A conductive solution and its application in anodizing of aluminum foil

Abstract

The present invention discloses a conductive solution and its application in the anodic oxidation of aluminum foils. The conductive solution comprises an electricity supply agent, an additive and water. Among them, the electricity supply agent is at least one of ammonium phosphate, ammonium dihydrogen phosphate and diammonium hydrogen phosphate; the additive is R'-PO4, where R' is an active metal ion; by mass percentage, the content of the electricity supply agent in the conductive solution is 1.5 - 10 wt%, the content of the additive is 0.01 - 0.10 wt%, and the rest is water. The conductive solution of the present invention contains a large amount of -NH4, -H2PO4, -HPO4. Within a suitable pH value range, its conductivity is stronger and more balanced; compared with the phosphoric acid conductive solution, the applicable range is expanded, and it is applicable to the conductive solution feeding occasions of all process systems for the anodic oxidation of the electrodes of aluminum electrolytic capacitors, and is applicable to the medium-high voltage and ultra-high voltage forming production of etched aluminum foils and sintered aluminum foils.

Description

Technical Field

[0001] The present invention belongs to the field of manufacturing anode materials for aluminum electrolytic capacitors, and particularly relates to a conductive solution and its application in anodic oxidation of aluminum foils. Background Art

[0002] The formation of aluminum foils is a key process in manufacturing anode foils. The formation of aluminum foils utilizes the electrochemical principle to anodize the aluminum foils, enabling oxygen atoms in the formation solution to combine with aluminum atoms, thereby forming a dielectric layer of an oxide film with specific voltage resistance on the surface of the aluminum foils. The quality of this oxide film dielectric layer is directly related to the performance of aluminum electrolytic capacitors. With the trend of miniaturization of electrical products and the increasing energy shortage, higher requirements are put forward for the formation efficiency of aluminum foils.

[0003] Currently, the common method for forming aluminum foils is to supply power by combining a metal conductive roller and liquid conduction. Among them, the liquid conduction power supply technology connects the positive electrode of the formation DC power supply to the anode plate in the liquid feeding tank and the negative electrode of the formation DC power supply to the cathode plate in the formation tank. When the aluminum foil passes through the formation tank and the liquid feeding tank, the conductive aluminum foil forms a closed loop between the positive and negative electrodes of the formation DC power supply, and the formation liquid applies electrical energy to the aluminum foil, thereby completing the anodic oxidation process of the aluminum foil.

[0004] According to the different properties of formation solutions, the existing formation processes for anode foils mainly include three categories: pure boric acid formation process, organic acid formation process, and mixed acid formation process. In the existing formation processes, ammonium adipate or citric acid and its salts are often used as power supply agents. However, the service life of the ammonium adipate conductive solution is relatively short. After long-term use, it is prone to turbidity and scale formation, which easily causes creases and fractures in the aluminum foil. In severe cases, it will cause foil breakage and interrupt production. After citric acid and its salts are used for a period of time, they are also prone to form gel-like substances, making it difficult to recycle. At the same time, generally, the liquid power supply tank is located downstream of the formation production line, and a relatively dense oxide film has formed on the aluminum foil upstream of the liquid power supply tank, resulting in increased difficulty in power supply. During the production process, phenomena such as aluminum foil curling and floating wrinkles frequently occur, leading to a high incidence of foil breakage accidents. Therefore, it is urgent to develop a new power supply agent. To solve this problem, the Chinese invention patent with the publication number CN109056024B discloses an organic acid formation process for producing high specific capacitance electrode foils. The electrolyte used in this process consists of a power supply agent, an additive, and water. Among them, the power supply agent is phosphoric acid, and its concentration is 20 - 60 g / L; the additive is R’-H2PO4 or R’-HPO4, where R’ is an active metal ion (such as potassium, sodium, calcium, or magnesium), and its concentration is 0.1 - 1.0 g / L. This conductive solution uses phosphoric acid to replace adipic acid or citric acid and its salts as the power supply agent, which only solves the problems of aluminum foil curling and floating wrinkles in organic acid formation; however, phosphoric acid as a power supply agent is difficult to solve the problems of aluminum foil curling and floating wrinkles in pure boric acid or mixed acid formation, and its applicable range is relatively small. Summary of the Invention

[0005] The object of the present invention is to provide a conductive solution and its application in the anodic oxidation of aluminum foil to solve the problems of aluminum foil curling and floating wrinkles in the aluminum foil formation process (including inorganic acid formation process, organic acid formation process, and mixed acid formation process).

[0006] To achieve the above-mentioned invention object, the technical solution of the present invention includes:

[0007] A conductive solution, comprising a power supply agent, an additive, and water. The power supply agent is at least one of ammonium phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate;

[0008] The additive is R’-PO4, where R’ is an active metal ion;

[0009] By mass percentage, the content of the power supply agent in the conductive solution is 1.5 - 10 wt%, the content of the additive is 0.01 - 0.1 wt%, and the rest is water.

[0010] The present invention uses at least one of ammonium phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate as the power supply agent, and uses R'-PO4 as the additive. Compared with the conductive solution using phosphoric acid as the power supply agent and using R'-H2PO4 or R'-HPO4 as the additive, this conductive solution has the following advantages: due to the large amount of -NH4, -H2PO4, and -HPO4, within a suitable pH value range, its conductivity is stronger and more balanced. Therefore, the conductive solution of the present invention can be applied to the power supply occasions of conductive solutions in all process systems for anodic oxidation of aluminum electrolytic capacitor electrode foils, and is applicable to the medium-high voltage and ultra-high voltage formation production of etched aluminum foils and sintered aluminum foils.

[0011] Preferably, in the above-mentioned conductive solution, the additive is at least one of sodium phosphate and potassium phosphate.

[0012] Preferably, in the above-mentioned conductive solution, the water is pure water with a resistivity of not less than 2 ΜΩ·cm to ensure that no other impurity ions have an impact.

[0013] Preferably, in the above-mentioned conductive solution, the conductivity is 15 to 100 ms / cm and the pH value is 7.0 to 9.0.

[0014] When at least two of ammonium phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate are used as the power supply agent, the present invention does not have excessive requirements for the mass ratio between these two or three, as long as the total dosage reaches the above-mentioned mass percentage and the target conductivity and pH value can be obtained.

[0015] Similarly, when a combination of sodium phosphate and potassium phosphate is used as the additive, the present invention also does not have excessive requirements for the ratio between these two additives, as long as the total dosage reaches the above-mentioned mass percentage.

[0016] The present invention also provides the application of the above-mentioned conductive solution in anodic oxidation of aluminum foil.

[0017] In the present invention, the anodic oxidation of the aluminum foil can be carried out by an inorganic acid formation process, an organic acid formation process, or a mixed acid formation process.

[0018] Preferably, the application of the above-mentioned conductive solution in anodic oxidation of aluminum foil includes the following steps:

[0019] (1) Prepare a conductive solution with a conductivity of 15 to 100 ms / cm and a pH value of 7.0 to 9.0 by mixing the power supply agent, additive, and water according to a preset mass percentage;

[0020] (2) Place the conductive solution in a liquid power supply tank to apply electric energy to the aluminum foil passing through the liquid power supply tank.

[0021] Preferably, in the step (2), the liquid temperature of the conductive solution is controlled at 10 - 50°C.

[0022] When different formation processes are adopted, the dosages of the power supply agent and the additive in the conductive solution will vary slightly. Specifically, in the organic acid formation process, by mass percentage, the content of the power supply agent in the conductive solution is 9.0 - 10 wt%, and the content of the additive is 0.01 - 0.02 wt%.

[0023] In the mixed acid formation process, by mass percentage, the content of the power supply agent in the conductive solution is 6.0 - 9.0 wt%, and the content of the additive is 0.02 - 0.05 wt%.

[0024] In the inorganic acid formation process, by mass percentage, the content of the power supply agent in the conductive solution is 1.5 - 5.0 wt%, and the content of the additive is 0.05 - 0.1 wt%.

[0025] The present invention also provides an aluminum foil formation production line, which includes a liquid power supply tank, and the conductive solution of the present invention is used in the liquid power supply tank.

[0026] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0027] (1) The present invention uses at least one of ammonium phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate as the power supply agent, and R'-PO4 as the additive. Compared with the conductive solution using phosphoric acid as the power supply agent and R'-H2PO4 or R'-HPO4 as the additive, this conductive solution has the following advantages: due to the large presence of -NH4, -H2PO4, and -HPO4, within a suitable pH value range, its conductivity is stronger and more balanced; compared with the phosphoric acid conductive solution, the applicable range is expanded, and it is applicable to the conductive solution feeding occasions of all process systems for anodic oxidation of the electrodes of aluminum electrolytic capacitors, and is applicable to the medium-high voltage and ultra-high voltage formation production of etched aluminum foil and sintered aluminum foil.

[0028] (2) The conductive solution of the present invention can effectively eliminate the problems that the ammonium adipate conductive solution is prone to turbidity and scale formation, resulting in crease crushing and cracking; it can effectively eliminate the problem that the conductive solution of citric acid and its salts is prone to form gel-like substances after being used for a period of time, making it difficult to recycle. Specific Embodiments

[0029] The technical solutions of the present invention will be further described in detail below by using specific embodiments.

[0030] Example 1 200VF Organic Acid Formation

[0031] A conductive solution, by mass percentage, includes 10.0 wt% of an electricity donor and 0.01 wt% of an additive, with the balance being pure water having a resistivity of 2 ΜΩ·cm;

[0032] Among them, the electricity donor is composed of ammonium phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate, and the mass ratio of ammonium phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate is 8:1:1;

[0033] The additive is composed of sodium phosphate and potassium phosphate, and the mass ratio of sodium phosphate and potassium phosphate is 1:1.

[0034] Using the above conductive solution for the organic acid formation process of aluminum foil, this process includes:

[0035] (1) Compound the above electricity donor, additive, and water into a conductive solution with a conductivity of 100 ms / cm and a pH value of 9.0;

[0036] (2) Control the liquid temperature of the conductive solution at 20 °C, and pass the etched aluminum foil or sintered aluminum foil from the previous formation through the conductive solution to apply electrical energy to the aluminum foil.

[0037] The conductive solution of this example showed no turbidity or scaling after 100 days of use, and no gel-like substances were produced. The product appearance was qualified; and the produced aluminum foils had no curled edges or floating wrinkles, and the quality was good.

[0038] Example 2 200VF Organic Acid Formation

[0039] A conductive solution, by mass percentage, includes 9.0 wt% of an electricity donor and 0.01 wt% of an additive, with the balance being pure water having a resistivity of 2 ΜΩ·cm;

[0040] Among them, the electricity donor is composed of ammonium phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate, and the mass ratio of ammonium phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate is 8:1:1;

[0041] The additive is composed of sodium phosphate and potassium phosphate, and the mass ratio of sodium phosphate and potassium phosphate is 1:1.

[0042] Using the above conductive solution for the organic acid formation process of aluminum foil, this process includes:

[0043] (1) Compound the above electricity donor, additive, and water into a conductive solution with a conductivity of 90 ms / cm and a pH value of 8.5;

[0044] (2) Control the liquid temperature of the conductive solution at 10 °C, and pass the etched aluminum foil or sintered aluminum foil from the previous formation through the conductive solution to apply electrical energy to the aluminum foil.

[0045] After 100 days of use, the conductive solution in this example showed no turbidity or scaling, and no gel-like substances were produced. The appearance of the product was qualified. Moreover, the produced aluminum foils had no curled edges or floating wrinkles and were of good quality.

[0046] Example 3: 365VF mixed-acid formation

[0047] A conductive solution, by mass percentage, includes 9.0 wt% of an electroconductive agent and 0.02 wt% of an additive, with the balance being pure water having a resistivity of 2 ΜΩ·cm.

[0048] Among them, the electroconductive agent is composed of ammonium phosphate and ammonium dihydrogen phosphate, and the mass ratio of ammonium phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate is 8:2.

[0049] The additive is sodium phosphate.

[0050] Using the above conductive solution for the aluminum foil mixed-acid formation process, this process includes:

[0051] (1) Compound the above electroconductive agent, additive, and water into a conductive solution with a conductivity of 90 ms / cm and a pH value of 8.5.

[0052] (2) Control the liquid temperature of the conductive solution at 20°C, and pass the etched aluminum foil or sintered aluminum foil from the previous formation through the conductive solution so as to apply electric energy to the aluminum foil.

[0053] After 100 days of use, the conductive solution in this example showed no turbidity or scaling, and no gel-like substances were produced. The appearance of the product was qualified. Moreover, the produced aluminum foils had no curled edges or floating wrinkles and were of good quality.

[0054] Example 4: 365VF mixed-acid formation

[0055] A conductive solution, by mass percentage, includes 8.0 wt% of an electroconductive agent and 0.02 wt% of an additive, with the balance being pure water having a resistivity of 2 ΜΩ·cm.

[0056] Among them, the electroconductive agent is composed of ammonium phosphate and ammonium dihydrogen phosphate, and the mass ratio of ammonium phosphate and ammonium dihydrogen phosphate is 7.5:2.5.

[0057] The additive is sodium phosphate.

[0058] Using the above conductive solution for the aluminum foil mixed-acid formation process, this process includes:

[0059] (1) Compound the above electroconductive agent, additive, and water into a conductive solution with a conductivity of 80 ms / cm and a pH value of 8.0.

[0060] (2) Control the liquid temperature of the conductive solution at 30°C, and pass the etched aluminum foil or sintered aluminum foil from the previous stage through the conductive solution to apply electrical energy to the aluminum foil.

[0061] After 100 days of use, the conductive solution in this example showed no turbidity or scaling, and no gel-like substances were produced. The appearance of the product was qualified; moreover, the produced aluminum foils had no curled edges or floating wrinkles, and the quality was good.

[0062] Example 5 530VF Mixed Acid Formation

[0063] A conductive solution, by mass percentage, includes 7.0 wt% of an electricity-supplying agent and 0.05 wt% of an additive, with the balance being pure water having a resistivity of 2 ΜΩ·cm;

[0064] Among them, the electricity-supplying agent is ammonium phosphate;

[0065] The additive is sodium phosphate.

[0066] Using the above conductive solution for the aluminum foil mixed acid formation process, this process includes:

[0067] (1) Compound the above electricity-supplying agent, additive, and water into a conductive solution with a conductivity of 70 ms / cm and a pH value of 8.5;

[0068] (2) Control the liquid temperature of the conductive solution at 20°C, and pass the etched aluminum foil or sintered aluminum foil from the previous stage through the conductive solution to apply electrical energy to the aluminum foil.

[0069] After 100 days of use, the conductive solution in this example showed no turbidity or scaling, and no gel-like substances were produced. The appearance of the product was qualified; moreover, the produced aluminum foils had no curled edges or floating wrinkles, and the quality was good.

[0070] Example 6 530VF Mixed Acid Formation

[0071] A conductive solution, by mass percentage, includes 6.0 wt% of an electricity-supplying agent and 0.05 wt% of an additive, with the balance being pure water having a resistivity of 2 ΜΩ·cm;

[0072] Among them, the electricity-supplying agent is ammonium phosphate;

[0073] The additive is potassium phosphate.

[0074] Using the above conductive solution for the aluminum foil mixed acid formation process, this process includes:

[0075] (1) Compound the above electricity-supplying agent, additive, and water into a conductive solution with a conductivity of 70 ms / cm and a pH value of 7.0;

[0076] (2) Control the liquid temperature of the conductive solution at 40 °C, and pass the etched aluminum foil or sintered aluminum foil from the previous forming stage through the conductive solution to apply electrical energy to the aluminum foil.

[0077] After 100 days of use, the conductive solution in this example showed no turbidity or scaling, and no gel-like substances were produced. The appearance of the product was qualified; moreover, the produced aluminum foils had no curled edges or floating wrinkles, and the quality was good.

[0078] Example 7 580VF Inorganic Acid Forming

[0079] A conductive solution, by mass percentage, includes 5.0 wt% of an electricity supply agent and 0.06 wt% of an additive, with the balance being pure water having a resistivity of 2 ΜΩ·cm;

[0080] Among them, the electricity supply agent is composed of ammonium dihydrogen phosphate and diammonium hydrogen phosphate, and the mass ratio of ammonium dihydrogen phosphate to diammonium hydrogen phosphate is 5:5.

[0081] The additive is composed of sodium phosphate and potassium phosphate, and the mass ratio of sodium phosphate to potassium phosphate is 1:1.

[0082] Using the above conductive solution for the aluminum foil inorganic acid forming process, the process includes:

[0083] (1) Compound the above electricity supply agent, additive, and water into a conductive solution with a conductivity of 50 ms / cm and a pH value of 8.0;

[0084] (2) Control the liquid temperature of the conductive solution at 50 °C, and pass the etched aluminum foil or sintered aluminum foil from the previous forming stage through the conductive solution to apply electrical energy to the aluminum foil.

[0085] After 100 days of use, the conductive solution in this example showed no turbidity or scaling, and no gel-like substances were produced. The appearance of the product was qualified; moreover, the produced aluminum foils had no curled edges or floating wrinkles, and the quality was good.

[0086] Example 8 580VF Inorganic Acid Forming

[0087] A conductive solution, by mass percentage, includes 4.0 wt% of an electricity supply agent and 0.06 wt% of an additive, with the balance being pure water having a resistivity of 2 ΜΩ·cm;

[0088] Among them, the electricity supply agent is composed of ammonium dihydrogen phosphate and diammonium hydrogen phosphate, and the mass ratio of ammonium dihydrogen phosphate to diammonium hydrogen phosphate is 9:1.

[0089] The additive is composed of sodium phosphate and potassium phosphate, and the mass ratio of sodium phosphate to potassium phosphate is 1:1.

[0090] Using the above conductive solution for the aluminum foil inorganic acid forming process, the process includes:

[0091] (1) Compound the above power supply agent, additive and water into a conductive solution with a conductivity of 40 ms / cm and a pH value of 7.0;

[0092] (2) Control the liquid temperature of the conductive solution at 20 °C, and pass the pre-stage formed etched aluminum foil or sintered aluminum foil through the conductive solution to apply electric energy to the aluminum foil.

[0093] After 100 days of use, the conductive solution of this example shows no turbidity or scaling, and no gel-like substances are produced. The appearance of the product is qualified; and the produced aluminum foils have no curled edges or floating wrinkles, and the quality is good.

[0094] Example 9 900VF Inorganic Acid Formation

[0095] A conductive solution, by mass percentage, includes 3.0 wt% of a power supply agent and 0.1 wt% of an additive, and the balance is pure water with a resistivity of 2 ΜΩ·cm;

[0096] Among them, the power supply agent is composed of ammonium dihydrogen phosphate and diammonium hydrogen phosphate, and the mass ratio of ammonium dihydrogen phosphate to diammonium hydrogen phosphate is 2:8.

[0097] The additive is sodium phosphate.

[0098] Adopt the above conductive solution for the inorganic acid formation process of aluminum foil. This process includes:

[0099] (1) Compound the above power supply agent, additive and water into a conductive solution with a conductivity of 30 ms / cm and a pH value of 8.0;

[0100] (2) Control the liquid temperature of the conductive solution at 20 °C, and pass the pre-stage formed etched aluminum foil or sintered aluminum foil through the conductive solution to apply electric energy to the aluminum foil.

[0101] After 100 days of use, the conductive solution of this example shows no turbidity or scaling, and no gel-like substances are produced. The appearance of the product is qualified; and the produced aluminum foils have no curled edges or floating wrinkles, and the quality is good.

[0102] Example 10 900VF Inorganic Acid Formation

[0103] A conductive solution, by mass percentage, includes 1.5 wt% of a power supply agent and 0.1 wt% of an additive, and the balance is pure water with a resistivity of 2 ΜΩ·cm;

[0104] Among them, the power supply agent is composed of ammonium dihydrogen phosphate and diammonium hydrogen phosphate, and the mass ratio of ammonium dihydrogen phosphate to diammonium hydrogen phosphate is 9:1.

[0105] The additive is sodium phosphate.

[0106] The above conductive solution is used in the process of inorganic acidification of aluminum foil, and the process includes:

[0107] (1) Compound the above power supply agent, additive and water into a conductive solution with a conductivity of 15 ms / cm and a pH value of 7.0;

[0108] (2) Control the liquid temperature of the conductive solution at 40°C, and pass the etched aluminum foil or sintered aluminum foil of the previous stage through the conductive solution so as to apply electric energy to the aluminum foil.

[0109] After 100 days of use, the conductive solution of this embodiment shows no turbidity or scaling, and no gel-like substances are produced. The appearance of the product is qualified; and the produced aluminum foils have no curled edges or floating wrinkles, and the quality is good.

[0110] Comparative Example 1

[0111] The same process as in Example 6 is used for 530 VF mixed acidification, but the electrolyte solution disclosed in the Chinese invention patent with the publication number CN109056024B is used as the conductive solution.

[0112] After 100 days of use, the conductive solution of this comparative example shows no turbidity or scaling, and no gel-like substances are produced. The appearance of the product is qualified; but the produced aluminum foils still have curled edges and floating wrinkles.

[0113] Comparative Example 2

[0114] The same process as in Example 9 is used for 900 VF inorganic acidification, but the electrolyte solution disclosed in the Chinese invention patent with the publication number CN109056024B is used as the conductive solution.

[0115] After 100 days of use, the conductive solution of this comparative example shows no turbidity or scaling, and no gel-like substances are produced. The appearance of the product is qualified; but the produced aluminum foils still have curled edges and floating wrinkles.

[0116] As described above, it is only the preferred embodiment of the embodiments of the present invention, and does not impose any form of limitation on the implementation of the present invention. Any modification, equivalent change and modification made according to the technical essence of the embodiments of the present invention still belong to the scope of the technical solutions of the embodiments of the present invention.

Claims

1. Application of conductive solution in anodic oxidation of aluminum foil, characterized in that the conductive solution comprises an electricity supply agent, an additive and water; the electricity supply agent is at least one of ammonium phosphate, ammonium dihydrogen phosphate and diammonium hydrogen phosphate; the additive is R'-PO4, where R' is an active metal ion; by mass percentage, the content of the electricity supply agent in the conductive solution is 1.5-10 wt%, the content of the additive is 0.01-0.10 wt%, and the rest is water; the application comprises the following steps: (1) Prepare a conductive solution with a conductivity of 15-100 ms / cm and a pH value of 7.0-9.0 by mixing an electricity supply agent, an additive and water according to a preset mass percentage; (2) Place the conductive solution in a liquid power supply tank to apply electric energy to the aluminum foil passing through the liquid power supply tank.

2. The application of the conductive solution according to claim 1 in the anodization of aluminum foil, characterized in that, The additive is at least one of sodium phosphate and potassium phosphate.

3. The application of the conductive solution as described in claim 1 in the anodization of aluminum foil, characterized in that, The water is pure water with a resistivity of not less than 2 ΜΩ·cm.

4. The application of the conductive solution as described in claim 1 in the anodization of aluminum foil, characterized in that, The anodic oxidation of the aluminum foil is carried out by an inorganic acidification process, an organic acidification process or a mixed acidification process.

5. The application of the conductive solution according to claim 1 in the anodization of aluminum foil, characterized in that, In step (2), the liquid temperature of the conductive solution is controlled at 10-50°C.

6. The application of the conductive solution according to claim 1 in the anodization of aluminum foil, characterized in that, In the organic acidification process, by mass percentage, the content of the electricity supply agent in the conductive solution is 9.0-10 wt%, and the content of the additive is 0.01-0.02 wt%; In the mixed acidification process, by mass percentage, the content of the electricity supply agent in the conductive solution is 6.0-9.0 wt%, and the content of the additive is 0.02-0.05 wt%; In the inorganic acidification process, by mass percentage, the content of the electricity supply agent in the conductive solution is 1.5-5.0 wt%, and the content of the additive is 0.05-0.1 wt%.

7. An aluminum foil forming production line, comprising a liquid feed tank, characterized in that: The conductive solution used in the liquid power supply tank comprises an electricity supply agent, an additive and water; the electricity supply agent is at least one of ammonium phosphate, ammonium dihydrogen phosphate and diammonium hydrogen phosphate; the additive is R'-PO4, where R' is an active metal ion; by mass percentage, the content of the electricity supply agent in the conductive solution is 1.5-10 wt%, the content of the additive is 0.01-0.10 wt%, and the rest is water.