminated. As the area of the water electrolytic cell is reduced
and the number of the water electrolytic cells is increased, it is
more difficult to maintain uniform performances. When a water
electrolytic apparatus having a power supply is formed by combining
a water electrolytic apparatus of a laminated structure, for
example, with a panel-shaped solar cell, the following problem is
encountered: When the water electrolytic apparatus and the solar
cell are superposed one on another from the demand for the
compactness, the height of the entire system is increased and
hence, the entire system is not suitable to be placed on a roof or
the like.
SUMMARY OF THE INVENTION
[0007] Accordingly, it is an object of the present invention to
provide a water electrolytic apparatus of the above-described type,
which is of a thin type, wherein an increase in electric current is
inhibited, and even when it is superposed on a panel-shaped solar
cell, the height of the entire system can be suppressed to a low
level.
[0008] To achieve the above object, according to the present
invention, there is provided a water electrolytic apparatus
comprising a plurality of water electrolytic cells each having a
solid polymer electrolyte membrane, an anode, and a cathode, the
anode and the cathode being arranged on opposite sides of the
electrolyte membrane, respectively, the water electrolytic cells
being developed on a hypothetical plane and electrically connected
in series to one another.
[0009] With the above arrangement, an increase in electric current
can be inhibited in the water electrolytic apparatus. In addition,
it is possible to ensure that the thickness of the water
electrolytic apparatus is substantially equal to the thickness of
the water electrolytic cells, whereby the thinning of the water
electrolytic apparatus can be achieved. Therefore, if the water
electrolytic apparatus is superposed on a panel-shaped solar cell,
the height of the entire system can be suppressed to a lower
level.
[0010] The above and other objects, features and advantages of the
invention will become apparent from the following description of
the preferred embodiments taken in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a plan view of a plurality of electrolytic cells
in a state in which they have been developed in a single
hypothetical plane;
[0012] FIG. 2 is an enlarged sectional view of an embodiment of a
water electrolytic apparatus, taken along a line 2-2 in FIG. 1;
[0013] FIG. 3 is an exploded perspective view of the embodiment of
the water electrolytic apparatus;
[0014] FIG. 4 is a plan view of another embodiment of a water
electrolytic apparatus; and
[0015] FIG. 5 is an exploded perspective view of the another
embodiment of the water electrolytic apparatus.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] The present invention will now be described by way of
embodiments with reference to the accompanying drawings.
[0017] Referring to FIGS. 1 to 3, a water electrolytic apparatus 1
includes a plurality of water electrolytic cells 2 which are
developed in one hypothetical plane and electrically connected in
series to one another.
[0018] Each of the water electrolytic cells 2 is of a rectangular
parallelepiped shape as a whole and has a laminated structure. As
best shown in FIG. 2, the water electrolytic cell 2 has a solid
polymer electrolyte membrane 3 (for example, Nafion made by du Pont
de Nemours. E.I., and Co.) having a proton conductivity at a
central portion thereof. An current collector 5 having a seal
member 4 around its outer peripheral edge and a plate-shaped anode
7 likewise having a seal member 6 around its outer peripheral edge
are disposed sequentially on an upper surface of the membrane 3. On
the other hand, an current collector 9 having a seal member 8
around its outer peripheral edge and a plate-shaped cathode 11
likewise having a seal member 10 around its outer peripheral edge
are disposed sequentially on a lower surface of the membrane 3. A
catalyst layer 12 containing iridium (Ir) is provided on the upper
surface of the solid polymer electrolyte membrane 3 on the side of
the anode 7, and a catalyst layer 13 containing platinum (Pt) is
provided on the lower surface of the solid polymer electrolyte
membrane 3 on the side of the cathode 11.
[0019] As best shown in FIG.1, a positive terminal 14 existing at
one end of the anode 7 protrudes to the outside from one end face
of the seal member 6. In the cathode 11, a negative terminal 15
existing at the other end opposite the positive terminal 14
protrudes to the outside from the other end face of the seal member
10.
[0020] The plurality of water electrolytic cells 2 are arranged, so
that longer sides of the adjacent cells 2 are parallel to each
other, and the positive terminals 14 (and the negative terminals
15) are disposed in a zigzag fashion. Thus, the anodes 7 of the
water electrolytic cells 2 are disposed on one side, an upper on
hypothetical plane, and the cathodes 11 are disposed on the other
side, a lower hypothetical plane.
[0021] In this case, the number of water electrolytic cells 2 is an
even number, and the positive terminal 14 of the water electrolytic
cell 2 located on one of the outermost sides and the negative
terminal 15 of the water electrolytic cell 2 located on the other
outermost side are disposed on the same side and function as
terminals for connection to a power supply. In the adjacent water
electrolytic cells 2, at each end thereof, the upper positive
terminal 14 and the corresponding lower negative terminal 15 are
connected to each other through a conductive plate 16. Thus, the
plurality of water electrolytic cells 2 are electrically connected
in series to one another.
[0022] As clearly shown in FIGS. 2 and 3, first and second flow
path-defining flat box-shaped members 17 and 18 are disposed
respectively above and below all of the water electrolytic cells 2
to sandwich these water electrolytic cells 2. The inside of the
first flow path-defining member 17 functions as a flow path 19 for
water and oxygen. The first flow path-defining member 17 has a
water supply port 20 in one of sidewalls thereof and a water/oxygen
discharge port 21 in the other sidewall. A plurality of openings 23
are formed in a bottom wall 22 of the member 17 to face the anodes
7, respectively, and each have a peripheral edge put into close
contact with the seal member 6 of each of the anodes 7 in a sealing
manner. Each of the anodes 7 has a plurality of elongated
communication bores 24 which permit the communication between each
of the openings 23 and the current collector 5 and thus the solid
polymer electrolyte membrane 3. The communication bores 24 serve as
water outlets and inlets and as oxygen outlets. The inside of the
second flow path-defining member 18 functions as a hydrogen flow
path 25 and has a hydrogen outlet 26 in one of sidewalls on the
side where the water/oxygen discharge port 21 exists. A plurality
of openings 28 are formed in a ceiling wall 27 to face the cathodes
11 and each have a peripheral edge put into close contact with the
seal member 10 of each of the anodes 11 in a sealing manner. Each
of the cathodes 11 has a plurality of communication bores 29 which
permit the communication between each of the openings 28 and the
current collector 9 and thus the solid polymer electrolyte membrane
3. Each of the communication bores 29 is formed into an elongated
shape, as are the communication bores 24 in the anode 7, and serves
as a hydrogen outlet. Thus, the single water/oxygen flow path 19
and the single hydrogen flow path 25 are shared by the plurality of
water electrolytic cells 2. This can provide the simplification of
a flow path structure and an enhancement in flow path formability,
as compared with a case where two types of independent flow paths
19 and 25 are provided in each of water electrolytic cells 2 so
that the flow paths are connected together in series.
[0023] A panel-shaped solar cell 30 as a power supply is superposed
onto an upper surface of the first flow path-defining member 17. A
lead wire 31 from a positive terminal of the solar cell 30 is
connected to the outermost positive terminal 14 of the water
electrolytic apparatus 1, and a lead wire 32 from a negative
terminal of the solar cell 30 is connected to the outermost
negative terminal 15 of the water electrolytic apparatus 1.
[0024] If the water electrolytic apparatus is constructed as
described above, an increase in electric current can be inhibited
in the water electrolytic apparatus 1. In addition, the thickness
of the water electrolytic apparatus 1 can be made substantially
equal to that of each of the water electrolytic cells 2 and thus,
the thinning of the apparatus 1 can be achieved. Therefore, if the
water electrolytic apparatus 1 is superposed onto the panel-shaped
solar cell 30, the height of the resulting assembly can be
suppressed to a lower level.
[0025] During production of hydrogen, a reaction represented by
H.sub.2O.fwdarw.2H.sup.-+1/2O.sub.2+2e.sup.- occurs on the side of
the anode 7, and a transfer of protons is conducted in the solid
polymer electrolyte membrane 3. Further, a reaction represented by
2H.sup.++2e.sup.-.fwdarw.H.sub.2 occurs on the side of the cathode
11.
[0026] A water electrolytic apparatus shown in FIGS. 4 and 5
includes a plurality of water electrolytic cells 2 developed all
over a single flat plate 33. Each of the water electrolytic cells 2
has a first flow path defining member 17 including water and oxygen
flow paths, and a second flow path defining member 18 including a
hydrogen flow path. The water electrolytic cells 2 in first and
third rows arranged in a left-to-right direction in FIGS. 4 and 5
are placed on the flat plate 33 with the first flow path-defining
member 17 for water and oxygen located on an upper side and with
the second flow path-defining member 18 for hydrogen placed on a
lower side. On the other hand, the water electrolytic cells 2 in
second and fourth rows are placed on the flat plate 33 with the
second flow path-defining member 18 for hydrogen located on an
upper side and with the first flow path-defining member 17 for
water and oxygen placed on a lower side. The positive terminal 14
of the water electrolytic cell 2 at a left end of the first row and
the negative terminal 15 of the water electrolytic cell 2 at a left
end of the fourth row are connected to the power supply. In the
water electrolytic cells 2 in the first and second rows, the anodes
7 and the cathodes 11 are connected in series from the left end to
the right end through conductors 34 in an order of the first
row.fwdarw.the second row.fwdarw.the first row.fwdarw.the second
row --- the second row. In the water electrolytic cells 2 in the
third and fourth rows, the anodes 7 and the cathodes 11 are
connected in series from the right end to the left end through
conductors 35 in an order of the third row.fwdarw.the fourth
row.fwdarw.the third row.fwdarw.the fourth row --- the fourth row.
Further, the cathode 11 of the water electrolytic cell 2 at the
right end of the second row and the anode 7 of the water
electrolytic cell 2 at the right end of the third row are connected
to each other through a conductor 36. Thus, the plurality of water
electrolytic cells 2 are electrically connected in series to one
another. The first flow path-defining members 17 in the water
electrolytic cells 2 at the left ends of the first to fourth rows
are connected to a water supply pipe 38 through conduits 37, and
the first flow path-defining members 17 in the water electrolytic
cells 2 at the right ends of the first to fourth rows are connected
to a water/oxygen discharge pipe 40 through conduits 39. Further,
the first flow path-defining members 17 of the adjacent water
electrolytic cells 2 in each of the rows are connected to each
other through a conduit 41.
[0027] The second flow path-defining members 18 of the water
electrolytic cells 2 at the right ends of the first to fourth rows
are connected to a hydrogen discharge pipe 43 through conduits 42.
Further, the second flow path-defining members 18 of the adjacent
water electrolytic cells 2 in each of the rows are connected to
each other through a conduit 44.
[0028] Although the embodiments of the present invention have been
described in detail, it will be understood that the present
invention is not limited to the above-described embodiments, and
various modifications in design may be made without departing from
the spirit and scope of the invention defined in claims.
* * * * *