WO2018139597A1

WO2018139597A1 - Electrolytic cell, electrolysis device, and electrolysis method

Info

Publication number: WO2018139597A1
Application number: PCT/JP2018/002541
Authority: WO
Inventors: 陽介内野; 伸司長谷川; 悠介鈴木; 亮小村; 則和藤本
Original assignee: 旭化成株式会社
Priority date: 2017-01-26
Filing date: 2018-01-26
Publication date: 2018-08-02
Also published as: JPWO2018139597A1; JP6803406B2

Abstract

Provided are a bipolar electrolytic cell, electrolysis device, and water electrolysis method, said bipolar electrolytic cell being provided with a header, whereon a plurality of bipolar elements provided with a negative electrode, a positive electrode, a partition wall separating the positive electrode a negative electrode, and an outer frame bordering the partition wall are stacked sandwiching barrier membranes, for linking to an electrode chamber defined by the partition walls, outer frame, and barrier membranes, wherein the bipolar electrolytic cell is characterized in that the capacitance of the positive electrode is in a range of 4825 – 965000 C/m² and the capacitance of the negative electrode is in a range of 4825 – 965000 C/m².

Description

Electrolysis tank, electrolysis device, electrolysis method

The present invention relates to a bipolar electrolyzer, an electrolyzer, and a water electrolysis method.

In recent years, in order to solve problems such as global warming caused by greenhouse gases such as carbon dioxide and a decrease in reserves of fossil fuels, technologies such as wind power generation and solar power generation using renewable energy have attracted attention.

∙ Renewable energy has the characteristic that its output varies greatly because it depends on climatic conditions. For this reason, it is not always possible to transport the power obtained by power generation using renewable energy to the general power system, and there are concerns about social impacts such as imbalance in power supply and demand and instability of the power system. Yes.

Therefore, research is being conducted to use electric power generated from renewable energy in a form that can be stored and transported. Specifically, it is considered to generate hydrogen that can be stored and transported by electrolysis (electrolysis) of water using electric power generated from renewable energy, and to use hydrogen as an energy source or raw material. Yes.

Hydrogen is widely used industrially in scenes such as petroleum refining, chemical synthesis, and metal refining. In recent years, hydrogen can be used in hydrogen stations for fuel cell vehicles (FCV), smart communities, hydrogen power plants, etc. Sex is also spreading. For this reason, there is high expectation for the development of a technology for obtaining particularly high-purity hydrogen from renewable energy.

Water electrolysis methods include solid polymer water electrolysis, high temperature steam electrolysis, alkaline water electrolysis and the like. Among them, alkaline water electrolysis is one of the most promising because it has been industrialized for several decades or more, it can be implemented on a large scale, and it is cheaper than other water electrolysis devices. Has been.

However, in order to adapt alkaline water electrolysis as a means for energy storage and transportation in the future, as described above, it is possible to perform water electrolysis efficiently and stably using electric power with large output fluctuations. There is a need to. Therefore, it is required to solve various problems of electrolytic cells and apparatuses for alkaline water electrolysis.

In order to solve the problem of suppressing the electrolysis voltage in alkaline water electrolysis and improving the power unit of hydrogen production, the structure of the electrolysis cell, in particular, the structure in which the gap between the diaphragm and the electrode is substantially eliminated It is well known that it is effective to adopt a structure called a zero gap structure (see Patent Documents 1 and 2). In the zero gap structure, the generated gas is quickly released to the opposite side of the electrode through the pores of the electrode, thereby reducing the distance between the electrodes and suppressing the occurrence of gas accumulation near the electrodes as much as possible. The voltage is kept low. The zero gap structure is extremely effective for suppressing the electrolysis voltage, and is used in various electrolysis apparatuses.

On the other hand, in order to realize efficient and stable alkaline water electrolysis, it is also reported by Detlefolten et al. That the optimal selection of electrodes and diaphragms, the optimization of the structure of the electrolytic cell, etc. are important ( Non-patent document 1). Furthermore, in recent years, researches have been actively conducted to tackle the above-described problems with respect to an electrolytic cell for alkaline water electrolysis having a zero gap structure (see Patent Documents 3 and 4).

US Pat. No. 4,530,743 JP 59-173281 A International Publication No. 2013/191140 International Publication No. 2014/178317

However, various types of bipolar electrolyzers have been developed so far, but in order to operate stably when changing electric power such as renewable energy to such an electrolyzer, However, it is necessary to control a complicated electric drive control system. However, since the electric drive control system cannot be controlled in the event of sudden power supply interruption, improvement has been demanded.

Therefore, the present invention has an object of enabling hydrogen production with high efficiency during operation with a variable power source such as renewable energy, and further stabilizing the electric control system when the power supply is stopped. .

The gist of the present invention is as follows.
The bipolar electrolytic cell according to the present invention includes a plurality of bipolar elements each including an anode, a cathode, a partition wall that separates the anode and the cathode, and an outer frame that borders the partition wall with a diaphragm interposed therebetween. And a bipolar electrolytic cell comprising a header communicating with an electrode chamber defined by the partition wall, the outer frame, and the diaphragm, outside the outer frame,
The electric capacity of the anode is in the range of 4825 C / m ² to 965000 C / m ² , and the electric capacity of the cathode is in the range of 4825 C / m ² to 965000 C / m ² .
It is characterized by that.
Here, the bipolar electrolytic cell of the present invention is preferably a bipolar electrolytic cell for alkaline water electrolysis.
In the bipolar electrolytic cell of the present invention, the area of the current-carrying surface of the bipolar element is S1, the sectional area of the header channel is S2, and the length of the header channel is L2. , (S2 / S1) / L2 is preferably in the range of 1.5 × 10 ⁻⁶ m ⁻¹ to 2.3 × 10 ⁻⁴ m ⁻¹ .
Further, in the bipolar electrolytic cell of the present invention, it is preferable that the lower one of the electric capacity of the anode and the electric capacity of the cathode is in the range of 9650 C / m ² to 955350 C / m ² .
Further, in the bipolar electrolytic cell of the present invention, it is preferable that the electric capacity of the anode is larger than the electric capacity of the cathode.
Furthermore, in the bipolar electrolytic cell of the present invention, it is preferable that the electric capacity of the cathode is more than 0.1 times and not more than 0.99 times the electric capacity of the anode.
Furthermore, in the bipolar electrolytic cell of the present invention, it is preferable that the electric capacity of the cathode exceeds 0.1 times the electric capacity of the anode and is not more than 0.49 times.
In the bipolar electrolytic cell of the present invention, the actual electrode surface area per 1 m ² of the geometric cell area of the anode is preferably in the range of 90 m ² to 10000 m ² .
Furthermore, the bipolar electrolytic cell of the present invention preferably has 50 to 500 bipolar elements.
Furthermore, in the bipolar electrolytic cell of the present invention, the S1 is preferably 0.1 m ² to 10 m ² .
Furthermore, in the bipolar electrolytic cell of the present invention, the thickness d of the electrolytic cell is preferably 10 mm to 100 mm.
Further, in the bipolar electrolytic cell of the present invention, it is preferable that the anode contains at least one nickel compound selected from the group consisting of nickel oxide, metallic nickel, nickel hydroxide and nickel alloy.
Further, in the bipolar electrolytic cell of the present invention, the anode has a conductive substrate and a catalyst layer disposed on the conductive substrate, and the catalyst layer includes a metal crystal of nickel, And the specific surface area of the first pores having pores in the range of 2 to 5 nm among the pores of the catalyst layer is 0.6 to 2.0 m ² / g, The pore volume of one pore is 3 × 10 ⁻⁴ to 9 × 10 ⁻⁴ ml / g, and among the pores, the second pore having a pore diameter in the range of 0.01 to 2.00 μm The specific surface area is 2.0 to 5.0 m ² / g, the pore volume of the second pore is 0.04 to 0.2 ml / g, and the thickness of the catalyst layer is 50 to 800 μm. Is preferred.
Further, in the bipolar electrolytic cell of the present invention, the cathode is Ru—La—Pt, Ru—Ce, Pt—Ce, Pt—Ir, Ir—Pt—Pd, Pt—Ni. It is preferable to include at least one Pt group compound selected from the group consisting of:
Further, in the bipolar electrolytic cell of the present invention, the structure of the cathode and anode has a catalyst layer on the surface of the conductive substrate, and the conductive substrate is made of nickel metal, nickel oxide, hydroxide It is preferable to contain at least one nickel compound selected from the group consisting of nickel and nickel alloys.
Furthermore, in the bipolar electrolytic cell of the present invention, it is preferable that the cathode and the anode have a mesh structure.
Furthermore, in the bipolar electrolytic cell of the present invention, it is preferable that the cathode base material has a wire diameter in the range of 0.05 mm to 0.5 mm, and the opening has a range of 30 mesh to 80 mesh. .
Further, in the bipolar electrolytic cell of the present invention, it is preferable that the anode base material has a mesh structure having an opening ratio in the range of 20% to 60%.
Furthermore, the bipolar electrolytic cell of the present invention is preferably one in which electrolytic cells are electrically connected in series.
Further, the bipolar electrolytic cell of the present invention comprises a bipolar element having the cathode, the anode, the diaphragm, and a partition partitioning the anode chamber and the cathode chamber, and the diaphragm is located between the cathode and the anode. The diaphragm is preferably in contact with the cathode and the anode.

The electrolytic apparatus of the present invention includes a bipolar electrolytic cell of the present invention, an electrolytic solution circulation pump for circulating the electrolytic solution, a gas-liquid separation tank for separating the electrolytic solution from hydrogen and / or oxygen, and water. And a water supply pump for replenishment.
The electrolysis apparatus of the present invention may further include a detector that detects the stop of power supply when the power supply to the electrolysis apparatus of the present invention is stopped, and a controller that automatically stops the electrolyte circulation pump. preferable.

The water electrolysis method of the present invention is characterized in that when the power supply to the electrolyzer of the present invention is stopped, the electrolyte circulation pump is stopped.

The hydrogen production method of the present invention is a hydrogen production method in which water containing an alkali is electrolyzed in an electrolytic cell to produce hydrogen, wherein the electrolytic cell isolates the anode, the cathode, and the anode and the cathode. A plurality of bipolar elements including a partition and an outer frame that borders the partition are stacked with a diaphragm interposed therebetween, and are defined by the partition, the outer frame, and the diaphragm on the outer side of the outer frame. And a header communicating with the electrode chamber, wherein the anode has an electric capacity in the range of 4825 C / m ² to 965000 C / m ² , and the cathode has an electric capacity of 4825 C / m ² to 965000 C. / M ² range.

According to the present invention, it is possible to produce hydrogen with high efficiency during operation with a variable power source such as renewable energy, and to stabilize an electric control system when power supply is stopped.

It is a side view shown about the whole example of the bipolar electrolytic cell for alkaline water electrolysis of this embodiment. It is a perspective view shown about an electrolysis room, a header, and a conduit of an example of a bipolar electrolytic cell for alkaline water electrolysis of this embodiment. It is a perspective view which shows the flow of the electrolyte solution in an example of the bipolar electrolytic cell for alkaline water electrolysis of this embodiment. It is a top view which shows the example of the bipolar-type electrolytic cell for external water type | molds of the external header type of this embodiment. It is a figure which shows the outline | summary of the electrolyzer for alkaline water electrolysis of this embodiment.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

In FIG. 1, the side view about the whole example of the bipolar electrolytic cell for alkaline water electrolysis of this embodiment is shown.
FIG. 2 shows a perspective view of an electrolysis chamber, a header, and a conduit as an example of the bipolar electrolytic cell for alkaline water electrolysis according to the present embodiment.
In FIG. 3, the perspective view about the flow of the electrolyte solution in an example of the bipolar electrolytic cell for alkaline water electrolysis of this embodiment is shown.
As shown in FIG. 1, a bipolar electrolytic cell 50 for alkaline water electrolysis according to this embodiment includes an anode 2a, a cathode 2c, a partition wall 1 that separates the anode 2a and the cathode 2c, and an outer frame that borders the partition wall 1. 3 is a bipolar electrolyzer 50 in which a plurality of bipolar elements 60 including 3 are overlapped with a diaphragm 4 interposed therebetween.

(Bipolar electrolytic cell)
The bipolar method is one of the methods for connecting a large number of cells to a power source. A plurality of bipolar elements 60, one side of which is an anode 2a and one side of which is a cathode 2c, are arranged in the same direction and connected in series, and only at both ends. Is connected to a power source.
The bipolar electrolytic cell 50 has a feature that the current of the power source can be reduced, and can produce a large amount of a compound, a predetermined substance, etc. in a short time by electrolysis. As long as the output of the power supply equipment is the same, the constant current and high voltage are cheaper and more compact, so the bipolar type is preferable to the single pole type industrially.

((Bipolar element))
As shown in FIG. 1, a bipolar element 60 used in a bipolar electrolytic cell 50 for alkaline water electrolysis is provided with a partition wall 1 that separates an anode 2a and a cathode 2c, and an outer frame that borders the partition wall 1 3 is provided. More specifically, the partition wall 1 has conductivity, and the outer frame 3 is provided so as to surround the partition wall 1 along the outer edge of the partition wall 1.

In this embodiment, the bipolar element 60 may be used so that a given direction D1 along the partition wall 1 is usually a vertical direction. Specifically, in FIG. 2 and FIG. As shown in the figure, when the shape of the partition wall 1 is rectangular, it is used so that a given direction D1 along the partition wall 1 is the same direction as the direction of one of the two pairs of facing edges. (See FIGS. 1 to 5). And in this specification, the said perpendicular direction is also called electrolyte solution passage direction.

In the present embodiment, as shown in FIG. 1, the bipolar electrolytic cell 50 is configured by stacking a necessary number of bipolar elements 60.
In the example shown in FIG. 1, the bipolar electrolytic cell 50 has a fast head 51g, an insulating plate 51i, and an anode terminal element 51a arranged in order from one end, and further, an anode side gasket portion 7, a diaphragm 4, and a cathode side gasket portion. 7. Bipolar elements 60 are arranged in this order. At this time, the bipolar element 60 is arranged so that the cathode 2c faces the anode terminal element 51a side. The anode gasket portion 7 to the bipolar element 60 are repeatedly arranged as many times as necessary for the design production amount. After the necessary number of anode-side gasket portions 7 to the bipolar element 60 are repeatedly arranged, the anode-side gasket portion 7, the diaphragm 4, and the cathode-side gasket portion 7 are arranged again, and finally, the cathode terminal element 51c and the insulation The plate 51i and the loose head 51g are arranged in this order. The bipolar electrolyzer 50 is formed into a single body by tightening the whole by a tightening mechanism such as a tie rod method 51r (see FIG. 1) or a hydraulic cylinder method.
The arrangement constituting the bipolar electrolytic cell 50 can be arbitrarily selected from the anode 2a side or the cathode 2c side, and is not limited to the order described above.

As shown in FIG. 1, in the bipolar electrolytic cell 50, the bipolar element 60 is disposed between the anode terminal element 51a and the cathode terminal element 51c. The diaphragm 4 is disposed between the anode terminal element 51a and the bipolar element 60, between the adjacent bipolar elements 60, and between the bipolar element 60 and the cathode terminal element 51c. .

In the bipolar electrolytic cell 50 according to the present embodiment, as shown in FIGS. 2 and 3, an electrode chamber 5 through which an electrolytic solution passes is defined by the partition wall 1, the outer frame 3, and the diaphragm 4.

In the present embodiment, in particular, in the bipolar electrolytic cell 50, the portion between the two adjacent bipolar elements 60 between the partition walls 1 and between the adjacent bipolar element 60 and the terminal element. A portion between the partition walls 1 is referred to as an electrolysis cell 65. The electrolysis cell 65 includes a partition 1 of one element, an anode chamber 5a, an anode 2a, and a diaphragm 4, and a cathode 2c, a cathode chamber 5c, and a partition 1 of the other element.

Specifically, the electrode chamber 5 has an electrolyte inlet 5 i for introducing an electrolyte into the electrode chamber 5 and an electrolyte outlet 5 o for leading the electrolyte from the electrode chamber 5 at the boundary with the outer frame 3. More specifically, the anode chamber 5a is provided with an anode electrolyte inlet 5ai that introduces an electrolyte into the anode chamber 5a and an anode electrolyte outlet 5ao that leads out the electrolyte derived from the anode chamber 5a. Similarly, the cathode chamber 5c is provided with a cathode electrolyte inlet 5ci that introduces an electrolyte into the cathode chamber 5c and a cathode electrolyte outlet 5co that leads out the electrolyte led out from the cathode chamber 5c.

The bipolar electrolytic cell 50 in the present embodiment includes a header 10 communicating with the electrode chamber 5 outside the outer frame 3 (see FIGS. 2 and 3).

In the example shown in FIGS. 2 and 3, the header 10, which is a pipe for distributing or collecting a gas or an electrolytic solution, is attached to the bipolar electrolytic cell 50. Specifically, the header 10 includes an inlet header for introducing an electrolytic solution into the electrode chamber 5 and an outlet header for discharging a gas and an electrolytic solution from the electrode chamber 5.
In one example, an anode inlet header 10Oai that puts the electrolyte into the anode chamber 5a and a cathode inlet header 10Oci that puts the electrolyte into the cathode chamber 5c are provided below the outer frame 3 at the edge of the partition wall 1. Similarly, on the side of the outer frame 3 at the edge of the partition wall 1, an anode outlet header 10Oao for discharging the electrode solution from the anode chamber 5a and a cathode outlet header 10Oco for discharging the electrolyte solution from the cathode chamber 5c are provided. .
In one example, in the anode chamber 5 a and the cathode chamber 5 c, the inlet header and the outlet header are provided so as to face each other with the central portion of the electrode chamber 5 interposed therebetween.

In particular, the bipolar electrolytic cell 50 of this example employs an external header 10O type in which the bipolar electrolytic cell 50 and the header 10 are independent.
FIG. 4 is a plan view showing an example of the external header type bipolar electrolytic cell for alkaline water electrolysis according to this embodiment.

In addition, as an arrangement mode of the header 10 attached to the bipolar electrolytic cell shown in FIGS. 1 to 3, there are typically an internal header 10I type and an external header 10O type. A mold may be adopted and is not particularly limited.

Further, in the example shown in FIGS. 2 and 3, a conduit 20, which is a tube that collects gas and electrolyte solution distributed or collected in the header 10, is attached to the header 10. Specifically, the conduit 20 includes a liquid distribution pipe that communicates with the inlet header and a liquid collection pipe that communicates with the outlet header.
In one example, below the outer frame 3, the anode liquid distribution tube 20Oai communicating with the anode inlet header 10Oai and the cathode liquid distribution tube 20Oci communicating with the cathode inlet header 10Oci are provided. Further, on the side of the outer frame 3, an anode liquid collecting tube 20Oao communicating with the anode outlet header 10Oao and a cathode liquid collecting tube 20Oco communicating with the cathode outlet header 10Oco are provided.

In the present embodiment, in the anode chamber 5a and the cathode chamber 5c, the inlet header and the outlet header are preferably provided at separate positions from the viewpoint of water electrolysis efficiency, and face each other across the central portion of the electrode chamber 5. As shown in FIGS. 2 and 3, when the partition wall 1 has a rectangular shape in plan view, it is preferably provided so as to be symmetric with respect to the center of the rectangle.

Usually, as shown in FIGS. 2 and 3, the anode inlet header 10Oai, the cathode inlet header 10Oci, the anode outlet header 10Oao, and the cathode outlet header 10Oco are provided one by one in each electrode chamber 5, but in this embodiment, However, the present invention is not limited to this, and a plurality of electrode chambers 5 may be provided.
Further, normally, the anode liquid distribution pipe 20Oai, the cathode liquid distribution pipe 20Oci, the anode liquid collection pipe 20Oao, and the cathode liquid collection pipe 20Oco are provided one by one in each electrode chamber 5, but in this embodiment, However, the present invention is not limited to this, and a plurality of electrode chambers 5 may be shared.

In the illustrated example, the rectangular partition wall 1 in plan view and the rectangular diaphragm 4 in plan view are arranged in parallel, and the rectangular parallelepiped outer frame provided on the edge of the partition wall 1 side. Since the inner surface of the electrode chamber 5 is perpendicular to the partition wall 1, the shape of the electrode chamber 5 is a rectangular parallelepiped. However, in the present invention, the shape of the electrode chamber 5 is not limited to the rectangular parallelepiped in the illustrated example, and the shape of the partition wall 1 and the diaphragm 4 in a plan view, the inner surface of the outer frame 3 on the partition wall 1 side, and the partition wall 1. The shape may be appropriately changed depending on the angle or the like, and may be any shape as long as the effect of the present invention is obtained.

In this embodiment, the extending direction of the header 10 is not particularly limited.

In the present embodiment, the extending direction of the conduit 20 is not particularly limited. However, as in the example illustrated in FIGS. 2 and 3, from the viewpoint of easily obtaining the effect of the present invention, the distribution pipe (anode liquid distribution) is used. The pipe 20Oai, the cathode liquid distribution pipe 20Oci) and the liquid collection pipe (anode liquid collection pipe 20Oao, cathode liquid collection pipe 20Oco) preferably extend in a direction perpendicular to the partition wall 1, respectively. It is more preferable that any of these extend in a direction perpendicular to the partition wall 1.

Sometimes, the electrolytic cell 65 undergoes a self-discharge reaction via a leakage current circuit formed by the electrolyte supply pipe when electrolysis is stopped.

A structure having electric capacity for holding the cell voltage of the electrolysis cell 65 even when the self-discharge occurs is called a charge holding body. The charge holding body can be electrically connected to the cathode 2c or the anode 2a inside the cathode chamber 5c or the anode chamber 5a, and the electrochemical potential of the cathode 2c or the anode 2a can be stabilized for a long time. The electrolytic cell can be used as an emergency storage battery when power supply is stopped.

In the present embodiment, the cathode 2c or the anode 2a is composed of a catalyst layer and a substrate that supports the catalyst layer, and the catalyst layer and the substrate have a function of a charge holding body.

Here, in the bipolar electrolytic cell 50 for alkaline water electrolysis of the present embodiment, the electric capacity of the anode 2a is in the range of 4825 C / m ² to 965000 C / m ² (0.05 Fd / m ² to 10 Fd / m ² ). And the electric capacity of the cathode 2c is in the range of 4825 C / m ² to 965000 C / m ² (0.05 Fd / m ² to 10 Fd / m ² ).

During operation with a variable power source such as renewable energy, the amount of electricity held in the electrolytic cell is increased and balanced by the function of the charge holding body of the electrode chamber 5, and further, by improving the structure of the electrolyte supply pipe, By reducing the self-discharge generated when the power supply is stopped, the electrolytic cell can be used as an emergency storage battery when the power supply is stopped, and the electric control system can be stabilized even in an emergency.

In the present embodiment, in view of enhancing the effect of the present invention, the capacitance of the anode 2a ^is more preferably in a range of ^{9650C / m 2 ~ 772000C / m} 2, the range of ^{48250C / m 2 ~ 482500C / m} 2 Most preferably. Capacitance of the cathode 2c ^is more preferably in a range of ^{9650C / m 2 ~ 772000C / m} 2, and most preferably in the range of ^{48250C / m 2 ~ 482500C / m} 2.

In the bipolar electrolytic cell 50 for alkaline water electrolysis of the present embodiment, the lower one of the electric capacity of the anode 2a and the electric capacity of the cathode 2c is preferably in the range of 9650 C / m ² to 955350 C / m ² , and 48250 C / A range of m ² to 772000 C / m ² is more preferable, and a range of 96500 C / m ² to 482500 C / m ² is particularly preferable.
If the lower one of the electric capacities is too small, it will be difficult to function as a power source, and if the lower one of the electric capacities is too large, it will be difficult to manufacture substantially.

In the bipolar electrolytic cell 50 for alkaline water electrolysis according to the present embodiment, the electric capacity of the anode is preferably larger than the electric capacity of the cathode. In this case, the ratio of the electric capacity of the cathode to the electric capacity of the anode is 0. It is preferably in the range of more than 1 times and not more than 0.99 times, and more preferably in the range of more than 0.1 times and not more than 0.49 times.

In addition, regarding the electrode 2 (anode 2a, cathode 2c), in addition to the electrode 2 (anode 2a, cathode 2c), an electrode complex including a conductive elastic body 2e and a current collector 2r (anode complex, cathode complex) When is used, the above-described capacitance may be determined for the electrode composite (anode composite, cathode composite).

The effect of the present invention is not easily subject to physical restrictions regarding header design, and it is structurally easy to shut off the electrolyte discharge line (exit header) on the electrolyte outlet 5o side when electrolysis is stopped. It is easy to obtain in an external header 10O type alkaline water electrolytic cell in which an electrolyte supply header to each electrolytic cell 65 is disposed outside the electrolytic cell 65.

In the bipolar electrolytic cell 50 for alkaline water electrolysis of the present embodiment, the area of the energization surface of the bipolar element 60 is S1, the cross-sectional area of the flow path of the header 10 is S2, and the length of the flow path of the header 10 is L2. (S2 / S1) / L2 is preferably in the range of 1.5 × 10 ⁻⁶ m ⁻¹ to 2.3 × 10 ⁻⁴ m ⁻¹ , and 4.0 × 10 ⁻⁶ m. More preferably, it is in the range of ⁻¹ to 2.0 × 10 ⁻⁴ m ^{−1, particularly in} the range of 8.0 × 10 ⁻⁶ m ⁻¹ to 1.0 × 10 ⁻⁴ m ^−1. preferable.

The area S1 of the current-carrying surface of the bipolar element 60 refers to the area on the plane parallel to the partition walls of the electrodes (anode 2a and cathode 2c) of the bipolar element 60. In addition, when the said area differs in the anode 2a and the cathode 2c, it shall mean the average.
The cross-sectional area S2 of the flow path of the header 10 refers to the cross-sectional area of the internal space of the header 10 through which the electrolyte solution passes. In addition, when there exists a change in a cross-sectional area about the extending direction of the header 10, it shall mean the average of the cross-sectional area. Further, when the cross-sectional areas are different in the anode inlet header 10Oai, the cathode inlet header 10Oci, the anode outlet header 10Oao, and the cathode outlet header 10Oco, the average is assumed.
The length L2 of the flow path of the header 10 refers to the extension length of the internal space through which the electrolyte solution passes. In particular, when the conduit 20 communicating with the header 10 is provided, the connection from the electrolyte inlet 5i of the header 10 to the liquid distribution pipe (conduit 20) or from the electrolyte outlet 5o to the liquid collection pipe (conduit). The length of the part up to the connection part. Moreover, when the said length differs in anode inlet header 10Oai, cathode inlet header 10Oci, anode outlet header 10Oao, and cathode outlet header 10Oco, the average shall be said.

When (S2 / S1) / L2 is in the above range, self-discharge generated when power supply is stopped can be reduced, the electric control system can be stabilized, and power can be stored with high efficiency. Specifically, it is possible to achieve highly efficient hydrogen production by reducing the leakage current.

Further, in the bipolar electrolytic cell 50 for alkaline water electrolysis of the present embodiment, the area S1 of the current-carrying surface of the bipolar element 60 is preferably 0.1 m ² to 10 m ² , and preferably 0.15 m ² to 8 m. ² is more preferable, and 0.2 m ² to 5 m ² is particularly preferable.
If the current-carrying surface is too small, the electrolyte supply header also becomes small, making it difficult to manufacture the electrolytic cell 50. On the other hand, if the energizing surface is too large, the seal surface pressure is likely to be non-uniform, causing electrolyte leakage and gas leakage.

Further, in the bipolar electrolytic cell 50 for alkaline water electrolysis of the present embodiment, the thickness d of the electrolytic cell 65 is preferably 10 mm to 100 mm, more preferably 15 mm to 50 mm, and 20 mm to 40 mm. It is particularly preferred.
The thickness d of the electrolysis cell 65 is the thickness of the portion between the partition walls 1 between the two adjacent bipolar elements 60, and between the adjacent bipolar element 60 and the

terminal elements

51a and 51c. The thickness of the portion between the partition walls 1 between each other, and the distance in the direction perpendicular to the partition wall 1 between the partition walls 1 of the two adjacent bipolar elements 60 and the adjacent bipolar system The distance in the direction perpendicular to the partition wall 1 between the partition wall 1 of the element 60 and the partition walls 1 of the

terminal elements

51a and 51c. When the thickness d is not constant in the entire bipolar electrolytic cell 50, the average may be referred to.
If the thickness d of the electrolysis cell is too small, the gas ratio in the gas liquid chamber of the electrolysis cell 65 tends to increase, and the cell voltage tends to increase. If the thickness d is too large, uniform distribution becomes difficult due to the pressure loss of the header 10, and the installation area becomes too large.

Furthermore, in the bipolar electrolytic cell 50 for alkaline water electrolysis according to the present embodiment, S2 is selected from the viewpoint of further purifying the gas purity and suppressing the blockage of the channel due to the solids present in the circulation channel. 7.00 × 10 ⁻⁷ m ² to 3.14 × 10 ⁻⁴ m ² , preferably 1.0 × 10 ⁻⁶ m ² to 2.0 × 10 ⁻⁴ m ^2. preferable.

Furthermore, in the bipolar electrolytic cell 50 for alkaline water electrolysis of the present embodiment, although not particularly limited, L2 is 0.2 to 10 m from the same viewpoint as in the preferred range of S2. It is preferable that the distance is 0.4 to 8 m.

The bipolar electrolytic cell 50 for alkaline water electrolysis of this embodiment preferably has 50 to 500 bipolar elements 60, more preferably 70 to 300 bipolar elements 60, and more preferably 100 to 200. It is particularly preferable to have the bipolar element 60.
If it is less than the lower limit, the ratio of the tightening mechanism to the cell becomes relatively large, which increases the manufacturing cost and increases the installation area of the equipment, which may not be a realistic equipment. In the case of exceeding the upper limit, the self-discharge generated when the power supply is stopped is reduced, the effect of enabling the stabilization of the electric control system, and the storage of power with high efficiency, specifically, the pump It becomes difficult to align effects that enable reduction of power and reduction of leakage current.
Further, if the number (logarithm) of the bipolar element 60 is excessively increased, it may be difficult to manufacture the electrolytic cell 50. When a large number of the bipolar elements 60 having poor manufacturing accuracy are stacked, the seal surface pressure is increased. Tends to be non-uniform, and electrolyte leakage and gas leakage are likely to occur.

Hereinafter, the components of the bipolar electrolytic cell 50 for alkaline water electrolysis according to the present embodiment will be described in detail.
Moreover, below, the suitable form for improving the effect of this invention is also explained in full detail.

-Bulkhead-
The shape of the partition wall 1 in the present embodiment may be a plate shape having a predetermined thickness, but is not particularly limited.
The shape of the partition wall 1 in plan view is not particularly limited, and may be a rectangle (square, rectangle, etc.) or a circle (circle, ellipse, etc.). Here, the rectangle may have rounded corners.
In one embodiment, the partition wall 1 and the outer frame 3 may be integrated by welding or other methods. For example, the flange portion (in the partition wall 1 projecting in a direction perpendicular to the plane of the partition wall 1) ( An anode flange portion protruding to the anode 2 a side and a cathode flange portion protruding to the cathode 2 c side) may be provided, and the flange portion may be a part of the outer frame 3.

In addition, the partition wall 1 may be used so that a given direction D1 along the partition wall 1 is usually a vertical direction. Specifically, as shown in FIGS. When the shape is a rectangle, a given direction D1 along the partition wall 1 may be used so as to be in the same direction as the direction of one of the two sets of sides facing each other. And in this specification, the said perpendicular direction is also called electrolyte solution passage direction.

The material of the partition wall 1 is preferably a conductive material from the viewpoint of realizing uniform power supply, and nickel, nickel alloy, mild steel, and nickel alloy are plated with nickel from the viewpoint of alkali resistance and heat resistance. Is preferred.

-electrode-
In hydrogen production by alkaline water electrolysis according to this embodiment, reduction of energy consumption, specifically reduction of electrolysis voltage, is a big problem. Since this electrolysis voltage largely depends on the electrode 2, the performance of both electrodes 2 is important.

In addition to the voltage required for electrolysis of water, which is theoretically required, the electrolysis voltage of alkaline water electrolysis is the overvoltage of the anode reaction (oxygen generation), the overvoltage of the cathode reaction (hydrogen generation), the anode 2a and the cathode 2c. It is divided into the voltage depending on the distance between the electrodes 2. Here, the overvoltage refers to a voltage that needs to be applied excessively beyond the theoretical decomposition potential when a certain current flows, and the value depends on the current value. When the same current flows, the power consumption can be reduced by using the electrode 2 having a low overvoltage.

In order to realize a low overvoltage, the requirements for the electrode 2 include high conductivity, high oxygen generation capability (or hydrogen generation capability), and high wettability of the electrolyte on the electrode 2 surface. Can be mentioned.

Even if an unstable current such as renewable energy is used as the electrode 2 for alkaline water electrolysis, even if an unstable current such as renewable energy is used, corrosion of the base material and the catalyst layer of the electrode 2, dropping of the catalyst layer, For example, dissolution and adhesion of inclusions to the diaphragm 4 are difficult to occur.

The structure of the conductive substrate of the anode and the cathode is preferably a mesh structure from the viewpoint of ensuring a specific surface area as a carrier and achieving both defoaming properties. The material of the conductive substrate may be at least one selected from the group consisting of nickel iron, vanadium, molybdenum, copper, silver, manganese, platinum group, graphite, chromium and the like. An alloy composed of two or more kinds of metals or a mixture of two or more kinds of conductive substances may be used for the conductive substrate. It is preferable to use metallic nickel for the conductive substrate.

--anode--
The anode 2a includes a conductive substrate and a catalyst layer that covers the conductive substrate, and the catalyst layer is preferably a porous body. The catalyst layer preferably covers the entire surface of the conductive substrate.

The anode catalyst layer preferably contains nickel as an element from the viewpoint of durability against alkalis and high activity against oxygen generation. The catalyst layer preferably contains at least one nickel compound selected from nickel oxide, metallic nickel, nickel hydroxide, and nickel alloy.

The actual electrode surface area (actual specific surface area) per 1 m ² of geometric cell area per anode is preferably in the range of 90 to 10000 m ² . When the actual electrode surface is in a range of less than 90 m ² / m ² , the surface area of the entire catalyst layer is small, so that the oxygen overvoltage is expected to increase. In addition, in the range where the actual electrode surface exceeds 10,000 m ² / m ² , the catalyst layer contains a fine porous material, so that it becomes very brittle, has poor durability, and oxygen overvoltage is expected to increase with oxygen generation. .
The geometric cell area refers to an area when the electrolytic cell 65 is projected in a direction perpendicular to the partition wall 1.
The real electrode surface per the area 1 m ^2, more preferably in the range of 500 ~ 8000m ^² / ^m ^2, and particularly preferably in the range of 1000 ~ 5000m ^² / ^m ^2.

Among the pores in the catalyst layer of the anode, the specific surface area of the first pore having a pore diameter in the range of 2 to 5 nm is 0.6 to 2.0 m ² / g. The volume is preferably 3 × 10 ⁻⁴ to 9 × 10 ⁻⁴ ml / g. Among the pores in the catalyst layer, the specific surface area of the second pores having a pore diameter in the range of 0.01 to 2.00 μm is 2.0 to 5.0 m ² / g, The pore volume is preferably 0.04 to 0.2 ml / g.
The thickness of the catalyst layer is preferably 50 to 800 μm, more preferably 100 to 400 μm.

The second pore having a pore diameter in the range of 0.01 to 2.00 μm has a small specific surface area but a large pore volume, so that the first pore exists on the inner wall of the second pore. Become. The first pores greatly increase the surface area of the catalyst layer. The surface of the first pore functions as a reaction field (reaction interface) of the hydroxide ion oxidation reaction (oxygen generation reaction). Inside the first pore, it is expected that nickel hydroxide will be generated during the generation of oxygen and therefore make the pores smaller. However, since the first pore exists inside the second pore having a large pore diameter, oxygen generated in the first pore easily escapes out of the catalyst layer through the second pore and hardly inhibits electrolysis. . Therefore, in this embodiment, it is estimated that the oxygen generation overvoltage hardly increases during electrolysis.

The specific surface area of the first pore is preferably 0.6 to 1.5 m ² / g, and more preferably 0.6 to 1.0 m ² / g. The specific surface area of the first pore may be 0.62 to 0.98 m ² / g. In general, it is considered that the oxygen generation potential decreases as the specific surface area of the first pore increases. However, if the first pores are too small, the first pores are completely filled with nickel hydroxide generated when oxygen is generated, and the substantial surface area of the first pores tends to be reduced. When the specific surface area of the first pores decreases, the surface area of the entire catalyst layer also tends to decrease. As the surface area of the entire catalyst layer decreases, the oxygen generation potential tends to increase.

The volume of the first pore is preferably 3.3 × 10 ⁻⁴ to 8.5 × 10 ⁻⁴ ml / g. The volume of the first pore may be 3.6 × 10 ⁻⁴ ml / g to 7.9 × 10 ⁻⁴ ml / g. As the pore volume of the first pore increases, the specific surface area tends to decrease. As the pore volume of the first pore decreases, the specific surface area of the entire catalyst layer tends to increase.

The specific surface area of the second pore is preferably 2.3 to 4.5 m ² / g. The specific surface area of the second pore may be 2.5 to 4.2 m ² / g. As the specific surface area of the second pore increases, the pore volume of the entire catalyst layer tends to decrease. Further, the pore volume of the entire catalyst layer tends to increase as the specific surface area of the second pore decreases.

The volume of the second pore is preferably 0.04 to 0.15 ml / g, and more preferably 0.04 to 0.1 ml / g. The volume of the second pore may be 0.04 to 0.09 ml / g. As the pore volume of the second pore increases, the oxygen gas generated in the catalyst layer tends to be easily degassed. As the pore volume of the second pore decreases, the oxygen gas generated in the catalyst layer tends to be difficult to degas, and the oxygen generation overvoltage tends to increase. On the other hand, as the pore volume of the second pore decreases, the mechanical strength of the catalyst layer tends to increase.

If the thickness is less than 50 μm, since the catalyst layer is thin, the surface area of the entire catalyst layer is reduced, and the oxygen overvoltage is expected to be increased. In addition, when the thickness exceeds 800 μm, the catalyst layer becomes too thick, and peeling or the like may easily occur, and the manufacturing cost of the anode may become too high.

The catalyst layer contains nickel metal crystals, the peak intensity of the X-ray diffracted by the (1,1,1) plane of the nickel metal crystals in the catalyst layer is I _Ni , and the NiO in the catalyst layer is (0 , 1, 2) When the peak intensity of the X-ray diffracted by the plane is I _NiO , the value of [I _Ni / (I _Ni + I _NiO )] × 100 is preferably 75 to 100%. I [I _Ni / (I _Ni + I _NiO )] × 100 is more preferably 90 to 100%, and particularly preferably 95 to 100%.

The larger [I _Ni / (I _Ni + I _NiO )] × 100, the lower the electrical resistance of the catalyst layer and the lower the voltage loss when oxygen is generated. In the nickel oxide portion in the catalyst layer, the conductivity is lowered, but the oxygen generation reaction is difficult to occur. Further, since nickel oxide is relatively excellent in chemical stability, it may be effective for the catalyst layer to contain nickel oxide to maintain the strength of the catalyst layer. In addition, _INi and _INiO are calculated | required from the measurement result of XRD ((X-Ray Diffraction) about a catalyst layer.

The catalyst layer may include an alloy composed of nickel and other metals. The catalyst layer is particularly preferably made of metallic nickel. It may further include at least one selected from the group consisting of titanium, chromium, molybdenum, cobalt, tantalum, zirconium, aluminum, zinc, platinum group and rare earth elements. The surface of the catalyst layer may be modified with at least one catalyst selected from the group consisting of rhodium, palladium, iridium, ruthenium and the like.

--- Method of manufacturing anode for alkaline water electrolysis--
The manufacturing method of the anode for alkaline water electrolysis which concerns on this embodiment is not specifically limited. As a preferable production method, there is a method in which expanded nickel is used as a base material, Raney nickel is coated by dispersion plating, and developed with 32 wt% alkali.

--cathode--
The cathode 2c is not particularly limited. It contains at least one Pt group compound selected from the group consisting of Ru—La—Pt, Ru—Ce, Pt—Ce, and Pt—Ir, Ir—Pt—Pd, and Pt—Ni. Is preferred. Further, a pyrolytic active cathode is preferable. The structure of the base material of the cathode is preferably a mesh structure from the viewpoint of ensuring a specific surface area as a carrier and defoaming.

The cathode catalyst layer preferably contains nickel as an element from the viewpoint of durability against alkalis and high activity against hydrogen generation. The catalyst layer preferably contains at least one nickel compound selected from nickel oxide, metallic nickel, nickel hydroxide, and nickel alloy.

In particular, the cathode substrate preferably has a linear shape in the range of 0.05 to 0.5 mm, and the mesh opening has a range of 30 to 80 mesh. By setting it in this range, the specific surface area and defoaming properties required for the carrier can be expressed as the cathode while maintaining the mechanical strength of the mesh. By setting the opening ratio of the mesh of the conductive substrate of the anode in the range of 20% to 60%, the specific surface area and defoaming properties necessary for the carrier can be expressed while maintaining the mechanical strength of the mesh.
In addition, the aperture ratio of an electrode can be measured with the following method.
An electrode based on expanded metal is cut out to a size of about 5 mm × 5 mm, and a desktop microscope Miniscope TM3000 (manufactured by Hitachi High-Technologies Corporation) is used to measure the center distance SW in the short direction and the center distance in the long direction. The LW, the bond length B, the monocular direction length SWO of the opening, and the long direction length LWO of the opening were measured. Using these values, the aperture ratio was calculated according to the following formula.
Opening ratio = SWO × (LWO + B) × 100 / (SW × LW)
Moreover, the electrode which used the plain woven mesh as the base material measured the opening A and the wire diameter d similarly using TM3000, and computed the aperture ratio (%) according to the following formula.
Opening ratio = (A / (A + d)) ² × 100
The calculation method of the aperture ratio of an electrode differs between an electrode using an expanded metal as a base material and an electrode using a plain woven mesh as a base material. In addition, the aperture ratio of the electrode made of a base material other than expanded metal or plain woven mesh is determined by cutting the electrode into a predetermined size (for example, about 5 mm × 5 mm) from the upper side in the vertical direction of the central portion of the electrode left horizontally. Project light, project the electrode downward in the vertical direction, measure the total area of the part through which the light is transmitted and the projected area of the electrode (the total area of the shadow and transmitted light), and calculate according to the following formula be able to.
Aperture ratio = (total area of a portion through which light is transmitted) / (projected area of electrode) × 100

--- Manufacturing method of alkaline water electrolysis cathode--
The manufacturing method of the alkaline water electrolysis cathode according to this embodiment may be the same as the above-described manufacturing method of the anode.

-Outer frame-
The shape of the outer frame 3 in the present embodiment is not particularly limited as long as the partition wall 1 can be bordered.

-diaphragm-
As the diaphragm 4 used in the bipolar electrolytic cell 50 for alkaline water electrolysis of the present embodiment, an ion permeable diaphragm 4 is used to isolate generated hydrogen gas and oxygen gas while conducting ions. The As the ion permeable diaphragm 4, an ion exchange membrane having ion exchange ability and a porous membrane capable of permeating an electrolytic solution can be used. The ion-permeable diaphragm 4 is preferably one having low gas permeability, high ionic conductivity, low electronic conductivity, and high strength.

-Electrode chamber-
In the bipolar electrolytic cell 50 in the present embodiment, as shown in FIG. 2, an electrode chamber 5 through which an electrolytic solution passes is defined by the partition wall 1, the outer frame 3, and the diaphragm 4.

-gasket-
In the bipolar electrolytic cell 50 for alkaline water electrolysis of this embodiment, it is preferable that the gasket 7 having the diaphragm 4 is sandwiched between the outer frames 3 that border the partition wall 1.
The gasket 7 is used for sealing between the bipolar element 60 and the diaphragm 4 and between the bipolar element 60 against the electrolytic solution and the generated gas. Gas mixing between the bipolar chambers can be prevented.

-Charge carrier-
In the bipolar electrolytic cell 50 for alkaline water electrolysis of the present embodiment, as shown in FIG. 2, the conductive elastic body 2 e and the current collector 2 r are electrically conductive between the cathode 2 c or the anode 2 a and the partition wall 1. The elastic body 2e is provided so as to be sandwiched between the cathode 2c or the anode 2a and the current collector 2r to form an electrolytic holding body.
The charge holding body preferably contains nickel in the base material because it has high durability against alkali, has a redox potential with respect to the anode, and can reduce the anode when electrolysis is stopped. The base may contain at least one selected from nickel oxide, metallic nickel, nickel hydroxide and nickel alloy.

The cathode chamber further includes a conductive elastic body 2e and a current collector 2g, and the conductive elastic body 2e is compressed and accommodated in an electrically connected state between the cathode chamber and the current collector. A part of the cathode current collector may be composed of the charge holding body. Thereby, the increase in the weight of a cell by attaching a charge holding body additionally can be suppressed.

The surface layer of the charge holding body preferably further contains nickel as an element. The surface layer preferably contains at least one selected from the group consisting of nickel oxide, metallic nickel (nickel metal crystal), nickel hydroxide, and the like. The surface layer may include an alloy composed of nickel and another metal. It is particularly preferable that the surface layer is made of metallic nickel. The surface layer may further include at least one selected from the group consisting of titanium, chromium, molybdenum, cobalt, tantalum, zirconium, aluminum, zinc, a platinum group, a rare earth element, and the like.

The method for producing the charge holding member is not particularly limited, and the same production method as that for the anode can be used.

-header-
The bipolar electrolytic cell 50 for alkaline water electrolysis has a cathode chamber 5 c and an anode chamber 5 a for each electrolytic cell 65. In order to continuously perform the electrolysis reaction in the electrolytic cell 50, it is necessary to continue supplying an electrolytic solution sufficiently containing raw materials consumed by electrolysis to the cathode chamber 5c and the anode chamber 5a of each electrolysis cell 65. There is.

The electrolytic cell 65 is connected to an electrolyte supply / discharge pipe called a header 10 common to the plurality of electrolytic cells 65. In general, the anode distribution pipe is called an anode inlet header 10ai, the cathode distribution pipe is called a cathode inlet header 10ci, the anode collection pipe is called an anode outlet header 10ao, and the cathode collection pipe is called a cathode outlet header 10co. The electrolysis cell 65 is connected to each electrode liquid distribution pipe and each electrode liquid collection pipe through a hose or the like.

The material of the header 10 is not particularly limited, but it is necessary to adopt a material that can sufficiently withstand the corrosiveness of the electrolyte used and the operating conditions such as pressure and temperature. The header 10 may be made of iron, nickel, cobalt, PTFE, ETFE, PFA, polyvinyl chloride, polyethylene, or the like.

In the present embodiment, the range of the electrode chamber 5 varies depending on the detailed structure of the outer frame 3 provided at the outer end of the partition wall 1, and the detailed structure of the outer frame 3 depends on the header 10 (electrolysis) attached to the outer frame 3. It may differ depending on the arrangement mode of the pipe for distributing or collecting the liquid. As an arrangement aspect of the header 10 of the bipolar electrolytic cell 50, an internal header 10I type and an external header 10O type are typical.

-Internal header-
The internal header 10I type refers to a type in which the bipolar electrolytic cell 50 and the header 10 (a pipe for distributing or collecting an electrolytic solution) are integrated.

In the internal header 10I type bipolar electrolytic cell 50, more specifically, the anode inlet header 10Iai and the cathode inlet header 10Ici are provided in the lower part in the partition wall 1 and / or the outer frame 3, and The anode outlet header 10Iao and the cathode outlet header 10Ico are provided in the upper part in the partition wall 1 and / or the outer frame 3, and in a direction perpendicular to the partition wall 1. It is provided to extend.

The internal header 10I type bipolar electrolytic cell 50 has an anode inlet header 10Iai, a cathode inlet header 10Ici, an anode outlet header 10Iao, and a cathode outlet header 10Ico, which are collectively referred to as an internal header 10I.

In the example of the internal header 10I type shown in FIGS. 4 and 5, an anode inlet header 10Iai and a cathode inlet header 10Ici are provided in a part of the lower portion of the outer frame 3 at the edge of the partition wall 1. Similarly, an anode outlet header 10Iao and a cathode outlet header 10Ico are provided in a part of the upper frame of the outer frame 3 at the edge of the partition wall 1.

-External header-
The external header 10O type refers to a type in which the bipolar electrolytic cell 50 and the header 10 (a pipe for distributing or collecting an electrolytic solution) are independent.

The external header 10O type bipolar electrolytic cell 50 is independent in such a manner that the anode inlet header 10Oai and the cathode inlet header 10Oci run in parallel with the electrolytic cell 50 in a direction perpendicular to the current-carrying surface of the electrolytic cell 65. Provided. The anode inlet header 10Oai and cathode inlet header 10Oci are connected to each electrolysis cell 65 by a hose.

The anode header 10Oai, the cathode inlet header 10Oci, the anode outlet header 10Oao, and the cathode outlet header 10Oco, which are externally connected to the external header 10O type bipolar electrolytic cell 50, are collectively referred to as the external header 10O. Call.
In the example of the external header 10O type, a luminal member is installed in a through hole for the header 10 provided in a lower portion of the outer frame 3 at the edge of the partition wall 1, and the luminal member is , Connected to the anode inlet header 10Oai and the cathode inlet header 10Oci, and similarly to the through hole for the header 10 provided in the upper portion of the outer frame 3 at the edge of the partition wall 1, A tubular member (for example, a hose or a tube) is installed, and the tubular member is connected to the anode outlet header 10Oao and the cathode outlet header 10Oco.

(Electrolyzer for alkaline water electrolysis)
In FIG. 5, the outline | summary of the electrolyzer for alkaline water electrolysis of this embodiment is shown.
A hydrogen production apparatus with high electrolysis efficiency can be provided by using the bipolar water electrolyzer of the present embodiment as an electrolysis apparatus including other elements and using it as a hydrogen production apparatus.
The electrolytic apparatus for alkaline water electrolysis of this embodiment includes at least the bipolar water electrolysis tank 50 of this embodiment, a gas-liquid separation tank 72 (hydrogen separation tank 72h, oxygen separation tank 72o), electrolyte circulation pump 71, water A charging pump 73 and a rectifier 74 for supplying power for electrolysis are provided.
In addition to the above, the electrolyzer 70 for alkaline water electrolysis of the present embodiment may include an oxygen concentration meter 75, a hydrogen concentration meter 76, a flow meter 77, a pressure gauge 78, a heat exchanger 79, and a pressure control valve 80.

According to the electrolytic apparatus 70 for alkaline water electrolysis of this embodiment, the effect of the bipolar electrolytic cell for alkaline water electrolysis of this embodiment can be obtained.
That is, according to the present embodiment, it becomes possible to realize high-efficiency hydrogen production during operation with a variable power source such as renewable energy, reducing self-discharge that occurs when power supply is stopped, The electric control system can be stabilized. According to the present embodiment, furthermore, it is possible to realize electric power storage with high efficiency, specifically, reduction of pump power and reduction of leakage current.

(Alkaline water electrolysis method)
The alkaline water electrolysis method of the present embodiment can be carried out using the alkaline water electrolysis electrolytic apparatus 70 of the present embodiment.

The alkaline water electrolysis bipolar electrode, the alkaline water electrolysis apparatus, and the alkaline water electrolysis method according to the embodiment of the present invention have been described above with reference to the drawings. The electrolytic cell, the electrolytic apparatus for alkaline water electrolysis, and the alkaline water electrolysis method are not limited to the above examples, and the above embodiment can be appropriately modified.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

A bipolar cell for alkaline water electrolysis and an alkaline water electrolysis apparatus using the same were prepared as follows.

-Bulkhead, outer frame-
As the bipolar element, an element including a partition wall for partitioning the anode and the cathode and an outer frame 3 surrounding the partition wall was used. The materials for the members in contact with the electrolyte such as the partition walls and the frame of the bipolar element were all nickel.

-anode-
Blasting was performed using an expanded nickel opening ratio of 50% as the conductive substrate. The conductive base material was adjusted to a 50 cm square by cutting to obtain an anode sample A.
Anode sample A was immersed in a 5N-HCl aqueous solution for 10 minutes to obtain anode sample B.
Using the anode sample B, the Raney nickel alloy was coated by dispersion plating and immersed in an aqueous NaOH solution of 32 wt% and 80 ° C. for 10 hours to dissolve Al in the Raney nickel alloy. Anode sample C was obtained by the above process.
Anode sample D was prepared by stacking six anode samples C on top of each other and connecting them so as to have the same potential.
Anode sample E was prepared, in which eight anode samples C were stacked one on top of another and connected so as to have the same potential.

Blasting was performed using expanded nickel as the conductive base material. In the same manner as described above, the conductive base material was adjusted to a 50 cm square by cutting to obtain an anode sample A. In the same manner as described above, anode sample A was immersed in 5N-HCl aqueous solution for 10 minutes to obtain anode sample B. Using the anode sample B, the Raney nickel alloy was coated by dispersion plating for 8 times the time of the anode sample C, and immersed in an aqueous NaOH solution of 32 wt% and 80 ° C. for 10 hours to dissolve the Al in the Raney nickel alloy. An anode sample F was obtained by the above process.

((Measurement of anode (oxygen electrode) potential of anode sample))
One anode sample A, B, C, D, E, F was prepared, and a fluororesin beaker was filled with an electrolyte solution of 30 wt% KOH and immersed therein. The temperature of the aqueous solution of KOH was maintained at 90 ° C. An anode sample, a platinum wire mesh (counter electrode), and a fluororesin tube covering the counter electrode. These devices ensure electrical conductivity. The anode sample is oxidized at a current density of 0.4 A / cm ^2. An electric current was applied and hydrogen was generated for 30 minutes. Thereafter, a reduction current of 0.05 A / cm ² was passed, and the change in potential of the anode sample was measured. This potential change was plotted against the total retained charge amount (electric capacity) of the flowing current to obtain an oxidation curve of the anode sample.

Measurement was performed at a temperature of 90 ° C. using a mesh platinum electrode as a counter electrode. As the fluororesin tube, a tube having a large number of holes of 1 mmφ around it was used. The anode potential of the anode sample was measured by a three-electrode method using a Lugin tube in order to eliminate the effect of ohmic loss due to liquid resistance. The distance between the tip of the Lugin tube and the anode was always fixed at 0.05 mm. Silver-silver chloride (Ag / AgCl) was used as a reference electrode for the three-electrode method.

((Measurement of positive retained charge (electric capacity) stored in the anode (oxygen electrode) chamber when oxygen is generated))
In the reduction curve of the anode sample measured for the anode samples A, B, C, D, E, and F, the total charge amount of the current passed until the anode potential became 0 V (vs Ag / AgCl) was generated as oxygen. The positive charge amount (electric capacity) (C / m ² ) sometimes stored in the anode chamber was used.

The positive retained charge amount (electric capacity) of anode sample A was 3667 C / m ² . The positive retained charge amount (electric capacity) of anode sample B was 5018 C / m ² . The positive retained charge amount (electric capacity) of anode sample C was 148610 C / m ² . The positive retained charge amount (electric capacity) of anode sample D was 955350 C / m ² . The positive retained charge amount (electric capacity) of the anode sample E was 1061500 C / m ² . The positive retained charge amount (electric capacity) of the anode sample F was 445830 C / m ² .

The actual specific surface area of each anode sample A, B, C, F per anode was measured. In the anode samples D and E, the actual specific surface area per anode of the anode sample was the same as that of the anode sample C.
The actual specific surface area of the anode sample A was 91 m ² / m ² . The positive actual emergency area of anode sample B was 125 m ² / m ² . The actual specific surface area of the anode sample C was 3700 m ² / m ² . Actual specific surface area of the anode sample F was a 11100m ^² / ^m ^2.

((Specific surface area and pore volume of the first and second pores of the anode catalyst layer))
The specific surface area of the first pore in which the pore diameter of the catalyst layer of the anode is in the range of 2 to 5 nm is 10 ⁻⁵ m ² / g or less for the anode samples A and B, and 1.5 m for the anode samples C, D, and E. ² / g and 4.5 m ² / g for anode sample F.
The pore volume of the first pore is 10 ⁻⁶ ml / g or less for anode samples A and B, 4 × 10 ⁻⁴ ml / g for anode samples C, D and E, and 5 × 10 ⁻⁵ for anode sample F. ml / g.
The specific surface area of the second pore in which the pore diameter of the catalyst layer of the anode is in the range of 0.01 to 2.00 nm is 0.1 m ² / g or less for the anode samples A and B, and for the anode samples C, D, and E. 2.5 m ² / g, was 10.5 m ² / g at the anode sample F.
The pore volume of the second pore was 0.1 ml / g or less for anode samples A and B, 0.1 ml / g for anode samples C, D, and E, and 0.45 ml / g for anode sample F.

((Anode catalyst layer thickness / appearance))
The thickness of the anode catalyst layer was 10 μm or less for anode samples A and B, 200 μm for anode samples C, D, and E, and 1000 μm for anode sample F.
The catalyst layer of the anode contained nickel metal crystals.

-cathode-
A micromesh (wire diameter: 0.1 mm, 50 mesh) active cathode (Pt-based pyrolysis active cathode) was cut into a 50 cm square to produce a cathode.

-Charge carrier (structure)-
Blasting was performed using expanded nickel as the conductive substrate. The conductive substrate was adjusted to 50 cm square by cutting. It was immersed in 5N HCl aqueous solution for 10 minutes. The Raney nickel alloy was coated by dispersion plating and immersed in an aqueous NaOH solution of 32 wt% and 80 ° C. for 10 hours to dissolve Al in the Raney nickel alloy. Through the above process, a structure functioning as an active material was obtained.

The cathode was adjusted to a length of 50 cm × length of 50 cm to obtain a cathode sample G.
The structure was adjusted to 50 cm long by 5.73 cm wide and overlapped with the cathode sample G to obtain a cathode sample A.
The structure was adjusted to a length of 50 cm and a width of 0.73 cm, and overlapped with the cathode sample G to obtain a cathode sample B.
The structure was adjusted to a length of 50 cm and a width of 11.98 cm, and superimposed on the cathode sample G to obtain a cathode sample C.
The structure was adjusted to a length of 50 cm and a width of 18.86 cm, and overlapped with the cathode sample G to obtain a cathode sample D.
The structure was adjusted to a length of 50 cm × width of 50 cm, and three of these layers were overlapped with the cathode sample G to obtain a cathode sample E.
The structure was adjusted to 50 cm in length and 50 cm in width, and four of these were overlaid on the cathode sample G to obtain a cathode sample F.

(Anode and cathode capacitance)
The electric capacity (C / m ² ) of the anode and cathode of the electrolytic cell was measured as follows.

((Measurement of oxidation curve of cathode sample))
One cathode sample A, B, C, D, E, F, and G was prepared, and each was immersed in a fluororesin beaker filled with 30 wt% KOH electrolyte. The temperature of the aqueous solution of KOH was maintained at 90 ° C. A cathode sample, a platinum wire mesh (counter electrode), and a fluororesin tube covering the counter electrode. These devices ensure electrical conductivity. The cathode sample has a current density reduction of 0.4 A / cm ^2. An electric current was applied and hydrogen was generated for 30 minutes. Thereafter, an oxidation current of 0.05 A / cm ² was passed, and the change in potential of the cathode sample was measured. This potential change was plotted against the total charge amount of the flowing current to obtain an oxidation curve of the cathode sample.

Measurement was performed at a temperature of 90 ° C. using a mesh platinum electrode as a counter electrode. As the fluororesin tube, a tube having a large number of holes of 1 mmφ around it was used. The cathode (hydrogen electrode) potential of the cathode sample was measured by a three-electrode method using a Lugin tube in order to eliminate the effect of ohmic loss due to liquid resistance. The distance between the tip of the Lugin tube and the cathode sample was always fixed at 0.05 mm. Silver-silver chloride (Ag / AgCl) was used as a reference electrode for the three-electrode method.

((Measurement of negative retained charge (electric capacity) stored in cathode chamber when hydrogen is generated))
For the cathode samples A, B, C, D, E, F, and G, in the measured oxidation curve of the cathode sample, the total current passed until the cathode potential became −0.8 V (vs Ag / AgCl) The charge amount was defined as the negative retained charge amount (electric capacity) stored in the cathode chamber when hydrogen was generated.

The negative retained charge amount (electric capacity) of the cathode sample A was 48250 C / m ² . The negative retained charge amount (electric capacity) of the cathode sample B was 9650 C / m ² . The negative retained charge amount (electric capacity) of the cathode sample C was 96500 C / m ² . The negative retained charge amount (electric capacity) of the cathode sample D was 149575 C / m ² . The negative retained charge amount (electric capacity) of the cathode sample E was 868500 C / m ² . The negative retained charge amount (electric capacity) of the cathode sample F was 1158000 C / m ² . The negative retained charge amount (electric capacity) of the cathode sample G was 3956.5 C / m ² .

The electrolytic cell used in this example is an electrolytic cell including a cathode chamber having a cathode, an anode chamber having an anode, a diaphragm partitioning the cathode chamber and the anode chamber, and an electrolyte filled in the cathode chamber and the anode chamber. It was supposed to be equipped with. The electrolysis cell was provided with a cathode chamber having a cathode, an anode chamber having an anode, and a diaphragm partitioning the cathode chamber and the anode chamber. The cathode chamber and the anode chamber were arranged to face each other with a diaphragm interposed therebetween. The cathode chamber and the anode chamber were each filled with an electrolytic solution. As the cathode, the anode, the diaphragm, and the electrolyte, known materials used in water electrolysis were used.

-diaphragm-
A membrane sample prepared by cutting a polysulfone-based porous membrane into a 50 cm square by cutting.

-Bipolar electrolytic cell, Bipolar element-
49 pieces of bipolar elements are used, and as shown in FIG. 1, a fast head, an insulating plate and an anode terminal unit are arranged on one end side, and further, an anode side gasket part, a diaphragm, a cathode side gasket part, Forty-nine pairs of bipolar elements arranged in this order were arranged, and further, an anode side gasket portion, a diaphragm, and a cathode side gasket portion were arranged to assemble a bipolar electrolytic cell.
In this example, the cathode chamber and the anode chamber had 50 pairs of series connection structures each having 50 chambers.

-gasket-
As the gasket, a material made of EPDM rubber was used.

-Header, conduit-
An external header type bipolar element was adopted.
As shown in FIG. 4, in the bipolar electrolytic cell 50 of this embodiment, a conduit 20 (anode distribution tube 20Oai) for distributing and collecting the electrolytic solution is provided outside the casing of the electrolytic cell 50. , Cathode liquid distribution pipe 20Oci, anode liquid collection pipe 20Oao, and cathode liquid collection pipe 20Oco). Furthermore, in this electrolytic cell 50, hoses (anode inlet header 10Oai, cathode inlet header 10Oci, anode outlet header 10Oao, cathode outlet header 10Oco) as headers 10 for passing the electrolytic solution from these conduits 20 to the electrode chamber 5 are provided. Installed from outside.
Here, as shown in FIG. 4, all of the headers 10 (the anode inlet header 10Oai, the cathode inlet header 10Oci, the anode outlet header 10Oao, the cathode outlet header 10Oco) are seen from the side of the partition wall 1 of the bipolar element 60. Arranged to extend outward. As shown in FIG. 4, any of the conduits 20 (anode distribution pipe 20Oai, cathode distribution pipe 20Oci, anode collection pipe 20Oao, cathode collection pipe 20Oco) is a bipolar element 60. It was arranged so as to extend in a direction perpendicular to the partition wall 1.
In this way, an electrolytic cell 50 of the external header 10O type was produced.
The electrolyte was flowed to the cathode chamber 5c via the cathode inlet header 10Oci and from the cathode chamber 5c via the cathode outlet header 10Oco. Further, the electrolytic solution was allowed to flow from the anode chamber 5a to the anode chamber 5a via the anode inlet header 10Oai via the anode outlet header 10Oco.
As shown in FIG. 4, the inlet hose is on one end of the lower side of the rectangular outer frame 3 in plan view, and the outlet hose is on the upper side of the side connected to the other end of the lower side of the rectangular outer frame 3 in plan view. , Each connected. Here, the inlet hose and the outlet hose were provided so as to face each other across the central portion of the electrode chamber 5 in the rectangular electrode chamber 5 in plan view. The electrolyte flowed from below to above while tilting with respect to the vertical direction, and rose along the electrode surface.
In the bipolar electrolytic cell 50 of this embodiment, the electrolyte flows into the anode chamber 5a and the cathode chamber 5c from the inlet hose of the anode chamber 5a and the cathode chamber 5c, and from the outlet hose of the anode chamber 5a and the cathode chamber 5c. The electrolytic solution and the generated gas flow out of the electrolytic cell 50.
In the cathode chamber 5c, hydrogen gas is generated by electrolysis, and in the anode chamber 5a, oxygen gas is generated by electrolysis. Therefore, in the cathode outlet header 10Oco described above, a mixed phase flow of the electrolyte and hydrogen gas results, and the anode outlet header At 10 Oao, a mixed phase flow of electrolyte and oxygen gas was obtained.

Example 1
The bipolar electrolytic cell of Example 1 was produced by the following procedure.

The cathode element A attached to the cathode face of the bipolar electrode frame and the anode sample C attached to the anode face of the bipolar element frame were designated as bipolar elements. Moreover, what attached the cathode sample A to the flame | frame of the cathode terminal element was made into the cathode terminal element. An anode terminal element was prepared by attaching the anode sample C to the frame of the anode terminal element.

The area S1 of the electrodes (anode and cathode) attached to the bipolar element was adjusted to 0.25 m ² .
The cross-sectional area S2 of the flow path of the header (anode inlet header, anode outlet header, cathode inlet header, cathode outlet header) provided on the side of the outer frame was adjusted to 2.83 × 10 ⁻⁵ m ² .
The length L2 of the header channel was adjusted to 0.5 m ² .

Also, the thickness d of the bipolar element was adjusted to 33 mm. Moreover, the thickness of the cathode terminal element and the anode terminal element was adjusted to 0.0125 m.

49 pieces of the above bipolar elements were prepared. Moreover, the said cathode terminal element and the said anode terminal element were prepared one each.

ガスケット Gaskets were affixed to the metal frame portions of all bipolar elements, cathode terminal elements, and anode terminal electrolytic cell elements.

A single diaphragm sample was sandwiched between the anode terminal element and the cathode side of the bipolar element. Forty-eight 49-pole elements are arranged in series so that one anode side and the other cathode side of the adjacent bipolar elements face each other, and 48 sheets are arranged between adjacent bipolar elements. Each membrane sample was sandwiched one by one. Further, one diaphragm sample was sandwiched between the anode side of the 49th bipolar element and the cathode terminal element. A bipolar electrolyzer of Example 1 was obtained by using a fast head, an insulating plate, and a loose head, and tightening them with a press.

A 30% aqueous KOH solution was used as the electrolytic solution.
With the electrolyte circulation pump, circulation of the anode chamber, oxygen separation tank (gas-liquid separation tank for anode) and anode chamber, and circulation of the cathode chamber, hydrogen separation tank (cathode gas-liquid separation tank) and cathode chamber, went.
The temperature of the electrolytic solution was adjusted to 90 ° C.

A current was passed from the rectifier to the bipolar electrolytic cell so that the current was 6 kA / m ² with respect to the area S1 of each cathode and anode. In Example 1, since the area S1 of the electrode is 500 mm × 500 mm, 1.5 kA was energized from the rectifier to the bipolar electrolytic cell.

The pressure in the electrolytic cell was measured with a pressure gauge, and electrolysis was performed while adjusting the cathode side pressure to 50 kPa and the oxygen side pressure to 49 kPa. The pressure adjustment was performed by a pressure control valve installed downstream of the pressure gauge.

And the alkaline water electrolysis in Example 1 was evaluated as follows.

(Electrolysis test)
Water electrolysis was performed by energizing continuously at a current density of 6 kA / m ² for 8 hours. The cell voltage V of the electrolytic cell was measured, and the arithmetic average value (V) of the electrolytic cell was obtained by calculation.

(Potential holding time)
After energizing continuously for 7 hours at a current density of 6 kA / m ² , the rectifier was turned off and the cell voltage V was continuously measured. Based on the time immediately after the stop of electrolysis, the time during which the arithmetic average of the cell voltage V was maintained at 1 V or more was defined as the potential holding time T (hour).

(Manufacturability)
The productivity of the electrolytic cell was evaluated according to the following evaluation criteria. The results are shown in Table 1.
<Evaluation criteria>
○ (Excellent): The number of welding points necessary for fixing the electrode to the electrolytic cell is less than 500 / m ² Δ (Good): The number of welding points necessary for fixing the electrode to the electrolytic cell is 500 / m ² or more Less than 1500 locations / m ² × (defect): The number of welding points necessary for fixing the electrode to the electrolytic cell is 1500 locations / m ² or more.

(Example 2)
A bipolar electrolytic cell and an electrolytic apparatus for alkaline water electrolysis were produced in the same manner as in Example 1 except that L2 was adjusted to 1 m. Detailed conditions and results are shown in Table 1.

(Example 3)
A bipolar electrode electrolytic cell and an electrolytic apparatus for alkaline water electrolysis were prepared in the same manner as in Example 1 except that the cathode sample was the cathode sample B, S1 was adjusted to 2.7 m ² , and L2 was adjusted to 2.4 m. Detailed conditions and results are shown in Table 1.

Example 4
A bipolar electrolytic cell and an electrolytic device for alkaline water electrolysis were produced in the same manner as in Example 1 except that S1 was adjusted to 2.7 m ² and L2 was adjusted to 2.4 m. Detailed conditions and results are shown in Table 1.

(Example 5)
A bipolar electrolytic cell and an electrolytic apparatus for alkaline water electrolysis were produced in the same manner as in Example 1 except that S1 was adjusted to 2.7 m ² and L2 was adjusted to 6.5 m. Detailed conditions and results are shown in Table 1.

(Example 6)
A bipolar electrolytic cell and an electrolytic apparatus for alkaline water electrolysis were produced in the same manner as in Example 1 except that L2 was adjusted to 0.2 m. Detailed conditions and results are shown in Table 1.

(Example 7)
A bipolar electrolytic cell and an electrolytic apparatus for alkaline water electrolysis were prepared in the same manner as in Example 1 except that the cathode sample E was used as the cathode sample. Detailed conditions and results are shown in Table 1.

(Example 8)
A bipolar electrolytic cell and an electrolytic apparatus for alkaline water electrolysis were produced in the same manner as in Example 1 except that S1 was adjusted to 2.7 m ² and L2 was adjusted to 7.2 m. Detailed conditions and results are shown in Table 1.

Example 9
A bipolar electrolytic cell and an electrolytic apparatus for alkaline water electrolysis were prepared in the same manner as in Example 1 except that S2 was adjusted to 7.85 × 10 ⁻⁷ m ² and L2 was adjusted to 2.4 m. Detailed conditions and results are shown in Table 1.

(Example 10)
A bipolar electrolytic cell and an electrolytic apparatus for alkaline water electrolysis were prepared in the same manner as in Example 1 except that the cathode sample was the cathode sample C and S2 was adjusted to 7.85 × 10 ⁻⁷ m ² . Detailed conditions and results are shown in Table 1.

(Example 11)
A bipolar electrode electrolytic cell and an electrolytic apparatus for alkaline water electrolysis were prepared in the same manner as in Example 1 except that the anode sample was anode sample B, S2 was adjusted to 1.77 × 10 ⁻⁶ m ² , and L2 was adjusted to 1 m. Produced. Detailed conditions and results are shown in Table 1.

(Example 12)
A bipolar electrolytic cell and an electrolytic apparatus for alkaline water electrolysis were prepared in the same manner as in Example 1 except that the anode sample was the anode sample D, the cathode sample was the cathode sample D, and L2 was adjusted to 1 m. Detailed conditions and results are shown in Table 1.

(Example 13)
A bipolar electrolytic cell and an electrolytic apparatus for alkaline water electrolysis were produced in the same manner as in Example 1 except that L2 was adjusted to 1 m and the number of stacks was set to 100. Detailed conditions and results are shown in Table 1.

(Example 14)
A bipolar electrolytic cell and an electrolysis apparatus were produced in the same manner as in Example 1 except that the anode sample was changed to the anode sample F. Detailed conditions and results are shown in Table 1.

(Comparative Example 1)
A bipolar electrolytic cell and an electrolytic apparatus for alkaline water electrolysis were produced in the same manner as in Example 1 except that the cathode sample F was used as the cathode sample. Detailed conditions and results are shown in Table 1.

(Comparative Example 2)
A bipolar electrolytic cell and an electrolytic device for alkaline water electrolysis were prepared in the same manner as in Example 1 except that the cathode sample was changed to the cathode sample G. Detailed conditions and results are shown in Table 1.

(Comparative Example 3)
A bipolar electrolytic cell and an electrolytic apparatus for alkaline water electrolysis were prepared in the same manner as in Example 1 except that the anode sample was Anode Sample A and the cathode structure sample was Cathode Sample C. Detailed conditions and results are shown in Table 1.

(Comparative Example 4)
A bipolar electrode electrolytic cell and an electrolytic apparatus for alkaline water electrolysis were prepared in the same manner as in Example 1 except that the cathode sample was the cathode sample G, S1 was adjusted to 2.7 m ² , and L2 was adjusted to 2.4 m. Detailed conditions and results are shown in Table 1.

(Comparative Example 5)
A bipolar electrolytic cell and an electrolytic device were produced in the same manner as in Example 1 except that the anode sample was changed to the anode sample E. Detailed conditions and results are shown in Table 1.

In Examples 1 to 14, electrolysis was possible at 1.85 V or less and the potential holding time was 3 hours or more, which was a sufficiently stable result for system control. Further, in Examples 1 to 13 in which the actual electrode surface area of the anode was 10,000 m ² / m ² or less, the cell voltage could be further reduced. In particular, the electrolytic cells of Examples 2, 4, and 7 are excellent.
On the other hand, Comparative Examples 1, 3 and 5 have poor electrolysis efficiency, and Comparative Examples 2 to 4 have a short potential holding time, which can be achieved with variable power sources such as renewable energy such as wind power and sunlight. In operation, it has been shown that there are practical problems in using the electrolytic cell as an emergency storage battery when power supply is stopped and in order to stably operate the electric control system even in an emergency.

According to the present invention, during operation with a variable power source such as renewable energy, it is possible to store a large amount of electricity for a long period of time and to transport over a long distance, and to stabilize the electric control system when the power supply is stopped.

1 partition 2 electrode 2a anode 2c cathode 2e conductive elastic body 2r current collector 3 outer frame 4 diaphragm 5 electrode chamber 5a anode chamber 5c cathode chamber 5i electrolyte inlet 5o electrolyte outlet 5ai anode electrolyte inlet 5ao anode electrolyte outlet 5ci Cathode electrolyte inlet 5co Cathode electrolyte outlet 6 Rectifier plate 6a Anode rectifier plate (anode rib)
6c Cathode current plate (cathode rib)
7 Gasket 10 Header 10I Internal header 10O External header 10Oai Anode inlet header (anode inlet side hose)
10Oao anode outlet header (anode outlet hose)
10Oci cathode inlet header (cathode inlet hose)
10Oco cathode outlet header (cathode outlet hose)
20 Conduit 20 Oai Anode distribution tube 20 Oao Anode collection tube 20 Oci Cathode distribution tube 20 Oco Cathode collection tube 50 Bipolar electrolytic cell 51 g Fast head, loose head 51 a Anode terminal element 51 c Cathode terminal element 51 i Insulating plate 51 r Tie rod 60 Bipolar element 65 Electrolysis cell 70 Electrolysis device 71 Electrolyte circulation pump 72 Gas-liquid separation tank 72h Hydrogen separation tank 72o Oxygen separation tank 73 Water supply pump 74 Rectifier 75 Oxygen concentration meter 76 Hydrogen concentration meter 77 Flow meter 78 Pressure meter 79 Heat exchanger 80 Pressure control valve D1 A given direction along the bulkhead (electrolyte passage direction)
S1 Area of current-carrying surface of bipolar element S2 Cross-sectional area of header channel L2 Length of header channel Z Zero gap structure d Electrolytic cell thickness

Claims

A plurality of bipolar elements each including an anode, a cathode, a partition wall that separates the anode and the cathode, and an outer frame that borders the partition wall are stacked with a diaphragm interposed therebetween, and are disposed outward of the outer frame. A bipolar electrolytic cell comprising a header communicating with an electrode chamber defined by the partition wall, the outer frame, and the diaphragm;
The electric capacity of the anode is in the range of 4825 C / m 2 to 965000 C / m 2 , and the electric capacity of the cathode is in the range of 4825 C / m 2 to 965000 C / m 2 .
A bipolar electrolytic cell characterized by that.
A plurality of bipolar elements each including an anode, a cathode, a partition wall that separates the anode and the cathode, and an outer frame that borders the partition wall are stacked with a diaphragm interposed therebetween, and are disposed outward of the outer frame. A bipolar electrolytic cell comprising a header communicating with an electrode chamber defined by the partition wall, the outer frame, and the diaphragm;
The electric capacity of the anode is in the range of 4825 C / m 2 to 965000 C / m 2 , and the electric capacity of the cathode is in the range of 4825 C / m 2 to 965000 C / m 2 .
A bipolar electrolytic cell for alkaline water electrolysis.
When the area of the current-carrying surface of the bipolar element is S1, the sectional area of the header channel is S2, and the length of the header channel is L2, (S2 / S1) / L2 is 1.5. 3. The bipolar electrolytic cell according to claim 1, wherein the electrolytic cell is in the range of × 10 −6 m −1 to 2.3 × 10 −4 m −1 .
The bipolar electrolytic cell according to any one of claims 1 to 3, wherein a lower one of the electric capacity of the anode and the electric capacity of the cathode is in a range of 9650 C / m 2 to 955350 C / m 2 .
The bipolar electrolytic cell according to any one of claims 1 to 4, wherein an electric capacity of the anode is larger than an electric capacity of the cathode.
The bipolar electrolytic cell according to claim 5, wherein the electric capacity of the cathode exceeds 0.1 times the electric capacity of the anode and is 0.99 times or less.
The bipolar electrolytic cell according to claim 5 or 6, wherein the electric capacity of the cathode exceeds 0.1 times the electric capacity of the anode and is 0.49 times or less.
The bipolar electrolytic cell according to any one of claims 1 to 7, wherein an actual electrode surface area per 1 m 2 of geometric cell area of the anode is in a range of 90 m 2 to 10000 m 2 .
The bipolar electrolytic cell according to any one of claims 1 to 8, which has 50 to 500 bipolar elements.
The bipolar electrolytic cell according to any one of claims 2 to 9, wherein the S1 is 0.1 m 2 to 10 m 2 .
The bipolar electrolytic cell according to any one of claims 2 to 10, wherein the thickness d of the electrolytic cell is 10 mm to 100 mm.
The bipolar electrolytic cell according to any one of claims 1 to 11, wherein the anode contains at least one nickel compound selected from the group consisting of nickel oxide, metallic nickel, nickel hydroxide, and a nickel alloy.
The anode has a conductive substrate and a catalyst layer disposed on the conductive substrate;
The catalyst layer contains nickel metal crystals and has pores;
Of the pores of the catalyst layer,
The specific surface area of the first pores having a pore diameter in the range of 2 to 5 nm is 0.6 to 2.0 m 2 / g,
The pore volume of the first pore is 3 × 10 −4 to 9 × 10 −4 ml / g,
Of the pores, the specific surface area of the second pores having a pore diameter in the range of 0.01 to 2.00 μm is 2.0 to 5.0 m 2 / g,
The pore volume of the second pore is 0.04 to 0.2 ml / g,
The catalyst layer has a thickness of 50 to 800 μm.
The bipolar electrolytic cell according to any one of claims 1 to 12.
The cathode is at least one Pt group selected from the group consisting of Ru—La—Pt, Ru—Ce, Pt—Ce, and Pt—Ir, Ir—Pt—Pd, and Pt—Ni. The bipolar electrolytic cell according to any one of claims 1 to 13, comprising a compound.
The structure of the cathode and the anode has a catalyst layer on the surface of the conductive substrate, and the conductive substrate is at least selected from the group consisting of metallic nickel, nickel oxide, nickel hydroxide, and nickel alloy. The bipolar electrolytic cell according to claim 14, comprising a kind of nickel compound.
The bipolar electrolytic cell according to any one of claims 1 to 15, wherein the cathode and the anode have a mesh structure.
The compound according to any one of claims 1 to 16, wherein the cathode base material has a wire diameter in the range of 0.05 mm to 0.5 mm, and the aperture has a range of 30 mesh to 80 mesh. Polar electrolytic cell.
The bipolar electrolytic cell according to any one of claims 1 to 17, wherein the anode base material has a mesh structure having an opening ratio in a range of 20% to 60%.
The bipolar electrolytic cell according to any one of claims 1 to 18, wherein electrolysis cells are electrically connected in series.
The cathode, the anode, the diaphragm, and a bipolar element having a partition partitioning the anode chamber and the cathode chamber, the diaphragm is located between the cathode and the anode, and the diaphragm is in contact with the cathode and the anode The bipolar water electrolyzer according to claim 19.
A bipolar electrolytic cell according to any one of claims 1 to 20, an electrolytic solution circulation pump for circulating an electrolytic solution, a gas-liquid separation tank for separating the electrolytic solution from hydrogen and / or oxygen, An electrolyzer comprising a water input pump for replenishing water.
The electrolyzer according to claim 21, further comprising a detector that detects a stop of power supply when power supply to the electrolyzer is stopped, and a controller that automatically stops the electrolyte circulation pump.
23. A water electrolysis method, wherein the electrolyte circulation pump is stopped when power supply to the electrolyzer according to claim 21 or 22 is stopped.
In a hydrogen production method for producing hydrogen by electrolyzing water containing an alkali with an electrolytic cell,
The electrolytic cell includes a plurality of bipolar elements each including an anode, a cathode, a partition wall that separates the anode and the cathode, and an outer frame that borders the partition wall, with a diaphragm interposed therebetween. A bipolar electrolytic cell having a header communicating with an electrode chamber defined by the partition wall, the outer frame, and the diaphragm outside the frame, and the electric capacity of the anode is 4825 C / m 2 to 965000 C / M 2 , and the electric capacity of the cathode is in the range of 4825 C / m 2 to 965000 C / m 2 .