Hydration process for low leakage anode foil

Abstract

The application discloses a hydration treatment method of low-creeping anode foil, and belongs to the technical field of aluminum electrolytic capacitor anode foil. The method adopts the way of grading water boiling and adding low-concentration citric acid to improve the quality of the hydration film, and introduces an ultralow-temperature technology treatment between two-stage water boiling, so that the problem of increased power consumption of products caused by the citric acid water boiling technology can be effectively solved. Compared with the existing mixed acid formation process in the industry, the power consumption is similar, the capacity is 3% lower, and the leakage current is reduced by 50%. The application provides a method which can combine the liquid nitrogen ultralow-temperature technology with the citric acid grading water boiling, so that the leakage current of the anode aluminum foil is lower under the premise of ensuring normal production, and the service life is prolonged.

Description

Technical Field

[0001] This invention relates to the field of aluminum electrolytic capacitor anode foil technology, and more specifically to a hydration treatment method for low leakage current anode foil. Background Technology

[0002] With the development of aluminum electrolytic capacitors, not only is high capacitance required for the anode foil, but its service life is also increasingly demanding, as leakage current is closely related to product lifespan. Traditional formation processes typically involve high-temperature boiling, followed by a boric acid-based or organic acid-based pre-formation, then heat treatment, primary boric acid repair, phosphoric acid depolarization treatment, secondary boric acid repair, heat treatment, tertiary boric acid repair, post-treatment, and drying. The high-temperature boiling process produces a hydrated alumina film, which consists of a dense layer and a porous layer with numerous pores. During subsequent formation processes, the hydrated film gradually dehydrates and crystallizes, causing volume shrinkage and generating numerous pore defects in the middle portion of the oxide film. Furthermore, it easily retains anionic impurities, leading to increased leakage current in the anode foil. Current technologies cannot completely repair these internal defects in the oxide film. The use of dilute solutions of organic acids, inorganic acids and their salts, or alcohol solutions for boiling in water to improve the quality of hydrated films has been reported in relevant industry literature. However, such techniques inevitably hinder the growth of hydrated films, as described by Shen Xingsu and Yan Jixin in their article "Crystallized Composite Anodic Oxide Films of Aluminum: Formation of Anodic Oxide Films in the Presence of Hydrated Oxide Films." The thickness of the hydrated film largely determines the final power consumption of the anode foil product, and adding inhibitors will lead to an increase in power consumption.

[0003] In the prior art, which has the publication number CN112017865A (invention title: a hydration treatment method for reducing leakage current of aluminum foil), sulfuric acid, a mixture of various organic acids, inorganic acids and organic and inorganic salts are added to the aluminum foil during high-temperature boiling to slow down the hydration rate, dissolve the loose layer of the hydration film, improve the overall density of the hydration film, improve the quality of the hydration film, and reduce leakage current.

[0004] However, the method involves adding substances to the boiling water to inhibit the hydration reaction rate and reduce the thickness of the dense hydration film, issues that have been reported in early industry research literature, leading to a significant increase in power consumption. This problem was avoided in the patent.

[0005] In the prior art with publication number CN109859949A (invention title: a method for reducing leakage current of medium and high voltage forming foil), after the aluminum etched foil is boiled in water at high temperature, it is subjected to solution immersion treatment. The solution contains a variety of organic acids and weakly alkaline inorganic salts. Before forming, the loose layer of the hydrated film is dissolved, thereby improving the quality of the hydrated film and reducing the leakage current of the forming foil.

[0006] However, the existing technology, by dissolving the loose layer of the hydrated membrane after boiling in high-temperature water with a solution containing various organic acids and weakly alkaline inorganic salts, has a limited effect on improving product defects compared to the boiling stage which inhibits the growth of the loose layer of the hydrated membrane. Summary of the Invention

[0007] The purpose of this invention is to provide a hydration treatment method for low-leakage anode foil. This method improves the hydration film and reduces leakage current by boiling in citric acid, while simultaneously introducing liquid nitrogen cryogenic treatment technology to address the issue of increased power consumption. The leakage current of the prepared anode foil is reduced by 50% compared to existing mixed acid processes, thereby extending product lifespan. Capacity loss is less than 3%, still meeting market demands.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A hydration treatment method for low-leakage anode foil, employing a five-stage formation process at 520V and 0.842μF / cm. 2 A 530V anode foil is prepared by forming a etched foil of a specified specification; the method includes the following steps:

[0010] (1) One-time high-temperature water boiling treatment: Immerse the etched foil in pure water at 95-100℃ for 1.5-5 min; the conductivity of pure water is less than 5 μs / cm;

[0011] (2) Ultra-low temperature treatment: After pre-drying the foil surface, ultra-low temperature treatment is carried out; the ultra-low temperature treatment temperature is -150 to -196℃, and the ultra-low temperature treatment time is 0.5-1min;

[0012] (3) Secondary high-temperature water boiling treatment: Immerse in citric acid aqueous solution at 90-100℃ for 3-10 minutes;

[0013] (4) The foil, after being boiled twice at high temperatures, undergoes a five-stage chemical formation process;

[0014] (5) First roasting treatment: carried out in a roasting furnace, with a heat treatment temperature of 400-550℃ and a time of 1-1.5min;

[0015] (6) Primary Repair Treatment: The oxide film is repaired using a primary repair solution. The primary repair solution consists of 0.5-1.5 g / L ammonium pentaborate, 35-55 g / L boric acid, and the remainder is water. The treatment time for the primary repair is 5-7 min, the treatment temperature is 75-95℃, and the current density is 80 mA / cm². 2 Voltage 525-535V;

[0016] (7) Intermediate treatment: Intermediate treatment is carried out with a phosphoric acid aqueous solution with a concentration of 60-80 g / L for 3-4.5 min at a temperature of 55-75℃;

[0017] (8) Secondary repair treatment: The oxide film is repaired using a secondary repair solution. The secondary repair solution consists of: ammonium pentaborate 0.5-1.5 g / L, boric acid 35-55 g / L, and the remainder is water. The secondary repair treatment time is 5-7 min, the treatment temperature is 75-95℃, and the current density is 80 mA / cm². 2 Voltage 525-535V;

[0018] (9) Secondary roasting treatment: carried out in a roasting furnace, with a heat treatment temperature of 300-460℃ and a time of 1-1.5min;

[0019] (10) Three-stage repair treatment: The oxide film is repaired using a three-stage repair solution. The composition of the three-stage repair solution is: ammonium pentaborate 0.5-1.5 g / L, boric acid 35-55 g / L, and the remainder is water. The three-stage repair treatment time is 5-7 min, the treatment temperature is 75-95℃, and the current density is 80 mA / cm². 2 Voltage 525-535V;

[0020] (11) Post-treatment: Immerse in an aqueous solution of ammonium dihydrogen phosphate with a concentration of 6-9 g / L for 2-3 min at a treatment temperature of 30-60℃.

[0021] Furthermore, in step (2), the processing temperature of the pre-drying treatment is 70-80℃.

[0022] Further, in step (3), the concentration of the citric acid aqueous solution is 10-50 mg / L.

[0023] Further, in step (4), a primary formation solution is used for primary formation treatment. The primary formation solution consists of: 0.8-1.6 g / L ammonium dihydrogen phosphate, 1.8-2.8 g / L citric acid, 1.5-3 g / L triammonium citrate, and the remainder is water. The primary formation treatment time is 8-12 min, the treatment temperature is 75-95℃, and the current density is 80 mA / cm². 2 The conversion voltage is 115-120V.

[0024] Further, in step (4), a secondary formation solution is used for secondary formation treatment. The composition of the secondary formation solution is: 0.1-1 g / L ammonium dihydrogen phosphate, 1-2 g / L citric acid, 1-2 g / L triammonium citrate, and the remainder is water. The secondary formation treatment time is 7-10 min, the treatment temperature is 75-95℃, and the current density is 80 mA / cm². 2 The conversion voltage is 250-270V.

[0025] Further, in step (4), a three-stage formation solution is used for three-stage formation treatment. The composition of the three-stage formation solution is: ammonium pentaborate 1.5-3.5 g / L, boric acid 35-55 g / L, and the remainder is water. The three-stage formation treatment time is 8 min, the treatment temperature is 75-95℃, and the current density is 80 mA / cm². 2 The voltage is converted to 380-410V.

[0026] Further, in step (4), a four-stage formation solution is used for the four-stage formation treatment. The four-stage formation solution consists of: ammonium pentaborate 1-2 g / L, boric acid 35-55 g / L, and the remainder is water. The four-stage formation treatment time is 8-10 min, the treatment temperature is 75-95℃, and the current density is 80 mA / cm². 2 It is converted to 470-490V.

[0027] Further, in step (4), a five-stage formation solution is used for five-stage formation treatment. The composition of the five-stage formation solution is: ammonium pentaborate 0.5-1.5 g / L, boric acid 35-55 g / L, and the remainder is water. The five-stage formation treatment time is 6-9 min, the treatment temperature is 75-95℃, and the current density is 80 mA / cm². 2 Voltage 525-535V.

[0028] Further, the foil after the post-treatment in step (11) is dried at a temperature of 150-300℃ for 2-3 minutes; after drying, an anode foil with a specification of 530V can be prepared.

[0029] The design principle of this invention is as follows:

[0030] This invention primarily addresses the increased power consumption problem arising from existing technologies for improving hydration films and reducing anode foil leakage current. It creatively introduces a combination of liquid nitrogen cryogenic treatment and citric acid-based graded boiling technology, thereby improving hydration film quality while simultaneously resolving the increased power consumption issue. Existing related patents have all avoided this negative effect.

[0031] During the high-temperature boiling process of aluminum etched foil, the hydration reaction rate decreases sharply as the hydration film grows. The first high-temperature boiling of the aluminum etched foil uses pure water to ensure the thickness of the dense hydration film layer. This is followed by liquid nitrogen cryogenic treatment. With minimal impact on the hydration film composition, the difference in thermal expansion coefficients between the hydration film and the aluminum substrate induces shrinkage cracks, exposing the aluminum substrate. Simultaneously, the partial freezing shrinkage of the hydration film fully exposes internal defects, facilitating sufficient contact between the solution and the aluminum substrate during the second boiling process and significantly increasing the hydration reaction rate. Adding a trace amount of citric acid during the second high-temperature boiling dissolves the loose layer of the hydration film from the first boiling and inhibits its growth during the second boiling. The thickness of the dense hydration film layer, which plays a major role in energy saving, remains largely unchanged under the promoting effect of the liquid nitrogen cryogenic treatment. Reducing the loose layer of the hydration film decreases the crystallinity of the final oxide film. After optimization, the anode foil leakage current is reduced by 50% compared to existing mixed acid processes, while maintaining the same power consumption level and achieving a capacity loss of less than 3.0%.

[0032] The advantages and beneficial effects of this invention are as follows:

[0033] This invention is highly operable and significantly reduces leakage current. By employing liquid nitrogen cryogenic treatment combined with citric acid graded boiling technology, the defect content of the oxide film on the anode foil produced by the formation process is reduced, effectively lowering the product leakage current while minimizing capacity loss. Compared to conventional formation methods (0.036 mA / cm²), this invention achieves a significantly lower leakage current. 2 Compared to the previous method, this method can reduce leakage current by 50% (0.018 mA / cm). 2 ). Attached Figure Description

[0034] Figure 1 The results of 24-hour leakage current detection of the anode foils prepared in Examples 1-4 and Comparative Example 1 are shown. Detailed Implementation

[0035] To further understand the present invention, the present invention is described below with reference to examples. However, the examples are only for further illustrating the features and advantages of the present invention, and are not intended to limit the scope of the claims of the present invention.

[0036] To address the leakage current reduction problem in existing technologies, this invention provides a formation method combining liquid nitrogen cryogenic treatment with citric acid boiling, which offers the advantage of low leakage current. The method involves adding a liquid nitrogen cryogenic treatment step after a first high-temperature boiling step. The first high-temperature boiling uses pure water, while a trace amount of citric acid is added during the second high-temperature boiling step. The overall scheme is a combination of liquid nitrogen cryogenic treatment, a citric acid-based graded boiling step, and a five-stage formation process.

[0037] The key technical point of this invention is that the liquid nitrogen cryogenic treatment, without significantly affecting the composition of the hydrated film, utilizes the difference in thermal expansion coefficients between the hydrated film and the aluminum substrate to generate shrinkage cracks. Simultaneously, the partial freezing shrinkage of the hydrated film fully exposes internal defects, facilitating thorough contact between the solution and the aluminum substrate during the secondary boiling process and significantly increasing the hydration reaction rate. Adding a trace amount of citric acid during the secondary high-temperature boiling dissolves the loose layer of the hydrated film from the first boiling and inhibits the growth of the loose layer during the secondary boiling. The thickness of the dense hydrated film layer, which plays a major role in energy saving during boiling, remains largely unchanged under the combined effects of tiered boiling to maximize hydration reaction efficiency and the promoting effect of the liquid nitrogen cryogenic treatment.

[0038] Example 1:

[0039] This embodiment uses a five-stage formation method, employing 520V and 0.842μF / cm. 2 The etched foil of a certain specification is subjected to formation to prepare a 530V specification anode foil. The specific process is as follows:

[0040] 1. One-time high-temperature water boiling treatment: Immerse in pure water at 98℃ (conductivity less than 5μs / cm) for 3 minutes.

[0041] 2. Pre-drying treatment: The foil surface is dried at a temperature of 80℃.

[0042] 3. Ultra-low temperature treatment: The treatment temperature is -196℃ and the treatment time is 0.5min.

[0043] 4. Secondary high-temperature water boiling treatment: Immerse in citric acid aqueous solution (10mg / L) at 98℃ for 3 minutes.

[0044] 5. Primary Formation: Anodizing is performed using a primary formation solution. The primary formation solution consists of: 0.7 g / L ammonium dihydrogen phosphate, 2.2 g / L citric acid, 1.8 g / L triammonium citrate, and the remainder being water. The treatment time is 7 minutes, the treatment temperature is 90℃, and the current density is 80 mA / cm². 2 Voltage 120V.

[0045] 6. Secondary Formation: Anodizing is performed using a secondary formation solution. The secondary formation solution consists of: 0.5 g / L ammonium dihydrogen phosphate, 1 g / L citric acid, 1 g / L triammonium citrate, and the remainder is water. The treatment time is 10 min, the treatment temperature is 90℃, and the current density is 80 mA / cm². 2 Voltage 270V.

[0046] 7. Three-stage formation: Anodizing is performed using a three-stage formation solution. The composition of the three-stage formation solution is: ammonium pentaborate 2.4 g / L, boric acid 45 g / L, and the remainder is water. The treatment time is 7 min, the treatment temperature is 90℃, and the current density is 80 mA / cm².2 Voltage 400V.

[0047] 8. Four-stage formation: Anodizing is performed using a four-stage formation solution. The four-stage formation solution consists of: 1.6 g / L ammonium pentaborate, 45 g / L boric acid, and the remainder is water. The treatment time is 7 min, the treatment temperature is 90℃, and the current density is 80 mA / cm². 2 Voltage 490V.

[0048] 9. Five-stage formation: Anodizing is performed using a five-stage formation solution. The five-stage formation solution consists of: 1 g / L ammonium pentaborate, 45 g / L boric acid, and the remainder is water. The treatment time is 9 minutes, the treatment temperature is 90℃, and the current density is 80 mA / cm². 2 Voltage 530V.

[0049] 10. First firing: heat treatment temperature 480℃, time 1.5min.

[0050] 11. Single-stage repair treatment: The oxide film is repaired using a 1 g / L ammonium pentaborate and 45 g / L boric acid repair solution. The treatment time is 7 minutes, the temperature is 90℃, and the current density is 80 mA / cm². 2 Voltage 530V.

[0051] 12. Intermediate treatment: 65 g / L phosphoric acid aqueous solution, treatment time 4.5 min, temperature 65℃.

[0052] 13. Secondary Repair Treatment: The oxide film is repaired using a 1 g / L ammonium pentaborate and 45 g / L boric acid repair solution. The treatment time is 7 minutes, the temperature is 90℃, and the current density is 80 mA / cm². 2 Voltage 530V.

[0053] 14. Secondary calcination: Heat treatment temperature 380℃, time 1.5min.

[0054] 15. Three-stage repair treatment: The oxide film is repaired using a 1 g / L ammonium pentaborate and 45 g / L boric acid repair solution. The treatment time is 7 minutes, the temperature is 90℃, and the current density is 80 mA / cm². 2 Voltage 530V.

[0055] 16. Post-treatment: Immerse in a 6.5 g / L ammonium dihydrogen phosphate aqueous solution for 2 min at a treatment temperature of 35℃.

[0056] 17. Drying: Drying temperature 260℃, processing time 2min.

[0057] The above steps can be used to prepare an anode foil with a specification of 530V.

[0058] Anodizing at a formation voltage of 530V resulted in a foil capacitance of 0.860 μF / cm². 2 Withstand voltage is 533V, power consumption is 4.975w·h / cm³. 2 The 24-hour leakage current is 0.028 mA / cm². 2 .

[0059] Example 2: The method is the same as in Example 1, except for a second high-temperature boiling treatment: immersion in a citric acid (10 mg / L) aqueous solution at 98°C for 5 minutes. Using Example 2, the foil capacitance is 0.855 μF / cm². 2 Withstand voltage is 531V, power consumption is 4.555w·h / cm³. 2 The 24-hour leakage current is 0.027 mA / cm². 2 .

[0060] Example 3: The method is the same as in Example 1, except for a second high-temperature water boiling treatment: immersion in a citric acid (50 mg / L) aqueous solution at 98°C for 3 minutes. Using Example 3, the foil capacitance is 0.854 μF / cm². 2 Withstand voltage is 532V, power consumption is 5.508w·h / cm³. 2 The 24-hour leakage current is 0.021 mA / cm². 2 .

[0061] Example 4: The method is the same as in Example 1, except for a second high-temperature water boiling treatment: immersion in a citric acid (50 mg / L) aqueous solution at 98°C for 5 minutes. Using Example 4, the foil capacitance is 0.845 μF / cm². 2 Withstand voltage is 532V, and power consumption is 5.021w·h / cm³. 2 The 24-hour leakage current is 0.018 mA / cm². 2 .

[0062] Comparative Example 1: The method was the same as in Example 1, except that before primary formation, only a high-temperature water boiling treatment was performed: immersion in pure water at above 98°C for 10 minutes. Using Comparative Example 1, the foil capacitance was 0.871 μF / cm². 2 Withstand voltage is 532V, power consumption is 5.008w·h / cm³. 2 The 24-hour leakage current is 0.036 mA / cm². 2 .

[0063] Table 1 shows the performance parameters of the anode foils prepared in Examples 1-4 and Comparative Example 1.

[0064] Figure 1 The results of 24-hour leakage current detection of the anode foils prepared in Examples 1-4 and Comparative Example 1 are shown.

[0065] Table 1: Performance parameters of the anode foils prepared in the examples and comparative examples.

[0066]

[0067]

[0068] According to Examples 1-4 and Comparative Example 1, it can be seen that:

[0069] Increasing the concentration of citric acid during boiling has a greater effect on reducing leakage current than increasing the boiling time; both methods reduce leakage current. Increasing both citric acid concentration and boiling time reduce capacity, with similar effects on capacity under the conditions of the listed examples. Increasing the concentration of citric acid during boiling increases power consumption, while increasing the boiling time decreases power consumption; with similar effects on power consumption under the conditions of the listed examples. Considering the performance of the anode foil prepared under the above-mentioned example conditions, including capacity, power consumption, and leakage current, Example 4 is the preferred option. Compared to the comparative sample in Comparative Example 1, the leakage current decreased significantly after 24 hours, from 0.036 mA / cm². 2 It decreased to 0.018 mA / cm 2 The hydration and power consumption are similar over 1 hour, but the capacity is slightly reduced.

Claims

1. A hydration treatment method for a low-leakage anode foil, characterized in that: This method employs a five-stage formation process, using 520V and 0.842μF / cm. 2 A 530V anode foil is prepared by forming a etched foil of a specified specification; the method includes the following steps: (1) One-time high-temperature water boiling treatment: Immerse the etched foil in pure water at 95-100℃ for 1.5-5 min; the conductivity of pure water is less than 5 μs / cm; (2) Ultra-low temperature treatment: After pre-drying the foil surface, ultra-low temperature treatment is carried out; the ultra-low temperature treatment temperature is -150 to -196℃, and the ultra-low temperature treatment time is 0.5-1min; (3) Secondary high-temperature water boiling treatment: Immerse in a citric acid aqueous solution at 90-100℃ for 3-10 minutes; the concentration of the citric acid aqueous solution is 10-50 mg / L; (4) The foil, after being boiled twice at high temperatures, undergoes a five-stage chemical formation process; (5) First roasting treatment: carried out in a roasting furnace, with a heat treatment temperature of 400-550℃ and a time of 1-1.5min; (6) Primary repair treatment: The oxide film is repaired using a primary repair solution. The primary repair solution consists of 0.5-1.5 g / L ammonium pentaborate, 35-55 g / L boric acid, and the remainder is water. The treatment time for the primary repair is 5-7 min, the treatment temperature is 75-95℃, and the current density is 80 mA / cm². 2 Voltage 525-535V; (7) Intermediate treatment: Intermediate treatment is carried out using a phosphoric acid aqueous solution with a concentration of 60-80 g / L for 3-4.5 min at a temperature of 55-75℃; (8) Secondary repair treatment: The oxide film is repaired using a secondary repair solution. The composition of the secondary repair solution is: ammonium pentaborate 0.5-1.5 g / L, boric acid 35-55 g / L, and the remainder is water. The secondary repair treatment time is 5-7 min, the treatment temperature is 75-95℃, and the current density is 80 mA / cm. 2 Voltage 525-535V; (9) Secondary roasting treatment: carried out in a roasting furnace, with a heat treatment temperature of 300-460℃ and a time of 1-1.5min; (10) Three-stage repair treatment: The oxide film is repaired using a three-stage repair solution. The composition of the three-stage repair solution is: ammonium pentaborate 0.5-1.5 g / L, boric acid 35-55 g / L, and the remainder is water. The three-stage repair treatment time is 5-7 min, the treatment temperature is 75-95℃, and the current density is 80 mA / cm. 2 Voltage 525-535V; (11) Post-treatment: Immerse in an aqueous solution of ammonium dihydrogen phosphate with a concentration of 6-9 g / L for 2-3 min at a treatment temperature of 30-60℃.

2. The hydration treatment method for low leakage current anode foil according to claim 1, characterized in that: In step (2), the pre-drying treatment temperature is 70-80℃.

3. The hydration treatment method for low leakage current anode foil according to claim 1, characterized in that: In step (4), a primary formation solution is used for primary formation treatment. The primary formation solution consists of: 0.8-1.6 g / L ammonium dihydrogen phosphate, 1.8-2.8 g / L citric acid, 1.5-3 g / L triammonium citrate, and the remainder is water. The primary formation treatment time is 8-12 min, the treatment temperature is 75-95℃, and the current density is 80 mA / cm². 2 The conversion voltage is 115-120V.

4. The hydration treatment method for low leakage current anode foil according to claim 1 or 3, characterized in that: In step (4), a secondary formation solution is used for secondary formation treatment. The composition of the secondary formation solution is: 0.1-1 g / L ammonium dihydrogen phosphate, 1-2 g / L citric acid, 1-2 g / L triammonium citrate, and the remainder is water. The secondary formation treatment time is 7-10 min, the treatment temperature is 75-95℃, and the current density is 80 mA / cm². 2 The conversion voltage is 250-270V.

5. The hydration treatment method for low leakage current anode foil according to claim 1, characterized in that: In step (4), a three-stage formation solution is used for three-stage formation treatment. The composition of the three-stage formation solution is: ammonium pentaborate 1.5-3.5 g / L, boric acid 35-55 g / L, and the remainder is water. The three-stage formation treatment time is 8 min, the treatment temperature is 75-95℃, and the current density is 80 mA / cm². 2 The conversion voltage is 380-410V.

6. The hydration treatment method for low leakage current anode foil according to claim 1, characterized in that: In step (4), a four-stage formation solution is used for the four-stage formation treatment. The four-stage formation solution consists of: ammonium pentaborate 1-2 g / L, boric acid 35-55 g / L, and the remainder is water. The four-stage formation treatment time is 8-10 min, the treatment temperature is 75-95℃, and the current density is 80 mA / cm². 2 It is converted to 470-490V.

7. The hydration treatment method for low leakage current anode foil according to claim 1, characterized in that: In step (4), a five-stage formation process is performed using a five-stage formation solution. The five-stage formation solution consists of: 0.5-1.5 g / L ammonium pentaborate, 35-55 g / L boric acid, and the remainder is water. The five-stage formation process takes 6-9 minutes, is performed at a temperature of 75-95℃, and uses a current density of 80 mA / cm². 2 Voltage 525-535V.

8. The hydration treatment method for low leakage current anode foil according to claim 1, characterized in that: The foil after step (11) is dried at a temperature of 150-300℃ for 2-3 minutes. After drying, an anode foil with a specification of 530V can be prepared.

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