Method for monitoring metal impurities for coating a baking oven and tab production process

Abstract

The present application relates to the technical field of pole piece processing, in particular to a metal impurity monitoring method for a coating oven, a plurality of dust collecting devices are equidistantly arranged in the oven, and are well marked; after the oven runs for a certain time, the dust collecting devices are taken out, samples are extracted, the dust collecting devices are put into beakers containing alcohol for washing and stirring, each beaker is well marked, the beakers are heated until the alcohol completely volatilizes, the impurities collected by the dust collecting devices are obtained, and the impurities are weighed, numbered and analyzed by EDS energy spectrum to detect the element types; the cleanliness of each area of the oven is distinguished by the weight of the impurities, whether the impurities contain metal impurities and the area of the oven where the metal impurities are located are analyzed, the oven is cleaned and investigated according to the analysis result of the cleanliness, the method avoids that the metal impurities pierce the diaphragm and the pole piece mixes with dust or metal impurities, is more conducive to investigating the problem area, is convenient for subsequent problem tracing, and improves the production efficiency.

Description

Technical Field

[0001] This invention relates to the field of electrode processing technology, specifically to a method for monitoring metal impurities in a coating baking oven and an electrode production process. Background Technology

[0002] Currently, the drying methods for electrodes are as follows: (1) far-infrared radiation drying; (2) double-sided air supply floating drying; (3) conventional convection hot air drying; (4) circulating hot air impact drying;

[0003] (5) Superheated steam drying; (6) Microwave drying. The basic principle of drying is to use heating to vaporize water or other solvents and remove the generated steam, thereby removing moisture from solid materials.

[0004] In the battery electrode manufacturing process, an increasing number of online inspection technologies are being adopted to effectively identify manufacturing defects, reject defective products, and provide timely feedback to the production line. This allows for automated or manual adjustments to the production process, reducing the defect rate. Commonly used online inspection technologies include slurry characteristic testing, electrode quality inspection, and dimensional inspection. However, the detection of metallic impurities on the surface of coated electrodes has not received sufficient attention. Coated electrodes need to be dried in an oven, and currently, most production lines have relatively long ovens. Within this area, metallic impurities are highly likely to be introduced, and the source of introduction is difficult to detect. Summary of the Invention

[0005] To address the aforementioned problems, this invention discloses a method for monitoring metallic impurities in the baking section. By collecting impurities from different areas within the oven and conducting a series of tests on the collected impurities, the source of the impurities can be quickly identified through comparison of the results. This allows for timely inspection and cleaning of the oven, solving the problem of difficulty in monitoring metallic foreign objects during the baking stage and improving inspection and cleaning efficiency, thereby enhancing production efficiency.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for monitoring metallic impurities in a coating baking oven, comprising the following steps:

[0008] Step S1: Divide the oven passage into zones and collect dust from each zone;

[0009] Step S2: Extract samples of dust collected from each area separately to obtain residue, record the residue weight data of each area and number the residue.

[0010] Step S3: Analyze and detect the types and proportions of metallic impurities in the residue;

[0011] Step S4: Obtain the baking oven area corresponding to the residue based on the residue number;

[0012] Step S5: Based on the types and proportions of metal impurities obtained in Step S3 and the baking oven area corresponding to the residue obtained in Step S4, clean and inspect the baking oven area with a metal content of ≥10%.

[0013] Step S6: Repeat steps S1-S4, compare the two detection results, and determine the baking oven area where the metal impurity introduction source is located based on the comparison results.

[0014] Optionally, in one embodiment of the present invention, step S1 further includes the following step:

[0015] Step S101: Divide the baking oven into several equally spaced areas;

[0016] Step S102: At least one dust collection device is installed in each area of ​​step S101, and the dust collection devices are marked.

[0017] Step S103: After the baking oven has been running for a set time, the dust collection device is removed and the sample is extracted.

[0018] Optionally, in one embodiment of the present invention, step S103 is set for at least seven days to ensure that the dust collection device collects enough dust and to improve the reliability of the results.

[0019] Optionally, in one embodiment of the present invention, in step S2, the sample extraction adopts the weighing method to extract impurities. In addition to the weighing method, other methods can also be used to extract the sample.

[0020] Optionally, in one embodiment of the present invention, the specific steps of the weighing method are as follows:

[0021] Step S201: Put the dust container of the dust collection device into a beaker containing alcohol for cleaning and stirring. After a preset time, take out the dust container and mark each beaker accordingly.

[0022] Step S202: Heat the beaker until the alcohol has completely evaporated, and obtain the residue;

[0023] Step S203: Weigh and number the residue obtained in step S202.

[0024] Optionally, in one embodiment of the present invention, the preset time for step S201 is 30 minutes.

[0025] Ensure that the dust container has sufficient cleaning time to allow the dust to dissipate.

[0026] Optionally, in one embodiment of the present invention, the dust collection device is a small negative pressure vacuum cleaner. The detection does not require a large amount of impurities, so a small negative pressure vacuum cleaner can be used. On the one hand, the amount of impurities is relatively small, the method is faster, and the results are obtained faster. On the other hand, the dust collection cup of the small negative pressure vacuum cleaner is small in size, which is convenient to operate and can be directly placed into the beaker.

[0027] Optionally, in one embodiment of the present invention, step S3 involves analyzing the elemental composition of the residue using EDS energy dispersive spectroscopy, or XRF spectroscopy.

[0028] Optionally, in one embodiment of the present invention, in step S5, the limit standard for the proportion of metal impurities is 10%. If the proportion of metal impurities exceeds 10%, the corresponding baking oven area needs to be cleaned and inspected.

[0029] An electrode manufacturing process includes the aforementioned method for detecting metal impurities in a baking oven. The electrode manufacturing process remains the same, but the detection method of this solution is added to the baking process of the electrode. Through this detection method, the source of metal impurities can be quickly identified, thereby improving the quality of electrode production and thus improving the quality of the battery.

[0030] Beneficial effects of the invention

[0031] The present invention provides a method for monitoring metal impurities in a coating baking oven. The implementation of the method does not interfere with normal production. The method uses a weighing method for sample extraction, which is highly accurate. It also searches for metal impurities in the residue. The entire method uses multiple samples for reference to quickly determine the cleanliness level of different areas of the baking oven. Then, manual intervention is used to check and clean each area of ​​the baking oven to ensure the production quality of the electrode sheets and prevent dust and metal impurities from mixing into the electrode sheets. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0033] Figure 1 Flowchart of the steps and methods in Embodiment 1 of the present invention;

[0034] Figure 2 Flowchart of step S1 in Embodiment 1 of the present invention;

[0035] Figure 3 The detailed operation flowchart of the weighing method in step S2 of Embodiment 1 of the present invention. Detailed Implementation

[0036] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structure, features and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0037] Example 1

[0038] The baking time required for electrodes is relatively long, and impurities can easily get mixed into the electrodes, causing defects. Therefore, dust collection and monitoring during the baking process is necessary to facilitate troubleshooting and cleaning of the baking equipment and improve electrode quality. To address this, a method for monitoring metal impurities in coating baking ovens is proposed.

[0039] like Figure 1 As shown, the method specifically includes the following steps:

[0040] A method for monitoring metallic impurities in a coating baking oven, comprising the following steps:

[0041] Step S1: Divide the oven passage into zones and collect dust from each zone;

[0042] like Figure 2 As shown, the steps are explained as follows: Step S1 also includes the following steps:

[0043] Step S101: Divide the oven channel into several regions at equal intervals. In this embodiment, the oven channel is divided into six regions at equal intervals.

[0044] Step S102: At least one dust collection device is set up in each area in step S101, and the dust collection devices are marked. In this embodiment, the specific markings are as follows: one side of all areas is numbered with odd numbers, i.e., 1, 3, 5, 7, 9, 11, and the other side is numbered with even numbers, i.e., 2, 4, 6, 8, 10, 12. Two dust collection devices are set up in each area of ​​the baking oven, respectively set on the inner sidewalls of the two sides of each area, and the dust collection devices are numbered 1-12.

[0045] Device Description: The dust collection device is a small negative pressure vacuum cleaner. The detection does not require a large amount of impurities, so a small negative pressure vacuum cleaner is sufficient. On the one hand, the amount of impurities is relatively small, the method is carried out quickly, and the results are obtained quickly. On the other hand, the dust collection cup of the small negative pressure vacuum cleaner is small in size, which is convenient to operate and can be directly placed into the beaker for cleaning.

[0046] Step S103: After the oven has been running for the set time, all dust collection devices are removed, and samples are extracted from each dust collection device individually. In this step, the oven has been running for at least seven days. In other embodiments, the oven has been running for two weeks or one month. The duration can be adjusted as needed, but it is necessary to ensure that the dust collection devices collect enough dust to meet the detection requirements to ensure the detection is effective. A relatively large amount of dust collected can improve the reliability of the results.

[0047] Dividing the area into an appropriate number of zones and installing dust collection devices can provide sufficient samples, which helps improve the accuracy and reliability of the final results. The more zones a region is divided into, the faster the subsequent investigation and location can be.

[0048] Step S2: Extract samples of dust collected from each area separately to obtain residue, record the residue weight data of each area and number the residue.

[0049] The residue number can be the same as the dust collection device number.

[0050] Instructions: Sample extraction uses a gravimetric method to extract impurities. While other methods can also be used, gravimetric extraction, though relatively simple, yields the most accurate results. Therefore, it is the first method used to ensure precise measurement of residue from all twelve samples. Gravimetric extraction should be performed in a high-cleanliness environment, such as a cleanroom or dust-free chamber, to prevent other impurities from entering the beakers.

[0051] The specific steps of the weighing method are as follows:

[0052] Step S201: The dust container of the dust collection device is placed into a beaker containing alcohol for cleaning and stirring. After a preset cleaning time, the dust container is removed and each beaker is marked accordingly, i.e., the twelve beakers are numbered 1-12. The preset cleaning time is set to 30 minutes. In other embodiments, the dust container can be cleaned using an ultrasonic cleaning device to ensure that the dust collected in the dust container is removed from the dust container.

[0053] Step S202: Heat the beaker until the alcohol is completely evaporated to obtain residue. After the alcohol evaporates, the residue in the beaker is in powder form.

[0054] Step S203: Weigh and number the residue obtained in step S202.

[0055] The residue is numbered according to the dust collection device number, which is numbered 1-12.

[0056] Step S3: Analyze and detect the types and proportions of metallic impurities in the residue;

[0057] In step S3, the types of metallic impurities in the residue are detected by EDS energy dispersive spectroscopy, and the elemental analysis of the residue can also be performed by XRF spectroscopy.

[0058] EDS (Energy Dispersive Spectroscopy) analysis method uses an EDS spectrometer to detect residues. Specific operating instructions are as follows:

[0059] 1. Dry the residue (freeze-dry / baking). Drying can be done using a laboratory drying oven or baking oven.

[0060] 2. Use glue to fix the residue and the detection metal plate of the EDS spectrometer together, and plate a layer of metal or carbon on the surface of the residue to improve conductivity;

[0061] 3. After placing the residue into the EDS spectrometer, start evacuating the vacuum. Once the pressure reaches the preset value, start adjusting the lens focus. Adjust left and right, first coarsely and then finely. After the image is roughly clear, start adjusting the astigmatism. Adjust both the x-axis and y-axis astigmatism. Finally, adjust the focus a second time to find a suitable position and then collect the energy spectrum.

[0062] 4. For the residue of a sample, three points are generally selected for energy spectrum acquisition. Select the area, obtain the energy spectrum, switch to real-time mode / view mode, double-click the area to save, and send the data to the folder.

[0063] A smaller residue weight indicates a higher level of cleanliness in the baking oven area, while a larger residue weight indicates a lower level of cleanliness in the baking oven area.

[0064] Step S4: Obtain the baking oven area corresponding to the residue based on the residue number;

[0065] The main function is to monitor elements such as nickel, cobalt, zinc, iron, copper, manganese, and chromium in the residue. Based on the residue's number, the corresponding dust collection device is determined. Then, based on the dust collection device's number, the installation location of the device in the baking oven is determined, indicating that the residue with detected metal impurities originates from the area of ​​the baking oven corresponding to the residue's number.

[0066] EDS (Energy Dispersive Spectroscopy) has high efficiency in detecting X-rays. It can measure and count the energy of X-ray photons of all elements within the analysis point at the same time, and obtain qualitative analysis results within minutes. In contrast, a spectrometer can only measure the characteristic wavelength of each element one by one, which is time-consuming. The EDS spectrometer has a simple structure, good stability and reproducibility, does not require focusing, and has no special requirements for the surface of the sample, making it suitable for analysis of rough surfaces.

[0067] Step S5: Based on the types and proportions of metal impurities obtained in Step S3 and the baking oven area corresponding to the residue obtained in Step S4, clean and inspect the baking oven area where the metal content proportion exceeds the standard.

[0068] When cleaning and inspecting the baking oven, focus on areas where the metal impurity content is ≥10%. Cleaning methods include wiping with an alcohol-moistened non-woven cloth or using a high-powered vacuum cleaner.

[0069] Here is some actual monitoring data for reference. This data is from 15 days of operation of the baking oven, with dust collection devices numbered 1-12. The main metal impurities detected were iron, cobalt, nickel, chromium, copper, and zinc. The actual monitoring data is as follows:

[0070] Impurity No. 1 weighs 15g, and the mass percentage of metallic impurities is 14%. The ratio of iron, cobalt, nickel, chromium, copper and zinc is 12:5:1:2:2:1.

[0071] Impurity No. 2 weighs 18g, with a metal impurity mass percentage of 12.6%, and the ratio of iron, cobalt, nickel, chromium, copper, and zinc is 13:6:2:2:2:1.

[0072] Impurity No. 3 weighs 11g, and the mass percentage of metallic impurities is 11.2%. The ratio of iron, cobalt, nickel, chromium, copper and zinc is 11:4:2:3:2:1.

[0073] Impurity No. 4 weighs 10g, and the mass percentage of metallic impurities is 10.7%. The ratio of iron, cobalt, nickel, chromium, copper, and zinc is 8:10:5:5:3:2.

[0074] Impurity No. 5 weighs 5g, and the mass percentage of metallic impurities is 10.2%. The ratio of iron, cobalt, nickel, chromium, copper, and zinc is 11:14:4:7:5:5.

[0075] Impurity No. 6 weighs 7g, and the mass percentage of metallic impurities is 9.6%. The ratio of iron, cobalt, nickel, chromium, copper and zinc is 12:7:3:5:2:2.

[0076] Impurity No. 7 weighs 4g, and the mass percentage of metallic impurities is 9.3%. The ratio of iron, cobalt, nickel, chromium, copper and zinc is 16:7:2:5:3:1.

[0077] Impurity No. 8 weighs 6g, and the mass percentage of metallic impurities is 10.5%. The ratio of iron, cobalt, nickel, chromium, copper and zinc is 16:8:3:5:4:1.

[0078] Impurity No. 9 weighs 3g, and the mass percentage of metallic impurities is 11.3%. The ratio of iron, cobalt, nickel, chromium, copper and zinc is 14:10:5:2:4:3.

[0079] Impurity No. 10 weighs 7g, and the mass percentage of metallic impurities is 9.4%. The ratio of iron, cobalt, nickel, chromium, copper and zinc is 11:9:7:5:6:4.

[0080] Impurity No. 11 weighs 8g, and the mass percentage of metallic impurities is 8.5%. The ratio of iron, cobalt, nickel, chromium, copper and zinc is 10:4:2:3:2:2.

[0081] Impurity No. 12 weighs 6g, and the mass percentage of metallic impurities is 8.5%. The ratio of iron, cobalt, nickel, chromium, copper, and zinc is 9:5:1:3:1:2.

[0082] From the sample data of the above 12 impurities, it can be seen that the dust collection devices No. 1-4 are close to the oven inlet and easily adsorb dust from the outside air. Therefore, the weight of the impurities is relatively high, and the mass of the metal impurities is also relatively large. Most of the impurities are carbon. Among the several metal impurities mainly detected by EDS spectrometer, iron and cobalt have relatively large mass proportions.

[0083] By specifically analyzing the proportion of each metallic impurity, the efficiency of identifying the sources of metallic impurities was improved.

[0084] Step S6: Repeat steps S1-S4, compare the two detection results, and determine the area of ​​the baking oven where the impurity introduction source is located based on the comparison results.

[0085] If both tests show a large number of impurities or metallic impurities in the same area of ​​the baking oven, the source of the impurities should be investigated and cleaned from that area of ​​the baking oven.

[0086] The secondary monitoring also involved 15 days of equipment operation, and the actual monitoring data is as follows:

[0087] Impurity No. 1 weighs 13g, and the mass percentage of metallic impurities is 3.5%. The ratio of iron, cobalt, nickel, chromium, copper and zinc is 12:5:1:2:2:1.

[0088] Impurity No. 2 weighs 15g, and the mass percentage of metallic impurities is 4.1%. The ratio of iron, cobalt, nickel, chromium, copper and zinc is 13:6:2:2:2:1.

[0089] Impurity No. 3 weighs 14g, and the mass percentage of metallic impurities is 1.2%. The ratio of iron, cobalt, nickel, chromium, copper and zinc is 11:4:2:3:2:1.

[0090] Impurity No. 4 weighs 12g, and the mass percentage of metallic impurities is 2.7%. The ratio of iron, cobalt, nickel, chromium, copper and zinc is 8:10:5:5:3:2.

[0091] Impurity No. 5 weighs 10g, and the mass percentage of metallic impurities is 3.3%. The ratio of iron, cobalt, nickel, chromium, copper, and zinc is 11:14:4:7:5:5.

[0092] Impurity No. 6 weighs 9g, and the mass percentage of metallic impurities is 4.1%. The ratio of iron, cobalt, nickel, chromium, copper and zinc is 12:7:3:5:2:2.

[0093] Impurity No. 7 weighs 10g, and the mass percentage of metallic impurities is 3.7%. The ratio of iron, cobalt, nickel, chromium, copper and zinc is 16:7:2:5:3:1.

[0094] Impurity No. 8 weighs 8g, and the mass percentage of metallic impurities is 3.1%. The ratio of iron, cobalt, nickel, chromium, copper, and zinc is 16:8:3:5:4:1.

[0095] Impurity No. 9 weighs 9g, and the mass percentage of metallic impurities is 2.7%. The ratio of iron, cobalt, nickel, chromium, copper, and zinc is 14:10:5:2:4:3.

[0096] Impurity No. 10 weighs 6g, with a metal impurity mass percentage of 2.5%, and the ratio of iron, cobalt, nickel, chromium, copper, and zinc is 11:9:7:5:6:4.

[0097] Impurity No. 11 weighs 7g, and the mass percentage of metallic impurities is 1.9%. The ratio of iron, cobalt, nickel, chromium, copper and zinc is 10:4:2:3:2:2.

[0098] Impurity No. 12 weighs 7g, and the mass percentage of metallic impurities is 2.4%. The ratio of iron, cobalt, nickel, chromium, copper and zinc is 9:5:1:3:1:2.

[0099] According to the data from the second test, the area near the oven inlet has a relatively high content of metal impurities because the oven inlet is in contact with the outside air. In this test, the middle area of ​​the oven passage also had a relatively high content of metal impurities. There are several reasons for this, and a specific inspection is needed.

[0100] This monitoring method can determine the area where foreign objects are introduced into the baking oven by comparing the weight of impurities and the detection results of metal impurities. It can quickly detect whether a large amount of metal impurities will be generated in the baking oven area. The standard line is 10% metal impurity content, and the metal impurity content <10% is within the allowable range. The detection results can be archived for easy traceability of subsequent problems, improve production efficiency, avoid excessive metal impurities from mixing into the electrode sheet and affecting the production of the electrode sheet, and remove metal impurities in a timely manner to prevent metal impurities from directly piercing the diaphragm and ensure a clean environment inside the baking oven.

[0101] One embodiment discloses an electrode manufacturing process, including the aforementioned method for monitoring metal impurities in a coating baking oven. With the electrode manufacturing process remaining unchanged, the aforementioned monitoring method is added to the electrode baking process. Through this monitoring method, the source of metal impurities can be quickly identified, the electrode production quality can be improved, and the occurrence of battery short circuits can be effectively reduced.

[0102] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for monitoring metal contamination for coating a baking oven, characterized in that: The method steps are as follows: Step S1, divide the baking oven channel into regions and collect dust in each region; Step S2, separately perform sample extraction on the dust collected in each region, obtain residues, record the residue weight data of each region, and number the residues; Step S3, analyze and detect the types and content proportions of metal impurities contained in the residues; Step S4, according to the residue number, obtain the residue corresponding baking oven region; Step S5, according to the types and content proportions of metal impurities obtained in step S3 and the residue corresponding baking oven region obtained in step S4, clean up and investigate the baking oven region with excessive metal content proportion; Step S6, repeat steps S1-S4, compare the detection results of two times, and determine the baking oven region where the metal impurity introduction source is located according to the comparison result; The step S1 further includes the following steps: Step S101, equally divide the baking oven into several regions; Step S102, set at least one dust collection device in each region in the step S101, and identify the dust collection device; The step S3 is to analyze the element types of the residues by EDS energy spectrum; In the step S5, the limit standard of the metal impurity proportion is 10%.

2. The method for monitoring metal contamination for coating a baking oven according to claim 1, wherein: The step S1 further includes the following steps: Step S103, after the baking oven runs for a set time, take out the dust collection device and perform sample extraction.

3. The method for monitoring metal contamination for coating a baking oven according to claim 2, wherein: The set time in the step S103 is at least seven days.

4. The method for monitoring metal contamination for coating a baking oven according to claim 1, wherein: In the step S2, the sample extraction adopts the weighing method to extract samples of impurities.

5. The method for monitoring metal contamination for coating a baking oven according to claim 4, wherein: The specific steps of the weighing method are as follows: Step S201, put the dust container of the dust collection device into a beaker containing alcohol for cleaning and stirring, take out the dust container after a preset time, and mark each beaker; Step S202, heat the beaker until the alcohol is completely volatilized to obtain residues; Step S203, weigh and number the residues obtained in step S202.

6. The method for monitoring metal contamination for coating a baking oven according to claim 5, wherein: The preset time in the step S201 is 30 minutes.

7. The method for monitoring metal contamination for coating a baking oven according to claim 5, wherein: The dust collection device is a small negative pressure dust collector.

8. A pole piece production process characterized by: A metal impurity monitoring method for a coated baking oven according to any one of claims 1-7.

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