Electrodes and methods of use and manufacture thereof
Patent Information
- Application Number
- JP2024535328
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-01-27
- Filing Date
- 2023-01-17
- Publication Date
- 2026-01-09
AI Technical Summary
Conventional titanium electrodes used in electrowinning processes suffer from high chloride ion-induced corrosion, leading to delamination of the catalyst layer and reduced lifespan due to increased corrosion rates.
The electrodes incorporate a titanium alloy substrate with a corrosion inhibitor, an intermediate titanium-tantalum alloy layer, and an iridium oxide or iridium-tantalum mixed oxide catalyst layer, optimized with specific mass ratios and loadings to enhance corrosion resistance.
The improved electrodes exhibit significantly reduced corrosion rates and extended lifespan, with the addition of corrosion inhibitors and intermediate layers effectively preventing chloride ion penetration and maintaining structural integrity.
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Abstract
Description
[Technical Field]
[0001] This application relates to the field of electrochemistry, particularly but not exclusively to electrodes and methods of their use and manufacture. [Background technology]
[0002] Electrowinning, which is primarily used for electrowinning and purifying metals from their solutions, is an important branch of the electrochemical industry. Metal electrowinning processes, such as the electrolysis of nickel metal, zinc metal, and manganese metal, typically use aqueous solutions containing a certain concentration of chloride ions as the electrolyte. The electrowinning process requires an insoluble anode to form a stable circuit and a continuous electrolysis current.
[0003] Titanium electrodes, as environmentally friendly insoluble anodes, have been widely used in the electrochemical industry, primarily for electrochemical water treatment, metal element extraction, electroplating, and other finishing processes. Titanium electrodes are primarily composed of a titanium metal or titanium alloy substrate and a precious metal oxide catalyst layer on its surface. The substrate provides electrical and mechanical support. Meanwhile, the catalyst layer's oxidation-reduction process significantly reduces the oxygen evolution potential, saving energy. Furthermore, its extremely low electrochemical consumption rate allows the anode to have a relatively long lifespan.
[0004] Conventional electrolytes contain high concentrations of chloride ions, which increase the corrosion rate of the substrate. Once the substrate is severely damaged by corrosion, the catalyst layer peels off from the substrate (as shown in Figure 1), causing the anode to fail and shortening its lifespan. Figure 1 shows the corrosion of the titanium substrate observed through a cross-section of an existing anode. The anode was removed from service after 3 and 6 months, respectively, and the cross-section was observed. The arrow indicates the titanium substrate / catalytic layer interface. Summary of the Invention
[0005] The following provides a brief summary of the subject matter detailed herein, which is not intended to limit the scope of protection of the claims.
[0006] To overcome the shortcomings in the prior art, the inventors of the present application have, after years of careful research, improved the corrosion resistance of electrodes.
[0007] The present application provides an electrode comprising a metal substrate and a catalytic layer. The electrode has at least one of the following characteristics: i) the substrate is a titanium alloy containing a corrosion inhibitor. The corrosion inhibitor is selected from at least one metal selected from platinum, palladium, osmium, iridium, ruthenium, rhodium, tantalum, zirconium, and niobium. The content of the corrosion inhibitor is 0.05 wt% to 0.5 wt% of the total mass of the alloy. ii) the catalytic layer is an iridium oxide layer or an iridium-tantalum mixed oxide layer, and the mass ratio of iridium to tantalum is 1:4 to 1:0. iii) an intermediate layer is disposed between the substrate and the catalytic layer. The intermediate layer is a titanium-tantalum alloy layer.
[0008] In some embodiments, the corrosion inhibitor may be selected from ruthenium and / or palladium, and may also be selected from palladium.
[0009] In some embodiments, the corrosion inhibitor content can be between 0.12 wt% and 0.25 wt% of the total mass of the alloy.
[0010] In some embodiments, the titanium alloy containing the corrosion inhibitor may further include one or more of the following elements: H, N, C, O, and Fe.
[0011] In some embodiments, the titanium alloy containing a corrosion inhibitor can further include, based on the total weight of the alloy, 0.015 wt% H, 0.03 wt% N, 0.08 wt% C, 0.18 wt% O, 0.020 wt% Fe, 0.05 wt%-0.5 wt% corrosion inhibitor, and the balance of Ti.
[0012] In some embodiments, the electrode can further include a catalyst base layer located between the substrate and the catalyst layer or between the intermediate layer and the catalyst layer.
[0013] In some embodiments, the catalytic base layer may comprise a tantalum oxide layer.
[0014] In some embodiments, the tantalum loading in the tantalum oxide layer is 1 g / m 2 ~3g / m 2 It can be said that:
[0015] In some embodiments, the tantalum loading in the tantalum oxide layer is 3 g / m 2 It can be said that:
[0016] In some embodiments, the intermediate layer can include 40 wt% to 60 wt% titanium and 40 wt% to 60 wt% tantalum, based on the total weight of the intermediate layer.
[0017] In some embodiments, the intermediate layer can include 60 wt% titanium and 40 wt% tantalum, based on the total weight of the intermediate layer.
[0018] In some embodiments, the loading of iridium in the catalyst layer is 2 g / m 2 ~20g / m 2 2g / m 2 ~10g / m 2 But 5g / m 2 That's fine too.
[0019] The present application further provides a use of the electrode: The electrode is used for electrowinning, electrosynthesis, metal plating, metal foil production, or printed circuit board production.
[0020] In some embodiments, the electrowinning, electrosynthesis, metal plating, metal foil production, or printed circuit board production can include electrowinning, electrosynthesis, metal plating, metal foil production, or printed circuit board production for the metals nickel, copper, cobalt, zinc, silver, gold, or manganese.
[0021] In some embodiments, the electrode can be used as an insoluble anode for electrowinning.
[0022] The present application further provides a method for manufacturing an electrode, the method comprising the steps of providing an electrode substrate and forming a catalyst layer, and optionally further comprising the step of forming an intermediate layer on the substrate before the step of forming the catalyst layer.
[0023] In some embodiments, the catalyst layer can be formed by a paint-thermal decomposition method or a plasma spray method.
[0024] In some embodiments, the catalyst layer can be formed by applying a coating solution containing iridium or a coating solution containing iridium and tantalum to coat the surface of the substrate or the surface of the intermediate layer, followed by drying and sintering.
[0025] In some embodiments, the intermediate layer can be formed on the substrate by chemical vapor deposition or physical vapor deposition.
[0026] In some embodiments, the intermediate layer can be formed by magnetron sputtering.
[0027] In some embodiments, the method can further include forming a catalyst base layer on the substrate or on the intermediate layer prior to the step of forming the catalyst layer.
[0028] In some embodiments, the catalytic base layer may be formed by a paint pyrolysis process or a plasma spray process.
[0029] Compared with the prior art, the present application has the following beneficial effects: The corrosion resistance of the electrode of the present invention is significantly improved, its lifespan is extended, and its manufacturing cost is reduced.
[0030] Other features and advantages of the present application will be set forth in the description that follows, and in part will be obvious from the description, or may be learned by the practice of the present application. Other advantages of the present application may be realized or obtained by the solutions described and illustrated in the drawings.
[0031] The accompanying drawings are used for understanding the technical solution of the present application and constitute a part of the specification, and are used to explain the technical solution of the present application together with the embodiments of the present application, and do not constitute limitations on the technical solution of the present application. [Brief explanation of the drawings]
[0032] [Figure 1] FIG. 1 illustrates corrosion of the titanium substrate of a prior art electrode. [Figure 2] 1 is a schematic diagram of an electrode structure according to an embodiment of the present application; [Figure 3] 1 is a graph of the results of accelerated life testing of electrodes of Examples 1 and 2 of the present application. DETAILED DESCRIPTION OF THE INVENTION
[0033] In order to clarify the objectives, technical solutions and advantages of the present application, the embodiments of the present application are described in detail below in conjunction with the drawings, and the embodiments and features of the embodiments can be arbitrarily combined as long as there is no contradiction.
[0034] One embodiment of the present application provides an electrode, which includes a substrate 1, an optional intermediate layer 3, an optional catalyst base layer 22, and a catalyst layer 21, stacked in this order from bottom to top, as shown in Figure 2, for example.
[0035] The substrate 1 may be symmetrically provided with an intermediate layer 3 and a catalyst layer 21 on its two sides. Alternatively, the substrate 1 may be provided with an intermediate layer 3 and a catalyst layer 21 on one side and only a catalyst layer 21 on the other side. Alternatively, the substrate 1 may not be provided with an intermediate layer 3 on both sides.
[0036] The catalyst layer 21 may include multiple catalyst layer units, for example, two, three, four or more units. The number of units in the catalyst layer 21 on both sides of the substrate may be the same or different.
[0037] Conventional electrode substrates are metallic titanium, such as GR1 grade commercially pure titanium and GR2 grade commercially pure titanium.
[0038] The electrode substrate of the present application employs a titanium alloy containing a corrosion inhibitor. The corrosion inhibitor may be selected from metals such as platinum group metals, tantalum, zirconium, and niobium, for example, at least one of platinum, palladium, osmium, iridium, ruthenium, rhodium, tantalum, zirconium, and niobium. The content of the corrosion inhibitor is 0.05 wt% to 0.5 wt%, for example, 0.08 wt%, 0.10 wt%, 0.12 wt%, 0.13 wt%, 0.15 wt%, 0.18 wt%, 0.20 wt%, 0.23 wt%, 0.25 wt%, 0.30 wt%, 0.35 wt%, 0.40 wt%, 0.45 wt%, etc., based on the total mass of the alloy. The addition of a specific corrosion inhibitor to metallic titanium can significantly improve the corrosion resistance of the substrate.
[0039] The corrosion inhibitor-containing titanium alloy may further include one or more of H, N, C, O, and Fe, for example, 0.015 wt% H, 0.03 wt% N, 0.08 wt% C, 0.18 wt% O, 0.020 wt% Fe, 0.05 wt%-0.5 wt% corrosion inhibitor, and the balance Ti.
[0040] In another embodiment, the catalytic layer used herein is an iridium oxide layer or an iridium-tantalum mixed layer. To improve the chloride ion corrosion resistance of the catalytic layer in an electrolytic nickel environment, the content of iridium element in the catalytic layer is increased herein. As a result, the mass ratio of iridium element to tantalum element is 1:4 to 1:0, such as 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc. Optimizing the iridium to tantalum content ratio reduces chloride ion penetration into the electrode substrate, lowers the corrosion rate of the substrate, improves the corrosion resistance of the catalytic layer, and extends the life of the electrode.
[0041] The loading of iridium in the catalyst layer was 2 g / m 2 ~20g / m 2 For example, 5 g / m 2 , 8g / m 2 , 10g / m 2 , 13g / m 2 , 15g / m 2 , 17g / m 2 , 20g / m 2 etc.
[0042] In another embodiment, an intermediate layer can be disposed between the substrate and the catalytic layer to protect the interface between the catalytic layer and the substrate and inhibit corrosion at the interface. The intermediate layer can be a titanium-tantalum alloy layer. The titanium-tantalum alloy layer can contain 40 wt% to 60 wt% titanium and 40 wt% to 60 wt% tantalum, based on the total mass of the intermediate layer, for example, 45 wt% titanium and 55 wt% tantalum, 50 wt% titanium and 50 wt% tantalum, 55 wt% titanium and 45 wt% tantalum, etc. In the metal electrowinning process, the chloride ions contained therein are highly corrosive to the interface. Furthermore, the titanium-tantalum alloy intermediate layer provides better corrosion resistance and results in a very low corrosion rate.
[0043] The electrode of the present application may further include a catalyst base layer located between the substrate and the catalyst layer, or between the intermediate layer and the catalyst layer. The catalyst base layer has a tantalum loading of 1 g / m 2 ~3g / m 2 For example, 1.5 g / m 2 , 2g / m 2 , 2.5g / m 2 The tantalum oxide layer may include a tantalum oxide layer, such as
[0044] The electrode of the present application can use a titanium alloy containing the above-mentioned corrosion inhibitor as the electrode substrate and can also include the above-mentioned intermediate layer. The electrode of the present application can use a titanium alloy containing the above-mentioned corrosion inhibitor as the electrode substrate and can also use the above-mentioned iridium oxide layer or iridium-tantalum mixed layer as the catalytic layer. The electrode of the present application can also include the above-mentioned intermediate layer and can also use the above-mentioned iridium oxide layer or iridium-tantalum mixed layer as the catalytic layer. The electrode of the present application can use a titanium alloy containing the above-mentioned corrosion inhibitor as the electrode substrate, can also include the above-mentioned intermediate layer and can also use the above-mentioned iridium oxide layer or iridium-tantalum mixed layer as the catalytic layer. All of these solutions may or may not include a catalytic base layer.
[0045] To fabricate the electrode of the present application, the catalyst layer can be formed by methods such as paint pyrolysis or plasma spraying. The intermediate layer can be formed by methods such as chemical vapor deposition or physical vapor deposition, e.g., magnetron sputtering. The catalyst base layer can be formed by methods such as paint pyrolysis or plasma spraying.
[0046] First, an electrode substrate is prepared. The electrode substrate can be a titanium alloy containing the corrosion inhibitor described above. Optionally, an intermediate layer is formed on the substrate. The intermediate layer can be the titanium-tantalum alloy layer described above. The intermediate layer can be formed on the substrate by magnetron sputtering. Optionally, a catalytic base layer is formed on the substrate or the intermediate layer. The catalytic base layer can be the tantalum oxide layer described above. The catalytic base layer can be formed by applying a coating solution containing tantalum to coat the surface of the substrate or the intermediate layer, followed by drying and sintering. The catalytic layer is formed on the substrate, the intermediate layer, or the catalytic base layer. Optionally, the catalytic layer can be the iridium oxide layer or the iridium-tantalum oxide mixed layer described above. The catalytic layer can be formed by applying a coating solution containing iridium or a coating solution containing iridium and tantalum to coat the surface of the substrate, the intermediate layer, or the catalytic base layer, followed by drying and sintering.
[0047] The electrode of the present application can be used in fields such as electrowinning, electrosynthesis, metal plating, metal foil production, or printed circuit board production. Electrowinning, electrosynthesis, metal plating, metal foil production, and printed circuit board production include electrowinning, electrosynthesis, metal plating, metal foil production, and printed circuit board production for metals such as nickel, copper, cobalt, zinc, silver, gold, and manganese. The electrode can be used as an insoluble anode for electrowinning.
[0048] Example 1 The electrode substrate was made of GR1 grade titanium. The specific components are shown in Table 1.
[0049] The catalyst layer used was iridium tantalum oxide, in which the mass ratio of iridium to tantalum was 4:1. The steps were as follows: First, the electrode substrate was degreased and heat-treated in air at 500°C for 25 minutes, and then pickled in a 6.5 mol / L hydrochloric acid solution containing 40 g / L of dissolved titanium at 90°C for 1.5 hours to obtain an active surface. The product was used as the electrode substrate to be coated.
[0050] The surface of the pickled electrode substrate was coated with a brush using an n-butyl alcohol solution of tantalum ethoxide with a mass concentration of 6% tantalum, then dried at room temperature for 15 minutes, and then sintered in air at 500°C for 25 minutes in an electric furnace. After sintering, the resulting product was removed and cooled. The above tantalum loading process was repeated, each time increasing the loading amount of tantalum to 1 g / m. 2 The total loading of tantalum element is 3g / m 2 Thus, a catalyst base layer was obtained.
[0051] The coating solution used for the catalyst layer was a n-butyl alcohol solution of chloroiridic acid (containing 37% concentrated hydrochloric acid at 6 wt% of the total mass of the coating solution) and tantalum ethoxide. In this solution, the mass concentration of elemental iridium was 6.5%, and the mass concentration of elemental tantalum was 1.63%. The coating solution was coated on the surface of the catalyst base layer, then dried at room temperature for 15 minutes, and then sintered in air at 450°C for 25 minutes in an electric furnace. After sintering, the obtained product was removed and cooled. The above iridium-tantalum loading process was repeated, each time with an elemental iridium loading amount of 1 g / m. 2 , the loading amount of tantalum element is 0.25g / m 2 The total loading of iridium element is 5g / m 2 , with a total tantalum element loading of 1.25 g / m 2In this way, a catalyst layer of an electrode was obtained.
[0052] The electrodes were fabricated.
[0053] Example 2 A titanium alloy containing palladium, which has higher corrosion resistance, was used as the electrode substrate. The specific components are shown in Table 1.
[0054] The same manufacturing process and coating amount as in Example 1 were used to manufacture the catalyst base layer and catalyst layer.
[0055] [Table 1]
[0056] Performance Test
[0057] 1. Corrosion rate of electrode substrate The corrosion rates of the electrode substrates of Examples 1 and 2 were measured at 90°C in 8.0 mol / L hydrochloric acid containing 8.5 g / L of dissolved titanium.
[0058] The corrosion rate of the titanium alloy substrate used in Example 1 was 1.9 g / m 2 The corrosion rate of the titanium substrate containing palladium used in Example 2 was 1.1 g / m 2 Thus, it can be seen that the corrosion rate of the substrate material of Example 2 of the present application was significantly reduced by further adding palladium.
[0059] 2. Accelerated Life Test FIG. 3 shows the change in cell voltage during accelerated life testing for the electrodes prepared in Examples 1 and 2 of the present application. The conditions for the accelerated life test were as follows: the electrolyte was 25% H2SO4 with NaCl (16.7 g / L initially, with 8.3 g / L added twice a week), the current was 20,000 A / m2, and the temperature was 50°C.
[0060] As can be seen from Figure 3 and Table 2, the lifespan of the electrodes in both Example 1 and Example 2 of the present application was extended. In Example 2 of the present application, because palladium was further added to the substrate, the lifespan of the electrode produced was extended by 85% compared to the lifespan of the electrode in Example 1. Thus, it can be seen that the addition of palladium in Example 2 improved the corrosion resistance of the titanium substrate, thereby more effectively improving the lifespan of the electrode.
[0061] Example 3 Using the substrate material of Example 1, a catalyst base layer and a catalyst layer were fabricated on the substrate using the same fabrication process as in Example 1. In the coating solution for the catalyst layer, the mass concentration of iridium element was constant at 6.5 wt%, and the mass concentration of tantalum element was adjusted to 0.72 wt%. The iridium-tantalum loading process was repeated, with the iridium loading amount set to 1 g / m each time. 2 The final catalyst layer had an iridium loading of 5 g / m 2 , tantalum element loading 0.56g / m 2 had.
[0062] Performance Test
[0063] The above-mentioned accelerated life test was carried out. As can be seen from Table 2, the life of the electrode of Example 3 of the present application was also extended. This life was 29% longer than that of the electrode of Example 1. In Example 3, the proportion of iridium in the catalyst layer was increased. This reduced the penetration of chloride ions into the electrode substrate, reduced the corrosion rate of the substrate, and more effectively improved the life of the electrode.
[0064] Example 4 Using the substrate material of Example 1 and an alloy target with a titanium to tantalum weight ratio of 1:1, magnetron sputtering was performed to sputter an intermediate layer of titanium / tantalum (60 / 40 wt%) alloy onto the substrate. The total weight of the resulting titanium-tantalum alloy layer was 10 g / m 2 It was.
[0065] Using the same manufacturing process and coating amount as in Example 3, a catalyst layer was manufactured on the intermediate layer.
[0066] Performance Test
[0067] The above-mentioned accelerated life test was carried out. As can be seen from Table 2, the life of the electrode of Example 4 of the present application was also extended. This life was 44% longer than that of the electrode of Example 1. In Example 4, a titanium-tantalum alloy was used as the intermediate layer, which more effectively improved the life of the electrode.
[0068] [Table 2]
[0069] Although the embodiments disclosed in the present application are as described above, the described contents are merely embodiments adopted for the convenience of understanding the present application and do not limit the present application. A person skilled in the art to which the present application pertains may make any modifications and changes to the form and details of the embodiments without departing from the spirit and scope disclosed by the present application. However, the scope of patent protection of the present application shall still be subject to the scope defined by the appended claims. [Explanation of symbols]
[0070] 1 Base material 21 Catalyst layer 22 Catalyst base layer 3. Middle class
Claims
1. An electrode comprising a metal substrate and a catalyst layer, The electrodes have the following characteristics: i) the substrate is a titanium alloy containing a corrosion inhibitor, the corrosion inhibitor being selected from at least one metal selected from platinum, palladium, osmium, iridium, ruthenium, rhodium, tantalum, zirconium, and niobium, and the content of the corrosion inhibitor is 0.05 wt % to 0.5 wt % of the total mass of the alloy; ii) the catalyst layer is an iridium oxide layer or an iridium oxide-tantalum mixed layer, and the mass ratio of iridium element to tantalum element is 1:4 to 1:0; iii) an intermediate layer disposed between the substrate and the catalyst layer, the intermediate layer being a titanium-tantalum alloy layer.
2. 2. The electrode of claim 1, wherein the corrosion inhibitor is selected from ruthenium and / or palladium.
3. 2. The electrode of claim 1, wherein the content of the corrosion inhibitor is 0.12 wt % to 0.25 wt % of the total mass of the alloy.
4. 3. The electrode of claim 2, wherein the titanium alloy containing the corrosion inhibitor further comprises one or more of the elements H, N, C, O, and Fe.
5. 5. The electrode of claim 4, wherein the titanium alloy containing the corrosion inhibitor comprises, based on the total weight of the alloy, 0.015 wt. % H, 0.03 wt. % N, 0.08 wt. % C, 0.18 wt. % O, 0.020 wt. % Fe, 0.05 wt. % to 0.5 wt. % corrosion inhibitor, and the balance Ti.
6. the electrode further comprises a catalyst base layer, the catalyst base layer being located between the substrate and the catalyst layer or between the intermediate layer and the catalyst layer; The electrode of claim 1 , wherein the catalytic underlayer comprises a tantalum oxide layer.
7. The tantalum loading in the tantalum oxide layer is 1 g / m ２ ~3g / m ２ 7. The electrode of claim 6, wherein:
8. 10. The electrode of claim 1, wherein the intermediate layer comprises 40 wt% to 60 wt% titanium and 40 wt% to 60 wt% tantalum, based on the total weight of the intermediate layer.
9. 9. The electrode of claim 8, wherein the intermediate layer comprises 60 wt% titanium and 40 wt% tantalum.
10. The loading amount of iridium in the catalyst layer is 2 g / m ２ ~20g / m ２ 2. The electrode of claim 1 , wherein:
11. The loading amount of iridium in the catalyst layer is 2 g / m ２ ~10g / m ２ 11. The electrode of claim 10, wherein:
12. 10. Use of the electrode of claim 1, wherein the electrode is used for electrowinning, electrosynthesis, metal plating, metal foil production, or printed circuit board production.
13. 13. Use of the electrode of claim 12, comprising electrowinning, electrosynthesis, metal plating, metal foil production, or printed circuit board production, for metallic nickel, copper, cobalt, zinc, silver, gold, or manganese.
14. 13. Use of the electrode according to claim 12, wherein the electrode is used as an insoluble anode for electrowinning.
15. 10. A method for manufacturing the electrode of claim 1, comprising: providing an electrode substrate; Optionally, before the step of forming the catalyst layer, a step of forming an intermediate layer on the substrate, wherein the intermediate layer on the substrate is formed by chemical vapor deposition or physical vapor deposition; Optionally, before the step of forming the catalyst layer, a step of forming a catalyst base layer on the substrate or the intermediate layer, the catalyst base layer being formed by a paint pyrolysis method or a plasma spraying method; forming a catalyst layer by paint pyrolysis or plasma spraying.
16. 16. The method of claim 15, wherein the catalyst layer is formed by applying a coating solution containing iridium or a coating solution containing iridium and tantalum to the surface of the substrate or the surface of the intermediate layer, followed by drying and sintering.
17. The method of claim 15, wherein the intermediate layer is formed by magnetron sputtering.