Method and device for controlling and processing magnetic foreign matters of electrode material

Abstract

The invention relates to the technical field of power batteries, in particular to a magnetic foreign matter control processing method and device for an electrode material, and the method comprises the following steps: S1, detecting the content x and size of magnetic foreign matter particles in a raw material, if particles with the size larger than a first threshold value exist, demagnetizing or re-preparing the raw material, and otherwise, executing S2; s2, dispersing the raw materials in a solvent to obtain first slurry, detecting the magnetic foreign matter content y and the size of the first slurry, if particles with the size larger than a second threshold value exist, stopping the machine for retesting and filtering according to the result, and otherwise, executing S3; and S3, calculating the content z = x-y of the newly added magnetic foreign matters during stirring, if z is greater than a first preset content threshold value, stopping the machine for retesting, positioning a source and eliminating the source, and otherwise, outputting the slurry for coating. The method can comprehensively evaluate and control the risk of the magnetic foreign matters, and reduces or avoids the failure of the battery cell due to the magnetic foreign matters.

Description

Technical Field

[0001] This invention relates to the field of power battery technology, specifically to a method and apparatus for controlling and processing magnetic foreign matter in electrode materials. Background Technology

[0002] Currently, electric vehicles have entered the stage of mass production. As the core power source of the entire vehicle, the safety and reliability of the power battery directly determine the overall vehicle performance. However, in practical applications, magnetic foreign objects inside the power battery can easily cause differential pressure faults in the battery assembly, and in severe cases, even lead to thermal runaway. Such failures induced by magnetic foreign objects account for a significant proportion of the total battery failure modes, and have become a key hidden danger affecting the service life and safety performance of power batteries.

[0003] Meanwhile, the control of magnetic foreign objects in the production of power batteries has long been a core technical challenge in the industry. Due to the complex sources of magnetic foreign objects (including raw material introduction, equipment wear, environmental intrusion, etc.) and the large size range (from micrometers to sub-millimeters), traditional single-stage demagnetization or detection methods are difficult to achieve effective control throughout the entire process.

[0004] To effectively reduce the probability of battery assembly failure caused by magnetic foreign objects, significantly reduce after-sales maintenance costs and customer complaints, and ensure the quality stability of power battery mass production, it is urgent to research and propose a precise control method for magnetic foreign objects covering the entire battery production process. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for controlling magnetic foreign matter in electrode materials, which can comprehensively assess and manage the risks of magnetic foreign matter in electrode materials, and reduce or eliminate cell failures caused by magnetic foreign matter problems.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention discloses a method for controlling and processing magnetic foreign matter in electrode materials, which includes the following steps:

[0008] S1, detect the content x and size of magnetic foreign particles in the raw material. If there are magnetic foreign particles in the raw material with a size greater than the first threshold, then demagnetize the raw material or prepare the raw material again; otherwise, proceed to S2.

[0009] S2, the raw materials are uniformly stirred and dispersed in the solvent to obtain the first slurry. The content and size of magnetic foreign particles in the first slurry are detected. If there are magnetic foreign particles with a size greater than the second threshold in the first slurry, the machine is stopped for retesting. The filtration process is implemented according to the retest results to eliminate magnetic foreign particles with a particle size greater than the second threshold. Otherwise, proceed to S3.

[0010] S3, calculate the content z of newly added magnetic foreign particles during the stirring process, i.e. z = x - y. If z > the first preset content threshold, stop the machine for retesting. Based on the retest results, locate the source of the newly added magnetic foreign particles and eliminate the excessive magnetic foreign particles according to the source. Otherwise, output the first slurry for the coating process.

[0011] Furthermore, before the first slurry is output for the coating process, the process also includes: demagnetizing the first slurry in multiple stages to obtain the second slurry;

[0012] The content and size of magnetic foreign particles in the second slurry are detected. If there are no magnetic foreign particles with a size greater than the third threshold in the second slurry, and the content of magnetic foreign particles with a size less than or equal to the third threshold is less than or equal to the second preset content threshold, then the second slurry is output for the coating process; otherwise, grinding and refining are performed.

[0013] Furthermore, during multi-stage demagnetization, the demagnetization efficiency of magnetic foreign objects with a size ≤ the fourth threshold is ≥ the first preset threshold.

[0014] For magnetic foreign objects whose size is less than or equal to the fourth threshold and whose demagnetization efficiency is greater than or equal to the second preset threshold,

[0015] The first preset threshold is less than the second preset threshold.

[0016] Furthermore, before the second slurry is output for the coating process, the method further includes: adjusting the viscosity of the second slurry to a preset value, and then performing vacuum degassing to obtain the third slurry;

[0017] The content and size of magnetic foreign particles in the third slurry are detected. If there are no magnetic foreign particles with a size greater than the fifth threshold in the third slurry, and the content of magnetic foreign particles with a size less than or equal to the fifth threshold is less than or equal to the third preset content threshold, then the third slurry is output for the coating process; otherwise, filtration and impurity removal are performed.

[0018] Furthermore, the third and fifth thresholds are both 100 μm, and the second and third preset content thresholds are 1 psc / kg.

[0019] Furthermore, it also includes coating a third slurry onto a carrier to obtain an electrode sheet, and detecting the content and size of magnetic foreign matter on the surface of the electrode sheet to determine whether the electrode sheet meets the preset requirements.

[0020] Furthermore, when the content of magnetic foreign particles with a size ≤ third threshold in the second slurry exceeds a preset multiple of the preset content, the number of demagnetization stages is increased.

[0021] Furthermore, both the first threshold and the second threshold are 200 μm.

[0022] In a second aspect, the present invention discloses a magnetic foreign matter control and processing device for electrode materials, comprising:

[0023] The first execution unit is used to detect the content x and size of magnetic foreign particles in the raw material. If there are magnetic foreign particles in the raw material with a size greater than the first threshold, the raw material is demagnetized or the raw material is prepared again; otherwise, the next step is executed.

[0024] The second execution unit is used to uniformly stir and disperse the raw materials in the solvent to obtain the first slurry, detect the content and size of magnetic foreign particles in the first slurry, and if there are magnetic foreign particles with a size greater than the second threshold in the first slurry, the machine is stopped for retesting. Based on the retest results, a filtration process is implemented to eliminate magnetic foreign particles with a particle size greater than the second threshold; otherwise, the next step is executed.

[0025] The third execution unit is used to calculate the content z of newly added magnetic foreign particles during the stirring process, i.e., z = x - y. When z > the first preset content threshold, the machine is stopped for retesting. Based on the retest results, the source of the newly added magnetic foreign particles is located, and the excessive magnetic foreign particles are eliminated according to the source. Otherwise, the first slurry is output for the coating process.

[0026] Furthermore, it also includes a magnetic foreign object detection unit;

[0027] The magnetic foreign object detection unit includes a base, a guide rail, a slider, a limiting member, and a magnetic rod. The guide rail and the limiting member are connected to the base, and the limiting member encloses a detection area for placing the object to be tested. The slider is slidably connected to the guide rail, and the magnetic rod is fixed on the slider. The slider drives the magnetic rod to reciprocate horizontally above the detection area.

[0028] The present invention has the following unexpected beneficial effects:

[0029] The method described in this invention can improve the safety performance of battery cells and reduce the probability of failure. By intercepting oversized and excessive magnetic foreign objects throughout the entire process, it can significantly reduce serious failure problems such as differential voltage faults and thermal runaway caused by magnetic foreign objects, thereby improving the safety redundancy of power batteries. Furthermore, it can reduce the total lifecycle cost. On the one hand, precise control at the source and throughout the process reduces the cost of scrapping substandard slurry and electrode sheets; on the other hand, the reduced probability of cell failure reduces after-sales maintenance costs and customer complaints, improving the product's market reputation. Attached Figure Description

[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention.

[0031] Figure 1 A schematic flowchart of the magnetic foreign matter control and processing method for electrode materials according to an embodiment of the present invention is shown.

[0032] Figure 2 A schematic diagram of the detection process for the second slurry according to an embodiment of the present invention is shown.

[0033] Figure 3 A schematic diagram of the detection process for the third slurry according to an embodiment of the present invention is shown.

[0034] Figure 4 A schematic diagram of the structure of the magnetic foreign object detection unit according to an embodiment of the present invention is shown. Detailed Implementation

[0035] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0036] In one embodiment, the present invention discloses a method for controlling and processing magnetic foreign matter in electrode materials, see [link to relevant documentation]. Figure 1 As shown, it includes the following steps:

[0037] S1, detect the content x and size of magnetic foreign particles in the raw material. If there are magnetic foreign particles in the raw material with a size greater than the first threshold, then demagnetize the raw material or prepare the raw material again; otherwise, proceed to S2.

[0038] S2, the raw materials are uniformly stirred and dispersed in the solvent to obtain the first slurry. The content and size of magnetic foreign particles in the first slurry are detected. If there are magnetic foreign particles with a size greater than the second threshold in the first slurry, the machine is stopped for retesting. The filtration process is implemented according to the retest results to eliminate magnetic foreign particles with a particle size greater than the second threshold. Otherwise, proceed to S3.

[0039] S3, calculate the content z of newly added magnetic foreign particles during the stirring process, i.e. z = x - y. If z > the first preset content threshold, stop the machine for retesting. Based on the retest results, locate the source of the newly added magnetic foreign particles and eliminate the excessive magnetic foreign particles according to the source. Otherwise, output the first slurry for the coating process.

[0040] The method described in this invention can improve the safety performance of battery cells and reduce the probability of failure. By intercepting oversized and excessive magnetic foreign objects throughout the entire process, it can significantly reduce serious failure problems such as differential voltage faults and thermal runaway caused by magnetic foreign objects, thereby improving the safety redundancy of power batteries. Furthermore, it reduces the total lifecycle cost. On the one hand, precise control at the source and throughout the process reduces the cost of scrapping substandard slurry and electrode sheets; on the other hand, the reduced probability of battery cell failure reduces after-sales maintenance costs and customer complaints, improving the product's market reputation.

[0041] In step S1 of this invention, both the size and content of magnetic foreign objects in the raw materials are specifically detected. For magnetic foreign object particles with a size exceeding a first threshold, rigid treatment such as demagnetization or re-preparation is implemented. This directly addresses the core risk in battery production where large-sized magnetic foreign objects can easily puncture the separator and cause short circuits. Compared to the traditional, crude raw material control that only detects content and ignores size, this invention uses size-based interception to prevent potentially hazardous raw materials from entering subsequent mixing and coating processes, reducing ineffective costs such as slurry scrapping and equipment wear caused by raw material issues. If large particles exceeding the threshold are present in the raw materials, traditional processes may only trace the problem back to the raw materials after cell failure. However, this invention, through pre-screening, intercepts the risk of magnetic foreign objects at the beginning of the production process, avoiding a chain of quality problems caused by foreign objects in subsequent stages (mixing, dispersion, coating), such as slurry agglomeration and electrode defects.

[0042] Step S2 involves a secondary inspection of the magnetic foreign matter content and size in the first slurry. Particles with a size greater than the second threshold are subject to a shutdown, re-inspection, and filtration. This addresses the hidden risk of particle agglomeration during stirring (e.g., small particles coalescing into particles exceeding the threshold) despite passing raw material inspection. For example, particles in the raw material with a size ≤ the first threshold may agglomerate into particles exceeding the second threshold during stirring and dispersion due to solvent environment or mechanical action. The secondary inspection in step S2 effectively captures such problems, preventing substandard slurry from flowing into the coating process.

[0043] Step S3 quantifies the content z of newly added magnetic foreign matter during the mixing process using a formula. For cases where z > a first preset threshold, the source must be located and eliminated. This overcomes the limitations of traditional processes that only detect the final slurry content and cannot distinguish between raw material-borne and process-added foreign matter. Traditional processes typically filter out foreign matter added during mixing as soon as it exceeds the standard, but they do not address the underlying cause, potentially leading to recurring problems in subsequent batches. This invention, through source tracing and eradication, upgrades the control logic from passively handling the current batch to proactively preventing subsequent batches, significantly improving long-term production process stability.

[0044] Furthermore, the method described in this invention facilitates process iteration and quality traceability. The detection data and processing records of each link can form a complete traceability chain. If cell failure occurs later, it can quickly locate whether the problem is in the raw material link, slurry link, or mixing link, providing data support for process parameter optimization.

[0045] As a preferred embodiment of the present invention, see Figure 2 As shown, before the first slurry is output for the coating process, the process further includes: performing multi-stage demagnetization on the first slurry to obtain a second slurry; detecting the content and size of magnetic foreign particles in the second slurry; if there are no magnetic foreign particles with a size greater than a third threshold in the second slurry, and the content of magnetic foreign particles with a size less than or equal to the third threshold is less than or equal to a second preset content threshold, then the second slurry is output for the coating process; otherwise, grinding and refining are performed.

[0046] In this preferred embodiment, the first slurry undergoes multi-stage demagnetization enhancement: overcoming the limitations of single-stage demagnetization and achieving precise removal of small-sized magnetic foreign matter. Traditional single-stage demagnetization has limited efficiency in removing magnetic particles whose size is close to the threshold but not exceeding the limit. However, the multi-stage demagnetization method described above uses multiple sets of high-magnetic-field magnetic rods connected in series to significantly improve the overall removal rate by utilizing the superimposed adsorption effect. This solves the problem of insufficient control over small-sized, low-content magnetic foreign matter particles, and avoids the accumulation of such particles during electrode rolling and baking after they enter the coating process with the slurry, which could lead to localized overheating or micro-short circuits during subsequent cell charging and discharging.

[0047] This preferred embodiment specifies that the second slurry must simultaneously meet the following requirements: no particles larger than a third threshold, and a particle content with a size ≤ the third threshold ≤ a second preset content threshold. This ensures precise matching of the coating process's high requirements for slurry purity. If the slurry contains magnetic foreign particles larger than the third threshold, it can easily scratch the coating nozzle or cause bulges on the electrode surface during coating. If the content of small particles exceeds the standard, magnetic impurity points can easily form after the electrode dries, affecting the adhesion of the cell separator. Dual-standard testing can eliminate such hidden risks from the source.

[0048] Furthermore, this preferred embodiment does not employ the traditional method of discarding the entire container. Instead, it uses grinding and refining technology. This involves using equipment such as sand mills and ball mills to break down large particles exceeding the third threshold into smaller particles ≤ the third threshold, while simultaneously dispersing agglomerated small particles and reducing their content to within the second preset threshold. This allows the slurry, which would otherwise be discarded, to be recycled, significantly reducing the raw material costs of power battery production. At the same time, grinding and refining not only solves the problem of excessive magnetic foreign matter but also simultaneously improves the particle uniformity and viscosity of the slurry. This makes the second slurry more suitable for the thin and uniform coating requirements of the coating process, reducing cell voltage difference faults caused by uneven electrode thickness and indirectly improving cell consistency.

[0049] In a preferred embodiment of the present invention, when performing multi-stage demagnetization, the demagnetization efficiency of magnetic foreign objects with a size ≤ the fourth threshold is ≥ the first preset threshold, the demagnetization efficiency of magnetic foreign objects with a size < the fourth threshold and a size ≤ the third threshold is ≥ the second preset threshold, and the first preset threshold is < the second preset threshold.

[0050] From the perspective of demagnetization technology principles, the adsorption efficiency of magnetic foreign objects is positively correlated with particle size: small particles (size ≤ fourth threshold) have a large specific surface area, weak magnetism per unit mass, and easily flow around the magnetic rod with the slurry, making it difficult to achieve extremely high efficiency with single-stage or multi-stage demagnetization; while medium-to-large particles (fourth threshold < size ≤ third threshold) have stronger magnetism and larger volume, making them easier to capture by the magnetic rod, and achieving high efficiency is technically easier. Therefore, setting a uniform high demagnetization efficiency for all particle sizes may lead to a bias in process resources towards small particles that are difficult to remove (such as increasing the number of magnetic rod stages or increasing the magnetic field strength), which in turn reduces the control precision for medium-to-large particles. A graded efficiency standard can guide process resources to focus on high-risk medium-to-large particles, ensuring that their demagnetization efficiency meets the standard, while only requiring basic control for small particles, avoiding a reversal of risk priorities.

[0051] As a preferred embodiment of the present invention, see Figure 3 As shown, before the second slurry is output for the coating process, the process further includes: adjusting the viscosity of the second slurry to a preset value, and then performing vacuum degassing to obtain a third slurry; detecting the content and size of magnetic foreign particles in the third slurry; if there are no magnetic foreign particles with a size greater than the fifth threshold in the third slurry, and the content of magnetic foreign particles with a size less than or equal to the fifth threshold is less than or equal to the third preset content threshold, then the third slurry is output for the coating process; otherwise, filtration and impurity removal are performed.

[0052] In this preferred embodiment, by adjusting the viscosity of the second slurry to a preset value, it can be ensured that the slurry meets the process requirements for flowability and coating uniformity in the coating process. This avoids problems such as nozzle clogging and uneven electrode thickness due to excessive viscosity, or excessively thin coating and undercoating due to excessively low viscosity. Vacuum degassing thoroughly removes hidden air bubbles from the slurry, preventing them from forming defects such as pinholes and bulges on the electrode after coating and drying. The combination of these two methods provides a slurry base with satisfactory physical properties for subsequent electrode forming, reducing electrode rework caused by poor slurry conditions from the source, and ensuring the stability and yield of the coating process.

[0053] There may be hidden risks during the vacuum degassing process, such as metal wear and contamination during pipeline transportation and secondary agglomeration of particles caused by slurry settling. By dual detection of the size and content of magnetic foreign matter particles in the third slurry, new foreign matter that may be introduced in the degassing process can be detected in time, preventing qualified slurry after previous demagnetization and grinding from entering the coating process with risks. If the detection does not meet the standards, the excessive foreign matter can be removed by filtration, further strengthening the quality control line of the slurry before leaving the factory and ensuring that the slurry entering the coating process is free of any hidden risks.

[0054] In a preferred embodiment of the present invention, the third threshold and the fifth threshold are both 100 μm, and the second preset content threshold and the third preset content threshold are 1 psc / kg.

[0055] Unifying the third threshold (the upper limit of the size of the second slurry after multi-stage demagnetization) and the fifth threshold (the upper limit of the size of the third slurry after vacuum degassing) to 100μm means that magnetic foreign objects larger than 100μm are always considered absolutely prohibited from the demagnetization stage to the degassing stage. This avoids the high-risk particle leakage caused by differences in size thresholds at different stages (e.g., allowing 120μm particles during demagnetization but rejecting 80μm particles during degassing). For example, particles of 100-120μm might be acceptable during demagnetization but unacceptable after degassing due to the tightened threshold, causing process conflicts. By forming a closed-loop control system with zero tolerance for particles larger than 100μm throughout the entire process, the path for these particles to enter the coating process is completely blocked, avoiding the risk of such particles piercing the separator and causing short circuits in the battery cell from the source.

[0056] The second preset content threshold (the upper limit of the content of the second slurry) and the third preset content threshold (the upper limit of the content of the third slurry) are unified at 1 pcs / kg to ensure that the content of magnetic foreign matter smaller than 100μm remains at an extremely low level after multi-stage demagnetization and vacuum degassing. This avoids the accumulation of content exceeding the standard between stages due to differences in content standards, and ensures that the content of magnetic foreign matter in the slurry is always within a safe range from the completion of demagnetization to before coating. This prevents small particles from exceeding the standard due to agglomeration and secondary pollution during the degassing stage.

[0057] In a preferred embodiment of the present invention, the method further includes coating a third slurry onto a carrier to obtain an electrode sheet, and detecting the content and size of magnetic foreign matter on the surface of the electrode sheet to determine whether the electrode sheet meets the preset requirements.

[0058] The coating process does not guarantee the quality of the electrode sheet simply because the slurry is qualified. Hidden problems may arise during coating, such as metal wear of the coating equipment causing foreign matter to adhere to the electrode surface, dust adsorption during electrode transfer, and the accumulation of tiny particles from the slurry on the electrode surface after coating and drying. The newly added electrode surface inspection avoids the failure caused by secondary contamination or particle aggregation in the coating process, despite the magnetic foreign matter control efforts of previous stages. This ultimately forms a complete risk closed loop encompassing raw material interception, slurry control, and electrode quality control, ensuring that the electrodes entering cell assembly are free of any potential magnetic foreign matter hazards.

[0059] In a preferred embodiment of the present invention, when the content of magnetic foreign particles with a size ≤ third threshold in the second slurry exceeds a preset multiple of the preset content, the number of demagnetization stages is increased.

[0060] While individual magnetic foreign objects with a size ≤ the third threshold pose less of a threat than medium to large-sized particles, when their content exceeds a preset multiple, small particles are prone to agglomerating into large particles, or accumulating within the battery cell, leading to localized magnetic field anomalies, micro-short circuits, and other hidden problems. By adding a demagnetizing stage when the limit is exceeded, the demagnetizing efficiency of small particles can be specifically improved, reducing their content to a safe range and avoiding long-term risks caused by an excessive amount of low-risk small particles.

[0061] During production, factors such as batch differences in raw materials, variations in equipment wear, and fluctuations in solvent purity can all lead to instability in the content of small particles in the second slurry. A fixed number of demagnetization stages is insufficient to accommodate this variable; too few stages result in inadequate demagnetization, while too many stages lead to excessive energy consumption. The dynamic mechanism of triggering additional stages based on the degree of exceedance allows for flexible adjustment of the process intensity according to the actual content of small particles: maintaining the original stage number when the content is within acceptable limits, and strengthening demagnetization by adding stages when the content exceeds the limit. This makes the process more adaptable to uncertainties in production and reduces quality fluctuations caused by the mismatch between fixed parameters and actual variables.

[0062] In a preferred embodiment of the present invention, both the first threshold and the second threshold are 200 μm.

[0063] Magnetic foreign matter of 200μm and above is considered a high-risk particle posing a significant threat to battery cell safety. These particles can easily puncture the separator during subsequent coating and cell assembly processes, directly causing short circuits between the positive and negative electrodes, or lead to thermal runaway due to mechanical stress during charging and discharging. Unifying the first threshold (raw material end) and the second threshold (first slurry end) to 200μm means that any magnetic foreign matter particles larger than 200μm in the raw material must be intercepted through demagnetization or material replacement to prevent these high-risk particles from entering the mixing process. Even if the raw material is qualified, if particles larger than 200μm are generated during mixing due to equipment wear, agglomeration, or other unexpected events, the first slurry detection will also intercept them using the same standard, initiating retesting and filtration.

[0064] For example, after each measurement of the content and size of magnetic foreign particles, refer to Table 1 and fill in the statistical table based on the test results.

[0065] Table 1 Statistical Table of Test Results

[0066] Size status α β γ δ ζ raw material <![CDATA[a1]]> <![CDATA[b1]]> <![CDATA[c1]]> <![CDATA[d1]]> <![CDATA[e1]]> First slurry <![CDATA[a2]]> <![CDATA[b2]]> <![CDATA[c2]]> <![CDATA[d2]]> <![CDATA[e2]]> Second slurry <![CDATA[a3]]> <![CDATA[b3]]> <![CDATA[c3]]> <![CDATA[d3]]> <![CDATA[e3]]> Third slurry <![CDATA[a4]]> <![CDATA[b4]]> <![CDATA[c4]]> <![CDATA[d4]]> <![CDATA[e4]]>

[0067] In Table 1, α represents size ≤ 50 μm, β represents 50 μm < size ≤ 100 μm, γ represents 100 μm < size ≤ 150 μm, δ represents 150 μm < size ≤ 200 μm, and ζ represents 200 μm < size.

[0068] For the test results of raw materials, e1 must be 0 to ensure that there are no magnetic foreign particles with a size >200μm in the raw materials; otherwise, the raw materials must be demagnetized or the raw materials must be prepared again.

[0069] For the first slurry obtained by stirring and dispersing, e1 is also required to be 0 to ensure that there are no magnetic foreign particles with a size >200μm in the first slurry. Otherwise, the machine is stopped for retesting. Based on the retest results, a filtration process is implemented to eliminate magnetic foreign particles with a particle size >2 threshold.

[0070] For the second slurry after multi-stage demagnetization, c3, d3, and e3 must all be 0 to ensure that there are no magnetic foreign particles with a size >100μm in the second slurry; otherwise, grinding and refining should be performed.

[0071] When performing multi-stage demagnetization, the demagnetization efficiency of magnetic foreign objects in the α state (size ≤ 50 μm) is...

[0072] The demagnetization efficiency of magnetic foreign objects in the β state (i.e., those with a size between 50 μm and 100 μm)

[0073] Furthermore, when the content of magnetic foreign particles with a size ≤ the third threshold (i.e., 100 μm) in the second slurry exceeds 1.5 times the preset content, the number of stages of multi-stage demagnetization is increased by 2 times to ensure that there are no magnetic foreign particles with a size > 100 μm in the third slurry.

[0074] For the third slurry before the coating process, c3, d3, and e3 must all be 0 to ensure that there are no magnetic foreign particles larger than 100μm in the third slurry; otherwise, filtration and impurity removal must be performed. Furthermore, a4 and b4 must both be less than or equal to 1 pcs / kg.

[0075] It should be noted that there are no magnetic foreign particles with a size greater than 100μm in the third slurry. The number of demagnetization stages is increased according to the relationship between the raw material's c1 and d1 and the demagnetization efficiency.

[0076] In one embodiment, the present invention provides a magnetic foreign matter control and processing device for electrode materials, comprising:

[0077] The first execution unit is used to detect the content x and size of magnetic foreign particles in the raw material. If there are magnetic foreign particles in the raw material with a size greater than the first threshold, the raw material is demagnetized or the raw material is prepared again; otherwise, the next step is executed.

[0078] The second execution unit is used to uniformly stir and disperse the raw materials in the solvent to obtain the first slurry, detect the content and size of magnetic foreign particles in the first slurry, and if there are magnetic foreign particles with a size greater than the second threshold in the first slurry, the machine is stopped for retesting. Based on the retest results, a filtration process is implemented to eliminate magnetic foreign particles with a particle size greater than the second threshold; otherwise, the next step is executed.

[0079] The third execution unit is used to calculate the content z of newly added magnetic foreign particles during the stirring process, i.e., z = x - y. When z > the first preset content threshold, the machine is stopped for retesting. Based on the retest results, the source of the newly added magnetic foreign particles is located, and the excessive magnetic foreign particles are eliminated according to the source. Otherwise, the first slurry is output for the coating process.

[0080] In a preferred embodiment of the present invention, a magnetic foreign object detection unit is also included; the magnetic foreign object detection unit includes a base 1, a guide rail 2, a slider 3, a limiting member 4, and a magnetic rod 5. The guide rail 2 and the limiting member 4 are connected to the base 1, and the limiting member 4 encloses a detection area for placing the test piece 6; the slider 3 is slidably connected to the guide rail 2, and the magnetic rod 5 is fixed on the slider 3, and the slider 3 drives the magnetic rod 5 to reciprocate horizontally above the detection area.

[0081] Taking electrode detection as an example, the magnetic foreign object detection unit is placed on the detection stage, the electrode is placed in the detection area, and the circular magnetic rod 5 is mounted on the slider 3. The magnetic field strength of the magnetic rod 5 is greater than 12000GS, and the height of the magnetic rod 5 from the detection stage is 5cm. During detection, the magnetic rod 5 moves from one end above the electrode on the base 1 to the other end, and then the foreign objects on the magnetic rod 5 are collected to detect the quantity and size.

[0082] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A method for controlling and processing magnetic foreign matter in electrode materials, characterized in that, Includes the following steps: S1, detect the content x and size of magnetic foreign particles in the raw material. If there are magnetic foreign particles in the raw material with a size greater than the first threshold, then demagnetize the raw material or prepare the raw material again; otherwise, proceed to S2. S2, the raw materials are uniformly stirred and dispersed in the solvent to obtain the first slurry. The content and size of magnetic foreign particles in the first slurry are detected. If there are magnetic foreign particles with a size greater than the second threshold in the first slurry, the machine is stopped for retesting. The filtration process is implemented according to the retest results to eliminate magnetic foreign particles with a particle size greater than the second threshold. Otherwise, proceed to S3. S3, calculate the content z of newly added magnetic foreign particles during the stirring process, i.e., z = x - y. If z > the first preset content threshold, stop the machine for retesting. Based on the retest results, locate the source of the newly added magnetic foreign particles and eliminate the excessive magnetic foreign particles according to the source. Otherwise, output the first slurry for the coating process.

2. The method for controlling and processing magnetic foreign matter in electrode materials according to claim 1, characterized in that, Before the first slurry is output for the coating process, the process also includes: performing multi-stage demagnetization on the first slurry to obtain the second slurry; The content and size of magnetic foreign particles in the second slurry are detected. If there are no magnetic foreign particles with a size greater than the third threshold in the second slurry, and the content of magnetic foreign particles with a size less than or equal to the third threshold is less than or equal to the second preset content threshold, then the second slurry is output for the coating process; otherwise, grinding and refining are performed.

3. The method for controlling and processing magnetic foreign matter in electrode materials according to claim 2, characterized in that: When performing multi-stage demagnetization, the demagnetization efficiency of magnetic foreign objects with a size ≤ the fourth threshold is ≥ the first preset threshold. For magnetic foreign objects whose size is less than or equal to the fourth threshold and whose demagnetization efficiency is greater than or equal to the second preset threshold, The first preset threshold is less than the second preset threshold.

4. The method for controlling and processing magnetic foreign matter in electrode materials according to claim 2, characterized in that, Before the second slurry is output for the coating process, the process also includes: adjusting the viscosity of the second slurry to a preset value, and then performing vacuum degassing to obtain the third slurry; The content and size of magnetic foreign particles in the third slurry are detected. If there are no magnetic foreign particles with a size greater than the fifth threshold in the third slurry, and the content of magnetic foreign particles with a size less than or equal to the fifth threshold is less than or equal to the third preset content threshold, then the third slurry is output for the coating process; otherwise, filtration and impurity removal are performed.

5. The method for controlling magnetic foreign matter in electrode materials according to claim 4, characterized in that: The third and fifth thresholds are both 100 μm, and the second and third preset content thresholds are 1 psc / kg.

6. The method for controlling magnetic foreign matter in electrode materials according to claim 4, characterized in that: It also includes coating a third slurry onto a carrier to obtain an electrode sheet, and detecting the content and size of magnetic foreign matter on the surface of the electrode sheet to determine whether the electrode sheet meets the preset requirements.

7. The method for controlling magnetic foreign matter in electrode materials according to claim 2, characterized in that: When the content of magnetic foreign particles with a size ≤ third threshold in the second slurry exceeds a preset multiple of the preset content, the number of demagnetization stages is increased.

8. The method for controlling and processing magnetic foreign matter in electrode materials according to claim 1, characterized in that, The first threshold and the second threshold are both 200 μm.

9. A magnetic foreign matter control and processing device for electrode materials, characterized in that, include: The first execution unit is used to detect the content x and size of magnetic foreign particles in the raw material. If there are magnetic foreign particles in the raw material with a size greater than the first threshold, the raw material is demagnetized or the raw material is prepared again; otherwise, the next step is executed. The second execution unit is used to uniformly stir and disperse the raw materials in the solvent to obtain the first slurry, detect the content and size of magnetic foreign particles in the first slurry, and if there are magnetic foreign particles with a size greater than the second threshold in the first slurry, the machine is stopped for retesting. Based on the retest results, a filtration process is implemented to eliminate magnetic foreign particles with a particle size greater than the second threshold; otherwise, the next step is executed. The third execution unit is used to calculate the content z of newly added magnetic foreign particles during the stirring process, i.e., z = x - y. When z > the first preset content threshold, the machine is stopped for retesting. Based on the retest results, the source of the newly added magnetic foreign particles is located, and the excessive magnetic foreign particles are eliminated according to the source. Otherwise, the first slurry is output for the coating process.

10. The magnetic foreign matter control and processing device for electrode materials according to claim 9, characterized in that, It also includes a magnetic foreign object detection unit; The magnetic foreign object detection unit includes a base, a guide rail, a slider, a limiting member, and a magnetic rod. The guide rail and the limiting member are connected to the base, and the limiting member encloses a detection area for placing the object to be tested. The slider is slidably connected to the guide rail, and the magnetic rod is fixed on the slider. The slider drives the magnetic rod to reciprocate horizontally above the detection area.

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