Preparation method and regeneration method of anode for electrolysis

Abstract

The invention relates to a preparation method and a regeneration method of an anode for electrolysis. The preparation method comprises the following steps: S1, treating the surface of a titanium substrate; s2, the titanium substrate treated in the step S1 is coated with first coating liquid of intermediate bonding layer coating liquid containing three elements of an iridium source, a tantalum source and a platinum source or a ruthenium source, and roasting is conducted after drying; the operation is repeated for 2-15 times; s3, coating the electrode roasted in the step S2 with a catalytic coating solution containing an iridium source and a tantalum source, and roasting after drying; repeating the operation for 15-30 times; and S4, roasting. According to the anode obtained by the preparation and regeneration method provided by the invention, the service life of the electrode is prolonged, the electrolysis voltage is reduced, the service life of the related DSA anode is prolonged, lower electrolysis energy consumption is obtained, the electrolysis efficiency is improved, and the anode is particularly suitable for an electrolytic copper foil. The method provided by the invention also solves the problems of easy oxygen permeation and electrode failure of the anode in the prior art.

Description

Technical Field

[0001] The present invention relates to a preparation method and a regeneration method of an anode for electrolysis, belonging to the technical field of preparation of positive materials. Background Art

[0002] Dimensionally Stable Anode (DSA) is a new type of insoluble anode material. Its base metal is generally industrial pure titanium, and it has a metal oxide coating on the surface. The functions of the coating include low resistivity and good electrical conductivity. As an anode with stable dimensions and low OER overpotential, DSA has high practical value. However, its catalytic oxide coating is limited to IrO2, RuO2, etc. due to the acidic use environment. Since the working conditions of the DSA electrode during the electroplating process are relatively harsh, most metals or metal oxides cannot meet its use conditions. Although IrO2 and RuO2 can be used as high-efficiency catalyst coatings, the stability of the DSA electrode is poor and it is prone to failure. The main reason for the electrode failure is that when the electrode undergoes an oxygen absorption reaction in an acidic electrolyte solution, the catalyst coating gradually dissolves in the acidic electrolyte solution and gradually penetrates deeper through the coating gaps until the titanium substrate. At a higher current density, the titanium substrate is corroded, further leading to an increase in the cell voltage and the shedding of the catalyst coating, resulting in the consumption and inactivation of the catalyst coating, oxidation of the titanium substrate, an increase in the electrolytic cell voltage, causing anode failure, and increasing production costs. Summary of the Invention

[0003] (1) Technical Problems to be Solved

[0004] In order to solve the above problems of the prior art, the present invention provides a preparation method of an anode for electrolysis. The present invention also provides a preparation method of a regenerated coating for the anode. By introducing an intermediate bonding coating, the bonding force between the substrate and the coating is enhanced, the coating stability is improved, and the penetration of the electrolyte into the titanium substrate is slowed down or avoided.

[0005] (2) Technical Solutions

[0006] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0007] A preparation method of an anode for electrolysis, which includes the following steps:

[0008] S1. Treat the surface of the titanium substrate;

[0009] S2. Coat the first coating liquid of the intermediate bonding layer coating liquid containing soluble iridium source, tantalum source and platinum source or ruthenium source on the titanium substrate treated in step S1, dry it and then calcine it; repeat this coating, drying and calcining operation 2 - 15 times; wherein, the molar ratio of iridium, tantalum and platinum or ruthenium in the first coating liquid is (50 - 80):(20 - 50):(5 - 20);

[0010] S3. Coat the catalytic coating liquid containing soluble iridium source and tantalum source on the electrode calcined in step S2, dry it and then calcine it; repeat this coating, drying and calcining operation 15 - 30 times; wherein, the molar ratio of iridium and tantalum in the catalytic coating liquid is (50 - 80):(20 - 50);

[0011] S4. The last calcination.

[0012] For the preparation method as described above, preferably, in step S1, the surface treatment includes degreasing, sandblasting or shot peening the titanium substrate, and then pickling treatment.

[0013] For the preparation method as described above, preferably, the pickling conditions are soaking in 10 - 25% hydrochloric acid for 2 - 3 hours or boiling in 10 - 25% sulfuric acid solution for 2 - 4 hours.

[0014] For the preparation method as described above, preferably, by means of mechanical brushing or electrostatic spraying, coat the intermediate bonding layer coating liquid and the catalyst coating solution evenly on the dried titanium substrate, dry it and then transfer it to a high-temperature furnace for sintering.

[0015] For the preparation method as described above, preferably, in step S2, the iridium source is any one of iridium tetrachloride, iridium trichloride, chloroiridic acid, bromoiridic acid or iridium acetate, the tantalum source is any one of tantalum pentachloride hydrochloric acid solution, tantalum pentachloride n-butanol solution, tantalum ethoxide or tantalum butanediol, the platinum source is any one of chloroplatinic acid and platinum acetate, the ruthenium source is any one of ruthenium acetate, ruthenium trichloride or ruthenium acetate, and the solvent of the first coating liquid is an organic solvent or an inorganic solvent, wherein the organic solvent is one or a mixture of two of n-butanol, isopropanol, ethanol, propylene glycol, ethylene glycol, butanediol, and the inorganic solvent is hydrochloric acid solution; wherein, the mass concentration of the first coating liquid is 10 - 60 g / L.

[0016] The preparation method as described above, preferably, in step S3, the iridium source is any one of iridium tetrachloride, iridium trichloride, iridic acid, hydrobromo-iridic acid or iridium acetate, the tantalum source is any one of tantalum chloride hydrochloric acid solution, tantalum butoxide solution, tantalum ethoxide or tantalum butanediol, and the solvent of the catalytic coating liquid is an organic solvent or an inorganic solvent. The organic solvent is one or a mixture of two of n-butanol, isopropanol, ethanol, propylene glycol, ethylene glycol, butanediol, and the inorganic solvent is hydrochloric acid solution. The mass concentration of the catalytic coating liquid is 10-60 g / L.

[0017] The preparation method as described above, preferably, in steps S2 and S3, the coating method adopts dip coating, manual coating, mechanical transfer coating or spraying and other methods and is not limited to the above methods, and the first coating liquid and the catalyst coating solution are evenly brushed on the titanium substrate.

[0018] The drying conditions are drying at 80-150 °C for 5-20 min; the calcination temperature is 450-520 °C, and the calcination is carried out for 10-40 min.

[0019] The method as described above, preferably, in step S3, the repeated operation is preferably carried out 20-30 times. In step S4, the sintering conditions are maintaining at 450-500 °C for 60 min-120 min.

[0020] A method for regenerating and manufacturing an anode coating for electrolysis, which includes removing scale and cleaning the surface of the failed anode plate using physical or chemical methods, and then carrying out according to the preparation method as described above. Among them, in step S1, the surface treatment further includes thermal straightening treatment after sandblasting treatment.

[0021] Further, the thermal straightening treatment is to put the titanium substrate into a high-temperature furnace, and the temperature and time are heating to 450 °C-550 °C and then maintaining for 1-2 h.

[0022] (III) Beneficial effects

[0023] The beneficial effects of the present invention are:

[0024] The present invention provides a method for preparing an anode for electrolysis. The prepared anode improves the service life of the electrode, reduces the electrolysis voltage, improves the service life of the related DSA anode, obtains lower electrolysis energy consumption, improves the electrolysis efficiency, and is especially suitable for the anode of electrolytic copper foil.

[0025] The present invention also provides a method for manufacturing an anode regeneration, which solves the problems that the anode is prone to oxygen permeation and electrode failure in the prior art. The anode regeneration manufacturing method provided by the present invention can restore the original surface state of the electrode, make the failed electrode restore the catalytic activity of the coating, and at the same time will not cause damage to the titanium substrate, ensuring the installation accuracy requirements of the electrode.

[0026] The anodic regeneration manufacturing method provided by the present invention enables the titanium substrate to be reused multiple times, saving the substrate cost and the substrate manufacturing cost; it also meets the service life requirements of related DSA anodes, fully meets the demand for copper foils used in the production of lithium-ion batteries, and can also meet the demand for copper foils used in the production of printed circuit boards. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the microscopic morphology of the newly prepared electrode under the electron microscope;

[0028] Figure 2 is the microscopic morphology of the regenerated anode under the electron microscope. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The present invention provides a preparation method for an anode used in electrolysis and a manufacturing method for its regenerated anode to solve the technical problem of anode failure in the prior art. Since the cost of the anode titanium substrate is relatively high, the manufacturing cost of the titanium anode mainly includes the material cost of the titanium substrate and the cost of the active coating on the anode surface, among which the material cost of the titanium substrate accounts for 30%-45%. From the perspective of economic benefits, when the electrolytic cell is compared at the same current density, when the economic loss caused by the increase in the cell voltage due to the loss of activity of the coated titanium anode is greater than the cost of anode coating regeneration, the anodic regeneration manufacturing method of the present application can enable the titanium substrate to be reused multiple times, saving the substrate material cost and thus saving the substrate manufacturing cost.

[0030] In the preparation method of the anode for electrolysis and the manufacturing method of the regenerated anode, by introducing the step of preparing an intermediate bonding coating, the effect of enhancing the bonding force between the substrate and the catalytic active coating can be achieved. The intermediate bonding coating contains iridium tantalum platinum or iridium tantalum ruthenium, which can enhance the bonding force between the substrate and the catalytic coating, improve the coating stability, and slow down or avoid the penetration of the electrolyte into the titanium substrate.

[0031] Among them, for the catalytic active coating, by roasting, iridium tantalum binary oxide is selected. Adding non-conductive Ta2O5 to conductive IrO2 can play a role in improving the anode stability.

[0032] To better explain the present invention for easy understanding, the present invention will be described in detail below with reference to the accompanying drawings through specific embodiments.

[0033] Example 1

[0034] A preparation method for an anode used in electrolysis includes the following steps:

[0035] S1. Treat the surface of the titanium substrate; the surface treatment includes surface degreasing, sandblasting treatment, and pickling treatment; among them, for the pickling treatment, specifically, soak in 10% hydrochloric acid for 2 hours, and after pickling, wash the titanium substrate with clear water 3 times and perform drying treatment.

[0036] S2. Preparation of the first coating liquid for forming the intermediate bonding layer: The iridium source, tantalum source, and ruthenium source are mixed according to a molar ratio of iridium, tantalum, and ruthenium elements of 60:40:10. The iridium source, tantalum source, and ruthenium source are respectively dissolved in the organic solvent n-butanol as chloro iridic acid, tantalum ethoxide, and ruthenium acetate according to the above ratio for use. The total mass concentration of chloro iridic acid, tantalum ethoxide, and ruthenium acetate is 50 g / L.

[0037] S3. Preparation of the second coating liquid for forming the catalytic coating; Chloro iridic acid and tantalum ethoxide are dissolved in the organic solvent propylene glycol according to a molar ratio of iridium and tantalum elements of 70:30 for use. The mass concentration of the second coating liquid is 60 g / L.

[0038] S4. The prepared first coating liquid is evenly coated on the dried titanium substrate, dried at 100 °C for 15 min, calcined in a muffle furnace at 500 °C for 20 min after drying, taken out and cooled to room temperature, and the above operation is repeated. This step is repeated 10 times.

[0039] S5. The prepared second coating liquid is evenly brushed on the electrode of the intermediate bonding coating treated in step S4, dried at 100 °C for 15 min, then calcined in a muffle furnace at 520 °C for 20 min, taken out and cooled to room temperature for the next brushing. This step is repeated 25 times, and finally kept warm in a muffle furnace at 480 °C for 60 min to prepare a multi-precious metal oxide anode.

[0040] Example 2

[0041] A preparation method of an anode for electrolysis, which includes the following steps:

[0042] S1. Treat the surface of the titanium substrate; The surface treatment includes surface degreasing, sandblasting treatment, and pickling treatment; Among them, the pickling treatment is specifically soaking in 10% hydrochloric acid for 2 hours, washing the pickled titanium substrate with clean water 3 times, and drying treatment.

[0043] S2. Preparation of the first coating liquid, that is, the intermediate bonding layer coating liquid: The iridium source, tantalum source, and platinum source are in a molar ratio of 60:40:10. The iridium source, tantalum source, and platinum source are respectively dissolved in the organic solvent n-butanol as chloro iridic acid, tantalum ethoxide, and H2PtCl6 according to the above ratio for use. The total mass concentration of chloro iridic acid, tantalum ethoxide, and H2PtCl6 is 50 g / L.

[0044] S3. Preparation of the catalytic coating liquid; Chloro iridic acid and tantalum ethoxide are dissolved in the organic solvent propylene glycol according to a molar ratio of iridium and tantalum elements of 70:30 for use. The total mass concentration of chloro iridic acid and tantalum ethoxide is 60 g / L.

[0045] S4. Uniformly brush the prepared first coating liquid onto the dried titanium substrate, bake it in a muffle furnace at 500 °C for 20 min after drying, take it out and cool it to room temperature for the next brushing, and repeat this step 10 times.

[0046] S5. Uniformly brush the prepared catalytic coating liquid onto the electrode of the intermediate bonding coating treated in step S4, dry it at 100 °C for 15 min, then bake it in a muffle furnace at 520 °C for 20 min, take it out and cool it to room temperature for the next brushing, repeat this step 25 times, and finally keep it warm in a muffle furnace at 480 °C for 60 min to prepare a multi-precious metal oxide anode.

[0047] The obtained microscopic morphology of the electrode by electron microscopy is as Figure 1 shown.

[0048] Example 3

[0049] A preparation method of a regenerated anode, which includes the following steps:

[0050] 1. Treat the scale formed on the surface of the failed anode plate in the electrolyte, such as compounds of lead, iron, calcium, etc., by physical or chemical methods. The physical method is ultrasonic method or using tools such as brushes, and the chemical method is to soak it with 10-20% hydrochloric acid. Then, use sandblasting or shot peening to remove the old coating of the cleaned failed electrode completely, exposing the titanium substrate.

[0051] 2. Perform sandblasting treatment and thermal straightening treatment on the anode after cleaning treatment; the conditions for thermal straightening are 500 °C, and keep it warm for 1.5 h after heating to the target temperature.

[0052] 3. Perform pickling treatment on the sandblasted titanium substrate: soak it with 10-20% hydrochloric acid for 2-3 hours or boil it with 10-25% sulfuric acid for 2-4 hours;

[0053] 4. Perform pure water cleaning and drying on the pickled titanium substrate;

[0054] 5. Preparation of the first coating liquid, i.e., the intermediate bonding layer coating liquid: The iridium source, tantalum source, and platinum source are in a molar ratio of iridium:tantalum:platinum elements of 60:40:10. The iridium source, tantalum source, and platinum source are made with chloroiridic acid, tantalum pentachloride n-butyl alcohol, and platinum acetate, and are dissolved in the organic solvent n-butyl alcohol according to the above ratio for use. The total mass concentration of chloroiridic acid, tantalum pentachloride n-butyl alcohol, and platinum acetate is 50 g / L.

[0055] 6. Prepare the catalytic coating active liquid: According to a molar ratio of iridium and tantalum elements of 70:30, dissolve chloroiridic acid and tantalum pentachloride n-butyl alcohol solution in the organic solvent propylene glycol for use. The total mass concentration of chloroiridic acid and tantalum pentachloride is 60 g / L.

[0056] 7. Brush the prepared intermediate bonding layer coating liquid evenly onto the dried titanium substrate, bake it in a muffle furnace at 500 °C for 20 min after drying, take it out and cool it to room temperature for the next coating, and repeat the above steps 10 times.

[0057] 8. Brush the prepared catalytic coating active liquid evenly onto the electrode with the intermediate bonding layer, bake it in a muffle furnace at 520 °C for 20 min after drying, take it out and cool it to room temperature for the next coating, repeat the above steps 25 times, and finally keep it warm in a muffle furnace at 480 °C for 60 min to prepare a multi-component noble metal oxide anode.

[0058] Comparative Example 1

[0059] 1. Treat the surface of the titanium substrate; the surface treatment includes surface degreasing, sandblasting treatment, and pickling treatment; among them, the pickling treatment is specifically soaking in 10 - 20% hydrochloric acid for 3 hours. Wash the pickled titanium substrate with clean water 3 times and perform drying treatment.

[0060] 2. Preparation of the catalytic coating liquid; according to the molar ratio of iridium to tantalum of 70:30, dissolve chloroiridic acid and tantalum pentachloride n-butyl alcohol solution in propylene glycol for use, and the mass concentration of chloroiridic acid and tantalum pentachloride is 60 g / L.

[0061] 3. Brush the prepared catalytic coating liquid evenly onto the treated titanium substrate, dry it at 100 °C for 15 min, bake it in a muffle furnace at 520 °C for 20 min after drying, take it out and cool it to room temperature for the next coating, repeat the above steps 35 times, and finally keep it warm in a muffle furnace at 480 °C for 60 min to prepare a binary noble metal oxide anode.

[0062] The SEM micro-morphology of the electrode prepared in Comparative Example 1 is as Figure 2 shown.

[0063] In order to study the performance of the coating, the electrolysis potential of the electrode coatings obtained in the examples and comparative examples was detected. The potential was detected at a current density of 6000 A / m 2 The detection results are shown in Table 1, and the electrolysis potential of the examples is lower than that of the comparative examples.

[0064] Table 1 Electrolysis potential values of the electrode coatings in the examples and comparative examples

[0065] Test electrode Electrolysis potential value (V) Example 1 1.218 Example 2 1.222 Example 3 1.231 Comparative example 1.234

[0066] The electron microscopic results show that the oxide on the surface of the electrode coating prepared in the embodiments and comparative examples provided by the present invention presents a fine, velvety morphology, with a good degree of crystallization, and can provide a number of active dense sites during the electrolysis reaction. Compared with the comparative example electrode, the electrode with the intermediate binding layer of the present invention has a large number of microscopic non-penetrating, cracked lines on the surface of the electrode coating, which can increase the specific surface area during the electrolysis process, further reduce the electrolysis potential during the electrolysis process, and reduce the cell voltage during the electrolysis process.

[0067] Compared with the electrode prepared in the comparative example, the electrode prepared in the embodiment provided by the present invention has a lower electrolysis potential value of the electrode with the intermediate bonding layer. The prepared electrode contains an iridium tantalum platinum or iridium tantalum ruthenium intermediate bonding coating, which can enhance the bonding force between the substrate and the catalytic coating, improve the stability of the coating, slow down or prevent the electrolyte from penetrating into the titanium substrate, further optimize the microstructure of the coating, improve the uniformity and density of the coating surface, improve the electrochemical properties of the electrode, and thereby reduce the resistance of the electrode and improve the current efficiency.

[0068] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any person skilled in the art can use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing an anode for electrolysis, characterized in that, It includes the following steps: S1. Treat the surface of the titanium substrate; S2. Coat the first coating liquid of the intermediate bonding layer coating liquid containing three elements of iridium source, tantalum source and platinum source or ruthenium source on the titanium substrate treated in step S1, dry it and then calcine it; repeat this operation 2 - 15 times; wherein, the molar ratio of iridium, tantalum and platinum or ruthenium elements in the first coating liquid is 50 - 80:20 - 50:5 - 20; S3. Coat the catalytic coating liquid containing iridium source and tantalum source on the electrode calcined in step S2, dry it and then calcine it; repeat this operation 15 - 30 times; wherein, the molar ratio of iridium and tantalum elements in the catalytic coating liquid is 50 - 80:20 - 50; S4. Calcine.

2. The preparation method according to claim 1, characterized in that, In step S1, the surface treatment includes degreasing, sandblasting or shot peening the surface of the titanium substrate, and then pickling treatment.

3. The preparation method according to claim 2, characterized in that, The pickling conditions are soaking in 10 - 25% hydrochloric acid for 2 - 3 hours or boiling in 10 - 25% sulfuric acid solution for 2 - 4 hours.

4. The preparation method according to claim 1, characterized in that, In step S2, the iridium source is any one of iridium tetrachloride, iridium trichloride, iridic acid, bromoiridic acid or iridium acetate, the tantalum source is any one of tantalum pentachloride hydrochloric acid solution, tantalum pentachloride n-butanol solution, tantalum ethanolate or tantalum butanediolate, the platinum source is any one of chloroplatinic acid and platinum acetate, the ruthenium source is any one of ruthenium acetate, ruthenium trichloride or ruthenium acetate, the solvent of the first coating liquid is an organic solvent or an inorganic solvent, wherein the organic solvent is one or a mixture of two of n-butanol, isopropanol, ethanol, propylene glycol, ethylene glycol and butanediol, and the inorganic solvent is hydrochloric acid solution; wherein, the mass concentration of the first coating liquid is 10 - 60 g / L.

5. The preparation method according to claim 1, wherein The coating method adopts dip coating, manual coating, mechanical transfer coating or spraying method to uniformly coat the first coating liquid and the catalyst coating solution on the titanium substrate.

6. The preparation method according to claim 1, wherein In step S3, the iridium source is any one of iridium tetrachloride, iridium trichloride, iridic acid, bromoiridic acid or iridium acetate, the tantalum source is any one of tantalum chloride hydrochloric acid solution, n-butanol tantalum solution, tantalum ethanolate or tantalum butanediolate, the solvent of the catalytic coating liquid is an organic solvent or an inorganic solvent, wherein the organic solvent is one or a mixture of two of n-butanol, isopropanol, ethanol, propylene glycol, ethylene glycol and butanediol, and the inorganic solvent is hydrochloric acid solution; the mass concentration of the catalytic coating liquid is 10 - 60 g / L.

7. The preparation method according to claim 1, characterized in that, In steps S2 and S3, the drying condition is drying at 80 - 150°C for 5 - 20 min; the calcination temperature is 450 - 520°C, and the calcination time is 10 - 40 min.

8. The preparation method according to claim 1, characterized in that, In step S3, the number of coating times is 20 - 30 times. In step S4, the sintering condition is heat preservation at 450 - 500°C for 60 min - 120 min.

9. A method for regenerating and manufacturing an anode coating for electrolysis, which includes descaling and cleaning the surface of a failed anode plate using a physical method or a chemical method, and then proceeding according to the preparation method described in any one of claims 1-8, wherein, In step S1, after sandblasting treatment, the surface treatment further includes thermal straightening treatment.

10. The method for regenerating and manufacturing the anode coating for electrolysis according to claim 9, characterized in that, The temperature and time of the thermal straightening annealing treatment are heat preservation at 450°C - 550°C for 1 - 2 h.

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