A nondestructive testing method and system for transaction pricing of spent lithium-ion battery negative electrode sheets

Abstract

The application provides a nondestructive testing method and system for transaction pricing of waste lithium ion battery negative pole piece, relates to the technical field of waste lithium ion battery recycling and resource utilization, and has the technical scheme as follows: by setting the ultrasonic output power to change in stages, the change is matched with the damping change in the process of graphite coating peeling, and after peeling, the image segmentation is used to determine the graphite residue and copper foil damage, and then the effective mass meeting the condition is used to calculate the copper foil content, so that the graphite is peeled off while the copper foil damage is avoided, accurate and reliable copper foil content determination is realized, and the advantages of nondestructive, accurate and rapid determination of the copper foil content in the waste negative pole piece are achieved.

Description

Technical Field

[0001] This invention relates to the field of waste lithium-ion battery recycling and resource utilization technology, and more specifically, to a non-destructive testing method and system for pricing the trading of waste lithium-ion battery negative electrode sheets. Background Technology

[0002] In the spot market trading of waste lithium-ion batteries, fair pricing of unfilled negative electrode sheets requires rapid and non-destructive determination of the high-value copper foil content. Waste negative electrode sheets typically consist of an ultra-thin copper foil substrate only a few micrometers to tens of micrometers thick, and a dense graphite coating uniformly applied to both sides. The graphite coating also contains a small amount of binder to firmly adhere the graphite particles to the copper foil surface. Since copper foil accounts for the vast majority of the total value of the electrode sheet, accurately determining its content is a core aspect of pricing.

[0003] Currently, there are three main methods for determining the copper foil content in waste electrode sheets at the trading site. The first is the strong acid dissolution method, which uses strong acid to completely dissolve the copper foil and calculates the copper foil content based on the mass difference before and after dissolution. This method is destructive, requires several hours of reaction, and generates highly corrosive acidic wastewater, failing to meet the requirements of speed and environmental protection in spot trading. The second is the manual scraping method, which uses a blade to manually scrape off the graphite layer. The results are highly dependent on the operator's skill level, are labor-intensive and inefficient, and easily result in scraping off copper foil fragments or failing to completely remove graphite, leading to subjective errors exceeding 5%. The third is the constant-power ultrasonic physical peeling method. After cutting, drying, and weighing the sample electrode sheet, the operator immerses it in deionized water and ultrasonically treats it at a constant high power (e.g., 180W) for approximately 60 seconds. The copper foil content is calculated by peeling off the graphite and weighing the copper foil again. This method is considered promising because it does not involve strong acids and is relatively fast.

[0004] However, the constant-power ultrasonic physical peeling method has revealed serious flaws in practice. In the initial stage of ultrasonic treatment, the sample electrodes are covered with a complete graphite coating on both sides. This coating acts as a damping buffer, absorbing and dispersing most of the ultrasonic cavitation impact and protecting the underlying ultrathin copper foil. As the process progresses, the aqueous medium penetrates under the assistance of the acoustic field, causing the binder to swell, and the graphite coating begins to peel off unevenly and locally. The copper foil in the areas where the coating peels off first is directly exposed, but the ultrasonic cleaner continues to output constant high power, causing the energy originally dispersed by the graphite to concentrate and bombard the exposed copper foil. The ultrathin copper foil itself has extremely low mechanical strength, and without the graphite clamping, it rapidly curls at the edges, tears in the middle, and even produces numerous micropores under the impact of cavitation bubble rupture and high-frequency vibration. Towards the later stage of peeling, copper foil debris is washed away with the water flow, while graphite remains in the areas where the coating has not peeled off. The final measured quality of the copper foil deviates significantly from the true value, and parallel sample tests show extreme fluctuations, making it impossible to provide credible data and easily leading to disputes in transaction settlements.

[0005] Therefore, existing technologies cannot simultaneously achieve non-destructive, accurate, and rapid determination of copper foil content in the pricing of waste lithium-ion battery anode sheets, and urgently need to be improved. Summary of the Invention

[0006] The purpose of this invention is to provide a non-destructive testing method and system for pricing waste lithium-ion battery negative electrode sheets, which has the advantages of being able to non-destructively, accurately, and quickly determine the copper foil content in waste negative electrode sheets.

[0007] The present invention provides a non-destructive testing method for pricing the trading of waste lithium-ion battery negative electrode sheets, the method comprising the following steps: S1. Provide a sample electrode obtained from the waste electrode to be tested, and obtain the initial mass of the sample electrode; S2. Immerse the sample electrode in a liquid medium and perform ultrasonic ablation treatment. The ultrasonic ablation treatment includes at least a first stage, a second stage, and a third stage performed in chronological order. The ultrasonic output power of the first stage is lower than that of the second stage, and the ultrasonic output power of the third stage is lower than that of the second stage, so that the ultrasonic output energy matches the damping change during the removal of the graphite coating on the sample electrode surface. S3. Remove the stripped copper foil from the liquid medium and obtain the secondary mass of the copper foil; S4. Obtain a surface image of the copper foil; S5. Perform region segmentation on the surface image to obtain the surface cleanliness, which characterizes the degree of graphite residue, and the physical damage rate, which characterizes the degree of copper foil damage; S6. When the surface cleanliness meets the preset cleanliness condition and the physical damage rate meets the preset damage rate condition, the secondary mass is taken as the effective secondary mass, and the copper foil content of the sample electrode is calculated based on the effective secondary mass and the initial mass.

[0008] The above method enables non-destructive stripping of waste negative electrode sheets, avoids copper foil damage, and allows for accurate determination of copper foil content, thus providing reliable data for transaction pricing.

[0009] Furthermore, before performing ultrasonic ablation, the present invention further includes: Obtain the material property parameters of the sample electrode; Based on the material property parameters, determine the ultrasonic parameters for the first stage, the second stage, and the third stage. The ultrasonic parameters include at least the ultrasonic output power and duration.

[0010] The above scheme matches the ultrasonic parameters with the electrode material properties, improving the adaptability of peel control.

[0011] Furthermore, the ultrasonic ablation process in the second stage of the present invention includes: At least one peeling state parameter is obtained, which reflects the peeling state of the sample electrode in the liquid medium. Adjust the ultrasound output for the second stage based on the stripping status parameters.

[0012] The above solution achieves adaptive ultrasonic output through real-time peeling status feedback, thereby improving peeling effect and safety.

[0013] Furthermore, in the second stage, the present invention acquires at least one peeling state parameter and adjusts the ultrasonic output of the second stage according to the peeling state parameter, including: The first stripping state parameter of the liquid medium and the second stripping state parameter of the ultrasonic transducer are obtained. The first stripping state parameter reflects the light transmittance of the liquid medium, and the second stripping state parameter reflects the load impedance of the ultrasonic transducer. The graphite shedding degree parameter is determined based on the first peeling state parameter; Based on the second stripping state parameters, determine the damping change parameter; When the parameters of graphite shedding degree and damping change degree meet the first preset condition, the current ultrasonic output of the second stage is maintained. When the parameters of graphite shedding degree and damping change degree meet the second preset condition, the ultrasonic output power in the second stage is reduced. The second stage terminates when the parameters for graphite shedding degree and damping change degree meet the third preset condition.

[0014] The above solution, through dual detection of light transmittance and load impedance, accurately determines the stripping stage and optimizes the accuracy of power adjustment.

[0015] Furthermore, the second stage of the ultrasonic ablation process of the present invention includes multiple ultrasonic output units, and the method further includes: Obtain the unit ultrasound output parameters of multiple ultrasound output units; Based on the unit's ultrasonic output parameters, calculate the cumulative ultrasonic energy value applied in the second stage; Obtain the preset safe cumulative energy limit; The second stage terminates when the cumulative ultrasound energy value reaches the safe cumulative energy limit; Furthermore, in the second stage, when the sample electrode is determined to have entered a transitional state where graphite and bare copper coexist based on the peeling state parameters, the ultrasonic output power of the subsequent ultrasonic output unit is reduced, and / or the duration of the subsequent ultrasonic output unit is shortened.

[0016] The above scheme effectively prevents over-peeling and ensures the integrity of the copper foil by controlling the cumulative energy limit and transition state.

[0017] Furthermore, the present invention also proposes a method for region segmentation of a surface image, including: Based on the image features of the surface image, the first grayscale threshold and the second grayscale threshold are adaptively determined; Based on the first grayscale threshold and the second grayscale threshold, the graphite residue area and the physical damage area are segmented in the surface image.

[0018] The above scheme improves the accuracy of identifying graphite residues and physical damage through adaptive threshold segmentation.

[0019] Furthermore, the method of the present invention also includes: When the surface cleanliness does not meet the preset cleanliness condition, or the physical damage rate does not meet the preset damage rate condition, the corresponding processing operation is performed. The processing operations include at least one of the following: Auxiliary ultrasonic treatment is performed at a lower ultrasonic output power than that of the second stage to remove residual graphite; Discard the current secondary mass and adjust the ultrasonic parameters in at least one stage of the subsequent ultrasonic ablation process of the sample electrode according to the physical damage rate.

[0020] The above scheme provides compensation for situations where conditions are not met, thereby enhancing the fault tolerance and reliability of the testing process.

[0021] Furthermore, the processing operations of the present invention include: When the physical damage rate meets the preset damage rate condition and the surface cleanliness does not meet the preset cleanliness condition, the ultrasonic cleaning device is controlled to operate with auxiliary ultrasonic processing power, and the auxiliary ultrasonic processing power is lower than the ultrasonic output power of the second stage. If the surface cleanliness obtained after operation still does not meet the preset cleanliness conditions, then perform at least one of the following: adjust the supplementary parameters applied to the auxiliary ultrasonic power or the duration of the auxiliary ultrasonic treatment, or send a liquid medium heating command to the liquid medium to increase the temperature of the liquid medium; It counts the number of attempts to run and execute, and generates a prompt message for manual intervention when the number of attempts reaches the preset maximum number of attempts and the surface cleanliness still does not meet the preset cleanliness condition; When the physical damage rate does not meet the preset damage rate condition, a copper foil damage alarm is generated, the current secondary quality is discarded, and the adjustment amount is determined according to the physical damage rate. The adjustment amount is then applied to the ultrasonic parameters of at least one stage in the ultrasonic peeling process of the subsequent sample electrode.

[0022] The above approach, through auxiliary ultrasound, parameter adjustment, and trial counting, further optimizes the treatment effect of non-cleanliness standards and provides an alarm verification mechanism.

[0023] Furthermore, the present invention also includes: The transaction price of the waste negative electrode sheet is calculated based on the copper foil content and the preset transaction parameters.

[0024] The above scheme enables the direct conversion of copper foil content into transaction price, facilitating pricing applications.

[0025] Furthermore, the present invention also provides a non-destructive testing and pricing system for the trading and pricing of waste lithium-ion battery negative electrode sheets, comprising: a data processing terminal, an ultrasonic cleaning device, a weighing device, and an image acquisition device; the data processing terminal is configured to perform the steps in the above-described non-destructive testing method.

[0026] By integrating the relevant devices and executing the above methods, automated non-destructive testing and pricing are achieved, thus improving efficiency.

[0027] This invention provides a non-destructive testing method and system for pricing waste lithium-ion battery negative electrode sheets. By setting the ultrasonic output power to vary in stages, it matches the damping changes during the graphite coating peeling process. After peeling, it uses image segmentation to determine graphite residue and copper foil damage, and then uses the effective mass that meets the conditions to calculate the copper foil content. This avoids copper foil damage while peeling off graphite, achieving accurate and reliable copper foil content determination. It has the advantages of being able to determine the copper foil content in waste negative electrode sheets non-destructively, accurately, and quickly. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the method flow of the present invention; Figure 2 This is a schematic diagram of the process of the method of the present invention; Figure 3 This is a photograph of a sample electrode in a specific embodiment of the present invention, showing a graphite coating adhered to the surface of a copper foil substrate. Figure 4 This is a photograph of the copper foil after the graphite coating has been removed and dried following the implementation of the non-destructive testing method in a specific embodiment of the present invention. Detailed Implementation

[0029] The following description, in conjunction with the technical solution of the present invention, provides a clearer and more complete explanation of the relevant content. It should be noted that the embodiments described herein are only a part of the implementation methods of the present invention, and not all of them. Other implementation methods obtained by those skilled in the art based on the embodiments of the present invention without creative effort should also fall within the protection scope of the present invention. Furthermore, in the description of the present invention, the terms "first," "second," etc., are mainly for distinction and should not be construed as indicating relative importance.

[0030] See Figure 1This invention proposes a non-destructive testing method for pricing the trading of waste lithium-ion battery negative electrode sheets, comprising the following steps: S1. Provide a sample electrode obtained from the waste electrode to be tested, and obtain the initial mass of the sample electrode; S2. Immerse the sample electrode in a liquid medium and perform ultrasonic ablation treatment. The ultrasonic ablation treatment includes at least a first stage, a second stage, and a third stage performed in chronological order. The ultrasonic output power of the first stage is lower than that of the second stage, and the ultrasonic output power of the third stage is lower than that of the second stage, so that the ultrasonic output energy matches the damping change during the removal of the graphite coating on the sample electrode surface. S3. Remove the stripped copper foil from the liquid medium and obtain the secondary mass of the copper foil; S4. Obtain a surface image of the copper foil; S5. Perform region segmentation on the surface image to obtain the surface cleanliness, which characterizes the degree of graphite residue, and the physical damage rate, which characterizes the degree of copper foil damage; S6. When the surface cleanliness meets the preset cleanliness condition and the physical damage rate meets the preset damage rate condition, the secondary mass is taken as the effective secondary mass, and the copper foil content of the sample electrode is calculated based on the effective secondary mass and the initial mass.

[0031] At the waste trading site of a battery manufacturing plant, the unfilled negative electrode sheets awaiting pricing consist of ultra-thin copper foil ranging from a few micrometers to tens of micrometers thick and a dense graphite coating on both sides. The graphite coating contains adhesives that act as binders. Both parties need to quickly and non-destructively determine the actual mass percentage of the copper foil as a basis for pricing. Existing constant-power ultrasonic stripping methods directly immerse the sample electrode sheet in water, continuously impacting it with a single high power, without responding to changes in the electrode sheet's surface condition. In the initial stage of stripping, the intact graphite coating acts as a physical damping barrier, absorbing and dispersing most of the ultrasonic cavitation energy, resulting in minimal mechanical stress on the underlying ultra-thin copper foil. As moisture penetrates and causes the adhesive to swell and weaken, the graphite coating begins to peel off unevenly and locally. The first exposed copper foil areas instantly lose their damping protection, while the ultrasonic cleaning device continues to output the original high power, causing a sharp increase in acoustic energy density in these localized areas. Under continuous, high-intensity impacts from cavitation bubble bursting and high-frequency vibrations, the fragile ultra-thin copper foil rapidly curls at the edges, tears in the center due to excessive vibration amplitude, and may even be punctured with numerous tiny cavitation pinholes. During subsequent rinsing and removal, the already broken copper foil particles are easily washed away by the water flow and mixed with the detached graphite powder, while some firmly adhered graphite remains on the copper foil surface. This dual distortion of copper foil mass loss and graphite residue causes the secondary mass obtained after drying to deviate significantly from the true value. The copper foil content calculated based on this fluctuates wildly, failing to provide credible data for spot settlement and easily leading to price disputes on-site.

[0032] This embodiment reconstructs the detection process based on the matching relationship between ultrasonic output energy and the surface damping state of the electrode. In S1, the operator uses a clean cutter to randomly cut several sample electrodes from different locations in the batch of waste electrodes to be tested. For example, three sample electrodes with a size of 10cm × 10cm are cut and placed in a forced-air drying oven at 105°C for about 60 minutes to remove ambient moisture. They are then transferred to a desiccator to cool to room temperature. The total mass of the dried sample is weighed using an electronic analytical balance with an accuracy of 0.1mg. This initial mass data is transmitted in real time to a data processing terminal for storage. The total mass of a single sample weighing is controlled between 10g and 30g to reduce relative weighing error.

[0033] The ultrasonic ablation process of S2 is divided into three continuous dynamic stages. The output power of each stage is automatically switched in time sequence. The power level corresponds to the peeling process of the graphite coating on the electrode surface and the change of damping state.

[0034] The first stage is the immersion start-up stage, where the output power is controlled within a low range. At this time, both sides of the sample electrode are still covered with a basically intact graphite coating. The coating, acting as a physical damping layer, absorbs most of the ultrasonic cavitation impact energy, keeping the shear stress on the underlying ultrathin copper foil at an extremely low level. This low-power operation in this stage has two direct effects: first, with the assistance of the acoustic field, the liquid medium overcomes surface tension and penetrates into the copper foil interface along the micropores inside the graphite layer, causing the binder to swell and soften initially; second, the barrier effect of intact graphite damping minimizes the risk of damage to the copper foil in the initial stage. If high power is applied rashly at this stage, the coating interface, which is still in a strongly bonded state and has high damping, will be subjected to excessive local shear stress, potentially causing microscopic damage to the copper foil at the electrode edge.

[0035] The second stage is the main stripping stage, where the output power is increased to a higher range than in the first stage. After sufficient wetting and swelling in the early stage, the adhesive strength has significantly decreased, and the interfacial bonding force between graphite and copper foil has been greatly weakened. At this point, increasing the ultrasonic output can generate a strong cavitation effect and high-frequency oscillation in a short time, driving the graphite coating, which has lost its strong adhesive support, to rapidly detach from the copper foil surface in large chunks, achieving concentrated removal of graphite over a large area. The running time of this stage is strictly controlled to minimize the time the copper foil continues to be subjected to high-power impact after being partially exposed in the later stages.

[0036] The third stage is the cleaning and consolidation stage, where the output power is actively reduced to a range higher than the first stage but lower than the second stage. At this point, most of the graphite coating on the electrode surface has fallen off, and the ultrathin copper foil is essentially directly exposed to the liquid medium, its macroscopic mechanical structure no longer protected by the graphite damping layer. If the high power of the second stage is maintained, the exposed copper foil will directly bear cavitation impacts exceeding its physical yield limit, which is precisely the stage where curling, tearing, and pinholes are concentrated in the constant power scheme. This stage, by reducing the power, confines the liquid cavitation impact force below the bending yield limit of the ultrathin copper foil, thereby physically blocking the aforementioned damage path. At the same time, the reduced residual energy is still sufficient to maintain the micro-jet effect of the water flow, washing away the small amount of loose graphite particles adhering to the copper foil surface, completing the final peeling work without causing additional damage to the copper foil.

[0037] The power settings for the three stages are related to the copper foil design thickness and adhesive type of the specific electrode. The output is automatically matched after retrieving the bending yield stress limit and characteristic swelling weakening time from the built-in materials mechanics database in the data processing terminal, ensuring that the ultrasonic output is compatible with the physical tolerance of the current batch of samples. The entire ultrasonic physical exfoliation process does not use acids, alkalis, or other chemical solvents. The liquid medium can be deionized water, purified water, or distilled water, producing no toxic or harmful wastewater. The detached graphite powder can be precipitated and recycled.

[0038] In step S3, after ultrasonic stripping, the operator uses smooth plastic tweezers to gently remove the copper foil from the liquid medium by holding its edge. It is then gently rinsed in clean deionized water to remove any loose graphite particles adhering to the surface only by electrostatic force or weak adhesion. The rinsed copper foil is then placed back into a forced-air drying oven at 105°C for 60 minutes, transferred to a desiccator to cool to room temperature, and its secondary mass is measured using the same analytical balance. Once the balance reading stabilizes, the data is automatically sent to the data processing terminal.

[0039] Therefore, relying solely on the internal consistency of the weighing data for judgment cannot objectively distinguish whether the current secondary quality is too high due to graphite residue or too low due to copper foil damage and loss. This embodiment adds an image verification step after weighing, using the objective physical state of the copper foil surface as the basis for determining the validity of the secondary quality.

[0040] In S4, the operator lays the dried and cooled copper foil flat on the white LED uniform backlight panel at the bottom of the sealed standard light source reflection box. The image acquisition device captures high-resolution images of the front and back of the copper foil from the top of the box and transmits them to the data processing terminal in real time. The terminal converts the color images to grayscale images, removes noise through median filtering, and stretches the brightness distribution through histogram equalization to enhance the contrast between the dark graphite residue and the bright copper foil substrate, providing high-quality image input for subsequent region segmentation.

[0041] In S5, the data processing terminal performs region feature segmentation on the preprocessed grayscale image. Under uniform backlight illumination, the copper foil itself exhibits a bright metallic luster. Residual graphite, due to light absorption and scattering, appears as dark patches. Physical voids on the copper foil caused by tearing, curling, or cavitation pinholes allow strong white light from the backlight to penetrate directly, appearing as extremely bright areas in the image. Based on this physical difference, grayscale thresholds are used to divide the image pixels into three regions: pixels with grayscale values ​​below the first threshold belong to graphite residue areas; pixels with grayscale values ​​above the second threshold belong to physically damaged or void areas; and pixels with grayscale values ​​between the two thresholds belong to clean copper foil areas. Based on the pixel statistics of the three regions, two quantitative indicators, surface cleanliness and physical damage rate, are calculated. The average value of both sides is taken as the final evaluation value of the copper foil sample. Higher surface cleanliness indicates more thorough graphite removal; lower physical damage rate indicates better structural integrity of the copper foil during the peeling process.

[0042] In step S6, the data processing terminal compares the calculated surface cleanliness and physical damage rate with preset cleanliness and damage rate conditions, respectively. These two preset conditions correspond to acceptable peeling quality standards and are the thresholds for determining whether secondary weighing data can be included in content calculation. Only when the surface cleanliness meets the preset cleanliness condition and the physical damage rate meets the preset damage rate condition is the peeling process considered to have achieved the expected quality control target. This means that the current copper foil does not have an excessively high m2 due to the additional weight gain from residual graphite, nor does it have an excessively low m2 due to copper foil breakage and loss; its secondary mass can truly reflect the actual mass of the copper foil in the sample electrode. At this time, the secondary mass is marked as a valid secondary mass, and the data processing terminal calculates the percentage content of copper foil in the sample electrode based on this and the initial mass. Multiple parallel samples from the same batch undergo the above steps respectively. After each sample passes the validity determination, the arithmetic mean of the copper foil content of each sample is calculated as the characteristic copper foil content of the batch of waste negative electrode sheets.

[0043] If either surface cleanliness or physical damage rate fails to meet the corresponding conditions, it indicates that the peeling process deviated from the acceptable range in terms of graphite removal or copper foil protection. Secondary quality data is considered unreliable and will not be included in content calculations. There are corresponding remedial cleaning or parameter correction mechanisms to handle such anomalies.

[0044] In some implementations, surface cleanliness and physical damage rate are determined based on the region segmentation results of the surface image. Specifically, the area in the copper foil image excluding the background area is considered the effective detection area, denoted as Ae; the area of ​​the segmented graphite residue area is denoted as Ag; and the area of ​​the segmented physical damage areas such as pinholes, cracks, notches, or tears is denoted as Ad. Surface cleanliness C is calculated according to C = 1 - Ag / Ae, and physical damage rate D is calculated according to D = Ad / Ae.

[0045] The preset cleanliness condition is that the surface cleanliness C is not less than the preset cleanliness threshold C0, and the preset damage rate condition is that the physical damage rate D is not greater than the preset damage rate threshold D0. C0 and D0 can be preset according to the detection accuracy requirements, sample specifications, or transaction acceptance standards. When C≥C0 and D≤D0, it is determined that the graphite residue and physical damage on the surface of the peeled copper foil are within the allowable range, and the secondary quality can characterize the actual quality of the copper foil in the sample electrode.

[0046] Through the closed-loop process of peeling-verification-judgment described above, this embodiment ensures at the physical level that the ultrasonic impact intensity never exceeds the copper foil's withstand capability under the corresponding graphite-covered state, and at the data level, provides independent and reliable data based on the objective surface condition for each weighing result. Compared to the constant power scheme, this method produces direct improvements in the following aspects: During the peeling process, the third stage actively reduces the energy below the copper foil's bending yield limit, allowing the copper foil to be completely removed from the liquid medium without structural damage such as edge curling, overall tearing, or dense pinholes, thus eliminating mass loss caused by debris loss. In the image verification stage, surface cleanliness and physical damage rate serve as two parallel quantitative gating conditions, automatically filtering out sample data that are distorted due to incomplete graphite removal or copper foil damage, ensuring that the final mass data used for content calculation comes from thoroughly peeled and structurally intact copper foil. The calculated percentage of copper foil accurately reflects the true copper foil content of the batch of electrodes. Multiple tests on parallel samples show good consistency, and the relative standard deviation is kept low. This provides both parties with objective and reproducible pricing data, fundamentally reducing settlement disputes caused by inaccurate testing data. The entire testing process is completed within minutes, without the use of chemical reagents or the generation of acidic wastewater. Operators do not require a chemical analysis background, making it suitable for the combined requirements of speed, non-destructive testing, and environmental protection in waste trading environments.

[0047] Furthermore, in some preferred methods, prior to ultrasonic ablation, the following steps are included: obtaining material property parameters of the sample electrode; and determining ultrasonic parameters for a first stage, a second stage, and a third stage based on the material property parameters, wherein the ultrasonic parameters include at least ultrasonic output power and duration.

[0048] At spot trading sites for recycled lithium-ion batteries, the waste negative electrode sheets to be traded often come from different battery manufacturers, with significant differences in specifications and material formulations. When faced with mountains of electrode waste of varying sizes, testing personnel face significant risks if they rely solely on personal experience or use uniform, fixed ultrasonic parameters to peel all the sheets—for example, setting a constant high power and fixed time for all. Specifically, for ultra-thin copper foil with a thickness of only 6μm, a fixed high power will instantly break through its physical yield limit, accompanied by a piercing metallic tearing sound, causing severe curling and damage to the copper foil. For electrodes with thicker coatings or those using insoluble binders, a fixed low power or short time cannot completely remove graphite, resulting in a mottled surface and significant residue. This one-size-fits-all parameter setting not only imposes an additional burden of repeated rework on operators but also leads to extremely inconsistent test results for parallel samples, easily triggering heated disputes regarding pricing fairness at the trading site.

[0049] To address this, this invention proposes acquiring the material property parameters of the sample electrode before the ultrasonic peeling process officially begins, and automatically determining the ultrasonic parameters for each stage based on these parameters. Specifically, the operator can input the designed copper foil thickness via the numeric keypad on the control software interface of the data processing terminal, and select the electrode adhesive type via a drop-down menu. These material property parameters are the core basis for determining the physical resistance and chemical swelling characteristics of the electrode.

[0050] It is worth noting that the reason this invention uses material properties as a prerequisite for determining ultrasonic parameters is that the physical and chemical properties of the electrode directly determine its dynamic response in an ultrasonic cavitation field. The designed thickness of the copper foil directly maps to its bending yield stress limit, that is, the maximum local impact force that the copper foil can withstand without permanent mechanical deformation. At the same time, the type of electrode adhesive determines the characteristic swelling and weakening time of the adhesive in an aqueous medium. If ultrasonic parameters are blindly set without considering these material properties, excessive power in the first stage can easily generate shear stress that damages the edges of the copper foil before the adhesive softens, while insufficient power will prevent moisture from overcoming surface tension and penetrating quickly. If the power in the second stage is not limited in conjunction with the thickness of the copper foil, it can easily lead to overload and tearing of the exposed copper foil after local graphite detachment. If the adhesion of residual graphite is not considered in the third stage power, it is impossible to achieve thorough cleaning while protecting the copper foil.

[0051] After obtaining the material property parameters, the data processing terminal automatically accesses the built-in material mechanics yield database, retrieves the flexural yield stress limit value corresponding to the current copper foil thickness, and matches it with the swelling time curve corresponding to the current adhesive type. Based on this underlying physical and chemical data, the data processing terminal automatically calculates and outputs the ultrasonic output power and duration for the first stage, the second stage, and the third stage using a preset mapping algorithm. Subsequently, these precisely matched digital control commands are sent to the control chip of the ultrasonic cleaning device via the communication interface.

[0052] Through this automated parameter determination mechanism based on material property parameters, the operation of the ultrasonic cleaning device has shifted from blind output relying on human experience to precise control highly coupled with the physical properties of the electrode itself. This transformation ensures that the low power in the first stage is just enough to promote moisture penetration and binder swelling without damaging the copper foil; the high power in the second stage can efficiently destroy weakened interfaces while strictly controlling them below the yield limit of the current copper foil thickness; and the low power in the third stage can thoroughly rinse away trace residues within a safe range. This not only fundamentally eliminates the problem of copper foil damage or graphite residue caused by parameter mismatch, but also significantly reduces the reliance on the professional skills of operators. This allows for highly consistent and credible test data to be obtained for different batches and specifications of waste electrodes, laying a solid data foundation for subsequent fair trading and pricing.

[0053] After completing the first stage of immersion initiation according to the aforementioned steps, the second stage, the high-power main stripping stage, plays a crucial role in the large-area removal of the graphite coating. However, in real-world trading scenarios, if this stage operates continuously with fixed parameters, the physical state of the sample electrode surface will significantly change as stripping progresses. Specifically, the removal of the graphite coating from the electrode surface exhibits high non-uniformity, with graphite in certain localized areas detaching first, directly exposing the underlying ultrathin copper foil. Since these exposed areas lose the damping protection of the original graphite coating, and the ultrasonic cleaning device continues to blindly output constant high energy, the stress on the exposed copper foil rapidly exceeds its bending yield limit, leading to physical damage such as edge mechanical curling, central vibration tearing, and cavitation pinholes. This severe mismatch between energy and the actual bearing capacity of the electrode not only causes copper foil debris to be lost during subsequent rinsing, resulting in lower secondary weighing quality, but also causes drastic fluctuations in the test results of parallel samples, directly damaging the credibility of spot trading pricing.

[0054] To eliminate this energy overload window during the second stage, the present invention further proposes a scheme for internal dynamic control of the second stage. Furthermore, in some preferred embodiments, the ultrasonic ablation process of the second stage includes: acquiring at least one ablation state parameter, which reflects the ablation state of the sample electrode in the liquid medium; and adjusting the ultrasonic output of the second stage based on the ablation state parameter.

[0055] It is important to note that the core purpose of introducing the peeling state parameter is to reconstruct the dynamic matching relationship between ultrasonic impact intensity and electrode surface damping capability at the physical level, thereby going beyond simple conditional triggering logic. The peeling state parameter refers to any physical quantity that can directly or indirectly reflect the degree of graphite coating peeling off the sample electrode surface, the proportion of bare copper exposed, the concentration of suspended graphite in the liquid medium, or changes in the electrode's acoustic field damping characteristics. For example, this parameter can be derived from the detection of the optical properties of the liquid medium, characterizing the amount of graphite peeling through changes in transmittance; it can also be derived from the monitoring of the electrical characteristics of the ultrasonic transducer, reflecting the overall damping attenuation of the electrode through changes in load impedance. By acquiring these parameters, the evolution of the electrode surface from a state dominated by graphite coverage, to a state where graphite and bare copper coexist, and finally to a state dominated by bare copper exposure can be perceived in real time.

[0056] After obtaining the peeling state parameters, the ultrasonic output in the second stage is adaptively adjusted based on the specific surface condition reflected by these parameters. This adjustment can be implemented in multiple ways, including but not limited to adjusting the output power of the ultrasonic generator, adjusting the output frequency, shortening the duration of the current peeling unit, inserting a low-power buffer period between two peeling units, or prematurely terminating the second stage. The reason for providing such a rich set of adjustment dimensions is that the electrode's sensitivity and energy requirements vary significantly under different peeling processes; therefore, multi-dimensional energy intervention is necessary to achieve precise protection of the ultrathin copper foil.

[0057] Specifically, when the peeling parameters indicate that the sample electrode surface is still largely covered by graphite and the overall damping capacity is strong, a high ultrasonic energy output will be maintained to fully utilize the buffering effect of the graphite layer, promoting rapid fracture of the bonding interface and large-area graphite detachment. When the peeling parameters indicate that obvious bare copper has appeared in local areas and the overall damping capacity has begun to decrease, the ultrasonic output power will be reduced accordingly or the high-energy action time will be shortened to avoid high-intensity cavitation impacts directly bombarding the fragile exposed copper foil. When the peeling parameters indicate that most of the graphite on the electrode surface has detached and a large area of ​​copper foil has been exposed, the second stage of high-energy peeling will be immediately terminated, and the process will directly switch to the low-power cleaning stage.

[0058] Through the aforementioned dynamic control based on real-time sensing of the peeling state, the second stage transitions from an open-loop, fixed energy output state to a closed-loop, adaptive energy output state. This state transition fundamentally breaks the causal chain that leads to the loss of damping due to graphite shedding, which in turn triggers energy overload and copper foil damage. The ultrathin copper foil can be promptly identified and given appropriate energy protection after exposure, significantly reducing the probability of edge curling, central tearing, and cavitation pinholes. This makes the copper foil mass obtained from the secondary weighing significantly closer to the true value, and greatly improves the reproducibility of content determination results for parallel samples. Compared to the basic scheme that relies solely on fixed three-stage power changes, this method refines the matching of ultrasonic energy and damping state from the stage level to the real-time level within each stage, eliminating the risk of energy overload on a finer time scale.

[0059] Furthermore, the dynamic control during this process and the subsequent region segmentation verification based on surface images form a good synergy. During the stripping process, copper foil damage is proactively prevented through state parameters; after stripping, residual or damaged components are detected through image verification and remedial measures or parameter corrections are taken. Together, these two aspects constitute a dual quality assurance mechanism from process prevention to result verification, giving the entire non-destructive testing and valuation method higher adaptability and success rate. The specific implementation details regarding the use of specific sensors to acquire state parameters and the anomaly handling based on image verification will be further explained in subsequent embodiments.

[0060] Furthermore, in some preferred embodiments, in the second stage, at least one peeling state parameter is acquired, and the ultrasonic output of the second stage is adjusted according to the peeling state parameter, including: acquiring a first peeling state parameter of the liquid medium and a second peeling state parameter of the ultrasonic transducer, wherein the first peeling state parameter reflects the transmittance of the liquid medium and the second peeling state parameter reflects the load impedance of the ultrasonic transducer; determining a graphite shedding degree parameter based on the first peeling state parameter; determining a damping change degree parameter based on the second peeling state parameter; maintaining the current ultrasonic output of the second stage when the graphite shedding degree parameter and the damping change degree parameter meet a first preset condition; reducing the ultrasonic output power of the second stage when either the graphite shedding degree parameter or the damping change degree parameter meets a second preset condition; and terminating the second stage when either the graphite shedding degree parameter or the damping change degree parameter meets a third preset condition.

[0061] In actual testing at the spot trading site of waste electrode sheets, as ultrasonic peeling proceeds, the liquid in the cleaning tank gradually turns black, and the graphite coating on the electrode surface peels off unevenly and locally, like paint on a wall. The areas where the coating peels off first expose the ultra-thin copper foil, only a few micrometers thick, directly to the liquid, losing the protection of the thick buffer layer of graphite. If the equipment continues to output high power at the preset setting, cavitation bubbles in the liquid violently burst on the exposed copper foil surface. The resulting high-frequency microjet is like countless miniature hammers striking the extremely thin metal paper, causing the copper foil edges to curl rapidly, and even the center to be punctured, creating pinholes. These damaged copper shavings are easily washed away with the water flow during subsequent rinsing, resulting in a lower final weight of the copper foil. This detection error often leads to serious settlement disputes between the trading parties on-site. To accurately monitor this most vulnerable boundary, an 860nm infrared transmission probe is installed on the inner wall of the cleaning tank as an optical turbidity sensor to measure the transmittance of the liquid in real time, using this as the first peeling state parameter. Simultaneously, an impedance analysis module is integrated into the drive circuit of the ultrasonic transducer. This module extracts the real-time load impedance of the transducer by detecting the phase difference between voltage and current, serving as the second stripping state parameter. The reason for combining these two physical quantities for monitoring is that graphite stripping, when suspended in water, directly leads to increased liquid turbidity and decreased light transmittance. Furthermore, the thinning of the graphite coating reduces the acoustic load experienced by the transducer, causing a significant change in the equivalent impedance. These two parameters, one reflecting the amount of stripping from the liquid side and the other reflecting the damping change from the equipment side, form a reliable dual cross-validation.

[0062] After obtaining the transmittance data, the transmittance of the initial pure deionized water and the calibrated saturated transmittance when the graphite is completely suspended are combined to calculate the graphite shedding parameter. A higher value for this parameter indicates more graphite particles suspended in the water, resulting in a larger area of ​​graphite shedding from the electrode surface. Similarly, after obtaining the load impedance data, the initial impedance when the electrode is just placed in the tank and the graphite coating is intact, and the calibrated impedance when the copper foil is completely exposed, are combined to calculate the damping change parameter. This parameter directly reflects the true degree of reduction in mechanical damping on the electrode surface. It is worth noting that these two parameters are calculated and used simultaneously because a single physical parameter is easily affected by interference in actual operating conditions. For example, water temperature fluctuations or tiny air bubbles adhering to the probe can affect the transmittance reading, while electrode displacement within the tank or water flow disturbance can affect impedance detection. Combining both allows for accurate identification of the true physical coverage state of the electrode surface, effectively avoiding power adjustment errors caused by misjudgments from a single sensor.

[0063] Based on these two calculated core parameters, the second-stage peeling process is dynamically divided into three states and corresponding control actions are executed. When the graphite detachment degree parameter is less than 0.45 and the damping change degree parameter is less than 0.40, the first preset condition is met, and it is determined that the current state is dominated by graphite coverage. At this time, the graphite layer provides sufficient damping protection for the underlying copper foil, thus maintaining the current high power output and causing the softened graphite to detach rapidly over a large area. When the graphite detachment degree parameter reaches between 0.45 and 0.80, or the damping change degree parameter reaches between 0.40 and 0.75, the second preset condition is met, and it is determined that the sample has entered a transitional state where graphite and bare copper coexist. This means that the graphite damping in local locations has disappeared, and the exposed copper foil begins to face the risk of damage. In response, the power of the next ultrasonic output unit will be immediately reduced, for example, the output power will be reduced from 180W to 117W, while the duration of this unit will be shortened and the buffer time will be extended. This active energy reduction operation rapidly reduces the liquid cavitation impact force below the bending yield limit of the ultrathin copper foil, preventing the newly exposed, fragile copper foil from being shattered by high-frequency vibration. When the graphite shedding parameter is greater than or equal to 0.80, or the damping change parameter is greater than or equal to 0.75, the third preset condition is met, and the state of bare copper exposure is determined to be dominant. At this point, most of the graphite has already detached, and continuing to apply high power will only purely damage the copper foil structure. Therefore, the second stage is forcibly terminated, skipping all unexecuted short-term stripping units, and directly transitioning to the low-power third stage for gentle cleaning.

[0064] By using real-time state sensing and instantaneous power adjustment based on transmittance and load impedance, the key coupling parameters of ultrasonic output power and graphite damping on the copper foil surface are transformed from traditional open-loop presets to closed-loop dynamic matching. Throughout the peeling process, the mechanical stress on the copper foil is consistently kept within a safe range, and the physical damage rate is stably controlled at an extremely low level. This not only prevents the loss of copper foil fragments, ensuring the integrity and authenticity of the copper foil obtained from the secondary weighing, but also provides impeccable data support for subsequent accurate calculation of the copper foil percentage content and fair trading pricing, greatly enhancing the precision and credibility of on-site testing in spot trading.

[0065] The present invention further proposes a second-stage ultrasonic ablation process comprising multiple ultrasonic output units. The method further includes: acquiring unit ultrasonic output parameters of the multiple ultrasonic output units; calculating the cumulative ultrasonic energy value applied in the second stage based on the unit ultrasonic output parameters; acquiring a preset safe cumulative energy limit; terminating the second stage when the cumulative ultrasonic energy value reaches the safe cumulative energy limit; and, in the second stage, when it is determined from the ablation state parameters that the sample electrode has entered a transitional state where graphite and bare copper coexist, reducing the ultrasonic output power of the subsequent ultrasonic output units and / or shortening the duration of the subsequent ultrasonic output units.

[0066] In the non-destructive testing scenario of spot trading of waste lithium-ion battery negative electrode sheets, the main stripping stage employs multiple short-duration ultrasonic output units operating alternately. It is worth noting that although the single impact energy of each short-duration unit is controlled within the instantaneous yield limit of the ultra-thin copper foil, without macroscopic constraints on the overall energy input, the cumulative energy from repeatedly executing multiple units can easily lead to fatigue-induced cumulative damage to the copper foil. Specifically, this fatigue damage typically lies dormant during a single impact as microcracks gradually propagate, eventually erupting as delayed failure during subsequent rinsing or drying. To address this, this invention introduces a mechanism for calculating and monitoring the cumulative ultrasonic energy value. During the operation of each short-duration ultrasonic output unit, the actual output power and actual operating time of that unit are acquired in real time. Multiplying these two values ​​yields the applied energy value for that unit, which is then added to the energy values ​​of previously executed units to obtain the cumulative ultrasonic energy value from the start of the second stage to the current moment.

[0067] To define the safe boundary of this accumulated energy, a preset safe accumulated energy upper limit needs to be obtained. This upper limit is pre-set based on the material physical properties and thickness of the copper foil, representing the maximum accumulated energy that the ultrathin copper foil can withstand without fatigue damage under multiple pulsed ultrasonic impacts. For example, for a copper foil with a thickness of 8μm, the safe accumulated energy upper limit can be preset to 9000J. During the operation of each ultrasonic output unit in the main stripping stage, the accumulated ultrasonic energy value is continuously monitored. When this value reaches or exceeds the preset safe accumulated energy upper limit, regardless of the current graphite detachment state on the electrode surface, the second stage will be forcibly terminated, subsequent short-term stripping units will not be executed, and the process will directly switch to the third stage of low-power cleaning. This absolute energy limit, independent of surface condition determination, fundamentally eliminates the risk of copper foil fatigue damage caused by unlimited increases in the number of stripping cycles in pursuit of thorough stripping.

[0068] On the other hand, when the sample electrode is determined to have entered a transitional state where graphite and bare copper coexist, based on the peeling state parameters, it means that the graphite coating in some areas has already peeled off, and the ultrathin copper foil is now directly exposed to the liquid medium. If the subsequent ultrasonic output unit continues to operate at its original high power for an extended period, these newly exposed copper foil areas will be subjected to instantaneous high-energy impacts exceeding their tolerance, making them highly susceptible to edge curling or localized tearing. Therefore, upon determining that the transitional state has been entered, the parameters of the subsequent ultrasonic output unit are immediately adjusted downwards. Specifically, the ultrasonic output power of the subsequent unit can be reduced to 0.65 times the main peeling reference power, for example, from 180W to approximately 117W, while the duration of the subsequent unit is shortened to 5 seconds. This dual reduction in power and time allows the newly exposed copper foil to withstand lower instantaneous energy impacts and shorter single exposure times during subsequent peeling. The adjusted parameters are immediately applied to the next short-duration peeling unit, and during subsequent operation, the system dynamically determines whether to maintain the current parameters, further reduce them, or trigger termination conditions based on the latest peeling state. By using this strategy of converting the state determination result into energy output limit in real time, the energy output boundary is actively contracted at the critical moment when the graphite damping protection just begins to weaken. This directly prevents the unstable chain of constant high power bombardment after the appearance of local bare copper, which would lead to copper foil damage. At the physical level, the ultrasonic cavitation impact force is reconstrained below the bending yield limit of the ultrathin copper foil.

[0069] Furthermore, in some preferred methods, region segmentation of the surface image includes: adaptively determining a first grayscale threshold and a second grayscale threshold based on the image features of the surface image; and segmenting the graphite residue region and the physical damage region in the surface image based on the first grayscale threshold and the second grayscale threshold.

[0070] In the spot trading environment of waste lithium-ion battery recycling, the image acquisition environment is often complex and variable. Different industrial camera models may be used at different inspection points, the brightness of the light source panel may decrease over time, and stray light interference is unavoidable in the environment. These factors can cause the grayscale value range of the same physical area in the acquired copper foil surface grayscale images to drift across different inspection batches. If a pre-set fixed grayscale threshold is used for region segmentation, misjudgment is highly likely. For example, a graphite residue area in one batch of images may be misjudged as pure copper foil due to its overall brightness, resulting in an inflated cleanliness rating; or tiny reflective points on pure copper foil in another batch of images may be incorrectly identified as penetrating pinhole damage, leading to an inflated damage rate. This inaccurate segmentation caused by fluctuations in the image acquisition environment directly leads to severely inaccurate calculations of surface cleanliness and physical damage rate, resulting in the incorrect discarding of valid weighing data or the incorrect acceptance of invalid data, which can easily cause settlement disputes at the trading site.

[0071] To address this, this invention proposes adaptively determining a first grayscale threshold and a second grayscale threshold based on the image features of the surface image. Specifically, the first grayscale threshold is primarily used to distinguish between low-brightness graphite residue areas and medium-brightness pure copper foil areas. When determining the first grayscale threshold, the grayscale histogram distribution characteristics of the current surface image are analyzed, the grayscale positions corresponding to the peak values ​​in the dark areas are extracted, and an optimal boundary value is adaptively calculated using statistical measures such as inter-class variance. This adaptive calculation method based on the statistical characteristics of the image's own dark areas allows the first grayscale threshold to automatically adjust to the global or local grayscale distribution of the current image, thereby accurately stripping away graphite residue pixels. Besides being based on global grayscale histogram statistics, the adaptive determination of the first grayscale threshold can also be achieved based on the contrast characteristics of local areas of the copper foil or an adaptive version of the watershed algorithm.

[0072] The second grayscale threshold is primarily used to distinguish between areas of pure copper foil with intermediate brightness and areas of extremely high brightness caused by physical damage or light transmission through gaps. When the copper foil is cracked, torn, or has pinholes due to cavitation, the strong light from the backlight will directly penetrate these physical gaps, appearing as extremely high brightness in the image. To determine the second grayscale threshold, the actual average brightness of the white LED backlight under unobstructed conditions is collected, and the threshold is dynamically adjusted based on this actual average brightness. For example, the measured average grayscale value of the backlight can be appropriately increased to serve as the bright area threshold for identifying penetrating gaps. This dynamic adjustment mechanism based on the actual brightness of the backlight effectively eliminates ambient light interference and brightness reference shifts caused by light source aging, ensuring accurate identification of physically damaged areas. Alternatively, the second grayscale threshold can be combined with a manually set default brightness threshold and linearly offset calibrated based on the collected ambient brightness.

[0073] After adaptively determining the first and second grayscale thresholds, these two dynamic thresholds are used to traverse every pixel of the surface image for three-zone classification. Pixels with grayscale values ​​below the first grayscale threshold are marked as graphite residue pixels, pixels with grayscale values ​​above the second grayscale threshold are marked as physical damage or void pixels, and pixels between the two thresholds are marked as pure copper foil pixels. Through this processing, the image is transformed from an original undivided grayscale pixel matrix state into a aggregated description state where each pixel is clearly classified. The true distribution of graphite residues is accurately mapped, no longer masked by an overall bright image, nor exaggerated by an overall dark image. At the same time, physical damage such as tiny pinholes and edge tears on the copper foil are correctly identified as abnormal bright area pixels, avoiding confusion with bright spots caused by ambient light interference.

[0074] This adaptive dual-threshold segmentation mechanism transforms segmentation accuracy from relying on fixed prior experience to real-time adaptation to current image features and light source conditions. Even under conditions of camera replacement, reduced light source brightness, or interference from different ambient lighting environments, the first and second gray-scale thresholds automatically adjust, ensuring highly stable identification of graphite residue and physical damage areas. The calculated surface cleanliness and physical damage rate maintain good consistency and repeatability across different on-site terminals, enabling mutual recognition of detection results under different locations, personnel, and machines, providing solid technical credibility for settlement documents between spot trading parties. Compared to simply fixing thresholds, this mechanism does not require all on-site terminals to maintain strictly consistent imaging conditions, significantly reducing system deployment and maintenance costs, making image verification a truly reliable quality inspection method that can be practically implemented on-site. The two quantitative indicators of surface cleanliness and physical damage rate obtained from the segmentation results will provide accurate and reliable basis for subsequent data validity determination and automatic parameter correction.

[0075] Furthermore, in some preferred embodiments, when the surface cleanliness does not meet the preset cleanliness condition, or the physical damage rate does not meet the preset damage rate condition, a processing operation corresponding to the non-compliance condition is performed; the processing operation includes at least one of the following: performing auxiliary ultrasonic processing at an ultrasonic output power lower than that of the second stage to remove residual graphite; discarding the current secondary mass, and adjusting the ultrasonic parameters in at least one stage of the subsequent ultrasonic ablation process of the sample electrode according to the physical damage rate.

[0076] In the continuous testing process of spot trading of waste lithium-ion battery negative electrode sheets, due to microscopic differences in the binder distribution between different batches of electrode sheets, or slight deviations between the initial ultrasonic parameter settings and the current electrode sheet condition, abnormal situations often arise where the surface cleanliness or physical damage rate cannot simultaneously meet the preset thresholds after the aforementioned image segmentation calculations. Directly determining the test as a failure and discarding the data not only wastes samples but also severely slows down the on-site trading process; forcibly using manual scraping for remediation introduces significant subjective errors. To address this, this invention constructs a processing mechanism based on automatic anomaly type triage, enabling the testing process to possess self-healing and adaptive capabilities.

[0077] Specifically, when the surface cleanliness does not meet the preset cleanliness condition, but the physical damage rate meets the preset damage rate condition, it indicates that the macroscopic mechanical structure of the copper foil remains intact, but trace amounts of unremoved graphite particles still adhere to the surface. In this case, auxiliary ultrasonic treatment is directly performed. It is worth noting that the output power of the auxiliary ultrasonic treatment is strictly limited to a level lower than the main peeling power of the second stage. This is because at this point, more than 90% of the graphite damping layer on the electrode surface has disappeared, leaving the ultrathin copper foil completely exposed. If the high power of the second stage is continued, it is highly likely that the originally intact copper foil will curl or tear at the edges. By applying low-power auxiliary ultrasound, the residual graphite particles with strong adhesion or located in the acoustic shadow zone can be completely peeled off using the gentle scouring effect of the liquid microjets without exceeding the bending yield limit of the copper foil. After the auxiliary treatment is completed, the rinsing, drying, weighing, and image verification steps are repeated, thus salvaging the current test data without replacing the sample and significantly improving the success rate of a single sampling.

[0078] On the other hand, when the physical damage rate fails to meet the preset damage rate condition, it indicates that local acoustic energy density overload occurred during the peeling process, leading to visible or microscopic physical damage to the copper foil. In this case, some copper foil fragments have already been lost with the water flow, and the currently obtained secondary quality is significantly lower than the true value. Continuing to use this data for pricing will directly result in economic losses for the buyer. Therefore, the current secondary quality must be decisively discarded, and a copper foil damage alarm message must be generated on the control interface. More importantly, to prevent the next batch of parallel samples from repeating the same mistake, the ultrasonic parameters in at least one stage of the ultrasonic peeling process of the subsequent sample electrodes should be automatically adjusted based on the current physical damage rate value. For example, the main peeling reference power in the second stage can be proportionally reduced, or the duration of a single ultrasonic output unit can be shortened, depending on the degree of damage exceeding the standard. This approach of correcting the feedforward control parameters based on the posterior damage result enables the detection parameters of subsequent batches to quickly converge to a safe range, effectively preventing a vicious cycle of continuous damage.

[0079] In practical applications, the two types of processing operations described above can be flexibly combined or used independently according to on-site needs. Combined with real-time status monitoring during the stripping process, this invention forms a complete pre-treatment and post-treatment protection system. Real-time status monitoring prevents problems before they occur during stripping, while anomaly handling is performed precisely to remedy and correct parameters after stripping is complete. In some simplified implementations, only auxiliary ultrasonic treatment can be relied upon to handle minor residues, or if auxiliary ultrasonic treatment fails to meet the standard after multiple attempts, a manual intervention prompt is directly generated for review by professional testing personnel. This multi-branch closed-loop control logic completely eliminates settlement disputes caused by data inaccuracies in traditional constant-power ultrasonic stripping methods, making the entire non-destructive testing and pricing process highly automated and credible.

[0080] At the spot trading site for waste battery recycling, inspectors are monitoring the test results on the screen. Although a three-stage ultrasonic stripping and image verification process has been implemented, two troublesome anomalies occasionally occur during continuous testing. One is that the copper foil itself is not damaged, but a small amount of graphite adheres to the surface, resulting in slightly lower cleanliness; the other is that the edges of the copper foil are slightly curled or torn, causing the damage rate to exceed the standard. If such situations are immediately discarded and retested, or if inspectors are asked to manually adjust the machine parameters based on experience, it not only seriously delays the on-site trading time but also easily leads to inconsistent final results due to the subjectivity of human parameter adjustment. To address this, this invention proposes an anomaly handling mechanism with self-recovery and adaptive capabilities.

[0081] Further, in some preferred embodiments, the processing operation includes: when the physical damage rate meets a preset damage rate condition but the surface cleanliness does not meet a preset cleanliness condition, controlling the ultrasonic cleaning device to operate with an auxiliary ultrasonic processing power lower than the ultrasonic output power of the second stage; if the surface cleanliness obtained after operation still does not meet the preset cleanliness condition, then performing at least one of the following: adjusting the supplementary parameters applied to the auxiliary ultrasonic processing power or the duration of the auxiliary ultrasonic processing, or sending a liquid medium heating command to the liquid medium to increase the temperature of the liquid medium; and counting the number of attempts of operation and execution, and when the number of attempts reaches a preset maximum number of attempts and the surface cleanliness still does not meet the preset cleanliness condition, generating a manual intervention prompt message; when the physical damage rate does not meet the preset damage rate condition, generating a copper foil damage alarm message, discarding the current secondary quality, and determining a downward adjustment amount based on the physical damage rate, and applying the downward adjustment amount to the ultrasonic parameters of at least one stage in the subsequent ultrasonic peeling process of the sample electrode.

[0082] When the physical damage rate meets the preset damage rate condition but the surface cleanliness does not meet the preset cleanliness condition, it means that the physical structure of the copper foil itself is intact, with only trace amounts of graphite remaining on the surface. In this case, the ultrasonic cleaning device is controlled to assist the ultrasonic processing power. It is important to note that the auxiliary ultrasonic processing power here must be strictly lower than the ultrasonic output power of the second stage. This is because the graphite damping protective layer on the copper foil surface has essentially disappeared at this point. If the high power of the second stage is used, the intense cavitation impact will instantly exceed the bending yield limit of the ultra-thin copper foil, causing the originally intact copper foil to crack during the repair process. Specifically, the auxiliary ultrasonic processing power can be set to 100W and run for 5 seconds. The microjets generated by this power and time combination are just enough to wash away the loose trace amounts of graphite particles on the surface, while gently protecting the exposed copper foil substrate.

[0083] If the surface cleanliness obtained after operation still does not meet the preset cleanliness conditions, it indicates that the residual graphite may be adhered tightly due to incomplete dissolution of the binder. In this case, at least one of the following will be executed: adjusting the supplementary parameters applied to the auxiliary ultrasonic treatment power or the duration of the auxiliary ultrasonic treatment, or sending a liquid medium heating command to the liquid medium to increase its temperature. Specifically, the auxiliary ultrasonic treatment power can be slightly increased by 5W, or the duration can be extended by 3 seconds. More preferably, a liquid medium heating command is sent to the liquid medium to activate the micro-temperature heating module at the bottom of the cleaning tank, raising the temperature of the liquid medium to 30-35°C. The ingenuity of this heating operation lies in the fact that it improves cleaning efficiency from the perspective of chemical and physical penetration by reducing the liquid viscosity and accelerating the softening and dissolution of residual binder, thereby avoiding the risk of copper foil damage caused by simply increasing mechanical impact.

[0084] The system counts the number of attempts performed and executes the test. When the number of attempts reaches the preset maximum and the surface cleanliness still does not meet the preset cleanliness requirements, a manual intervention prompt is generated. Specifically, the preset maximum number of attempts can be set to 3. When this limit is reached, a prominent red prompt box will pop up on the screen, accompanied by a rapid beeping sound, reminding the inspection personnel to remove the sample for manual inspection. The reason for setting this limit is that if low-power ultrasonic treatment is repeated indefinitely, although the impact of each individual attack is small, the accumulated fatigue stress can still cause micro-cracks or even breakage in the ultra-thin copper foil. This limit mechanism maximizes the success rate of automated repair while safeguarding the structural safety of the copper foil.

[0085] When the physical damage rate fails to meet the preset damage rate condition, it means that the copper foil has suffered substantial physical damage, such as edge curling, central tearing, or cavitation pinholes. In this case, some copper foil fragments are very likely to have been lost with the water flow during the previous rinsing process, resulting in a significantly lower secondary quality. In response, a copper foil damage alarm will be generated and a warning will be displayed on the interface. Simultaneously, the current secondary quality will be discarded and will not be included in subsequent content calculations to prevent erroneous weight data from directly causing significant deviations in transaction pricing.

[0086] The adjustment amount is determined based on the physical damage rate and applied to the ultrasonic parameters of at least one stage in the ultrasonic ablation process of subsequent sample electrodes. It's important to explain why this adjustment is applied to subsequent samples. While the current sample is damaged and its data is no longer valuable, the damage itself conveys a crucial signal: the current batch of electrodes or the current combination of ultrasonic parameters is too aggressive. Specifically, the adjustment amount can be determined based on the specific value of the physical damage rate. For example, when the physical damage rate slightly exceeds the limit, the adjustment amount is set at 10W; when the physical damage rate severely exceeds the limit, the adjustment amount is set at 25W. This adjustment amount is then applied to the second-stage main ablation reference power of subsequently resampled sample electrodes, or the duration of a single unit of main ablation is shortened, or even the transition state threshold in real-time status determination is moved forward. Through this quantitative feedback based on the actual degree of damage, the intensity of ultrasonic peeling can adaptively converge to the safe range that the current batch of electrodes can withstand, effectively avoiding the chain reaction of repeated copper foil damage caused by the same set of aggressive parameters in subsequent continuous tests, and greatly improving the stability and data confidence of batch testing.

[0087] Furthermore, in some preferred methods, the transaction price of the waste negative electrode sheets is calculated based on the copper foil content and preset transaction parameters. After obtaining the accurate copper foil content of the batch of waste negative electrode sheets, the data processing terminal can further execute the transaction pricing step, seamlessly converting the quality inspection results into a fair and transparent price. Specifically, the preset transaction parameters include at least the total transaction weight of the batch of electrode sheets, the spot market price of metallic copper, and the market price of recycled graphite powder. These parameters can be manually entered by the operator in the graphical interface or automatically obtained from the market data interface via network connection. In terms of calculation logic, the pricing principle is to allocate the total price according to the mass proportion of the value components, that is, the total transaction price equals the sum of the value of copper and the value of graphite powder. The mathematical expression for the total transaction price P can be represented as follows: the total transaction weight P equals the total transaction weight m_total multiplied by the average percentage content of copper foil C_Cu_avg, then multiplied by the spot copper price P_Cu, then multiplied by the unit conversion factor K, plus the difference between the total transaction weight m_total multiplied by one and the average percentage content of copper foil C_Cu_avg, then multiplied by the market price of recycled graphite P_graphite, and finally multiplied by the unit conversion factor K. In actual code implementation, because the units of weight and price are often inconsistent in real-world transactions (e.g., total weight in kilograms while market price in yuan per ton), the data processing terminal introduces a preset unit conversion factor to eliminate the dimensional differences. For example, when the total weight is input in kilograms and the price is yuan per ton, the unit conversion factor K is set to one-thousandth. If the total weight is directly in tons, the factor K is adjusted to one.

[0088] This automated pricing model allows the data processing terminal to directly generate and display the suggested total transaction price. Simultaneously, it automatically generates a testing and pricing report containing information such as price, content, and cleanliness, serving as a settlement document for both parties. This method avoids errors that may arise from manual table lookups, calculations, and unit conversions, eliminating the need for complex additional calculation tools and significantly reducing settlement time. The entire testing-to-pricing process forms a complete closed loop, making the entire process from sample acquisition to quotation output highly automated, standardized, and traceable, thereby improving fairness and efficiency in spot trading.

[0089] In some specific implementations, see Figure 2The method includes the following steps. First, a sample electrode obtained from the waste electrode to be tested is provided, and the initial mass of the sample electrode is obtained. Before ultrasonic ablation, the material property parameters of the sample electrode can also be obtained, and ultrasonic parameters such as ultrasonic output power and duration for each subsequent stage are determined based on the material property parameters. Next, the sample electrode is immersed in a liquid medium for ultrasonic ablation. The ultrasonic ablation process includes at least a first stage, a second stage, and a third stage executed in chronological order. To match the ultrasonic output energy with the damping change during the removal of the graphite coating on the sample electrode surface, the ultrasonic output power in the first stage is lower than that in the second stage, and the ultrasonic output power in the third stage is also lower than that in the second stage. In the second stage of ultrasonic ablation, a first ablation state parameter reflecting the transmittance of the liquid medium and a second ablation state parameter reflecting the load impedance of the ultrasonic transducer can be obtained, and the graphite removal degree parameter and the damping change degree parameter can be determined accordingly. When these two parameters meet different preset conditions, the system will maintain the current ultrasonic output, reduce the ultrasonic output power, or directly terminate the second stage. Simultaneously, the system calculates the cumulative ultrasonic energy applied in the second stage. When the cumulative ultrasonic energy reaches the preset safe cumulative energy limit, the second stage terminates. Furthermore, if the sample electrode is determined to have entered a transitional state where graphite and bare copper coexist during the second stage, the ultrasonic output power of subsequent ultrasonic output units will be reduced, or the duration of subsequent ultrasonic output units will be shortened. After ultrasonic stripping, the stripped copper foil is removed from the liquid medium, its secondary mass is obtained, and a surface image of the copper foil is acquired. Subsequently, based on the image characteristics of the surface image, a first grayscale threshold and a second grayscale threshold are adaptively determined. These two thresholds are used to segment the graphite residue area and the physical damage area in the surface image, thereby obtaining the surface cleanliness characterizing the degree of graphite residue and the physical damage rate characterizing the degree of copper foil damage. Next, a conditional judgment is performed. When the surface cleanliness meets the preset cleanliness condition and the physical damage rate meets the preset damage rate condition, the secondary mass is taken as the effective secondary mass, and the copper foil content of the sample electrode is calculated based on the effective secondary mass and the initial mass. Finally, based on the calculated copper foil content and preset trading parameters, the trading price of the waste negative electrode is calculated. If the surface cleanliness does not meet the preset cleanliness condition, or the physical damage rate does not meet the preset damage rate condition, the corresponding processing operation is performed. Specifically, when the physical damage rate meets the preset damage rate condition but the surface cleanliness does not meet the preset cleanliness condition, the ultrasonic cleaning device is controlled to operate at an auxiliary ultrasonic processing power lower than the second-stage ultrasonic output power to remove residual graphite. If the surface cleanliness obtained after operation still does not meet the conditions, supplementary parameters can be adjusted to the auxiliary ultrasonic processing power or the duration of the auxiliary ultrasonic processing, or a heating command can be sent to the liquid medium to increase the temperature of the liquid medium.The system counts the number of attempts during operation and execution. When the number of attempts reaches the preset maximum and the surface cleanliness still does not meet the requirements, a manual intervention prompt is generated. When the physical damage rate does not meet the preset damage rate condition, a copper foil damage alarm is generated, the current secondary quality is discarded, and an adjustment amount is determined based on the physical damage rate. This adjustment amount is then applied to the relevant ultrasonic parameters in the subsequent ultrasonic peeling process of the sample electrode.

[0090] As a practical application of the present invention in a production scenario, parallel testing was conducted using the same batch of unfilled waste graphite negative electrode sheets. This batch of sample electrode sheets was produced by a lithium-ion battery manufacturer. The sample electrode sheets include a copper foil substrate and a graphite coating attached to the surface of the copper foil substrate. The binder used in the graphite coating is PVDF.

[0091] In this embodiment, the operator randomly cuts three 3cm × 5cm sample electrodes from different locations in the batch of waste negative electrode sheets to be tested (see...). Figure 3 Three sample electrode sheets were placed in a forced-air drying oven and dried at 105℃±5℃ for 60±5 min, then transferred to a desiccator to cool to room temperature. Subsequently, the initial mass m1 of the three sample electrode sheets was obtained using an analytical balance with an accuracy of 0.1 mg. The initial masses m1 of the three sample electrode sheets were 20.1543 g, 19.8876 g, and 20.4451 g, respectively.

[0092] Then, the three sample electrodes were completely immersed in a liquid medium formed by deionized water and subjected to ultrasonic peeling treatment using an ultrasonic cleaning device. This ultrasonic peeling treatment included at least three stages executed sequentially in time: a first stage, a second stage, and a third stage. In this embodiment, the first stage was the immersion initiation stage, with an ultrasonic output power of 120W and a duration of 20 seconds; the second stage was the main peeling stage, with an ultrasonic output power of 200W and a duration of 40 seconds; and the third stage was the cleaning and consolidation stage, with an ultrasonic output power of 150W and a duration of 10 seconds. Through the aforementioned phased ultrasonic output, the ultrasonic output energy was matched to the damping changes during the graphite coating peeling process on the sample electrode surface, thereby promoting graphite coating peeling while reducing the risk of curling, tearing, or pinhole damage to the exposed copper foil due to continuous high-power cavitation impact.

[0093] After ultrasonic stripping, the operator removes the stripped copper foil from the liquid medium and gently rinses the surface with deionized water to remove loosely attached graphite particles. The copper foil is then placed in a forced-air drying oven and dried at 105℃±5℃ for 60±5 min, before being transferred to a desiccator to cool to room temperature, yielding copper foil with the graphite coating removed. See [link to relevant documentation]. Figure 4The secondary mass m2 of three copper foil samples was obtained using the same analytical balance. The secondary masses m2 of the three copper foil samples were 4.2152 g, 4.1568 g, and 4.3589 g, respectively.

[0094] After obtaining the secondary mass m2, three surface images of the copper foil were further acquired. Specifically, the dried copper foil was placed under standard lighting conditions, and high-resolution images of the front and back sides of the copper foil were acquired respectively, and the surface images were transmitted to the data processing terminal. The data processing terminal performed grayscale conversion, contrast enhancement, and noise filtering on the surface images, and performed region segmentation based on image features to identify graphite residue areas, clean copper foil areas, and physically damaged areas from the surface images. Based on the region segmentation results, the surface cleanliness of the three copper foils was calculated, and it was determined whether the physical damage rate met the preset damage rate condition.

[0095] Image analysis revealed that the surface cleanliness (Sc) of the three copper foil samples were 99.7%, 99.8%, and 99.6%, respectively, all meeting the preset cleanliness requirements. Furthermore, no tearing, pinhole, or gap areas were identified in the surface images of the three copper foil samples that would cause the physical damage rate to fail to meet the preset damage rate requirements. Therefore, it was determined that the physical damage rate of all three copper foil samples met the preset damage rate requirements. Consequently, the data processing terminal marked the secondary mass (m2) of the three copper foil samples as the effective secondary mass.

[0096] The data processing terminal calculates the copper foil content of each sample electrode based on the effective secondary mass and the initial mass. Specifically, the copper foil content C_Cu of the sample electrode is calculated according to the following formula: C_Cu=m2 / m1×100%; For the first sample electrode, the copper foil content is: 4.2152 / 20.1543 × 100% = 20.91%; For the second sample electrode, the copper foil content is: 4.1568 / 19.8876 × 100% = 20.90%; For the third sample electrode, the copper foil content is: 4.3589 / 20.4451×100%=21.32%; Therefore, the average copper foil content C_Cu_avg of this batch of waste negative electrode sheets is: C_Cu_avg=(20.91%+20.90%+21.32%) / 3=21.04%; The relative standard deviation (RSD) of the three parallel samples was approximately 1.1%, indicating that the copper foil content detection results obtained using the m² method of this invention have good repeatability and stability.

[0097] Specifically, the data processing terminal calculates the transaction price of this batch of waste negative electrode sheets based on the aforementioned copper foil content and preset transaction parameters. The preset transaction parameters include the total mass m_total of this batch of waste negative electrode sheets, the spot price of copper P_Cu, and the market price of recycled graphite P_Graphite. The transaction price P is calculated according to the following formula: P = m_total × C_Cu_avg × P_Cu × 10 -3 +m_total×(1-C_Cu_avg)×P_Graphite×10 -3 ; Where m_total is in kg, and P_Cu and P_Graphite are in yuan / ton, 10 -3 Used for unit conversion. When C_Cu_avg is expressed as a percentage, it is converted to decimal form before being used in calculations.

[0098] In this embodiment, the total mass m_total of the batch of waste negative electrode sheets is set to 1000 kg, the spot price of copper P_Cu on that day is 70,000 yuan / ton, and the market price of recycled graphite powder P_Graphite is 4,000 yuan / ton. Converting the average copper foil content C_Cu_avg = 21.04% to 0.2104 and substituting it into the above formula, we obtain: The value of copper is comprised of: 1000×0.2104×70000×10 -3 =14,728 yuan; The value of graphite is partly due to: 1000×(1-0.2104)×4000×10 -3 ≈3158.4 yuan; Therefore, the transaction price P for this batch of waste negative electrode sheets is approximately: 14728 + 3158.4 = 17886.4 yuan; Therefore, the data processing terminal can generate a testing and pricing report based on the initial mass m1, effective secondary mass m2, surface cleanliness Sc, physical damage rate assessment result, copper foil content C_Cu, and preset trading parameters. This report includes sample information, the initial mass m1 of each sample electrode, the effective secondary mass m2 of each copper foil, the copper foil content of each sample electrode, the average copper foil content of the batch of waste negative electrode sheets, surface images and their region segmentation results, surface cleanliness, physical damage rate assessment result, preset trading parameters, and the finally calculated trading price. In this way, the testing results are no longer just single weighing data, but form a testing and pricing basis composed of mass data, image verification results, and trading prices, which can improve the objectivity and traceability of spot trading pricing for waste negative electrode sheets.

[0099] Specifically, the same batch of sample electrodes was used for comparative testing. The only difference between this comparative testing and the above implementation method is that the ultrasonic stripping process uses a constant power ultrasonic method, that is, the ultrasonic output power is fixed at 180W and the duration is 60s. The other steps of sampling, drying, initial weighing, secondary weighing of copper foil, surface image acquisition, region segmentation, surface cleanliness calculation and copper foil content calculation are the same as those in the above implementation method.

[0100] The test results showed that under constant power ultrasonication, the peeled copper foil exhibited slight curling, and some areas of the copper foil showed pinholes or localized damage in the image analysis, indicating that its physical damage rate was higher than that of the m2-stage ultrasonic peeling method of this invention. Simultaneously, the average surface cleanliness (Sc) obtained from image analysis was approximately 99.2%, lower than the preset cleanliness condition, and some areas still showed graphite accumulation residue. This indicates that the constant power ultrasonication method maintains a high ultrasonic output power in the later stages of peeling, easily subjecting the exposed copper foil to strong cavitation impacts, leading to copper foil damage; at the same time, graphite residue may remain in some un-detached areas, causing the secondary quality to be affected by both copper foil loss and graphite residue. Calculations showed that the copper foil content test results of the three parallel samples fluctuated significantly, with a relative standard deviation (RSD) of approximately 2.8%, higher than the RSD when using the m2 method of this invention. These results demonstrate that this invention, by adjusting the ultrasonic output power in stages and combining it with surface image verification to screen effective secondary quality, can improve the stability and reliability of copper foil content determination.

[0101] Specifically, the transaction price was estimated using the same batch of waste negative electrode sheets. Traditional empirical estimation methods do not perform the aforementioned non-destructive testing on the sample electrode sheets; instead, they estimate the copper foil content based on the nominal size, nominal coating amount, and empirical loss coefficient of the electrode sheets. In this comparative example, the empirical loss coefficient is taken as 0.92, and the estimated copper foil content of this batch of waste negative electrode sheets is approximately 19.5%.

[0102] Compared to the average copper foil content of 21.04% obtained using the m2 method of this invention, the estimation result obtained by the traditional empirical method has an absolute deviation of 1.54 percentage points. Given that the total mass of this batch of waste negative electrode sheets is 1000 kg and the spot price of copper is 70,000 yuan / ton, the difference in copper value caused solely by the deviation in copper foil content is: 1000×(21.04%-19.5%)×70000×10 -3 =1078 yuan; Therefore, traditional empirical estimation methods lack objective testing evidence of the true copper foil content of sample electrodes, easily leading to discrepancies in the perceived value of the goods between the transacting parties. This invention, through staged ultrasonic stripping, image verification, effective secondary quality screening, and transaction price calculation, can convert the actual copper foil content of sample electrodes into a verifiable transaction price, thereby reducing transaction settlement disputes caused by testing errors or empirical estimation deviations.

[0103] See Figure 2 The present invention also proposes a non-destructive testing and pricing system for the trading and pricing of waste lithium-ion battery negative electrode sheets, including a data processing terminal, an ultrasonic cleaning device, a weighing device, and an image acquisition device. The data processing terminal is configured to execute any of the above-mentioned method steps.

[0104] The above solution utilizes a data processing terminal as the core control and data processing center, and interacts with ultrasonic cleaning devices, weighing devices, and image acquisition devices to achieve fully automated control of the entire process from physical stripping, mass weighing, image verification to final pricing output. This effectively solves the problems of separation of various testing steps in spot trading, human error caused by manual weighing and manual data entry, data inconsistency, and low testing efficiency. It significantly improves the automation level and test reproducibility of the testing process, thereby providing both parties in spot trading with credible and tamper-proof price certificates.

[0105] The above description is merely an embodiment of the present invention and is not intended to limit the scope of protection of the present invention. For those skilled in the art, the present invention can have various modifications and variations. All modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A non-destructive testing method for pricing the trading of waste lithium-ion battery negative electrode sheets, characterized in that... Includes the following steps: S1. Provide a sample electrode obtained from the waste electrode to be tested, and obtain the initial mass of the sample electrode; S2. Immerse the sample electrode in a liquid medium and perform ultrasonic ablation treatment. The ultrasonic ablation treatment includes at least a first stage, a second stage, and a third stage executed in chronological order. The ultrasonic output power of the first stage is lower than that of the second stage, and the ultrasonic output power of the third stage is lower than that of the second stage, so that the ultrasonic output energy matches the damping change during the removal of the graphite coating on the surface of the sample electrode. S3. Remove the stripped copper foil from the liquid medium and obtain the secondary mass of the copper foil; S4. Obtain a surface image of the copper foil; S5. Perform region segmentation on the surface image to obtain the surface cleanliness, which characterizes the degree of graphite residue, and the physical damage rate, which characterizes the degree of copper foil damage; S6. When the surface cleanliness meets the preset cleanliness condition and the physical damage rate meets the preset damage rate condition, the secondary mass is taken as the effective secondary mass, and the copper foil content of the sample electrode is calculated based on the effective secondary mass and the initial mass.

2. The non-destructive testing method for pricing waste lithium-ion battery negative electrode sheets according to claim 1, characterized in that: Prior to the ultrasonic ablation process, the procedure also includes: Obtain the material property parameters of the sample electrode; Based on the material property parameters, the ultrasonic parameters for the first stage, the ultrasonic parameters for the second stage, and the ultrasonic parameters for the third stage are determined, wherein the ultrasonic parameters include at least ultrasonic output power and duration.

3. The non-destructive testing method for pricing waste lithium-ion battery negative electrode sheets according to claim 1, characterized in that: The second stage of ultrasonic ablation includes: At least one peeling state parameter is obtained, the peeling state parameter reflecting the peeling state of the sample electrode in the liquid medium; The ultrasonic output of the second stage is adjusted according to the stripping state parameters.

4. The non-destructive testing method for pricing waste lithium-ion battery negative electrode sheets according to claim 3, characterized in that: In the second stage, at least one ablation state parameter is acquired, and the ultrasound output of the second stage is adjusted according to the ablation state parameter, including: A first stripping state parameter of the liquid medium and a second stripping state parameter of the ultrasonic transducer are obtained. The first stripping state parameter reflects the light transmittance of the liquid medium, and the second stripping state parameter reflects the load impedance of the ultrasonic transducer. Based on the first peeling state parameter, determine the graphite shedding degree parameter; Based on the second peeling state parameters, determine the damping change parameter; When the graphite shedding degree parameter and the damping change degree parameter meet the first preset condition, the current ultrasonic output of the second stage is maintained; When the graphite shedding degree parameter or the damping change degree parameter meets the second preset condition, the ultrasonic output power of the second stage is reduced. The second stage terminates when the graphite shedding degree parameter or the damping change degree parameter meets the third preset condition.

5. The non-destructive testing method for pricing waste lithium-ion battery negative electrode sheets according to claim 3, characterized in that: The second-stage ultrasonic ablation process includes multiple ultrasonic output units, and the method further includes: Obtain the unit ultrasound output parameters of the plurality of ultrasound output units; Based on the unit's ultrasonic output parameters, calculate the cumulative ultrasonic energy value applied in the second stage; Obtain the preset safe cumulative energy limit; The second stage terminates when the cumulative ultrasonic energy value reaches the safe cumulative energy limit. Furthermore, in the second stage, when the sample electrode is determined to have entered a transitional state where graphite and bare copper coexist, based on the peeling state parameters, the ultrasonic output power of the subsequent ultrasonic output unit is reduced, and / or the duration of the subsequent ultrasonic output unit is shortened.

6. The non-destructive testing method for pricing waste lithium-ion battery negative electrode sheets according to claim 1, characterized in that: Performing region segmentation on the surface image includes: Based on the image features of the surface image, a first grayscale threshold and a second grayscale threshold are adaptively determined; Based on the first grayscale threshold and the second grayscale threshold, the graphite residue area and the physical damage area are segmented in the surface image.

7. The non-destructive testing method for pricing waste lithium-ion battery negative electrode sheets according to claim 1, characterized in that: The method further includes: When the surface cleanliness does not meet the preset cleanliness condition, or the physical damage rate does not meet the preset damage rate condition, the corresponding processing operation is performed for the non-compliance situation. The processing operation includes at least one of the following: Auxiliary ultrasonic treatment is performed at a lower ultrasonic output power than in the second stage to remove residual graphite; Discard the current secondary mass and adjust the ultrasonic parameters in at least one stage of the subsequent ultrasonic ablation process of the sample electrode according to the physical damage rate.

8. The non-destructive testing method for pricing waste lithium-ion battery negative electrode sheets according to claim 7, characterized in that: The processing operations include: When the physical damage rate meets the preset damage rate condition and the surface cleanliness does not meet the preset cleanliness condition, the ultrasonic cleaning device is controlled to operate with auxiliary ultrasonic processing power, which is lower than the ultrasonic output power of the second stage. If the surface cleanliness obtained after the operation still does not meet the preset cleanliness condition, then at least one of the following is performed: adjust the supplementary parameter applied to the auxiliary ultrasonic power or the duration of the auxiliary ultrasonic treatment, or send a liquid medium heating command to the liquid medium to increase the temperature of the liquid medium; The number of attempts for the operation and execution is counted. When the number of attempts reaches the preset maximum number of attempts and the surface cleanliness still does not meet the preset cleanliness condition, a manual intervention prompt message is generated. When the physical damage rate does not meet the preset damage rate condition, a copper foil damage alarm is generated, the current secondary quality is discarded, and a downward adjustment amount is determined based on the physical damage rate. The downward adjustment amount is then applied to the ultrasonic parameters of at least one stage in the ultrasonic peeling process of the subsequent sample electrode.

9. A non-destructive testing method for pricing waste lithium-ion battery negative electrode sheets according to claim 1, characterized in that: The method further includes: The transaction price of the waste negative electrode sheet is calculated based on the copper foil content and preset transaction parameters.

10. A non-destructive testing and pricing system for the trading and pricing of waste lithium-ion battery negative electrode sheets, characterized in that: The system includes: a data processing terminal, an ultrasonic cleaning device, a weighing device, and an image acquisition device; the data processing terminal is configured to perform the steps of the non-destructive testing method as described in any one of claims 1 to 9.

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