WO2023054576A1 - Electrolytic cell - Google Patents

Abstract

An alkali water electrolytic cell comprising: a first frame that is provided with a conductive first partition wall and a first flange part having a first gasket contact surface, and that demarcates an anode chamber; a second frame provided with a conductive second partition wall and a second flange part, and demarcating a cathode chamber; a diaphragm arranged between the first frame body and the second frame body, and demarcating the anode chamber and the cathode chamber; a gasket sandwiched between the first flange part and the second flange part, and holding the diaphragm; an anode arranged inside the anode chamber; and a cathode arranged inside the cathode chamber. The gasket comprises a first and a second gasket element, the first frame is provided with a first nickel-plated layer having a thickness of 27 μm or greater and provided exposed to the first gasket contact surface, and the surface roughness of the first gasket contact surface is 10 μm or less, as the arithmetic mean roughness Ra.

Description

electrolytic cell

The present invention relates to an electrolytic cell for alkaline water electrolysis.

Alkaline water electrolysis is known as a method for producing hydrogen gas and oxygen gas. In the alkaline water electrolysis method, a basic aqueous solution (alkaline water) in which an alkali metal hydroxide (e.g., NaOH, KOH, etc.) is dissolved is used as an electrolytic solution to electrolyze water to generate hydrogen gas from the cathode. Then, oxygen gas is generated from the anode. As an electrolytic cell for alkaline water electrolysis, an electrolytic cell is known which is provided with an anode chamber and a cathode chamber separated by an ion-permeable diaphragm, in which the anode is arranged in the anode chamber and the cathode is arranged in the cathode chamber. The properties of the respective electrode liquids in the anode chamber and the cathode chamber of the alkaline water electrolytic cell are in the strong alkaline range.

JP 2019-99845 A WO2019/111832 WO2019/188260 WO2019/188261 WO2021/085334 WO2013/191140 JP 2016-094650 A JP-A-57-137486 JP-A-1-119687 Japanese Patent No. 6404685 Japanese Patent No. 6621970 WO2015/064644

The inventors of the present invention have found that an electrolytic cell that can be suitably used for the electrolysis of alkaline water, particularly the electrolysis of alkaline water under pressurized conditions, "constitutes a first electrode chamber and has a first flange portion on the outer peripheral portion. a second electrolytic element forming a second pole chamber and having a second flange portion on an outer peripheral portion; the first flange portion and the second flange portion; and a diaphragm separating the first pole chamber and the second pole chamber, wherein the first flange portion is connected to the second flange a first end face facing a portion and in contact with the gasket; and the second flange portion has a second end face facing the first end face of the first flange portion and in contact with the gasket. wherein the gasket is sandwiched between the first end surface and the second end surface, and the first flange portion is in contact with the outer peripheral portion of the gasket from the outer peripheral side of the gasket. wherein the gasket retainer extends toward the second electrolytic element in the stacking direction of the first electrolytic element and the second electrolytic element, protruding from the first end face, The second flange portion has a receding portion receding from the second end face toward the side opposite to the first electrolytic element in the stacking direction at the outer peripheral portion of the second flange portion. and the recessed portion is formed so as to be able to receive at least a part of the gasket pressing portion”, and filed a patent application (Patent Document 1). Patent Literature 1 describes that a rigid material having alkali resistance, such as iron, nickel, or stainless steel, is used as a material for each flange portion.

From the standpoint of alkali resistance and conductivity, nickel is considered to be the most preferable material for the conductive partition walls and flanges that make up each electrode chamber. However, the use of nickel components increases the cost of the electrolytic cell. From the viewpoint of cost reduction of the electrolytic cell, it is preferable to use an inexpensive metal material such as carbon steel (for example, mild steel) for the structural members of the electrolytic cell. However, as a result of further investigation by the present inventors, it has been found that, in an alkaline water electrolyzer in which an inexpensive metal material such as carbon steel is used for the flange portion, the electrolyte and the gas are interspersed particularly between the flange portion on the anode chamber side and the gasket. It has been found that the sealing performance of is likely to deteriorate. It was difficult to solve this problem simply by providing a nickel plating layer on the surface of the flange portion.

An object of the present invention is to provide an alkaline water electrolytic cell capable of suppressing deterioration of the sealability of the anolyte and the anode chamber gas.

The present invention includes the following forms [1] to [14].
[1] a first frame, which includes a conductive first partition and a first flange provided on the outer peripheral portion of the first partition, defining an anode chamber;
a second frame comprising a conductive second partition and a second flange portion provided on the outer peripheral portion of the second partition and defining a cathode chamber;
an ion-permeable diaphragm disposed between the first frame and the second frame to separate the anode chamber and the cathode chamber;
a gasket sandwiched between a first flange portion of the first frame and a second flange portion of the second frame to hold the diaphragm;
an anode disposed in the anode chamber and electrically connected to the first partition;
a cathode disposed in the cathode chamber and electrically connected to the second partition;
with
The gasket is
a first gasket element contacting the first flange portion and the diaphragm;
a second gasket element contacting the second flange and the diaphragm;
the first flange portion comprises a first gasket contact surface in contact with the first gasket element;
The first frame includes a first nickel-plated layer having a thickness of 27 μm or more, which is exposed on the first gasket contact surface of the first flange,
The alkaline water electrolytic bath, wherein the surface roughness of the first gasket contact surface is 10 µm or less as an arithmetic mean roughness Ra.

[2] The alkaline water electrolytic cell according to [1], wherein the surface roughness of the first gasket contact surface is 40 µm or less as the maximum height Rz.

[3] The alkaline water electrolytic bath according to [1] or [2], wherein the first nickel plating layer is an electroless nickel plating layer.

[4] The first frame is
at least one steel first core;
The alkaline water electrolytic cell according to any one of [1] to [3], further comprising the first nickel plating layer provided on the surface of the first core material.

[5] The first nickel plating layer is continuously provided on the first gasket contact surface and the surface of the first frame facing the anode chamber, [1]- The alkaline water electrolytic cell according to any one of [4].

[6] The alkaline water electrolytic cell according to any one of [1] to [5], wherein the first nickel plating layer has a thickness of 30 to 100 μm.

[7] The first frame,
The alkaline water electrolytic cell according to any one of [1] to [6], further comprising a conductive support member that protrudes from the first partition into the anode chamber and supports the anode.

[8] the second flange includes a second gasket contact surface that contacts the second gasket element;
The second frame includes a second nickel-plated layer having a thickness of 27 μm or more, which is exposed on the second gasket contact surface of the second flange,
The alkaline water electrolytic cell according to any one of [1] to [7], wherein the surface roughness of the second gasket contact surface is 10 μm or less as arithmetic mean roughness Ra.

[9] The alkaline water electrolytic cell according to [8], wherein the surface roughness of the second gasket contact surface is 40 µm or less as the maximum height Rz.

[10] The alkaline water electrolytic bath according to [8] or [9], wherein the second nickel plating layer is an electroless nickel plating layer.

[11] The second frame is
at least one steel second core;
The alkaline water electrolytic cell according to any one of [8] to [10], further comprising the second nickel plating layer provided on the surface of the second core material.

[12] The second nickel plating layer is continuously provided on the second gasket contact surface and the surface of the second frame facing the cathode chamber, [8]- The alkaline water electrolytic bath according to any one of [11].

[13] The alkaline water electrolytic cell according to any one of [8] to [12], wherein the second nickel plating layer has a thickness of 50 to 100 μm.

[14] The second frame,
The alkaline water electrolytic cell according to any one of [1] to [13], further comprising a conductive support member that protrudes from the second partition into the cathode chamber and supports the cathode.

According to the alkaline water electrolytic cell of the present invention, the first frame defining the anode chamber has a nickel plating layer with a thickness of 27 μm or more exposed on the gasket contact surface of the flange, and the gasket contact When the surface roughness of the surface is 10 μm or less in terms of arithmetic mean roughness Ra, it is possible to suppress the deterioration of the sealing performance of the anode liquid and the anode chamber gas.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which illustrates typically the electrolytic cell 100 which concerns on embodiment of 1 of this invention. It is the figure which extracted the 1st frame 10 from FIG. It is the figure which extracted the 2nd frame 20 from FIG. FIG. 4 is a cross-sectional view schematically explaining an electrolytic cell 200 according to another embodiment of the present invention; It is the figure which extracted the 3rd frame 210 from FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to these forms. The drawings do not necessarily reflect exact dimensions. Also, in the drawings, some symbols may be omitted. In this specification, unless otherwise specified, the notation "A to B" for numerical values A and B means "A or more and B or less". If a unit is attached only to the numerical value B in such notation, the unit is applied to the numerical value A as well. Also, the terms "or" and "or" shall mean logical sum unless otherwise specified. In addition, the notation " _E1 and/or _E2 " for the elements _E1 and _E2 means " _E1 or _E2 , or a combination thereof", and the elements _E1 , ..., _EN (N is 3 above integers), the notation "E ₁ , ..., E _N-1 , and/or E _N " shall mean "E ₁ , ..., E _N-1 , or E _N , or combinations thereof." do.

FIG. 1 is a cross-sectional view schematically explaining an electrolytic cell 100 according to one embodiment of the present invention. The electrolytic cell 100 is an electrolytic cell for alkaline water electrolysis. As shown in FIG. 1, the electrolytic cell 100 includes a first frame 10 that defines an anode chamber A; a second frame 20 that defines a cathode chamber C; an ion-permeable diaphragm 40 disposed between the second frame 20 and separating the anode chamber A and the cathode chamber C; sandwiched between the first frame 10 and the second frame 20, and a diaphragm an electrically insulating gasket 30 holding the peripheral edge of 40; an anode 50 located in anode chamber A and electrically connected to first partition 11; and a cathode 60 electrically connected to the partition wall 21 . The first frame 10 has a conductive first partition 11 and a first flange portion 12 provided on the outer peripheral portion of the partition 11 . The second frame 20 also has a conductive second partition 21 and a second flange portion 22 provided on the outer peripheral portion of the partition 21 . The partition walls 11 and 21 partition the adjacent electrolytic cells and electrically connect the adjacent electrolytic cells in series. The gasket 30 comprises a first gasket element 31 contacting the first flange portion 12 and the diaphragm 40 and a second gasket element 32 contacting the second flange portion 22 and the diaphragm 40 . The first flange portion 12 together with the diaphragm 11, the diaphragm 40 and the gasket element 31 defines the anode chamber A and the second flange portion 22 together with the diaphragm 21, the diaphragm 40 and the gasket element 32 defines the cathode chamber C. do.

The first frame 10 further includes at least one conductive support member (first support member) 13, 13, . ), and the anode 50 is held by the support member 13 . The support member 13 is electrically connected with the first partition 11 and the anode 50 . The second frame 20 further includes conductive support members (second support members) 23, 23, . In addition, the cathode 60 is held by the support member 23 . The support member 23 is electrically connected with the second partition 21 and the cathode 60 . Although not shown in FIG. 1, the first flange portion 12 includes an anolyte supply channel for supplying the anolyte to the anode chamber A, and an anolyte for recovering the anolyte from the anolyte A and the gas generated at the anode. and a recovery channel. The second flange portion 22 has a catholyte supply channel for supplying the catholyte to the cathode chamber C and a catholyte recovery channel for recovering the catholyte from the cathode chamber C and the gas generated at the cathode.

As a material for the first partition 11 and the second partition 21, a rigid conductive material having alkali resistance can be used. For example, single metals such as nickel and iron; steel.), carbon steel such as high carbon steel, steel such as stainless steel (for example, SUS304, SUS310, SUS310S, SUS316, SUS316L, etc.). Steel materials such as steel and stainless steel can be particularly preferably employed.
As the material of the first flange portion 12, a rigid material having alkali resistance can be used, for example, single metals such as nickel and iron; Metal materials such as carbon steel, stainless steel (for example, SUS304, SUS310, SUS310S, SUS316, SUS316L, etc.), and the like can be preferably employed. In addition to cost reduction and strength, the problem of deterioration in the sealing performance of the electrolyte and gas between the gasket and the gasket described above is likely to occur, and the effect of the present invention to prevent this is likely to be exhibited more remarkably. Steel materials such as carbon steel and stainless steel are particularly preferable, and carbon steel is most preferable.
As the material of the second flange portion 22, a rigid material having alkali resistance can be used. For example, single metals such as nickel and iron; In addition to metal materials such as carbon steel, stainless steel (for example, SUS304, SUS310, SUS310S, SUS316, SUS316L, etc.), non-metal materials such as reinforced plastics can also be used, from the viewpoint of cost reduction and strength. Steel materials such as carbon steel, stainless steel, etc. can be particularly preferably employed.
The partition wall 11 and the flange portion 12 of the first frame 10 may be joined by welding, adhesion, or the like, or may be integrally formed of the same material. Similarly, the partition wall 21 and the flange portion 22 of the second frame 20 may be joined by welding, adhesion, or the like, or may be integrally formed of the same material. However, it is preferable that the partition wall 11 and the flange portion 12 of the first frame 10 are integrally formed of the same material because it is easy to increase the resistance to the pressure inside the pole chamber. It is preferable that the partition wall 21 and the flange portion 22 of the frame 20 are integrally formed of the same material.

As the first support member 13 and the second support member 23, a support member that can be used as a conductive rib in an alkaline water electrolytic bath can be used. In the electrolytic cell 100, the first support member 13 is erected from the partition wall 11 of the first frame 10, and the second support member 23 is erected from the partition wall 21 of the second frame 20. . As long as the first support members 13 can fix and hold the anode 50 to the first frame 10, the connection method, shape, number, and arrangement of the first support members 13 are not particularly limited. As long as the second support members 23 can fix and hold the cathode 60 to the second frame 20, the connection method, shape, number and arrangement of the second support members 23 are not particularly limited.
As the material of the first support member 13 and the second support member 23, a rigid conductive material having alkali resistance can be used. For example, simple metals such as nickel and iron; Metal materials such as medium carbon steel, carbon steel such as high carbon steel, stainless steel (e.g., SUS304, SUS310, SUS310S, SUS316, SUS316L, etc.) can be preferably employed, and from the viewpoint of cost reduction and strength, Steel materials such as carbon steel and stainless steel can be particularly preferably employed.

Simply providing a nickel plating layer on the gasket contact surface of the flange on the anode chamber side of the alkaline water electrolyzer will cause nickel corrosion on the gasket contact surface of the flange, resulting in a decrease in sealing performance between the anolyte and the anode chamber gas. The inventor considers the reason why this cannot be prevented as follows. The polarities of the respective electrode liquids in the anode and cathode compartments of the alkaline water electrolytic cell are in the strongly alkaline range. Such alkaline water exhibits corrosiveness to base metals such as iron, with the reduction reaction of dissolved oxygen gas (O ₂ ) as the cathode (positive electrode of local battery) reaction. The gasket contact surface of the flange normally looks sufficiently smooth to the naked eye, but microscopically, unevenness remains. It is thought that a fine tunnel-like flow path is formed between them, through which alkaline water can enter. When alkaline water enters between the gasket contact surface of the metal flange portion and the gasket, it can corrode (ionize) the metal of the gasket contact surface. Fine pockets are generated where metal corrosion occurs, and alkaline water flows into these pockets through the existing fine tunnel-shaped flow paths to expand the metal corrosion, resulting in fine tunnel-shaped flow paths. a vicious circle of growing and/or developing. When this tunnel-like flow path is sufficiently developed, it becomes possible for alkaline water and, in the case of a large amount, gas to permeate up to the outer periphery of the gasket contact surface of the flange, and the electrolyte and gas sealing performance decreases. It is thought that

　Nickel has sufficient corrosion resistance against alkaline water. Therefore, even if the flange portion is made of a base metal such as iron (for example, carbon steel), if the gasket contact surface of the flange portion is nickel-plated, the gasket of the flange portion will Fine unevenness remains on the contact surface, and even if a fine tunnel is formed between the gasket and the gasket, the expansion of metal corrosion due to alkaline water is avoided, so the electrolyte and gas sealing performance is maintained. is considered to be For that purpose, a thickness of 2 to 10 μm is sufficient for the nickel plating layer, and it is simply uneconomical to provide a nickel plating layer thicker than this. However, in the anode compartment of an alkaline water electrolyzer, the metal flange is exposed to an oxidizing potential and the generation of large amounts of oxygen gas can be a problem.

In particular, the gas generated in the cathode chamber of the alkaline water electrolysis cell is hydrogen gas, and the cathode chamber is filled with a reducing atmosphere, whereas the gas generated in the anode chamber is oxygen gas, and the anode chamber is filled with an oxidizing atmosphere. While being filled with the atmosphere, oxygen gas also dissolves in the anolyte to a saturation level. In the vicinity of the oxygen evolution reaction potential, the oxidation reaction of nickel metal progresses thermodynamically (formula (1) or (2) below). Nickel (II) hydroxide is stable in an alkaline aqueous solution under non-oxidizing conditions, but depending on conditions such as potential and oxygen gas activity, oxidation of nickel may proceed further (for example, the following formulas (3) to (6)).
Ni+2OH ⁻ →Ni(OH) ₂ +2e ⁻ (1)
Ni+(1/2)O ₂ +H ₂ O→Ni(OH) ₂ (2)
Ni(OH) ₂ +OH ⁻ →NiOOH+H ₂ O+e ⁻ (3)
2Ni(OH) ₂₊ (1/2) _O2- >2NiOOH+ _H2O (4)
NiOOH+OH ⁻ →NiO ₂ +H ₂ O+e ⁻ (5)
2NiOOH+(1/2) _O2 → _2NiO2 + _H2O (6)
Such an oxidation reaction of nickel proceeds mainly on the surface of nickel and its vicinity. In general, at the oxide film/atmosphere gas interface, the dissociation pressure of oxygen from the oxide will be equal to the oxygen partial pressure of the atmosphere if the gas flow is sufficient. If the oxygen partial pressure of the atmosphere is higher than the dissociation pressure, the metal will be oxidized; if it is below the dissociation pressure, the oxide will be reduced. An oxygen partial pressure gradient occurs in the oxide film, and the partial pressure decreases as the depth of the oxide film increases. Assuming that the metal/oxide interface is in thermodynamic equilibrium, the system can be regarded as an equilibrium state in which the metal and the oxide coexist, so the oxygen partial pressure is equal to the dissociation pressure. Therefore, it is considered that the higher the activity of oxygen gas in the phase in contact with the oxide film, the more the metal/oxide equilibrium is tilted toward the oxide side and the thicker the oxide film. Since these nickel oxidation reactions are reversible reactions, a reverse reaction (reduction reaction) of the nickel oxidation reaction can proceed when the operation of the alkaline water electrolytic cell is stopped. A decrease in oxygen gas activity in the anode chamber due to recovery of oxygen gas from the anode chamber is also believed to promote the reverse reaction. Nickel oxidation reactions and their reverse reactions at and near the nickel surface can lead to localized stress changes at and near the nickel surface through changes in the crystal structure. Repeated oxidation of nickel and its reverse reaction on and near the surface of nickel can promote deterioration of the nickel plating film through repeated local stress changes. This problem can be particularly pronounced under conditions where the alkaline water electrolyzer is frequently turned on and off. Examples of such operating conditions include unstable power sources such as renewable energy sources (e.g., solar power generation, wind power generation, tidal power generation, etc.) as current sources for alkaline water electrolyzers, and stable power sources such as secondary batteries. The case where it is used without being modified can be mentioned. When the nickel plating film deteriorates, the unevenness of the surface also develops, which is thought to ultimately reduce the electrolyte and gas sealing performance between the flange portion and the gasket.

The present inventor provided a nickel plating layer having a thickness of 27 μm or more so as to be exposed on the gasket contact surface of the flange portion on the anode chamber side, and set the surface roughness of the gasket contact surface to an arithmetic mean roughness Ra of 10 μm. It has been found that the deterioration of sealing performance against the electrolytic solution and the gas can be suppressed even under severe conditions for metal corrosion on the anode chamber side of the alkaline water electrolytic cell by the following.

FIG. 2 is a diagram of only the first frame 10 extracted from FIG. In FIG. 2, elements that have already appeared in FIG. 1 are denoted by the same reference numerals as those in FIG. 1, and description thereof may be omitted. The first flange portion 12 has a first gasket contact surface 12e that contacts the first gasket element 31 (see FIG. 1). The first frame 10 has a first nickel plating layer 14 exposed on the first gasket contact surface 12 e of the first flange portion 12 . The thickness of the first nickel plating layer 14 at the first gasket contact surface 12e is determined from the viewpoint of suppressing deterioration of the sealing performance of the anolyte and the anode chamber gas, and from the viewpoint of resistance to alkaline water with high oxygen gas activity. From the viewpoint of increasing corrosiveness over a long period of time, it is 27 μm or more, more preferably 30 μm or more. Although the upper limit of the thickness is not particularly limited, it may be, for example, 100 μm or less from the viewpoint of manufacturing cost.

From the viewpoint of suppressing the deterioration of the sealing performance of the anolyte and the anode chamber gas, and from the viewpoint of increasing the corrosion resistance in alkaline water with high oxygen gas activity over a long period of time, the surface roughness of the first gasket contact surface 12e is , the arithmetic mean roughness Ra specified in JIS B0601 is 10 μm or less, preferably 9 μm or less, or 8 μm or less. The lower limit of the arithmetic mean roughness Ra is not particularly limited, but in one embodiment, it may be 1 μm or more, or 2 μm or more from the viewpoint of gasket fixation stability and manufacturing cost. In one embodiment, the arithmetic mean roughness Ra can be 1-10 μm, or 1-9 μm, or 1-8 μm.

From the viewpoint of further suppressing the deterioration of the sealing performance of the anolyte and the anode chamber gas, and from the viewpoint of further increasing the corrosion resistance in alkaline water with high oxygen gas activity, the surface roughness of the first gasket contact surface 12e is , the maximum height Rz specified in JIS B0601 is preferably 40 μm or less, more preferably 35 μm or less. Although the lower limit of the maximum height Rz is not particularly limited, it may be 2 μm or more, 4 μm or more, 6 μm or more, or 8 μm or more from the viewpoint of manufacturing cost in one embodiment. In one embodiment, the maximum height Rz can be 2-40 μm, or 4-40 μm, or 6-40 μm.

In the electrolytic cell 100, the first nickel plating layer 14 is continuously provided on the first gasket contact surface 12e and the surface of the first frame 10 facing the anode chamber A. By providing such a thick nickel plating layer also on the surface of the first frame 10 facing the anode chamber A, the corrosion resistance in the oxygen gas atmosphere of the anode chamber and in the oxygen gas saturated alkaline water is improved for long-term use. It becomes possible to raise it to a sufficient level at low cost. From the viewpoint of further enhancing the corrosion resistance in the oxygen gas atmosphere of the anode chamber and in the oxygen gas saturated alkaline water, the thickness of the nickel plating layer on the surface facing the anode chamber A of the first frame 10 is preferably 27 μm. Above, more preferably 30 μm or more, particularly preferably 50 μm or more. Although the upper limit of the thickness of the nickel plating layer on the surface of the first frame 10 facing the anode chamber A is not particularly limited, it may preferably be, for example, 100 μm or less from the viewpoint of cost. The nickel plating layer on the surface of the first frame 10 facing the anode chamber A may be provided on the entire surface of the first frame 10 facing the anode chamber A, or may be provided only on the liquid contact portion. may have been

In one preferred embodiment, the first frame 10 includes at least one steel core 10a and a first nickel plating layer 14 provided on the surface of the core 10a. In the electrolytic cell 100, the steel core 10a includes a steel core 11a forming the partition wall 11, a steel core 12a forming the flange portion 12, and a steel core forming the support member 13. material 13a. The first nickel plating layer 14 is provided so as to be exposed at least on the gasket contact surface 12e of the flange portion 12, and continuously from the first gasket contact surface 12e, on the surface of the core material 10a facing the anode chamber. It may be provided on the entire surface, or may be provided on the entire surface of the core material 10a.

In one embodiment, such a first frame 10 is manufactured by nickel-plating a steel core 11a forming the partition wall 11 and a steel core 12a forming the flange 12. be able to. An integrated core material including the steel core material 11a that constitutes the partition wall 11 and the steel core material 12a that constitutes the flange portion 12 may be plated with nickel. 11a and the steel core material 12a forming the flange portion 12 may be separately plated with nickel and then joined together. When the first frame 10 includes the support member 13, the steel core member 11a forming the partition wall 11 and the steel core member 13a forming the support member 13 are included, and optionally the flange portion 12 is provided. Nickel plating may be applied to the integrated core material further including the steel core material 12a constituting the support member 13, and the steel core material 13a constituting the support member 13 is separately nickel-plated, and then the core material 13a and the nickel metal are plated separately. A support member 13 including a plating layer may be joined to the partition wall 11 . As described above, the first flange portion 12 includes an anolyte supply channel (not shown) that supplies the anolyte to the anode chamber A, and an anolyte recovery path that recovers the anolyte from the anolyte A and the gas generated at the anode. and a channel (not shown). In the case where the flange portion 12 has a core material 12 a made of steel, it is preferable that the nickel plating layer 14 is also provided on the inner surfaces of the anolyte supply channel and the anolyte recovery channel provided in the flange portion 12 . The nickel plating layer 14 is preferably provided on at least the liquid-contacting portions of the inner surfaces of the anolyte supply channel and the anolyte recovery channel provided in the flange portion 12, and may be provided on the entire inner surface. .

FIG. 3 is a diagram of only the second frame 20 extracted from FIG. In FIG. 3, elements that have already appeared in FIGS. 1 and 2 are assigned the same reference numerals as those in FIGS. 1 and 2, and description thereof may be omitted. The second flange portion 22 has a second gasket contact surface 22e that contacts the second gasket element 32 (see FIG. 1). The second frame 20 includes a second nickel plating layer 24 exposed on the second gasket contact surface 22 e of the second flange portion 22 . The thickness of the second nickel plating layer 24 at the second gasket contact surface 22e is preferably 27 μm or more, more preferably 30 μm or more, from the viewpoint of suppressing deterioration of the sealing performance of the catholyte and the cathode chamber gas. . Although the upper limit of the thickness is not particularly limited, it may be, for example, 100 μm or less from the viewpoint of manufacturing cost.

From the viewpoint of suppressing the deterioration of the sealing performance of the catholyte and the cathode chamber gas, the surface roughness of the second gasket contact surface 22e is preferably 10 μm or less, more preferably 10 μm or less as the arithmetic mean roughness Ra specified in JIS B0601. is 9 μm or less, or 8 μm or less. The lower limit of the arithmetic mean roughness Ra is not particularly limited, but in one embodiment, it may be 1 μm or more, or 2 μm or more from the viewpoint of gasket fixation stability and manufacturing cost. In one embodiment, the arithmetic mean roughness Ra can be 1-10 μm, or 1-9 μm, or 1-8 μm.

From the viewpoint of further suppressing the deterioration of the sealing properties of the catholyte and the cathode chamber gas, the surface roughness of the second gasket contact surface 22e is preferably 40 μm or less, more preferably 40 μm or less, more preferably 35 μm or less. Although the lower limit of the maximum height Rz is not particularly limited, it may be 2 μm or more, 4 μm or more, 6 μm or more, or 8 μm or more from the viewpoint of manufacturing cost in one embodiment. In one embodiment, the maximum height Rz can be 2-40 μm, or 4-40 μm, or 6-40 μm.

In the electrolytic cell 100, the second nickel plating layer 24 is continuously provided on the second gasket contact surface 22e and the surface of the second frame 20 facing the cathode chamber C. By providing a nickel plating layer also on the surface of the second frame 20 facing the cathode chamber C, it is possible to raise the corrosion resistance of the cathode chamber under alkaline conditions to a sufficient level. On the surface of the second frame 20 facing the cathode chamber C, the nickel plating layer has a thickness that provides corrosion resistance that can withstand the alkaline conditions of the cathode chamber. A thickness of 2 μm may be sufficient, preferably 10 μm or more, more preferably 27 μm or more, and in one embodiment 30 μm or more. Although the upper limit of the thickness of the nickel plating layer on the surface of the second frame 20 facing the cathode chamber C is not particularly limited, it is preferably 100 μm or less from the viewpoint of cost. The nickel-plated layer on the surface of the second frame 20 facing the cathode chamber C may be provided on the entire surface of the second frame 20 facing the cathode chamber C, or may be provided only on the wetted portion. may have been

In one preferred embodiment, the second frame 20 includes at least one steel core 20a and a second nickel plating layer 24 provided on the surface of the core 20a. In the electrolytic cell 100, the steel core 20a includes a steel core 21a forming the partition wall 21, a steel core 22a forming the flange portion 22, and a steel core forming the support member 23. material 23a. The second nickel plating layer 24 is provided so as to be exposed at least on the gasket contact surface 22e of the flange portion 22, and continuously from the second gasket contact surface 22e on the surface of the core material 20a facing the cathode chamber. It may be provided over the entire surface of the core material 20a.

In one embodiment, such a second frame 20 is manufactured by nickel-plating a steel core 21a forming the partition wall 21 and a steel core 22a forming the flange 22. be able to. An integrated core material including a steel core material 21a constituting the partition wall 21 and a steel core material 22a constituting the flange portion 22 may be plated with nickel. 21a and the steel core material 22a forming the flange portion 22 may be individually plated with nickel and then joined together. When the second frame body 20 includes the support member 23, the steel core member 21a forming the partition wall 21 and the steel core member 23a forming the support member 23 are included, and optionally the flange portion 22 is provided. Nickel plating may be applied to the integrated core material further including the steel core material 22a constituting the support member 23, and the steel core material 23a constituting the support member 23 is separately nickel-plated, and then the core material 23a and the nickel metal are plated separately. A support member 23 including a plating layer may be joined to the partition wall 21 . As described above, the second flange portion 22 also includes a catholyte supply channel (not shown) that supplies the catholyte to the cathode chamber C, and a cathode for recovering the catholyte and the gas generated at the cathode from the cathode chamber C. and a liquid recovery channel (not shown). When the flange portion 22 has a steel core 22a, the inner surfaces of the catholyte supply channel and the catholyte recovery channel provided in the flange portion 22 are preferably provided with the nickel plating layer 24 as well. The nickel plating layer 24 is preferably provided on at least the liquid-contacting portion of the inner surfaces of the catholyte supply channel and the catholyte recovery channel provided in the flange portion 22, and may be provided on the entire inner surface. .

In another embodiment, the second frame 20 is formed by nickel-plating a steel core 21a that constitutes the partition 21, and then combining the partition 21 with the core 21a and the nickel-plated layer and the non-metallic material. It can be manufactured by joining the flange portion 22 configured with. When the second frame 20 is provided with the support member 23, the integrated core material including the steel core material 21a constituting the partition wall 21 and the steel core material 23a constituting the support member 23 is plated with nickel. Alternatively, the steel core 21a forming the partition wall 21 and the steel core 23a forming the support member 23 may be separately plated with nickel and then joined together.

A known nickel plating method can be used to provide the first nickel plating layer 14 on the first frame 10 . Nickel plating on the metallic core material may be performed by electroplating or by electroless plating. However, while electrolytic plating generally results in a rough surface, electroless plating tends to obtain a surface that satisfies the above arithmetic mean roughness Ra in the present invention. Therefore, electroless nickel plating can be preferably used from the viewpoints of suppressing the deterioration of the sealing performance between the anolyte and the anode chamber gas and from the viewpoint of enhancing corrosion resistance in alkaline water with high oxygen gas activity. Electroless nickel plating can be performed by known processes. For example, by performing the pickling treatment step, the degreasing treatment step, the electrolytic degreasing treatment step, the acid activation step, the electroless nickel plating deposition step, and the post-plating heat treatment step on the metal core material in the above order, the metal An electroless nickel plating layer can be formed on the surface of the core material. The electroless nickel plating may be electroless nickel-phosphorus plating or electroless nickel-boron plating. Electroless nickel-phosphorus plating is preferred from the viewpoint of further enhancing corrosion resistance in alkaline water with high gas activity. The phosphorus content in the electroless nickel plating layer 14 is usually 1 to 13% by mass, and in one embodiment, 1% by mass or more and less than 5% by mass, or 5% by mass or more and less than 10% by mass, or 10% by mass. It may be more than or equal to 13% by mass or less. From the viewpoint of further suppressing the deterioration of the sealability of the anolyte and the anode chamber gas, and from the viewpoint of further increasing the corrosion resistance in alkaline water with high oxygen gas activity, the phosphorus content in the electroless nickel plating layer 14 is preferably 5 to 13% by mass, and in one embodiment can be 5% by mass or more and less than 10% by mass. In particular, when the first nickel plating layer 14 is provided continuously on the first gasket contact surface 12e and the surface of the first frame 10 facing the anode chamber A, the electrical resistance of the electrolytic cell 100 can be further reduced. From the viewpoint of improving energy efficiency by using the electroless nickel plating layer 14, the phosphorus content in the electroless nickel plating layer 14 is preferably 5% by mass or more and less than 10% by mass.

A known nickel plating method can be used to provide the second nickel plating layer 24 on the second frame 20 . Nickel plating on the metallic core material may be performed by electroplating or by electroless plating. However, electroless nickel plating can be preferably used from the viewpoint of further suppressing the deterioration of the sealing properties of the catholyte and the cathode chamber gas and from the viewpoint of further increasing the corrosion resistance in alkaline water. Electroless nickel plating can be performed by known processes. For example, by performing the pickling treatment step, the degreasing treatment step, the electrolytic degreasing treatment step, the acid activation step, the electroless nickel plating deposition step, and the post-plating heat treatment step on the metal core material in the above order, the metal An electroless nickel plating layer can be formed on the surface of the core material. The electroless nickel plating may be electroless nickel-phosphorus plating or electroless nickel-boron plating. Electroless nickel-phosphorus plating is preferred from the viewpoint of further enhancing corrosion resistance in water. The phosphorus content in the electroless nickel plating layer 24 is usually 1 to 13% by mass, and in one embodiment, 1% by mass or more and less than 5% by mass, or 5% by mass or more and less than 10% by mass, or 10% by mass. It may be more than or equal to 13% by mass or less. From the viewpoint of further suppressing the deterioration of the sealing properties of the catholyte and the cathode chamber gas and from the viewpoint of further increasing the corrosion resistance in alkaline water, the phosphorus content in the electroless nickel plating layer 24 is preferably 5 to 5. 13% by mass, and in one embodiment, it may be 5% by mass or more and less than 10% by mass. In particular, when the second nickel plating layer 24 is provided continuously on the second gasket contact surface 22e and the surface of the second frame 20 facing the anode chamber A, the electrical resistance of the electrolytic cell 100 can be further reduced. From the viewpoint of improving energy efficiency by using the electroless nickel plating layer 24, the phosphorus content in the electroless nickel plating layer 24 is preferably 5% by mass or more and less than 10% by mass.

As the gasket 30 (see FIG. 1), a gasket that can be used in an electrolytic cell for alkaline water electrolysis and has electrical insulation can be used without particular limitation. A cross section of the gasket 30 appears in FIG. The gasket 30 has a flat shape and sandwiches the peripheral portion of the diaphragm 40 while being sandwiched between the first flange portion 12 and the second flange portion 22 . The gasket 30 comprises a first gasket element 31 contacting the first flange portion 12 and the diaphragm 40 and a second gasket element 32 contacting the second flange portion 22 and the diaphragm 40 . In one embodiment, the first gasket element 31 and the second gasket element 32 are separate and distinct gasket elements. In other embodiments, the first gasket element 31 and the second gasket element 32 may be joined at their outer edges to form an integral gasket. Such a one-piece gasket makes it possible to further improve the electrolyte and gas sealing properties. The gasket 30 is preferably made of an elastomer having alkali resistance. Examples of materials for the gasket 30 include natural rubber (NR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), butadiene rubber (BR), acrylonitrile-butadiene rubber (NBR), silicone rubber (SR), ethylene- Elastomers such as propylene rubber (EPT), ethylene-propylene-diene rubber (EPDM), fluororubber (FR), isobutylene-isoprene rubber (IIR), urethane rubber (UR), and chlorosulfonated polyethylene rubber (CSM). can. Moreover, when using a gasket material that does not have alkali resistance, a layer of a material having alkali resistance may be provided by coating or the like on the surface of the gasket material.

As the diaphragm 40, an ion-permeable diaphragm that can be used in an electrolytic cell for alkaline water electrolysis can be used without particular limitation. It is desirable that the diaphragm 40 have low gas permeability, low electrical conductivity, and high strength. Examples of the diaphragm 40 include a porous membrane made of asbestos or modified asbestos, a porous diaphragm using polysulfone-based polymer, a cloth using polyphenylene sulfide fiber, a fluorine-based porous membrane, an inorganic material and an organic material. A porous membrane such as a porous membrane using a hybrid material containing both of In addition to these porous diaphragms, it is also possible to use an ion-exchange membrane such as a fluorine-based membrane as the diaphragm 40 .

As the anode 50, any anode that can be used in an electrolytic cell for alkaline water electrolysis can be used without particular limitation. Anode 50 typically comprises a conductive substrate and a catalyst layer coating the surface of the substrate. The catalyst layer is preferably porous. The conductive substrate of anode 50 can be, for example, nickel, nickel alloys, nickel iron, vanadium, molybdenum, copper, silver, manganese, platinum group elements, graphite, or chromium, or combinations thereof. A conductive base material made of nickel can be preferably used for the anode 50 . The catalyst layer contains nickel as an element. The catalyst layer preferably comprises nickel oxide, nickel metal, or nickel hydroxide, or combinations thereof, and may comprise alloys of nickel with one or more other metals. It is particularly preferred that the catalyst layer consists of metallic nickel. The catalyst layer may further contain chromium, molybdenum, cobalt, tantalum, zirconium, aluminum, zinc, platinum group elements, rare earth elements, or combinations thereof. Rhodium, palladium, iridium, or ruthenium, or a combination thereof, may be further supported on the surface of the catalyst layer as an additional catalyst. The conductive substrate of anode 50 may be a rigid substrate or a flexible substrate. Examples of the rigid conductive base material that constitutes the anode 50 include expanded metal and punched metal. As a flexible conductive base material that constitutes the anode 50, for example, a wire mesh woven (or knitted) with metal wires can be used.

As the cathode 60, a cathode that can be used in an electrolytic cell for alkaline water electrolysis can be used without particular limitation. Cathode 60 typically comprises a conductive substrate and a catalyst layer coating the surface of the substrate. As the conductive base material of the cathode 60, for example, nickel, nickel alloy, stainless steel, mild steel, nickel alloy, or a nickel-plated surface of stainless steel or mild steel can be preferably used. As the catalyst layer of the cathode 60, a catalyst layer made of noble metal oxides, nickel, cobalt, molybdenum, or manganese, oxides thereof, or noble metal oxides can be preferably used. The conductive substrate that constitutes the cathode 60 may be, for example, a rigid substrate or a flexible substrate. Examples of the rigid conductive base material that constitutes the cathode 60 include expanded metal and punched metal. Moreover, as a flexible conductive base material constituting the cathode 60, for example, a wire mesh woven (or knitted) with metal wires can be used.

According to the electrolytic cell 100, the first frame 10 defining the anode chamber A is exposed on the gasket contact surface 12e of the first flange portion 12 and has a thickness of 27 μm or more, more preferably 30 μm or more. The first nickel plating layer 14 is provided, and the surface roughness of the gasket contact surface 12e is 10 μm or less as an arithmetic mean roughness Ra, so that it is possible to suppress the deterioration of the sealing performance of the anolyte and the anode chamber gas. is.

In the above description of the present invention, the electrolytic cell 100 having a configuration in which there are gaps between the anode 50 and the diaphragm 40 and between the cathode 60 and the diaphragm 40 is taken as an example, but the present invention is not limited to this configuration. . For example, instead of the rigid cathode 60, a flexible cathode is provided in the cathode chamber, a cathode current collector held by the support member 23, and a cathode current collector disposed between the cathode current collector and the diaphragm 40. It comprises a supported conductive elastic body and a flexible cathode disposed between the elastic body and the diaphragm 40 , the elastic body pressing the flexible cathode toward the diaphragm 40 and the anode 50 to allow the flexible A so-called zero-gap type alkaline water electrolytic cell, in which the cathode and the diaphragm 40 are in direct contact and the diaphragm 40 and the anode 50 are in direct contact, is also possible.

In the above description of the present invention, the first nickel plating layer 14 is provided continuously on the first gasket contact surface 12e and the surface of the first frame 10 facing the anode chamber A. Although the electrolytic cell 100 is taken as an example, the present invention is not limited to this form. For example, in the first frame 10, the alkaline water electrolytic bath may have a form in which only the first gasket contact surface 12e is provided with a nickel plating layer. Further, for example, the first nickel-plated layer 14 is exposed on the first gasket contact surface 12e, and the third nickel-plated layer that is not continuous with the first nickel-plated layer 14 is provided on the first gasket contact surface 12e. It is also possible to provide an alkaline water electrolytic bath in the form of being provided on the surface of the frame 10 facing the anode chamber A.

In the above description of the present invention, the second nickel plating layer 24 is provided continuously on the second gasket contact surface 22e and the surface of the second frame 20 facing the cathode chamber C. Although the electrolytic cell 100 is taken as an example, the present invention is not limited to this form. For example, in the second frame 20, the alkaline water electrolytic bath may have a form in which only the second gasket contact surface 22e is provided with a nickel plating layer. Further, for example, the second nickel-plated layer 24 is exposed on the second gasket contact surface 22e, and the fourth nickel-plated layer that is not continuous with the second nickel-plated layer 24 is the second nickel-plated layer. It is also possible to provide an alkaline water electrolytic bath in which the surface of the frame facing the anode chamber C is provided.

In the above description of the present invention, the electrolytic cell 100 in which the second frame 20 defining the cathode chamber C is provided with the second nickel plating layer 24 exposed on the second gasket contact surface 22e. Although given as an example, the invention is not limited to this form. For example, an alkaline water electrolytic bath in which the second frame 20 does not have a nickel plating layer on the second gasket contact surface 22e is also possible.

In the above description of the present invention, the electrolytic cell 100 in which the first frame 10 protrudes from the first partition wall 11 into the anode chamber A and includes the conductive support member 13 that supports the anode 50 is taken as an example. , the present invention is not limited to this form. For example, an alkaline water electrolytic bath without the support member 13 may be used. As an example of such an alkaline water electrolytic bath, instead of the conductive support member 13, a first conductive elastic body arranged between the first partition wall 11 and the anode 50 is provided. An alkaline water electrolytic cell in which one conductive elastic body presses the anode 50 from behind toward the diaphragm 40 can be mentioned.

In the above description of the present invention, the electrolytic cell 100 in which the second frame 20 protrudes from the second partition wall 21 into the cathode chamber C and is provided with the conductive support member 23 for supporting the cathode 60 is taken as an example. , the present invention is not limited to this form. For example, an alkaline water electrolytic bath that does not include the support member 23 may be used. As an example of such an alkaline water electrolytic bath, instead of the conductive support member 13, a second conductive elastic body disposed between the second partition wall 21 and the cathode 60 is provided. 2 conductive elastic bodies press the cathode 60 toward the diaphragm 40 from behind.

In the above description of the present invention, the electrolytic bath 100 in the form of a single cell was taken as an example, but the present invention is not limited to this form. For example, an electrolytic cell having a configuration in which a plurality of electrolytic cells each having a set of an anode chamber A defined by the first frame 10 and a cathode chamber C defined by the second frame 20 are connected in series. is also possible. Further, for example, the flange portion 12 of the first frame 10 may also extend to the opposite side of the partition wall 11 (the right side of the paper surface in FIG. 1) to further define the cathode chamber of the adjacent electrolytic cell together with the partition wall 11. Also, the flange portion 22 of the second frame 20 may extend to the opposite side of the partition wall 21 (the left side of the paper surface in FIG. 1) to further define the anode chamber of the adjacent electrolytic cell together with the partition wall 21 . FIG. 4 is a diagram schematically illustrating an alkaline water electrolytic bath 200 (hereinafter sometimes referred to as "electrolytic bath 200") according to such another embodiment. In FIG. 4, elements that have already appeared in FIGS. 1 to 3 are denoted by the same reference numerals as those in FIGS. 1 to 3, and description thereof may be omitted. The electrolytic cell 200 is an alkaline water electrolytic cell having a structure in which an electrolytic cell consisting of an anode chamber A1 and a cathode chamber C1 and an electrolytic cell consisting of an anode chamber A2 and a cathode chamber C2 are connected in series. The electrolytic cell 200 includes a first frame 10 connected to the anode terminal and defining the anode chamber A1; a second frame 20 connected to the cathode terminal and defining the cathode chamber C2; and a first frame. at least one third frame 210 disposed between 10 and the second frame 20; and a plurality of gaskets 30, diaphragms 40, anodes 50, and cathodes 60, respectively. The diaphragm 40 is provided between the first frame 10 and the adjacent third frame 210, between the second frame 20 and the adjacent third frame 210, and When there are a plurality of third frames 210 , they are arranged between two adjacent third frames 210 and sandwiched between gaskets 30 . The first frame 10 and the third frame 210 define the anode chamber A1 and the cathode chamber C1, and the third frame 210 and the second frame 20 define the anode chamber A2 and the cathode chamber C2. It is An anode 50 is arranged in each of the anode chambers A1 and A2, and a cathode 60 is arranged in each of the cathode chambers C1 and C2.

The first frame 10 and the second frame 20 are respectively the first frame 10 (FIG. 2) and the second frame 20 (FIG. 4) in the electrolytic cell 100 (FIG. 1) described above. have the same configuration. The partition 11 of the first frame 10 is connected to the anode terminal, and the partition 21 of the second frame 20 is connected to the cathode terminal. The anode 50 is held by the support member 13 in the anode chamber A1 defined by the first frame 10, and the cathode 20 is held by the support member 23 in the cathode chamber C2 defined by the second frame 20. The points are the same as above.

The third frame 210 is a bipolar electrolytic element having a structure in which the first frame 10 and the second frame 20 are integrated. That is, the third frame 210 includes a conductive partition 211, a first flange portion 212 extending from the outer peripheral portion of the partition 211 toward the second frame 20 (left side of the paper surface of FIG. 4), and a partition 211 and a second flange portion 222 extending toward the first frame 10 (right side of the paper surface of FIG. 4). In the third frame 210, the first flange portion 212 and the second flange portion 222 are integrally formed. In the third frame 210, a conductive support member (second support member) 223 is provided protruding from the partition 211 on the first frame 10 side of the partition 211 (on the right side of the paper surface of FIG. 4). . The support member 223 holds the cathode 60 in the cathode chamber C1 and is electrically connected to the cathode 60 and the partition wall 211 arranged in the cathode chamber C1. In the third frame 210, a conductive support member (first support member) 213 is provided protruding from the partition 211 on the side of the partition 211 toward the second frame 20 (on the left side of the paper surface of FIG. 4). . The support member 213 holds the anode 50 in the anode chamber A2 and is electrically connected to the anode 50 arranged in the anode chamber A2 and the partition wall 211 of the third frame 210 . The configuration of partition wall 211, first support member 213, and second support member 223 is similar to partition wall 11, first support member 13, and second support member 11, described above with respect to electrolytic cell 100 (FIG. 1). Similar to member 23 . The configuration of the first flange portion 212 and the second flange portion 222 is related to the electrolytic cell 100 (FIG. 1), except that the first flange portion 212 and the second flange portion 222 are integrally formed. It is the same as the first flange portion 12 and the second flange portion 22 described above. The first flange portion 212 of the third frame 210 defines the anode chamber A2 together with the partition wall 211, the diaphragm 40, and the first gasket element 31, and the second flange portion of the third frame 210 222 together with diaphragm 211, diaphragm 40 and second gasket element 32 define cathode chamber C1.

FIG. 5 is a diagram of only the third frame 210 extracted from FIG. In FIG. 5, elements that have already appeared in FIGS. 1 to 4 are denoted by the same reference numerals as those in FIGS. 1 to 4, and description thereof may be omitted. The first flange portion 212 of the third frame 210 has a first gasket contact surface 212e that contacts the first gasket element 31 (see FIG. 1). The third frame 210 has a first nickel plating layer 214 exposed on the first gasket contact surface 212 e of the first flange portion 212 . The thickness of the first nickel plating layer 214 at the first gasket contact surface 212e is determined from the viewpoint of suppressing deterioration of the sealing performance of the anolyte and the anode chamber gas, and from the viewpoint of resistance to alkaline water with high oxygen gas activity. From the viewpoint of enhancing corrosiveness over a long period of time, the thickness is 27 μm or more, more preferably 30 μm or more. Although the upper limit of the thickness is not particularly limited, it may be, for example, 100 μm or less from the viewpoint of manufacturing cost.

From the viewpoint of suppressing the deterioration of the sealing performance of the anolyte and the anode chamber gas, and from the viewpoint of increasing the corrosion resistance in alkaline water with high oxygen gas activity over a long period of time, the surface roughness of the first gasket contact surface 212e is , the arithmetic mean roughness Ra specified in JIS B0601 is 10 μm or less, preferably 9 μm or less, or 8 μm or less. The lower limit of the arithmetic mean roughness Ra is not particularly limited, but in one embodiment, it may be 1 μm or more, or 2 μm or more from the viewpoint of gasket fixation stability and manufacturing cost. In one embodiment, the arithmetic mean roughness Ra can be 1-10 μm, or 1-9 μm, or 1-8 μm.

From the viewpoint of further suppressing the deterioration of the sealability of the anolyte and the anode chamber gas, and from the viewpoint of further increasing the corrosion resistance in alkaline water with high oxygen gas activity, the surface roughness of the first gasket contact surface 212e is , the maximum height Rz specified in JIS B0601 is preferably 40 μm or less, more preferably 35 μm or less. Although the lower limit of the maximum height Rz is not particularly limited, it may be 2 μm or more, 4 μm or more, 6 μm or more, or 8 μm or more from the viewpoint of manufacturing cost in one embodiment. In one embodiment, the maximum height Rz can be 2-40 μm, or 4-40 μm, or 6-40 μm.

In the electrolytic cell 200, the first nickel plating layer 214 is continuously provided on the first gasket contact surface 212e and the surface of the third frame 210 facing the anode chamber A2. Since the third frame 210 has such a thick nickel plating layer on the liquid-contacting portion of the anode chamber A2, the corrosion resistance in the oxygen gas atmosphere of the anode chamber and in the oxygen gas-saturated alkaline water is sufficient for long-term use. can be raised to a higher level. From the viewpoint of further enhancing the corrosion resistance in the oxygen gas atmosphere of the anode chamber and in the oxygen gas-saturated alkaline water, the thickness of the nickel plating layer on the surface of the third frame 210 facing the anode chamber A2 is preferably 27 μm. Above, more preferably 30 μm or more, particularly preferably 50 μm or more. Although the upper limit of the thickness of the nickel plating layer on the surface of the third frame 210 facing the anode chamber A2 is not particularly limited, it is preferably 100 μm or less from the viewpoint of cost. The nickel plating layer on the surface of the third frame 210 facing the anode chamber A2 may be provided on the entire surface of the third frame 210 facing the anode chamber A2, or may be provided only on the liquid contact portion. may have been

In one preferred embodiment, the third frame 210 includes at least one steel core 210a and a first nickel plating layer 214 provided on the surface of the core 210a. In the electrolytic cell 200, the steel core material 210a of the third frame 210 constitutes the steel core material 211a constituting the partition wall 211, the first flange portion 212, and the second flange portion 222, respectively. It includes steel cores 212a and 222a, and steel cores 213a and 223a that form the first support member 213 and the second support member 223, respectively. In the third frame 210, the steel core 212a forming the first flange portion 212 and the steel core 222a forming the second flange portion 222 are integrally formed. The first nickel plating layer 214 is provided so as to be exposed at least on the gasket contact surface 212e of the first flange portion 212, and is continuous from the first gasket contact surface 212e to form the anode chamber A2 of the core member 210a. may be provided on the entire surface facing the core member 210a.

The second flange portion 222 of the third frame 210 has a second gasket contact surface 222e that contacts the second gasket element 32 (see FIG. 4). The third frame 210 has a second nickel plating layer 224 exposed on the second gasket contact surface 222 e of the second flange portion 222 . The thickness of the second nickel plating layer 224 at the second gasket contact surface 222e is preferably 27 μm or more, more preferably 30 μm or more, from the viewpoint of suppressing deterioration of the sealing performance of the catholyte and the cathode chamber gas. . Although the upper limit of the thickness is not particularly limited, it may be, for example, 100 μm or less from the viewpoint of manufacturing cost.

From the viewpoint of suppressing the deterioration of the sealing performance of the catholyte and the cathode chamber gas, the surface roughness of the second gasket contact surface 222e is preferably 10 μm or less, more preferably 10 μm or less as the arithmetic mean roughness Ra specified in JIS B0601. is 9 μm or less, or 8 μm or less. The lower limit of the arithmetic mean roughness Ra is not particularly limited, but in one embodiment, it may be 1 μm or more, or 2 μm or more from the viewpoint of gasket fixation stability and manufacturing cost. In one embodiment, the arithmetic mean roughness Ra can be 1-10 μm, or 1-9 μm, or 1-8 μm.

From the viewpoint of further suppressing the deterioration of the sealability of the catholyte and the cathode chamber gas, the surface roughness of the second gasket contact surface 222e is preferably 40 μm or less, more preferably 40 μm or less, more preferably 35 μm or less. Although the lower limit of the maximum height Rz is not particularly limited, it may be 2 μm or more, 4 μm or more, 6 μm or more, or 8 μm or more from the viewpoint of manufacturing cost in one embodiment. In one embodiment, the maximum height Rz can be 2-40 μm, or 4-40 μm, or 6-40 μm.

In the electrolytic cell 200, the second nickel plating layer 224 is continuously provided on the second gasket contact surface 222e and the surface of the third frame 210 facing the cathode chamber C1. By providing a nickel plating layer also on the surface of the third frame body 210 facing the cathode chamber C1, it becomes possible to raise the corrosion resistance of the cathode chamber under alkaline conditions to a sufficient level. On the surface of the third frame 210 facing the cathode chamber C1, the nickel plating layer has a thickness that provides corrosion resistance that can withstand the alkaline conditions of the cathode chamber. A thickness of 2 μm may be sufficient, preferably 10 μm or more, more preferably 27 μm or more, and in one embodiment 30 μm or more. Although the upper limit of the thickness of the nickel plating layer on the surface of the third frame 210 facing the cathode chamber C1 is not particularly limited, it is preferably 100 μm or less from the viewpoint of cost. The nickel plating layer on the surface of the third frame 210 facing the cathode chamber C1 may be provided on the entire surface of the third frame 210 facing the cathode chamber C1, or may be provided only on the wetted portion. may have been

In one preferred embodiment, the third frame body 210 includes at least one steel core material 210a, and the first nickel plating layer 214 and the second nickel plating layer provided on the surface of the core material 210a. and layer 224 . In the electrolytic cell 200, the steel core material 210a of the third frame 210 constitutes the steel core material 211a constituting the partition wall 211, the first flange portion 212, and the second flange portion 222, respectively. It includes steel cores 212a and 222a, and steel cores 213a and 223a that form the first support member 213 and the second support member 223, respectively. In the third frame 210, the steel core 212a forming the first flange portion 212 and the steel core 222a forming the second flange portion 222 are integrally formed. The second nickel plating layer 224 is provided so as to be exposed at least on the gasket contact surface 222e of the second flange portion 222, and further continuously from the second gasket contact surface 222e, the cathode chamber C1 of the core member 210a. may be provided on the entire surface facing the core member 210a.

In one embodiment, such a third frame 210 includes a steel core 211a forming the partition wall 211 and a steel core 212a forming the first flange portion 212, and optionally, It can be manufactured by nickel-plating the steel core material 222 a that constitutes the second flange portion 222 . An integral core material including a steel core 211a forming the partition 211 and steel cores 212a and 222a forming the flanges 212 and 222 may be plated with nickel. The core material 211a made of steel, the steel core material 212a constituting the first flange part 212, and the steel core material 222a constituting the second flange part 222 are individually plated with nickel, and then the two are joined together. May be joined. Further, when the third frame 210 includes the support members 213 and 223, the steel core members 211a and 213a and 223a that form the partition wall 211 and the support members 213 and 223 are included. Nickel plating may be applied to the integrated core material further including the steel core materials 212a and 222a that form the flange portions 212 and 222, and the steel core materials 213a and 223a that form the support members 213 and 223. are separately plated with nickel, and then the first support member 213 including the core material 213a and the nickel plating layer and the second support member 223 including the core material 223a and the nickel plating layer are respectively joined to the partition wall 211. may

Although not shown in FIGS. 4 and 5, in the third frame 210, the flanges 212 and 222 form an anode liquid supply channel (not shown) that supplies the anode liquid to the anode chamber A2 and an anode liquid supply channel (not shown). an anolyte recovery channel (not shown) for recovering the anolyte and the gas generated at the anode from the cathode chamber C1; a catholyte supply channel (not shown) for supplying the catholyte to the cathode chamber C1; A catholyte recovery channel (not shown) for recovering gas generated at the cathode is provided. In the electrolytic cell 200, the anolyte supply channel and the anolyte recovery channel provided in the third frame 210 are connected to the first frame through through holes (not shown) provided in the gasket 30 and the diaphragm 40, respectively. It is in fluid communication with an anolyte supply channel and an anolyte recovery channel provided in the body 10, respectively. The catholyte supply channel and the catholyte recovery channel provided in the third frame 210 are provided in the second frame 20 through through holes (not shown) provided in the gasket 30 and the diaphragm 40, respectively. are in fluid communication with the catholyte supply and return channels, respectively. However, the anolyte supply channel and the anolyte recovery channel are not in fluid communication with the cathode chambers C1 and C2, and no electrolyte or gas flows between them. Also, the catholyte supply channel and the catholyte recovery channel are not in fluid communication with the anode chambers A1 and A2, and there is no electrolyte or gas flow between them. When the flanges 212 and 222 have steel cores 212a and 222a, the nickel plating layer 214 is also provided on the inner surfaces of the anolyte supply channel and the anolyte recovery channel provided in the flanges 212 and 222. Preferably, the nickel plating layer 224 is also provided on the inner surfaces of the catholyte supply channel and the catholyte recovery channel provided in the flange portions 212 and 222 . The nickel plating layer 214 is preferably provided on at least the liquid-contacting portions of the inner surfaces of the anolyte supply channel and the anolyte recovery channel provided in the flange portions 212 and 222, and is provided on the entire inner surfaces. may The nickel plating layer 224 is preferably provided at least on the liquid-contacting portions of the inner surfaces of the catholyte supply channel and the catholyte recovery channel provided in the flange portions 212 and 222, and is provided on the entire inner surfaces. may In the third frame 210, the first nickel plating layer 214 and the second nickel plating layer 224 may be a continuous nickel plating layer. For example, the first nickel-plated layer 214 and the second nickel-plated layer 224 form the anolyte supply channel and the anolyte recovery channel provided in the first flange portion 212 and the second flange portion 222 and the cathode. An integral continuous nickel plating layer may be formed through the inner surfaces of the liquid supply channel and the catholyte recovery channel. Further, for example, the first nickel plating layer 214 and the second nickel plating layer 224 may form an integral continuous nickel plating layer through the outer peripheral surfaces of the flange portions 212 and 222 .

According to the electrolytic cell 200, the first frame 10 that defines the anode chamber A1 is exposed on the gasket contact surface 12e of the first flange portion 12 and has a thickness of 27 μm or more, more preferably 30 μm or more. The third frame 10, which includes the first nickel plating layer 14, the surface roughness of the gasket contact surface 12e is 10 μm or less as an arithmetic mean roughness Ra, and the third frame 10 defining the anode chamber A2 is provided with the first flange. A first nickel plating layer 214 having a thickness of 27 μm or more, more preferably 30 μm or more, is provided exposed on the gasket contact surface 212e of the portion 212, and the surface roughness of the gasket contact surface 212e is the arithmetic mean roughness Ra is 10 μm or less, it is possible to suppress the deterioration of the sealing performance of the anode liquid and the anode chamber gas.

The present invention will be described more specifically below based on examples and comparative examples. However, the present invention is not limited to these examples.

(Measuring method)
In the following examples and comparative examples, the thickness of the plating layer was measured using an electromagnetic film thickness meter (LE-373, manufactured by Kett Scientific Laboratory Co., Ltd.). The surface roughness was measured using a surface roughness profiler (Surfcom 480A, manufactured by Tokyo Seimitsu Co., Ltd.).

(Preparation of sample)
A steel plate (30 mm long×50 mm wide×10 mm thick) made of rolled steel for welded structures (SM400B) whose edges were chamfered was used as the nickel-plated object. Holes with a diameter of 5 mm were provided at the four corners as bolt holes necessary for sandwiching the gasket. A plurality of types of steel sheet samples were prepared by intentionally adjusting the surface roughness of the steel sheet so that the surface roughness after plating was changed, and a plurality of sheets for each type were prepared. Steel plate samples with different surface roughness were produced by shot blasting using brown alumina (No. 2000 to No. 4000) as an abrasive. The surface roughness in the shot blasting was adjusted by adjusting the grade of the abrasive and the shot time. Each steel plate sample was nickel-plated by electroless nickel plating or electric nickel plating to prepare nickel-plated steel plate samples having different plating thicknesses and surface roughnesses.

　The electroless plating treatment was performed according to the general electroless nickel plating treatment procedure. A steel plate sample was immersed in an acetone solution and ultrasonically degreased for 10 minutes. After that, it was washed with pure water and then immersed in 10% dilute hydrochloric acid for 5 minutes for acid washing. After washing the steel sheet with pure water, it was immersed in an electroless nickel-phosphorus plating solution (medium phosphorus type, "Top Nicolon" (registered trademark) manufactured by Okuno Chemical Industry Co., Ltd.). The temperature of the plating solution was maintained at 90°C. The plating solution was gently stirred while the steel plate was immersed in the plating solution. In order to suppress changes in the composition of the plating bath, the plating solution was replaced as appropriate. The plating film thickness was adjusted by changing the immersion time of the steel sheet in the plating solution. After the steel sheet was pulled out of the plating solution, it was washed with pure water and dried to obtain an electroless nickel-plated test piece. The plating thickness and surface roughness (arithmetic mean roughness Ra and maximum height Rz) of the obtained test piece were measured.

The electroplating treatment was performed in accordance with a general procedure for nickel electroplating. A steel plate sample was immersed in an acetone solution and ultrasonically degreased for 10 minutes. After that, it was washed with pure water and then immersed in 10% dilute hydrochloric acid for 5 minutes for acid washing. After washing the steel sheet with pure water, it was immersed in an electrolytic nickel plating bath solution (Watt bath, nickel sulfate 280 g/L, nickel chloride 45 g/L, boric acid 35 g/L) to an electrodeposition current density of 10 A/ ^dm2. A nickel plating layer was electrodeposited. During the plating process, the temperature of the plating bath solution was maintained at 45° C. and the plating solution was gently stirred. In order to suppress changes in the composition of the plating bath, the plating solution was replaced as appropriate. After a nickel plating layer was electrodeposited until a predetermined plating film thickness was obtained, the steel sheet was pulled out of the plating bath, washed with pure water and dried to obtain an electro-nickel-plated test piece. The plating thickness and surface roughness (arithmetic mean roughness Ra and maximum height Rz) of the obtained test piece were measured.

A flat gasket (made of EPDM, 30 mm long x 50 mm wide x 3 mm thick) was sandwiched between two test pieces that had the same surface roughness and were electroless nickel plated or electronic nickel plated. A sample for immersion was produced by tightening and fixing with a press surface pressure (1.5 kgf/cm ² ) equivalent to that of an actual machine.

<Examples 1 to 5 and Comparative Examples 1 to 5>
(Alkaline immersion-salt spray test (1))
Tables 1 and 2 show the properties of each immersion sample before and after plating. Each immersion sample was immersed in an alkaline solution (30% by mass aqueous potassium hydroxide solution, 100° C.) for 240 hours. This is a more severe condition for metal corrosion than normal electrolytes in alkaline water electrolysers. After the sample for immersion was pulled out of the alkaline solution, it was disassembled, washed with water and dried. The surface where the test piece was in contact with the gasket (surface to be tested) was subjected to a salt spray test using a neutral sodium chloride aqueous solution in accordance with JIS Z2371. The condition was observed and evaluated on a scale of 1-3. The evaluation criteria are as follows.
3: No red rust was observed and no discoloration was observed. 2: No red rust was observed, but discoloration was observed. 1: Both red rust and discoloration were observed on a wide surface. Shown in Tables 1-2.

In the above alkali immersion-salt water spray test, if there is a portion where the nickel plating is deteriorated on the test surface, the score will be worse. Then, when the test piece is fastened together with the gasket and immersed in the alkaline solution, the worse the sealing performance between the test piece and the gasket, the larger the amount of alkaline solution that penetrates into the wide area between the test piece and the gasket. Therefore, the nickel plating on the surface to be tested tends to deteriorate over a wide area. If the nickel plating deteriorates, the alkaline solution will further enter the deteriorated portion, resulting in a vicious cycle of further deterioration of the sealing performance. All of the test pieces of Examples 1 to 5 showed good results in the alkali immersion-salt water spray test.
The test pieces of Comparative Examples 1 to 5, in which the surface roughness of the plated steel sheet exceeded 10 μm as an arithmetic mean roughness Ra, were inferior in the alkali immersion-salt water spray test even though the plating thickness was 27 μm or more. showed the results.

<Example 6 and Comparative Examples 6-7>
(Alkaline immersion-salt spray test (2))
Table 3 shows the properties of each immersion sample before and after plating. Each immersion sample was immersed in an alkaline solution (48% by mass potassium hydroxide aqueous solution, 120° C.) for 2000 hours. This is a more severe condition for metal corrosion than the conditions in Examples 1-5 and Comparative Examples 1-5. After the sample for immersion was pulled out of the alkaline solution, it was disassembled, washed with water and dried. The surface of the test piece in contact with the gasket (surface to be tested) was subjected to the same salt spray test as described above, and the surface condition of the surface to be tested was evaluated after 72 hours. Table 3 shows the results.

Similarly, in the alkali immersion-salt water spray test conducted for Example 6 and Comparative Examples 6 and 7, if there is a portion where the nickel plating is deteriorated on the test object surface, the score deteriorates. Then, when the test piece is fastened together with the gasket and immersed in the alkaline solution, the worse the sealing performance between the test piece and the gasket, the larger the amount of alkaline solution that penetrates into the wide area between the test piece and the gasket. Therefore, the nickel plating on the surface to be tested tends to deteriorate over a wide area. If the nickel plating deteriorates, the alkaline solution will further enter the deteriorated portion, resulting in a vicious cycle of further deterioration of the sealing performance. In this test, the corrosiveness of the alkaline solution is higher than in the tests of Examples 1 to 5 and Comparative Examples 1 to 5, and the alkaline immersion time is longer, so this vicious circle is more likely to progress. However, the specimen of Example 6 performed well in the alkaline immersion-salt spray test.
The test pieces of Comparative Examples 6 and 7, which had a plating thickness of less than 27 μm, were inferior in the alkali immersion-salt water spray test even though the surface roughness of the steel plate after plating was 10 μm or less as an arithmetic mean roughness Ra. showed the results.

From the above results, it is considered that the alkaline water electrolytic cell of the present invention can suppress the deterioration of the sealing performance between the anolyte and the anode chamber gas even on the anode chamber side, where conditions for metal corrosion are severe. . In addition, it is thought that it is possible to extend the life of the nickel plating on the gasket contact surface of the flange even under severe conditions for metal corrosion.

10 first frame 20 second frame 210 third frame 10a, 20a, 210a (made of steel) core material 14, 214 first nickel plating layer 24, 224 second nickel plating layer 11, 21, 211 (conductive) partition 12, 212 first flange portion 22, 222 second flange portion 13, 213, 23, 223 (conductive) support member 30 gasket 31 first gasket element 32 second gasket element 40 (ion-permeable) diaphragm 50 anode 60 cathode 100, 200 electrolytic cell A, A1, A2 anode chamber C, C1, C2 cathode chamber

Claims (14)

1. a first frame comprising a conductive first partition and a first flange portion provided on the outer peripheral portion of the first partition and defining an anode chamber;
   a second frame comprising a conductive second partition and a second flange portion provided on the outer peripheral portion of the second partition and defining a cathode chamber;
   an ion-permeable diaphragm disposed between the first frame and the second frame to separate the anode chamber and the cathode chamber;
   a gasket sandwiched between a first flange portion of the first frame and a second flange portion of the second frame to hold the diaphragm;
   an anode disposed in the anode chamber and electrically connected to the first partition;
   a cathode disposed in the cathode chamber and electrically connected to the second partition;
   with
   The gasket is
   a first gasket element contacting the first flange portion and the diaphragm;
   a second gasket element contacting the second flange and the diaphragm;
   the first flange portion comprises a first gasket contact surface in contact with the first gasket element;
   The first frame includes a first nickel-plated layer having a thickness of 27 μm or more, which is exposed on the first gasket contact surface of the first flange,
   The alkaline water electrolytic bath, wherein the surface roughness of the first gasket contact surface is 10 µm or less as an arithmetic mean roughness Ra.
2. The alkaline water electrolytic cell according to claim 1, wherein the surface roughness of the first gasket contact surface is 40 µm or less as the maximum height Rz.
3. The alkaline water electrolytic bath according to claim 1 or 2, wherein the first nickel plating layer is an electroless nickel plating layer.
4. The first frame is
   at least one steel first core;
   3. The alkaline water electrolytic cell according to claim 1, further comprising said first nickel plating layer provided on the surface of said first core material.
5. 3. The first nickel plating layer according to claim 1, wherein the first nickel plating layer is continuously provided on the first gasket contact surface and the surface of the first frame facing the anode chamber. alkaline water electrolyzer.
6. The alkaline water electrolytic cell according to claim 1 or 2, wherein the thickness of the first nickel plating layer is 30 to 100 µm.
7. The first frame is
   3. The alkaline water electrolytic cell according to claim 1, further comprising a conductive support member protruding from said first partition into said anode chamber and supporting said anode.
8. the second flange portion comprises a second gasket contact surface in contact with the second gasket element;
   The second frame includes a second nickel-plated layer having a thickness of 27 μm or more, which is exposed on the second gasket contact surface of the second flange,
   3. The alkaline water electrolytic cell according to claim 1, wherein the surface roughness of said second gasket contact surface is 10 [mu]m or less as an arithmetic mean roughness Ra.
9. The alkaline water electrolytic cell according to claim 8, wherein the second gasket contact surface has a surface roughness of 40 µm or less as a maximum height Rz.
10. The alkaline water electrolytic bath according to claim 8, wherein the second nickel plating layer is an electroless nickel plating layer.
11. The second frame is
    at least one steel second core;
    9. The alkaline water electrolytic cell according to claim 8, further comprising said second nickel plating layer provided on the surface of said second core material.
12. 9. The alkali according to claim 8, wherein the second nickel plating layer is continuously provided on the second gasket contact surface and the surface of the second frame facing the cathode chamber. Water electrolyzer.
13. The alkaline water electrolytic cell according to claim 8, wherein the second nickel plating layer has a thickness of 50 to 100 µm.
14. The second frame is
    3. The alkaline water electrolytic cell according to claim 1, further comprising a conductive support member protruding from said second partition into said cathode chamber and supporting said cathode.

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