Low-voltage formation method which reduces post-hydration voltage rise time

Abstract

The present invention relates to the technical field of formed foils, and specifically relates to a low-voltage formation method which reduces post-hydration voltage rise time. The low-voltage formation method which reduces post-hydration voltage rise time of the present invention comprises six stages of formation, phosphoric acid treatment, first post-treatment, phosphoric acid treatment, second post-treatment, phosphoric acid treatment, heat treatment, and third post-treatment. The anodized aluminium foil obtained via the formation method of the present invention has improved capacitance and improved hydration resistance, such that compared with an original process, the voltage rise time after one hour of hydration treatment is reduced by approximately 60% and the voltage rise time after six hours of treatment is reduced by approximately 40%, thus significantly improving hydration resistance.

Description

Low-voltage formation method for reducing post-hydration boost time TECHNICAL FIELD

[0001] The present application relates to the technical field of formation foil, in particular to a low-voltage formation method for reducing post-hydration boost time. BACKGROUND

[0002] Low-voltage formation foil, as an important raw material for aluminum electrolytic capacitors, has a wide range of applications in various fields. With the continuous progress of technology and optimization of process, the performance of low-voltage formation foil will be further improved. The current low-voltage formation foil is treated by special process, has stable electrochemical performance, and can maintain good capacitance characteristics in various environments; compared with other types of capacitor materials, low-voltage formation foil can provide greater capacitance, meet the demand for high energy density, and has a long service life and other advantages. However, most of the current low-voltage formation foil products have the problem of long hydration time. The hydration resistance is a key factor restricting the service life and reliability of aluminum electrolytic capacitors. The oxide film layer grown on the surface of the aluminum electrode foil serves as the working medium of the aluminum electrolytic capacitor, and directly contacts with the aqueous electrolyte during work. The water molecules in the electrolyte are adsorbed on the surface of the oxide film to form a hydrated aluminum oxide film, thereby destroying the insulating layer structure of the aluminum anode oxide film, leading to a decrease in the dielectric properties of the electrode foil, an increase in the leakage current of the capacitor, and ultimately resulting in the failure of the aluminum electrolytic capacitor, thus failing to meet the market demand for high-performance electrode foil.

[0003] Patent technology document CN202110402809.7 discloses a formation method of low-voltage formation foil and the prepared low-voltage formation foil. The aluminum foil is formed in a water solution of adipate salt, washed with water, then passivated in a phosphoric acid solution, and then heat treated and formed with low-concentration phosphoric acid to prepare a low-voltage formation foil with a leakage current ≤14 μF / cm 2 , which can effectively improve the stability of the product. Although the invention can make the leakage current lower, it does not make actual research on the hydration resistance, which will inevitably affect its use in actual situation. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a low-voltage formation method for reducing post-hydration boost time to solve the problem of poor hydration resistance of traditional formation foil.

[0005] In order to achieve the above purpose, the present application provides a low-voltage formation method for reducing post-hydration boost time, comprising the following steps:

[0006] S1: sequentially performing first-level formation, second-level formation, third-level formation, fourth-level formation, fifth-level formation and sixth-level formation on the etched foil;

[0007] S2: after the water washing of the six-stage formed formed foil, it is put into a phosphoric acid solution of 40-60℃, treated for 60-180s, water washed, and then put into a 2wt%-10wt% phosphate solution for a second treatment;

[0008] S3: after the second treatment, the aluminum foil is water washed, put into a phosphoric acid solution of 40-60℃, treated for 60-180s, water washed, and then put into a 2wt%-10wt% phosphate solution for a third treatment;

[0009] S4: after the third treatment, the aluminum foil is water washed, put into a phosphoric acid solution of 40-60℃, treated for 60-180s, water washed, and then heat treated at 400-500℃ for 80-180s;

[0010] S5: after the heat treatment, the aluminum foil is put into a 2wt%-10wt% phosphate solution for a fourth treatment, and then dried at 150-250℃ to obtain an anodic aluminum foil;

[0011] Further, the concentration of the phosphoric acid solution in step S2 is 18-25wt%;

[0012] Further, the concentration of the phosphoric acid solution in step S3 is 8-15wt%;

[0013] Further, the concentration of the phosphoric acid solution in step S4 is 3-6wt%.

[0014] Further, the forming solution for the first-stage forming in step S1 is a 1wt%-15wt% ammonium adipate solution, the forming solution for the second-stage forming is a 7wt%-15wt% ammonium adipate solution, the forming solution for the third-stage forming is a 5wt%-15wt% ammonium adipate solution, the forming solution for the fourth-stage forming is a 2wt%-10wt% ammonium adipate solution, the forming solution for the fifth-stage forming is a 2wt%-10wt% ammonium adipate solution, and the forming solution for the sixth-stage forming is a mixed solution of ammonium adipate and phosphate; the temperature of the forming solution is 60-80℃.

[0015] Further, in the mixed solution of ammonium adipate and phosphate, the mass percentage of ammonium adipate is 2wt%-10wt%, and the mass percentage of phosphate is 1wt%-7wt%.

[0016] Further, the time for the first-stage forming in step S1 is 5-10min, and the current density is 0.10-0.30A / dm 2 , the time for the second-stage forming is 5-15min, and the current density is 0.10-0.25A / dm 2 , the time for the third-stage forming is 7-20min, and the current density is 0.10-0.25A / dm 2, the time of the fourth-stage formation is 7-20 min, and the current density is 0.10-0.25 A / dm 2 , the time of the fifth-stage formation is 10-25 min, and the current density is 0.10-0.25 A / dm 2 , the time of the sixth-stage formation is 15-35 min, and the current density is 0.10-0.15 A / dm 2 .

[0017] Further, the voltage of the formation is 20-200 Vf.

[0018] Further, the temperature of the second treatment in step S2 is 70-90 ℃, the time is 5-15 min, the voltage is 20-200 Vf, and the current density is 0.05-0.15 A / dm 2 .

[0019] Further, the temperature of the second treatment in step S2 is 70-90 ℃, the time is 5-15 min, the voltage is 20-200 Vf, and the current density is 0.05-0.15 A / dm 2 .

[0020] Further, the temperature of the second treatment in step S2 is 70-90 ℃, the time is 5-15 min, the voltage is 20-200 Vf, and the current density is 0.05-0.15 A / dm 2 .

[0021] Further, the phosphate solution is one of ammonium dihydrogen phosphate solution, diammonium hydrogen phosphate solution, sodium dihydrogen phosphate solution, disodium hydrogen phosphate solution, potassium dihydrogen phosphate solution, and dipotassium hydrogen phosphate solution. Beneficial effects

[0022] The present application adopts three times of phosphoric acid treatment in the post-treatment part of the original formation process, and controls the concentration of the phosphoric acid solution to be gradiently reduced during the phosphoric acid treatment, so that the obtained aluminum foil has improved capacity and hydration resistance, and the voltage rising time after one hour of hydration treatment is reduced by about 60% compared with the original process, the voltage rising time after six hours of treatment is reduced by about 40% compared with the original process, and the hydration resistance is greatly improved. Specific embodiments

[0023] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with specific embodiments.

[0024] Embodiment 1:

[0025] (1) The etched foil is placed in 15 wt% ammonium adipate solution for first-stage formation treatment, the temperature is 80 ℃, the time is 5 min, the voltage is 20 Vf, and the current density is 0.10 A / dm2 ; after water washing, it is placed in a 10wt% ammonium adipate solution for secondary formation, temperature 80°C, time 5min, voltage 25Vf, current density 0.10A / dm 2 ; after water washing, it is placed in a 5wt% ammonium adipate solution for tertiary formation, temperature 80°C, time 10min, voltage 45Vf, current density 0.25A / dm 2 ; after water washing, it is placed in a 2wt% ammonium adipate solution for quaternary formation, temperature 80°C, time 15min, voltage 85Vf, current density 0.25A / dm 2 ; after water washing, it is placed in a 2wt% ammonium adipate solution for quinary formation, temperature 80°C, time 15min, voltage 95Vf, current density 0.25A / dm 2 ; after water washing, it is placed in a 1wt% ammonium adipate, 1wt% ammonium dihydrogen phosphate solution for sextary formation, temperature 80°C, time 15min, voltage 105Vf, current density 0.15A / dm 2 ;

[0026] (2) after water washing of the sextary formed foil, it is placed in an 18wt% phosphoric acid solution at a temperature of 60°C for 180s, after water washing, it is placed in a 2wt% ammonium dihydrogen phosphate solution for a subsequent treatment, wherein the temperature of the subsequent treatment is 90°C, time 5min, voltage 105Vf, current density 0.15A / dm 2 ;

[0027] (3) after the subsequent treatment, the aluminum foil is water washed and placed in an 8wt% phosphoric acid solution at a temperature of 60°C for 180s, after water washing, it is placed in a 2wt% ammonium dihydrogen phosphate solution for a subsequent second treatment, wherein the temperature of the subsequent second treatment is 90°C, time 5min, voltage 105Vf, current density 0.05A / dm 2 ;

[0028] (4) after the subsequent second treatment, the aluminum foil is water washed and placed in a 3wt% phosphoric acid solution at a temperature of 50°C for 180s, after water washing, it is heat treated at 450°C for 180s;

[0029] (5) after the heat treatment, the aluminum foil is placed in a 2wt% ammonium dihydrogen phosphate solution for a subsequent third treatment, and then dried at 150°C, to obtain an anodic aluminum oxide foil, wherein the temperature of the subsequent third treatment is 90°C, time 5min, voltage 105Vf, current density 0.05A / dm 2 .

[0030] Example 2:

[0031] (1) The etching foil is put into a 15 wt% ammonium adipate solution for primary chemical conversion treatment, at a temperature of 80°C, for 5 minutes, at a voltage of 20 Vf, and at a current density of 0.10 A / dm 2 ; after washing with water, it is put into a 10 wt% ammonium adipate solution for secondary chemical conversion treatment, at a temperature of 80°C, for 5 minutes, at a voltage of 25 Vf, and at a current density of 0.10 A / dm 2 ; after washing with water, it is put into a 5 wt% ammonium adipate solution for tertiary chemical conversion treatment, at a temperature of 80°C, for 10 minutes, at a voltage of 45 Vf, and at a current density of 0.25 A / dm 2 ; after washing with water, it is put into a 2 wt% ammonium adipate solution for quaternary chemical conversion treatment, at a temperature of 80°C, for 15 minutes, at a voltage of 85 Vf, and at a current density of 0.25 A / dm 2 ; after washing with water, it is put into a 2 wt% ammonium adipate solution for quinary chemical conversion treatment, at a temperature of 80°C, for 15 minutes, at a voltage of 95 Vf, and at a current density of 0.25 A / dm 2 ; after washing with water, it is put into a 1 wt% ammonium adipate solution and a 1 wt% ammonium dihydrogen phosphate solution for sexenary chemical conversion treatment, at a temperature of 80°C, for 15 minutes, at a voltage of 105 Vf, and at a current density of 0.15 A / dm 2 ;

[0032] (2) After washing with water, the sexenary-chemically-converted foil is put into a 22 wt% phosphoric acid solution at a temperature of 50°C for 120 seconds, and after washing with water, it is put into a 2 wt% ammonium dihydrogen phosphate solution for a subsequent treatment, wherein the temperature of the subsequent treatment is 90°C, the time is 10 minutes, the voltage is 105 Vf, and the current density is 0.15 A / dm 2 ;

[0033] (3) After washing with water, the foil after the subsequent treatment is put into a 12 wt% phosphoric acid solution at a temperature of 40°C for 120 seconds, and after washing with water, it is put into a 2 wt% ammonium dihydrogen phosphate solution for a second subsequent treatment, wherein the temperature of the second subsequent treatment is 90°C, the time is 5 minutes, the voltage is 105 Vf, and the current density is 0.05 A / dm 2 ;

[0034] (4) After washing with water, the foil after the second subsequent treatment is put into a 5 wt% phosphoric acid solution at a temperature of 50°C for 120 seconds, and after washing with water, it is heat-treated at 450°C for 130 seconds;

[0035] (5) The foil after the heat treatment is put into a 2 wt% ammonium dihydrogen phosphate solution for a third subsequent treatment, and then dried at 200°C to obtain an anodic aluminum oxide foil, wherein the temperature of the third subsequent treatment is 90°C, the time is 8 minutes, the voltage is 105 Vf, and the current density is 0.05 A / dm 2 .

[0036] Example 3:

[0037] (1) The etching foil was subjected to a first-stage chemical conversion treatment in a 15 wt% ammonium adipate solution at a temperature of 80°C for 5 minutes at a voltage of 20 Vf and a current density of 0.10 A / dm 2 ; after washing with water, it was subjected to a second-stage chemical conversion treatment in a 10 wt% ammonium adipate solution at a temperature of 80°C for 5 minutes at a voltage of 25 Vf and a current density of 0.10 A / dm 2 ; after washing with water, it was subjected to a third-stage chemical conversion treatment in a 5 wt% ammonium adipate solution at a temperature of 80°C for 10 minutes at a voltage of 45 Vf and a current density of 0.25 A / dm 2 ; after washing with water, it was subjected to a fourth-stage chemical conversion treatment in a 2 wt% ammonium adipate solution at a temperature of 80°C for 15 minutes at a voltage of 85 Vf and a current density of 0.25 A / dm 2 ; after washing with water, it was subjected to a fifth-stage chemical conversion treatment in a 2 wt% ammonium adipate solution at a temperature of 80°C for 15 minutes at a voltage of 95 Vf and a current density of 0.25 A / dm 2 ; after washing with water, it was subjected to a sixth-stage chemical conversion treatment in a 1 wt% ammonium adipate and 1 wt% ammonium dihydrogen phosphate solution at a temperature of 80°C for 15 minutes at a voltage of 105 Vf and a current density of 0.15 A / dm 2 ;

[0038] (2) After washing with water, the sixth-stage chemical conversion foil was subjected to a first after-treatment in a 20 wt% phosphoric acid solution at a temperature of 45°C for 110 seconds, and after washing with water, it was subjected to a second after-treatment in a 2 wt% ammonium dihydrogen phosphate solution at a temperature of 90°C for 8 minutes at a voltage of 105 Vf and a current density of 0.15 A / dm 2 ;

[0039] (3) After washing with water, the foil after the second after-treatment was subjected to a first after-treatment in a 10 wt% phosphoric acid solution at a temperature of 60°C for 180 seconds, and after washing with water, it was subjected to a second after-treatment in a 2 wt% ammonium dihydrogen phosphate solution at a temperature of 90°C for 15 minutes at a voltage of 105 Vf and a current density of 0.05 A / dm 2 ;

[0040] (4) After washing with water, the foil after the second after-treatment was subjected to a first after-treatment in a 6 wt% phosphoric acid solution at a temperature of 60°C for 130 seconds, and after washing with water, it was subjected to a second after-treatment in a 2 wt% ammonium dihydrogen phosphate solution at a temperature of 90°C for 15 minutes at a voltage of 105 Vf and a current density of 0.05 A / dm

[0041] (5) After washing with water, the foil after the second after-treatment was subjected to a first after-treatment in a 6 wt% phosphoric acid solution at a temperature of 60°C for 130 seconds, and after washing with water, it was subjected to a second after-treatment in a 2 wt% ammonium dihydrogen phosphate solution at a temperature of 90°C for 15 minutes at a voltage of 105 Vf and a current density of 0.05 A / dm2 .

[0042] Example 4:

[0043] (1) The etching foil was subjected to a first-stage chemical conversion treatment in a 15 wt% ammonium adipate solution at a temperature of 80°C for 5 minutes at a voltage of 20 Vf and a current density of 0.10 A / dm 2 ; after washing with water, it was subjected to a second-stage chemical conversion treatment in a 10 wt% ammonium adipate solution at a temperature of 80°C for 5 minutes at a voltage of 25 Vf and a current density of 0.10 A / dm 2 ; after washing with water, it was subjected to a third-stage chemical conversion treatment in a 5 wt% ammonium adipate solution at a temperature of 80°C for 10 minutes at a voltage of 45 Vf and a current density of 0.25 A / dm 2 ; after washing with water, it was subjected to a fourth-stage chemical conversion treatment in a 2 wt% ammonium adipate solution at a temperature of 80°C for 15 minutes at a voltage of 85 Vf and a current density of 0.25 A / dm 2 ; after washing with water, it was subjected to a fifth-stage chemical conversion treatment in a 2 wt% ammonium adipate solution at a temperature of 80°C for 15 minutes at a voltage of 95 Vf and a current density of 0.25 A / dm 2 ; after washing with water, it was subjected to a sixth-stage chemical conversion treatment in a 1 wt% ammonium adipate and 1 wt% ammonium dihydrogen phosphate solution at a temperature of 80°C for 15 minutes at a voltage of 105 Vf and a current density of 0.15 A / dm 2 ;

[0044] (2) After washing the sixth-stage chemical conversion foil, it was subjected to a first after-treatment in a 25 wt% phosphoric acid solution at a temperature of 40°C for 180 seconds, and after washing with water, it was subjected to a second after-treatment in a 2 wt% ammonium dihydrogen phosphate solution at a temperature of 90°C for 15 minutes at a voltage of 105 Vf and a current density of 0.15 A / dm 2 ;

[0045] (3) After washing the second after-treatment foil, it was subjected to a first after-treatment in a 15 wt% phosphoric acid solution at a temperature of 55°C for 160 seconds, and after washing with water, it was subjected to a second after-treatment in a 2 wt% ammonium dihydrogen phosphate solution at a temperature of 90°C for 15 minutes at a voltage of 105 Vf and a current density of 0.05 A / dm 2 ;

[0046] (4) After washing the second after-treatment foil, it was subjected to a first after-treatment in a 6 wt% phosphoric acid solution at a temperature of 40°C for 60 seconds, and after washing with water, it was subjected to a second after-treatment at a temperature of 500°C for 80 seconds;

[0047] (5) The heat-treated aluminum foil is put into a 10wt% ammonium dihydrogen phosphate solution for a post-3rd treatment, and then dried at 250°C to obtain an anodic aluminum foil, wherein the temperature of the post-3rd treatment is 90°C, the time is 5 min, the voltage is 105 Vf, and the current density is 0.05 A / dm 2 .

[0048] Comparative Example 1

[0049] The difference from Example 2 is that only the phosphoric acid treatment in step (2) is performed, and the remaining steps are the same as those in Example 2, and the specific steps are as follows:

[0050] (1) The etched foil is put into a 15wt% ammonium adipate solution for a 1st-stage chemical conversion treatment, the temperature is 80°C, the time is 5 min, the voltage is 20 Vf, and the current density is 0.10 A / dm 2 ; after washing with water, it is put into a 10wt% ammonium adipate solution for a 2nd-stage chemical conversion, the temperature is 80°C, the time is 5 min, the voltage is 25 Vf, and the current density is 0.10 A / dm 2 ; after washing with water, it is put into a 5wt% ammonium adipate solution for a 3rd-stage chemical conversion, the temperature is 80°C, the time is 10 min, the voltage is 45 Vf, and the current density is 0.25 A / dm 2 ; after washing with water, it is put into a 2wt% ammonium adipate solution for a 4th-stage chemical conversion, the temperature is 80°C, the time is 15 min, the voltage is 85 Vf, and the current density is 0.25 A / dm 2 ; after washing with water, it is put into a 2wt% ammonium adipate solution for a 5th-stage chemical conversion, the temperature is 80°C, the time is 15 min, the voltage is 95 Vf, and the current density is 0.25 A / dm 2 ; after washing with water, it is put into a 1wt% ammonium adipate solution and a 1wt% ammonium dihydrogen phosphate solution for a 6th-stage chemical conversion, the temperature is 80°C, the time is 15 min, the voltage is 105 Vf, and the current density is 0.15 A / dm 2 ;

[0051] (2) The 6th-stage chemical conversion foil is washed with water and then put into a 22wt% phosphoric acid solution at a temperature of 50°C for a treatment of 120 s, and after washing with water, it is put into a 2wt% ammonium dihydrogen phosphate solution for a post-1st treatment, wherein the temperature of the post-1st treatment is 90°C, the time is 10 min, the voltage is 105 Vf, and the current density is 0.15 A / dm 2 ;

[0052] (3) The aluminum foil after the post-1st treatment is washed with water and then put into a 2wt% ammonium dihydrogen phosphate solution for a post-2nd treatment, wherein the temperature of the post-2nd treatment is 90°C, the time is 5 min, the voltage is 105 Vf, and the current density is 0.05 A / dm 2 ;

[0053] (4) The aluminum foil after the last two treatments is washed with water and then heat treated at 450°C for 130s;

[0054] (5) The aluminum foil after the heat treatment is put into a 2wt% ammonium dihydrogen phosphate solution for the last three treatments, and then dried at 200°C to obtain an anodic aluminum foil, wherein the temperature of the last three treatments is 90°C, the time is 8min, the voltage is 105Vf, and the current density is 0.05A / dm 2 .

[0055] Comparative Example 2:

[0056] The difference from Example 2 is that the phosphoric acid treatment in step (4) is not performed, and the remaining steps are the same as those in Example 2, and the specific steps are as follows:

[0057] (1) The etched foil is put into a 15wt% ammonium adipate solution for primary chemical conversion treatment, the temperature is 80°C, the time is 5min, the voltage is 20Vf, and the current density is 0.10A / dm 2 ; After washing with water, it is put into a 10wt% ammonium adipate solution for secondary chemical conversion, the temperature is 80°C, the time is 5min, the voltage is 25Vf, and the current density is 0.10A / dm 2 ; After washing with water, it is put into a 5wt% ammonium adipate solution for tertiary chemical conversion, the temperature is 80°C, the time is 10min, the voltage is 45Vf, and the current density is 0.25A / dm 2 ; After washing with water, it is put into a 2wt% ammonium adipate solution for quaternary chemical conversion, the temperature is 80°C, the time is 15min, the voltage is 85Vf, and the current density is 0.25A / dm 2 ; After washing with water, it is put into a 2wt% ammonium adipate solution for quinary chemical conversion, the temperature is 80°C, the time is 15min, the voltage is 95Vf, and the current density is 0.25A / dm 2 ; After washing with water, it is put into a 1wt% ammonium adipate and 1wt% ammonium dihydrogen phosphate solution for sextenary chemical conversion, the temperature is 80°C, the time is 15min, the voltage is 105Vf, and the current density is 0.15A / dm 2 ;

[0058] (2) The chemical conversion foil after the sextenary chemical conversion is washed with water and then put into a 22wt% phosphoric acid solution at a temperature of 50°C for 120s, and then washed with water, and then put into a 2wt% ammonium dihydrogen phosphate solution for the last treatment, wherein the temperature of the last treatment is 90°C, the time is 10min, the voltage is 105Vf, and the current density is 0.15A / dm 2 ;

[0059] (3) the aluminum foil after the second treatment is washed with water and then placed in a 12 wt% phosphoric acid solution at 40°C for 120 s, washed with water again, and then placed in a 2 wt% ammonium dihydrogen phosphate solution for a third treatment, wherein the temperature of the third treatment is 90°C, the time is 5 min, the voltage is 105 Vf, and the current density is 0.05 A / dm 2 ;

[0060] (4) the aluminum foil after the third treatment is washed with water and then heat treated at 450°C for 130 s;

[0061] (5) the aluminum foil after the heat treatment is placed in a 2 wt% ammonium dihydrogen phosphate solution for a fourth treatment, and then dried at 200°C to obtain an anodic aluminum foil, wherein the temperature of the fourth treatment is 90°C, the time is 8 min, the voltage is 105 Vf, and the current density is 0.05 A / dm 2 .

[0062] Comparative Example 3

[0063] The difference from Example 2 is that the concentration of the phosphoric acid solution is 10 wt% in each phosphoric acid treatment, and the other steps are the same as those in Example 2, and the specific steps are as follows:

[0064] (1) the etched foil is placed in a 15 wt% ammonium adipate solution for a first-stage chemical conversion treatment at a temperature of 80°C for 5 min, a voltage of 20 Vf, and a current density of 0.10 A / dm 2 ; after washing with water, it is placed in a 10 wt% ammonium adipate solution for a second-stage chemical conversion treatment at a temperature of 80°C for 5 min, a voltage of 25 Vf, and a current density of 0.10 A / dm 2 ; after washing with water, it is placed in a 5 wt% ammonium adipate solution for a third-stage chemical conversion treatment at a temperature of 80°C for 10 min, a voltage of 45 Vf, and a current density of 0.25 A / dm 2 ; after washing with water, it is placed in a 2 wt% ammonium adipate solution for a fourth-stage chemical conversion treatment at a temperature of 80°C for 15 min, a voltage of 85 Vf, and a current density of 0.25 A / dm 2 ; after washing with water, it is placed in a 2 wt% ammonium adipate solution for a fifth-stage chemical conversion treatment at a temperature of 80°C for 15 min, a voltage of 95 Vf, and a current density of 0.25 A / dm 2 ; after washing with water, it is placed in a 1 wt% ammonium adipate and 1 wt% ammonium dihydrogen phosphate solution for a sixth-stage chemical conversion treatment at a temperature of 80°C for 15 min, a voltage of 105 Vf, and a current density of 0.15 A / dm 2 ;

[0065] (2) the formed foil after formation is placed in a 10wt% phosphoric acid solution with a temperature of 50°C for 120s, and after washing, it is placed in a 2wt% ammonium dihydrogen phosphate solution for a second treatment, wherein the temperature of the second treatment is 90°C, the time is 10min, the voltage is 105Vf, and the current density is 0.15A / dm2;

[0066] (3) the foil after the second treatment is washed and placed in a 10wt% phosphoric acid solution with a temperature of 40°C for 120s, and after washing, it is placed in a 2wt% ammonium dihydrogen phosphate solution for a third treatment, wherein the temperature of the third treatment is 90°C, the time is 5min, the voltage is 105Vf, and the current density is 0.05A / dm2;

[0067] (4) the foil after the third treatment is washed and placed in a 10wt% phosphoric acid solution with a temperature of 50°C for 120s, and after washing, it is heat treated at 450°C for 130s;

[0068] (5) the foil after the heat treatment is placed in a 2wt% ammonium dihydrogen phosphate solution for a fourth treatment, and then dried at 200°C to obtain an anodic aluminum foil, wherein the temperature of the fourth treatment is 90°C, the time is 8min, the voltage is 105Vf, and the current density is 0.05A / dm 2 .

[0069] Performance test

[0070] Specific capacity: according to the standard method of EIAJ RC-2364A, a specific capacity tester is used for measurement, and the test results are shown in Table 1.

[0071] Hydration resistance: the samples obtained in the examples and the comparative examples are incubated in pure water at 100°C for 12h, and the voltage rising time and the reaching voltage are measured according to the Tr / Vt test method, and the measurement results are shown in Table 1.

[0072] Table 1 Performance test results

[0073]

[0074] Data analysis, as can be seen from Table 1, the anodic aluminum foil obtained by the low-voltage formation method for reducing the hydration voltage rising time of the present application is in a relatively excellent level in terms of voltage resistance value and specific capacity at 105V, and its hydration resistance is excellent, and the voltage rising time is relatively short after 1h and 6h of hydration treatment.

[0075] It can be seen from Example 2 and Comparative Examples 1-3 that the present application can improve the capacity and hydration resistance of the final aluminum foil by using three times of phosphoric acid treatment in the post-treatment part of the original chemical conversion process and controlling the concentration of the phosphoric acid solution to be gradiently reduced during the phosphoric acid treatment. This is likely because the aluminum foil treated by the method of the present application generates a more compact aluminum oxide film on the surface, reduces the number of micropores in the oxide layer, and reduces the penetration of water.

[0076] It should be understood by those of ordinary skill in the art that the above discussion of any of the embodiments is merely exemplary and is not intended to suggest the scope of the present application is limited to these examples; the above embodiments or technical features among different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of the different aspects of the present application as described above. In order to be brief, they are not provided in detail.

Claims

1. A low pressure formation method for reducing the pressurization time after hydration, characterized by, The method comprises the following steps: S1: sequentially performing first-stage chemical conversion, second-stage chemical conversion, third-stage chemical conversion, fourth-stage chemical conversion, fifth-stage chemical conversion and sixth-stage chemical conversion on the etching foil; S2: after the sixth-stage chemical conversion, washing the chemical conversion foil, and then placing the chemical conversion foil in a 40-60℃ phosphoric acid solution for 60-180s, and then washing the chemical conversion foil, and then placing the chemical conversion foil in a 2wt%-10wt% phosphate solution for a second-stage post-treatment; S3: after the second-stage post-treatment, washing the aluminum foil, and then placing the aluminum foil in a 40-60℃ phosphoric acid solution for 60-180s, and then washing the aluminum foil, and then placing the aluminum foil in a 2wt%-10wt% phosphate solution for a third-stage post-treatment; S4: after the third-stage post-treatment, washing the aluminum foil, and then placing the aluminum foil in a 40-60℃ phosphoric acid solution for 60-180s, and then washing the aluminum foil, and then placing the aluminum foil in a 400-500℃ phosphoric acid solution for 80-180s; S5: after the heat treatment, placing the aluminum foil in a 2wt%-10wt% phosphate solution for a fourth-stage post-treatment, and then drying the aluminum foil at 150-250℃ to obtain an anodic aluminum foil; The concentration of the phosphoric acid solution in step S2 is 18-25wt%, the concentration of the phosphoric acid solution in step S3 is 8-15wt%, and the concentration of the phosphoric acid solution in step S4 is 3-6wt%.

2. The low-pressure formation method for reducing the pressurization time after hydration according to claim 1, characterized by, The chemical conversion solution for the first-stage chemical conversion in step S1 is a 1wt%-15wt% ammonium adipate solution, the chemical conversion solution for the second-stage chemical conversion is a 7wt%-15wt% ammonium adipate solution, the chemical conversion solution for the third-stage chemical conversion is a 5wt%-15wt% ammonium adipate solution, the chemical conversion solution for the fourth-stage chemical conversion is a 2wt%-10wt% ammonium adipate solution, the chemical conversion solution for the fifth-stage chemical conversion is a 2wt%-10wt% ammonium adipate solution, and the chemical conversion solution for the sixth-stage chemical conversion is a mixed solution of ammonium adipate and a phosphate.

3. The low-pressure formation method for reducing the pressurization time after hydration according to claim 2, characterized by, In the mixed solution of ammonium adipate and a phosphate, the mass percentage of ammonium adipate is 2wt%-10wt%, and the mass percentage of the phosphate is 1wt%-7wt%.

4. The low-pressure formation method for reducing the pressurization time after hydration according to claim 1, characterized by, The time for the first-stage formation in step S1 is 5-10 min, and the current density is 0.10-0.30 A / dm 2 The time for the second-stage formation is 5-15 min, and the current density is 0.10-0.25 A / dm 2 The time for the third-stage formation is 7-20 min, and the current density is 0.10-0.25 A / dm 2 The time for the fourth-stage formation is 7-20 min, and the current density is 0.10-0.25 A / dm 2 The time for the fifth-stage formation is 10-25 min, and the current density is 0.10-0.25 A / dm 2 The time for the sixth-stage formation is 15-35 min, and the current density is 0.10-0.15 A / dm 2 .

5. The low pressure formation method of reducing the pressurization time after hydration according to claim 1, characterized by, The voltage of the chemical conversion is 20-200Vf.

6. The low-pressure formation method of reducing the pressurization time after hydration according to claim 1, characterized by, The temperature of the latter treatment in step S2 is 70-90°C, the time is 5-15 min, the voltage is 20-200 Vf, and the current density is 0.05-0.15 A / dm 2 .

7. The low-pressure formation method of reducing the pressurization time after hydration according to claim 1, characterized by, The temperature of the post-treatment in step S3 is 70-90°C, the time is 5-15 min, the voltage is 20-200 Vf, and the current density is 0.05-0.15 A / dm 2 .

8. The low-pressure formation method of reducing the pressurization time after hydration according to claim 1, characterized by, The temperature of the last three processes in step S5 is 70-90°C, the time is 5-10 min, the voltage is 20-200 Vf, and the current density is 0.05-0.15 A / dm 2 .

9. The low pressure formation method of reducing the post-hydration pressurization time according to claim 1, characterized by, The phosphate solution is one of ammonium dihydrogen phosphate solution, diammonium hydrogen phosphate solution, sodium dihydrogen phosphate solution, disodium hydrogen phosphate solution, potassium dihydrogen phosphate solution and dipotassium hydrogen phosphate solution.

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