Preparation method of high-pressure corrosion foil

Abstract

The invention relates to the technical field of high-pressure corrosion foil preparation, in particular to a high-pressure corrosion foil preparation method which comprises the following steps: S1, pretreatment; s2, hole forming treatment is conducted, specifically, the pretreated aluminum foil is placed in a mixed solution of hydrochloric acid, sulfuric acid and aluminum ions, pulse current is applied, and the single period of the pulse current sequentially comprises a current rising stage, a high current stage, a current falling stage and a low current stage; the current density ratio of the high current stage to the low current stage is (5-10): 1, and the lasting time ratio is 1: (8-13); in the high-current stage, the surface current density of the aluminum foil is 2-8A / cm < 2 >, and the lasting time is 0.5-2 seconds; s3, chambering treatment is carried out; and S4, carrying out post-treatment. According to the invention, the number and depth capability of holes in the high-voltage corrosion foil are obviously improved, and the effective specific surface area of the aluminum foil is increased, so that the specific volume of the corrosion foil under specific voltage is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-voltage etching foil preparation, and more particularly to a high-voltage etching foil preparation method. BACKGROUND

[0002] With the rapid development of new energy automobile, wind power, smart phone and other industries, aluminum electrolytic capacitors are constantly evolving towards high capacity, high strength and miniaturization, which puts higher and higher requirements on the specific capacity of the anode etching foil, a key component in aluminum electrolytic capacitors. The production process of anode etching foil mainly includes basic steps such as pretreatment, pore forming, hole expanding, post-treatment and drying. Among them, the traditional production process of pore forming often uses single-stage pore forming. Due to the gradual decay of the current applied at a time, the density and depth of the pores are not uniform, and the specific capacity of the high-voltage etching foil prepared is low, which is difficult to meet the use requirements. In recent years, the pore forming step of anode etching foil has gradually upgraded from single-stage pore forming process to multi-stage pore forming process. Through stage-by-stage control, a gradient pore size or multi-level pore structure can be formed, and the pore depth and density are more uniform, thereby greatly improving the product specific capacity.

[0003] However, the multi-stage pore forming process has high equipment complexity, and the production line needs to be equipped with a complex control system and multiple treatment tanks, which not only increases the investment cost of the equipment, but also increases the difficulty of maintenance and operation. At the same time, the widespread use of multi-stage pore forming process has led to a large number of production lines designed according to single-stage pore forming process being idle, further increasing the burden on enterprises.

[0004] Therefore, how to improve the performance of etching foil prepared by single-stage pore forming production line without changing the overall structure of single-stage pore forming production line has become a problem to be solved. SUMMARY

[0005] The purpose of the present application is to overcome the problem of low specific capacity of high-voltage etching foil prepared by single-stage pore forming process in the prior art, which leads to a large number of single-stage pore forming production lines being idle, and to provide a high-voltage etching foil preparation method and electrode plate, which improves the performance of etching foil without changing the overall structure of single-stage pore forming production line.

[0006] To solve the above technical problems, the technical solution adopted by the present application is: A high-voltage etching foil preparation method is provided, comprising the following steps: S1, pretreatment; S2, hole forming treatment: the aluminum foil treated by the pretreatment is placed in a mixed solution of hydrochloric acid, sulfuric acid and aluminum ions and a pulse current is applied, a single cycle of the pulse current comprising in turn a current rising phase, a high current phase, a current falling phase and a low current phase; the ratio of the current density in the high current phase to the low current phase is (5-10):1, and the ratio of the duration is 1:(8-13); the surface current density of the aluminum foil in the high current phase is 2-8 A / cm 2 , and the duration is 0.5-2 seconds; S3, hole expanding treatment: the aluminum foil treated by the hole forming treatment is subjected to hole expanding corrosion; S4, post-treatment: the aluminum foil treated by the hole expanding treatment is subjected to post-treatment, thereby obtaining the high-voltage etched foil.

[0007] The preparation method of the high-voltage etched foil of the application first effectively removes impurities on the surface of the aluminum foil through S1 pretreatment, and forms uniformly distributed defect points on the surface of the aluminum foil, which is beneficial to subsequent uniform hole forming.

[0008] In the hole forming treatment S2, the hole forming effect is adjusted by adjusting the waveform of the pulse current, wherein the current density in the high current phase can not only break through the passivation layer of the oxide film on the surface of the aluminum foil, promote the instantaneous start of the corrosion reaction, induce the uniform generation of a large number of small etching hole nuclei on the surface of the aluminum foil, and provide a uniform substrate for subsequent hole forming, but also can provide a sustained and stable large current to drive a violent electrochemical corrosion and accelerate the hole forming and growth process of the holes, thereby obtaining sufficient hole density. The current density is maintained at a low level in the low current phase, which further refines the hole shape on the surface of the aluminum foil, smoothens the hole wall and refines the hole opening. The ratio of the current density in the high current phase to the low current phase and the ratio of the duration can be adjusted within a certain range to adjust the electrochemical corrosion kinetics on the surface of the aluminum foil, optimize the formation and evolution of the hole structure, and significantly increase the density and depth of the holes on the aluminum foil, thereby improving the specific capacity of the etched foil while maintaining good bending performance.

[0009] The hole depth is further increased in the hole expanding treatment S3, so that it can meet the use requirements of the capacitor. The post-treatment S4 is mainly to clean the residual aluminum ions on the surface of the aluminum foil and the holes, increase the cleanliness of the etched foil surface, and obtain a high-capacity etched foil suitable for aluminum electrolytic capacitors.

[0010] The application significantly improves the number and depth of the holes in the high-voltage etched foil by pulse current in the hole forming treatment process, increases the effective specific surface area of the aluminum foil, and thereby improves the specific capacity of the etched foil under a certain voltage. Meanwhile, without changing the overall structure of the single-stage hole forming production line, the performance of the etched foil is improved, the product performance is close to that of the multi-stage hole forming process, the idle single-stage hole forming production line is utilized, and the complexity and production cost of the production line are reduced.

[0011] Preferably, in step S1, the specific process of the pre-treatment is: first immerse the aluminum foil in a phosphoric acid aqueous solution for 60-180 seconds, and then immerse it in a mixed solution of hydrochloric acid and sulfuric acid for 40-80 seconds. The phosphoric acid dissolves the natural oxide film and organic contaminants on the surface of the aluminum foil, and the generated aluminum phosphate can be removed by subsequent pickling to avoid the influence of residual on uniform corrosion. The mixed acid of hydrochloric acid and sulfuric acid can strengthen the cleaning, quickly dissolve metal impurities, and strip the surface adsorbed particles, ensuring that the surface of the aluminum foil reaches the cleanliness required for subsequent pore corrosion. The pre-treatment stage can also provide defect points for subsequent pore corrosion. The phosphoric acid selectively etches the grain boundary region of the aluminum foil to form micron-level depressions on the surface, providing uniform corrosion starting points for the subsequent pore treatment. The mixed solution of hydrochloric acid and sulfuric acid further expands the surface defects through non-selective etching to form high-activity regions, promoting the uniform nucleation of pores in the pore treatment stage.

[0012] Preferably, the temperature of the phosphoric acid aqueous solution is 40-60℃, and the concentration is 0.1-1mol / L; the temperature of the mixed solution of hydrochloric acid and sulfuric acid is 50-85℃, wherein the concentration of hydrochloric acid is 0.65-1.0mol / L, and the concentration of sulfuric acid is 3.0-4.0mol / L. The temperature of the phosphoric acid aqueous solution is controlled at 40-60℃, and the content of phosphoric acid is controlled at 0.1-1mol / L, which can form uniform micro-defects on the surface of the aluminum foil by mild etching of the oxide film and grain boundary, providing high-density nucleation sites for subsequent corrosion; the temperature of the mixed solution of hydrochloric acid and sulfuric acid is maintained at 50-85℃, which can further deeply clean the surface impurities, and cooperatively regulate the corrosion rate by using the rapid solubility of hydrochloric acid and the high ionic strength of sulfuric acid, laying a uniform and high-activity foundation for pulse pore corrosion while removing aluminum phosphate residues, and improving the corrosion pore density.

[0013] Preferably, in step S2, the temperature of the mixed solution of hydrochloric acid, sulfuric acid and aluminum ions is 68-80℃, wherein the concentration of hydrochloric acid is 0.65-1.0mol / L, the concentration of sulfuric acid is 3.0-4.5mol / L, and the concentration of aluminum ions is 0.1-0.3mol / L. In the mixed solution of hydrochloric acid (0.65-1.0mol / L), sulfuric acid (3.0-4.5mol / L) and aluminum ions (0.1-0.3mol / L) at 68-80℃, the corrosion process is dynamically regulated by multi-stage pulse current, wherein the aluminum ions can inhibit excessive corrosion, and the mixed acid of hydrochloric acid and sulfuric acid can balance the reaction rate, and the multi-cycle pulse current can significantly improve the pore density, depth and uniformity, increase the specific capacity of the aluminum foil, and balance the mechanical strength and process stability.

[0014] Preferably, in step S2, the number of pulse current cycles is 2-5. Multiple groups of pulse current cycles can increase the number and depth of holes in the high-voltage etched foil, increase the specific capacity by increasing the specific surface area, and the number of pulse current cycles can be selected according to the performance requirements of the aluminum foil in actual production. For the hole nucleation and growth stages, respectively, the dense hole nuclei are promoted in the high current stage of the pulse current, and the uniform expansion of the holes is regulated in the low current stage to avoid uneven structure. Controlling the number of pulse current cycles to be more than 2 ensures that the number and depth of holes etched on the aluminum foil can meet the use requirements of aluminum electrolytic capacitors in high-voltage environments. The number of pulse current cycles can be controlled to be less than 5 to avoid excessive etching of the aluminum foil surface, which can cause a significant decrease in the mechanical properties of the aluminum foil. At the same time, when the pulse current increases to more than 5, the processing cost is further increased, while the performance improvement of the aluminum foil is small, and the performance gain is marginal.

[0015] Preferably, in step S2, the duration of the current rising stage is less than or equal to 0.5 seconds, and the duration of the current falling stage is 1-5 seconds. By strong current impact in a very short time, the initial dynamics of etching can be significantly optimized, the aluminum foil surface is instantaneously broken down, the current density increases sharply, the local electric field strength exceeds the critical etching potential of the aluminum foil, and a large number of high-density etching nuclei are uniformly generated on the surface to provide a basis for subsequent hole expansion.

[0016] In the current falling stage, the current slowly decreases from the peak value within 1-5 seconds, which slows down the reaction rate, prevents stress concentration at the hole opening caused by sudden stopping of the current, gradually reduces the flow to maintain local micro-area activity, inhibits the generation of Al(OH)3 passivation film by aluminum ion hydrolysis, reduces the hydrogen evolution rate, reduces the mechanical impact of bubbles on the hole wall, and improves the integrity of the hole structure.

[0017] Preferably, in step S2, the pulse current is applied by using a special-shaped electrode, and the special-shaped electrode is provided with a plurality of groups of protrusions parallel to each other on the side facing the aluminum foil, and the protrusions are in the shape of a right-angled trapezoid with the upper base length being less than the lower base length. The electrode plate is provided with protrusions on the side facing the aluminum foil, and the distance between the electrode plate and the aluminum foil is controlled to regulate the current density on the surface of the aluminum foil. When the distance between the electrode plate and the aluminum foil decreases, the current density on the surface of the aluminum foil increases; when the distance between the electrode plate and the aluminum foil increases, the current density on the surface of the aluminum foil decreases. The shape of the protrusions is set to a right-angled trapezoid with the upper base length being less than the lower base length, the distance between the electrode plate and the aluminum foil is controlled to rapidly decrease first, then remain unchanged, and then slowly increase, and finally remain unchanged, so that the current density on the surface of the aluminum foil meets the pulse current rule, a plurality of groups of protrusions correspond to a plurality of pulse current cycles, and the pulse current etching is realized during the hole forming process, thereby improving the number and depth of holes in the high-voltage etched foil, increasing the effective specific surface area of the aluminum foil, and further improving the specific capacity of the etched foil under a certain voltage.

[0018] Preferably, in step S2, a zero current phase is provided between the pulse currents, and the aluminum foil is clamped by the servo bar in the zero current phase. By providing servo bars on both sides of the aluminum foil, the passing aluminum foil is clamped in the zero current phase between adjacent pulse currents, the swing amplitude of the aluminum foil is reduced, the performance of the etched foil product produced by the pulse current is more stable, and the capacity deviation is significantly improved.

[0019] The preparation method of the present application can also provide servo bars on both sides of the aluminum foil, thereby reducing the swing amplitude of the aluminum foil during the etching process, ensuring the stability of the current density on the surface of the aluminum foil, and improving the stability of the product performance and reducing the capacity deviation.

[0020] Preferably, after step S2 and before step S3, the aluminum foil is washed with deionized water at room temperature. After the etching treatment in step S2, washing with deionized water at room temperature can quickly terminate the electrochemical reaction, remove the residual acid electrolyte and corrosion products on the surface of the aluminum foil and in the pores, and avoid the occurrence of non-controlled side reactions or local excessive corrosion caused by residual acid in the subsequent etching process. At the same time, water washing can neutralize the surface pH value, reduce the plugging of the pores caused by the hydrolysis of aluminum ions to form Al(OH)3 precipitate, ensure the uniform reactivity of the nitric acid system in the etching process, improve the integrity and etching efficiency of the pore structure, and provide a clean surface for the subsequent formation process.

[0021] Preferably, in step S3, the specific process of the etching process is to place the aluminum foil in a mixed solution of nitric acid, phosphoric acid and aluminum ions and apply a direct current. By further electrolytic corrosion of the aluminum foil in the environment of the mixed solution of nitric acid, phosphoric acid and aluminum ions under the action of the direct current, the depth of the etching hole is increased, and the specific capacity is improved.

[0022] Preferably, in step S3, the temperature of the mixed solution of nitric acid, phosphoric acid and aluminum ions is 68-78℃, the concentration of nitric acid is 0.2-0.8 mol / L, the concentration of phosphoric acid is 0.2-0.8 wt%, and the concentration of aluminum ions is 0.1-0.4 mol / L. Nitric acid has strong oxidizing property and dominates longitudinal etching, preferentially etching the bottom of the hole, promoting the longitudinal extension of the pore, and forming a high depth-to-diameter ratio structure; phosphoric acid regulates the morphology of the hole wall, selectively modifies the hole wall, and improves the roughness and specific surface area of the hole wall; aluminum ions stabilize the reaction interface, inhibit excessive corrosion at the hole opening, maintain the stability of the pore structure, and balance the activity of the electrolyte to avoid passivation caused by sudden increase of local pH.

[0023] Preferably, in step S3, the current density of the direct current is 0.1-0.5 A / cm 2, the power-on time is 200-600 seconds. The low current density avoids hole wall collapse, ensures that the corrosion reaction extends longitudinally to the hole bottom at a controllable rate, and forms a uniform high depth-to-diameter ratio structure. The longer processing time allows the phosphoric acid to slowly modify the hole wall, increase the rough surface, and increase the specific surface area while maintaining the mechanical strength of the channel. The combination of current density and time adjusts the nitric acid consumption rate to avoid corrosion stagnation caused by local depletion of H⁺. After the hole expansion treatment, the specific volume can be significantly increased, the high-pressure performance can be optimized, and the efficiency and structural stability can be considered.

[0024] Preferably, in step S4, the specific process of the post-treatment is to place the aluminum foil subjected to the hole expansion treatment in a sulfuric acid aqueous solution for immersion, then wash the aluminum foil with deionized water at room temperature, and finally dry the aluminum foil. The temperature of the sulfuric acid aqueous solution is preferably 50-80℃, the sulfuric acid content is 3-10 wt%, and the immersion time is 2-5 minutes. The sulfuric acid solution efficiently dissolves the by-products such as nitrate and aluminum phosphate remaining in the hole expansion stage, and removes impurities in the channel; the sulfuric acid environment promotes the formation of a dense composite passivation film on the surface of the aluminum foil, and after the acid residues are completely removed by water washing, the stress in the channel is eliminated by drying to reduce microcracks, finally obtaining a high-purity, low-stress etching foil with improved specific volume stability, meeting the long-service requirement of high-voltage capacitors.

[0025] Compared with the prior art, the beneficial effects of the present application are: 1. The preparation method of the present application significantly improves the number and depth of holes in the high-voltage etching foil, increases the effective specific surface area of the aluminum foil, and thus improves the specific capacity of the etching foil under a specific voltage, while maintaining good bending performance; 2. The preparation method of the present application does not need to make substantial changes to the single-stage hole production line, and can obtain etching foil performance close to that of multi-stage hole products, reducing the complexity and cost of the production line, and improving production efficiency and flexibility. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic diagram of the pulse current in Example One; Figure 2 is a schematic diagram of the pulse current in Example Two; Figure 3 is a schematic diagram of the pulse current in Example Three; Figure 4 is a schematic diagram of the pulse current in Example Four; Figure 5 is a schematic diagram of the electrode plate structure. DETAILED DESCRIPTION

[0027] The application will be further described below in conjunction with the specific embodiments. In the drawings, only for exemplary illustration, the representations are only schematic diagrams, not physical diagrams, and cannot be understood as limiting the patent; in order to better illustrate the embodiments of the application, some components of the drawings will be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings can be omitted.

[0028] The same or similar reference numerals in the drawings of the embodiments of the application correspond to the same or similar components; in the description of the application, it should be understood that if the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right" and the like are based on the orientations or positional relationships shown in the drawings, only for the convenience of describing the application and simplifying the description, and not to indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the positional relationship described in the drawings is only for exemplary illustration, and cannot be understood as limiting the patent, for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0029] Embodiment one The present embodiment is the first embodiment of the preparation method of high-pressure corrosion foil, comprising the following steps: (1) pretreatment: first immerse the aluminum foil in a 50℃ aqueous solution containing 0.30 mol / L phosphoric acid for 120 seconds, then immerse the aluminum foil in a 60℃ mixed solution containing 1 mol / L hydrochloric acid and 3.5 mol / L sulfuric acid for 50 seconds; (2) pore forming treatment: immerse the aluminum foil pretreated in step (1) in a 70℃ mixed solution containing 1.0 mol / L hydrochloric acid, 3.5 mol / L sulfuric acid and 0.2 mol / L aluminum ions, and apply a pulse current. The pulse current is as shown in Figure 1 , including 2 cycles, each cycle in turn includes a current rising stage, a high current stage, a current falling stage and a low current stage, the current rising stage raises the current density to 4A / cm 2 in 0.5 seconds; the current density of the high current stage is 4A / cm 2 , the duration is 1 second; the current density of the current falling stage decreases from 4A / cm 2 to 0.5A / cm 2 in 2 seconds; the current density of the low current stage is 0.5A / cm 2 , the duration is 10 seconds. After completing the application of pulse current, the aluminum foil is washed with deionized water at room temperature; (3) hole expansion treatment: the aluminum foil treated in step (2) is placed in a 70℃ aqueous solution containing 0.5 mol / L nitric acid, 0.3 mol / L aluminum ions and 0.3 wt% phosphoric acid for direct current hole expansion corrosion, the current density of direct current hole expansion corrosion is 0.25 A / cm 2 , and the power-on time is 400 seconds; (4) post-treatment: the aluminum foil treated in step (3) is soaked in a 75℃ aqueous solution containing 5 wt% sulfuric acid for 3 minutes, then the aluminum foil is washed with deionized water at room temperature, and the aluminum foil treated by room temperature water washing is dried in an oven at 100℃ for 15 minutes to obtain a high-pressure corrosion foil.

[0030] In step (2) of the embodiment, a zero current stage is provided between the pulse currents, and a servo bar is used to clamp the aluminum foil in the zero current stage. By providing servo bars on both sides of the aluminum foil, the passing aluminum foil is clamped in the zero current stage between adjacent pulse currents, the swing amplitude of the aluminum foil is reduced, and the performance of the corrosion foil product produced by the pulse current is more stable, and the capacity deviation is significantly improved.

[0031] As shown in Figure 5 , the electrode plate in the embodiment is provided with a plurality of groups of parallel protrusions on the side facing the aluminum foil, and the protrusions are in the shape of a right-angled trapezoid with the upper base length being less than the lower base length. The waveform and period of the pulse current are adjusted by adjusting the upper base length, lower base length, length of two sides, distance between adjacent protrusions, and number of protrusions of the right-angled trapezoid. In this embodiment, in step (2), a special-shaped electrode is used to apply pulse current, as shown in Figure 5 , the special-shaped electrode is provided with a plurality of groups of parallel protrusions on the side facing the aluminum foil, and the protrusions are in the shape of a right-angled trapezoid with the upper base length being less than the lower base length. The electrode plate is provided with protrusions on the side facing the aluminum foil, and the distance between the electrode plate and the aluminum foil is controlled to adjust the current density on the surface of the aluminum foil. When the distance between the electrode plate and the aluminum foil decreases, the current density on the surface of the aluminum foil increases; when the distance between the electrode plate and the aluminum foil increases, the current density on the surface of the aluminum foil decreases. The shape of the protrusions is set to a right-angled trapezoid with the upper base length being less than the lower base length, and when the aluminum foil passes the position of the protrusions, the distance between the electrode plate and the aluminum foil is controlled to rapidly decrease first, remain unchanged later, and then slowly increase, and finally remain unchanged, so that the current density on the surface of the aluminum foil meets the pulse current rule, and a plurality of groups of protrusions correspond to a plurality of groups of pulse currents, thereby realizing pulse current corrosion in the hole expansion treatment process of step (2).

[0032] Example Two This embodiment is the second embodiment of the method for preparing a high-pressure corrosion foil, which is similar to the first embodiment, except that in step (2), the pulse current includes 3 periods, and the duration of the high current stage is 1.5 seconds, as shown in Figure 2 .

[0033] Example 3 This example is a third embodiment of the method for preparing high pressure etching foil, which is similar to example 1, except that in step (2), the pulse current comprises 4 cycles, as shown in Figure 3 .

[0034] Example 4 This example is a fourth embodiment of the method for preparing high pressure etching foil, which is similar to example 1, except that in step (2), the pulse current comprises 5 cycles, as shown in Figure 4 .

[0035] Example 5 This example is a fifth embodiment of the method for preparing high pressure etching foil, which is similar to example 1, except that in step (2), the current density of the high current stage is 6 A / cm 2 , and the current density of the low current stage is 1.2 A / cm 2 .

[0036] Example 6 This example is a fifth embodiment of the method for preparing high pressure etching foil, which is similar to example 1, except that in step (2), the duration of the high current stage is 0.8 seconds, and the duration of the low current stage is 10 seconds.

[0037] Comparative Example 1 In comparative example 1, a high pressure etching foil is prepared by using a single-stage constant current hole forming process, which is different from example 1 in that in step (2), the pulse current is replaced by a constant current, the current density of the constant current is 2.5 A / cm 2 , and the duration is 60 seconds, and no servo rod is provided.

[0038] Comparative Example 2 This comparative example is similar to comparative example 1, except that in step (2), a multi-stage hole forming process is used, which includes 5 stages of electrolytic etching hole forming, in which the initial current density is 4 A / cm 2 , for 20 seconds, and then the current density decays to 0.05 A / cm 2 for 40 seconds, and each stage of electrolytic etching hole forming is accompanied by chemical soaking and air contact processes in the conventional multi-stage hole forming process, and no servo rod is provided, and the rest of the process is the same as comparative example 1.

[0039] Comparative Example 3 This comparative example is similar to example 1, except that in step (2), the current density of the high current stage is 1 A / cm 2, the current density of the low current phase was 0.125 A / cm 2 .

[0040] Comparative Example Four This comparative example is similar to Example One, except that in step (2), the current density of the high current phase was 12 A / cm 2 , the current density of the low current phase was 1.5 A / cm 2 .

[0041] Comparative Example Five This comparative example is similar to Example One, except that in step (2), the current density of the high current phase was 4 A / cm 2 , the current density of the low current phase was 0.3 A / cm 2 .

[0042] Comparative Example Six This comparative example is similar to Example One, except that in step (2), the current density of the high current phase was 4 A / cm 2 , the current density of the low current phase was 1 A / cm 2 .

[0043] Comparative Example Seven This comparative example is similar to Example One, except that in step (2), the current density of the low current phase was 0 A / cm 2 .

[0044] Comparative Example Eight This comparative example is similar to Example One, except that in step (2), the duration of the low current phase was 3 s.

[0045] Comparative Example Nine This comparative example is similar to Example One, except that in step (2), the duration of the high current phase was 1 s, and the duration of the low current phase was 3 s.

[0046] Comparative Example Ten This comparative example is similar to Example One, except that in step (2), the duration of the high current phase was 1 s, and the duration of the low current phase was 16 s.

[0047] The high voltage etched foils obtained in Example One, Example Two, Example Three, Example Four, Example Five, Example Six, Comparative Example One, Comparative Example Two, Comparative Example Three, Comparative Example Four, Comparative Example Five, Comparative Example Six, Comparative Example Seven, Comparative Example Eight, Comparative Example Nine, Comparative Example Ten were subjected to specific capacity testing and bending strength testing and the capacity deviation was calculated. The testing methods and capacity deviation calculation methods used are shown below.

[0048] Specific capacity test method: the high-voltage corrosion foil is subjected to formation treatment in a 10% mass fraction boric acid solution at 90°C at 520V, and then detected using a static capacity tester ZX8516B of Changzhou Zhixin Precision Electronics Co., Ltd., with a measurement accuracy of ±2%, a test frequency of 120±5HZ, and a measurement voltage kept below 0.5Vrms, and a tank solution composed of 1000mL of pure water and 80g of ammonium pentaborate, at a test temperature of 30±2°C.

[0049] Bending performance test method: a high-voltage corrosion foil with a specification of 10mm*150mm is selected, wherein the sample burr is less than 0.1mm, and a MIT-DA model bending tester of YAFENG Co., Ltd. is used, with a bending curvature radius of 1.0±0.1mm, a load of 2.5±0.5N, a bending angle of 90±2°, a bending back-and-forth speed of 6 times / S, and an upper and lower clamp spacing of 70±2mm.

[0050] Capacity deviation calculation method: first, the average capacity value is calculated , and then the capacity deviation is calculated according to the average capacity value , with the calculation formula as follows:

[0051]

[0052] In the formula, is the maximum specific capacity at the foil head of the aluminum foil roll, is the minimum specific capacity at the foil head of the aluminum foil roll, is the maximum specific capacity at the foil tail of the aluminum foil roll, is the minimum specific capacity at the foil tail of the aluminum foil roll.

[0053] Table 1 Performance table of corrosion foils prepared in examples and comparative examples

[0054] As can be seen from the comparison of examples and comparative examples 1 and 2, the high-voltage corrosion foil prepared by the method in the present application has higher specific capacity and bending performance than the product obtained by the traditional single-stage pore-forming process production line; compared with the product obtained by the multi-stage pore-forming process production line, the aluminum foil in the present application simplifies the production process, reduces the equipment complexity and production cost while maintaining similar specific capacity. In addition, since the preparation method of the present application can set a servo plate, the performance of the obtained corrosion foil product is more stable, and the capacity deviation is significantly improved.

[0055] The parameters of the pulse current in comparative examples 3 to 10 are not suitable, the electrochemical corrosion kinetics of the aluminum foil surface is not properly controlled, and the optimization degree of the formation and evolution of the pore structure is not enough, resulting in poor specific capacity and bending performance.

[0056] In the specific contents of the foregoing specific embodiments, each technical feature can be combined arbitrarily without contradiction. In order to make the description simple, all possible combinations of the foregoing technical features are not described, but as long as the combinations of the technical features do not contradict, they should be considered as the scope of the present disclosure.

[0057] Obviously, the above embodiments of the present application are merely exemplary and are not intended to limit the implementation modes of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary and also impossible to exhaust all the implementation modes. Any modification, equivalent replacement and improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the claims of the present application.

Claims

1. A method of producing a high pressure etching foil, characterized in that, The method comprises the following steps: S1, pre-treatment; S2, hole forming treatment: placing the aluminum foil subjected to the pre-treatment in a mixed solution of hydrochloric acid, sulfuric acid and aluminum ions and applying a pulse current, wherein a single cycle of the pulse current comprises, in sequence, a current rising stage, a high current stage, a current falling stage and a low current stage; the ratio of the current density in the high current stage to the current density in the low current stage is (5-10):1, and the ratio of the duration of the high current stage to the duration of the low current stage is 1:(8-13); the surface current density of the aluminum foil in the high current stage is 2-8 A / cm2, and the duration is 0.5-2 seconds; S3, hole expanding treatment: performing hole expanding corrosion on the aluminum foil subjected to the hole forming treatment; S4, post-treatment: performing post-treatment on the aluminum foil subjected to the hole expanding treatment, thereby obtaining the high-pressure corrosion foil.

2. The method of producing a high pressure etching foil according to claim 1, characterized in that, In step S1, the specific process of the pre-treatment is as follows: first, immersing the aluminum foil in a phosphoric acid aqueous solution for 60-180 seconds, and then immersing the aluminum foil in a mixed solution of hydrochloric acid and sulfuric acid for 40-80 seconds.

3. The method for preparing a high voltage corrosion foil according to claim 2, characterized in that: The temperature of the phosphoric acid aqueous solution is 40-60°C, and the concentration is 0.1-1 mol / L; the temperature of the mixed solution of hydrochloric acid and sulfuric acid is 50-85°C, wherein the concentration of hydrochloric acid is 0.65-1.0 mol / L, and the concentration of sulfuric acid is 3.0-4.0 mol / L.

4. The method of producing a high pressure etching foil according to claim 1, characterized in that, In step S2, the temperature of the mixed solution of hydrochloric acid, sulfuric acid and aluminum ions is 68-80°C, wherein the concentration of hydrochloric acid is 0.65-1.0 mol / L, the concentration of sulfuric acid is 3.0-4.5 mol / L, and the concentration of aluminum ions is 0.1-0.3 mol / L.

5. The method of claim 1, wherein In step S2, the number of cycles of the pulse current is 2-5.

6. The method of producing a high pressure etching foil according to claim 1, characterized in that, In step S2, the duration of the current rising stage is less than or equal to 0.5 seconds, and the duration of the current falling stage is 1-5 seconds.

7. The method of producing a high pressure etching foil according to any one of claims 1 to 6, characterized in that, In step S2, the pulse current is applied by using a special-shaped electrode, wherein a plurality of groups of protrusions parallel to each other are arranged on the side of the special-shaped electrode facing the aluminum foil, and the protrusions are in the shape of right-angled trapezoids with the upper base length being less than the lower base length.

8. The method of producing a high pressure etching foil according to any one of claims 1 to 6, characterized in that, In step S2, a zero-current stage is provided between the pulse currents, and a servo rod is used to clamp the aluminum foil in the zero-current stage.

9. The method of claim 1, wherein In step S3, the specific process of the hole expanding treatment is as follows: placing the aluminum foil in a mixed solution of nitric acid, phosphoric acid and aluminum ions and applying a direct current.

10. The method of producing a high pressure etching foil according to claim 1, characterized in that, In step S4, the specific process of the post-treatment is as follows: immersing the aluminum foil subjected to the hole expanding treatment in a sulfuric acid aqueous solution, then washing the aluminum foil with deionized water at room temperature, and finally drying the aluminum foil.

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