A method for testing the lead sulfate content in the positive plate of a lead-acid battery after formation.

Abstract

This invention relates to the field of lead-acid battery technology and discloses a method for testing the lead sulfate content in the positive electrode plate of a lead-acid battery after formation. The method includes four steps: pretreatment, releasing lead sulfate encapsulated by impurities, salt leaching, and EDTA titration of lead sulfate. This method has small errors, provides accurate and reliable test results, and is simple to operate. The second step releases all the lead sulfate encapsulated by impurities, ensuring that the lead sulfate content in subsequent titration is consistent with the actual lead sulfate content. The third step eliminates the problem that some lead oxide impurities dissolve into lead ions when lead sulfate is converted into soluble lead ions, ensuring the accuracy and reliability of lead sulfate detection.

Description

Technical Field

[0001] This invention belongs to the field of lead-acid battery technology, and in particular relates to a method for testing the lead sulfate content in the positive electrode plate of a lead-acid battery after formation. Background Technology

[0002] Lead-acid battery formation is an indispensable process in lead-acid battery production. The main components of the raw plates initially produced in lead-acid battery production include: monobasic lead sulfate (1BS, PbO·PbSO4), tribasic lead sulfate (3BS, 3PbO·PbSO4), tetrabasic lead sulfate (4BS, 4PbO·PbSO4), and lead sulfate (PbSO4). After the raw plates are assembled into a lead-acid battery, they need to be formed. The formation process is the process of the first charge of the lead-acid battery. Through formation, the active material on the positive plate is electrochemically oxidized into lead dioxide, while an electrochemical reduction reaction occurs on the negative plate to generate spongy lead. Therefore, the change in the lead sulfate content on the positive plate after formation can directly reflect the degree of lead sulfate conversion into active material during the charging process, and thus directly reflect the impact of the formation process on the performance of the lead-acid battery.

[0003] Currently, no method for testing the lead sulfate content in the positive plate of a lead-acid battery after formation is disclosed in existing technologies. Therefore, providing a method for testing the lead sulfate content in the positive plate of a lead-acid battery after formation is of great significance for studying the impact of the formation process on lead-acid batteries. Among the currently disclosed methods, there are many methods for detecting the lead sulfate content in other components of lead-acid batteries, such as the method for testing lead sulfate in the separator paper of a lead-acid battery disclosed in publication number CN109060785A and the method for determining the lead sulfate content in battery lead paste disclosed in publication number CN113390751A. Currently, the commonly used method for detecting lead ion content is EDTA titration. This invention finds that directly using EDTA titration to determine the lead sulfate content in the positive plate after formation results in a large error between the detected and actual results. Therefore, it is necessary to improve upon this method to obtain a method that can accurately detect the lead sulfate content in the positive plate after formation. Summary of the Invention

[0004] To overcome the problem of large discrepancies between the measured and actual results when directly using EDTA titration to determine the lead sulfate content in the positive electrode plate after formation of a lead-acid battery, this invention provides a method for testing the lead sulfate content in the positive electrode plate after formation. This method provides accurate and reliable test results and is simple to operate. It eliminates the problems of inaccurate test results caused by lead oxides encapsulating lead sulfate and the dissolution of small amounts of lead oxides during the dissolution of lead sulfate, thus minimizing the error between the measured lead sulfate content and the actual lead sulfate content on the positive electrode plate and resulting in more accurate test results.

[0005] The specific technical solution of this invention is as follows:

[0006] A method for testing the lead sulfate content in the positive electrode plate of a lead-acid battery after formation, characterized by comprising the following steps:

[0007] Step 1: Clean and sample the formed positive electrode plate sequentially to obtain a pretreated sample;

[0008] Step 2: Weigh a pretreated sample of mass M as the test sample, place the test sample in a container and add nitric acid and hydrogen peroxide to obtain the first mixture, and perform the first filtration treatment on the first mixture to recover the pure filter residue for later use;

[0009] Step 3: Place the pure filter residue in a container, add sodium chloride solution, stir, and let stand to obtain the second mixture. After the second mixture is subjected to a second filtration process, the second filtrate is obtained. The second filtrate is then diluted to a fixed volume to obtain the salt-leached lead sample.

[0010] Step 4: Take a portion of the salt-immersed lead sample as the test sample, titrate the test sample using the lead ion EDTA titration method, and record the volume of EDTA standard solution consumed in the titration as V;

[0011] Step 5: Calculate the lead sulfate content in the positive electrode plate after formation. The calculation formula is:

[0012] Where C is the concentration of the EDTA standard solution in mol / L; V is the volume of the EDTA standard solution used in mL; 303.26 is the molar mass of lead sulfate in g / mol; 10 is the mass conversion factor; and M is the sample mass in g.

[0013] This invention provides a method for testing the lead sulfate content in the positive electrode plate of a lead-acid battery after formation. The method includes five steps: First, the positive electrode plate is cleaned to remove the electrolyte. After cleaning, a sample is taken from the positive electrode plate for lead sulfate content testing. Second, a pretreated sample is quantitatively weighed as the test sample. Nitric acid and hydrogen peroxide are added to the test sample to prepare a first mixture. The first mixture is then filtered and the residue is washed to obtain a pure residue. In practical operation, it was found that some lead sulfate is coated with impurities such as lead oxides. Directly using titration for detection will lead to these coated impurities being trapped. Since lead sulfate encapsulated in lead sulfate cannot be detected, this invention adds a second treatment step before titration. This second treatment removes all lead oxides and other organic matter from the sample, minimizing impurities in the remaining lead sulfate residue. It also releases any lead sulfate encapsulated by impurities, ensuring the lead sulfate content in subsequent titration matches the actual lead sulfate content. The third step involves adding the purified residue to a sodium chloride solution to obtain a salt-leached lead sample. The fourth step uses EDTA titration to titrate the salt-leached lead sample. The fifth step calculates the lead sulfate content using the formula described above. Because lead sulfate is... Lead sulfate is insoluble in water, so when using titration to detect lead sulfate, it is necessary to first convert the lead sulfate into soluble lead ions. Currently, the common method is to heat lead sulfate with ammonium acetate to boiling, converting the lead sulfate into soluble lead acetate. However, this invention has found that a small amount of lead oxide is not completely removed during the pretreatment of lead sulfate. During the subsequent conversion of lead sulfate to lead acetate, this unremoved lead oxide will also be converted into lead acetate. This impurity will affect the actual lead sulfate content, making the detection results inaccurate. Therefore, to address the above problem, this invention adds a third step: lead sulfate in sodium chloride... Lead ions can dissolve in solution, and the amount of lead sulfate dissolved under certain conditions is constant. Therefore, this invention utilizes this phenomenon to place lead sulfate in a sodium chloride solution and, under certain conditions, dissolve the lead ions in the lead sulfate to prepare a salt-leached lead sample. The mass of the lead sulfate residue is calculated by calculating the amount of substance dissolved by lead sulfate in sodium chloride. The third step of processing avoids the problem of a small amount of lead oxide dissolving when converting lead sulfate to lead acetate, which could lead to inaccurate measurement data. The above method provides more accurate and reliable test data and is simple to operate when measuring the lead sulfate content in the positive electrode plate after formation.

[0014] Preferably, the cleaning process in step 1 includes: washing the positive electrode plate with pure water until the pH is 6-7, and then drying and cooling it for later use.

[0015] As a preferred embodiment, the sampling process in step 1 includes: randomly selecting multiple grid units on the grid of the formed positive electrode plate, separating, collecting, and grinding the active material within the grid unit range for later use; the above sampling method adopts a random multi-point sampling method to ensure the consistency between the sampled sample and the real sample.

[0016] Preferably, the first mixture in step 2 includes a first state and a second state. The first state is when the first mixture produces microbubbles, and the second state is when the second mixture does not produce microbubbles. The first mixture is filtered when it enters the second state. When nitric acid and hydrogen peroxide are added to the sample to be tested, hydrogen peroxide can react with the additives to produce bubbles. Therefore, the presence or absence of bubbles can be used to determine whether the impurities have been cleaned.

[0017] Preferably, the mass fraction of sodium chloride in step 3 is 25-26%, and the standing time is 8-16 hours.

[0018] In practical operation, this invention found that when sodium chloride is used to dissolve lead sulfate, the concentration of sodium chloride and the standing time have a significant impact on the test results. When the mass fraction of sodium chloride is in the range of 25-26% and the standing time is 8-16 hours, the dissolution effect of lead sulfate is the best, the test results are closest to the actual results, and the data are the most authentic.

[0019] Preferably, the preparation of the first mixture is carried out using a vibration device, which includes an oscillator and an ultrasonic cleaner; the vibration device can accelerate the impurity removal process, enabling the impurities wrapped around the lead sulfate to disintegrate rapidly and speeding up the impurity removal effect.

[0020] Preferably, the first filtration process includes: placing quantitative filter paper on a funnel, wetting the quantitative filter paper with glacial acetic acid, filtering and separating the second mixture using the quantitative filter paper to obtain filtrate and filter residue, and washing the filter residue with sodium chloride washing solution and acetic acid ethanol washing solution to obtain pure filter residue.

[0021] Preferably, the second filtration step includes: separating the second mixture using quantitative filter paper to obtain a second filtrate and a second filter residue, and rinsing the second filter residue with sodium chloride washing solution until the second filter residue is free of lead ions.

[0022] Preferably, the steps of the lead ion EDTA titration method include: diluting the test sample and adjusting the pH to 5-6, then adding hexamethylenetetramine solution, ascorbic acid, and dimethylphenol orange indicator to prepare a titrant solution; titrating the titrant solution with EDTA standard solution; stopping the titration after the solution turns bright yellow; and recording the amount of EDTA standard solution used in the titration.

[0023] Compared with the prior art, the present invention has the following technical effects:

[0024] (1) The present invention provides a test method for the lead sulfate content in the positive plate after the formation of lead-acid batteries with small error, accurate test results and simple operation;

[0025] (2) The method provided by the present invention releases all the lead sulfate that is wrapped by impurities through the second step of the process, ensuring that the content of lead sulfate in the subsequent titration test is consistent with the actual content of lead sulfate.

[0026] (3) The method provided by the present invention can eliminate the problem that some lead oxide impurities will also dissolve into lead ions when lead sulfate is converted into soluble lead ions through the third step of processing, thus ensuring the authenticity and accuracy of lead sulfate detection. Detailed Implementation

[0027] The present invention will be further described below with reference to embodiments.

[0028] Example 1:

[0029] A method for testing the lead sulfate content in the positive plate of a lead-acid battery after formation, comprising the following steps:

[0030] Step 1: After formation, the positive electrode plate is cleaned and sampled sequentially to obtain a pretreated sample. Cleaning: The positive electrode plate is washed with pure water until the pH of the sample surface is 7. It is then transferred to a 55°C forced-air drying oven to dry to constant weight. After drying, it is taken out and cooled to room temperature. Sampling: At least 5 individual samples are taken from the middle and lower part of the positive electrode plate using a sampling cone. The samples are then ground in a mortar to make pretreated sample powder and placed in a weighing bottle for testing.

[0031] Step 2: Weigh a pretreated sample of mass M (M is 2g, accurate to 0.001g) as the test sample. Place the test sample in an Erlenmeyer flask and add 15mL of nitric acid (mass ratio of nitric acid to water is 1:1) and 18mL of hydrogen peroxide (mass ratio of hydrogen peroxide to water is 1:20). Use a shaker to slowly vibrate for 25min to obtain the first mixture. The first mixture includes a first state and a second state. The first state is when the first mixture produces microbubbles, and the second state is when there are no microbubbles in the second mixture. When the first mixture enters the second state, it is filtered. The first mixture is subjected to the first filtration treatment to recover the pure filter residue for later use. The first filtration treatment is as follows: filter the first mixture using rapid quantitative filter paper, and wash the filter residue with 80mL of acetic acid ethanol washing solution to obtain pure residue.

[0032] Step 3: Place the pure filter residue in a beaker, add 100 ml of sodium chloride (25% by mass) solution, stir, and let stand for 8 hours to obtain the second mixture. After the second mixture is subjected to a second filtration treatment, the second filtrate is obtained. The second filtrate is then diluted to volume to obtain the salt-impregnated lead sample. Second filtration treatment: Filter the second mixture using rapid quantitative filter paper. Before filtration, moisten the filter paper with 5 ml of glacial acetic acid. Filter the filtrate into a 250 mL volumetric flask, wash the beaker residue with 80 mL of sodium chloride washing solution (10% by mass), add pure water to volume and shake well to obtain the salt-impregnated lead sample.

[0033] Step 4: Take a portion of the salt-immersed lead sample as the test sample. Titrate the test sample using the lead ion EDTA titration method and record the volume of EDTA standard solution consumed in the titration as V. The steps of the lead ion EDTA titration method are as follows: Use a pipette to transfer 25 mL of salt-immersed lead into a 250 mL Erlenmeyer flask, dilute with water to 100 mL, adjust the pH of the solution to 5 to 6 using ammonia water (mass ratio of 1:1), add 5 mL of hexamethylenetetramine solution (mass fraction of 10%), 3 mL of saturated thiourea solution, 0.1 g of ascorbic acid, and 1 to 3 drops of xylenol orange indicator, and titrate with EDTA standard solution (EDTA concentration of 0.02 mol / L) until a bright yellow color is obtained.

[0034] Step 5: Calculate the lead sulfate content in the positive electrode plate after formation. The calculation formula is as follows: Where C is the concentration of the EDTA standard solution in mol / L; V is the volume of the EDTA standard solution used in mL; 303.26 is the molar mass of lead sulfate in g / mol; 10 is the mass conversion factor; and M is the sample mass in g.

[0035] Example 2:

[0036] A method for testing the lead sulfate content in the positive plate of a lead-acid battery after formation, comprising the following steps:

[0037] Step 1: After formation, the positive electrode plate is cleaned and sampled sequentially to obtain a pretreated sample. Cleaning: The positive electrode plate is washed with pure water until the pH of the sample surface is 7. It is then transferred to a 55°C forced-air drying oven to dry to constant weight. After drying, it is taken out and cooled to room temperature. Sampling: At least 5 individual samples are taken from the middle and lower part of the positive electrode plate using a sampling cone. The samples are then ground in a mortar to make pretreated sample powder and placed in a weighing bottle for testing.

[0038] Step 2: Weigh a pretreated sample of mass M (M is 2g, accurate to 0.001g) as the test sample. Place the test sample in an Erlenmeyer flask and add 15mL of nitric acid (mass ratio of nitric acid to water is 1:1) and 18mL of hydrogen peroxide (mass ratio of hydrogen peroxide to water is 1:20). Use a shaker to slowly vibrate for 25min to obtain the first mixture. The first mixture includes a first state and a second state. The first state is when the first mixture produces microbubbles, and the second state is when there are no microbubbles in the second mixture. When the first mixture enters the second state, it is filtered. The first mixture is subjected to the first filtration treatment to recover the pure filter residue for later use. The first filtration treatment is as follows: filter the first mixture using rapid quantitative filter paper, and wash the filter residue with 80mL of acetic acid ethanol washing solution to obtain pure residue.

[0039] Step 3: Place the pure filter residue in a beaker, add 100 ml of sodium chloride (25.5% by mass) solution, stir, and let stand for 10 h to obtain the second mixture. After the second mixture is subjected to a second filtration treatment, the second filtrate is obtained. The second filtrate is then diluted to volume to obtain the salt-impregnated lead sample. Second filtration treatment: Filter the second mixture using rapid quantitative filter paper. Before filtration, wet the filter paper with 5 ml of glacial acetic acid. Filter the filtrate into a 250 mL volumetric flask, wash the beaker residue with 80 mL of sodium chloride washing solution (10% by mass), add pure water to volume and shake well to obtain the salt-impregnated lead sample.

[0040] Step 4: Take a portion of the salt-immersed lead sample as the test sample. Titrate the test sample using the lead ion EDTA titration method and record the volume of EDTA standard solution consumed in the titration as V. The steps of the lead ion EDTA titration method are as follows: Use a pipette to transfer 25 mL of salt-immersed lead into a 250 mL Erlenmeyer flask, dilute with water to 100 mL, adjust the pH of the solution to 5 to 6 using ammonia water (mass ratio of 1:1), add 5 mL of hexamethylenetetramine solution (mass fraction of 10%), 3 mL of saturated thiourea solution, 0.1 g of ascorbic acid, and 1 to 3 drops of xylenol orange indicator, and titrate with EDTA standard solution (EDTA concentration of 0.02 mol / L) until a bright yellow color is obtained.

[0041] Step 5: Calculate the lead sulfate content in the positive electrode plate after formation. The calculation formula is as follows: Where C is the concentration of the EDTA standard solution in mol / L; V is the volume of the EDTA standard solution used in mL; 303.26 is the molar mass of lead sulfate in g / mol; 10 is the mass conversion factor; and M is the sample mass in g.

[0042] Example 3:

[0043] A method for testing the lead sulfate content in the positive plate of a lead-acid battery after formation, comprising the following steps:

[0044] Step 1: After formation, the positive electrode plate is cleaned and sampled sequentially to obtain a pretreated sample. Cleaning: The positive electrode plate is washed with pure water until the pH of the sample surface is 7. It is then transferred to a 55°C forced-air drying oven to dry to constant weight. After drying, it is taken out and cooled to room temperature. Sampling: At least 5 individual samples are taken from the middle and lower part of the positive electrode plate using a sampling cone. The samples are then ground in a mortar to make pretreated sample powder and placed in a weighing bottle for testing.

[0045] Step 2: Weigh a pretreated sample of mass M (M is 2g, accurate to 0.001g) as the test sample. Place the test sample in an Erlenmeyer flask and add 15mL of nitric acid (mass ratio of nitric acid to water is 1:1) and 18mL of hydrogen peroxide (mass ratio of hydrogen peroxide to water is 1:20). Use a shaker to slowly vibrate for 25min to obtain the first mixture. The first mixture includes a first state and a second state. The first state is when the first mixture produces microbubbles, and the second state is when there are no microbubbles in the second mixture. When the first mixture enters the second state, it is filtered. The first mixture is subjected to the first filtration treatment to recover the pure filter residue for later use. The first filtration treatment is as follows: filter the first mixture using rapid quantitative filter paper, and wash the filter residue with 80mL of acetic acid ethanol washing solution to obtain pure residue.

[0046] Step 3: Place the pure filter residue in a beaker, add 100 ml of sodium chloride (26% by mass) solution, stir, and let stand for 16 hours to obtain the second mixture. After the second mixture is subjected to a second filtration treatment, the second filtrate is obtained. The second filtrate is then diluted to volume to obtain the salt-impregnated lead sample. Second filtration treatment: Filter the second mixture using rapid quantitative filter paper. Before filtration, moisten the filter paper with 5 ml of glacial acetic acid. Filter the filtrate into a 250 mL volumetric flask, wash the beaker residue with 80 mL of sodium chloride washing solution (10% by mass), add pure water to volume and shake well to obtain the salt-impregnated lead sample.

[0047] Step 4: Take a portion of the salt-immersed lead sample as the test sample. Titrate the test sample using the lead ion EDTA titration method and record the volume of EDTA standard solution consumed in the titration as V. The steps of the lead ion EDTA titration method are as follows: Use a pipette to transfer 25 mL of salt-immersed lead into a 250 mL Erlenmeyer flask, dilute with water to 100 mL, adjust the pH of the solution to 5 to 6 using ammonia water (mass ratio of 1:1), add 5 mL of hexamethylenetetramine solution (mass fraction of 10%), 3 mL of saturated thiourea solution, 0.1 g of ascorbic acid, and 1 to 3 drops of xylenol orange indicator, and titrate with EDTA standard solution (EDTA concentration of 0.02 mol / L) until a bright yellow color is obtained.

[0048] Step 5: Calculate the lead sulfate content in the positive electrode plate after formation. The calculation formula is as follows: Where C is the concentration of the EDTA standard solution in mol / L; V is the volume of the EDTA standard solution used in mL; 303.26 is the molar mass of lead sulfate in g / mol; 10 is the mass conversion factor; and M is the sample mass in g.

[0049] Comparative Example 1: (The influence of impurities encapsulating lead sulfate and lead-containing impurities was not excluded)

[0050] Compared with Example 1, Comparative Example 1 did not perform the second and third steps, and the remaining conditions were the same as in Example 1.

[0051] Comparative Example 2: (The influence of lead sulfate encapsulated by impurities was not excluded)

[0052] Compared with Example 1, the second step was not performed in Comparative Example 2, and the other conditions were the same as in Example 1.

[0053] Comparative Example 3: (The influence of lead impurities was not excluded)

[0054] Compared with Example 1, the third step was not performed in Comparative Example 3, and the other conditions were the same as in Example 1.

[0055] Comparative Example 4: (The mass fraction of sodium chloride is too small)

[0056] Compared with Example 1, the mass fraction of sodium chloride in Comparative Example 4 was 20%, and all other conditions were the same as in Example 1.

[0057] Comparative Example 5: (Insufficient settling time)

[0058] Compared with Example 1, the standing time in Comparative Example 5 was 4 hours, and all other conditions were the same as in Example 1.

[0059] Comparative Example 6: (Excessive standing time)

[0060] Compared with Example 1, the standing time in Comparative Example 6 was 20 hours, and all other conditions were the same as in Example 1.

[0061] Detection example

[0062] The detection results and detection accuracy of Examples 1-3 and Comparative Examples 1-6 were tested. The accuracy test used XRD semi-quantitative detection to determine the lead sulfate content. The test results are shown in Table 1.

[0063] Table 1 Test Results

[0064]

[0065] As shown in Table 1, the lead sulfate content measured in Examples 1-3 was not significantly different from the lead sulfate content obtained in actual testing, and the test results were accurate and true. In Comparative Examples 1 and 2, lead sulfate was not coated with impurities that were not removed, and the lead sulfate content obtained in Comparative Examples 1 and 2 was significantly lower than the lead sulfate content obtained in actual testing. In Comparative Example 3, the lead sulfate content obtained in the test results was significantly higher than the lead sulfate content obtained in actual testing due to the influence of lead impurities.

[0066] In addition, the concentration of sodium chloride and the settling time have a significant impact on the test results. In Comparative Example 4, the concentration of sodium chloride used was too low, and the lead sulfate content obtained in Comparative Example 4 was significantly lower than the actual lead sulfate content obtained in the test. In Comparative Example 5, the settling time was too short, and the lead sulfate content obtained in Comparative Example 5 was significantly lower than the actual lead sulfate content obtained in the test. In Comparative Example 6, the settling time was too long, and the lead sulfate content obtained in Comparative Example 6 was not significantly different from the lead sulfate content obtained in the actual XRD test. This indicates that the test results did not change after the settling time exceeded 8 hours.

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for testing the lead sulfate content in the positive plate of a lead-acid battery after formation, characterized in that, Includes the following steps: Step 1: Clean and sample the formed positive electrode plate sequentially to obtain a pretreated sample; Step 2: Weigh out a sample with a mass of [mass value missing]. M The pretreated sample is the test sample. The test sample is placed in a container and nitric acid and hydrogen peroxide are added to obtain the first mixture. The first mixture is subjected to the first filtration treatment to recover the pure filter residue for later use. Step 3: Place the pure filter residue in a container, add sodium chloride solution, stir, and let stand to obtain the second mixture. After the second mixture is subjected to a second filtration process, the second filtrate is obtained. The second filtrate is then diluted to a fixed volume to obtain the salt-leached lead sample. Step 4: Take a portion of the salt-immersed lead sample as the test sample, and titrate the test sample using the lead ion EDTA titration method. Record the volume of EDTA standard solution consumed in the titration. V ; Step 5: Calculate the lead sulfate content in the positive electrode plate after formation. The calculation formula is: ,in C The concentration of the EDTA standard solution is... V 303.26 is the amount of EDTA standard solution used, 10 is the molar mass of lead sulfate, and M is the mass of the sample.

2. The test method as described in claim 1, characterized in that, The cleaning process described in step 1 includes: washing the positive electrode plate with pure water until the pH reaches 6-7, and then drying and cooling it for later use.

3. The test method as described in claim 1, characterized in that, The sampling process in step 1 includes: randomly selecting multiple grid units on the grid of the formed positive electrode plate, separating, collecting, and grinding the active material within the grid unit range for later use.

4. The test method as described in claim 1, characterized in that, In step 2, the first mixture includes a first state and a second state. The first state is when the first mixture produces microbubbles, and the second state is when the second mixture does not contain microbubbles. When the first mixture enters the second state, it undergoes filtration.

5. The test method as described in claim 1, characterized in that, The sodium chloride in step 3 has a mass fraction of 25-26%, and the standing time is 8-16 hours.

6. The test method as described in claim 1, characterized in that, The first mixture was prepared using a vibration device.

7. The method for testing the lead sulfate content in the positive electrode plate of a lead-acid battery after formation, as described in claim 6, is characterized in that... The vibration device includes an oscillator and an ultrasonic cleaner.

8. The test method as described in claim 1, characterized in that, The first filtration process includes: placing quantitative filter paper on a funnel, wetting the quantitative filter paper with glacial acetic acid, filtering and separating the second mixture using the quantitative filter paper to obtain filtrate and filter residue, and washing the filter residue with acetic acid-ethanol washing solution to obtain pure filter residue.

9. The test method as described in claim 1, characterized in that, The second filtration step includes: separating the second mixture using quantitative filter paper to obtain a second filtrate and a second filter residue, and rinsing the second filter residue with sodium chloride washing solution until the second filter residue is free of lead ions.

10. The test method as described in claim 1, characterized in that, The steps of the lead ion EDTA titration method include: diluting the test sample and adjusting the pH to 5-6, then adding hexamethylenetetramine solution, ascorbic acid, and dimethylphenol orange indicator to prepare a titrant solution; titrating the solution to be titrated with EDTA standard solution; stopping the titration after the solution turns bright yellow; and recording the amount of EDTA standard solution used in the titration.

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