Electrode, anode for water electrolysis, electrolytic cell, and method for producing hydrogen

Abstract

To provide an electrode with low overpotential of oxygen evolution and high abrasion durability, an anode for water electrolysis, a bipolar electrolysis cell using the anode for water electrolysis, and a production method of hydrogen using the anode for water electrolysis.SOLUTION: An electrode includes LaNixMyO3-z (x+y is 0.8 or more and 1.2 or less, y is 0.005 or more and 0.2 or less, z is -0.5 or more and 0.5 or less, and M includes at least one of Nb, Ta, Sb, Ti, Mn, and Zr) on a substrate. In a LaNixMyO3-z layer cross-section, the variation coefficient of inscribed-circle diameter distribution is 0.2 or more and 0.6 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an electrode, an anode for water electrolysis, a bipolar electrolytic cell using the anode for water electrolysis, and a method for producing hydrogen using the anode for water electrolysis. [Background technology]

[0002] In recent years, hydrogen produced using renewable energy has been attracting attention as a clean energy source that can solve problems such as global warming caused by CO2 and dwindling fossil fuel reserves. Hydrogen production using renewable energy is required to be as inexpensive as hydrogen production by conventional reforming of fossil fuels. Therefore, hydrogen production using renewable energy requires high levels of energy efficiency and inexpensive equipment that could not be achieved with conventional technologies.

[0003] One method of producing hydrogen that can meet the above requirements is the electrolytic decomposition of water (water electrolysis). For example, several ideas have been proposed for producing hydrogen by water electrolysis using power generated by natural energy sources such as wind or solar power, and then storing or transporting the hydrogen. In water electrolysis, oxygen is generated at the anode and hydrogen is generated at the cathode by passing an electric current through the water. The main cause of energy loss in electrolysis is the overvoltage of the anode and cathode. Reducing this overvoltage makes it possible to produce hydrogen efficiently. In particular, the overvoltage of the anode is higher than the overvoltage of the cathode, and research and development into reducing the overvoltage of the anode is being widely pursued.

[0004] Among oxides having a perovskite structure, some are known to have high oxygen generating capacity and have attracted attention as anode materials for water electrolysis (Non-Patent Document 1). To use an oxide having a perovskite structure as an anode for alkaline water electrolysis, one method involves forming an oxide layer on the surface of a conductive substrate. For example, Patent Document 1 discloses a water electrolysis anode that has low oxygen overvoltage and high durability by forming a metal oxide layer with a high content of perovskite oxide in the crystalline components on the surface of a nickel porous substrate, and a water electrolysis device using the anode. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2018 / 155503 [Non-patent literature]

[0006] [Non-Patent Document 1] Science,2011,334,1383 Summary of the Invention [Problem to be solved by the invention]

[0007] It was found that the anode described in Patent Document 1 has a problem in that the oxygen overvoltage tends to increase after an ultrasonic erosion test, and it is susceptible to the effects of depletion.

[0008] The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrode that exhibits a low oxygen evolution overvoltage even after an ultrasonic erosion test and is less susceptible to depletion, an anode for water electrolysis, a bipolar electrolytic cell using the anode for water electrolysis, and a method for producing hydrogen using the anode for water electrolysis. [Means for solving the problem]

[0009] The present inventors have conducted extensive research and experiments to solve the above problems. As a result, they have found that a LaNi x M y O 3-z The inventors have found that an electrode on which a layer is formed has a low overvoltage for oxygen evolution even after an ultrasonic erosion test and is therefore usable as an anode for water electrolysis that is less susceptible to wear, leading to the present invention.

[0010] That is, the present invention is as follows. [1] On the substrate, LaNi x M y O 3-z (x+y is 0.8 or more and 1.2 or less, y is 0.005 or more and 0.2 or less, z is -0.5 or more and 0.5 or less, and M contains at least one of Nb, Ta, Sb, Ti, Mn, and Zr), and LaNi x M y O 3-z An electrode characterized in that the coefficient of variation of the inscribed circle diameter distribution in the layer cross section is 0.2 or more and 0.6 or less. [2] The electrode according to claim 1, wherein the maximum value of the inscribed circle diameter is 150 μm or more and 400 μm or less. [3] The electrode according to claim 1 or 2, wherein the proportion of inscribed circle diameters of 100 μm or less is 40% or less in the distribution of the inscribed circle diameters. [4] An electrolytic cell, characterized by using the electrode according to any one of [1] to [3] as an anode. [5] A method for producing hydrogen by electrolyzing alkali-containing water in an electrolytic cell, the electrolytic cell having at least an anode and a cathode, the anode having a substrate on which LaNi x M y O 3-z (x+y is 0.8 or more and 1.2 or less, y is 0.005 or more and 0.2 or less, z is -0.5 or more and 0.5 or less, and M contains at least one of Nb, Ta, Sb, Ti, Mn, and Zr), and LaNi x M y O 3-z A method for producing hydrogen, characterized in that the coefficient of variation of the inscribed circle diameter distribution in a layer cross section is 0.2 or more and 0.6 or less. [Effects of the Invention]

[0011] According to the present invention, it is possible to obtain an electrode that is less susceptible to wear and has a low oxygen overvoltage, an anode for water electrolysis, and a water electrolysis cell including the anode for water electrolysis. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a side view showing an example of an entire electrolytic cell including an electrolytic cell equipped with the electrode of the present embodiment as an anode. [Figure 2] FIG. 2 is a diagram showing a cross section of the inside of an electrolytic cell in the part enclosed by the dashed square frame in FIG. 1 in an example of an electrolytic cell including an electrolytic cell equipped with the electrode of the present embodiment as an anode. [Figure 3] FIG. 1 is a diagram showing an outline of an electrolysis device used in Examples and Comparative Examples. [Figure 4] FIG. 1 is a diagram showing an outline of a bipolar electrolytic cell used in an electrolysis test. [Figure 5] 1 is an example of a cross-sectional photograph of an electrode. [Figure 6] This is an example of an image obtained by cutting out a region consisting only of the electrode cross section and the embedding resin from Figure 5. [Figure 7] This is an image obtained by extracting the catalyst layer from Figure 6 through binarization. [Figure 8] This is the image obtained by performing Dilate and Erode processing on the image in Figure 7. [Figure 9] 10 is an example of a diagram of the Filename_Tb.Th(G) window. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a mode for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. Note that the following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention. Furthermore, the present invention can be modified in various ways without departing from the gist of the present invention.

[0014] (electrode) In this embodiment, the electrode is primarily characterized by having at least a substrate.

[0015] The substrate is preferably conductive. Examples of the material of the conductive substrate include nickel, materials containing nickel as a main component, titanium, GC (glassy carbon), tantalum, zirconium, gold, platinum, and palladium. Examples of materials containing nickel as a main component include nickel-based alloys such as Monel, Inconel, and Hastelloy.

[0016] From the viewpoint of heat resistance in the firing step during electrode preparation, the material of the substrate is more preferably a metal, and furthermore, nickel or a material containing nickel as a main component is even more preferred from the viewpoints of durability, conductivity, and economy, as these metals are not dissolved even at the oxygen generating potential in an alkaline aqueous solution and are available at lower cost than noble metals.

[0017] The conductive substrate of the electrode may be flat or may be a porous body having a plate shape with numerous holes. Specific examples of the porous body include expanded metal, punched metal, plain woven mesh, foam metal, and similar shapes. Among these, expanded metal is preferred. While its dimensions are not particularly limited, in order to achieve both an increase in the amount of gas generated by increasing the electrolysis surface area and efficient removal of gas generated by electrolysis from the electrode surface, and from the viewpoint of mechanical strength, it is preferred that the mesh have a center-to-center distance (SW) of 2 mm to 5 mm, a center-to-center distance (LW) of 3 mm to 10 mm, a thickness of 0.2 mm to 2 mm, and an aperture ratio of 20% to 80%. More preferably, SW is 3 mm to 4 mm, LW is 4 mm to 6 mm, a thickness of 0.8 mm to 1.5 mm, and an aperture ratio of 40% to 60%.

[0018] In this embodiment, LaNi x Nb y O 3-zThe second characteristic is that LaNi has the following properties: (x + y is 0.8 or more and 1.2 or less, y is 0 or more and 0.2 or less, z is -0.5 or more and 0.5 or less). x Nb y O 3-z is deposited directly on the substrate, and LaNi x Nb y O 3-z The substrate and the LaNi x Nb y O 3-z An interface may be formed between the layers.

[0019] In this embodiment, a high oxygen generating capacity can be achieved by disposing Ni in at least a part of the B site of a metal oxide having a perovskite structure. Furthermore, disposing Nb in the B site together with Ni is preferable because it can provide a low oxygen generating overvoltage.

[0020] From the viewpoint of providing a low oxygen evolution overvoltage, x+y is 0.8 or more and 1.2 or less, more preferably 0.8 or more and 1.05 or less, and even more preferably 1.0 or more and 1.05 or less. y is 0 or more and 0.2 or less, preferably 0.005 or more and 0.15 or less, and more preferably 0.01 or more and 0.1 or less. z is -0.5 or more and 0.5 or less. In the present invention, z is determined by the composition ratio 3-z of O, which is calculated so that the valence balance of the composition formula is balanced, assuming that La is trivalent, Ni is trivalent, Nb is pentavalent, and O is -2valent. For example, in the composition formula LaNi x Nb y O 3-z If x=0.8 and y=0.2, then z=-0.2 can be calculated from the equation 3-z=(3+3×0.8+5×0.2) / 2.

[0021] On the substrate, LaNi x Nb y O 3-z (x+y is 0.8 or more and 1.2 or less, y is 0 or more and 0.2 or less, z is -0.5 or more and 0.5 or less) can be used to, for example, x Nb yO 3-z The layer is peeled off and dissolved in aqua regia, and the composition is analyzed by ICP-AES (inductively coupled plasma atomic emission spectroscopy). x Nb y O 3-z The layer is peeled off and the composition is analyzed using an X-ray fluorescence analyzer. x Nb y O 3-z This can be confirmed by a known method such as SEM-EDX analysis of the layer.

[0022] In this embodiment, LaNi x M y O 3-z The third characteristic is that the coefficient of variation of the inscribed circle diameter distribution in the layer cross section is 0.2 or more and 0.6 or less.

[0023] In this embodiment, LaNi x M y O 3-z The inscribed circle diameter distribution of the layer cross section was measured by embedding a small piece of the electrode in epoxy resin, cutting and polishing it to prepare a cross section observation sample, and then observing it with an electron microscope at a magnification of 50 times. The backscattered electron image was used to extract the diameter of the inscribed circle of the catalyst layer, LaNi, using image processing software. x M y O 3-z The cross section of the electrode consisting of the layer and the substrate and the area containing only the embedding resin were cut out with a width of 2540 μm, and the cut-out image was processed to obtain the LaNi x M y O 3-z After binarizing and extracting the layer, LaNi x M y O 3-z After image processing to fill the voids in the layer, the image of the filled LaNi x M y O 3-z This is done by calculating the diameter distribution of the inscribed circle of the layer. When processing an image, it is preferable to perform a filter process as appropriate to remove noise. A specific method for image processing will be described later in the examples.

[0024] The inscribed circle diameter distribution obtained in this way is x M y O 3-z The coefficient of variation, calculated by dividing the standard deviation of the inscribed circle diameter distribution by the average value, is x M y O 3-z The smaller the coefficient of variation, the more uniform the LaNi x M y O 3-z The layer thickness is uniform.

[0025] The present inventors have prepared a LaNi x M y O 3-z (x+y is 0.8 or more and 1.2 or less, y is 0.005 or more and 0.2 or less, z is -0.5 or more and 0.5 or less, and M contains at least one of Nb, Ta, Sb, Ti, Mn, and Zr), and LaNi x M y O 3-z It was surprisingly found that electrodes with a coefficient of variation of the inscribed circle diameter distribution of 0.2 to 0.6 in the layer cross section had low oxygen overvoltage even after the erosion test. x M y O 3-z When the coefficient of variation of the inscribed circle diameter distribution of the layer cross section is 0.2 or more and 0.6 or less, the film thickness distribution is constant, so that the catalyst layer LaNi x M y O 3-z This is thought to be because the substrate is not exposed even when the layer is worn away, and therefore the oxygen overvoltage does not increase significantly. In order to provide a low oxygen evolution overvoltage even after the erosion test, the coefficient of variation of the inscribed circle diameter distribution is 0.2 or more and 0.6 or less. When the coefficient of variation is 0.2 or more, LaNi x M y O 3-z Since there is a moderate distribution in the layer thickness, cracks and peeling are unlikely to occur during preparation, which is excellent from the viewpoint of productivity. x M y O 3-zThe layer thickness becomes uniform, and the substrate is less likely to be exposed even if it is worn away by an ultrasonic erosion test. LaNi x M y O 3-z The coefficient of variation of the inscribed circle diameter distribution of the layer cross section is preferably 0.2 to 0.55, more preferably 0.2 to 0.5, and most preferably 0.25 to 0.5. The lower limit of the coefficient of variation may be 0.3 or more, and the upper limit may be 0.45 or less.

[0026] In this embodiment, it is preferable that the maximum value of the inscribed circle diameter is 150 μm or more and 400 μm or less, since this reduces the overvoltage for oxygen generation after an ultrasonic erosion test. A specific method for calculating the maximum value of the inscribed circle diameter will be described later in the Examples section. The maximum value of the inscribed circle diameter is more preferably 175 μm or more and 350 μm or less, and even more preferably 200 μm or more and 300 μm or less, from the viewpoint of reducing the oxygen overvoltage after an erosion test.

[0027] In this embodiment, it is preferable that the proportion of inscribed circle diameters of 100 μm or less is 3% or more and 40% or less in the inscribed circle diameter distribution, since this reduces the oxygen overvoltage after an ultrasonic erosion test. A specific method for calculating the proportion of inscribed circle diameters of 100 μm or less in the inscribed circle diameter distribution will be described later in the Examples section. The proportion of inscribed circle diameters of 100 μm or less in the inscribed circle diameter distribution is more preferably 3% or more and 35% or less, and even more preferably 3% or more and 30% or less, from the viewpoint of reducing the oxygen overvoltage after an erosion test. The lower limit of the proportion is preferably smaller, and is preferably 1% or more, or even 2% or more.

[0028] The electrode of the present embodiment can be put to practical use as an anode for water electrolysis, and it is possible to provide an electrolytic cell for water electrolysis using the electrode of the present embodiment as an anode, and a method for producing hydrogen using the anode for water electrolysis. Water containing alkali may be used for water electrolysis.

[0029] (Electrode preparation method) The electrode of this embodiment is prepared by applying an aqueous solution (coating liquid) containing metal salts of La, Ni, and Nb to a substrate, drying and pre-baking the substrate, and depositing a predetermined weight of LaNi x Nb y O 3-z The precursor can be prepared by forming it and then subjecting it to main calcination.

[0030] The metal salt may be a water-soluble salt such as a nitrate, oxynitrate, chloride, oxalate, tartrate, acetate, sulfate, etc. The metal salt may be an anhydrous salt or a hydrate salt. For La, Ni, and Nb, a water-dispersible sol of an oxide or hydroxide may be used instead of a metal salt. As the metal salt of Nb, it is preferable to use niobium oxalate or ammonium niobium oxalate from the viewpoint of solubility.

[0031] Adding organic ligands such as amino acids like glycine, or carboxylic acids like oxalic acid and tartaric acid to the coating solution can produce LaNi that exhibits low oxygen evolution overvoltage. x Nb y O 3-z This is preferable from the viewpoint of facilitating the preparation of the compound. In particular, when a coating solution in which glycine and a metal nitrate are dissolved is used, it becomes easy to prepare an electrode that exhibits a lower overpotential for oxygen evolution, and therefore glycine is a preferred organic ligand.

[0032] The concentration of an aqueous solution containing metal salts of La, Ni, and Nb is LaNi x Nb y O 3-z The standard molar concentration is preferably 0.3 mol / kg or more and 4 mol / kg or less. 2 Super 20μm 2 The sum of the areas of the following pores is 10 μm 2 More than 200μm 2It is easy to keep the concentration below 4 mol / kg of solvent. At 4 mol / kg or less, metal salts and organic ligands are easily dissolved, which is preferable from the viewpoint of productivity of the coating solution. More preferably, it is 0.35 mol / kg or more and 2.0 mol / kg or less of solvent, and even more preferably, it is 0.4 mol / kg or more and 1.0 mol / kg or less of solvent.

[0033] After the coating liquid is applied to the substrate, the drying temperature is preferably 50°C or higher and 200°C or lower. If the temperature is 50°C or higher, drying can be completed in 3 minutes to 1 hour, which is preferable from the viewpoint of productivity. If the temperature is 200°C or lower, the cooling time of the substrate after drying is shortened, which is preferable from the viewpoint of productivity.

[0034] The method of applying the coating liquid to the substrate is preferably a spray coating method. In particular, if the coating liquid atomized from a spray nozzle is dried appropriately to become highly viscous before landing on the substrate, the coating liquid film does not move on the substrate after landing, and a coating film with a uniform thickness can be formed on the substrate. By drying and baking this coating film with a uniform thickness, it becomes easy to prepare an electrode having a coefficient of variation of the inscribed circle diameter distribution of 0.2 to 0.6.

[0035] The temperature at which the dried substrate is pre-baked is preferably 300°C or higher and 500°C or lower. If the temperature is 300°C or higher, the pre-baking can be completed in 3 minutes to 1 hour, which is preferable from the viewpoint of productivity. If the temperature is 500°C or lower, the cooling time of the dried substrate can be shortened, which is preferable from the viewpoint of productivity.

[0036] Coating, drying, and pre-baking are performed to obtain the desired LaNi x Nb y O 3-z This process may be repeated to adjust the amount of electrode deposition. The deposition amount per one coating, drying, and pre-baking is 10 g / m 2 More than 15g / m 2 When the coefficient of variation of the inscribed circle diameter distribution is 0.2 or more and 0.6 or less, it is possible to produce an electrode with good productivity.

[0037] The temperature for the main firing can be from 500° C. to 1000° C., but firing at 650° C. or higher is preferred. Firing at 650° C. or higher is preferred from the viewpoint of productivity, since it makes it easy to prepare an electrode that exhibits a low oxygen evolution overvoltage in a firing time of from 10 minutes to 24 hours.

[0038] Nb may be added by a method in which a coating liquid containing a water-dispersible sol of a metal salt, or an oxide or hydroxide of La or Ni is applied in advance, dried, and pre-baked, and then a coating liquid containing a water-dispersible sol of a metal salt, or an oxide or hydroxide of Nb is applied to the electrode in a topcoat manner, dried, pre-baked, and then finally baked.

[0039] Alternatively, Nb may be added by first applying a coating liquid containing a water-dispersible sol of a metal salt, oxide, or hydroxide of La or Ni, followed by drying, pre-baking, and final baking, and then applying a coating liquid containing a water-dispersible sol of a metal salt, oxide, or hydroxide of Nb to the electrode in a topcoat manner, followed by drying, pre-baking, and final baking.

[0040] (electrolytic cell) FIG. 1 shows a side view of an example of an entire electrolytic cell including an electrolytic cell equipped with the electrode of this embodiment as an anode. FIG. 2 shows a cross section of the inside of an electrolytic cell in the part enclosed by the dashed square frame shown in FIG. 1 in an example of an electrolytic cell including an electrolytic cell equipped with the electrode of this embodiment as an anode. In the bipolar electrolytic cell 50 of this embodiment (see FIG. 3), the diaphragm 4 is in contact with the anode 2a and the cathode 2c to form a zero-gap structure Z (see FIG. 2). An outline of the electrolysis device used in the examples and comparative examples is shown in Figure 3. An outline of the bipolar electrolytic cell used in the electrolysis tests is shown in Figure 4.

[0041] (element) As shown in FIG. 1, in a bipolar electrolytic cell 50, a bipolar element 60 is disposed between an anode terminal element 51a and a cathode terminal element 51c, and diaphragms 4 are disposed between the anode terminal element 51a and the bipolar element 60, between adjacent bipolar elements 60, and between the bipolar element 60 and the cathode terminal element 51c.

[0042] In this embodiment, the portion between the partition walls 1 between two adjacent bipolar elements 60 and the portion between the partition walls 1 between an adjacent bipolar element 60 and a terminal element in the bipolar electrolytic cell 50 are particularly referred to as the electrolytic cell 65. The electrolytic cell 65 includes the partition wall 1, anode chamber 5a, anode 2a, and diaphragm 4 of one element, and the cathode 2c, cathode chamber 5c, and partition wall 1 of the other element.

[0043] (electrode chamber) 2, in the bipolar electrolytic cell 50 of this embodiment, electrode chambers 5 through which the electrolytic solution passes are defined by the partition wall 1, the outer frame 3, and the diaphragm 4. Here, the electrode chamber 5 on the anode side across the partition wall 1 is the anode chamber 5a, and the electrode chamber 5 on the cathode side is the cathode chamber 5c. In this embodiment, the header pipes of the bipolar electrolytic cell may be arranged in either an internal header type or an external header type, and the spaces occupied by the anode and cathode themselves may also be considered to be spaces inside the electrode chambers. In particular, when a gas-liquid separation box is provided, the space occupied by the gas-liquid separation box may also be considered to be spaces inside the electrode chambers.

[0044] (rib) In the bipolar electrolytic cell 65 for alkaline water electrolysis of this embodiment, the ribs 6 are preferably physically connected to the electrodes 2. With such a configuration, the ribs 6 serve as supports for the electrodes 2, making it easier to maintain the zero-gap structure Z. The ribs 6 are also preferably electrically connected to the partition wall 1. Furthermore, the provision of the ribs 6 can reduce convection that occurs in the electrode chambers 5 due to turbulence in the gas-liquid flow within the electrode chambers 5, thereby suppressing a local increase in the temperature of the electrolyte. Here, an electrode may be provided on the rib, or a current collector, a conductive elastic body, and an electrode may be provided on the rib in this order.

[0045] In the above-described example of a bipolar electrolytic cell for alkaline water electrolysis, a structure is adopted in the cathode chamber, in which the cathode rib-cathode current collector-conductive elastic body-cathode are stacked in this order, and a structure is adopted in the anode chamber, in which the anode rib-anode are stacked in this order. In the above-described example of the bipolar electrolytic cell for alkaline water electrolysis, the cathode chamber has the above-described "cathode rib-cathode current collector-conductive elastic body-cathode" structure, and the anode chamber has the above-described "anode rib-anode" structure; however, the present invention is not limited to this structure, and the anode chamber may also have an "anode rib-anode current collector-conductive elastic body-anode" structure. Specifically, in the bipolar electrolytic cell for alkaline water electrolysis of this embodiment, as shown in FIG. 2, ribs 6 (anode ribs, cathode ribs) are preferably attached to the partition wall 1. The ribs (anode ribs, cathode ribs) preferably have a role not only to support the anode or cathode but also to transmit current from the partition wall to the anode or cathode.

[0046] In the bipolar electrolytic cell for alkaline water electrolysis of this embodiment, it is preferable that at least a portion of the ribs be electrically conductive, and it is more preferable that the entire ribs be electrically conductive. With this configuration, an increase in cell voltage due to electrode deflection can be suppressed.

[0047] The ribs are generally made of a conductive metal, such as nickel-plated mild steel, stainless steel, or nickel. The ribs are preferably made of the same material as the partition walls, and nickel is most preferred.

[0048] The distance between adjacent anode ribs or the distance between adjacent cathode ribs is determined taking into consideration the electrolysis pressure and the pressure difference between the anode chamber and the cathode chamber.

[0049] If the spacing between anode ribs or between adjacent cathode ribs is too narrow, it not only hinders the flow of electrolyte and gas but also increases costs. A rib pitch of 10 mm or more allows gas to escape to the back surface of the electrode well. On the other hand, if the spacing is too wide, disadvantages arise, such as deformation of the electrodes (anode and cathode) held in place by a slight pressure difference between the anode chamber and the cathode chamber, and increased electrical resistance due to a reduced number of anode ribs and cathode ribs. A rib pitch of 150 mm or less makes the electrodes less likely to warp. The number of ribs, the length of the ribs, the angle between the ribs and the partition wall, the number of through holes, and the spacing (pitch) of the through holes in a given direction along the partition wall may be determined appropriately as long as the effects of the present invention are achieved. The ribs are preferably arranged parallel to a given direction along the partition wall (for example, the vertical direction, or, if the partition wall has a substantially rectangular shape in a plan view, the same direction as one of two pairs of opposing sides). The rib pitch of the anode ribs and the rib pitch of the cathode ribs may be the same or different, and it is preferable that the rib pitch of the anode ribs and the rib pitch of the cathode ribs both satisfy the above range.

[0050] The anode ribs and cathode ribs are attached to the partition wall by laser welding or the like.

[0051] The thickness of the rib may be 0.5 mm or more and 5 mm or less, taking into consideration cost, manufacturability, strength, etc., and a thickness of 1 mm or more and 2 mm or less is easily used, but is not particularly limited.

[0052] The electrodes and current collectors are usually attached to the ribs by spot welding, but other methods such as laser welding may also be used, or they may be tied together with a wire or string-like member for close contact. The ribs are fixed to the partition wall by means of spot welding, laser welding, or the like, in the same way as the anode or cathode.

[0053] (Hydrogen production method) Next, a method for producing hydrogen by alkaline water electrolysis using the bipolar electrolytic cell of this embodiment will be described.

[0054] In this embodiment, water electrolysis is performed by applying a current to a bipolar electrolytic cell equipped with an anode and a cathode as described above and through which an electrolyte is circulated, thereby producing hydrogen at the cathode. In this case, for example, a variable power supply can be used as the power source. A variable power supply is a power source derived from a renewable energy power plant whose output fluctuates every few seconds to minutes, unlike a power source that provides a stable output, such as grid power. The method of generating renewable energy is not particularly limited, but examples include solar power generation and wind power generation.

[0055] For example, in the case of electrolysis using a bipolar electrolytic cell, cationic electrolytes in the electrolyte migrate from the anode chamber of one element through the diaphragm to the cathode chamber of the adjacent element, and anionic electrolytes migrate from the cathode chamber of one element through the diaphragm to the anode chamber of the adjacent element. Therefore, current during electrolysis flows in the direction in which the elements are connected in series. That is, current flows from the anode chamber of one element to the cathode chamber of the adjacent element through the diaphragm. As a result of electrolysis, oxygen gas is produced in the anode chamber and hydrogen gas is produced in the cathode chamber.

[0056] The bipolar electrolytic cell 65 for alkaline water electrolysis of this embodiment can be used in a bipolar electrolytic cell 50, an electrolysis device 70 for alkaline water electrolysis, etc. Examples of the electrolysis device 70 for alkaline water electrolysis include a device including the bipolar electrolytic cell 50 of this embodiment, a liquid feed pump 71 for circulating the electrolytic solution, a gas-liquid separation tank 72 for separating the electrolytic solution from hydrogen and / or oxygen, and a water replenisher for replenishing water consumed by electrolysis.

[0057] The alkaline water electrolysis apparatus may further include a rectifier 74, an oxygen concentration meter 75, a hydrogen concentration meter 76, a flow meter 77, a pressure meter 78, a heat exchanger 79, a pressure control valve 80, and the like.

[0058] In the alkaline water electrolysis method using the alkaline water electrolysis apparatus, the current density applied to the electrolytic cell is 4 kA / m 2 ~20kA / m 2 Preferably, it is 6 kA / m2 ~15kA / m 2 It is more preferable that:

[0059] The electrodes, electrolytic cells, and hydrogen production methods according to the embodiments of the present invention have been described above with reference to the drawings. However, the electrodes, electrolytic cells, and hydrogen production methods according to the present invention are not limited to the above examples, and appropriate modifications can be made to the above embodiments. [Example]

[0060] Example 1 A 10 cm square nickel expand metal with a SW of 3.0 mm, LW of 4.5 mm, thickness of 1.2 mm, and an aperture ratio of 54% was prepared as the nickel porous substrate. This nickel expand metal was subjected to a blast treatment, then acid-treated in 6N hydrochloric acid at 50°C for 6 hours, washed with water, and dried to prepare a substrate for application. Next, solution A was prepared according to the composition of Example 1 in Table 1, and solution B in Table 2. Solution B was prepared by adding pure water to Nb2O5 sol with a primary particle size of 5 nm or less, and the Nb concentration was confirmed by ICP-AES (inductively coupled plasma atomic emission spectroscopy). Using a spray coating device (rCoater sold by Asahi Sunac Corporation), Liquid A was applied to both sides of the substrate, which was then dried at 60°C for 10 minutes and then baked at 400°C for 10 minutes to form a metal oxide layer on the surface of the substrate. After repeating the cycle of applying, drying, and baking liquid A five times, liquid B was applied to both sides of the substrate using a spray coater and then dried at 60°C for 10 minutes. The weight increase compared to the substrate before application was calculated to be 81 mg. The substrate was then baked at 400°C for 10 minutes to form a metal oxide layer on the surface of the substrate. This cycle of applying, drying, and baking liquid A five times and liquid B once was repeated five times, for a total of 25 applications of liquid A and 5 applications of liquid B. Furthermore, it was baked at 650°C for 1 hour, and the adhesion amount was 391g / m 2 A metal oxide layer of the above was formed to obtain the electrode of Example 1. The amount of metal oxide layer attached to the substrate was 3.91 g, and LaNi 0.8 O 2.7The weight of 1 mole of LaNi is 229.0 g, and the weight of 1 mole of Nb2O5 is 265.8 g. Therefore, by applying 405 mg of Nb2O5, 0.8 O 2.71 The composition was LaNi 0.8 Nb 0.2 O 3.2 It was found that an electrode of this order was obtained.

[0061] Example 2 A substrate for application was prepared in the same manner as in Example 1. Next, liquids A and B of Example 2 in Tables 1 and 2 were prepared. In the same manner as in Example 1, Liquid A was applied to both sides of the substrate, which was then dried at 60°C for 10 minutes and then baked at 400°C for 10 minutes to form a metal oxide layer on the surface of the substrate. This cycle of applying, drying, and baking with Liquid A was repeated five times, and then Liquid B was applied to both sides of the substrate in the same manner as in Example 1, followed by drying at 60°C for 10 minutes. The weight increase relative to the substrate before application was calculated to be 60 mg. The substrate was then baked at 400°C for 10 minutes to form a metal oxide layer on the surface of the substrate. This cycle of applying, drying, and baking liquid A five times and liquid B once was repeated five times, for a total of 25 applications of liquid A and 5 applications of liquid B. Furthermore, it is baked at 650℃ for 1 hour, and the adhesion amount is 380g / m 2 A metal oxide layer of the above was formed to obtain the electrode of Example 2. The amount of metal oxide layer attached to the substrate was 3.80 g, and LaNi 0.85 O 2.775 The weight of 1 mole of LaNi is 233.1g, and the weight of 1 mole of Nb2O5 is 265.8g. Therefore, by applying 300mg of Nb2O5, 0.85 O 2.7751 The composition was LaNi 0.85 Nb 0.15 O 3.15 It was found that an electrode of this order was obtained.

[0062] Example 3 A substrate for application was prepared in the same manner as in Example 1. Next, liquids A and B of Example 3 in Tables 1 and 2 were prepared. In the same manner as in Example 1, Liquid A was applied to both sides of the substrate, which was then dried at 60°C for 10 minutes and then baked at 400°C for 10 minutes to form a metal oxide layer on the surface of the substrate. This cycle of applying, drying, and baking liquid A was repeated 30 times, after which liquid B was applied to both sides of the substrate and dried at 60°C for 10 minutes. The weight increase compared to the substrate before application was calculated to be 11.6 mg. The substrate was then baked at 400°C for 10 minutes to form a metal oxide layer on the surface of the substrate. Furthermore, it was baked at 700°C for 1 hour, and the adhesion amount was 401g / m 2 A metal oxide layer of the above was formed to obtain the electrode of Example 3. The amount of metal oxide layer attached to the substrate was 4.01 g, and LaNi 0.795 O 2.6925 The weight of 1 mole of LaNi is 233.1g, and the weight of 1 mole of Nb2O5 is 265.8g. Therefore, by applying 11.6mg of Nb2O5, 0.795 O 2.6925 The composition was LaNi 0.795 Nb 0.005 O 2.705 It was found that an electrode of this order was obtained.

[0063] Example 4 A substrate for application was prepared in the same manner as in Example 1. Next, solutions A and B of Example 4 in Tables 1 and 2 were prepared. In the same manner as in Example 1, Liquid A was applied to both sides of the substrate, which was then dried at 60°C for 10 minutes and then baked at 400°C for 10 minutes to form a metal oxide layer on the surface of the substrate. This cycle of applying, drying, and baking liquid A was repeated 35 times, after which liquid B was applied to both sides of the substrate and dried at 60°C for 10 minutes. The weight increase compared to the substrate before application was calculated to be 27 mg. The substrate was then baked at 400°C for 10 minutes to form a metal oxide layer on the surface of the substrate. Furthermore, it was baked at 800°C for 1 hour, and the adhesion amount was 503g / m 2 A metal oxide layer of the above was formed to obtain the electrode of Example 4. The amount of metal oxide layer attached to the substrate was 5.03 g, the weight of 1 mole of LaNiO3 was 245.5 g, and the weight of 1 mole of Nb2O5 was 265.8 g. Therefore, by applying 27 mg of Nb2O5, the ratio of Nb to LaNiO3 was 1 mole and 0.01 mole was applied, resulting in a composition of LaNiNb 0.01 O 3.025 It was found that an electrode of this order was obtained.

[0064] Example 5 A substrate for application was prepared in the same manner as in Example 1. Next, liquids A and B of Example 5 in Tables 1 and 2 were prepared. In the same manner as in Example 1, Liquid A was applied to both sides of the substrate, which was then dried at 60°C for 10 minutes and then baked at 400°C for 10 minutes to form a metal oxide layer on the surface of the substrate. This cycle of applying, drying, and baking liquid A was repeated 35 times, after which liquid B was applied to both sides of the substrate and dried at 60°C for 10 minutes. The weight increase compared to the substrate before application was calculated to be 67.7 mg. The substrate was then baked at 400°C for 10 minutes to form a metal oxide layer on the surface of the substrate. This cycle of applying, drying, and baking liquid B was repeated once more. Furthermore, it was baked at 750°C for 1 hour, and the adhesion amount was 513g / m 2 A metal oxide layer of the above was formed to obtain the electrode of Example 5. The amount of metal oxide layer attached to the substrate was 5.13 g, the weight of 1 mole of LaNiO3 was 245.5 g, and the weight of 1 mole of Nb2O5 was 265.8 g. Therefore, by applying 135 mg of Nb2O5, the ratio of Nb to LaNiO3 was 0.05 moles, and the composition was LaNiNb 0.05 O 3.125 It was found that an electrode of this order was obtained.

[0065] Example 6 A substrate for application was prepared in the same manner as in Example 1. Next, liquids A and B of Example 6 in Tables 1 and 2 were prepared. In the same manner as in Example 1, Liquid A was applied to both sides of the substrate, which was then dried at 60°C for 10 minutes and then baked at 400°C for 10 minutes to form a metal oxide layer on the surface of the substrate. This cycle of applying, drying, and baking liquid A was repeated seven times, after which liquid B was applied to both sides of the substrate and dried at 60°C for 10 minutes. The weight increase compared to the substrate before application was calculated to be 52 mg. The substrate was then baked at 400°C for 10 minutes to form a metal oxide layer on the surface of the substrate. This cycle of applying, drying, and baking liquid A seven times and liquid B once was repeated five times, for a total of 35 applications of liquid A and five applications of liquid B. Furthermore, it was baked at 700°C for 1 hour, and the adhesion amount was 526g / m 2 A metal oxide layer of the above was formed to obtain the electrode of Example 6. The amount of metal oxide layer attached to the substrate was 5.26 g, and LaNi 1.1 O 3.15 The weight of 1 mole of LaNi is 253.8g, and the weight of 1 mole of Nb2O5 is 265.8g. Therefore, by applying 260mg of Nb2O5, 1.1 O 3.15 The composition was LaNi 1.1 Nb 0.1 O 3.4 It was found that an electrode of this order was obtained.

[0066] Example 7 A substrate for application was prepared in the same manner as in Example 1. Next, liquids A and B of Example 7 in Tables 1 and 2 were prepared. In the same manner as in Example 1, Liquid A was applied to both sides of the substrate, which was then dried at 60°C for 10 minutes and then baked at 400°C for 10 minutes to form a metal oxide layer on the surface of the substrate. This cycle of applying, drying, and baking liquid A was repeated 20 times, after which liquid B was applied to both sides of the substrate and dried at 60°C for 10 minutes. The weight increase compared to the substrate before application was calculated to be 7.8 mg. The substrate was then baked at 400°C for 10 minutes to form a metal oxide layer on the surface of the substrate. Furthermore, it was baked at 650°C for 1 hour, and the adhesion amount was 267g / m 2 A metal oxide layer of the above was formed to obtain the electrode of Example 3. The amount of metal oxide layer attached to the substrate was 2.67 g, and LaNi 0.795 O 2.6925The weight of 1 mole of LaNi is 2.67g, and the weight of 1 mole of Nb2O5 is 265.8g. Therefore, by applying 7.8mg of Nb2O5, 0.795 O 2.6925 The composition was LaNi 0.795 Nb 0.005 O 2.705 It was found that an electrode of this order was obtained.

[0067] (Comparative Example 1) A nickel expand metal with a SW of 3.0 mm, a LW of 4.5 mm, a thickness of 1.2 mm, and an aperture ratio of 54% was prepared as the nickel porous substrate. After blasting this nickel expand metal, it was acid-treated in 6N hydrochloric acid at 50°C for 6 hours, washed with water, and dried to prepare a substrate for application. Next, a coating solution was prepared by mixing lanthanum acetate 1.5 hydrate and nickel nitrate hexahydrate to concentrations of 0.20 mol / L and 0.20 mol / L, respectively. A tray containing the coating solution was placed at the bottom of the coating roll, and the coating solution was soaked into an EPDM coating roll. A roll was placed above it so that the roll and the coating solution were always in contact with each other, and a PVC roller was placed on top of that to apply the coating solution to the substrate (roll method). The substrate was quickly passed between two EPDM sponge rolls before the coating solution dried. After drying at 50°C for 10 minutes, the substrate was baked in a muffle furnace at 400°C for 10 minutes to form a metal oxide layer on the surface. This cycle of roll coating, drying and baking was repeated 75 times, and then the coating was further baked at 600°C for 1 hour, resulting in a coating weight of 303 g / m 2 A metal oxide layer of the above was formed on the surface of the cathode to obtain an anode for water electrolysis.

[0068] (Comparative Example 2) A substrate for application was prepared in the same manner as in Comparative Example 1. Next, coating solutions were prepared so that the concentrations of lanthanum nitrate hexahydrate, nickel nitrate hexahydrate, ammonium niobium oxalate n-hydrate, and glycine were 0.20 mol / L, 0.16 mol / L, 0.04 mol / L, and 0.36 mol / L, respectively. As in Comparative Example 1, the cycle of roll coating, drying and firing was repeated 40 times by the roll method, and then firing was carried out at 700°C for 1 hour to form a metal oxide layer, with a deposition weight of 145 g / m 2 A water electrolysis anode was obtained.

[0069] (Calculation method for the coefficient of variation of the inscribed circle diameter distribution of the cross section of the catalyst layer, the maximum inscribed circle diameter, and the proportion of inscribed circle diameters of 100 μm or less) A small piece of the electrode was embedded in epoxy resin, and then a cut surface was prepared. The cut surface was then processed using a broad-beam argon ion beam processing device (Hitachi High-Technologies Corporation, "E3500") at an acceleration voltage of 6 kV. The cut surface of the electrode to be observed was parallel to the expanded metal strand and passed through the center of the strand. The cross section was observed under an electron microscope (Hitachi High-Technologies Corporation, "S4800") at an accelerating voltage of 5 kV and a magnification of 50x. The cross section image taken using a YAG detector was saved as a BMP file with a data size of 1280 x 960 pixels. The size of one pixel was 198.4375 nm. Using the image processing software "ImageJ," regions consisting only of the embedding resin and electrode cross-section were extracted from the cross-sectional photographs according to the following steps 1) to 15). The coefficient of variation of the inscribed circle diameter distribution, the maximum inscribed circle diameter, and the proportion of inscribed circle diameters of 100 μm or less were measured for each region. Ten regions consisting of the embedding resin and electrode were extracted from the cross-sectional photographs, with no overlapping between them. The average values ​​of the coefficient of variation of the inscribed circle diameter distribution, the maximum inscribed circle diameter, and the proportion of inscribed circle diameters of 100 μm or less were calculated for each of the 10 regions. These were used as the measurement results for the coefficient of variation of the inscribed circle diameter distribution, the maximum inscribed circle diameter, and the proportion of inscribed circle diameters of 100 μm or less for the examples and comparative examples. The measurement results for Examples 1 to 7 and Comparative Examples 1 and 2 are shown in Table 3. 1) Open the BMP file of the cross-sectional image and select 8-bit in the Type submenu of the Image menu. Figure 5 shows an example of a cross-sectional image. 2) In the Set scale submenu of the Analyze menu, set Distance in Pixels: 1, Known distance: 1.984375, Pixel aspect ratio: 1.0, Unit of length: μm, and click OK. 3) In the Selection submenu of the Edit menu, select the Specify command, check the Scaled units (μm) checkbox, set Width: 2540, X coordinate: 0, and set the Height and Y coordinate values ​​appropriately to specify an area in which only the electrode cross section and embedding resin are selected, then click OK. Set the area so that the electrode is connected from the right edge to the left edge and is never hidden by the top, bottom, left, or right edges of the set area. 4) Execute the Crop command in the Image menu to cut out the area consisting of only the electrode cross section and the embedding resin for image processing. Figure 6 shows an example of the cut-out area from Figure 5. 5) Name and save the cropped area. 6) In the Filters submenu of the Process menu, select Median..., set Radius:4, and click OK to perform the filtering process. 7) Select the Multi Otsu Threshold plugin from the Plugins menu, set numLevels to 3, and click OK. 8) Select Region 1, select the Threshold command in the Adjust submenu of the Image menu, select Otsu as the automatic threshold setting method, select B&W as the display method, check the Dark background checkbox, click the Auto button, click the Apply button, and perform binarized extraction of the catalyst layer. Figure 7 shows an example of an image in which the catalyst layer has been binarized and extracted from Figure 6. 9) Select the Dilate command from the Binary submenu of the Process menu and execute it 20 times. 10) Select the Erode command from the Binary submenu of the Process menu and execute it 20 times. Figure 8 shows an example of a processed image. 11) From the Plugins menu, select the BoneJ plugin, then select the Thickness command. Check the Thickness checkbox, the Graphic Results checkbox, and the Mask thickness map checkbox, then click OK. 12) Divide Tb.Th Std Dev (μm) in the Results window by Tb.Th Mean (μm) to obtain the coefficient of variation of the inscribed circle diameter distribution. Tb.Th Max (μm) is the maximum inscribed circle diameter. 13) Select the Graphic Results window, filename_Tb.Th(G) (the filename is the one set in step 5), select the Histogram command from the Analyze menu, check the Bins: 256 and Use pixel value range checkboxes, and click OK. Figure 9 shows an example of a graphic in the filename_Tb.Th(G) window. 14) Click the List button in the Histogram of filename_Tb window to display a window with 256 rows and 3 columns of histogram data, with the columns labeled "index," "bin start," and "count." 15) The percentage (%) of inscribed circle diameters of 100 μm or less is calculated from the histogram data using the following formula. Percentage of inscribed circle diameters of 100 μm or less (%) = ((sum of count column values ​​for rows where bin start is 0 to 100) - (count column value for rows where bin start is 0)) / (sum of count column) * 100

[0070] (Ultrasonic Erosion Test Method) Using an ultrasonic erosion tester GSD600AT manufactured by Sonic Technology Co., Ltd., the electrodes were fixed so that the distance between the 2 cm square electrode and transducer was 2.5 mm in pure water at 20°C, and ultrasonic waves were irradiated for 3 minutes under the conditions of an output of 350 W, a load level of 5, and an amplitude of 40 μm.

[0071] (Method for measuring oxygen overvoltage of an electrode) The oxygen overvoltage of the electrode was measured by the following procedure. The test electrode was cut to a size of 2 cm x 2 cm and fixed to a PTFE-coated nickel rod with a nickel screw. A platinum mesh was used as the counter electrode, and the current density was 6 kA / m in a 32 wt% sodium hydroxide aqueous solution at 80°C. 2 The electrolyte was electrolyzed with 1000 kJ / cm² and the oxygen overvoltage was measured. The oxygen overvoltage was measured using a three-electrode method using a Luggin capillary to eliminate the effects of ohmic loss due to solution resistance. The distance between the tip of the Luggin capillary and the anode was always fixed at 1 mm. A Solartron potentiogalvanostat "1470E System" was used to measure the oxygen overvoltage. A silver-silver chloride (Ag / AgCl) electrode was used as the reference electrode for the three-electrode method. The electrolyte resistance that could not be completely eliminated using the three-electrode method was measured using the AC impedance method, and the oxygen overvoltage was corrected based on the measured electrolyte resistance. A Solartron "1255B" frequency response analyzer was used to obtain a Cole-Cole plot, plotting the real and imaginary parts, and then analyzed using equivalent circuit fitting to calculate the electrolyte resistance and double layer capacitance. The ohmic loss that could not be completely eliminated by the three-electrode method was measured by the AC impedance method, and the oxygen overvoltage was corrected based on the measured ohmic loss. The ohmic loss was measured using a frequency response analyzer "1255B" manufactured by Solartron. Table 3 shows the evaluation results for Examples 1 to 7 and Comparative Examples 1 and 2.

[0072] Example 8 An electrolytic cell for alkaline water electrolysis and a bipolar electrolytic cell were prepared as follows. -anode- It was prepared in the same manner as in Example 4. -cathode- The conductive substrate used was a plain-woven mesh substrate made of nickel thin wires with a diameter of 0.15 mm woven at 40 meshes, on which platinum was supported. -Partition walls, outer frames- The bipolar element used had a partition wall separating the anode and cathode and an outer frame surrounding the partition wall. All of the materials used for the partition wall and the bipolar element frame, which come into contact with the electrolyte, were nickel. -Conductive elastic body- The conductive elastic body used was made by weaving nickel wire with a wire diameter of 0.15 mm and corrugating it to a wave height of 5 mm. -diaphragm- A coating solution having the following component composition was obtained using zirconium oxide (trade name "EP Zirconium Oxide", manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.), N-methyl-2-pyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.), polysulfone ("Udel" (registered trademark), manufactured by Solvay Advanced Polymers), and polyvinylpyrrolidone (weight average molecular weight (Mw) 900,000, manufactured by Wako Pure Chemical Industries, Ltd.). Polysulfone: 15 parts by mass Polyvinylpyrrolidone: 6 parts by mass N-methyl-2-pyrrolidone: 70 parts by mass Zirconium oxide: 45 parts by mass The coating solution was applied to both surfaces of a polyphenylene sulfide mesh (manufactured by Kureha Co., Ltd., film thickness 280 μm, mesh size 358 μm, fiber diameter 150 μm) as a substrate. Immediately after coating, the substrate coated with the coating solution was exposed to steam and then immersed in a coagulation bath to form a coating film on the substrate surface. The coating film was then thoroughly washed with pure water to obtain a porous film. -gasket- The gasket used was a square gasket with a thickness of 4.0 mm, a width of 18 mm, and an inner dimension of 504 mm square. It had an opening on the inside with the same dimensions as the electrode chamber in a plan view, and a slit structure for inserting and holding the diaphragm. -Zero-gap type multi-pole element- The external header type zero gap cell unit 60 is a rectangle measuring 540 mm x 620 mm, and the area of ​​the current-carrying surfaces of the anode 2a and cathode 2c is 500 mm x 500 mm. The cathode side of the zero gap bipolar element 60 is composed of a laminate of the cathode 2c, conductive elastic body 2e, and cathode current collector 2r, connected to the partition wall 1 via the cathode rib 6, and has a cathode chamber 5c through which the electrolyte flows. On the anode side, the anode 2a is connected to the partition wall 1 via the anode rib 6, and has an anode chamber 5a through which the electrolyte flows (Figure 2). The depth of the anode chamber 5a (anode chamber depth, the distance between the partition wall and the anode in FIG. 2) was 25 mm, and the depth of the cathode chamber 5c (cathode chamber depth, the distance between the partition wall and the cathode current collector in FIG. 2) was 25 mm, and they were made of nickel. The thickness of the nickel partition wall 1 to which the nickel anode rib 6 with a height of 25 mm and a thickness of 1.5 mm and the nickel cathode rib 6 with a height of 25 mm and a thickness of 1.5 mm were attached by welding was 2 mm. The cathode current collector 2r was a nickel expand substrate that had been pre-blasted. The substrate was 1 mm thick and had an aperture ratio of 54%. The conductive elastic body 2e was fixed onto the cathode current collector 2r by spot welding. By stacking this zero-gap bipolar element with a gasket that holds the diaphragm, a zero-gap structure Z was formed in which the anode 2a and cathode 2c were pressed against the diaphragm 4.

[0073] Using the electrolysis apparatus of Example 8, the electrolysis was carried out at an electrolyte temperature of 80°C and a current density of 6 kA / m 2 Water electrolysis was performed by continuously applying a positive current for 100 hours so that the voltage across each cell of Example 8 was measured. The voltage across each cell was monitored and recorded over time. The average cell voltage of each cell for the three cells of Example 8 was calculated and compared. In Example 8, the average overvoltage of the three cells after 100 hours of current application was a low value of 1.73 V. Therefore, it can be concluded that the anode of Example 4 was less affected by wear even during long-term operation, and was able to achieve a low cell voltage.

[0074] [Table 1]

[0075] [Table 2]

[0076] [Table 3] [Industrial Applicability]

[0077] The electrode of the present invention has a low overvoltage for oxygen generation and is highly resistant to wear, and therefore can be suitably used as an anode in a water electrolysis cell for electrolyzing water containing alkali. [Explanation of symbols]

[0078] 1 Bulkhead 2 electrodes 2a anode 2c cathode 2e Conductive elastic body 2r Cathode current collector 3 Outer frame 4 Diaphragm 5a Anode chamber 5c cathode chamber 6. Ribs 7 Gasket 50 bipolar electrolyzer 51g fast head, loose head 51i Insulating plate 51a Anode terminal element 51c Cathode Terminal Element 51r tie rod 60 Multi-pole element 65 Electrolysis Cell 70 Electrolyzer 71 Liquid transfer pump 72 Gas-liquid separation tank 74 Rectifier 75 Oxygen concentration meter 76 Hydrogen concentration meter 77 Flow meter 78 Pressure Gauge 79 Heat exchanger 80 Pressure control valve Z Zero gap structure

Claims

1. On the substrate, LaNi ｘ M ｙ O ３－ｚ (x+y is 0.8 or more and 1.2 or less, y is 0.005 or more and 0.2 or less, z is -0.5 or more and 0.5 or less, and M contains at least one of Nb, Ta, Sb, Ti, Mn, and Zr), ｘ M ｙ O ３－ｚ An electrode characterized in that, in a layer cross section, the coefficient of variation of the inscribed circle diameter distribution is 0.2 to 0.6, the maximum value of the inscribed circle diameter is 132 μm to 400 μm, and the deposition amount of the LaNi x M y O 3-z is 267 g / m 2 to 526 g / m 2 .

2. 2. The electrode according to claim 1, wherein the proportion of inscribed circle diameters of 100 μm or less is 40% or less in the distribution of inscribed circle diameters.

3. 3. An electrolytic cell comprising the electrode according to claim 1 or 2 as an anode.

4. In a method for producing hydrogen by electrolyzing alkali-containing water in an electrolytic cell, the electrolytic cell is provided with at least an anode and a cathode, and the anode is provided with a LaNi substrate. ｘ M ｙ O ３－ｚ (x+y is 0.8 or more and 1.2 or less, y is 0.005 or more and 0.2 or less, z is -0.5 or more and 0.5 or less, and M contains at least one of Nb, Ta, Sb, Ti, Mn, and Zr), ｘ M ｙ O ３－ｚ A method for producing hydrogen, characterized in that, in a layer cross section, the coefficient of variation of the inscribed circle diameter distribution is 0.2 to 0.6, the maximum value of the inscribed circle diameter is 132 μm to 400 μm, and the deposition amount of the LaNi x M y O 3-z is 267 g / m 2 to 526 g / m 2 .

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