JP2021178999A - Water electrolysis stack - Google Patents

Abstract

To provide a water electrolysis stack having excellent durability.SOLUTION: The water electrolysis stack comprises: an anode separator having high potential resistance; a membrane electrode composite comprising a pair of electrodes each disposed on either side of an electrolyte membrane; a cathode separator having hydrogen resistance; and an anode inlet manifold, an anode outlet manifold, and a cathode manifold each mutually independently disposed outside the membrane electrode composite. The anode separator comprises: an anode side inlet communicating with the anode inlet manifold and a first gap; and an anode side outlet communicating with the first gap and the anode outlet manifold. The cathode separator comprises a cathode side outlet communicating with a second gap and the cathode manifold. The water electrolysis stack further comprises: an anode side sealing part constituting the anode inlet manifold and the anode outlet manifold together with the anode separator; and a cathode side sealing part constituting the cathode manifold together with the cathode separator.SELECTED DRAWING: Figure 1B

Description

The present disclosure relates to a water electrolysis stack.

In recent years, effective use of renewable energy such as solar power or wind power has become important for effective use of energy and reduction of _{CO 2 emissions.} For example, a system that stores hydrogen generated by electrolyzing water with electricity obtained from solar power generation as hydrogen gas, and uses this hydrogen gas to drive a fuel cell to obtain electricity when necessary. There is.

In the system, hydrogen is generated, for example, by a water electrolysis stack using a polyelectrolyte membrane. However, the water electrolysis stack is particularly susceptible to deterioration and low durability as compared with the fuel cell stack because the front and back of the multi-pole plate separator in the water electrolysis stack are exposed to high potential water and generated hydrogen, respectively. There is.

In order to improve the durability of the water electrolysis stack, Patent Document 1 discloses that a titanium plate having high potential resistance and a stainless steel plate having hydrogen resistance are laminated and used as a multi-pole plate separator.

Japanese Patent No. 3072333

However, in the water electrolysis stack described in Patent Document 1, the titanium plate and the stainless steel plate are exposed to high-potential water and generated hydrogen gas, respectively. Therefore, it may not be possible to sufficiently improve the durability of the water electrolysis stack.

The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a water electrolysis stack having excellent durability.

The water electrolysis stack of the present disclosure is provided on both sides of an anode separator having high potential resistance, a cathode separator having hydrogen resistance facing the anode separator and arranged at intervals, and an electrolyte membrane and an electrolyte membrane, respectively. Of the membrane electrode composite having the electrodes and arranged between the anode separator and the cathode separator, and the membrane electrode composite in a direction intersecting the arrangement direction of the anode separator, the cathode separator and the membrane electrode composite. It includes an anode inlet manifold, an anode outlet manifold, and a cathode manifold provided independently of each other on the outside. Each of the anode separator and the cathode separator has a central portion facing the membrane electrode complex in the arrangement direction and an outer peripheral portion of the central portion arranged outside in a direction intersecting the arrangement direction. .. The anode separator is provided in the central portion of the anode separator, penetrates the central portion of the anode separator in the arrangement direction, and has a first gap between the anode inlet manifold and the anode separator and the membrane electrode composite. An anode-side inlet that communicates with the anode side inlet, and an anode-side outlet that is provided in the central portion of the anode separator and penetrates the central portion of the anode separator in the arrangement direction and communicates with the first gap and the anode outlet manifold. , Have. The cathode separator is provided in the central portion of the cathode separator, penetrates the central portion of the cathode separator in the arrangement direction, and is a gap between the membrane electrode composite and the cathode separator, and is the membrane electrode. It has a cathode-side outlet that communicates with the cathode manifold and the second gap partitioned from the first gap by the composite. The water electrolysis stack further includes an anode-side sealing portion that constitutes the anode inlet manifold and the anode-outlet manifold together with the anode separator, and a cathode-side sealing portion that constitutes the cathode manifold together with the cathode separator.

According to the present disclosure, it is possible to provide a water electrolysis stack having excellent durability.

The front view of the water electrolysis stack which concerns on 1st Embodiment of this disclosure. FIG. 6 is a cross-sectional view taken along the line α1 of FIG. 1A. FIG. 6 is a cross-sectional view taken along the line β1 of FIG. 1A. The schematic diagram of the withstand voltage performance evaluation apparatus used in the Example of this disclosure. The schematic diagram of the water electrolysis performance evaluation apparatus used in the Example of this disclosure. The graph which shows the voltage ratio transition of the Example and the comparative example of this disclosure. FIG. 6 is a cross-sectional view taken along the line α1 of FIG. 1A of the water electrolysis stack according to the second embodiment of the present disclosure. FIG. 6 is a cross-sectional view taken along the line β1 of FIG. 1A of the water electrolysis stack according to the second embodiment of the present disclosure. FIG. 6 is a cross-sectional view taken along the line β1 of FIG. 1A of the water electrolysis stack according to the third embodiment of the present disclosure. FIG. 6 is a cross-sectional view taken along the line β1 of FIG. 1A of the water electrolysis stack according to the third embodiment of the present disclosure. The perspective view of the water electrolysis stack of the comparative example. Front view of the water electrolysis stack of the comparative example. FIG. 6B is a cross-sectional view taken along the line α. FIG. 6B is a cross-sectional view taken along the line β. FIG. 6B is a cross-sectional view taken along the line γ. Sectional drawing along the line δ of FIGS. 7B and 7C.

The water electrolysis stack of the present disclosure is provided on both sides of an anode separator having high potential resistance, a cathode separator having hydrogen resistance facing the anode separator and being spaced apart from each other, and an electrolyte membrane and an electrolyte membrane, respectively. The membrane electrode composite having an electrode and arranged between the anode separator and the cathode separator and the outside of the membrane electrode composite in the direction intersecting the arrangement direction of the anode separator, the cathode separator and the membrane electrode composite are mutually independent. The anode inlet manifold, the anode outlet manifold, and the cathode manifold are provided. Each of the anode separator and the cathode separator has a central portion facing the membrane electrode complex in the arrangement direction and an outer peripheral portion arranged outside in the direction intersecting the arrangement direction of the central portion. The anode separator is provided at the center of the anode separator, and has an anode-side inlet that penetrates the center of the anode separator in the arrangement direction and communicates with the anode inlet manifold and the first gap between the anode separator and the membrane electrode composite. It is provided in the central portion of the anode separator and has an anode side outlet which penetrates the central portion of the anode separator in the arrangement direction and communicates the first gap and the anode outlet manifold. The cathode separator is provided in the central portion of the cathode separator, penetrates the central portion of the cathode separator in the arrangement direction, and is a gap between the membrane electrode composite and the cathode separator. It has a cathode side outlet that communicates with the partitioned second gap and the cathode manifold. The water electrolysis stack further includes an anode-side sealing portion that constitutes an anode inlet manifold and an anode-outlet manifold together with an anode separator, and a cathode-side sealing portion that constitutes a cathode manifold together with a cathode separator.

In the water electrolysis stack of the present disclosure having the above-described configuration, the cathode gas containing hydrogen gas is a gap between the membrane electrode composite and the cathode separator, and the second gap is partitioned by the membrane electrode composite. It flows from the gap through the cathode side outlet to the cathode manifold composed of the cathode separator and the cathode manifold seal, and does not touch the cathode separator. Therefore, hydrogen embrittlement of the anode separator can be prevented. On the other hand, for example, the high-potential water is a gap between the anode separator and the membrane electrode composite via the anode inlet manifold and the anode side inlet, and is partitioned from the second gap by the membrane electrode composite. Since it flows through the gap and flows from the first gap through the anode side outlet to the anode outlet manifold, it does not come into contact with the cathode separator. Therefore, high potential corrosion of the cathode separator can be prevented. As a result, the durability of the water electrolysis stack is improved.

Further, the anode manifold and the cathode manifold are formed on the outer side in the direction intersecting the arrangement direction of the membrane electrode composite, and the membrane electrode composite arranged to face the central portion of the anode separator and the cathode separator includes the anode manifold and the cathode manifold. The manifold is not formed. That is, the electrolyte membrane does not include a manifold. This makes the electrolyte membrane in the water electrolysis stack of the present disclosure less likely to be directly exposed to fluids such as gas and high potential water, as compared to a typical electrolyte membrane formed including a manifold. Therefore, for example, even if the potential application is stopped when the operation of the water electrolysis stack is stopped, the cathode gas containing hydrogen gas permeates and diffuses through the electrolyte membrane on the anode side and causes a combustion reaction with oxygen on the anode side to cause the electrolyte membrane. Can be prevented from being damaged. As a result, the durability of the membrane electrode complex can be improved, and the durability of the water electrolysis stack can be improved. In addition, since the membrane electrode composite does not include a manifold, the size can be made smaller than that of a general electrolyte membrane formed by including the manifold, and the manufacturing cost of the water electrolysis stack can be reduced.

Further, in the present disclosure, the anode side inlet, the anode side outlet and the cathode side outlet are formed in the central portion of the anode separator and the cathode separator. Therefore, the sizes of the anode side inlet, the anode side outlet, and the cathode side outlet can be sufficiently increased with respect to the thickness of the gas diffusion layer covering the surface of the membrane electrode complex. As a result, the pressure loss of gas, high-potential water, etc. can be reduced. Therefore, for example, when the water electrolysis stack of the present disclosure is applied to a hydrogen generator, a water circulation pump installed in the hydrogen generator, etc. It is also possible to reduce the load on the auxiliary device and improve the device efficiency of the hydrogen generator.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

<First Embodiment>
1A shows a front view of the water electrolysis stack 1 according to the first embodiment, FIG. 1B shows a cross-sectional view taken along line α1 of FIG. 1A, and FIG. 1C shows a cross-sectional view taken along line β1 of FIG. 1A. .. As shown in FIG. 1A, an anode inflow port 2a, a cathode discharge port 2b, and an anode discharge port 2c are formed on the surface of the water electrolysis stack 1.

As shown in FIGS. 1B and 1C, the water electrolysis stack 1 of the present embodiment includes an anode separator 4c having high potential resistance, a cathode separator 4d having hydrogen resistance, a membrane electrode composite 5, and an anode inlet manifold 2a1. , The anode outlet manifold 2c1 and the cathode manifold 2b1 are provided. The cathode separator 4d is arranged so as to face the anode separator 4c and at intervals in the thickness direction. The membrane electrode composite 5 is arranged between the anode separator 4c and the cathode separator 4d. The anode inlet manifold 2a1, the anode outlet manifold 2c1 and the cathode manifold 2b1 are the film electrode composite 5 in a direction intersecting the arrangement direction of the anode separator 4c, the cathode separator 4d and the membrane electrode composite 5 (hereinafter, simply referred to as the arrangement direction). It is provided independently of each other on the outside of the. The anode inlet manifold 2a1 is connected to the anode inlet 2a, the anode outlet manifold 2c1 is connected to the anode outlet 2c, and the cathode manifold 2b1 is connected to the cathode outlet 2b. The membrane electrode composite 5 has an electrolyte membrane and an anode electrode and a cathode electrode provided on both sides of the electrolyte membrane in the thickness direction, respectively. An anode gas diffusion layer 11a and a cathode gas diffusion layer 11b are attached to both sides of the membrane electrode composite 5 in the thickness direction by heat welding. The anode gas diffusion layer 11a is arranged in the first gap 31 described later, and the cathode gas diffusion layer 11b is arranged in the second gap 32 described later. The membrane electrode composite 5 and the anode separator 4c and the cathode separator 4d that sandwich the membrane electrode composite 5 form a single cell. In the present embodiment, the water electrolysis stack 1 is composed of three single cells 60 stacked in the arrangement direction. Anode end separators 4ca and cathode end separators 4da are arranged on both sides of the three single cells 60 in the arrangement direction. The anode insulating plate 6a and the cathode insulating plate 6b are arranged on both sides of the anode end separator 4ca and the cathode end separator 4da in the arrangement direction, and the positive electrode side is further outside in the arrangement direction of the anode insulating plate 6a and the cathode insulating plate 6b. The end plate 7a and the negative electrode side end plate 7b are arranged. In the water electrolysis stack 1, each component constituting the water electrolysis stack 1 is pressurized so as to be in close contact with each other in the arrangement direction, and this pressurized state is maintained by being tightened by the bolt 8 and the nut 9. The water electrolysis stack 1 is not limited to the case of being composed of three single cells 60, and may be composed of one or two single cells 60, or may be composed of four or more single cells 60. You may.

The outer peripheral ends of the membrane electrode composite 5 in the direction intersecting the arrangement direction are surrounded by the resin frames 15a and 15b. The resin frames 15a and 15b are integrated with the membrane electrode composite 5 by heat welding. As the material of the resin frames 15a and 15b, for example, a thermoplastic resin can be used.

The anode separator 4c is made of a material having high potential resistance (for example, a material containing titanium). The material having high potential resistance means a material that is not yet ionized at the potential at which hydrogen gas is ionized. The anode separator 4c has a thin plate shape as an example, and has a central portion facing the membrane electrode composite 5 in the arrangement direction and an outer peripheral portion arranged on the outer side in a direction intersecting the arrangement direction of the central portion. At the central portion of the anode separator 4c, an anode side inlet 4ci and an anode side outlet 4cx penetrating the central portion of the anode separator 4c in the arrangement direction are provided. The anode side inlet 4ci is arranged in the vicinity of the anode inlet manifold 2a1 and communicates with the anode inlet manifold 2a1 and the first gap 31 between the anode separator 4c and the membrane electrode composite 5. The anode side outlet 4cx is arranged in the vicinity of the anode outlet manifold 2c1 and communicates with the first gap 31 and the anode outlet manifold 2c1. The first gap 31 is filled with the anode gas diffusion layer 11a except for both ends in the direction intersecting the arrangement direction.

The cathode separator 4d is made of a material having hydrogen resistance (for example, a material containing stainless steel or carbon). When improving the hydrogen resistance, it is preferable to form the cathode separator 4d with a material containing carbon. Further, in order to improve the strength, it is preferable to form the cathode separator 4d with a material containing stainless steel. The cathode separator 4d has a thin plate shape as an example, and has a central portion facing the membrane electrode composite 5 in the arrangement direction and an outer peripheral portion arranged on the outer side in a direction intersecting the arrangement direction of the central portion. A cathode side outlet 4dx that penetrates the central portion of the cathode separator 4d in the arrangement direction is provided at the central portion of the cathode separator 4d. The cathode side outlet 4dx is arranged in the vicinity of the cathode manifold 2b1 and communicates with the second gap 32 between the membrane electrode composite 5 and the cathode separator 4d and the cathode manifold 2b1. The second gap 32 is partitioned from the first gap 31 by the membrane electrode composite 5, and is filled with the cathode gas diffusion layer 11b except for both ends in the direction intersecting the arrangement direction.

The water electrolysis stack 1 further includes an anode-side sealing portion 40 and a cathode-side sealing portion 50. The anode-side sealing portion 40 constitutes the anode inlet manifold 2a1 and the anode outlet manifold 2c1 together with the anode separator 4c. The anode inlet manifold 2a1 and the anode outlet manifold 2c1 are provided for each single cell 60 as shown in FIG. 1B. The anode inlet manifold 2a1 and the anode outlet manifold 2c1 corresponding to each single cell 60 are connected to each other via a through hole 71 provided in the outer peripheral portion of the anode separator 4c. Further, the cathode side sealing portion 50 constitutes a cathode manifold 2b1 together with the cathode separator 4d. As shown in FIG. 1C, the cathode manifold 2b1 is provided for each single cell 60. The cathode manifolds 2b1 corresponding to each single cell 60 are connected to each other via a through hole 72 provided in the outer peripheral portion of the cathode separator 4d.

As an example, the anode-side sealing portion 40 has an anode electrode seal 12b, an anode manifold seal 12e, and a manifold seal covering portion 12f. The anode electrode seal 12b seals between the anode separator 4c and the resin frame 15a. As a result, the fluid is prevented from flowing out from the first gap 31 through the space between the anode separator 4c and the resin frame body 15a in the direction intersecting the arrangement direction of the resin frame body 15a. The anode manifold seal 12e is arranged on the outer peripheral portion of the anode separator 4c and extends along the arrangement direction. The anode manifold seal 12e is provided between the anode end separator 4ca and the outer peripheral portion of the anode separator 4c, between the outer peripheral portions of the adjacent anode separators 4c, and between the outer peripheral portion of the anode separator 4c and the cathode end separator 4da, respectively. It is sealed. The manifold seal covering portion 12f is arranged between the membrane electrode composite 5 and the anode manifold seal 12e in a direction in which a part thereof intersects in the arrangement direction, and seals between the anode separator 4c and the cathode separator 4d. There is. Further, the manifold seal covering portion 12f, together with the anode separator 4c, has a flow path 33 connecting the anode inlet manifold 2a1 and the anode side inlet 4ci, and a flow path 34 connecting the anode outlet manifold 2c1 and the anode side outlet 4cx. It is composed.

As an example, the cathode side sealing portion 50 has a cathode electrode seal 12c, a cathode manifold seal 12d, and a manifold seal covering portion 12f. The cathode electrode seal 12c seals between the cathode separator 4d and the resin frame body 15b. As a result, the fluid is prevented from flowing out from the second gap 32 through the space between the cathode separator 4d and the resin frame body 15b in the direction intersecting the arrangement direction of the resin frame body 15a. The cathode manifold seal 12d is arranged on the outer peripheral portion of the cathode separator 4d and extends along the arrangement direction. The cathode manifold seal 12e seals between the anode end separator 4ca and the outer peripheral portion of the cathode separator 4d, and between the outer peripheral portions of the adjacent cathode separator 4d, respectively. The manifold seal covering portion 12f is arranged between the membrane electrode composite 5 and the cathode manifold seal 12d in a direction in which a part thereof intersects in the arrangement direction, and seals between the anode separator 4c and the cathode separator 4d. There is. Further, the manifold seal covering portion 12f, together with the cathode separator 4d or the anode end separator 4ca, constitutes a flow path 35 connecting the cathode side outlet 4dx and the cathode manifold 2b1.

The materials of the cathode manifold seal 12d and the anode manifold seal 12e are not particularly limited, and for example, rubber or the like can be used. For the cathode manifold seal 12d and the anode manifold seal 12e, a surface seal, an O-ring or a lip ring can be used, but it is preferable to use an O-ring or a lip ring. By using an auring or lip ring having a high contact peak surface pressure as the cathode manifold seal 12d and the anode manifold seal 12e, the amount of hydrogen that can be stored in the water electrolysis stack 1 can be increased.

The contact point of the anode electrode seal 12b with respect to the resin frame body 15a and the contact point of the cathode electrode seal 12c with respect to the resin frame body 15b are preferably located on a straight line extending in the arrangement direction. In this case, since the peak surface pressure due to the elasticity of the anode electrode seal 12b and the cathode electrode seal 12c is transmitted to the membrane electrode composite 5, fluid leakage, in particular, high potential water and the anode gas which are the fluids on the anode side and the cathode side Mixing with the cathode gas, which is a fluid (cross leak), can be prevented.

<Second Embodiment>
The front view of the water electrolysis stack 1 of the second embodiment is the same as that of FIG. 1A, FIG. 4A shows a cross-sectional view taken along line α1 of FIG. 1A, and FIG. 4B shows a cross-sectional view taken along line β1 of FIG. 1A. show. The same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In the present embodiment, the water electrolysis stack 1 is provided outside in the direction intersecting the arrangement direction of the cathode manifold seal 12d, and further includes a cathode side support wall for supporting the cathode manifold seal 12d. As an example, the cathode side support wall has a cylindrical shape and is composed of two cylinders (hereinafter, referred to as a first cylinder 4e1 and a second cylinder 4e2). The first cylinder 4e1 extends from the outer peripheral portion of the cathode separator 4d toward the cathode discharge port 2b along the arrangement direction. The second cylinder 4e2 extends from the outer peripheral portion of the cathode separator 4d or the anode end separator 4ca along the arrangement direction in the opposite direction to the first cylinder 4e1. The space between the first cylinder 4e1 and the second cylinder 4e2 is sealed by a seal member 51 protruding from the cathode manifold seal 12d. The first cylinder 4e1 and the second cylinder 4e2 suppress the expansion of the cathode manifold seal 12d even when the pressure in the space inside the cathode manifold 2b1 rises, and the cathode manifold seal 12d is displaced, so that the fluid on the anode side is displaced. And / or it is possible to prevent the leakage of the fluid on the cathode side.

In this embodiment, as shown in FIG. 4A, the support wall for supporting the anode separator 4c is not provided like the cathode manifold seal 12d. However, the water electrolysis stack 1 may be provided outside the direction intersecting the arrangement direction of the anode manifold seal 12e, and may further include an anode side support wall that supports the anode manifold seal 12e. In this case, even when the pressure in the space inside the anode inlet manifold 2a1 and the anode outlet manifold 2c1 rises, the anode manifold seal 12e is suppressed from swelling and the anode manifold seal 12e is displaced, so that the fluid on the anode side and / Alternatively, it is possible to prevent the leakage of the fluid on the cathode side. Of course, the water electrolysis stack 1 may include only one of the cathode side support wall and the anode side support wall, or may include both the cathode side support wall and the anode side support wall.

<Third Embodiment>
The front view of the water electrolysis stack 1 of the third embodiment is the same as that of FIG. 1A, FIG. 5A shows a cross-sectional view taken along line α1 of FIG. 1A, and FIG. 5B shows a cross-sectional view taken along line β1 of FIG. 1A. show. The same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In the present embodiment, the anode manifold seal 12e is composed of a thermoplastic anode manifold seal block 12ga (an example of a resin block) and an O-ring 12h1. Further, the cathode manifold seal 12d is composed of a thermoplastic cathode manifold seal block 12gb (an example of a resin block) and an auring 12h1. The O-rings 12h1 are arranged at both ends of the anode manifold seal block 12ga and the cathode manifold seal block 12gb, respectively. Further, in the present embodiment, the anode electrode seal 12b and the cathode electrode seal 12c are made of a resin block and are integrally formed with the resin frames 15a and 15b, respectively. O-rings 12h2 are arranged at the tip of the anode electrode seal 12b and the tip of the cathode electrode seal 12c, respectively. In the present embodiment, the manifold seal covering portion 12f is also composed of a resin block, and O-rings 12h3 are arranged at both ends of the manifold seal covering portion 12f.

As described above, in the present embodiment, the anode manifold seal 12e is composed of the thermoplastic anode manifold seal block 12ga and the Oling 12h1, and the cathode manifold seal 12d is the thermoplastic cathode manifold seal block 12gb and the Oling 12h1. It is configured. Since the O-ring 12h1 is unlikely to cause misalignment, it is possible to prevent the leakage of the fluid on the anode side and / or the fluid on the cathode side even when the pressure inside the cathode outlet manifold 2b1 rises. The same effect can be obtained by forming the anode electrode seal 12b, the cathode electrode seal 12c, and the manifold seal covering portion 12f with the resin block and the Olling 12h2, 12h3.

Further, in the present embodiment, as the resin blocks such as the anode manifold seal block 12ga and the cathode manifold seal block 12gb, a lightweight and inexpensive thermoplastic resin such as PP or PPE can be used. Therefore, the manufacturing cost can be reduced as compared with the case where the entire resin block such as the cathode manifold seal 12d and the anode manifold seal 12e is made of a material such as fluorine rubber.

Hereinafter, examples of the present disclosure will be described.

<Making a water electrolysis stack>
(Example 1)
The water electrolysis stack 1 shown in FIGS. 1B and 1C was produced. The anode separator 4c was formed by using a pure titanium plate as a material and pressing the pure titanium plate. The cathode separator 4d was formed by using a stainless SUS316L plate as a material and pressing the stainless SUS316L plate. Then, the anode electrode seal 12b and the cathode manifold seal 12d were attached to the anode separator 4c by in-third molding. Further, the cathode electrode seal 12c and the anode manifold seal 12e were attached to the cathode separator 4d by in-third molding. As the material of the cathode manifold seal 12d and the anode manifold seal 12e, a molded rubber material was used.

(Example 2)
The water electrolysis stack 1 shown in FIGS. 4A and 4B was produced. In Example 2, as the material of the cathode separator 4d, a compression-molded product of carbon obtained by compression-molding a material paste obtained by kneading a thermosetting resin with powder carbon with a mold equipped with a heating device was used. The configurations other than the cathode separator 4d were prepared using the same materials and methods as in Example 1.

(Example 3)
The water electrolysis stack 1 shown in FIGS. 5A and 5B was produced. In Example 3, the anode electrode seal 12b, the cathode electrode seal 12c, the cathode manifold seal 12d, the anode manifold seal 12e, and the manifold seal covering portion 12f were formed using the thermoplastic resin and the Oling. The configurations other than the anode-side sealing portion 40 and the cathode-side sealing portion 50 were manufactured using the same materials and methods as in Example 1.

(Comparative Example 1)
The water electrolysis stack 100 shown in FIGS. 6A and 6B was produced. Similar to Examples 1 to 3, the water electrolysis stack 100 of Comparative Example 1 has an anode inlet 102a, a cathode outlet 102b, and an anode outlet 102c formed on the surface thereof. 7A-7C show cross-sectional views along lines α, β, γ in the front view of FIG. 6B.

The water electrolysis stack of Comparative Example 1 has a structure in which four double electrode plates 4 and three membrane electrode composites 105 are alternately laminated, and the heat insulating material 10 is arranged on the outermost periphery of the water electrolysis stack. .. The multi-pole plate 4 is composed of an anode separator 4a of a pure titanium plate laminated in the thickness direction and a cathode separator 4b of a stainless SUS316L plate. A seal 112 is arranged between each double electrode plate 4 and each film electrode complex 105. The anode inlet manifold 102a1, the cathode outlet manifold 102b1, and the anode outlet manifold 102c1 are composed of a membrane electrode composite 105, a manifold seal 112a, and a porous spacer 14 through which a fluid can pass, and a gas diffusion layer is provided via the porous spacer 14. The structure is such that the fluid can move between the 111a and 111b. In the water electrolysis stack 100 of Comparative Example 1, as shown in FIG. 7D, the anode inlet manifold 102a1, the cathode outlet manifold 102b1, the anode outlet manifold 102c1 and the gas diffusion layers 111a and 111b have the seal 112 and the membrane electrode composite 105. It is arranged inside the contact line 13 with the electrolyte membrane. The outer line 105a indicates the outer line of the membrane electrode complex 105.

<Evaluation test>
The apparatus used for the evaluation of the water electrolysis stacks 1, 100 of Examples 1 to 3 and Comparative Example 1 will be described.

(Withstand voltage performance evaluation device)
FIG. 2A shows a schematic diagram of the withstand voltage performance evaluation device 16a of the water electrolysis stacks 1,100. In the pressure resistance performance evaluation device 16a, the nitrogen cylinder 17 and the cathode discharge port 2b of the water electrolysis stack 1 are connected by a pipe, and the two-way valve 18 is opened to supply nitrogen at a pressure set in the pipe path. In the middle of the pipe, the auto pressure regulator 19 that can flow the nitrogen required for the outlet pressure to the set value from the nitrogen cylinder 17 to the water electrolysis stacks 1 and 100, and the flow rate of nitrogen flowing through the pipe are measured. A flow meter 20 is installed. When evaluating the withstand voltage performance of the water electrolysis stacks 1, 100, a predetermined pressure is set in the auto pressure regulator 19, the pressure indicated by the pressure gauge 21 becomes constant, and the value of the flow meter 20 is recorded when the flow rate is stable. do. This flow rate indicates the flow rate of nitrogen required to maintain a set pressure in the cathode path of the water electrolysis stacks 1,100. The set pressure of the auto pressure regulator 19 is gradually increased, and the flow rate is recorded accordingly. When the flow rate exceeds a certain value, the pressure immediately before that is the limit of the withstand voltage performance of the water electrolysis stack 1,100. This pressure is set as the limit pressure of the water electrolysis stacks 1,100.

(Water electrolysis performance evaluation device)
FIG. 2B shows a schematic diagram of the water electrolysis performance evaluation device 16b of the water electrolysis stacks 1, 100. In the water electrolysis performance evaluation device 16b, water is circulated between the anode-side gas-liquid separation device 23a and the anode-side fluid flow sections of the water electrolysis stacks 1 and 100 by the pump 22. The anode-side gas-liquid separation device 23a separates a mixture of oxygen and water discharged from the anode discharge port 2c of the water electrolysis stacks 1 and 100, and circulates the separated water to the anode inlet 2a. Further, the separated oxygen is sent to the anode diluting device 24a. Anode Your company nine device 24a mixes oxygen sent from the anode side gas-liquid separation device 23a with nitrogen supplied from the nitrogen cylinder 17 to dilute it, and exhausts it to the outside through the exhaust port 26. Similar to the anode-side air-liquid separation device 23a, the cathode-side air-liquid separation device 23b also separates hydrogen containing water discharged from the cathode discharge port 2b of the water electrolysis stacks 1 and 100 into dry hydrogen and water. After the water is separated, the dry hydrogen is once accumulated in the gas phase portion in the cathode side gas-liquid separation device 23b. When the pressure in the gas-liquid separation device 23b on the sword side becomes equal to or higher than the set value of the auto pressure regulator 19, the dry hydrogen is flowed to the cathode diluting device 24b, mixed with nitrogen supplied from the nitrogen cylinder 17, and diluted. It is exhausted to the outside through the exhaust port 26. On the other hand, the separated water is stored in the liquid phase of the cathode side hydrogen liquid separation device 23b and drained after the operation is completed. In the operation of the water electrolysis stacks 1 and 100, when the power supply device 25 is started and a voltage is applied between the positive electrode 3a and the negative electrode 3b of the water electrolysis stacks 1 and 100, a current flows. The voltage and current of the water electrolysis stacks 1 and 100 are measured by an ammeter 25a and a voltmeter 25b. During the operation of the water electrolysis stacks 1 and 100, the voltage is adjusted by the power supply device 25 so that the current becomes a constant value.

(Evaluation process)
The evaluation process of the water electrolysis stacks 1, 100 of Examples 1 to 3 and Comparative Example 1 will be described.
(1) The water electrolysis stacks 1, 100 are connected to the pressure resistance performance evaluation device 16a, and the critical pressure is measured. For safety, confirm that this limit pressure is an absolute pressure, which is four times or more the pressure normally used as a water electrolyzer. The pressure commonly used as a water electrolyzer was 0.9 (MPa).
(2) The water electrolysis stack is connected to the water electrolysis performance evaluation device 16b.
(3) The two-way valve 18 of the two nitrogen cylinders 17 is opened, and nitrogen is allowed to flow through the anode diluting device 24a and the cathode diluting device 24b. The flowing nitrogen is exhausted to the outside through the exhaust port 26.
(4) The pump 22 is started to circulate water between the anode-side gas-liquid separation device 23a and the fluid flow portion on the anode side of the water electrolysis stacks 1 and 100.
(5) The pressure of the auto pressure regulator 19 is set to a pressure that is commonly used as a water electrolyzer.
(6) In this state, a voltage is applied between the positive electrode 3a and the negative electrode 3b of the water electrolysis stacks 1,100 by the power supply device 25, and the flowing current is measured by the ammeter 25a.
(7) The voltage of the power supply device 25 is adjusted so that the value obtained by dividing the measured current by the area of the electrodes of the water electrolysis stacks 1, 100 becomes a constant value, and the voltage of the voltmeter 21 becomes the set value. Moreover, the voltage value when the voltage indicated by the voltmeter 25b becomes stable is recorded.
(8) The operation is continued for 5 minutes with the voltage adjusted, and the power supply device 25 is stopped.
(9) After continuing the stopped state for 5 minutes, the process returns to the energization operation of (5).
(10) After performing the energization and stop operations of (6) to (9) a specified number of times, the operation of the pump 22 and the operation of the diluting devices 24a and 24b are continued for about 30 minutes in the energization stop state. After the hydrogen and oxygen inside the water electrolysis stacks 1,100 are sufficiently exhausted, the pump 22 is stopped, the two-way valves 18 of the diluting devices 24a and 24b are closed, and the water electrolysis stacks 1,100 are removed for the experiment. finish.

(Evaluation results)
Table 1 shows the values obtained by dividing the critical pressure measured in the above process (1) by the pressure commonly used as a water electrolyzer for Examples 1 to 3 and Comparative Example 1 as a safety magnification.

As shown in Table 1, the safety ratio was larger in the water electrolysis stacks 1 of Examples 1 to 3 than in the water electrolysis stack 100 of Comparative Example 1.

For Examples 1 and 2 and Comparative Example 1, the voltage ratio based on the voltage value recorded in (6) obtained by repeating the above processes (5) to (8) is shown in FIG. The voltage ratio is the voltage value after adjusting so that the value obtained by dividing the current value measured in (5) by the electrode area of the water electrolysis stacks 1,100 is 2.0 (A / cm ^2). Is divided by a predetermined value. The water electrolysis stack of Example 3 has the same result as that of Example 1, and is not shown in FIG.

The polygonal line L in FIG. 3 shows the evaluation result of the water electrolysis stack 100 of Comparative Example 1. According to the polygonal line L, when the energization and stop operations were repeated about 700 times, the voltage ratio suddenly increased and the voltage value exceeded the safety limit of 3, so the energization was stopped. This is because the hydrogen gas generated in the header region η1 of the water electrolysis stack 100 of Comparative Example 1 shown in FIG. 7D and the cathode region on the cathode side facing each other across the membrane electrode composite 105 is the electrolyte membrane of the membrane electrode composite 105. In the evaluation process (7), hydrogen gas diffused from the cathode to the anode region, causing a combustion reaction with the oxygen in the anode and damaging the electrolyte membrane, resulting in a minute cross leak between the two electrodes. It is considered that this is because a higher voltage is required to carry out the water electrolysis reaction of (6).

On the other hand, in the broken line L1 showing the evaluation result of the water electrolysis stack 1 of Example 1, although a slight increase in voltage is observed, the voltage ratio changes sharply even if the energization and stop operations are performed about 1300 times. There wasn't. This is because the generated hydrogen gas has a structure that does not easily come into direct contact with the electrolyte membrane, and the hydrogen gas permeates and diffuses through the electrolyte membrane, causing a combustion reaction or cross leak. It is thought that this is because it is difficult.

Further, in the broken line L2 showing the evaluation result of the water electrolysis stack 1 of Example 2, the voltage ratio is slightly higher than that of the water electrolysis stack 1 of Example 1. It is considered that this is because the resistivity as a material of carbon is larger than that of SUS316L used in Example 1. However, this difference was small, and the deterioration of the performance of the water electrolysis stack 1 was not a problem, and there was no sudden change in the voltage ratio even when the energization and stop operations were performed about 1300 times.

The water electrolysis stack of the present disclosure can be used in a hydrogen generator that electrolyzes water by electric power to generate hydrogen. Further, the water electrolysis stack of the present disclosure can also be used for a fuel cell stack and an electrochemical hydrogen pump that electrochemically compresses hydrogen by electric power.

1,100 Water Electrolysis Stack 2a Anode Inlet 2b Anode Outlet 2c Anode Outlet 2a1 Anode Inlet Manifold 2b1 Anode Outlet Manifold 2c1 Anode Outlet Manifold 3a Positive Diameter 3b Negative Negative 4 Polypole Plate 104a, 4c Anode Separator 104b, 4d Cathode Separator 4e1, 4e2 Cylindrical 4ca Anode end separator 4da Anode end separator 4ci Anode side inlet 4cx Anode side outlet 4dx Anode side outlet 5,105 Film electrode composite 105a Outline line 6a Anode insulation plate 6b Cathode insulation plate 7a Positive side end plate 7b Negative side end plate 8 Bolt 9 Nut 10 Insulation 11a Anode gas diffusion layer 11b Anode gas diffusion layer 112 Seal 112a Manifold seal 12b Anode electrode seal 12c Anode electrode seal 12d Anode manifold seal 12e Anode manifold seal 12f Manifold seal Coating part 12ga Anode manifold seal block 12gb Anode manifold seal block 12h1, 12h2, 12h3 Anode 13 Contact line 14 Porous spacer 15a, 15b Resin frame 16a Pressure resistance performance evaluation device 16b Water electrolysis performance evaluation device 17 Nitrogen bomb 18 2-way valve 19 Auto pressure regulator 20 Flow meter 21 Pressure meter 22 Pump 23a Anode side air / liquid separation device 23b Anode side air / liquid separation device 24a Anode diluting device 24b Anode diluting device 25 Power supply device 25a Current meter 25b Voltage meter 26 Exhaust port η1 Header area 31 First gap 32 Second gap 33, 34, 35 Flow path 40 Anode side sealing part 50 Anode side sealing part 51 Sealing member 60 Single cell 71, 72 Through hole

Claims (6)

Anode separator with high potential resistance and
A hydrogen-resistant cathode separator facing the anode separator and spaced apart from the anode separator.
A membrane electrode complex having an electrolyte membrane and electrodes provided on both sides of the electrolyte membrane, respectively, and arranged between the anode separator and the cathode separator.
An anode inlet manifold, an anode outlet manifold, and a cathode manifold provided independently of each other on the outside of the membrane electrode composite in a direction intersecting the arrangement direction of the anode separator, the cathode separator, and the membrane electrode composite.
Equipped with
Each of the anode separator and the cathode separator
A central portion facing the membrane electrode complex in the arrangement direction,
The outer peripheral portion of the central portion arranged outside in the direction intersecting the arrangement direction, and the outer peripheral portion.
Have,
The anode separator is
An anode provided in the central portion of the anode separator, penetrating the central portion of the anode separator in the arrangement direction, and communicating with the anode inlet manifold and the first gap between the anode separator and the membrane electrode composite. Side entrance and
An anode side outlet provided in the central portion of the anode separator, penetrating the central portion of the anode separator in the arrangement direction, and communicating with the first gap and the anode outlet manifold.
Have,
The cathode separator is
It is provided in the central portion of the cathode separator, penetrates the central portion of the cathode separator in the arrangement direction, and is a gap between the membrane electrode composite and the cathode separator. It has a cathode side outlet that communicates with the second gap partitioned from one gap and the cathode manifold.
It further includes an anode-side sealing portion that constitutes the anode inlet manifold and the anode-outlet manifold together with the anode separator, and a cathode-side sealing portion that constitutes the cathode manifold together with the cathode separator.
Water electrolysis stack. The cathode separator is made of a material containing carbon.
The water electrolysis stack according to claim 1. The anode-side sealing portion has an anode manifold seal disposed on the outer peripheral portion of the anode separator.
It is further provided with an anode-side support wall provided on the outside of the anode manifold seal in a direction intersecting the arrangement direction and supporting the anode manifold seal.
The water electrolysis stack according to claim 1 or 2. The cathode side sealing portion has a cathode manifold seal arranged on the outer peripheral portion of the cathode separator.
Further provided is a cathode side support wall provided on the outside of the cathode manifold seal in a direction intersecting the arrangement direction and supporting the cathode manifold seal.
The water electrolysis stack according to any one of claims 1 to 3. The anode-side sealing portion has an anode manifold seal disposed on the outer peripheral portion of the anode separator.
The anode manifold seal is composed of a resin block extending along the arrangement direction and an O-ring that seals between the resin block and the anode separator 4c.
The water electrolysis stack according to any one of claims 1 to 4. The cathode side sealing portion has a cathode manifold seal arranged on the outer peripheral portion of the cathode separator.
The cathode manifold seal is composed of a resin block extending along the arrangement direction and an auring that seals between the resin block and the cathode separator 4d.
The water electrolysis stack according to any one of claims 1 to 5.

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