A method of detecting defects in a low voltage electrode foil erosion layer

Abstract

The application discloses a method for detecting defects of a corrosion layer of a low-voltage electrode foil, and belongs to the technical field of electrode foil manufacturing for capacitors. The method for detecting defects of the corrosion layer of the low-voltage electrode foil comprises the following steps: S1. primary formation; S2. reverse power connection: the foil is connected to a negative electrode of a power supply, a plate is connected to a positive electrode of the power supply, and direct current is applied for treatment; S3. secondary formation; S4. heat treatment; S5. tertiary formation; S6. drying; and S7. cutting the foil, and observing the cutting position of the foil; if there is a delamination phenomenon, it is determined that the corrosion layer of the low-voltage electrode foil has defects. After the corrosion foil is produced, the corrosion foil is subjected to formation, reverse power connection is used in the formation process, the corrosion layer is damaged, and whether the corrosion layer has defects can be detected as soon as possible after the corrosion foil is produced.

Description

Technical Field

[0001] This invention relates to the field of capacitor electrode foil manufacturing technology, and more specifically, to a method for detecting defects in the corrosion layer of low-voltage electrode foil. Background Technology

[0002] Aluminum electrolytic capacitors are energy storage components widely used in the electronics and electrical appliance industry, and anode foil is a crucial raw material for them. The production process for low-voltage anode foil generally involves: aluminum foil → pretreatment → etching treatment → post-treatment → formation treatment → obtaining low-voltage anode foil. Pretreatment removes oil, oxide film, and impurities from the aluminum foil surface, improving its surface condition. Etching treatment uses electrochemical etching to form tunnels of a certain diameter and depth on the aluminum foil surface, increasing its surface area and achieving high specific capacitance. Post-treatment involves cleaning and surface transformation of the etched aluminum foil. Formation treatment utilizes a multi-stage power supply to form an oxide film on the aluminum foil surface.

[0003] High specific capacity is an important criterion for judging the performance of low-pressure anode foil. To improve specific capacity, the method of increasing weight loss is generally adopted. However, excessive weight loss can easily lead to defects in the corrosion layer.

[0004] Because the corrosion process of low-pressure anode foil uses alternating current, the resulting pits are spongy and have a small pore size of only 100-200 nm. Even with a high-magnification scanning electron microscope (SEM), it is difficult to see the morphology of the corrosion layer, let alone the defects within the pits. These defects can lead to surface peeling and foil brittleness during later use, negatively impacting subsequent processes.

[0005] Existing technology discloses an ultrasonic guided wave detection method for micro-perforation defects in positively corroded aluminum foil. This method involves scanning the anolyte foil under test with an ultrasonic guided wave to obtain the actual ultrasonic guided wave signal value, calculating the actual peak value ratio of the detection spectrum, and substituting this value into a regression relationship to obtain the final defect detection result. However, this method addresses the perforation problem of anolyte corroded foil and does not provide any improvements for detecting defects in the corrosion layer.

[0006] Therefore, it is indeed necessary to provide a method for detecting defects in the corrosion layer of low-voltage electrode foil, which can detect defects in the corrosion layer of low-voltage electrode foil as soon as possible after the corrosion foil is prepared, and to inspect and adjust the production line. Summary of the Invention

[0007] The technical problem this invention aims to solve is to overcome the shortcomings and deficiencies of existing low-voltage anode foil corrosion layer defects, which cannot be detected quickly and the production line cannot be inspected and adjusted promptly. This invention provides a method for detecting corrosion layer defects in low-voltage electrode foil. The method involves forming the corrosion foil and using reverse current during the formation process to damage the corrosion layer. After formation, the foil is physically cut, and the damage is inspected. This allows for rapid detection of corrosion layer defects after the corrosion foil is produced, enabling timely inspection and adjustment of the production line and preventing the production of large quantities of low-voltage anode foil with corrosion layer defects.

[0008] The above-mentioned objective of this invention is achieved through the following technical solution:

[0009] A method for detecting corrosion layer defects in low-voltage electrode foil includes the following steps:

[0010] S1. Primary formation: The low-pressure etched foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, DC current is applied, and the voltage is increased to one-quarter to one-half of the final voltage.

[0011] S2. Reverse power application: Place the foil that has undergone primary formation in an ammonium adipate solution, connect the foil to the negative terminal of the power supply, connect the plates to the positive terminal of the power supply, and apply direct current.

[0012] S3. Secondary formation: The foil that has been reverse-energized is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to the final voltage.

[0013] S4. Heat treatment: Heat treatment of the foil that has undergone two-stage formation;

[0014] S5. Three-stage formation: The heat-treated foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, DC current is applied, and the voltage is increased to the final voltage.

[0015] S6. Drying: Drying the foil sheets that have undergone three-stage chemical processing;

[0016] S7. Cutting: Cut the foil and observe the cut area. If there is delamination, it indicates that the corrosion layer of the low-voltage electrode foil is defective.

[0017] Among them, defects refer to situations such as thinning of the hole wall between holes in certain locations of the corrosion layer, or sudden enlargement or shrinkage of holes in certain locations.

[0018] After the low-pressure etched foil of this invention is produced, it undergoes formation. During the formation process, reverse current is applied. When there are defects such as thinning of the hole walls between holes in certain locations of the etched layer, a large amount of H... +Hydrogen bubbles can penetrate into the pore walls and be reduced to hydrogen bubbles. During subsequent heat treatment, these hydrogen bubbles burst, damaging the pore walls and causing delamination of the corrosion layer and foil embrittlement. Therefore, this invention uses reverse current to damage the corrosion layer of the low-voltage corrosion foil, allowing defective areas to be exposed early. After formation, the foil is physically cut, and the damage is inspected to determine if there are defects in the corrosion layer.

[0019] Preferably, in S2, the current density is 0.2-0.6 A / cm². 2 .

[0020] At low current densities, defects caused by corrosion may go undetected in subsequent tests. At high current densities, defects may be created even in normal areas, leading to misjudgments.

[0021] More preferably, in S2, the current density is 0.3-0.5 A / cm². 2 .

[0022] More preferably, in S2, the current density is 0.4 A / cm². 2 .

[0023] Preferably, in S2, the energizing time is 0.5 to 5 minutes.

[0024] In S2, the short power-on time has a limited impact on the corrosion layer and makes it difficult to determine whether the corrosion layer has defects. In contrast, a longer power-on time can damage even a corrosion layer without defects, making it difficult to determine whether the corrosion layer has defects.

[0025] More preferably, in S2, the energizing time is 0.5 to 3 minutes.

[0026] More preferably, in S2, the energizing time is 1 to 2 minutes.

[0027] More preferably, in S2, the power-on time is 1 minute.

[0028] Preferably, in S2, the temperature of the ammonium adipate solution is 5-40℃.

[0029] This invention exposes defects in the corrosion layer early by applying reverse current, which macroscopically manifests as delamination. The ammonium adipate solution acts as a conductor, and the solution temperature can be room temperature.

[0030] More preferably, in S2, the temperature of the ammonium adipate solution is 10-30°C.

[0031] More preferably, in S2, the temperature of the ammonium adipate solution is 15°C.

[0032] In practical applications, the temperature, concentration, current density, and holding time of the ammonium adipate solution in S1, S3, and S5 can be conventional values ​​in the field. For example, the temperature of the ammonium adipate solution can be 60-80℃, the concentration can be 5-15wt%, and the current density can be 0.1-0.3A / cm³. 2 The pressure holding time can be 2-4 minutes.

[0033] In practical applications, in S4, the heat treatment temperature and time can be those commonly used in the field, with the heat treatment temperature being 450-500℃ and the heat treatment time being 1-3 minutes.

[0034] In practical applications, the drying temperature of S6 can be a conventional drying temperature in the field. For example, in S6, the drying temperature can be 100-150℃ and the drying time can be 2-4 minutes.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] This invention discloses a method for detecting defects in the corrosion layer of low-voltage electrode foil. The method involves forming the corrosion foil and using reverse current during the formation process to destroy the corrosion layer. After the formation is completed, the foil is physically cut to detect the damage. This method allows for the rapid detection of potential defects in the corrosion layer after the corrosion foil is produced, enabling the inspection and adjustment of the production line. Attached Figure Description

[0037] Figure 1 The image shows the surface of the low-voltage electrode foil in Example 1 where no delamination is observed at the cut location, indicating that the corrosion layer of the low-voltage electrode foil is defect-free.

[0038] Figure 2 The image shows a surface view of the low-voltage electrode foil in Example 1 where delamination is observed at the cut location, indicating that the corrosion layer of the low-voltage electrode foil is defective.

[0039] Figure 3 The image shows a cross-sectional view of the low-voltage electrode foil in Example 1 where no delamination was observed at the cut point, indicating that the corrosion layer of the low-voltage electrode foil is defect-free.

[0040] Figure 4 The image shows a cross-sectional view of the low-voltage electrode foil in Example 1 where delamination is observed at the cut point, indicating that the corrosion layer of the low-voltage electrode foil is defective. Detailed Implementation

[0041] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0042] Example 1

[0043] A method for detecting corrosion layer defects in low-voltage electrode foil includes the following steps:

[0044] S1. Primary formation: The low-pressure etched foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to one-third of the final voltage.

[0045] S2. Reverse power application: Place the foil that has undergone primary formation in an ammonium adipate solution, connect the foil to the negative terminal of the power supply, connect the plates to the positive terminal of the power supply, and apply direct current.

[0046] S3. Secondary formation: The foil that has been reverse-energized is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to the final voltage.

[0047] S4. Heat treatment: Heat treatment of the foil that has undergone two-stage formation;

[0048] S5. Three-stage formation: The heat-treated foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, DC current is applied, and the voltage is increased to the final voltage.

[0049] S6. Drying: Drying the foil sheets that have undergone three-stage chemical processing;

[0050] S7. Cutting: Cut the foil and observe the cut area. If there is delamination, it indicates that the corrosion layer of the low-voltage electrode foil is defective.

[0051] The low-pressure etched foil has a thickness of 122 μm and a 21Vf specific capacitance of 130 μF / cm. 2 .

[0052] In S1, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 10Vf;

[0053] In S2, the ammonium adipate solution is at a temperature of 15℃, a concentration of 8wt%, and a current density of 0.4A / cm². 2 The power-on time is 1 minute;

[0054] In S3, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 30Vf;

[0055] In S4, the heat treatment temperature is 480℃ and the heat treatment time is 2 minutes.

[0056] In S5, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 30Vf;

[0057] In S6, the drying temperature is 100℃ and the drying time is 3 minutes.

[0058] In S7, cutting is done by using a blade to cut along a direction perpendicular to the foil calendering lines.

[0059] Example 2

[0060] A method for detecting corrosion layer defects in low-voltage electrode foil includes the following steps:

[0061] S1. Primary formation: The low-pressure etched foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to one-third of the final voltage.

[0062] S2. Reverse power application: Place the foil that has undergone primary formation in an ammonium adipate solution, connect the foil to the negative terminal of the power supply, connect the plates to the positive terminal of the power supply, and apply direct current.

[0063] S3. Secondary formation: The foil that has been reverse-energized is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to the final voltage.

[0064] S4. Heat treatment: Heat treatment of the foil that has undergone two-stage formation;

[0065] S5. Three-stage formation: The heat-treated foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, DC current is applied, and the voltage is increased to the final voltage.

[0066] S6. Drying: Drying the foil sheets that have undergone three-stage chemical processing;

[0067] S7. Cutting: Cut the foil and observe the cut area. If there is delamination, it indicates that the corrosion layer of the low-voltage electrode foil is defective.

[0068] The low-pressure etched foil has a thickness of 122 μm and a 21Vf specific capacitance of 130 μF / cm. 2 .

[0069] In S1, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 10Vf;

[0070] In S2, the ammonium adipate solution is at a temperature of 15℃, a concentration of 8wt%, and a current density of 0.2A / cm². 2 The power-on time is 1 minute;

[0071] In S3, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 30Vf;

[0072] In S4, the heat treatment temperature is 480℃ and the heat treatment time is 2 minutes.

[0073] In S5, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 30Vf;

[0074] In S6, the drying temperature is 100℃ and the drying time is 3 minutes.

[0075] In S7, cutting is done by using a blade to cut along a direction perpendicular to the foil calendering lines.

[0076] The difference from Example 1 is:

[0077] In S2, the ammonium adipate solution is at a temperature of 15℃, a concentration of 8wt%, and a current density of 0.2A / cm². 2 The power-on time is 1 minute.

[0078] Example 3

[0079] A method for detecting corrosion layer defects in low-voltage electrode foil includes the following steps:

[0080] S1. Primary formation: The low-pressure etched foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to one-third of the final voltage.

[0081] S2. Reverse power application: Place the foil that has undergone primary formation in an ammonium adipate solution, connect the foil to the negative terminal of the power supply, connect the plates to the positive terminal of the power supply, and apply direct current.

[0082] S3. Secondary formation: The foil that has been reverse-energized is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to the final voltage.

[0083] S4. Heat treatment: Heat treatment of the foil that has undergone two-stage formation;

[0084] S5. Three-stage formation: The heat-treated foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, DC current is applied, and the voltage is increased to the final voltage.

[0085] S6. Drying: Drying the foil sheets that have undergone three-stage chemical processing;

[0086] S7. Cutting: Cut the foil and observe the cut area. If there is delamination, it indicates that the corrosion layer of the low-voltage electrode foil is defective.

[0087] The low-pressure etched foil has a thickness of 122 μm and a 21Vf specific capacitance of 130 μF / cm. 2 .

[0088] In S1, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 10Vf;

[0089] In S2, the ammonium adipate solution is at a temperature of 15℃, a concentration of 8wt%, and a current density of 0.6A / cm². 2 The power-on time is 1 minute;

[0090] In S3, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 30Vf;

[0091] In S4, the heat treatment temperature is 480℃ and the heat treatment time is 2 minutes.

[0092] In S5, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 30Vf;

[0093] In S6, the drying temperature is 100℃ and the drying time is 3 minutes.

[0094] In S7, cutting is done by using a blade to cut along a direction perpendicular to the foil calendering lines.

[0095] The difference from Example 1 is:

[0096] In S2, the ammonium adipate solution is at a temperature of 15℃, a concentration of 8wt%, and a current density of 0.6A / cm². 2 The power-on time is 1 minute.

[0097] Example 4

[0098] A method for detecting corrosion layer defects in low-voltage electrode foil includes the following steps:

[0099] S1. Primary formation: The low-pressure etched foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to one-third of the final voltage.

[0100] S2. Reverse power application: Place the foil that has undergone primary formation in an ammonium adipate solution, connect the foil to the negative terminal of the power supply, connect the plates to the positive terminal of the power supply, and apply direct current.

[0101] S3. Secondary formation: The foil that has been reverse-energized is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to the final voltage.

[0102] S4. Heat treatment: Heat treatment of the foil that has undergone two-stage formation;

[0103] S5. Three-stage formation: The heat-treated foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, DC current is applied, and the voltage is increased to the final voltage.

[0104] S6. Drying: Drying the foil sheets that have undergone three-stage chemical processing;

[0105] S7. Cutting: Cut the foil and observe the cut area. If there is delamination, it indicates that the corrosion layer of the low-voltage electrode foil is defective.

[0106] The low-pressure etched foil has a thickness of 122 μm and a 21Vf specific capacitance of 130 μF / cm. 2 .

[0107] In S1, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 10Vf;

[0108] In S2, the ammonium adipate solution is at a temperature of 15℃, a concentration of 8wt%, and a current density of 0.4A / cm². 2 The power-on time is 0.5 minutes;

[0109] In S3, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 30Vf;

[0110] In S4, the heat treatment temperature is 480℃ and the heat treatment time is 2 minutes.

[0111] In S5, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 30Vf;

[0112] In S6, the drying temperature is 100℃ and the drying time is 3 minutes.

[0113] In S7, cutting is done by using a blade to cut along a direction perpendicular to the foil calendering lines.

[0114] The difference from Example 1 is:

[0115] In S2, the ammonium adipate solution is at a temperature of 15℃, a concentration of 8wt%, and a current density of 0.4A / cm². 2 The power-on time is 0.5 minutes.

[0116] Example 5

[0117] A method for detecting corrosion layer defects in low-voltage electrode foil includes the following steps:

[0118] S1. Primary formation: The low-pressure etched foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to one-third of the final voltage.

[0119] S2. Reverse power application: Place the foil that has undergone primary formation in an ammonium adipate solution, connect the foil to the negative terminal of the power supply, connect the plates to the positive terminal of the power supply, and apply direct current.

[0120] S3. Secondary formation: The foil that has been reverse-energized is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to the final voltage.

[0121] S4. Heat treatment: Heat treatment of the foil that has undergone two-stage formation;

[0122] S5. Three-stage formation: The heat-treated foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, DC current is applied, and the voltage is increased to the final voltage.

[0123] S6. Drying: Drying the foil sheets that have undergone three-stage chemical processing;

[0124] S7. Cutting: Cut the foil and observe the cut area. If there is delamination, it indicates that the corrosion layer of the low-voltage electrode foil is defective.

[0125] The low-pressure etched foil has a thickness of 122 μm and a 21Vf specific capacitance of 130 μF / cm. 2 .

[0126] In S1, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 10Vf;

[0127] In S2, the ammonium adipate solution is at a temperature of 15℃, a concentration of 8wt%, and a current density of 0.4A / cm². 2 The power-on time is 5 minutes;

[0128] In S3, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 30Vf;

[0129] In S4, the heat treatment temperature is 480℃ and the heat treatment time is 2 minutes.

[0130] In S5, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 30Vf;

[0131] In S6, the drying temperature is 100℃ and the drying time is 3 minutes.

[0132] In S7, cutting is done by using a blade to cut along a direction perpendicular to the foil calendering lines.

[0133] The difference from Example 1 is:

[0134] In S2, the ammonium adipate solution is at a temperature of 15℃, a concentration of 8wt%, and a current density of 0.4A / cm². 2 The power-on time is 5 minutes.

[0135] Example 6

[0136] A method for detecting corrosion layer defects in low-voltage electrode foil includes the following steps:

[0137] S1. Primary formation: The low-pressure etched foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to one-third of the final voltage.

[0138] S2. Reverse power application: Place the foil that has undergone primary formation in an ammonium adipate solution, connect the foil to the negative terminal of the power supply, connect the plates to the positive terminal of the power supply, and apply direct current.

[0139] S3. Secondary formation: The foil that has been reverse-energized is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to the final voltage.

[0140] S4. Heat treatment: Heat treatment of the foil that has undergone two-stage formation;

[0141] S5. Three-stage formation: The heat-treated foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, DC current is applied, and the voltage is increased to the final voltage.

[0142] S6. Drying: Drying the foil sheets that have undergone three-stage chemical processing;

[0143] S7. Cutting: Cut the foil and observe the cut area. If there is delamination, it indicates that the corrosion layer of the low-voltage electrode foil is defective.

[0144] The low-pressure etched foil has a thickness of 122 μm and a 21Vf specific capacitance of 130 μF / cm. 2 .

[0145] In S1, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 10Vf;

[0146] In S2, the ammonium adipate solution is at a temperature of 5℃, a concentration of 8wt%, and a current density of 0.4A / cm². 2 The power-on time is 1 minute;

[0147] In S3, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 30Vf;

[0148] In S4, the heat treatment temperature is 480℃ and the heat treatment time is 2 minutes.

[0149] In S5, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 30Vf;

[0150] In S6, the drying temperature is 100℃ and the drying time is 3 minutes.

[0151] In S7, cutting is done by using a blade to cut along a direction perpendicular to the foil calendering lines.

[0152] The difference from Example 1 is:

[0153] In S2, the ammonium adipate solution is at a temperature of 5℃, a concentration of 8wt%, and a current density of 0.4A / cm². 2 The power-on time is 1 minute.

[0154] Example 7

[0155] A method for detecting corrosion layer defects in low-voltage electrode foil includes the following steps:

[0156] S1. Primary formation: The low-pressure etched foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to one-third of the final voltage.

[0157] S2. Reverse power application: Place the foil that has undergone primary formation in an ammonium adipate solution, connect the foil to the negative terminal of the power supply, connect the plates to the positive terminal of the power supply, and apply direct current.

[0158] S3. Secondary formation: The foil that has been reverse-energized is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to the final voltage.

[0159] S4. Heat treatment: Heat treatment of the foil that has undergone two-stage formation;

[0160] S5. Three-stage formation: The heat-treated foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, DC current is applied, and the voltage is increased to the final voltage.

[0161] S6. Drying: Drying the foil sheets that have undergone three-stage chemical processing;

[0162] S7. Cutting: Cut the foil and observe the cut area. If there is delamination, it indicates that the corrosion layer of the low-voltage electrode foil is defective.

[0163] The low-pressure etched foil has a thickness of 122 μm and a 21Vf specific capacitance of 130 μF / cm. 2 .

[0164] In S1, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 10Vf;

[0165] In S2, the ammonium adipate solution is at a temperature of 40℃, a concentration of 8wt%, and a current density of 0.4A / cm². 2 The power-on time is 1 minute;

[0166] In S3, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 30Vf;

[0167] In S4, the heat treatment temperature is 480℃ and the heat treatment time is 2 minutes.

[0168] In S5, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 30Vf;

[0169] In S6, the drying temperature is 100℃ and the drying time is 3 minutes.

[0170] In S7, cutting is done by using a blade to cut along a direction perpendicular to the foil calendering lines.

[0171] The difference from Example 1 is:

[0172] In S2, the ammonium adipate solution is at a temperature of 40℃, a concentration of 8wt%, and a current density of 0.4A / cm². 2 The power-on time is 1 minute.

[0173] The rest is the same as in Example 1, and will not be repeated here.

[0174] Comparative Example 1

[0175] A method for detecting corrosion layer defects in low-voltage electrode foil includes the following steps:

[0176] S1. Primary formation: The low-pressure etched foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to one-third of the final voltage.

[0177] S2. Secondary formation: The foil that has been reverse-energized is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to the final voltage.

[0178] S3. Heat treatment: Heat treatment of the foil that has undergone two-stage formation;

[0179] S4. Three-stage formation: The heat-treated foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, DC current is applied, and the voltage is increased to the final voltage.

[0180] S5. Drying: Drying the foil sheets that have undergone three-stage chemical processing;

[0181] S6. Cutting: Cut the foil and observe the cut area. If there is delamination, it indicates that the corrosion layer of the low-voltage electrode foil is defective.

[0182] The low-pressure etched foil has a thickness of 122 μm and a 21Vf specific capacitance of 130 μF / cm. 2 .

[0183] In S1, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 10Vf;

[0184] In S2, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 30Vf;

[0185] In S3, the heat treatment temperature is 480℃ and the heat treatment time is 2 minutes.

[0186] In S4, the ammonium adipate solution is at a temperature of 70℃, a concentration of 8wt%, and a current density of 0.15A / cm². 2 The holding time is 3 minutes, and the pressure is increased to 30Vf;

[0187] In S5, the drying temperature is 100℃ and the drying time is 3 minutes.

[0188] In S6, cutting is done by using a blade to cut along a direction perpendicular to the calendering lines of the foil.

[0189] The difference from Example 1 is:

[0190] Excluding S2 reverse power-on.

[0191] Result detection

[0192] (1) Observe the delamination phenomenon at the cut part of the foil using a metallographic microscope:

[0193] Delamination level:

[0194] from Figure 1 As can be seen, there is no delamination at the cut edge of the foil, indicating that the low-voltage electrode foil is corroded.

[0195] from Figure 2 It can be seen that there is delamination at the cut part of the foil, which indicates that the corrosion layer of the low-voltage electrode foil is defective.

[0196] The delamination level is determined by the distance h between the edge of the delamination area and the cutting area, as shown in Table 1 below.

[0197] Table 1

[0198]

[0199] The severity of delamination is graded as follows: 0 < 1 < 2 < 3 < 4 < 5, with grade 5 being severe delamination. A delamination grade of 0 is defined as the distance h between the edge of the delamination area and the cut area being ≤ 0.1 mm, indicating almost no delamination and a defect-free corrosion layer.

[0200] (2) Use SEI to observe the cut part of the foil.

[0201] from Figure 3 As can be seen at the cut point of the foil, this indicates that the corrosion layer of the low-voltage electrode foil is free of defects.

[0202] from Figure 4 It can be seen that delamination occurred at the cut point of the foil. If this phenomenon occurs, it can be determined that the corrosion layer of the low-voltage electrode foil is defective.

[0203] The specific test results are shown in Table 3 below:

[0204]

[0205]

[0206] As can be seen from the above data, the method for detecting defects in the corrosion layer of low-voltage electrode foil of the present invention destroys the corrosion layer by adding a reverse energizing step between the primary and secondary formation processes. After formation is completed, the foil is physically cut and the damage to the foil is detected. This allows for the rapid detection of whether there are defects in the corrosion layer after the corrosion foil is produced.

[0207] As can be seen from Comparative Example 1, when the reverse energizing step S2 is cancelled, the delamination level of the low-voltage electrode foil corrosion layer is 0, indicating that there is almost no delamination and the corrosion layer is deemed to have no defects.

[0208] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for detecting defects in the corrosion layer of a low-voltage electrode foil, characterized in that, The steps include the following: S1. Primary formation: The low-pressure etched foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to one-quarter to one-half of the final voltage. S2. Reverse power application: Place the foil that has undergone primary formation in an ammonium adipate solution, connect the foil to the negative terminal of the power supply, connect the plates to the positive terminal of the power supply, and apply direct current. S3. Secondary formation: The foil that has been reverse-energized is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, and a direct current is applied to boost the voltage to the final voltage. S4. Heat treatment: Heat-treat the foil that has undergone two-stage formation; S5. Three-stage formation: The heat-treated foil is placed in an ammonium adipate solution, the foil is connected to the positive terminal of the power supply, the plates are connected to the negative terminal of the power supply, DC current is applied, and the voltage is increased to the final voltage. S6. Drying: Drying the foil sheets that have undergone three-stage chemical processing; S7. Cutting: Cut the foil and observe the cut area. If there is delamination, it indicates that the corrosion layer of the low-voltage electrode foil is defective. In S2, the current density is 0.2-0.6 A / cm². 2 The power-on time is 0.5-5 minutes.

2. The method for detecting corrosion layer defects in low-voltage electrode foil as described in claim 1, characterized in that, In S2, the current density is 0.3-0.5 A / cm². 2 .

3. The method for detecting corrosion layer defects in low-voltage electrode foil as described in claim 1, characterized in that, In S2, the power-on time is 1-2 minutes.

4. The method for detecting corrosion layer defects in low-voltage electrode foil as described in claim 1, characterized in that, In S2, the temperature of the ammonium adipate solution is 5-40℃.

5. The method for detecting corrosion layer defects in low-voltage electrode foil as described in claim 4, characterized in that, In S2, the temperature of the ammonium adipate solution is 10-30℃.

6. The method for detecting corrosion layer defects in low-voltage electrode foil as described in claim 1, characterized in that, In S1, S3, and S5, the ammonium adipate solution is at a temperature of 60-80℃, a concentration of 5-15wt%, and a current density of 0.1-0.3 A / cm². 2 The pressure holding time is 2-4 minutes.

7. The method for detecting corrosion layer defects in low-voltage electrode foil as described in claim 1, characterized in that, In S4, the heat treatment temperature is 450-500℃ and the heat treatment time is 1-3 minutes.

8. The method for detecting corrosion layer defects in low-voltage electrode foil as described in claim 1, characterized in that, In S6, the drying temperature is 100-150℃ and the drying time is 2-4 minutes.

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