A dry electrode film roll pressing method and a dry electrode film roll pressing apparatus

Abstract

The application discloses a dry electrode film roll pressing and compounding method and a dry electrode film roll pressing device, and the method comprises the following steps: leading a current collector film out from a non-powered unwinding shaft and making the current collector film form a hanging arc by gravity, and then passing through a first roll gap; synchronously unwinding two dry electrode films by non-power, and making the two dry electrode films enter the first roll gap in a self-suspended state and be double-sidedly attached to the current collector film to form an initial compound; wrapping an isolation film on the outside of the initial compound to obtain a to-be-heated compound, and making the to-be-heated compound enter a second roll gap in a self-suspended state; performing hot pressing compounding on the to-be-heated compound by a compounding roller on the two sides of the second roll gap; and then peeling off the isolation film and winding the double-sided dry electrode. The method utilizes natural suspension to realize near-zero tension conveying, cooperates with the isolation film wrapping and the hot pressing roller one-time double-sided pressing, can effectively avoid the edge micro-cracks and the whole width breakage of the dry electrode film, and improves the interface density and the yield of the roll-to-roll production.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery electrode preparation technology, and in particular to a dry electrode film roll forming method and dry electrode film roll forming equipment. Background Technology

[0002] Dry-process electrode films are lithium-ion battery electrode materials prepared using a solvent-free process. In this process, active materials (such as lithium iron phosphate, ternary materials, and graphite), conductive agents (such as carbon black and carbon nanotubes), and binders (such as polytetrafluoroethylene (PTFE) and aramid fibers) are mixed in a specific ratio and then directly formed into a self-supporting film with a certain mechanical strength through mechanical pressing. Compared with traditional wet processes, the dry-process electrode film preparation avoids the use of organic solvents, eliminates solvent recovery and drying steps, and has significant advantages such as simplified process, environmental friendliness and energy saving, and high production efficiency. It also allows for the preparation of thicker electrode layers, effectively improving the energy density of the battery.

[0003] In existing technologies, the composite process of dry electrode films and current collectors typically employs a roll-to-roll hot-pressing method. The basic process involves: the dry electrode film is pulled and unfolded using an actively driven unwinding device, then bonded to a metal current collector film (aluminum or copper foil) under a certain tension, and subsequently directly fed into a heated composite roller for hot-pressing. However, in actual production, due to the relatively brittle nature of the dry electrode film material and the uneven internal stress distribution after pressing, the traditional active unwinding method is prone to tension fluctuations during start-up, shutdown, and speed changes. This can induce micro-cracks, pulverization, or even full-width strip breakage at the film edges, affecting the performance stability and yield of the electrode products. Summary of the Invention

[0004] The main objective of this invention is to solve the technical problems of edge micro-cracks, powdering, and uneven interface bonding caused by fluctuations in active unwinding tension in existing dry electrode film roll-to-roll composite processes.

[0005] The first aspect of this invention provides a dry electrode film roll forming method, the dry electrode film roll forming method comprising:

[0006] The current collector membrane is drawn out from the unpowered unwinding shaft, allowing it to form a hanging arc under its own weight and enter the first roller gap;

[0007] Two dry electrode films are unwound synchronously without power, so that each dry electrode film enters the first roller gap by its own weight, and the two dry electrode films are attached to the current collector film by the hanging state formed by their own weight, thus obtaining an initial composite.

[0008] An isolation film is wrapped around the two outer sides of the initial composite to obtain the composite to be heated, and the composite to be heated is made into a hanging arc before entering the second roller gap;

[0009] The composite to be heated is hot-pressed and bonded by the composite rollers on both sides of the second roller gap;

[0010] The double-sided dry electrode sheet is peeled off and then wound up after lamination.

[0011] Preferably, the dry electrode film roll forming method further includes:

[0012] During the bonding process between the dry electrode membrane and the current collector membrane, the quantity and / or quality information of solid particles that detach from the dry electrode membrane due to bonding are acquired in real time to generate a first detection signal characterizing the quality of the bonding interface.

[0013] The first detection signal is compared with a preset threshold to obtain the interface quality deviation.

[0014] Based on the interface quality deviation, at least one bonding process parameter is dynamically adjusted. The bonding process parameter includes at least one of the following: first roller gap width, bonding roller linear pressure, unwinding shaft damping torque, overhang arc length, and roll material linear speed, so as to maintain or restore the bonding interface quality to the target range.

[0015] Preferably, the real-time acquisition of the quantity and / or quality information of solid particles detached from the self-drying electrode film due to bonding, in order to generate a first detection signal characterizing the bonding interface quality, includes:

[0016] Within the sampling time window of continuous production, the cumulative mass increment of detached particles is obtained, and combined with the vertical offset of the particle flight path, the inertial stability of the detached particles is determined, thus obtaining the first parameter characterizing the particle detachment characteristics.

[0017] Within the same time window, the concentration and continuous shift trend of the falling particles along the width of the membrane are analyzed to identify whether the particles are accumulated in the edge area of ​​the membrane for a long time, thus obtaining a second parameter characterizing the bonding consistency.

[0018] According to the front, middle and rear sections of the bonding process along the winding direction, the changing trend of the number of detached particles in each stage is statistically analyzed to determine the evolutionary stability of the bonding interface and obtain the third parameter.

[0019] The first parameter, the second parameter, and the third parameter are integrated to generate a first detection signal representing the quality status of the bonding interface.

[0020] Preferably, within the sampling time window of continuous production, the cumulative mass increment of detached particles is obtained, and combined with the vertical offset of the particle flight path, the inertial stability of the detached particles is determined to obtain a first parameter characterizing the particle detachment characteristics, including:

[0021] The cumulative mass increment of the sampling time window is obtained by summing the individual particle masses of all detached particles detected within the sampling time window.

[0022] According to the preset single particle mass threshold, the detached particles are divided into heavy particle group and light particle group;

[0023] Based on the mass of a single particle in the heavy-mass particle group and the light-mass particle group respectively, the vertical offset of the corresponding particles is averaged by mass weight to obtain the mean offset of the heavy-mass particle group and the mean offset of the light-mass particle group.

[0024] The inertial stability index is determined by using the cumulative mass increment, the proportion of heavy particles, the average heavy mass offset, and the average light mass offset, and the inertial stability index is used as the first parameter.

[0025] Preferably, the step of analyzing the concentration and continuous shift trend of the detached particles along the width direction of the membrane material within the same time window, and identifying whether the particles have been accumulating in the edge area of ​​the membrane material for a long time, to obtain a second parameter characterizing the adhesion consistency, includes:

[0026] Within the same sampling time window, the landing points of the detached particles are divided into equal-width sections according to the width of the membrane material. The number of particles in each section is counted and the proportion of particles in the edge area to the total number of particles in the whole membrane is calculated.

[0027] Within several adjacent sampling time windows, an autoregressive calculation is performed on the proportion of the edge region to obtain the edge bias persistence coefficient;

[0028] A fitting consistency index is generated based on the edge area ratio and the edge offset persistence coefficient, and the fitting consistency index is used as the second parameter.

[0029] Preferably, the step of statistically analyzing the changing trend of particle detachment at each stage according to the front, middle, and rear sections along the rolling direction of the bonding process, and determining the evolutionary stability of the bonding interface to obtain the third parameter includes:

[0030] Within a continuous sampling time window, the sampling time window is divided into a front section, a middle section, and a rear section according to the direction of roll-in. The number of detached particles in each section is accumulated to obtain the number of particles in the front section, the number of particles in the middle section, and the number of particles in the rear section.

[0031] The front-to-middle section attenuation rate is calculated based on the number of particles in the front section and the number of particles in the middle section, and the middle-to-rear section attenuation rate is calculated based on the number of particles in the middle section and the number of particles in the rear section.

[0032] The attenuation rates of the front-middle section and the middle-rear section are weighted and combined to generate a bonding evolution stability index, which is then used as the third parameter.

[0033] Preferably, the step of comparing the first detection signal with a preset threshold to obtain the interface quality deviation includes:

[0034] Within each sampling time window, the first detection signal is normalized according to the winding speed to obtain a speed-normalized signal;

[0035] Based on the edge offset duration coefficient of the time window corresponding to the velocity normalization signal, the preset benchmark threshold is corrected to generate a dynamic threshold.

[0036] The speed-normalized signal is compared with the dynamic threshold to obtain the instantaneous deviation value;

[0037] Within a preset roll length section, calculate the section average deviation for continuous instantaneous deviation values;

[0038] The interface quality deviation is generated based on the instantaneous deviation value and the average deviation of the section.

[0039] Preferably, the step of correcting the preset reference threshold based on the edge offset duration coefficient of the time window corresponding to the velocity normalization signal to generate a dynamic threshold includes:

[0040] The edge offset duration coefficient of the sampling time window corresponding to the velocity normalized signal is used as the first correction factor to make the first correction to the preset benchmark threshold.

[0041] The threshold after the first correction is corrected a second time based on the fitting evolution stability index of the time window corresponding to the edge bias duration coefficient.

[0042] Based on the temperature range of the current production environment, the temperature range coefficient is retrieved, and the threshold after the second correction is adjusted for temperature to obtain the dynamic threshold.

[0043] Preferably, the step of dynamically adjusting at least one bonding process parameter based on the interface quality deviation, wherein the bonding process parameter includes at least one of the following: first roll gap width, bonding roll line pressure, unwinding shaft damping torque, overhang arc length, and roll material linear speed, to maintain or restore the bonding interface quality to the target range, includes:

[0044] The amplitude, direction, and duration of the interface quality deviation within the current sampling time window are classified, determined, and calculated to identify the main cause of the deviation.

[0045] Based on the main cause of the deviation, the bonding process parameters to be adjusted are selected. When the main cause of the deviation is edge shearing, the opposite side overhang arc length and unwinding shaft damping torque are selected. When the main cause of the deviation is center bulging, the first roller gap width and bonding roller line pressure are selected. When the main cause of the deviation is full-width pulverization, the roll material line speed is selected.

[0046] The selected bonding process parameters are adjusted according to the preset adjustment range;

[0047] During the subsequent verification sampling time window, monitor the interface quality deviation. If the deviation still exceeds the target range, repeat the process of determining the main cause, selecting parameters, and adjusting until the deviation returns to the target range.

[0048] A second aspect of the present invention provides a dry electrode film rolling equipment, wherein the dry electrode film rolling equipment employs the dry electrode film rolling composite method of any of the above embodiments.

[0049] The technical solution provided in this application embodiment involves a current collector belt that rotates freely on a powerless unwinding shaft. After being drawn down, it forms a drooping arc under its own weight, and the tension of the roll material is maintained at an extremely low level by the balance between its own weight and damping. Two self-supporting dry electrode films also droop under their own weight, passing through the same drooping arc area and entering the adjustable roller gap simultaneously with the current collector belt, where they are double-sided aligned and bonded. Gravity suspension provides flexible buffering for the material belt, and starting, stopping, or slight speed disturbances will not superimpose instantaneous tensile waves inside the film material. The edge fibers are no longer subjected to shear overload, and the initial locking is completed by applying low linear pressure to the flexible rollers at the moment of bonding. Subsequently, after being covered with a release film on both sides, the entire assembly passes through a controlled temperature and pressure roller gap. The release film isolates the high-temperature roller surface, evenly distributes the normal compressive stress, and avoids the adhesion of active powder. During the roller-to-roll contact time, the fibrous binder is in the softening-rearrangement zone, and the microfiber network is embedded into and bundled into the roughened metal surface under the combined action of pressure and temperature. The interface pores are compacted without generating new tensile concentration. After the separator membrane detaches from the laminate, it is wound up, and the double-sided electrode sheet is wound up under low tension. No additional traction torque is applied throughout the entire process. By using gravity suspension to reduce the impact of axial inertia, and in conjunction with the hot pressing of the separator membrane to achieve densification, micro-cracks and powdering no longer occur at the edges of the membrane material. The entire electrode sheet maintains a continuous, stable, and uniform bonding interface during the high-speed roll-to-roll process, fundamentally eliminating the problems of tape breakage and interface unevenness caused by tension fluctuations during active unwinding. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0051] Figure 1 This is a schematic diagram of one embodiment of the dry electrode film roll forming method in this invention;

[0052] Figure 2 This is a schematic diagram of another embodiment of the dry electrode film roll forming method in this invention;

[0053] Figure 3 This is a schematic diagram of the structure of an embodiment of the dry electrode film rolling equipment of the present invention;

[0054] Figure 4 for Figure 3 The schematic diagram of the dry electrode film rolling equipment in the image is shown with some parts omitted.

[0055] Explanation of icon numbers:

[0056] 10. Machine body; 11. Current collector unwinding; 12. First guide roller; 13. First dry film unwinding; 14. Second dry film unwinding; 15. First roller gap; 16. First separator unwinding; 17. Second separator unwinding; 18. Second guide roller; 19. Third guide roller; 20. First composite roller; 21. Second composite roller; 22. Second roller gap; 23. First separator winding; 24. Second separator winding; 25. Dry electrode winding; 26. Fourth guide roller; 27. Fifth guide roller; 28. Collector tray; 100. Current collector membrane; 200. Dry electrode membrane; 300. Separator membrane; 400. Dry electrode.

[0057] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0058] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0059] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0060] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the term "and / or" throughout the text includes three solutions; taking A and / or B as an example, it includes technical solution A, technical solution B, and a technical solution that simultaneously satisfies A and B. Furthermore, the technical solutions of various embodiments can be combined with each other, provided that they are feasible for those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0061] One embodiment of this application provides a dry electrode film roll forming method. This dry electrode film roll forming method is applied to dry electrode film roll forming equipment. Please refer to [link to relevant documentation]. Figure 3 and Figure 4 In one embodiment of this application, the dry electrode film rolling equipment includes a machine body 10 and structures mounted on the machine body 10 such as a current collector unwinding 11, a first guide roller 12, a first dry film unwinding 13, a second dry film unwinding 14, a first separator film unwinding 16, a second separator film unwinding 17, a second guide roller 18, a third guide roller 19, a first composite roller 20, a second composite roller 21, a first separator film winding 23, a second separator film winding 24, a dry electrode film winding 25, a fourth guide roller 26, a fifth guide roller 27, and a collection tray 28.

[0062] The current collector unwinding 11 is fitted with a current collector film 100. The current collector unwinding 11 adopts a non-powered unwinding structure. By guiding the current collector film 100 to the first guide roller 12, the film hangs down naturally under its own weight to form a hanging arc. Then it passes through the first roller gap 15 defined by the first dry film unwinding 13 and the second dry film unwinding 14, then through the guide space formed by the second guide roller 18 and the third guide roller 19, then through the second roller gap 22 formed by the first composite roller 20 and the second composite roller 21, and finally through the guide space between the fourth guide roller 26 and the fifth guide roller 27 and is recovered by the dry electrode winding 25.

[0063] Dry electrode films 200 are fitted onto both the first dry film unwinding 13 and the second dry film unwinding 14. The two dry electrode films 200 are led out into the first roller gap 15. At this time, the dry electrode film 200 led out by the first dry film unwinding 13 is located on one side of the current collector film 100, while the dry electrode film 200 led out by the second dry film unwinding 14 is located on the other side of the current collector film 100. The two dry electrode films 200 also form a suspended arc state under their own weight. In some embodiments, the width of the first roller gap 15 can be adjusted by horizontally moving the first dry film unwinding 13 or the second dry film unwinding 14 (e.g., by means of a motor, cylinder, lead screw drive, or manual drive). Simultaneously, a pressure sensor or position sensor can be configured to monitor the bonding pressure and positional accuracy, thereby enabling the two dry electrode films 200 to achieve gentle bonding with the corresponding surfaces of the current collector film 100 under controllable low linear pressure. In other embodiments, the dry electrode film 200 may not be bonded to the current collector film 100 at the first roller gap 15. Instead, when the three layers of material (two dry electrode films 200 sandwiching the current collector film 100) enter the second roller gap 22 together, the relative position and gap width of the first composite roller 20 relative to the second composite roller 21 are adjusted to achieve synchronous bonding between the dry electrode film 200 and the current collector film 100.

[0064] Both the first composite roller 20 and the second composite roller 21 are equipped with heating structures, such as heating tubes, heating lamps, resistance wires, hot water channels, or heat-conducting oil channels. The temperature control range is typically 80-200℃, with the specific temperature determined based on the melting characteristics of the binder in the dry electrode film 200. The surface of the composite rollers can be made of materials such as stainless steel, chrome plating, or ceramic coating to provide good thermal conductivity and wear resistance.

[0065] Both the first separator unwinding 16 and the second separator unwinding 17 are fitted with separator films 300. These separator films 300 are typically made of polyimide, polytetrafluoroethylene, or other high-temperature resistant materials. They protect the dry electrode film 200, preventing it from directly contacting and adhering to the high-temperature surfaces of the first composite roller 20 or the second composite roller 21. The operating temperature range of the separator film 300 should be at least higher than the operating temperatures of the first composite roller 20 and the second composite roller 21 to ensure structural integrity throughout the hot pressing process. After covering the initial composite, the separator film 300 passes through the second roller gap 22 along with the composite to be heated. Upon completion of the composite process, it is immediately peeled off at the roller gap exit and recycled by the first separator film winding 23 and the second separator film winding 24, respectively, achieving recycling and reducing production costs. The final dry electrode sheet 400 is then recycled by the dry electrode sheet winding 25.

[0066] In addition, a collection tray 28 is provided at the bottom of the first dry film unwinding 13 and the second dry film unwinding 14 for collecting particles that have detached from the dry electrode film 200. The collection tray 28 can prevent the falling particles from affecting the normal use of the bottom first composite roller 20, second composite roller 21 and other structures.

[0067] Traditional dry electrode film unwinding processes typically employ an active drive method, where a servo motor or variable frequency motor drives the unwinding shaft to rotate, actively controlling the unwinding speed and tension of the dry electrode film. This active drive mode requires a precise tension control system to coordinate the synchronization of the dry electrode film and the current collector film. However, due to the relatively brittle nature of the dry electrode film material and the uneven internal stress distribution after pressing, start-stop impacts, speed changes, or tension fluctuations during the active drive process can easily induce micro-cracks, powdering, or even film breakage at the film edges. Furthermore, synchronization errors between multiple active drive shafts can also lead to relative displacement between materials, affecting the bonding quality.

[0068] Therefore, this application proposes a dry electrode film roll forming method. Please refer to [link to relevant documentation]. Figure 1 The method includes the following steps:

[0069] The current collector membrane is drawn out from the unwinding shaft without power, allowing it to form a drooping arc under its own weight and enter the first roller gap. Simultaneously, two dry electrode membranes are unwound without power, allowing each dry electrode membrane to enter the first roller gap under its own weight, with both dry electrode membranes adhering to the current collector membrane under their own weight to obtain an initial composite. A separator film is then wrapped around the two outer sides of the initial composite to obtain a composite to be heated, which forms a drooping arc before entering the second roller gap. The composite to be heated is then hot-pressed onto the composite through the composite rollers on both sides of the second roller gap. The separator film is then peeled off and the composite double-sided dry electrode sheet is wound up.

[0070] Specifically, the current collector membrane is drawn from a non-powered unwinding shaft, allowing it to form a drooping arc under its own weight and enter the first roller gap. The non-powered unwinding shaft is a support shaft equipped only with rolling bearings and no drive device; the current collector membrane roll is mounted on this shaft and can rotate freely. After being drawn from the roll, the current collector membrane hangs naturally under gravity. Due to the membrane material's flexibility and its own weight, it forms an arc-shaped overhang during its descent. The curvature of this overhanging arc is determined by the membrane material's linear density, flexible modulus, and overhang height, typically with an arc length of 20-50 cm. This overhanging arc provides a natural buffer zone for the membrane material, absorbing vibrations and impacts during system operation.

[0071] Two dry electrode films are simultaneously unwound without power, allowing each film to enter the first roll gap by its own weight. Both films, suspended by their own weight, adhere to the current collector film, forming an initial composite. Specifically, both unwinding methods utilize a non-powered unwinding shaft structure. The two dry electrode films are drawn from opposite sides of the current collector film, forming a suspended arc similar to the current collector film under their own gravity. When the three films converge in the first roll gap, the gap width is adjusted to precisely accommodate the thickness of the three layers. At this point, the dry electrode films come into contact with the current collector film surface under slight pressure. Because the adhesive (such as PTFE fiber) on the surface of the dry electrode films has a certain degree of adhesion at room temperature, combined with slight contact pressure, this is sufficient to achieve initial bonding of the three layers, forming the initial composite.

[0072] A separator film is applied to both outer sides of the initial composite to obtain the composite to be heated. This composite then forms a drooping arc before entering the second roll gap. The separator film application process is achieved through the unwinding of the first and second separator films. The two separator films are introduced from both sides of the initial composite, and the guide rollers ensure that the separator films adhere tightly to the surface of the initial composite, forming a five-layer composite to be heated (separator film - dry electrode film - current collector film - dry electrode film - separator film). Due to the increased overall weight, the composite to be heated continues to form a more stable drooping arc under gravity, preparing it for entry into the second roll gap.

[0073] The composite material to be heated is hot-pressed and bonded through composite rollers on both sides of the second roller gap. Heating devices are installed inside the first and second composite rollers, with the operating temperature controlled between 80-200℃. This temperature range allows the PTFE binder in the dry electrode film to soften without completely melting. When the composite material to be heated passes through the second roller gap, it is subjected to linear pressure (typically 50-200 N / cm) applied by the composite rollers. Under the combined action of temperature and pressure, the softened binder penetrates and solidifies into the micro-uneven structure of the current collector film surface, forming a strong mechanical anchoring bond.

[0074] The separator film is peeled off and the laminated double-sided dry electrode sheet is wound up. After lamination, the separator film is separated from the double-sided dry electrode sheet at the exit of the second roll gap by a guiding device, and is then wound up and recovered by the first separator film and the second separator film, respectively. At this point, the double-sided dry electrode sheet has formed a stable composite structure, and is finally wound up by the dry electrode sheet winding device after being guided by the guide rollers.

[0075] The unpowered unwinding method of this application eliminates the active drive device, fundamentally avoiding tension fluctuations, synchronization errors and mechanical shocks that may be generated by the drive system. This ensures that all film materials are always in a stable low-tension state determined by their own weight, effectively preventing damage to the dry electrode film during unwinding and lamination, and ensuring the quality stability of the composite interface.

[0076] Furthermore, in one embodiment of the present invention, the dry electrode film roll lamination method further includes:

[0077] Please see Figure 2 During the bonding process between the dry electrode membrane and the current collector membrane, the quantity and / or quality information of solid particles that fall off from the dry electrode membrane due to bonding are acquired in real time to generate a first detection signal characterizing the quality of the bonding interface.

[0078] Specifically, the real-time acquisition of the quantity and / or quality information of solid particles detached from the self-drying electrode film due to bonding, in order to generate a first detection signal characterizing the bonding interface quality, includes:

[0079] Within the sampling time window of continuous production, the cumulative mass increment of detached particles is obtained, and combined with the vertical offset of the particle flight path, the inertial stability of the detached particles is determined, thus obtaining the first parameter characterizing the particle detachment characteristics.

[0080] Within the same time window, the concentration and continuous shift trend of the falling particles along the width of the membrane are analyzed to identify whether the particles are accumulated in the edge area of ​​the membrane for a long time, thus obtaining a second parameter characterizing the bonding consistency.

[0081] According to the front, middle and rear sections of the bonding process along the winding direction, the changing trend of the number of detached particles in each stage is statistically analyzed to determine the evolutionary stability of the bonding interface and obtain the third parameter.

[0082] The first parameter, the second parameter, and the third parameter are integrated to generate a first detection signal representing the quality status of the bonding interface.

[0083] The following is a detailed description of the steps involved in the above embodiments:

[0084] In the process of acquiring the cumulative mass increment of detached particles and determining inertial stability within a sampling time window during continuous production, the sampling time window refers to a preset data acquisition cycle of a fixed length, typically 2-3 seconds. This duration is sufficient to capture enough particle detachment events while ensuring real-time data processing. In some implementations, a high-precision weighing sensor can be installed at the bottom of the collection tray. At the beginning of each sampling time window, the collection tray is zeroed out, and the cumulative weight change of detached particles within that time window is continuously monitored to directly obtain the cumulative mass increment. The vertical offset of the particle flight path is detected using a high-speed CCD camera. The camera, in conjunction with an LED backlight, continuously captures the particle motion process at 500 frames per second. The actual vertical displacement distance is calculated by the pixel coordinate changes of the particle position between consecutive frames. When the deviation between the actual vertical displacement of a particle and the theoretical free-fall distance exceeds 8%, the particle is considered to have poor inertial stability. This threshold is determined based on measured data of normal airflow disturbances in the dry electrode film production environment. Inertial stability is characterized by the percentage of stable particles out of the total number of detached particles, and this is combined with the cumulative mass increment to generate the first parameter. This method can directly reflect the strength of material bonding during the dry electrode film pressing process. Films with good pressing quality have large particles that detach and move along stable trajectories.

[0085] The distribution analysis of detached particles can be achieved by arranging a pressure-sensitive membrane at the bottom of the collection tray. This membrane is divided into seven equally wide detection areas along the width of the membrane material, with one area at each end defined as the edge area and the five areas in the middle as the center area. Whenever a particle falls into the collection tray, the pressure sensor in the corresponding area generates an electrical signal, and a counter counts the number of particle falls in each area within the sampling time window. The concentration degree is quantified by calculating the variance of the number of particles in each area; a larger variance indicates a more uneven particle distribution. The identification of a continuous shift trend is achieved by linearly fitting the change in the proportion of particles in the edge area within five consecutive sampling time windows. When the slope of the fitted line is greater than 0.02 (i.e., the proportion of the edge area increases by more than 2% in each time window), a continuous shift towards the edge is identified. This shift usually indicates uneven tension or misalignment during the bonding process between the dry electrode membrane and the current collector membrane, making the membrane material in the edge area more prone to shearing and detachment. The second parameter, combining the values ​​of concentration degree and shift trend, can accurately assess the symmetry and consistency of the double-sided simultaneous bonding process.

[0086] The stability assessment of the bonding process evolution was achieved using a time-series segmented statistical method. The bonding process of each roll of dry electrode film was divided into three stages: the initial stage, the middle stage, and the final stage, each lasting 15 seconds. The total number of particles detached was accumulated in each stage. A normal bonding evolution process should show a decreasing trend: the initial stage produces more detachments due to initial positional adjustments; the middle stage gradually stabilizes and the number of detachments decreases; and the final stage maintains a stable low detachment level. By calculating the reduction ratio of detachments between adjacent stages, a reduction ratio of less than 20% between the initial and middle stages or less than 10% between the middle and final stages indicates instability in the bonding process. For example, in one test, 120 particles detached in the initial stage, 100 in the middle stage, and 95 in the final stage, with a reduction of only 16.7% between the initial and middle stages, indicating slow improvement in the bonding interface quality and potential issues such as insufficient stress release within the film material. The third parameter quantifies this evolution trend, providing a basis for identifying abnormal fluctuations in the bonding process.

[0087] The three parameters were integrated using a linear weighted summation method, with weights allocated as follows: first parameter 0.4, second parameter 0.35, and third parameter 0.25. The first parameter (inertial stability) reflects the quality of the dry electrode film pressing and the strength of the material bonding, which is a fundamental factor affecting the quality of the bonding interface. Poor quality of the film material itself directly leads to a large number of particles falling off and weak interface bonding; therefore, it is assigned the highest weight of 0.4. The second parameter (bonding consistency) reflects the symmetry and uniformity of the double-sided simultaneous bonding process. Inconsistent bonding can cause local stress concentration and interface defects, significantly affecting the final product quality; its weight is set at 0.35. The third parameter (evolutionary stability) mainly reflects the temporal trend of the bonding process. Although it has important reference value for quality evaluation, its impact is relatively smaller than the first two parameters; its weight is set at 0.25. The three normalized parameter values ​​are multiplied by their corresponding weights and then summed to obtain the first detection signal within the range of 0-1. The closer the value is to 1, the better the bonding interface quality. This weighting method, based on process mechanism and experimental verification, can accurately reflect the true contribution of each parameter to the bonding quality, providing a reliable quality evaluation basis for the precise adjustment of subsequent process parameters.

[0088] In one embodiment of the present invention, the step of acquiring the cumulative mass increment of detached particles within a sampling time window of continuous production, and combining this with the vertical offset of the particle flight path to determine the inertial stability of the detached particles, thereby obtaining a first parameter characterizing the particle detachment characteristics, includes:

[0089] The cumulative mass increment of the sampling time window is obtained by summing the individual particle masses of all detached particles detected within the sampling time window.

[0090] According to the preset single particle mass threshold, the detached particles are divided into heavy particle group and light particle group;

[0091] Based on the mass of a single particle in the heavy-mass particle group and the light-mass particle group respectively, the vertical offset of the corresponding particles is averaged by mass weight to obtain the mean offset of the heavy-mass particle group and the mean offset of the light-mass particle group.

[0092] The inertial stability index is determined by using the cumulative mass increment, the proportion of heavy particles, the average heavy mass offset, and the average light mass offset, and the inertial stability index is used as the first parameter.

[0093] The following is a detailed description of the steps involved in the above embodiments:

[0094] The process of summing the individual particle masses of all detached particles detected within the sampling time window is achieved through instantaneous weight detection using a weighing sensor at the bottom of the collection tray. When a particle detaches and impacts the surface of the collection tray, the sensor generates a corresponding electrical signal pulse, with the amplitude of each pulse directly corresponding to the mass value of a single particle. Within the sampling time window, the data processing system continuously records all detected pulse signals and accumulates the amplitudes of each pulse to obtain the cumulative mass increment for that time window. For example, if 15 particles are detected within a certain sampling time window, with masses of 2.3 mg, 1.8 mg, 3.1 mg, etc., the cumulative mass increment is 28.7 mg. This real-time accumulation method accurately reflects the total material loss of the dry electrode film during the bonding process, providing a direct quantitative indicator for evaluating the bonding strength of the film materials.

[0095] The process of grouping detached particles according to a preset single-particle mass threshold is determined based on the material characteristics of dry electrode film molding. The single-particle mass threshold is set at 2.5 mg, which is determined according to the typical size distribution of active material particles and binder fibers in the dry electrode film: particles with a mass greater than 2.5 mg are mainly active material aggregates or composite particles containing a large amount of binder, and are classified as heavy particles; particles with a mass less than or equal to 2.5 mg are mainly single active material particles or loose binder fragments, and are classified as light particles. The grouping process is automatically completed by the data processing unit. The system compares the mass of each detected particle with the threshold and marks it as the corresponding group. This grouping method can distinguish the particle types corresponding to different detachment mechanisms. The detachment of heavy particles often indicates internal structural damage to the membrane material, while the detachment of light particles mainly reflects the natural peeling of loose surface materials.

[0096] The process of calculating the mean offset of heavy and light mass particles using a weighted average method combines particle mass information and motion trajectory data. For each particle in the heavy mass particle group, its vertical offset is multiplied by its corresponding single particle mass. The sum of all products is divided by the total mass of the particles in the group to obtain the mean offset of the heavy mass. The mean offset of the light mass particle is obtained using the same calculation method. For example, if the masses of three particles in the heavy mass particle group are 3.1 mg, 2.8 mg, and 3.5 mg, and their corresponding vertical offsets are 8 mm, 12 mm, and 6 mm, then the mean offset of the heavy mass particle is (3.1 × 8 + 2.8 × 12 + 3.5 × 6) ÷ (3.1 + 2.8 + 3.5) = 8.7 mm. This weighted averaging method ensures that particles with larger masses contribute more to the average value, and can more accurately reflect the differences in motion characteristics of particle groups with different masses.

[0097] The determination of the inertial stability index comprehensively considers four parameters: cumulative mass increment, proportion of heavy particles, mean heavy mass offset, and mean light mass offset. The proportion of heavy particles is calculated by dividing the total mass of the heavy particle group by the cumulative mass increment; this ratio reflects the degree of structure of the detached particles. When the proportion of heavy particles exceeds 60% and the mean heavy mass offset is less than 10 mm, it indicates that the detached particles are mainly structured and move stably, and the inertial stability index is set at 0.8-1.0. When light particles dominate and the mean light mass offset is greater than 15 mm, it indicates that the detached particles are mainly loose and easily disturbed, and the inertial stability index is set at 0.3-0.5. In other cases, the index is set at 0.5-0.8. This index comprehensively reflects the quality of dry electrode film pressing and the material stability during the bonding process, providing important physical property basis for subsequent bonding interface quality assessment.

[0098] In one embodiment of the present invention, the step of analyzing the concentration and continuous offset trend of the landing points of detached particles along the width direction of the membrane material within the same time window, and identifying whether the particles are accumulated in the edge area of ​​the membrane material for a long time, to obtain a second parameter characterizing the adhesion consistency, includes:

[0099] Within the same sampling time window, the landing points of the detached particles are divided into equal-width sections according to the width of the membrane material. The number of particles in each section is counted and the proportion of particles in the edge area to the total number of particles in the whole membrane is calculated.

[0100] Within several adjacent sampling time windows, an autoregressive calculation is performed on the proportion of the edge region to obtain the edge bias persistence coefficient;

[0101] A fitting consistency index is generated based on the edge area ratio and the edge offset persistence coefficient, and the fitting consistency index is used as the second parameter.

[0102] The following is a detailed description of the steps involved in the above embodiments:

[0103] The process of dividing the landing points of detached particles into equal-width sections along the membrane width direction within the same sampling time window is achieved through a pressure-sensitive membrane arranged at the bottom of the collection tray. This pressure-sensitive membrane divides the membrane width into seven equal-width detection areas, each with a width of 1 / 7 of the dry electrode membrane width, approximately 150 mm. When a particle falls into the collection tray, the pressure-sensitive membrane in the corresponding area generates an electrical signal, and the data acquisition system records the number of particle falls in each area within the sampling time window. The edge areas are defined as one area at each end of the collection tray, namely areas 1 and 7, while the central areas are areas 2 to 6. The proportion of particles in the edge areas to the total number of particles is calculated by dividing the total number of particles in the edge areas by the total number of particles in all seven areas. For example, if 8 particles are detected in area 1 and 12 particles in area 7 within a certain sampling time window, and a total of 100 particles are detected in all areas, then the proportion in the edge areas is (8+12)÷100=20%. This method of region division can accurately identify asymmetric phenomena during the dry electrode film bonding process. When the proportion of the edge area exceeds 30%, it indicates that there is a significant problem of concentrated edge detachment.

[0104] The process of obtaining the edge bias persistence coefficient by performing autoregressive calculations on the edge region proportions within several adjacent sampling time windows employs time series analysis. Autoregression is a mathematical method that uses previous data to predict current data; in practice, edge region proportion data from five consecutive sampling time windows are selected as the input sequence. The edge bias persistence coefficient is obtained by calculating the correlation coefficient between the edge region proportions of consecutive time windows. When the edge region proportions of the previous time window and the edge region proportions of the subsequent time window show a positive correlation and the correlation coefficient is greater than 0.7, it indicates that the edge bias phenomenon has a persistent characteristic. For example, if the edge region proportions of five consecutive time windows are 18%, 22%, 25%, 28%, and 30%, showing an increasing trend and a correlation coefficient of 0.89, then the edge bias persistence coefficient is set to 0.89. This coefficient reflects the temporal stability of the edge concentration phenomenon; a higher persistence coefficient indicates a more severe and longer-lasting inconsistency problem.

[0105] The process of generating a bonding consistency index based on the edge area ratio and edge offset persistence coefficient comprehensively considers both spatial distribution and temporal evolution. The calculation logic for the bonding consistency index is as follows: when the edge area ratio is less than 25% and the edge offset persistence coefficient is less than 0.5, it indicates uniform particle distribution with no persistent offset trend, and the bonding consistency index is set at 0.8-1.0; when the edge area ratio is between 25% and 35% and the edge offset persistence coefficient is between 0.5 and 0.8, it indicates a slight edge concentration phenomenon, and the bonding consistency index is set at 0.5-0.8; when the edge area ratio exceeds 35% and the edge offset persistence coefficient exceeds 0.8, it indicates severe edge concentration and continuous deterioration, and the bonding consistency index is set at 0.2-0.5. This index, as a second parameter, accurately reflects the symmetry and uniformity issues in the double-sided simultaneous bonding process. Edge concentration is often caused by uneven tension, alignment deviation, or improper roller gap adjustment. By quantitatively assessing the severity and persistence of these problems, a precise decision-making basis is provided for subsequent process parameter adjustments.

[0106] In one embodiment of the present invention, the step of statistically analyzing the changing trend of the number of detached particles at each stage according to the front, middle, and rear sections of the bonding process along the rolling direction, and determining the evolutionary stability of the bonding interface to obtain a third parameter includes:

[0107] Within a continuous sampling time window, the sampling time window is divided into a front section, a middle section, and a rear section according to the direction of roll-in. The number of detached particles in each section is accumulated to obtain the number of particles in the front section, the number of particles in the middle section, and the number of particles in the rear section.

[0108] The front-to-middle section attenuation rate is calculated based on the number of particles in the front section and the number of particles in the middle section, and the middle-to-rear section attenuation rate is calculated based on the number of particles in the middle section and the number of particles in the rear section.

[0109] The attenuation rates of the front-middle section and the middle-rear section are weighted and combined to generate a bonding evolution stability index, which is then used as the third parameter.

[0110] The following is a detailed description of the steps involved in the above embodiments:

[0111] The process of dividing the continuous sampling time window into front, middle, and rear segments according to the winding direction is based on the continuous characteristics of dry electrode film roll-to-roll production. The winding direction refers to the direction in which the dry electrode film moves from the unwinding device to the winding device (in this application, the winding direction can be understood as the direction of the machine body from top to bottom). The continuous sampling time window is set to 45 seconds, which corresponds to approximately 15 meters of film material passing through the bonding area. The time window is divided into equal-length segments, with each segment (front, middle, and rear) occupying 15 seconds. Within each time segment, the data acquisition system continuously monitors the signal of the pressure-sensitive film at the bottom of the collection tray and counts the number of detached particles in real time. The number of particles in the front segment reflects the adjustment detachment in the initial bonding stage, the number of particles in the middle segment reflects the stability in the bonding transition stage, and the number of particles in the rear segment reflects the continuity of the bonding stability stage. For example, in a certain continuous test, 120 particles were detected in the front segment, 80 particles were detected in the middle segment, and 60 particles were detected in the rear segment, showing a decreasing trend. This time-series segmented statistics can identify the dynamic changes during the bonding process. Normal bonding evolution should be characterized by a gradual decrease and stabilization of the number of detached particles over time.

[0112] The calculation of the front-to-middle section attenuation rate and the middle-to-back section attenuation rate, based on the number of front and middle section particles and the number of middle and back section particles respectively, uses a percentage reduction calculation method. The front-to-middle section attenuation rate is calculated as (number of front section particles - number of middle section particles) ÷ number of front section particles × 100%, and the middle-to-back section attenuation rate is calculated as (number of middle section particles - number of back section particles) ÷ number of middle section particles × 100%. A higher attenuation rate indicates a more significant reduction in particle shedding and a more significant improvement in bonding quality. Taking the aforementioned example, the front-to-middle section attenuation rate is (120-80) ÷ 120 × 100% = 33.3%, and the middle-to-back section attenuation rate is (80-60) ÷ 80 × 100% = 25.0%. A front-to-middle section attenuation rate of less than 20% indicates poor initial bonding effect, while a middle-to-back section attenuation rate of less than 15% indicates a lack of continuous improvement in the bonding process. This phased decay rate calculation can accurately quantify the speed and extent of quality improvement during the bonding process, providing quantitative criteria for identifying bonding abnormalities.

[0113] The process of weighted merging of the pre-mid stage attenuation rate and the mid-to-rear stage attenuation rate to generate a bonding evolution stability index comprehensively considers the difference in importance between the two stages. The weight of the pre-mid stage attenuation rate is set to 0.6, and the weight of the mid-to-rear stage attenuation rate is set to 0.4. This weight allocation is determined based on the process characteristic that the transition from the pre-mid stage to the mid-mid stage has a more critical impact on bonding quality. The bonding evolution stability index is calculated by multiplying the pre-mid stage attenuation rate by 0.6 and the mid-to-rear stage attenuation rate by 0.4, with a value range of 0-100%. When the index value is greater than 30%, it indicates good bonding evolution stability; when the index value is between 20% and 30%, it indicates moderate evolution stability; and when the index value is less than 20%, it indicates poor evolution stability. Taking the aforementioned example, the bonding evolution stability index is 33.3% × 0.6 + 25.0% × 0.4 = 29.98%, which falls within the moderate range of evolution stability. This indicator, as the third parameter, can comprehensively reflect the temporal evolution characteristics of the dry electrode film bonding process and identify unstable factors in the bonding process. When the evolution stability is poor, it often indicates that the internal stress of the film material is not fully released or that the bonding conditions fluctuate.

[0114] Please see Figure 2 The first detection signal is compared with a preset threshold to obtain the interface quality deviation.

[0115] Specifically, comparing the first detection signal with a preset threshold to obtain the interface quality deviation includes:

[0116] Within each sampling time window, the first detection signal is normalized according to the winding speed to obtain a speed-normalized signal;

[0117] Based on the edge offset duration coefficient of the time window corresponding to the velocity normalization signal, the preset benchmark threshold is corrected to generate a dynamic threshold.

[0118] The speed-normalized signal is compared with the dynamic threshold to obtain the instantaneous deviation value;

[0119] Within a preset roll length section, calculate the section average deviation for continuous instantaneous deviation values;

[0120] The interface quality deviation is generated based on the instantaneous deviation value and the average deviation of the section.

[0121] The following is a detailed description of the steps involved in the above embodiments:

[0122] The process of normalizing the first detection signal according to the winding speed within each sampling time window to obtain a speed-normalized signal is achieved through real-time speed monitoring and numerical standardization. The winding speed is measured by an encoder installed on the dry electrode winding device. The encoder output pulse signal corresponds to the distance the film material moves. The data processing system calculates the real-time winding speed in meters per minute based on the number of pulses per unit time. Speed ​​normalization involves dividing the first detection signal value by the current winding speed and then multiplying it by a standard speed, which is set to 20 meters per minute. For example, if the first detection signal is 0.65 within a certain sampling time window and the real-time winding speed is 25 meters per minute, then the speed-normalized signal is 0.65 ÷ 25 × 20 = 0.52. This normalization process eliminates the influence of production speed variations on the signal value, ensuring consistent quality evaluation standards across different production speeds and avoiding misjudgments caused by speed fluctuations.

[0123] The process of generating a dynamic threshold by correcting a preset baseline threshold based on the edge offset persistence coefficient of the time window corresponding to the velocity normalized signal employs an adaptive threshold adjustment method. The preset baseline threshold is set to 0.75, a value determined based on the signal level under normal bonding conditions. The coefficient correction process is as follows: when the edge offset persistence coefficient is less than 0.3, the dynamic threshold equals the baseline threshold multiplied by 1.0, maintaining the original standard; when the edge offset persistence coefficient is between 0.3 and 0.7, the dynamic threshold equals the baseline threshold multiplied by 0.9, appropriately lowering the judgment standard; when the edge offset persistence coefficient is greater than 0.7, the dynamic threshold equals the baseline threshold multiplied by 0.8, significantly lowering the judgment standard. For example, if the edge offset persistence coefficient for a certain time window is 0.65, then the dynamic threshold is 0.75 × 0.9 = 0.675. This adaptive adjustment mechanism considers the impact of bonding consistency on quality judgment, lowering the threshold standard when edge offset is severe to avoid overly strict judgment leading to false alarms.

[0124] The process of obtaining the instantaneous deviation value by comparing the speed-normalized signal with a dynamic threshold is achieved through numerical difference calculation. The instantaneous deviation value equals the dynamic threshold minus the speed-normalized signal. A positive result indicates that the signal is below the threshold standard, indicating a quality deviation; a negative result or zero indicates that the signal meets or exceeds the threshold standard, indicating acceptable quality. For example, if the speed-normalized signal is 0.52 and the dynamic threshold is 0.675, then the instantaneous deviation value is 0.675 - 0.52 = 0.155. The magnitude of the instantaneous deviation value directly reflects the degree of difference between the bonding interface quality and the standard requirements within the current time window; a larger value indicates a more severe quality deviation. This real-time deviation calculation provides immediate quality feedback information for subsequent process parameter adjustments.

[0125] The process of calculating the segment average deviation for continuous instantaneous deviation values ​​within a preset roll length segment is based on a moving average algorithm. The preset roll length segment is set to 10 meters, corresponding to approximately 20 consecutive sampling time windows. The segment average deviation is calculated by taking the arithmetic mean of all instantaneous deviation values ​​within this 10-meter segment, only calculating positive deviations; negative and zero values ​​are not included in the averaging calculation. For example, if there are 15 positive instantaneous deviation values ​​within the 10-meter segment, such as 0.155, 0.120, and 0.098, the segment average deviation is the sum of all positive values ​​divided by the number of positive values. This segment averaging calculation can smooth out instantaneous fluctuations, reflect the overall quality level over a longer distance, and avoid the excessive influence of single-point anomalies on quality evaluation.

[0126] The process of generating the interface quality deviation based on the instantaneous deviation value and the average deviation of the section comprehensively considers both immediacy and trend. The interface quality deviation is calculated by weighted summation of the instantaneous deviation value and the average deviation of the section, with weights of 0.7 and 0.3, respectively. When the instantaneous deviation value is 0.155 and the average deviation of the section is 0.132, the interface quality deviation is 0.155 × 0.7 + 0.132 × 0.3 = 0.1485. This weighting allocation considers both the current quality status and the influence of historical trends, accurately reflecting the overall level of the bonding interface quality. The interface quality deviation provides a quantitative control basis for the precise adjustment of subsequent process parameters; when the deviation exceeds the set limit, corresponding adjustment actions are triggered.

[0127] In one embodiment of the present invention, the step of correcting a preset reference threshold based on the edge offset duration coefficient of the time window corresponding to the velocity normalization signal to generate a dynamic threshold includes:

[0128] The edge offset duration coefficient of the sampling time window corresponding to the velocity normalized signal is used as the first correction factor to make the first correction to the preset benchmark threshold.

[0129] The threshold after the first correction is corrected a second time based on the fitting evolution stability index of the time window corresponding to the edge bias duration coefficient.

[0130] Based on the temperature range of the current production environment, the temperature range coefficient is retrieved, and the threshold after the second correction is adjusted for temperature to obtain the dynamic threshold.

[0131] The following is a detailed description of the steps involved in the above embodiments:

[0132] The process of initially correcting the preset baseline threshold using the edge offset persistence coefficient as the first correction factor is implemented through a piecewise correction algorithm. The first correction factor directly adopts the edge offset persistence coefficient value corresponding to the sampling time window, which ranges from 0 to 1. The initial correction is performed according to the following rules: when the edge offset persistence coefficient is less than 0.3, the threshold after the initial correction is equal to the preset baseline threshold multiplied by 1.05, appropriately increasing the judgment standard; when the edge offset persistence coefficient is between 0.3 and 0.7, the threshold after the initial correction is equal to the preset baseline threshold multiplied by 1.0, maintaining the original standard; when the edge offset persistence coefficient is greater than 0.7, the threshold after the initial correction is equal to the preset baseline threshold multiplied by 0.85, significantly reducing the judgment standard. For example, if the preset baseline threshold is 0.75 and the edge offset persistence coefficient is 0.82, then the threshold after the initial correction is 0.75 × 0.85 = 0.6375. This correction mechanism reflects the impact of fit consistency on the quality judgment standard, reducing the threshold requirement when the edge offset phenomenon is severe, and avoiding overly strict judgment due to concentrated edge detachment.

[0133] The process of revising the threshold based on the bonding evolution stability index after the initial correction is based on adjusting the judgment criteria according to the temporal evolution characteristics. The bonding evolution stability index ranges from 0-100%. The second correction rule is as follows: when the bonding evolution stability index is greater than 30%, the threshold after the second correction is equal to the threshold after the initial correction multiplied by 1.0, maintaining the current standard; when the bonding evolution stability index is between 20% and 30%, the threshold after the second correction is equal to the threshold after the initial correction multiplied by 0.95, slightly lowering the standard; when the bonding evolution stability index is less than 20%, the threshold after the second correction is equal to the threshold after the initial correction multiplied by 0.9, further lowering the standard. For example, if the threshold after the initial correction is 0.6375 and the bonding evolution stability index is 18%, then the threshold after the second correction is 0.6375 × 0.9 = 0.57375. This correction takes into account the stability impact of the temporal evolution of the bonding process, appropriately relaxing the judgment conditions when the evolution is unstable, ensuring the adaptability of the control system under complex operating conditions.

[0134] The process of temperature correction based on the temperature range of the current production environment is achieved through environmental temperature monitoring and range coefficient lookup. The production environment temperature is monitored in real-time using digital thermometers installed near the equipment. The temperature range is divided into three zones: 15-20℃ is the low-temperature zone (temperature zone coefficient 1.08); 20-25℃ is the normal-temperature zone (temperature zone coefficient 1.0); and 25-30℃ is the high-temperature zone (temperature zone coefficient 0.92). The dynamic threshold is equal to the threshold after the second correction multiplied by the corresponding temperature zone coefficient. For example, if the current ambient temperature is 27℃, belonging to the high-temperature zone, and the threshold after the second correction is 0.57375, then the dynamic threshold is 0.57375 × 0.92 = 0.5279. The temperature correction mechanism considers the impact of ambient temperature on the characteristics of dry electrode film materials and particle shedding behavior. At high temperatures, the film material becomes more flexible and the shedding threshold decreases; at low temperatures, the film material becomes more brittle and the shedding threshold increases. Temperature correction ensures the rationality and consistency of quality judgment standards under different environmental conditions.

[0135] Please see Figure 2 Based on the interface quality deviation, at least one bonding process parameter is dynamically adjusted. The bonding process parameter includes at least one of the following: first roller gap width, bonding roller linear pressure, unwinding shaft damping torque, overhang arc length, and roll material linear speed, so as to maintain or restore the bonding interface quality to the target range.

[0136] Specifically, the step of dynamically adjusting at least one bonding process parameter based on the interface quality deviation, wherein the bonding process parameter includes at least one of the following: first roller gap width, bonding roller linear pressure, unwinding shaft damping torque, overhang arc length, and roll material linear speed, to maintain or restore the bonding interface quality to the target range, including:

[0137] The amplitude, direction, and duration of the interface quality deviation within the current sampling time window are classified, determined, and calculated to identify the main cause of the deviation.

[0138] Based on the main cause of the deviation, the bonding process parameters to be adjusted are selected. When the main cause of the deviation is edge shearing, the opposite side overhang arc length and unwinding shaft damping torque are selected. When the main cause of the deviation is center bulging, the first roller gap width and bonding roller line pressure are selected. When the main cause of the deviation is full-width pulverization, the roll material line speed is selected.

[0139] The selected bonding process parameters are adjusted according to the preset adjustment range;

[0140] During the subsequent verification sampling time window, monitor the interface quality deviation. If the deviation still exceeds the target range, repeat the process of determining the main cause, selecting parameters, and adjusting until the deviation returns to the target range.

[0141] The following is a detailed description of the steps involved in the above embodiments:

[0142] The process of determining the main cause of interface quality deviation by classifying its amplitude, determining its direction, and calculating its duration is implemented through a multidimensional analysis algorithm. Amplitude classification divides the interface quality deviation into three levels based on its numerical value: 0.05-0.15 for slight deviation, 0.15-0.25 for moderate deviation, and above 0.25 for severe deviation. Direction determination refers to analyzing the spatial distribution characteristics of the interface quality deviation. When the proportion of particles in the edge region is greater than 35% and the edge offset persistence coefficient is greater than 0.7, it is determined to be edge shearing; when the proportion of particles in the central region is greater than 70% and the particle size is concentrated in the 1-3 mg range, it is determined to be central bulging; when the particles are evenly distributed across the entire area and the cumulative mass increment continues to increase, it is determined to be full-area pulverization. Duration calculation is achieved by statistically counting the number of sampling time windows in which the same type of deviation occurs consecutively. A deviation pattern is confirmed as stable if it persists for more than three time windows. For example, in a certain test, the interface quality deviation is 0.18, the proportion of particles in the edge region is 42%, the edge offset persistence coefficient is 0.83, and it persists for four time windows, then the main cause of the deviation is determined to be edge shearing. This multidimensional analysis can accurately identify the characteristic patterns corresponding to different failure mechanisms, avoiding the errors of judgment based on a single indicator.

[0143] The process of selecting the bonding process parameters to be adjusted based on the primary cause of deviation is achieved through a process mechanism matching principle. When the primary cause of deviation is edge shearing, the opposite side overhang arc length and the unwinding shaft damping torque are selected as the adjustment targets. The opposite side overhang arc length refers to the overhang arc length of the dry electrode film on the other side opposite to where edge shearing occurs. The overhang arc length is changed by adjusting the height of the unwinding device on that side, and the unwinding shaft damping torque is controlled by adjusting the damping coefficient of the bearing damper. When the primary cause of deviation is center bulging, the first roller gap width and the bonding roller line pressure are selected. The first roller gap width is achieved by adjusting the horizontal distance between the two dry film unwinding devices through a servo motor-driven screw, and the bonding roller line pressure is controlled by a cylinder pressure adjustment system to control the unit width pressure acting on the film material. When the primary cause of deviation is full-width pulverization, the roll material linear speed is selected, i.e., the speed of the entire production line is controlled by adjusting the rotation speed of the dry electrode take-up device through a frequency converter. For example, after determining that the primary cause of deviation is center bulging, the system automatically selects the first roller gap width and the bonding roller line pressure as adjustment parameters. This targeted parameter selection is based on the physical mechanism of each failure mode, ensuring that the adjustment action directly targets the root cause of the problem.

[0144] The process of adjusting the selected bonding process parameters according to preset adjustment ranges is achieved through an automated control system. The preset adjustment range is determined based on the deviation level: 5% of the standard value for slight deviations, 10% for moderate deviations, and 15% for severe deviations. Specific adjustment actions are as follows: the length of the opposite overhang arc is adjusted by a lifting device, with adjustments of 2-5 cm each time; the unwinding shaft damping torque is changed by a damping adjuster, with an adjustment range of 0.1-0.5 N·m; the first roll gap width is controlled by a servo motor, with adjustments of 0.2-1.0 mm each time; the bonding roller pressure is adjusted by a cylinder pressure, with adjustments of 10-50 N / cm each time; and the roll material speed is adjusted by a frequency converter, with adjustments of 1-3 m / min each time. For example, for a moderate center bulge deviation, the system increases the first roll gap width by 0.5 mm and reduces the bonding roller pressure by 20 N / cm. This graded adjustment mechanism avoids process fluctuations that may be caused by over-adjustment, ensuring the accuracy and controllability of the adjustment actions.

[0145] The process of monitoring interface quality deviation and performing iterative adjustments within the verification sampling time window is achieved through closed-loop feedback control. The verification sampling time window is set as the next sampling cycle after the adjustment action is completed, continuously monitoring changes in interface quality deviation. The target range is set to an interface quality deviation of less than 0.10. When the verification result shows that the deviation still exceeds the target range, the system automatically repeats the entire process of deviation analysis, parameter selection, and adjustment execution. The iterative adjustment process is executed a maximum of 5 times. If the deviation still exceeds the standard after 5 adjustments, an alarm signal is issued to prompt manual intervention. For example, if the deviation decreases from 0.18 to 0.13 after the first adjustment but still exceeds the target range, the system performs a second adjustment to further reduce the deviation to 0.08 to meet the target requirement. This iterative optimization mechanism ensures the thoroughness and effectiveness of process parameter adjustment, realizing a fully automated control closed loop from deviation identification to complete correction.

[0146] It is easy to understand that the embodiments of this application construct a complete "real-time quality monitoring and dynamic adjustment" technical system, fundamentally solving the technical limitations of traditional dry electrode film composite processes that rely on post-process inspection. This technical solution, by capturing and analyzing naturally occurring particle shedding information during the process in real time, transforms phenomena originally considered byproducts into valuable quality evaluation signals, achieving immediate monitoring and accurate assessment of the composite interface quality. The system can accurately identify different types of quality problems and automatically match corresponding process adjustment strategies, forming a complete closed-loop control system from quality inspection and deviation analysis to parameter adjustment. Compared with traditional post-process inspection methods, this solution can identify and correct quality problems at the first moment they occur, avoiding the generation of unqualified products and significantly improving production efficiency and material utilization.

[0147] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A dry electrode film roll-pressing method, characterized by, include: The current collector membrane is drawn out from the unpowered unwinding shaft, allowing it to form a hanging arc under its own weight and enter the first roller gap; Two dry electrode films are simultaneously unwound without power. The two dry electrode films are located on opposite sides of the overhang arc formed by the current collector film. Each dry electrode film enters the first roller gap by its own weight, and the two dry electrode films are attached to the current collector film by their own weight in the overhang state, thus obtaining an initial composite. The length of each current collector film and the two dry electrode films when they hang naturally under their own weight ranges from 20 to 50 cm. The width of the first roller gap is equal to the sum of the thickness of the current collector film and the thickness of the two dry electrode films. An isolation film is wrapped around the two outer sides of the initial composite to obtain the composite to be heated, and the composite to be heated is made into a hanging arc before entering the second roller gap; The composite to be heated is hot-pressed and bonded by the composite rollers on both sides of the second roller gap; The double-sided dry electrode sheet is peeled off and then wound up after lamination.

2. The dry electrode film roll-pressing compounding method according to claim 1, characterized by, The dry electrode film roll forming method further includes: During the bonding process between the dry electrode membrane and the current collector membrane, the quantity and / or quality information of solid particles that detach from the dry electrode membrane due to bonding are acquired in real time to generate a first detection signal characterizing the quality of the bonding interface. The first detection signal is compared with a preset threshold to obtain the interface quality deviation. Based on the interface quality deviation, at least one bonding process parameter is dynamically adjusted. The bonding process parameter includes at least one of the following: first roller gap width, bonding roller linear pressure, unwinding shaft damping torque, overhang arc length, and roll material linear speed, so as to maintain or restore the bonding interface quality to the target range.

3. The dry electrode film roll-pressing compounding method according to claim 2, characterized by, The real-time acquisition of the quantity and / or quality information of solid particles detached from the self-drying electrode film due to bonding, in order to generate a first detection signal characterizing the bonding interface quality, includes: Within the sampling time window of continuous production, the cumulative mass increment of detached particles is obtained, and combined with the vertical offset of the particle flight path, the inertial stability of the detached particles is determined, thus obtaining the first parameter characterizing the particle detachment characteristics. Within the same time window, the concentration and continuous shift trend of the falling particles along the width of the membrane are analyzed to identify whether the particles are accumulated in the edge area of ​​the membrane for a long time, thus obtaining a second parameter characterizing the bonding consistency. According to the front, middle and rear sections of the bonding process along the winding direction, the changing trend of the number of detached particles in each stage is statistically analyzed to determine the evolutionary stability of the bonding interface and obtain the third parameter. The first parameter, the second parameter, and the third parameter are integrated to generate a first detection signal representing the quality status of the bonding interface.

4. The dry electrode film roll-pressing compounding method according to claim 3, characterized by, Within the sampling time window of continuous production, the cumulative mass increment of detached particles is obtained, and combined with the vertical offset of the particle flight path, the inertial stability of the detached particles is determined to obtain a first parameter characterizing the particle detachment characteristics, including: The cumulative mass increment of the sampling time window is obtained by summing the individual particle masses of all detached particles detected within the sampling time window. According to the preset single particle mass threshold, the detached particles are divided into heavy particle group and light particle group; Based on the mass of a single particle in the heavy-mass particle group and the light-mass particle group respectively, the vertical offset of the corresponding particles is averaged by mass weight to obtain the mean offset of the heavy-mass particle group and the mean offset of the light-mass particle group. The inertial stability index is determined by using the cumulative mass increment, the proportion of heavy particles, the average heavy mass offset, and the average light mass offset, and the inertial stability index is used as the first parameter.

5. The dry electrode film roll-pressing compounding method according to claim 3, characterized by, Within the same time window, the concentration and continuous shift trend of the detached particles along the width of the membrane are analyzed to identify whether the particles accumulate in the edge area of ​​the membrane for a long time, thus obtaining a second parameter characterizing the adhesion consistency, including: Within the same sampling time window, the landing points of the detached particles are divided into equal-width sections according to the width of the membrane material. The number of particles in each section is counted and the proportion of particles in the edge area to the total number of particles in the whole membrane is calculated. Within several adjacent sampling time windows, an autoregressive calculation is performed on the proportion of the edge region to obtain the edge bias persistence coefficient; A fitting consistency index is generated based on the edge area ratio and the edge offset persistence coefficient, and the fitting consistency index is used as the second parameter.

6. The dry electrode film roll forming method according to claim 3, characterized in that, The method involves statistically analyzing the variation trend of particle detachment at each stage of the bonding process along the winding direction (front, middle, and rear sections) to determine the evolutionary stability of the bonding interface and obtain a third parameter, including: Within a continuous sampling time window, the sampling time window is divided into a front section, a middle section, and a rear section according to the direction of roll-in. The number of detached particles in each section is accumulated to obtain the number of particles in the front section, the number of particles in the middle section, and the number of particles in the rear section. The front-to-middle section attenuation rate is calculated based on the number of particles in the front section and the number of particles in the middle section, and the middle-to-rear section attenuation rate is calculated based on the number of particles in the middle section and the number of particles in the rear section. The attenuation rates of the front-middle section and the middle-rear section are weighted and combined to generate a bonding evolution stability index, which is then used as the third parameter.

7. The dry electrode film roll forming method according to claim 2, characterized in that, The step of comparing the first detection signal with a preset threshold to obtain the interface quality deviation includes: Within each sampling time window, the first detection signal is normalized according to the winding speed to obtain a speed-normalized signal; Based on the edge offset duration coefficient of the time window corresponding to the velocity normalization signal, the preset benchmark threshold is corrected to generate a dynamic threshold. The speed-normalized signal is compared with the dynamic threshold to obtain the instantaneous deviation value; Within a preset roll length section, calculate the section average deviation for continuous instantaneous deviation values; The interface quality deviation is generated based on the instantaneous deviation value and the average deviation of the section.

8. The dry electrode film roll forming method according to claim 7, characterized in that, The step of correcting the preset benchmark threshold based on the edge offset duration coefficient of the time window corresponding to the velocity normalization signal to generate a dynamic threshold includes: The edge offset duration coefficient of the sampling time window corresponding to the velocity normalized signal is used as the first correction factor to make the first correction to the preset benchmark threshold. The threshold after the first correction is corrected a second time based on the fitting evolution stability index of the time window corresponding to the edge bias duration coefficient. Based on the temperature range of the current production environment, the temperature range coefficient is retrieved, and the threshold after the second correction is adjusted for temperature to obtain the dynamic threshold.

9. The dry electrode film roll forming method according to claim 2, characterized in that, The step of dynamically adjusting at least one bonding process parameter based on the interface quality deviation, wherein the bonding process parameter includes at least one of the following: first roller gap width, bonding roller linear pressure, unwinding shaft damping torque, overhang arc length, and roll material linear speed, to maintain or restore the bonding interface quality to the target range, including: The amplitude, direction, and duration of the interface quality deviation within the current sampling time window are classified, determined, and calculated to identify the main cause of the deviation. Based on the main cause of the deviation, the bonding process parameters to be adjusted are selected. When the main cause of the deviation is edge shearing, the opposite side overhang arc length and unwinding shaft damping torque are selected. When the main cause of the deviation is center bulging, the first roller gap width and bonding roller line pressure are selected. When the main cause of the deviation is full-width pulverization, the roll material line speed is selected. The selected bonding process parameters are adjusted according to the preset adjustment range; During the subsequent verification sampling time window, monitor the interface quality deviation. If the deviation still exceeds the target range, repeat the process of determining the main cause, selecting parameters, and adjusting until the deviation returns to the target range.

10. A dry electrode film rolling mill, characterized in that, The dry electrode film rolling equipment adopts the dry electrode film rolling composite method as described in any one of claims 1 to 9.

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