A method for detecting the adhesion strength of a lithium ion battery separator, related equipment

Abstract

The application provides a kind of lithium ion battery separator adhesion strength detection method, related equipment, method includes: providing the test sample after heat pressing pretreatment, test sample includes mutually bonded pole piece layer and separator layer;With vacuum suction fixed platform adsorption pole piece layer, to fix pole piece layer;With vacuum suction stretching component, adsorption separator layer the first edge region and the second edge region of the surface deviating from pole piece layer;Drive vacuum suction stretching component relative to vacuum suction fixed platform to move away, or drive the first vacuum suction module in vacuum suction stretching component relative motion towards second vacuum suction module, to simultaneously exert tensile force on the first edge region and the second edge region;Based on the tensile force data of vacuum suction stretching component and the displacement data of separator layer, determine the adhesion strength data of separator layer.The application can improve the stability of adhesion strength detection, so that the adhesion strength data obtained is more accurate.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, specifically to a method and related equipment for testing the adhesion strength of a lithium-ion battery separator. Background Technology

[0002] In the manufacturing process of lithium-ion batteries, the interfacial adhesion strength between the electrode and the separator is a key indicator determining the structural stability, cycle life, and safety of the cell. Precise quantitative testing of this interfacial adhesion strength has become an important step in battery research and development and quality control.

[0003] In related technologies, a single-sided peel test is often performed on the separator and electrode of the disassembled battery cell. However, this method has poor stability and is out of sync with the bending stress scenario when the battery cell is squeezed, resulting in a large error in the final adhesion strength data. Summary of the Invention

[0004] The embodiments of this application provide a method and related equipment for detecting the adhesion strength of a lithium-ion battery separator, which aims to make the obtained adhesion strength data more accurate.

[0005] In a first aspect, embodiments of this application provide a method for detecting the adhesion strength of a lithium-ion battery separator, the method comprising:

[0006] Provide a test sample after hot pressing pretreatment, the test sample comprising an electrode layer and a separator layer bonded together, the test sample being used in a lithium-ion battery;

[0007] The electrode layer is fixed by adsorbing it using a vacuum adsorption fixation platform;

[0008] Using a vacuum adsorption stretching assembly, the first edge region and the second edge region of the surface of the diaphragm layer facing away from the electrode layer are adsorbed. The first edge region and the second edge region are located at opposite ends of the surface and are symmetrically arranged with respect to the center point of the surface.

[0009] The vacuum adsorption stretching assembly is driven to move away from the vacuum adsorption fixing platform, or the first vacuum adsorption module in the vacuum adsorption stretching assembly is driven to move relative to the second vacuum adsorption module, so as to apply tension to the first edge region and the second edge region simultaneously. The first vacuum adsorption module is used to adsorb the first edge region, and the second vacuum adsorption module is used to adsorb the second edge region.

[0010] During the process of driving the vacuum adsorption stretching component to move away from each other or to move relative to each other, the tensile force data applied by the vacuum adsorption stretching component to the first edge region and the second edge region, as well as the displacement data of the membrane layer, are collected.

[0011] Based on the applied tensile force data and the displacement data, the adhesion strength data of the membrane layer is determined.

[0012] In the above embodiments, the electrode layer is fixed by adsorbing it using a vacuum adsorption fixing platform, and the first and second edge regions of the diaphragm layer are symmetrically set with respect to the center point of the surface by a vacuum adsorption stretching component. The component is driven to move and apply tension to both ends simultaneously. Combined with the tension and displacement data collected during the process, symmetrical force loading on both sides of the test sample is achieved, avoiding stress concentration deviation caused by unilateral peeling. This improves the stability of adhesion strength detection and makes the obtained adhesion strength data more accurate.

[0013] In one embodiment, driving the vacuum adsorption stretching assembly to move away from the vacuum adsorption fixing platform includes:

[0014] Obtain the preset tensile test speed and total tensile stroke for the test sample;

[0015] Based on the tensile test speed and the total tensile stroke, a target speed-time control curve is generated, which includes an acceleration segment, a constant speed segment and a deceleration segment connected in sequence.

[0016] According to the target speed-time control curve, the vacuum adsorption stretching assembly is driven to move away.

[0017] In the above embodiments, the vacuum adsorption stretching assembly is driven by generating a target speed-time control curve containing acceleration, constant speed, and deceleration segments based on the stretching test speed and total stretching stroke. This smooths out inertial fluctuations during the start-stop phase of the motion, ensuring stability far from the motion process, thereby preventing mechanical vibration from interfering with the acquisition of tensile force data.

[0018] In one embodiment, driving the vacuum adsorption stretching assembly to move away according to the target speed-time control curve includes:

[0019] The vacuum adsorption stretching assembly is driven to move away at a preset low pre-tension speed, and the current applied tension in the applied tension data is detected to be greater than or equal to a preset tension threshold.

[0020] If the current applied tension is greater than or equal to the tension threshold, the current moment is marked as the starting point of the tension, and the collected displacement data is reset to zero.

[0021] Based on the S-shaped speed planning algorithm, a smooth acceleration curve is generated from the low-speed pre-tension speed to the constant speed segment speed.

[0022] The vacuum adsorption stretching component is driven to move away according to the smooth acceleration curve, so that the moving away motion of the vacuum adsorption stretching component switches from the acceleration segment to the uniform speed segment.

[0023] In the above embodiments, by eliminating the initial slack at a low pre-tensioning speed and resetting the displacement data when the tension threshold is reached, and by using a smooth acceleration curve generated by the S-shaped velocity planning algorithm for transition, the rigid start-up impact is eliminated, ensuring the accuracy of effective stroke measurement and the continuity of applied tension data.

[0024] In one embodiment, before driving the vacuum adsorption stretching assembly to perform a moving-away motion, the method further includes:

[0025] Obtain the current angle between the stretching axis direction of the vacuum adsorption stretching assembly and the normal direction of the adsorption surface of the vacuum adsorption fixing platform;

[0026] Determine the angular deviation value between the current included angle and the preset vertical stretching direction;

[0027] Adjust the direction of the stretching axis according to the angle deviation value so that the direction of the stretching axis coincides with the normal direction of the adsorption surface;

[0028] The vacuum adsorption stretching assembly is set to move away from the direction of the adjusted stretching axis.

[0029] In the above embodiments, by adjusting the direction of the stretching axis according to a determined angular deviation value so that it coincides with the normal direction of the adsorption surface, and setting the motion path accordingly, the interference of shear force generated by tilted stretching is eliminated, ensuring that the applied tension acts on the normal direction of the test sample, thereby ensuring the physical authenticity of the adhesion strength data.

[0030] In one embodiment, before driving the vacuum adsorption stretching assembly to move away from the vacuum adsorption fixing platform, or driving the first vacuum adsorption module in the vacuum adsorption stretching assembly to move relative to the second vacuum adsorption module, the method further includes:

[0031] Obtain the target operating temperature of the lithium-ion battery;

[0032] The temperature control module, located within the vacuum adsorption fixation platform, heats the test sample.

[0033] Monitor the real-time temperature of the test sample;

[0034] The real-time temperature is determined to be greater than or equal to the target operating temperature.

[0035] In the above embodiments, by controlling the temperature control module set in the vacuum adsorption fixation platform to heat the test sample and monitor the real-time temperature until it reaches the target working temperature, a specific thermal working environment is simulated, thereby realizing the differentiated evaluation of the interfacial bonding performance between the electrode layer and the separator layer under different temperature conditions.

[0036] In one embodiment, obtaining the target operating temperature of the lithium-ion battery includes:

[0037] Obtain the preset design parameters and preset operating condition parameters of the lithium-ion battery. The preset design parameters include thermal property data of positive and negative electrode materials and cell structure size data. The preset operating condition parameters include charge and discharge rate data.

[0038] Using a battery electrochemical-thermal coupling simulation model, simulation processing is performed based on the preset design parameters and the preset operating condition parameters to obtain the predicted temperature change data of the test sample;

[0039] The highest temperature value is determined from the predicted temperature change data and used as the target operating temperature.

[0040] In the above embodiments, the predicted temperature change data is obtained by using the battery electrochemical-thermal coupling simulation model based on preset design parameters and preset operating condition parameters, and the highest temperature value determined from it is used as the target operating temperature. This ensures that the test thermal environment matches the actual operating limit conditions, thereby improving the guiding value of the test results for battery application safety.

[0041] In one embodiment, determining the adhesion strength data of the membrane layer based on the applied tensile force data and the displacement data includes:

[0042] The effective peel width of the diaphragm layer is determined based on the physical width dimensions of the first edge region and the second edge region.

[0043] Generate a tension-displacement curve showing the change of the applied tension data as a function of the displacement data;

[0044] Based on the tension-displacement curve, the effective peeling stroke of the diaphragm layer is determined;

[0045] The effective peeling area is the product of the effective peeling stroke and the effective peeling width.

[0046] The integral area of ​​the tension-displacement curve within the effective peeling stroke is determined to obtain the peeling work data;

[0047] The adhesion strength data is determined based on the ratio of the peeling work data to the effective peeling area.

[0048] In the above embodiments, by determining the integral area of ​​the tension-displacement curve within the effective peeling stroke to obtain peeling work data, and calculating its ratio with the effective peeling area, the dynamically changing force response is transformed into a normalized index that can characterize the interface energy dissipation characteristics, thereby more comprehensively reflecting the interfacial bonding ability of the membrane layer.

[0049] Secondly, embodiments of this application provide an adhesion strength detection system for lithium-ion battery separators, the lithium-ion battery separator adhesion strength detection system being used to perform the adhesion strength detection method for lithium-ion battery separators as described in any of the preceding claims.

[0050] Thirdly, embodiments of this application provide an electronic device, the electronic device including a memory, a processor and a computer program stored in the memory, the processor executing the computer program to implement the adhesion strength detection method for lithium-ion battery separators as described in any of the preceding claims.

[0051] Fourthly, embodiments of this application provide a computer-readable storage medium storing a computer program configured to be executed by a processor to implement the adhesion strength detection method for lithium-ion battery separators as described in any of the preceding claims. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a schematic flowchart of an embodiment of the adhesion strength detection method for lithium-ion battery separators provided in this application;

[0054] Figure 2 This is a schematic diagram of a drive vacuum adsorption stretching assembly moving away from the vacuum adsorption fixing platform in an embodiment of this application;

[0055] Figure 3This is a schematic diagram of a drive vacuum adsorption stretching assembly in an embodiment of this application to move relative to a first vacuum adsorption module toward a second vacuum adsorption module.

[0056] Figure 4 This is another schematic diagram illustrating the relative movement of the first vacuum adsorption module toward the second vacuum adsorption module in the driving vacuum adsorption stretching assembly in an embodiment of this application.

[0057] Figure 5 This is a schematic diagram of an embodiment of the electronic device provided in this application. Detailed Implementation

[0058] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In addition, in the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0059] In a first aspect, embodiments of this application provide a method for detecting the adhesion strength of a lithium-ion battery separator, wherein the executing entity is a lithium-ion battery separator adhesion strength detection system (hereinafter referred to as the "system").

[0060] Specifically, refer to Figure 1 A method for testing the adhesion strength of lithium-ion battery separators may include:

[0061] S101. Provide a test sample after hot pressing pretreatment. The test sample includes an electrode layer and a separator layer bonded together. The test sample is used in lithium-ion batteries.

[0062] In this embodiment, the test sample refers to a layered composite structural unit used for physical performance testing, including mutually bonded electrode layers and separator layers. This test sample is a component simulating the internal structure of a lithium-ion battery cell, or a sample directly cut from a finished or semi-finished battery cell.

[0063] The electrode layer refers to the aluminum foil coated with the positive electrode active material or the copper foil coated with the negative electrode active material. The separator layer refers to the porous polymer film used to prevent physical contact between the positive and negative electrodes while allowing lithium ions to pass through, such as polyethylene (PE) or polypropylene (PP) film.

[0064] Hot-pressing pretreatment refers to the process of pressing the electrode layer and the separator layer together under preset temperature, pressure, and time conditions. Through hot-pressing pretreatment, the coating layer on the surface of the separator layer (such as polyvinylidene fluoride (PVDF) or ceramic coating) softens or melts, thereby forming a physical bond or chemical bond with the electrode layer.

[0065] In some embodiments of this application, the specific implementation of providing a test sample after hot-pressing pretreatment is as follows: Single-layer electrode layers cut to preset length and width dimensions are aligned and stacked with single-layer separator layers; the stacked components are placed in a flatbed hot press, with the hot-pressing temperature set to 60°C to 100°C, the hot-pressing pressure to 0.5 MPa to 5 MPa, and the holding time to 30 seconds to 180 seconds; after hot-pressing, the sample is cooled to room temperature to obtain a test sample in which the electrode layer and separator layer are tightly bonded. This step aims to ensure that the test sample has an interface bonding state consistent with the actual battery manufacturing process, thereby ensuring the accuracy of subsequent adhesion strength test data.

[0066] S102. The electrode layer is adsorbed and fixed using a vacuum adsorption platform.

[0067] In this embodiment, the vacuum adsorption fixing platform refers to a clamping device that has the function of generating vacuum negative pressure and smoothing the adsorption surface. The vacuum adsorption fixing platform typically includes a porous metal plate or an adsorption panel with multiple microgrooves, and is connected to a vacuum pump through an air passage. The adsorption electrode layer refers to the layer of electrodes that is tightly pressed onto the fixing platform by utilizing the pressure difference between atmospheric pressure and the negative pressure inside the vacuum adsorption fixing platform.

[0068] In some embodiments of this application, the specific implementation of using a vacuum adsorption fixing platform to adsorb the electrode layer is as follows: the electrode layer of the test sample is placed face down in the center of the adsorption area of ​​the vacuum adsorption fixing platform; the vacuum source is activated, causing the adsorption holes on the surface of the vacuum adsorption fixing platform to generate suction. The system can be configured with a negative pressure monitoring sensor. When the detected negative pressure value reaches a preset adsorption threshold (e.g., -80 kPa), it is determined that the electrode layer is in a completely fixed state, and this negative pressure state is maintained until the end of the test. Compared with using mechanical clamps, vacuum adsorption fixing can avoid mechanical damage to the edges of the electrode layer and ensure that the electrode layer is subjected to uniform force on the entire plane, preventing the electrode layer from warping or sliding during subsequent stretching.

[0069] S103. Using a vacuum adsorption stretching assembly, the first edge region and the second edge region of the surface of the separator layer away from the electrode layer are adsorbed. The first edge region and the second edge region are located at opposite ends of the surface and are symmetrically arranged with respect to the center point of the surface.

[0070] In this embodiment, the vacuum adsorption stretching assembly refers to an actuator capable of moving along a specific trajectory and possessing vacuum adsorption functionality. This assembly typically includes a precision linear module and a vacuum adsorption module mounted at the end of the module. The first edge region and the second edge region refer to non-functional areas or areas specifically reserved for test clamping at both ends of the upper surface of the separator layer along its length. Symmetrical arrangement means that these two regions are centrally or axially symmetrical with respect to the center point of the surface of the separator layer away from the electrode layer.

[0071] In some embodiments of this application, the specific implementation of using the vacuum adsorption stretching component to adsorb the first edge region and the second edge region is as follows: controlling the vacuum adsorption stretching component to descend to the contact position; using the first vacuum adsorption module to adsorb the first edge region, and using the second vacuum adsorption module to adsorb the second edge region. To address the problem of insufficient adsorption force due to the high permeability of the separator layer, the system can employ a high-flow-rate vacuum generator and set a flexible sealing ring (such as silicone material) on the contact surface between the vacuum adsorption module and the separator layer to form an effective sealed cavity, thereby establishing an adsorption force sufficient to overcome interfacial adhesion on the porous separator layer surface. By symmetrically adsorbing and simultaneously stretching both ends, the separator layer can form an arch-like stress structure in the initial stage of peeling. This stress method can simulate the interlayer normal tension experienced by the electrode assembly during the battery's expansion during charging and discharging, avoiding the shear stress concentration problem caused by unilateral peeling.

[0072] S104. Drive the vacuum adsorption stretching assembly to move away from the vacuum adsorption fixed platform, or drive the first vacuum adsorption module in the vacuum adsorption stretching assembly to move relative to the second vacuum adsorption module, so as to apply tension to the first edge region and the second edge region simultaneously. The first vacuum adsorption module is used to adsorb the first edge region, and the second vacuum adsorption module is used to adsorb the second edge region.

[0073] In the embodiments of this application, reference is made to Figure 2 "Motion away from the platform" refers to the displacement of the vacuum adsorption stretching assembly in a direction away from the fixed vacuum adsorption platform. (Refer to...) Figure 3 and Figure 4 Relative motion refers to the displacement movement of at least one independent module in the vacuum adsorption stretching assembly, such as the first vacuum adsorption module, towards the second vacuum adsorption module along a direction parallel to the surface of the vacuum adsorption fixing platform. Figure 3 In this configuration, the first vacuum adsorption module is positioned above the second vacuum adsorption module and moves downwards. Figure 4 In this configuration, the first vacuum adsorption module is located below the second vacuum adsorption module and moves upwards. Simultaneous application of tension means that the first edge region and the second edge region are subjected to traction at the same time, causing the separator layer to be at least partially peeled off from the electrode layer surface.

[0074] In some embodiments of this application, the specific implementation of driving the vacuum adsorption stretching assembly to move away from the platform is as follows: A servo motor or linear motor is controlled to drive the vacuum adsorption stretching assembly to move at a preset constant speed or variable speed curve along a direction away from the vacuum adsorption fixed platform. As the vacuum adsorption stretching assembly is lifted, the diaphragm layer is subjected to a tensile force in the direction away from the vacuum adsorption fixed platform, and this tensile force is transmitted to the bonding interface between the diaphragm layer and the electrode layer. When the tensile force is greater than the interfacial adhesion force, the diaphragm layer begins to gradually separate from the electrode layer from the edge towards the center. This step eliminates the need to use double-sided adhesive to bond the diaphragm, thus eliminating the interference of adhesive residue or the elastic modulus of the adhesive tape itself on the test results. The relative movement of the first vacuum adsorption module towards the second vacuum adsorption module in the vacuum adsorption stretching assembly can also be achieved based on the drive of a servo motor or linear motor, which will not be elaborated here.

[0075] S105. During the process of driving the vacuum adsorption stretching component to move away from each other or to move relative to each other, the data of the tension applied by the vacuum adsorption stretching component to the first edge region and the second edge region, as well as the displacement data of the diaphragm layer are collected.

[0076] In this embodiment, the applied tension data refers to the force signal detected in real time by the sensor during the peeling process. The displacement data refers to the distance moved by the vacuum adsorption stretching component relative to the initial adsorption position when adsorbing the membrane layer, or the distance moved by the first vacuum adsorption module relative to the initial adsorption position when adsorbing the membrane layer.

[0077] In some embodiments of this application, the specific implementation of acquiring applied tension data and displacement data is as follows: a high-precision force sensor connected in series in the transmission chain of the vacuum adsorption stretching component is used to record the change in tension value in real time at a preset sampling frequency; simultaneously, a grating ruler or servo encoder is used to record the corresponding displacement along the direction away from the vacuum adsorption fixed platform in real time. The data acquisition card performs time synchronization matching between the applied tension data and displacement data to form a one-to-one corresponding data pair. The system can monitor the fluctuation of the force value in real time. When it detects that the applied tension data drops sharply after reaching its peak and approaches zero, it determines that the diaphragm layer has been completely peeled off, and then stops acquiring data.

[0078] S106. Based on the applied tension data and displacement data, determine the adhesion strength data of the membrane layer.

[0079] In the embodiments of this application, adhesion strength data refers to a quantitative indicator that characterizes the tightness of the bonding between the diaphragm layer and the electrode layer, and may include average peel force, peak peel force, or peel strength per unit width, etc.

[0080] As can be seen, the embodiments of this application utilize a vacuum adsorption fixing platform to adsorb and fix the electrode layer, and utilize a vacuum adsorption stretching component to adsorb the first edge region and the second edge region symmetrically set with respect to the center point of the diaphragm layer relative to the surface. The component is driven to move and apply tension to both ends simultaneously. Combined with the tension data and displacement data collected during the process, symmetrical force loading on both sides of the test sample is achieved, avoiding stress concentration deviation caused by unilateral peeling, thereby improving the stability of adhesion strength detection and making the obtained adhesion strength data more accurate.

[0081] After reliably fixing and bilaterally symmetrically adsorbing the test sample, precisely controlling the motion variables during the stretching process becomes crucial to ensuring high accuracy of the test data. If the driving method is too coarse, it can easily introduce unexpected inertial force interference at the moment of peeling. Therefore, some embodiments of this application refine the step of "driving the vacuum adsorption stretching assembly to move away from the platform." Specifically, driving the vacuum adsorption stretching assembly to move away from the vacuum adsorption fixing platform includes:

[0082] S201. Obtain the preset tensile test speed and total tensile stroke for the test sample;

[0083] In this embodiment, the tensile test speed refers to the target movement rate of the vacuum adsorption tensile component in a stable motion state during adhesion strength testing, typically expressed in millimeters per minute (mm / min). This speed parameter directly affects the peel rheological behavior of the adhesive interface and needs to be set according to relevant testing standards. The total tensile stroke refers to the maximum displacement of the vacuum adsorption tensile component from the starting position to the stopping position. This value is typically set to be greater than the theoretical length required for complete peeling of the diaphragm layer to ensure that the separation of the entire interface is completed before the stroke ends.

[0084] S202. Based on the tensile test speed and total tensile stroke, generate a target speed-time control curve, which includes an acceleration segment, a constant speed segment, and a deceleration segment connected in sequence.

[0085] In this embodiment, the target speed-time control curve refers to a mathematical function describing the instantaneous speed of the vacuum adsorption stretching assembly as a function of time. The acceleration segment refers to the range where the speed gradually increases from zero to the stretching test speed; the constant speed segment refers to the range where the speed remains constant at the stretching test speed; and the deceleration segment refers to the range where the speed gradually decreases from the stretching test speed to zero. This curve is designed to eliminate the interference of inertial forces on the readings of the mechanical sensors at the moment of start and stop of motion.

[0086] S203. Drive the vacuum adsorption stretching component to move away according to the target speed-time control curve.

[0087] In this embodiment, the rotation of the motor associated with the vacuum adsorption stretching component can be controlled according to the target speed-time control curve, thereby driving the vacuum adsorption stretching component to move along a predetermined trajectory. Furthermore, during the process of driving the vacuum adsorption stretching component to move away, the system can use an encoder to provide real-time feedback on the actual speed of the vacuum adsorption stretching component, and correct the speed deviation using a proportional-integral-derivative (PID) algorithm to ensure that the vacuum adsorption stretching component starts according to the planned acceleration phase and remains stable at a constant speed when entering the peeling test zone.

[0088] As can be seen, the embodiments of this application drive the vacuum adsorption stretching component by generating a target speed-time control curve containing acceleration, constant speed and deceleration segments based on the stretching test speed and total stretching stroke. This suppresses inertial fluctuations during the start-stop phase of the motion and ensures the stability of the motion process, thereby preventing mechanical vibration from interfering with the acquisition of tensile force data.

[0089] After constructing a macroscopic motion strategy including acceleration and deceleration control, considering the soft, thin, and easily relaxed physical properties of the diaphragm material, if stretching is initiated directly according to the target speed-time control curve, the initial relaxation may cause the displacement data to be out of sync with the actual stress state. To address this, some embodiments of this application introduce microscopic pre-tension monitoring and an S-shaped smooth transition algorithm. Specifically, according to the target speed-time control curve, the vacuum adsorption stretching component is driven to move away, including:

[0090] S301, Drive the vacuum adsorption stretching assembly to move away at a preset low-speed pre-tensioning speed, and detect whether the current applied tension in the applied tension data is greater than or equal to the preset tension threshold.

[0091] In this embodiment, the low-speed pre-tensioning speed refers to a movement rate lower than the tensile test speed during the formal test, for example, set to 1 mm / min to 5 mm / min. This speed is used to slowly eliminate any looseness, wrinkles, or minor bends in the diaphragm layer before the test begins. The tension threshold refers to a preset small force value (e.g., 0.01 N (Newtons) to 0.05 N), which indicates that the diaphragm layer has transitioned from a loose state to a taut state without substantial interfacial peeling or material deformation.

[0092] S302. If the applied tension is greater than or equal to the tension threshold, mark the current moment as the starting point of the tension and reset the collected displacement data to zero.

[0093] In this embodiment, the stretching start point refers to the zero point in time during the formal testing process, at which point the diaphragm layer is in a critical state of just being stretched. Zeroing the displacement data means defining the current position as the logical zero point of the displacement coordinate system.

[0094] In some embodiments of this application, the specific implementation of resetting the collected displacement data to zero is as follows: Upon confirming that the applied tension is greater than or equal to the tension threshold, the system immediately triggers an interrupt signal and records the current encoder count value as the reference offset, i.e., the new zero point. All subsequent collected displacement data are calculated based on this new zero point. If this step is not performed, the test data will contain an invalid empty stroke, resulting in a large error in the calculated adhesion strength.

[0095] S303. Based on the S-shaped speed planning algorithm, a smooth acceleration curve is generated from the low-speed pre-tension speed to the constant speed segment.

[0096] In this embodiment, the S-shaped velocity planning algorithm refers to a motion control algorithm that limits the rate of change of acceleration. The velocity curve generated by this algorithm is S-shaped, and its acceleration curve is trapezoidal or sinusoidal. A smooth acceleration curve refers to a motion trajectory where the velocity is not only continuous, but also its first derivative (i.e., acceleration) and second derivative (i.e., jerk) change continuously.

[0097] In some embodiments of this application, the specific implementation of generating a smooth acceleration curve is as follows: the system calculates the acceleration time, uniform acceleration time, and deceleration time required to increase from the current low-speed pre-tensioning speed to the target tensile test speed based on preset maximum acceleration and maximum jerk parameters. The target speed value corresponding to each control cycle is calculated using a fifth-order polynomial or a seven-segment S-curve formula for interpolation. Compared to trapezoidal speed planning, S-curve speed planning can avoid the flexible impact caused by sudden speed changes, preventing the thin diaphragm material from unexpectedly breaking due to excessive inertial force during acceleration.

[0098] S304. Drive the vacuum adsorption stretching component to move away according to a smooth acceleration curve, so that the moving away motion of the vacuum adsorption stretching component switches from the acceleration segment to the uniform speed segment.

[0099] In this embodiment, the motor outputs corresponding torque according to the smooth acceleration curve data, driving the vacuum adsorption stretching component to move away. Once the movement speed of the vacuum adsorption stretching component reaches the preset stretching test speed, it can maintain constant speed operation, thereby completing the switch from the start-up acceleration phase to the stable test phase.

[0100] As can be seen, the embodiments of this application eliminate the initial slack by using a low pre-tensioning speed and resetting the displacement data when the tension threshold is reached. Combined with the smooth acceleration curve generated by the S-shaped speed planning algorithm for transition, the rigid start-up impact is eliminated, ensuring the accuracy of effective stroke measurement and the accuracy of applied tension data.

[0101] After solving the speed control problem during the stretching process, attention can also be paid to the uniformity of the tensile force applied to the first and second edge regions by the vacuum adsorption stretching assembly during its remote movement. Since the vacuum adsorption stretching assembly may experience slight mechanical misalignment during long-term operation, if the stretching axis does not coincide with the normal of the fixed platform, a shear force will be generated, causing systematic errors in the adhesion strength detection results. To address this, some embodiments of this application provide an alignment compensation scheme. Specifically, before driving the vacuum adsorption stretching assembly to move remotely, the following steps are also included:

[0102] S401. Obtain the current angle between the stretching axis direction of the vacuum adsorption stretching assembly and the normal direction of the adsorption surface of the vacuum adsorption fixing platform.

[0103] In this embodiment, the stretching axis direction refers to the geometric center line or force direction vector of the vacuum adsorption stretching assembly during its outward movement. The adsorption surface normal direction refers to the vector direction perpendicular to the adsorption plane of the vacuum adsorption fixing platform. The current angle refers to the geometric angle between the above two vectors in the spatial coordinate system. Ideally, the peel test requires this angle to be 0 degrees, i.e., perfectly vertically aligned.

[0104] In some embodiments of this application, the specific implementation of obtaining the current included angle is as follows: using a laser displacement sensor or a dual-axis tilt sensor installed on the side of the vacuum adsorption stretching assembly, the tilt of the stretching axis direction relative to the vertical line of gravity is scanned and calculated; simultaneously, the levelness of the vacuum adsorption fixing platform is calibrated using a level or a coordinate measuring machine. Alternatively, a machine vision system can be used to capture the relative positional relationship between the calibration mark of the vacuum adsorption stretching assembly and the reference plane of the fixing platform using a side camera, and the angular deviation between the two is calculated using an image processing algorithm, which is then used as the current included angle.

[0105] S402. Determine the angular deviation between the current included angle and the preset vertical stretching direction;

[0106] In this embodiment, the vertical stretching direction refers to the ideal test path direction that is completely parallel to the normal direction of the adsorption surface (with an included angle of 0 degrees). The angle deviation value refers to the difference between the current included angle and the ideal value of 0 degrees.

[0107] Furthermore, in the step of determining the angle deviation value, the system can calculate the deviation components in both the pitch and roll dimensions separately, and use them as the angle deviation value. For example, the system calculates that there is an angle deviation of +0.5 degrees in the X-axis direction and -0.2 degrees in the Y-axis direction.

[0108] S403. Adjust the direction of the stretching axis according to the angle deviation value so that the direction of the stretching axis coincides with the normal direction of the adsorption surface;

[0109] In this embodiment, adjusting the direction of the stretching axis refers to changing the spatial orientation of the vacuum adsorption stretching assembly, the actuator, through a mechanical adjustment mechanism. Coincidence means that the angle between the adjusted stretching axis direction and the normal direction of the adsorption surface is less than the minimum allowable error range of the system (e.g., 0.01 degrees), which can be considered parallel in engineering.

[0110] In some embodiments of this application, the specific implementation of adjusting the direction of the stretching axis is as follows: controlling a multi-degree-of-freedom precision adjustment platform connected to the vacuum adsorption stretching component, such as a six-axis parallel robot platform. Based on the calculated angle deviation value, the system generates a reverse compensation command, driving the motor of the adjustment platform to rotate a specific angle, causing the vacuum adsorption stretching component to tilt and deflect until the current included angle returns to zero.

[0111] S404. According to the adjusted stretching axis direction, set the vacuum adsorption stretching component to move away from the motion path.

[0112] In this embodiment, the motion path refers to the displacement trajectory of the vacuum adsorption stretching component in three-dimensional space. Specifically, the original motion path of the vacuum adsorption stretching component when moving away can be corrected according to the adjusted stretching axis direction to ensure that the stretching force is fully applied in the direction perpendicular to the bonding interface, thus avoiding errors in the adhesion strength detection results caused by the shear force generated by tilted stretching.

[0113] As can be seen, the embodiments of this application adjust the direction of the stretching axis according to a determined angle deviation value so that it coincides with the normal direction of the adsorption surface, and set the motion path accordingly. This eliminates the interference of shear force generated by tilted stretching, ensures that the applied tension acts on the normal direction of the test sample, and thus guarantees the accuracy of the adhesion strength data.

[0114] After ensuring the smoothness of mechanical motion and the rationality of the motion path, the thermal boundary conditions of the test environment are equally important. Given that lithium-ion batteries often operate under different temperature conditions, and the physical properties of the adhesive layer are highly sensitive to temperature, this application also introduces a temperature control mechanism. Specifically, before driving the vacuum adsorption stretching assembly to move away from the vacuum adsorption fixed platform, or before driving the first vacuum adsorption module in the vacuum adsorption stretching assembly to move relative to the second vacuum adsorption module, the following steps are also included:

[0115] S501, Obtain the target operating temperature of the lithium-ion battery;

[0116] In the embodiments of this application, the target operating temperature refers to the expected operating temperature of the lithium-ion battery under specific application scenarios, or an extreme temperature point set for environmental adaptability testing. The binder inside the lithium-ion battery (such as polyvinylidene fluoride) is thermosensitive, and its mechanical properties change with temperature. Therefore, testing at a specific temperature is very important for evaluating battery safety.

[0117] S502, The temperature control module, located within the vacuum adsorption fixation platform, heats the test sample;

[0118] In this embodiment, the temperature control module refers to a temperature regulation device integrated inside the vacuum adsorption fixation platform, which may include, for example, a resistance heating rod, a semiconductor temperature control element, or a fluid circulation heating channel. Using the temperature control module, heat can be transferred from the surface of the fixation platform to the test sample adsorbed thereon via thermal conduction.

[0119] S503, Monitor the real-time temperature of the test sample;

[0120] In this embodiment, real-time temperature refers to the actual surface temperature or average body temperature of the test sample at the current moment. The real-time temperature of the test sample can be monitored directly using a K-type thermocouple or a thin-film platinum resistance sensor attached to the surface of the test sample. Alternatively, a non-contact, high-precision infrared thermometer can be used to scan the surface of the test sample in real time to obtain the real-time temperature. To ensure the representativeness of the measurement, the system can select the temperature value at the geometric center of the test sample as the real-time temperature.

[0121] S504. Determine that the real-time temperature is greater than or equal to the target operating temperature.

[0122] In this embodiment of the application, when the real-time temperature is greater than or equal to the target working temperature and the preset heat preservation time is maintained (e.g., 5 minutes), the system determines that the preheating is complete and executes the tensile test step in S104. Otherwise, the tensile test step in S104 is not executed, thereby preventing the test from starting prematurely before the sample reaches the specified thermal state.

[0123] As can be seen, the embodiments of this application simulate a specific thermal working environment by controlling the temperature control module set in the vacuum adsorption fixation platform to heat the test sample and monitor the real-time temperature until it reaches the target working temperature, thereby realizing an accurate evaluation of the interfacial bonding performance between the electrode layer and the separator layer under specific temperature conditions.

[0124] After introducing a temperature variable into the test, how to more reasonably set the target operating temperature is a further concern. To this end, some embodiments of this application propose a scheme using digital simulation technology to assist in determining the target operating temperature. Specifically, obtaining the target operating temperature of the lithium-ion battery includes:

[0125] S601. Obtain the preset design parameters and preset operating condition parameters of the lithium-ion battery. The preset design parameters include the thermal properties data of the positive and negative electrode materials and the cell structure size data. The preset operating condition parameters include the charge and discharge rate data.

[0126] In this embodiment, preset design parameters refer to the inherent physical properties and geometric specifications determined during the battery development stage. The thermophysical properties of the positive and negative electrode materials include, but are not limited to, the specific heat capacity, thermal conductivity, and density of the positive electrode active material, negative electrode active material, current collector, and separator. Cell structure dimensions refer to the length, width, height, tab position, and number of internal electrode layers of the wound or stacked cell. Preset operating condition parameters refer to the load conditions simulating actual battery usage scenarios. Charge / discharge rate data refers to the ratio of charge / discharge current to the battery's rated capacity; for example, 2C indicates discharging at twice the rated capacity current.

[0127] S602. Using the battery electrochemical-thermal coupling simulation model, simulation processing is performed based on preset design parameters and preset operating condition parameters to obtain the predicted temperature change data of the test sample.

[0128] In this embodiment, the battery electrochemical-thermal coupling simulation model refers to a numerical calculation model that integrates charge transport, electrochemical reaction kinetics, and heat conduction principles. This model typically combines a P2D (Pseudo-Two-Dimensional Model) describing porous electrode theory with a three-dimensional heat conduction equation based on the law of energy conservation. Simulation processing refers to the process of solving the above equations using finite element method (FEM) or finite volume method (FVM). Predicted temperature change data refers to the simulation output curve showing the temperature change of the cell's interior or surface over time, or a temperature field distribution cloud map at a specific moment.

[0129] In some embodiments of this application, the simulation processing is specifically implemented as follows: the system imports the cell structure size data into the simulation solver to construct a geometric mesh; assigns the thermal property data of the positive and negative electrode materials to the mesh cells; and inputs the charge / discharge rate data as boundary conditions into the model. The solver calculates the Joule heat, electrochemical reaction heat, and polarization heat generated during the electrochemical reaction process, and substitutes these heat source terms into the heat conduction equation to simulate the generation and diffusion process of heat inside the cell, thereby calculating the real-time temperature response of the test sample throughout the entire charge / discharge cycle and generating predicted temperature change data containing the correspondence between timestamps and temperature values.

[0130] S603. Determine the highest temperature value from the predicted temperature change data and use it as the target operating temperature.

[0131] In this embodiment, the system can traverse all temperature nodes in the predicted temperature change data and use a peak search algorithm to identify the global maximum value, i.e., the highest temperature value, throughout the entire operating cycle. Since high-temperature failure of the adhesive usually occurs at the highest temperature, the system uses this highest temperature value as the target operating temperature for subsequent adhesion strength testing.

[0132] As can be seen, the embodiments of this application utilize the battery electrochemical-thermal coupling simulation model to process the predicted temperature change data based on preset design parameters and preset operating condition parameters, and use the highest temperature value determined from it as the target operating temperature, ensuring that the test thermal environment matches the actual operating limit conditions, thereby improving the guiding value of the adhesion strength test results for battery application safety.

[0133] In some embodiments of this application, an adhesion strength calculation model based on the energy integration principle is proposed, which obtains more representative adhesion strength data through the analysis of force-displacement curves. Specifically, based on applied tensile force data and displacement data, the adhesion strength data of the membrane layer is determined, including:

[0134] S701. Determine the effective peel width of the diaphragm layer based on the physical width dimensions of the first edge region and the second edge region.

[0135] In this embodiment, the physical width of the first edge region refers to the actual geometric width of the area of ​​the membrane layer adsorbed by the first vacuum adsorption module in the vacuum adsorption stretching assembly in the transverse cross section. The physical width of the second edge region refers to the actual geometric width of the area adsorbed by the second vacuum adsorption module in the vacuum adsorption stretching assembly in the transverse cross section. The effective peel width refers to the total linear width of the bus that actually participates in resisting the peel force at the interface during the bilateral symmetrical stretching process.

[0136] In some embodiments of this application, since the embodiments employ a bilateral symmetrical peeling mode that applies tensile force to both the first and second edge regions simultaneously, the adhesive interfaces corresponding to the two regions will separate at the same time. Therefore, the effective peeling width can be obtained by adding the physical width of the first edge region and the physical width of the second edge region. For example, if the physical width of both the first and second edge regions is 20 mm, the effective peeling width is determined to be 40 mm.

[0137] S702. Generate a tension-displacement curve showing the change of applied tension data with displacement data;

[0138] In the embodiments of this application, the tension-displacement curve refers to a two-dimensional relationship graph plotted with the displacement data of the diaphragm layer as the abscissa (X-axis) and the corresponding applied tension data as the ordinate (Y-axis).

[0139] S703. Based on the tension-displacement curve, determine the effective peeling stroke of the diaphragm layer;

[0140] In the embodiments of this application, the effective peeling stroke refers to the length of the displacement interval in the tension-displacement curve that characterizes the stable interface separation process. This interval excludes the elastic tensile deformation of the material at the beginning of the test and the diaphragm breakage or complete detachment at the end of the test.

[0141] In some embodiments of this application, the specific implementation of determining the effective peeling stroke is as follows: The system performs first-order derivative analysis on the force-displacement curve to identify the rate of change of the slope. When the slope of the curve approaches zero for the first time after an initial rise or fluctuates within a certain range, it is marked as the stroke start point; when the applied force data shows an irreversible decrease from the peak plateau segment and the decrease exceeds a preset percentage (e.g., 90%), it is marked as the stroke end point. The system calculates the difference between the displacement value corresponding to the stroke end point and the displacement value corresponding to the stroke start point to obtain the effective peeling stroke. This step ensures that the data involved in the calculation comes only from the actual interface peeling stage.

[0142] S704. The product of the effective peeling stroke and the effective peeling width is taken as the effective peeling area;

[0143] In the embodiments of this application, the effective peel area refers to the equivalent geometric area parameter that characterizes the total workload of interface separation in the calculation model defined in the test.

[0144] S705. Determine the integral area of ​​the tension-displacement curve within the effective peeling stroke to obtain the peeling work data;

[0145] In this embodiment, the integral area refers to the area of ​​the geometric region enclosed by the force-displacement curve and the horizontal axis, and its physical meaning is the mechanical work done by the external force. The peeling work data refers to the total energy consumed to overcome the interfacial intermolecular forces and mechanical interlocking forces between the separator layer and the electrode layer within the effective peeling stroke, measured in joules.

[0146] In some embodiments of this application, the specific implementation of obtaining the stripping work data is as follows: the system uses numerical integration algorithms such as the Trapezoidal Rule to perform definite integral calculations on the tension-displacement curve within the effective stripping stroke range. Compared with calculation methods that only take a single peak force, the stripping work data based on energy integration can encompass the force fluctuation information during the stripping process, and more comprehensively reflect the toughness and resistance to damage of the interfacial bonding between the diaphragm layer and the electrode layer.

[0147] S706. Determine the adhesion strength data based on the ratio of peeling work data to effective peeling area.

[0148] In this embodiment, the adhesion strength data can be obtained by dividing the peeling work data by the effective peeling area. Furthermore, the system can output the adhesion strength data to a display terminal or generate a test report based on the adhesion strength data for review by relevant technical personnel.

[0149] As can be seen, the embodiments of this application obtain the peeling work data by determining the integral area of ​​the tension-displacement curve within the effective peeling stroke, and calculate its ratio with the effective peeling area, thereby transforming the dynamically changing force response into a normalized index that can characterize the interface energy dissipation characteristics, thus reflecting the interfacial bonding ability of the membrane layer more comprehensively.

[0150] In other embodiments of this application, an alternative method for determining adhesion strength data is provided. After step S705, adhesion strength data can also be calculated using a first-order plastic dissipation correction model built into the system. Specifically, considering that the current collector of the electrode layer (such as copper foil or aluminum foil) absorbs the plastic strain energy of the metal itself under forced bending release angle, the system calculates the anti-warping mechanical work parameter corresponding to bending a metal foil of that thickness individually using the Euler-Bernoulli Beam bending analytical formula. Before calculating the ratio, the system removes the anti-warping mechanical work parameter from the peeling work data, and then performs a division operation with the effective peeling area to determine the adhesion strength data that reflects the purity of the true van der Waals force adsorption binding energy level between the peeled electrode adhesive (such as styrene-butadiene rubber, SBR) and the separator.

[0151] In this embodiment, adhesion strength data specifically refers to the actual physical quantity characterizing the microscopic interface bonding energy level between the diaphragm layer and the electrode layer after substrate deformation energy decoupling processing. The first-order plastic dissipation correction model is a numerical calculation algorithm based on the principles of continuum mechanics, used to quantify and peel off the irreversibly consumed mechanical energy due to plastic bending of the metal current collector during the peeling process. The Euler-Bernoulli beam bending analytical equation is a differential equation describing the deflection and deformation behavior of a beam under load; here, it is used to calculate the strain energy of the electrode layer current collector (such as copper foil or aluminum foil) at the forced bending separation angle. The anti-warping mechanical work parameter refers to the total metal plastic strain energy absorbed by the electrode layer current collector as it is forced to bend from a straight state to the peeling angle state within the effective peeling stroke.

[0152] The specific steps for determining adhesion strength data include:

[0153] First, the system acquires the preset material property parameters of the current collector in the electrode layer of the test sample. These parameters include the physical thickness of the current collector, Young's modulus, and yield strength. For example, for the negative electrode, the system retrieves the thickness and mechanical parameters of the copper foil; for the positive electrode, the system retrieves the thickness and mechanical parameters of the aluminum foil.

[0154] Secondly, the system invokes the built-in first-order plastic dissipation correction model. Considering the drastic curvature change experienced by the current collector in the electrode layer at the peeling front region, the system calculates the maximum bending curvature of the current collector in the peeling bending zone based on the Euler-Bernoulli beam bending analytical formula. The system determines the elastoplastic boundary within the current collector cross-section based on the yield strength, integrates the stress-strain curve in the plastic region, and calculates the plastic dissipation energy density per unit length. The system integrates this energy density over the entire effective peeling stroke to calculate the anti-warping mechanical work parameters corresponding to bending a metal foil of that thickness individually.

[0155] Next, the system performs an energy decoupling operation. The system subtracts the calculated anti-warping mechanical work parameter from the peeling work data obtained in step S705 to obtain the corrected interface peeling work. This step eliminates the excess anti-warping mechanical work parameter, thus eliminating the artificially high contribution of the plastic deformation of the metal substrate to the test results.

[0156] Finally, the system divides the corrected interface peeling work with the effective peeling area obtained in step S704 to determine the adhesion strength data of the true van der Waals force adsorption binding energy level purity between the peeled-off electrode adhesive (such as styrene-butadiene rubber, SBR) and the separator.

[0157] As can be seen, the embodiments of this application successfully removed the anti-warping mechanical work parameter consumed by the deformation of the current collector from the total peeling work data by using the first-order plastic dissipation correction model and the Euler-Bernoulli beam bending analytical formula, thereby achieving physical noise reduction processing of the adhesion strength data. This allows the final result to accurately characterize the van der Waals adsorption bonding energy level between the electrode adhesive and the separator layer, avoiding interference from the plastic deformation properties of the metal current collector on the evaluation of the interface bonding quality.

[0158] In some embodiments of this application, the Euler-Bernoulli beam model typically assumes that the material is ideally elastoplastic or linearly elastic, neglecting the significant work hardening effect of the metal current collector (especially rolled copper or aluminum foil) when subjected to large-angle, severe bending. However, in actual industrial scenarios, the metal foil undergoes intense plastic flow at the peel root, and its yield strength dynamically increases with deformation, leading to an underestimation of the "anti-bending mechanical work" calculated by the original model, resulting in an overestimation (incomplete purity) of the final calculated adhesion strength. Therefore, after determining the corrected interfacial peel work, the model may further include:

[0159] S801. Divide the corrected interfacial peeling work by the effective peeling area to obtain the total macroscopic peeling strength, which includes interfacial energy and plastic work.

[0160] In the embodiments of this application, the total macroscopic peel strength, which includes interfacial energy and plastic work, refers to the total energy consumption per unit area. Its physical composition includes both the interfacial adhesion energy used to break the molecular bonding forces between the separator layer and the electrode layer, and the irreversible plastic deformation work consumed in bending the metal current collector (such as copper foil or aluminum foil) from a flat state to the peel angle. Although this value reflects the overall resistance of the peeling process, it is greatly affected by the thickness and hardness of the current collector and has not yet reached the purity required to characterize the intrinsic properties of the interface.

[0161] S802, Introducing a second-order nonlinear strain hardening dynamic compensation algorithm based on the Ramberg-Osgood constitutive equation;

[0162] In this embodiment, the Lamberg-Osgood constitutive equation is a mathematical model describing the nonlinear relationship between stress and strain in ductile metallic materials during the plastic deformation stage. The second-order nonlinear strain hardening dynamic compensation algorithm refers to the calculation logic that uses this equation to calculate the additional plastic work generated by the dynamic increase in material hardness (i.e., work hardening) as the deformation increases after the yield point. Here, "second-order" refers to a second-order refined correction to the relationship between curvature and bending moment.

[0163] In some embodiments of this application, in step S802, the system loads the algorithm module into memory and initializes the material constants of the current collector, including the elastic modulus, yield strength, hardening coefficient, and strain hardening exponent. Compared to a first-order model assuming ideal elastic-plastic properties, this algorithm can accurately simulate the real mechanical behavior of metal foils when bent at large angles, preventing underestimation of plastic work due to neglecting work hardening effects.

[0164] S803: Call the camera unit to capture the instantaneous bending radius of the peeled root in real time, and calculate the elastic-plastic bending moment of the current collector under the current curvature by combining the preset current collector material parameters.

[0165] In this embodiment, the camera unit may be a high-speed industrial camera with its optical axis perpendicular to the peeling direction and equipped with dual telecentric lenses. It possesses optical characteristics of constant magnification within the depth of field, enabling the elimination of parallax distortion. The peeling root refers to the crack tip region where the electrode layer and diaphragm layer are separating.

[0166] The instantaneous bending radius of curvature refers to the geometric radius at the point where the current collector experiences maximum bending deformation at the peeling root. The elastoplastic bending moment refers to the internal moment generated by the current collector cross-section to resist bending deformation. The system can combine preset current collector material parameters (such as thickness, elastic modulus, strain hardening index) and substitute the instantaneous bending radius of curvature into the moment-curvature relationship derived from the Lamberg-Osgood equation to numerically solve for the elastoplastic bending moment on the current current current collector cross-section.

[0167] S804. Perform path integral of the elastic-plastic bending moment with respect to the curvature change to calculate the plastic dissipation work density of the current collector per unit area.

[0168] In this embodiment, path integral refers to the integral calculation along the loading-unloading path of the current collector, from a straight state (curvature of 0) to the maximum curvature, and then back to the residual curvature. Plastic dissipation work density of the current collector refers to the energy loss per unit area of ​​the current collector due to plastic bending, measured in joules per square meter.

[0169] S805. Subtract the current collector plastic dissipation work density from the total macroscopic peel strength to obtain the adhesion strength data after nonlinear hardening correction.

[0170] In the embodiments of this application, the adhesion strength data after nonlinear hardening correction refers to a physical quantity that eliminates the interference of metal substrate deformation and only characterizes the strength of the interfacial chemical bonding and mechanical interlocking between the coating and the membrane.

[0171] As can be seen, the embodiments of this application construct a second-order nonlinear strain hardening dynamic compensation model by introducing the Lamberg-Osgood constitutive equation and the real-time visual curvature feedback mechanism. This model considers the plastic dissipation work generated by the work hardening effect during the large deformation peeling process of the metal current collector, thereby enabling the extraction of more accurate intrinsic adhesion strength data of the interface from the macroscopic test data and eliminating the interference of the current collector material difference on the evaluation results.

[0172] In some embodiments of this application, the scheme of "driving the first vacuum adsorption module in the vacuum adsorption stretching assembly to move relative to the second vacuum adsorption module" may further include the following details:

[0173] S901. Obtain the first angle between the stretching axis direction of the first vacuum adsorption module and the normal direction of the first adsorption area of ​​the vacuum adsorption fixing platform, and the second angle between the stretching axis direction of the second vacuum adsorption module and the normal direction of the second adsorption area of ​​the vacuum adsorption fixing platform.

[0174] In this embodiment, the first vacuum adsorption module and the second vacuum adsorption module refer to two independent and controllable motion units in the vacuum adsorption stretching assembly, respectively used to adsorb the two ends of the membrane layer. The first included angle and the second included angle characterize the spatial attitude deviation of the two independent adsorption units relative to the vacuum adsorption fixed platform.

[0175] S902. Determine the first angle deviation value between the first included angle and the preset vertical stretching direction, and the second angle deviation value between the second included angle and the preset vertical stretching direction, and adjust the postures of the first vacuum adsorption module and the second vacuum adsorption module respectively until the first angle deviation value and the second angle deviation value are both within the preset tolerance range.

[0176] In the embodiments of this application, the angle deviation value refers to the vector difference between the measured stretching direction and the ideal peeling direction (usually vertically upward or along the horizontal tangent direction).

[0177] S903. Obtain the preset tensile test speed and total tensile stroke for the test sample;

[0178] In this embodiment, the tensile test speed refers to the relative approach speed of the first vacuum adsorption module toward the second vacuum adsorption module. The total tensile stroke refers to the sum of the expected relative displacements of the first vacuum adsorption module toward the second vacuum adsorption module when the peeling process is completed.

[0179] S904. Generate the target speed-time control curve based on the tensile test speed and total tensile stroke;

[0180] In this embodiment of the application, the specific implementation of generating the target speed-time control curve is as follows: the system constructs a virtual spindle and generates a main speed curve that satisfies the total stretching stroke for the virtual spindle based on the S-shaped speed planning algorithm, thereby obtaining the target speed-time control curve.

[0181] S905. Drive the first vacuum adsorption module to move relative to the second vacuum adsorption module at a preset low-speed pre-tensioning speed, and detect the first applied tension data and the second applied tension data respectively. Then determine whether the first applied tension data is greater than or equal to the preset first tension threshold and whether the second applied tension data is greater than or equal to the preset second tension threshold.

[0182] S906. If the judgment result is yes, mark the current time as the stretching start point and reset the displacement encoder value of the first vacuum adsorption module to zero.

[0183] S907. Based on the target speed-time control curve of the virtual spindle, drive the first vacuum adsorption module into a uniform stretching state.

[0184] S908. Determine the sum of the first applied tension data and the second applied tension data, and use it as the applied tension data of the vacuum adsorption stretching component on the first edge region and the second edge region; and determine the displacement of the first vacuum adsorption module, and use it as the displacement data of the diaphragm layer.

[0185] As can be seen, the embodiment of this application for the scheme of "driving the first vacuum adsorption module in the vacuum adsorption stretching assembly to move relative to the second vacuum adsorption module" also achieves precise symmetrical peeling of the two sides of the membrane layer, so as to improve the stability of the adhesion strength detection and make the obtained adhesion strength data more accurate.

[0186] Secondly, embodiments of this application provide an adhesion strength detection system for lithium-ion battery separators, which is used to perform the adhesion strength detection method for lithium-ion battery separators as described in any of the above embodiments.

[0187] Thirdly, embodiments of this application provide an electronic device that integrates any of the lithium-ion battery separator adhesion strength detection systems provided in the embodiments of this application, and is capable of operating such a system. The electronic device may further include a memory, a processor, and a computer program stored in the memory. The processor executes the computer program to run any of the lithium-ion battery separator adhesion strength detection systems provided in the embodiments of this application, thereby implementing the lithium-ion battery separator adhesion strength detection method as described in any of the above embodiments.

[0188] Fourthly, embodiments of this application provide an electronic device that integrates any of the lithium-ion battery separator adhesion strength detection systems provided in embodiments of this application, and is capable of operating such a system. For example... Figure 5 As shown, it illustrates a structural schematic diagram of the electronic device involved in the embodiments of this application, specifically:

[0189] The electronic device includes a Central Processing Unit (CPU) 501, which can perform various appropriate actions and processes based on a program stored in Read-Only Memory (ROM) 502 or a program loaded from storage portion 508 into Random Access Memory (RAM) 503, such as performing the methods described in the above embodiments. The RAM 503 also stores various programs and data required for system operation. The CPU 501, ROM 502, and RAM 503 are interconnected via a bus 504. An Input / Output (I / O) interface 505 is also connected to the bus 504.

[0190] The following components are connected to I / O interface 505: input section 506 including audio input devices, push-button switches, etc.; output section 507 including a liquid crystal display (LCD) and audio output devices, indicator lights, etc.; storage section 508 including a hard disk, etc.; and communication section 509 including a network interface card such as a LAN (Local Area Network) card, modem, etc. Communication section 509 performs communication processing via a network such as the Internet. Drive 510 is also connected to I / O interface 505 as needed. Removable media 511, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., are installed on drive 510 as needed so that computer programs read from them can be installed into storage section 508 as needed.

[0191] Specifically, according to embodiments of this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program including a computer program for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication section 509, and / or installed from removable medium 511. When the computer program is executed by central processing unit (CPU) 501, it performs the various functions defined in this application.

[0192] It should be noted that specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), flash memory, optical fiber, portable compact disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing. In this application, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0193] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. Each block in a flowchart or block diagram may represent a module, segment, or portion of code, which contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those shown in the drawings.

[0194] Specifically, the electronic device of this embodiment includes a processor and a memory. The memory is coupled to one or more processors and is used to store computer program code. The computer program code includes computer instructions. One or more processors call the computer instructions to cause the electronic device to perform the method provided in the above embodiment.

[0195] Fifthly, embodiments of this application provide a computer-readable storage medium storing a computer program configured to be executed by a processor to implement the method for detecting the adhesion strength of a lithium-ion battery separator as described in any of the above embodiments.

[0196] Sixthly, embodiments of this application provide a computer program product, including a computer program or instructions, which are executed by a processor to implement the adhesion strength detection method for lithium-ion battery separators as described in any of the preceding claims.

[0197] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for detecting the adhesion strength of a lithium-ion battery separator, characterized in that, The method for detecting the adhesion strength of the lithium-ion battery separator includes: Provide a test sample after hot pressing pretreatment, the test sample comprising an electrode layer and a separator layer bonded together, the test sample being used in a lithium-ion battery; The electrode layer is fixed by adsorbing it using a vacuum adsorption fixation platform; Using a vacuum adsorption stretching assembly, the first edge region and the second edge region of the surface of the diaphragm layer facing away from the electrode layer are adsorbed. The first edge region and the second edge region are located at opposite ends of the surface and are symmetrically arranged with respect to the center point of the surface. The vacuum adsorption stretching assembly is driven to move away from the vacuum adsorption fixing platform, or the first vacuum adsorption module in the vacuum adsorption stretching assembly is driven to move relative to the second vacuum adsorption module, so as to apply tension to the first edge region and the second edge region simultaneously. The first vacuum adsorption module is used to adsorb the first edge region, and the second vacuum adsorption module is used to adsorb the second edge region. During the process of driving the vacuum adsorption stretching component to move away from each other or to move relative to each other, the tensile force data applied by the vacuum adsorption stretching component to the first edge region and the second edge region, as well as the displacement data of the membrane layer, are collected. Based on the applied tensile force data and the displacement data, the adhesion strength data of the membrane layer is determined.

2. The method for detecting the adhesion strength of a lithium-ion battery separator as described in claim 1, characterized in that, The method of driving the vacuum adsorption stretching assembly to move away from the vacuum adsorption fixing platform includes: Obtain the preset tensile test speed and total tensile stroke for the test sample; Based on the tensile test speed and the total tensile stroke, a target speed-time control curve is generated, which includes an acceleration segment, a constant speed segment and a deceleration segment connected in sequence. According to the target speed-time control curve, the vacuum adsorption stretching assembly is driven to move away.

3. The method for detecting the adhesion strength of a lithium-ion battery separator as described in claim 2, characterized in that, The step of driving the vacuum adsorption stretching assembly to move away according to the target speed-time control curve includes: The vacuum adsorption stretching assembly is driven to move away at a preset low pre-tension speed, and the current applied tension in the applied tension data is detected to be greater than or equal to a preset tension threshold. If the current applied tension is greater than or equal to the tension threshold, the current moment is marked as the starting point of the tension, and the collected displacement data is reset to zero. Based on the S-shaped speed planning algorithm, a smooth acceleration curve is generated from the low-speed pre-tension speed to the constant speed segment speed. The vacuum adsorption stretching component is driven to move away according to the smooth acceleration curve, so that the moving away motion of the vacuum adsorption stretching component switches from the acceleration segment to the uniform speed segment.

4. The method for detecting the adhesion strength of a lithium-ion battery separator as described in claim 2, characterized in that, Before driving the vacuum adsorption stretching assembly to move away, the method further includes: Obtain the current angle between the stretching axis direction of the vacuum adsorption stretching assembly and the normal direction of the adsorption surface of the vacuum adsorption fixing platform; Determine the angular deviation value between the current included angle and the preset vertical stretching direction; Adjust the direction of the stretching axis according to the angle deviation value so that the direction of the stretching axis coincides with the normal direction of the adsorption surface; The vacuum adsorption stretching assembly is set to move away from the direction of the adjusted stretching axis.

5. The method for detecting the adhesion strength of a lithium-ion battery separator as described in claim 1, characterized in that, Before driving the vacuum adsorption stretching assembly to move away from the vacuum adsorption fixing platform, or driving the first vacuum adsorption module in the vacuum adsorption stretching assembly to move relative to the second vacuum adsorption module, the method further includes: Obtain the target operating temperature of the lithium-ion battery; The temperature control module, located within the vacuum adsorption fixation platform, heats the test sample. Monitor the real-time temperature of the test sample; The real-time temperature is determined to be greater than or equal to the target operating temperature.

6. The method for detecting the adhesion strength of a lithium-ion battery separator as described in claim 5, characterized in that, The process of obtaining the target operating temperature of the lithium-ion battery includes: Obtain the preset design parameters and preset operating condition parameters of the lithium-ion battery. The preset design parameters include thermal property data of positive and negative electrode materials and cell structure size data. The preset operating condition parameters include charge and discharge rate data. Using a battery electrochemical-thermal coupling simulation model, simulation processing is performed based on the preset design parameters and the preset operating condition parameters to obtain the predicted temperature change data of the test sample; The highest temperature value is determined from the predicted temperature change data and used as the target operating temperature.

7. The method for detecting the adhesion strength of a lithium-ion battery separator as described in claim 1, characterized in that, The determination of the adhesion strength data of the membrane layer based on the applied tensile force data and the displacement data includes: The effective peel width of the diaphragm layer is determined based on the physical width dimensions of the first edge region and the second edge region. Generate a tension-displacement curve showing the change of the applied tension data as a function of the displacement data; Based on the tension-displacement curve, the effective peeling stroke of the diaphragm layer is determined; The effective peeling area is the product of the effective peeling stroke and the effective peeling width. The integral area of ​​the tension-displacement curve within the effective peeling stroke is determined to obtain the peeling work data; The adhesion strength data is determined based on the ratio of the peeling work data to the effective peeling area.

8. A system for detecting the adhesion strength of a lithium-ion battery separator, characterized in that, The adhesion strength testing system for lithium-ion battery separators is used to perform the adhesion strength testing method for lithium-ion battery separators according to any one of claims 1 to 7.

9. An electronic device, characterized in that, The electronic device includes a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the method for detecting the adhesion strength of a lithium-ion battery separator according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program configured to be executed by a processor to implement the adhesion strength detection method for the lithium-ion battery separator according to any one of claims 1 to 7.

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