KR820000885B1 - Process for preparing electrode - Google Patents

Abstract

This electrode is coated with an alloy of >= 1 of Cr, Mn, Ta, Nb, Si, Zr, Ge, etc and lanthanides 20-95 with >= 1 of Ni, W, Ag, Co and Mo 5-80%, etched to remove the 1st group metals partially or entirely from the surface layer to a 0.01-50μ depth giving an elec. double layer capacitance >= 5000 μF/cm2. This electrode is used as a cathode in brine electrolysis. The NaOH is obtained is more concd. Than with an Fe cathode. When satd. NaCl at pH 3.3 and 57% NaOH were electrolyzed with this cathode, a Ti anode coated with RuO2, and Nafion 120 diaphragm at 90≰and c.d. 20 A/dm2, the H overvoltage was 0.06v vs. SCE. vs. 0.36 with the original electrode.

Description

Preparation of the electrode

1 is a partial cross-sectional view of an example of an electrode according to the present invention.

2 is a partial cross-sectional view of a surface of another example of an electrode according to the present invention.

3 is a diagram illustrating the configuration of an electrolytic cell used in one embodiment of the present invention.

4 is an explanatory view of the configuration of a plating apparatus used in an embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for producing an electrode with a low overvoltage used in electrolytic solution, in particular, a method for producing a cathode with a low hydrogen overvoltage.

For example, when electrolytic products are obtained by electrolyzing an aqueous solution such as electrolytic solution of alkaline chloride to produce caustic alkali and chlorine, various corrosion resistant electrodes are used. Such an electrode can reduce the power ratio by making the overvoltage generated when electrolyzing an aqueous liquid such as an alkaline chloride aqueous solution as low as possible, and thereby obtain an electrolytic product at low cost.

Therefore, with respect to the positive electrode, various studies have been conducted on the material and the processing method thereof for the purpose of reducing the chlorine overvoltage of the positive electrode, and some have already been put into practical use. Since the diaphragm method which electrolytically publishes a diaphragm with respect to a cathode is developed, the electrode which has low hydrogen overvoltage and alkali resistance is calculated | required. In electrolytic alkali chloride solution using the asbestos diaphragm currently performed, iron is used as a cathode.

Then, in order to further reduce the hydrogen overvoltage, sand blasting treatment (for example, "Surface Treatment Handbook", published by Japan Industrial Bureau Industrial Book, publication 541-542 on the surface treatment handbook) is performed. A method is also proposed. However, such asbestos diaphragm method has a disadvantage in that the caustic soda concentration obtained is about 10 to 13% by weight, and salts are mixed as impurities in the caustic soda aqueous solution. The method of electrolyzing aqueous solution is developed and is industrializing.

According to this method, a high concentration of caustic soda of 25 to 40% by weight can be obtained without mixing salts as impurities. In this case, if the conventional iron is used as the cathode, the caustic soda concentration is high and the electrolysis temperature is 80 to 120 ° C., so that the iron cathode causes stress corrosion cracking or part of the iron is eluted in the catholyte. This can lead to impaired purity.

An object of the present invention is to obtain an electrode having a better corrosion resistance to caustic alkali than iron to effectively reduce hydrogen overvoltage and furthermore, the effect of which can be maintained for a long time.

That is, the present invention provides an electrode in which a nickel plated layer in which a portion of nickel-containing particles is exposed on its surface is formed on an electrode core.

According to the present invention, a large number of particles of the present invention are attached to the electrode surface, and the surface of the electrode is microporous when viewed macroscopically.

As described above, the electrode of the present invention has a large number of particles containing nickel having a low hydrogen overvoltage on the surface of the electrode, so that the electrode surface becomes microporous, as described above. This can effectively reduce the hydrogen overvoltage.

Furthermore, since the particles of the present invention are firmly adhered to the electrode surface by the metal layer, they are difficult to deteriorate and can significantly prolong the sustainability of the low hydrogen overvoltage.

The electrode core of the present invention is selected from any suitable conductive metal, such as Ti, Zr, Fe, Ni, V, Mo, Cu, Ag, Mn, a metal selected from platinum group metal, graphite, Cr, or a metal thereof as the material thereof. Alloy can be adopted. Among these, it is preferable to employ Fe, Fe alloys (Fe-Ni alloys, Fe-Cr alloys, etc.), Ni, Ni alloys (Ni-Cu alloys, Ni-Cr alloys, etc.), Cu, Cu alloys, and the like.

In particular, preferred electrode cores are Fe, Cu, Ni, Fe-Ni alloy, Fe-Ni-Cr alloy.

The structure of the electrode core can be any suitable shape and dimensions according to the structure of the electrode to be used. As the shape, for example, plate shape, porous shape, reticular shape (for example, expanded metal, etc.), foot shape (par- allel screen shape), and these may be flat, curved or normal.

The exposed particles of nickel can be made from the metal itself, which is based on nickel.

In the case where the metal is mainly used, as a component other than the metal, a metal, such as Al, Zn, Mg, Sn, etc., which is related to its content but does not adversely affect the reduction of hydrogen overvoltage, may be employed. Can be. Although the average particle diameter of particle | grains is related also to the porosity of the electrode surface and the dispersibility of the particle | grains at the time of electrode manufacture mentioned later, 0.1 micrometer-100 micrometers are enough.

It is preferably from 0.9 μm to 50 μm, more preferably from 1 μm to 30 μm in view of porosity and the like on the electrode surface within the above range.

In addition, the particles of the present invention are preferably surface porous in order to give a lower hydrogen overvoltage to the electrode.

Here, the surface porosity does not mean that the entire surface of the particles is porous, and it is sufficient that only the exposed portion of the plating layer of the above-described metal is porous.

Although the degree of porosity is considerably greater, the porosity is preferably 20 to 90% because the mechanical strength of the particles is reduced when the porosity is excessively large. More preferably, the range is 35 to 85%, particularly preferably 50 to 80%.

The porosity is a value measured by a known mercury porosimetry or mercury substitution method.

Various methods can be employed to make the porous material. For example, a method of removing Ni and metals from the Ni-based alloy to make it porous, in addition, carbonylation of Ni and thermal decomposition of the Ni A method of obtaining a metal, a method of obtaining a porous metal by pyrolyzing an organic acid salt of Ni, a method of obtaining a porous metal by heating an oxide of Ni in a hydrogen reducing atmosphere, and the like can be employed. Among them, in view of workability, a method of removing metals other than Ni from an alloy mainly containing Ni is preferable. In this case, a method of removing at least a part of the second metal by caustic alkali treatment using Ni as the first metal and an alloy with a second metal selected from Al, Zn, Mg, and Sn is employed. Particularly preferred. As such an alloy, a Ni-Al alloy, a Ni-Zn alloy, a Ni-Mg alloy, or a Ni-Sn alloy can be employed, and among them, a Ni-Al alloy is preferable. Such a preferred alloy is specifically unleached Raney Nickel.

In the present invention, as the metal to be used as the layer for attaching the particles of the present invention, a metal having alkali resistance and capable of firmly attaching the particles should be employed.

Therefore, Ni metal is employed. In particular, it is preferable to employ | adopt the metal of the same kind as the metal used as the main body of the particle | grains employ | adopted.

Although the thickness of the layer of this invention changes also with the particle diameter of the particle | grains employ | adopted, 20-200 micrometers is enough, More preferably, it is 25-150 micrometers, Especially preferably, it is 30-100 micrometers. This is because in the present invention, a part of the above-mentioned particles are adhered in a state of being embedded in a plating layer made of metal on the electrode core. In order to understand such a state, sectional drawing of the electrode surface of this invention is shown in FIG. As shown here, a plating layer 2 made of metal is provided on the electrode core 1, and the layer 2 contains a portion of the particles 3 exposed to the surface of the layer. At this time, the proportion of the particles in the layer (2) is preferably 5 to 80% by weight, more preferably 10 to 50% by weight. In addition to such a state, by providing an intermediate layer made of Ni metal between the electrode core and the plating layer containing the particles of the present invention, durability of the electrode according to the present invention can be improved. The intermediate layer may be the same or different from the metal of the layer. However, the intermediate layer and the metal of the plating layer are preferably the same in terms of adhesion to the above-described plating layer. The thickness of the intermediate layer is preferably 5 to 100 mu in terms of mechanical strength, more preferably 20 to 80 mu and particularly preferably 30 to 50 mu.

In order to understand the electrode which provided such an intermediate | middle layer, sectional drawing of an electrode is shown in FIG.

(1) is an electrode core, (4) is an intermediate | middle layer, (2) is a layer containing particle | grains, (3) is particle | grains.

As evident in FIGS. 1 and 2, the electrode of the present invention appears to be exposed to a large number of particles on the surface of the electrode when viewed microscopically. The surface of the electrode is porous.

As described above, since the degree of porosity is also related to the charge of hydrogen overvoltage, the degree of porosity can be sufficiently achieved if the degree of porosity is 1000 μF / cm ² or more in terms of electric double layer capacity. Preferably in the said range, it is 2000 micro F / cm <^2> or more, and patent preferably 5000 micro F / cm <^2> or more. The electric double layer capacity is the capacitance of the electric double layer formed by relatively distributing positive and negative ions at a short distance near the electrode surface when the electrode is immersed in the electrolyte solution. Indicates.

This capacitance becomes larger as the electrode surface becomes larger. Therefore, as the electrode surface becomes porous and the electrode surface area becomes larger, the electric double capacitance of the electrode surface also becomes larger. Therefore, it is possible to know the electrochemically effective electrode surface, that is, the porosity of the electrode surface according to the electric double layer capacity.

In addition, since the electric double layer capacity also changes according to the temperature at the time of measurement or the kind, concentration, electrode potential, etc. of an electrolyte solution, the electric double layer capacity of this invention means the value measured by the following method.

The test piece (electrode) was immersed in 40 wt% NaOH aqueous solution (25 ° C.), and a platinum black part platinum plate having an apparent area approximately 100 times larger than that of the test piece was inserted into the counter electrode and the cell impedance in this state was Koolau. Measured with a kohlar-ausch bridge to determine the electrical double layer capacity of the specimen.

As a specific means for attaching the electrode surface layer, various methods, for example, a dispersion plating method, a melt spraying method, or the like can be employed, and among these, the dispersion plating method is particularly preferable because the particles of the present invention can be adhered well.

In the dispersion plating method, plating is performed using an electrode core as a cathode in an aqueous solution containing a metal forming a metal layer, ie, a bath in which particles composed mainly of nickel are dispersed.共 析) is to. In order to maintain such a dispersed state, various methods can be employed. For example, a mechanical stirring, an air stirring, a liquid circulation method, ultrasonic stirring, a fluidized bed, or the like can be adopted. However, it has been reported that when the plating is carried out using conductive particles as in the present invention, the shape of the electrodeposition becomes dendritic and the strength is weak (R. Bazzard, Trans. Just.Metal Finishing, '72, 50, 63 J. Foster et al, ibid, '76, 54 178).

Therefore, as a result of a detailed examination of the dispersion plating method, when the stirring is weak, the electrodeposited material becomes dendritic and the strength is weak. However, when the stirring is performed strongly, the shape of the electrodeposited product becomes extremely dendritic and sufficient strength is obtained. It has been found that the overvoltage is low enough. In addition, it was found that excessive agitation reduces the amount of vacancies in the particles and smoothed the shape of the electrodeposited material, resulting in high strength but high hydrogen overvoltage.

In other words, it has been found that the hydrogen overvoltage, strength and shape of the electrodeposition of the dispersion plating are closely related to the dispersion state.

Therefore, in the case of producing a practical industrial size electrode, if the vacancies are partially uneven, the current is concentrated in a place where a large amount of vacancies is low, and the current is concentrated in a place where the amount of vacancies is small, so that the current is difficult to flow, and the current line distribution is largely disturbed. It is unfavorable because of the result.

Therefore, uniform vacancy, that is, dispersion plating in a uniform stirring state is essential. Therefore, as a result of various examinations of the uniform formula method, it was found that a method of dispersing and plating particles by moving the porous plate up and down in the lower part of the plating tank was good. In addition, it has been found that a method of blowing the inert gas such as N ₂ gas or the reducing gas such as H ₂ into the plating bath at the same time to make it more uniformly stirred is better.

In addition, as a result of examining a method of circulating the plating liquid and stirring it uniformly, plating is performed while placing the plating object in the middle of two opposite electrode plates and flowing the plating liquid suspended therein from the bottom up. The fact turned out. Also in this case, stirring can be further improved by using the introduction of an inert gas or a reducing gas in combination. For example, in the case of a nickel metal layer, an electrochlorination nickel bath, a high chloride nickel bath, and a nickel acetate bath can be employ | adopted.

Although it is preferable to employ | adopt the bath mentioned above in this invention, this invention is not limited to these, Various Ni plating bath can be employ | adopted.

Subsequently, particles containing Ni are dispersed in such a bath. The material and particle diameter of such particles are as described above. However, when Ni is used as the first metal and an alloy with a second metal selected from Al, Zn, Mg, and Sn, caustic alkali treatment as described later is preferable. As such an alloy, it is practical to employ the foregoing and undeveloped Raney-nickel.

In addition, as a particle | grain, when employ | adopting the 1st metal mentioned above and what remove | eliminated at least one part of the 2nd metal from the alloy of a 1st metal and a 2nd metal previously may be employ | adopted, In such a case, it mentions later Caustic alkali treatment is rarely necessary. As such, for example, Raney-Nickel developed can be adopted. In such a case, it is preferable to form an oxide film on the surface of such a particle and to stabilize it for handling.

Specifically, commercially available stabilized Raney-Nickel can be employed. The oxide coating adhering to the above-mentioned particles is reduced and removed with hydrogen generated when the electrode is used as a cathode during electrolysis such as an aqueous alkali chloride solution.

In addition, such an oxide film may be reduced (for example, heated in a hydrogen atmosphere) before use as an electrode.

The ratio of such particles in the bath is preferably 1 g / l to 20 g / l in the sense of improving the adhesion state of the particles to the electrode surface. In addition, it is preferable that the temperature conditions at the time of a dispersion plating operation are 20-80 degreeC, and a current density is 1A / dm <^2> -20A / dm <^2> .

In addition, of course, you may add suitably the additive for distortion reduction, the additive which encourages co-electrode deposition, etc. to a plating bath. It goes without saying that Ni plating may be performed again after heating or dispersion plating in order to further strengthen the adhesion of the particles to the metal layer.

In addition, as described above, in the case of providing an intermediate layer between the electrode core and the metal layer containing particles, the electrode core is first Ni-plated or Cu-plated, and then the dispersion core method and the melt spraying method are used. A metal layer containing particles is formed thereon.

As the plating bath in such a case, various plating baths described above can be employed, and a known plating method can also be used for Cu plating.

In this way, the electrode with particle | grains of this invention is obtained through a metal layer on an electrode core.

Then, if necessary, caustic alkali treatment (for example, immersion in a caustic aqueous alkali solution) is performed to elute and remove at least a part of the metal other than Ni in the metal particles to make the particles porous.

In this case, the concentration of the caustic aqueous alkali solution is preferably 5 to 40% by weight with NaOH, and the temperature is preferably performed under the conditions of 50 ° C to 150 ° C.

Moreover, although it is preferable to perform caustic alkali treatment as mentioned above as particle | grains, you may actually perform electrolysis by attaching the electrode with such particles to an alkali chloride electrolytic cell as it is, without performing caustic alkali treatment.

In this case, in the process of electrolysis, the second metal elutes and the overvoltage of the electrode decreases. However, the produced caustic alkali aqueous solution is slightly contaminated by this eluted 2nd metal ion.

The electrode of the present invention can be employed as an electrode for electrolytic alkali chloride aqueous solution, in particular, a cathode, in addition to electrolytic alkali chloride solution using a porous membrane (for example asbestos diaphragm) and water electrolysis It can also be employed as an electrode.

Next, an embodiment of the present invention will be described.

Example 1

Undeveloped Raney-Nickel alloy powders (Ni 50%, Al 50%, 200 mesh pass) made by Kawaken Fine Chemicals Co., Ltd. in nickel chloride (NiCl ₂ · 6HO ₂ 300g / l, H ₃ BO ₃ 38g / l) At a rate of 20 g / L and while stirring this sufficiently, the Ni plate was plated at a current density of 3 A / dm ² , pH 2.0, and 50 ° C. for 30 minutes, using the Ni plate as the positive electrode and the iron plate (electrode core) as the negative electrode. As a result, a black gray plating layer was formed on the iron plate.

The Ni plating layer was about 80 mu and the Ni—Al alloy particles in the plating layer were about 35%. This was developed for 1 hour at 80 ° C. in 20% NaOH to elute Al. The electric double layer capacity was 18000 μF / cm ² and the hydrogen overvoltage was 60 mV.

Example 2

Undeveloped linyi-nickel alloy powder made by Kawaken Fine Chemicals (Ni 50% in NiSO ₄ · 6H ₂ O 200 g / l, NiCl ₂ 6H ₂ O 175 g / l, H ₃ BO ₃ 40 g / l) , 50% Al, 200 mesh pass) was added at a rate of 20 g / l, while stirring it sufficiently, the Ni plate was used as an anode and the iron plate (electrode core) was used as a cathode at a current density of 2A / dm ² , pH 1.8, and 45 ° C. Time plating was performed. As a result, a black gray plating layer was formed on the iron plate.

The Ni plating layer was about 100 mu and the Ni—Al alloy particles in the plating layer were about 25% by weight.

On the other hand, Al was eluted in the same manner as in Example 1, but the electric double layer capacity was 1500 µF / cm ² and the hydrogen overvoltage was 70 mV.

Example 3

Undeveloped linyi-nickel alloy powder made by Kawaken Fine Chemicals (Ni 50% in nickel chloride, nickel acetate bath (NiCl ₂ · 6H ₂ O 135g / l, Ni (CH ₃ COO) ₂ · 4H ₂ O 105g / l) , 50% Al, 200 mesh pass) was added at a rate of 50 g / l, while stirring it sufficiently, the Ni plate was used as an anode and the iron plate (electrode core) was used as a cathode. The current density was 3A / dm ² , pH 3.0, 30 at 50 ° C. Plating was performed for a minute. As a result, a black gray plating layer was formed on the iron plate.

The Ni plating layer was about 60 mu and the Ni-Al alloy particles in the plating layer were about 30 wt%.

On the other hand, Al was eluted in the same manner as in Example 1, but the electric double layer capacity was 10000 µF / cm ² and the hydrogen overvoltage was 80 mV.

Example 4

Transmission screen nickel bath _{(NiCl 2 · 6H 2 O 300g} / ℓ, H 3 BO 3 38g / ℓ) in Kawagoe kkeng Fine Chemical Co., Ltd. US developed Raney-nickel alloy (Ni 50 wt%, Al 50% by weight) of 10g / ℓ And added to the plating bath of FIG.

In the lower part of the plating bath of FIG. 3, a device capable of moving the porous plate 5 up and down, and simultaneously blowing N ₂ gas downward using the bubbler 6, substantially close to the plated object 9 Plating was carried out by arranging two sheets (7) (8) of Ni anodes having an equal area and placing the plated material (9) in the middle thereof.

The plating temperature is 40 ° C, the pH is 2.0, the stroke of the porous plate is 20% of the height of the liquid, 100 Hz / min, and the N ₂ gas 10 is 10 l / min dm ² of the bottom area of the plating bath. Blown in the amount. The plated material was made of iron xpanme metal as a cathode (electrode core) and plated for 1 hour at a current density of 3 A / dm ² to give a black-gray plated product. The plating layer was about 150 mu, and the proportion of undeveloped Raney-Ni in the plating layer was 30% by weight. The shape of this plated layer was almost the same in each part, and hydrogen overvoltage of each part was used by using a plated plate as a cathode and using a saturated carmel electrode as a reference electrode under a 40 wt% NaOH aqueous solution (90 ° C.) and a current density of 20 A / dm ^2. When measured, all were 100 mV.

Example 5

Nickel chloride bath (NiCl ₂ · 6H ₂ O 300 g / l, H ₃ BO ₃ 38g / l) was injected into the tank 11 of the apparatus shown in FIG. Two Ni anodes 13 and 14 having a size substantially equivalent to that of the to-be-plated object 12 with a pump 16, in which a solution of (50 wt% Ni and 50 wt% Al) was suspended at a rate of 10 g / l. The plating was carried out while transferring to the plating bath 15 in which the plated object 12 was disposed in the middle of the plate while circulating. At this time, the pH of the plating liquid was 2.0, the temperature was 40 ° C., the flux of the plating liquid in the plating bath was 70 cm sec, and the electrodeposited at the current density of 3 A / dm ² for 30 minutes using the iron plate as the plated object (cathode). A black gray plating layer was formed on the substrate. The Ni plating layer was about 70 mu and the proportion of undeveloped Raney-nickel in the plating layer was 33% by weight.

The plated layer had almost the same shape in each part, and after the alkali treatment in the same manner as in Example 4, cutting was performed to measure the hydrogen overvoltage of each part, and all were 90 mV.

Example 6

Example 5 using a nickel chloride bath (NiSO ₄ .6H ₂ O 200 g / l, NiCl ₂ 6H ₂ O 175 g / l, H ₃ BO ₃ 40 g / l) as a plating solution using the apparatus of FIG. 4 used in Example 5. The undeveloped Raney-Ni particles similar to the above were suspended and the plating was carried out while transferring the circulation to the plating tank by a pump. At this time, the pH of the plating solution was controlled to 1.5, the temperature was 50 ° C, the line speed in the plating bath was 85cm / sec, and the electrodeposited at a current density of 3A / dm ² for 30 minutes using the iron plate as the plated material (cathode). A black gray plating layer was formed.

The plating layer was about 100 mu and the proportion of undeveloped Raney-nickel in the plating layer was 40% by weight.

Alkaline treatment of the plated product was carried out in the same manner as in Example 4, and then the fine cuts were made, and the hydrogen overvoltage was measured using each part as a cathode.

Comparative Example 1

Watt bath _{(NiSO 4 · 7H 2 O 300g} / ℓ, NiCl 2 6H 2 O 60g / ℓ, H 3 BO 3 30g / ℓ) in Kawagoe kkeng (川硏) Fine Chemical US deployment (展開前) of Priest Raney-nickel Powder (Ni 50%, Al 50%, average particle diameter: 30μ) was added at a rate of 100 g / L, while stirring sufficiently, the Ni plate was used as the anode and the Cu plate (electrode core) as the cathode. The current density was 3A / dm ² , pH 3.5, Plating of Cu board was performed for 30 minutes on 55 degreeC conditions. As a result, it was confirmed by microscopic observation that a black gray plating layer was obtained on the Cu plate and many fine irregularities existed on the surface. Al was eluted in the same manner as in Example 1.

The electric double layer capacity of the Cu plated as described above was 5000 µF / cm ² . In addition, the electric double layer capacity was immersed in a 40% by weight aqueous solution of NaOH (25 ° C) to insert a platinum-black platinum plate having a surface area 100 times larger than that of the test piece as a counter electrode, and the cell impedance in this state was transferred to the Koolaus bridge. It measured and the electric double layer capacity of the test piece was calculated | required.

The Ni plating layer was about 40 mu and the Ni—Al alloy particles in the plating layer were about 25 wt%.

Next, the electrode potential was measured in the same manner as in Example 4 using the plated Cu plate as the cathode, and as a result, the hydrogen overvoltage was 120 mV.

Comparative Examples 2 to 5

Plating was carried out in almost the same manner as in Comparative Example 1 except that the addition ratio, particle diameter, and plating conditions of undeveloped Raney-nickel of Comparative Example 1 were changed. The results are shown in Table 1. However, in Comparative Example 3, Fe was used as the electrode core, and in Comparative Example 5, SUS 304 was used as the electrode core.

TABLE 1

[Comparative Examples 6-7]

The stabilized Raney-Nickel particles manufactured by Kawaken Fine Chemical Co., Ltd. were used to vary the addition ratio of the particles to the plating bath (the same plating bath as Comparative Example 1), and the dispersion plating was performed in almost the same manner as in Comparative Example 1. Table 2 shows the electric double layer capacity and hydrogen overvoltage of these electrodes. At this time, the specific surface area of the stabilized Raney-nickel was 10.5 m ² / g (value by the lauric acid adsorption method).

TABLE 2

Comparative Example 8

Alcohol pamin bath of Comparative Example 1 and the same non-expanded while (sulfamic acid nickel _{300g / ℓ, NiCl 2 · 6H} 2 O 6g / ℓ, H 3 BO 3 40g / ℓ pH 4.0) Raney-rate of a nickel powder, 50g / ℓ It added so that it might be carried out and plating was performed for 1 hour in the same manner as in Comparative Example 1. Subsequently, it developed for 1 hour in 20% NaOH and 80 degreeC, and Al eluted. The electric double layer capacity of the electrode thus obtained was measured and found to be 12000 µF / cm ² . Using the electrode as a cathode, hydrogen overvoltage was measured under the same conditions as in Example 4, which was 80 mV.

Comparative Example 9

The electrode obtained in Comparative Example 1 was used as a cathode, and TiO ₂ and RuO ₂ were coated with Ti as an anode, and electrolytic work of aqueous NaCl solution was carried out for 400 days in an electrolytic cell in which these anode cathodes were covered with a DuPont Zenap ion membrane. When the durability test of the negative electrode was conducted, the hydrogen overvoltage of the negative electrode was 120 mV-bed and no peeling of the plating layer and particles occurred.

The catholyte had a temperature of 90 ° C. in an aqueous solution of 400 wt%. The electrolytic current density was 20 A / dm ² .

Claims (1)

Components other than nickel after co-electrodepositing particles of Raney-Nickel alloy and nickel metal onto the electrode body from a dispersion obtained by dispersing the Raney-Nickel alloy metal particles in a solution containing at least 135 g / L of NiCl ₂ , 6H ₂ O An electrode having a structure in which the proportion of nickel particles in the metal layer is 5 to 80% by weight by partially eluting the nickel metal layer from which the nickel particles are electrodeposited by eluting.

Images