A method and device for detecting positive electrode sheet layer peeling strength

Abstract

The application provides a positive electrode sheet layer peeling strength detection method and device, which comprises the following steps: obtaining a to-be-detected positive electrode sheet, a first bottom plate, and a second bottom plate; bonding the to-be-detected positive electrode sheet, the first bottom plate, and the second bottom plate to form a to-be-detected structure containing the positive electrode sheet; fixing the to-be-detected structure at both ends of a tensile tester; starting the tensile tester to perform a peeling test on the to-be-detected structure to obtain the layer peeling force of the to-be-detected positive electrode sheet, so as to realize the detection of the layer peeling strength of the to-be-detected positive electrode sheet; bonding the to-be-detected positive electrode sheet and the first bottom plate together and folding the to-be-detected positive electrode sheet to form a bending part; bonding the bending part and the second bottom plate together to form a to-be-detected structure; and detecting the to-be-detected structure based on the tensile tester to obtain the layer peeling strength of the to-be-detected positive electrode sheet.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of lithium ion batteries, in particular to a cathode sheet material layer peeling strength detection method and device. BACKGROUND

[0002] In the development process of power lithium ion batteries, continuously improving specific energy is an important development index. High loading capacity and high compaction density design are important technical measures to improve the energy density of single units (ternary system: areal density > 22 mg / cm2, compaction density > 3.4 g / cm3, lithium iron phosphate system: areal density > 28 mg / cm2, > 2.8 g / cm3). However, high loading capacity and high compaction density design cause great difficulty in evaluating the internal adhesion state of the sheet material layer, especially the adhesion properties of the material layer at the bending part of the wound sheet. The main problem is that high loading capacity means thick electrode design, which will generate higher coating cohesion force than peeling force when bending, and after high-strength rolling, the brittleness of the aluminum foil current collector increases sharply, so the conventional 180° bidirectional tensile test method easily causes the current collector to break, resulting in test interruption, and the internal peeling strength of the sheet material layer cannot be accurately characterized, which limits the further optimization of the sheet processing performance and the stability of the material layer, especially the evaluation of the material layer peeling strength at the bending part of the wound cell structure, which affects the improvement of the battery technology.

[0003] A test method for testing the peeling strength of a lithium ion battery cathode sheet is provided in patent CN109870353A. The inventor adheres one side of the double-sided adhesive tape to a steel plate and adheres the other side to the lower part of the pad film, and adheres the upper part to the coating of the sheet. Then the lower end of the sheet is fixed to the first end of the tensile tester, the steel plate is fixed to the second end of the tensile tester, the coating is directly peeled off by the tensile tester, and the test is performed. This method is simple and easy to operate, but for some sheets with high compaction density, the sheet sample is prone to break when folded at 180°, so that effective peeling strength data cannot be obtained, and therefore the above method cannot accurately test the peeling strength of the cathode sheet material layer while effectively testing and evaluating the bending part of the wound sheet. SUMMARY

[0004] In view of the above technical defects, the application provides a cathode sheet material layer peeling strength detection method and device to solve the technical problem that the above method cannot accurately test the peeling strength of the cathode sheet material layer while effectively testing and evaluating the bending part of the wound sheet.

[0005] The application provides a positive electrode sheet layer peeling strength detection method, which comprises the following steps: obtaining a to-be-detected positive electrode sheet, a first bottom plate and a second bottom plate; bonding the to-be-detected positive electrode sheet, the first bottom plate and the second bottom plate to form a to-be-detected structure containing the positive electrode sheet; fixing the to-be-detected structure at two ends of a tensile tester; starting the tensile tester to perform a peeling test on the to-be-detected structure, so as to obtain the layer peeling force of the to-be-detected positive electrode sheet, thereby realizing detection of the layer peeling strength of the to-be-detected positive electrode sheet.

[0006] In an embodiment of the application, before the to-be-detected positive electrode sheet is obtained, the method further comprises the following steps: coating positive electrode slurry on an aluminum foil current collector to form a single-sided positive electrode sheet; cutting the single-sided positive electrode sheet based on a first preset size to obtain a to-be-processed positive electrode sheet; bonding a carbon fiber cloth to one side of the to-be-processed positive electrode sheet to form a composite electrode sheet; and compacting the composite electrode sheet to a preset density threshold to obtain the to-be-detected electrode sheet.

[0007] In an embodiment of the application, bonding the to-be-detected positive electrode sheet, the first bottom plate and the second bottom plate to form a to-be-detected structure containing the positive electrode sheet comprises the following steps: cutting the to-be-detected positive electrode sheet based on a second preset size; connecting one side of the cut to-be-detected positive electrode sheet to the first bottom plate to obtain a first connecting body, and folding the first connecting body to form a bending part; and bonding one end of the second bottom plate to the bending part to form the to-be-detected structure.

[0008] In an embodiment of the application, connecting one side of the cut to-be-detected positive electrode sheet to the first bottom plate to obtain a first connecting body comprises the following steps: determining a sheet center of the to-be-detected positive electrode sheet, and dividing the to-be-detected positive electrode sheet into two ends along the sheet center; bonding the first bottom plate to any side of the to-be-detected positive electrode sheet, wherein the length of the first bottom plate is greater than half the length of the to-be-detected positive electrode sheet; and folding the to-be-detected positive electrode sheet along the sheet center, so that the to-be-detected positive electrode sheet is bonded on both sides of the first bottom plate to form the first connecting body.

[0009] In an embodiment of the application, fixing the to-be-detected structure at two ends of a tensile tester comprises the following steps: fixing one end of the first connecting body, which is away from the bending part, to one end of the tensile tester; and fixing one end of the second bottom plate, which is away from the bending part, to the other end of the tensile tester.

[0010] In an embodiment of the present application, the tensile tester is started to perform a peeling light test on the to-be-tested structure to obtain the layer peeling force of the to-be-tested positive plate, comprising: setting parameters of the tensile tester and starting the tensile tester; recording the tensile force value in the tensile tester test process to obtain the layer peeling force of the to-be-tested positive plate.

[0011] In an embodiment of the present application, the coating process of coating the positive electrode slurry on the aluminum foil current collector includes any one of transfer type, doctor blade, and spray type.

[0012] In an embodiment of the present application, the to-be-tested positive plate, the first bottom plate, and the second bottom plate are bonded based on double-sided adhesive, and the width of the double-sided adhesive is equal to the width of the to-be-tested positive plate, the width of the first bottom plate is greater than or equal to the width of the to-be-tested positive plate, and the width of the second bottom plate is greater than or equal to the width of the to-be-tested positive plate.

[0013] The present application provides a positive plate layer peeling strength detection device, which comprises: a material configuration module for preparing a to-be-tested positive plate, a first bottom plate, and a second bottom plate; a to-be-tested structure generation module for bonding the to-be-tested positive plate, the first bottom plate, and the second bottom plate to form a to-be-tested structure containing a positive plate; and a peeling strength detection module for fixing the to-be-tested structure at both ends of a tensile tester and starting the tensile tester to perform a peeling strength test on the to-be-tested structure to obtain the layer peeling force of the to-be-tested positive plate, thereby realizing detection of the layer peeling strength of the to-be-tested positive plate.

[0014] In an embodiment of the present application, the peeling strength detection module comprises: a tensile tester unit for detecting the layer peeling force of the to-be-tested positive plate; a sensor unit for sending the layer peeling force data of the tensile tester to a data processing unit; and a data processing unit for generating a load-travel peeling curve based on the obtained layer peeling force data.

[0015] The application provides a positive electrode sheet material layer peeling strength detection method and device.

[0016] In addition, the positive electrode sheet material layer peeling strength detection method and device can effectively evaluate the peeling strength of a high-load, high-compaction electrode sheet, especially a winding electrode sheet bending part, improve the accuracy and stability of test data, and provide reference data for electrode sheet adhesion strength related material selection, formula optimization, process improvement and the like.

[0017] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and are not limiting to the application. BRIEF DESCRIPTION OF DRAWINGS

[0018] The drawings incorporated into the specification and forming a part thereof show embodiments consistent with the application and serve to explain the principles of the application. It is apparent that the drawings described below are only some embodiments of the application, and other drawings can be obtained by those of ordinary skill in the art without creative labor on the basis of these drawings. In the drawings:

[0019] Figure 1 is a schematic diagram of an implementation environment of the positive electrode sheet material layer peeling strength detection method according to an example embodiment of the application;

[0020] Figure 2 is a flowchart of the positive electrode sheet material layer peeling strength detection method according to an example embodiment of the application;

[0021] Figure 3 is a flowchart of the positive electrode sheet material layer peeling strength detection method according to an example embodiment of the application;

[0022] Figure 4 is a schematic diagram of the electrode sheet structure characteristics of Example 1 according to an example embodiment of the application;

[0023] Figure 5 is a schematic diagram of the peeling test of Example 1 according to an example embodiment of the application;

[0024] Figure 6 Figure 1 is a load-displacement peel curve of Example 1, according to an example embodiment of the present application;

[0025] Figure 7 Figure 2 is a schematic diagram of the structure of the positive electrode tab of Comparative Example 1, according to an example embodiment of the present application;

[0026] Figure 8 Figure 3 is a schematic diagram of the peel test of Comparative Example 1, according to an example embodiment of the present application;

[0027] Figure 9 Figure 4 is a load-displacement peel curve of Comparative Example 1, according to an example embodiment of the present application;

[0028] Figure 10 Figure 5 is a photograph of the state of the positive electrode tab after peeling of Example 1 and Comparative Example 1, according to an example embodiment of the present application;

[0029] Figure 11 Figure 6 is a block diagram of a device for measuring the positive electrode tab layer peel strength, according to an example embodiment of the present application. DETAILED DESCRIPTION

[0030] Other advantages and effects of the present application will be easily understood by those skilled in the art from the description of the preferred embodiments of the present application. The present application can be implemented or applied in other different specific embodiments, and the details in the description can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be understood that the preferred embodiments are only for illustrating the present application, and are not intended to limit the scope of protection of the present application.

[0031] It should be noted that the diagrams provided in the following embodiments only schematically illustrate the basic concept of the present application, and only the components related to the present application are shown in the diagrams, rather than the number, shape and size of the components when actually implemented. The actual implementation of each component can be a random change in type, number and proportion, and the layout type of the components can be more complex.

[0032] In the following description, a large number of details are discussed to provide a more thorough explanation of the embodiments of the present application, however, it is obvious to those skilled in the art that the embodiments of the present application can be implemented without these specific details, and in other embodiments, the known structures and devices are shown in the form of block diagrams rather than in the form of details, to avoid making the embodiments of the present application difficult to understand.

[0033] First of all, it needs to be pointed out that the current collector, as the name implies, refers to the structure or part that collects current, mainly refers to metal foils such as copper foil and aluminum foil on lithium-ion batteries. It can also include tabs in general. Its function is mainly to collect the current generated by the battery active material to form a larger current output externally, so the current collector should be in full contact with the active material, and the internal resistance should be as small as possible.

[0034] Figure 1 is a schematic diagram of the implementation environment of the positive electrode sheet layer peeling strength detection method shown in an exemplary embodiment of the present application. As shown in Figure 1 , the implementation environment of the positive electrode sheet layer peeling strength detection method includes a tension detection device 101 and a computing device 102, wherein the tension detection device is used to detect the force of the structure to be detected during the peeling process, including but not limited to a tensile tester or a tensile machine and other any device or apparatus capable of detecting tension. The computer device 102 can be at least one of a desktop graphic processing unit (GPU) computer, a GPU computing cluster, a neural network computer, etc., and can also be an intelligent processor integrated on the current vehicle. Related technical personnel can send the tension value obtained by the tension detection device to the computer device 102 through the sensor device, and based on the computer device 102, the obtained tension value is calculated and processed to obtain the layer peeling strength of the positive electrode sheet to be detected.

[0035] Figure 2 is a flowchart of the positive electrode sheet layer peeling strength detection method according to an exemplary embodiment of the present application. As shown in Figure 2 , in an exemplary embodiment, the positive electrode sheet layer peeling strength detection method includes at least steps S210 to S230, which are described in detail as follows:

[0036] Step S210, obtaining a positive electrode sheet to be detected, a first bottom plate, and a second bottom plate.

[0037] In an embodiment of the present application, before obtaining the positive electrode sheet to be detected, the method further includes: coating the positive electrode slurry on the aluminum foil current collector to form a single-sided positive electrode sheet; cutting the single-sided positive electrode sheet based on the first preset size to obtain a positive electrode sheet to be processed; bonding the carbon fiber cloth to one side of the positive electrode sheet to be processed to form a composite electrode sheet; and compacting the composite electrode sheet to a preset density threshold to obtain the positive electrode sheet to be detected.

[0038] In an embodiment of the present application, the homogenized positive electrode slurry is first coated on the aluminum foil current collector by a coating process to form a single-sided high-load positive electrode sheet with a designed surface density; then the single-sided high-load positive electrode sheet is cut to a certain size and double-sided adhesive tape is pasted on the back, wherein the size of the double-sided adhesive tape is smaller than that of the single-sided electrode sheet; then the tough layer material is taken and pasted on the back of the single-sided electrode sheet to form a composite electrode sheet, wherein the size of the tough layer is not greater than that of the electrode sheet; finally, the designed compaction density is achieved by a rolling process to obtain the final electrode sheet to be tested.

[0039] It should be noted that the coating process of coating the positive electrode slurry on the aluminum foil current collector includes any one of transfer type, doctor blade, and spray type. The positive electrode sheet is characterized in that its components include a positive electrode coating layer and an aluminum foil current collector, and the positive electrode coating layer includes a positive electrode material, a conductive agent, and a binder. The positive electrode material includes but is not limited to the following materials: ternary material, lithium cobaltate, lithium iron phosphate, lithium manganate, lithium iron manganate, lithium-rich manganese-based, 5V spinel material, etc.; the conductive agent includes any one or combination of carbon black, ketjen black, carbon nanotube, and graphene; the binder is any one of PVDF or PTFE; in addition, the tough layer is characterized in that the tough layer is composed of any one of non-woven fabric, carbon fiber non-woven fabric, metal mesh, and PET film, which can release stress under high compaction density conditions, enhance the tensile strength of the aluminum foil, and improve the bending toughness, and can support the peeling strength test of the active material layer at the bending position of the electrode sheet.

[0040] It should also be noted that the above-mentioned coating process, positive electrode material, conductive agent, and tough layer are only exemplary and do not limit the protection scope of the present application.

[0041] Step S220, bonding the positive electrode sheet to be tested, the first bottom plate, and the second bottom plate to form a structure to be tested containing the positive electrode sheet.

[0042] In an embodiment of the present application, bonding the positive electrode sheet to be tested, the first bottom plate, and the second bottom plate to form a structure to be tested containing the positive electrode sheet includes: cutting the positive electrode sheet to be tested based on a second predetermined size; connecting one side of the cut positive electrode sheet to be tested to the first bottom plate to obtain a first connection body, and folding the first connection body to form a bending position; bonding one end of the second bottom plate to the bending position to form the structure to be tested.

[0043] In an embodiment of the present application, one side of the cut positive electrode sheet to be detected is connected with the first bottom plate to obtain a first connecting body, comprising: determining the electrode sheet center of the positive electrode sheet to be detected, and dividing the positive electrode sheet to be detected into two ends along the electrode sheet center; bonding the first bottom plate to any side of the positive electrode sheet to be detected, the length of the first bottom plate being greater than half the length of the positive electrode sheet to be detected; folding the positive electrode sheet to be detected along the electrode sheet center, so that the positive electrode sheet to be detected is bonded on both sides of the first bottom plate to form the first connecting body.

[0044] In an embodiment of the present application, the positive electrode sheet to be detected, the first bottom plate, and the second bottom plate are bonded based on the double-sided adhesive, and the width of the double-sided adhesive is equal to the width of the positive electrode sheet to be detected, the width of the first bottom plate is greater than or equal to the width of the positive electrode sheet to be detected, and the width of the second bottom plate is greater than or equal to the width of the positive electrode sheet to be detected.

[0045] In step S230, the structure to be detected is fixed at both ends of the tensile tester, and the tensile tester is started to perform a peeling test on the structure to be detected to obtain the layer peeling force of the positive electrode sheet to be detected, so as to realize the detection of the layer peeling strength of the positive electrode sheet to be detected.

[0046] In an embodiment of the present application, the structure to be detected is fixed at both ends of the tensile tester, comprising: fixing one end of the first connecting body away from the bending part to one end of the tensile tester; and fixing one end of the second bottom plate away from the bending part to the other end of the tensile tester.

[0047] In an embodiment of the present application, the tensile tester is started to perform a peeling test on the structure to be detected to obtain the layer peeling force of the positive electrode sheet to be detected, comprising: setting the parameters of the tensile tester and starting the tensile tester; and recording the tensile force value in the test process of the tensile tester to obtain the layer peeling force of the positive electrode sheet to be detected.

[0048] In an embodiment of the present application, the positive electrode sheet layer peeling strength detection method comprises the following steps:

[0049] S310, taking the positive electrode sheet to be detected to make an electrode sheet strip, the width of the electrode sheet strip being W1 and the length being L1;

[0050] S320, taking the cut electrode sheet strip in S310 and pasting double-sided adhesive on the back of the electrode sheet, wherein the size of the double-sided adhesive is not greater than the size of the electrode sheet strip;

[0051] S330, taking a hard bottom plate with a length of L2 and a width of W2, and L2>0.5*L1 and W2≥W1, folding the electrode sheet in S320 in the middle to make the back of the electrode sheet adhere to both sides of the bottom plate;

[0052] S340, another piece of hard base plate with a length of L3 and a width of W3, and W3≥W1, L3≥W1, and double-sided tape is pasted on the bottom of the above-mentioned base plate, the size of the double-sided tape is a square, the side length size is consistent with the width of the base plate;

[0053] S350, the middle bending part of the pole piece in S330 is adhered to the double-sided tape of the base plate in S340, the head of the base plate is clamped in the lower fixed port of the tensile machine, the base plate is fixed in the upper fixed port of the tensile machine, and the tensile machine is pulled upward to perform peel strength detection.

[0054] It should be noted that the width and length of the to-be-detected pole piece in step S310 have the following characteristics: the layer width ≤ the aluminum foil current collector ≤ the toughness layer; the material of the hard base plate in steps S320 and S340 includes but is not limited to any one of stainless steel sheet, glass plate and plastic plate; the direction of the tensile machine in step S350 is parallel to the length direction of the pole piece and the base plate.

[0055] Figure 4 is a schematic diagram of the structure of the pole piece of Example 1 shown by an exemplary embodiment of the present application; Figure 5 is a schematic diagram of the peel test of Example 1 shown by an exemplary embodiment of the present application; Figure 6 is a load-travel peel curve of Example 1 shown by an exemplary embodiment of the present application.

[0056] In a specific embodiment 1 of the present application, first, the positive electrode slurry is coated on the aluminum foil current collector by transfer coating to form a single-sided positive electrode piece with an active layer area density of 23 mg / cm2, and the proportion of the active layer is ternary material: SP: CNT: PVDF = 97: 0.5: 1: 1.5, wherein the thickness of the aluminum foil is 9 μm; then the single-sided positive electrode piece coated as above is cut into a single piece of 50 mm*100 mm, and double-sided tape is pasted on the back; then a carbon fiber cloth with the same size as the above single piece of electrode piece is taken, and the above electrode piece is pasted together through the back double-sided tape to form a composite electrode piece, wherein the thickness of the carbon fiber cloth is 100 μm; finally, the composite electrode piece is taken, and the active layer is compacted to a density of about 3.5 g / cm3 by rolling process to obtain a to-be-detected positive electrode piece 400 as shown in Figure 4 The uppermost layer of the pole piece is the active layer 401, the middle layer is the aluminum foil current collector 402, and the lowermost layer is the carbon fiber cloth 403.

[0057] In the specific test process of Embodiment 1, first, the aforementioned to-be-tested positive electrode sheet is made into an electrode sheet strip: composed of carbon fiber cloth 403, aluminum foil 402, and positive electrode material layer (active material layer) 401, with a width of 25 mm and a length of 100 mm; then, the electrode sheet strip 400 is taken, and the back of the electrode sheet strip 400 is pasted with double-sided tape, with a width of 25 mm and a length of 80 mm; secondly, a ferrous plate 502 is taken as a first bottom plate, with a thickness of 2 mm, a length of 100 mm, and a width of 25 mm, and the pasted electrode sheet 400 is folded in half, with the back of the electrode sheet 400 pasted on both sides of the ferrous bottom plate 502; then another piece of second bottom plate 503 with the same size as the first bottom plate is taken, and double-sided tape is pasted at the bottom of the first bottom plate 503. The double-sided tape is square with a side length of 25 mm; finally, the middle bending part of the folded electrode sheet 400 is adhered to the first bottom plate 502, and the head of the first bottom plate 502 is clamped in the lower fixed port of the tensile testing machine 501, and the second bottom plate 502 is fixed on the upper fixed port of the tensile testing machine 504. The tensile testing machine is pulled upward to test the peeling strength, and finally the peeling test state as shown in Figure 5 is formed. The pulling force of the tensile testing machine is continuously detected, and the peeling curve as shown in Figure 6 is obtained based on the obtained pulling force data.

[0058] Figure 7 is a schematic diagram of the structure of the control group 1 electrode sheet according to an example embodiment of the present application; Figure 8 is a schematic diagram of the peeling test of the control group 1 according to an example embodiment of the present application; Figure 9 is a load-travel peeling curve of the control group 1 according to an example embodiment of the present application.

[0059] In addition, in the control group 1 of the present application, the positive electrode slurry is first coated on the aluminum foil current collector by transfer coating to form a single-sided positive electrode sheet with an active material layer area density of 23 mg / cm2, and the active material layer ratio is ternary material: SP: CNT: PVDF = 97: 0.5: 1: 1.5; the aluminum foil thickness is 9 μm; then the single-sided positive electrode sheet after coating is cut into a single electrode sheet with a size of 50 mm*100 mm; finally, the single electrode sheet is subjected to a rolling process to realize a material layer compaction density of about 3.5 g / cm 3 , and a to-be-tested positive electrode sheet is obtained, as shown in Figure 7 .

[0060] In the specific testing process of control group 1, firstly, the aforementioned traditional positive electrode sheet was made into an electrode strip: composed of aluminum foil 702 and a positive electrode material layer 701, with a width of 25mm and a length of 100mm; secondly, an iron base plate 802, 100mm long and 25mm wide, was taken, and double-sided tape was pasted on the tail of the base plate 802. The double-sided tape was square, with a side length of 25mm; then, the aforementioned cut electrode strip 700 was taken, and the lower part of the material layer of the electrode strip 700 was pasted onto the iron base plate 802; finally, the first end of the iron base plate 802 was fixed to the lower fixing port 803 of the tensile testing machine, and the upper part of the electrode 700 was fixed to the upper fixing port 801 of the tensile testing machine. The tensile testing machine was used to pull upwards to perform a peel strength test, and the results were obtained. Figure 8 The peel test state is shown. The upward traction force of the tensile testing machine is continuously monitored, and the obtained traction force data is plotted as shown. Figure 9 The peeling curve shown.

[0061] Figure 10 These are photographs illustrating the state of the electrode sheets after peeling in Embodiment 1 and Control Group 1, as shown in an exemplary embodiment of this application. Figure 10 As shown, the left side of the image shows the electrode state of Example 1, and the right side shows the electrode state of the control group, where it is clearly visible that the control group electrode is broken. Based on... Figure 4 As shown in the load-stroke peel curve, within a stroke range of 2-5 mm, the peel force can be stabilized at around 5 N, and the electrode sheet does not break; further combined with Figure 9 As shown in the load-stroke peel curve, there is a significant drop in the middle of the curve, corresponding to the location where the electrode fracture occurred. This indicates that due to the influence of the cohesive force of the high-load material layer, the electrode fractured before the test was completed. At this time, the maximum peel force is 2.5N, which is much lower than the stable test result in Example 1, proving that the test result is inaccurate. The traditional test method is not suitable for high-load, high-pressure solid positive electrode sheets. Moreover, the positive electrode material layer peel strength detection method proposed in this application can effectively avoid the fracture of high-load, high-pressure solid positive electrode sheets during testing and accurately test the electrode material layer peel force.

[0062] Based on the experimental data of Example 1 and the control group, the following summary table of peel strength test results can be obtained. It can be seen that after adopting the test method of the present invention, internal stress can be effectively released, and high-load, high-pressure positive electrode sheets can be prevented from breaking during peel test. The test results can accurately reflect the peel strength of the material layer.

[0063] Table 1

[0064] Group Peeling strength (N) State Example 1 5 Normal Control group 1 2.5 Tab fracture

[0065] Therefore, the positive electrode sheet material layer peeling strength detection method proposed in the present application is aimed at the evaluation needs of the powder adhesion of high-load and high-compaction positive electrode sheets. The tension testing machine is used to test the peeling strength of the electrode sheet. Detailed steps, operation methods and related indicators are formulated, mainly including the following steps: sample selection, sample preparation, sample fixation, peeling test, data selection, sample characterization, etc. Through the test method, the peeling strength of high-load and high-compaction electrode sheets, especially the bending part of the wound electrode sheet, can be effectively evaluated, the accuracy and stability of the test data can be improved, and reference data can be provided for material selection, formula optimization, process improvement, etc. related to the adhesion strength of the electrode sheet.

[0066] Figure 11 is a block diagram of a positive electrode sheet material layer peeling strength detection device shown in an exemplary embodiment of the present application. The device can be applied to Figure 1 the implementation environment shown. The device can also be applied to other exemplary implementation environments and specifically configured in other devices. The present embodiment does not limit the implementation environment to which the device is applied.

[0067] As shown in Figure 11 , the exemplary positive electrode sheet material layer peeling strength detection device includes a material configuration module 1110, a structure to be detected generation module 1120, and a peeling strength detection module 1130.

[0068] The material configuration module 1110 is configured to prepare the positive electrode sheet to be detected, a first bottom plate, and a second bottom plate. The structure to be detected generation module 1120 is configured to bond the positive electrode sheet to be detected, the first bottom plate, and the second bottom plate to form a structure to be detected containing the positive electrode sheet. The peeling strength detection module 1130 is configured to fix the structure to be detected at both ends of a tensile testing machine and start the tensile testing machine to test the structure to be detected, so as to obtain the material layer peeling force of the positive electrode sheet to be detected, thereby realizing the detection of the material layer peeling strength of the positive electrode sheet to be detected.

[0069] In addition, the peeling strength detection module includes a tensile testing machine unit configured to detect the material layer peeling force of the positive electrode sheet to be detected, a sensor unit configured to send the material layer peeling force data of the tensile testing machine to a data processing unit, and the data processing unit configured to generate a load-travel peeling curve based on the obtained material layer peeling force data.

[0070] It should be noted that the positive electrode sheet material layer peeling strength detection device provided by the above embodiment and the positive electrode sheet material layer peeling strength detection method provided by the above embodiment belong to the same concept, wherein the specific manner in which each module and unit performs the operation has been described in detail in the method embodiment, and will not be described here. The positive electrode sheet material layer peeling strength detection device provided by the above embodiment can complete the above-described all or part of the functions by different functional modules according to the needs in the actual application, that is, the internal structure of the device is divided into different functional modules to complete the above-described all or part of the functions, and this is not limited here.

[0071] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical concept disclosed by the present application should be covered by the claims of the present application.

Claims

1. A method for detecting a positive electrode sheet layer peeling strength, characterized by, The method comprises: obtaining a to-be-tested positive plate, a first bottom plate, and a second bottom plate; bonding the to-be-tested positive plate, the first bottom plate, and the second bottom plate to form a to-be-tested structure containing the positive plate, comprising: cutting the to-be-tested positive plate based on a second preset size; determining a plate center of the to-be-tested positive plate, and dividing the to-be-tested positive plate into two ends along the plate center; bonding the first bottom plate to either side of the to-be-tested positive plate, the length of the first bottom plate being greater than half the length of the to-be-tested positive plate; folding the to-be-tested positive plate along the plate center so that the to-be-tested positive plate is bonded on both sides of the first bottom plate to form a first connecting body; and folding the first connecting body to form a bending part; and bonding one end of the second bottom plate to the bending part to form the to-be-tested structure; fixing the to-be-tested structure at two ends of a tensile tester; wherein one end of the first connecting body away from the bending part is fixed to one end of the tensile tester; and one end of the second bottom plate away from the bending part is fixed to the other end of the tensile tester; starting the tensile tester to perform a peeling light test on the to-be-tested structure to obtain a layer peeling force of the to-be-tested positive plate, so as to realize detection of a layer peeling strength of the to-be-tested positive plate.

2. The positive electrode sheet layer peel strength detection method according to claim 1, characterized by, Before obtaining the to-be-tested positive plate, the method further comprises: coating positive paste on an aluminum foil current collector to form a single-sided positive plate; cutting the single-sided positive plate based on a first preset size to obtain a to-be-processed positive plate; bonding a carbon fiber cloth to one side of the to-be-processed positive plate to form a composite positive plate; compacting the composite positive plate to a preset density threshold to obtain a to-be-tested positive plate.

3. The positive electrode sheet layer peel strength detection method according to claim 1, characterized by, Starting the tensile tester to perform a peeling light test on the to-be-tested structure to obtain a layer peeling force of the to-be-tested positive plate comprises: setting parameters of the tensile tester and starting the tensile tester; recording a tensile force value in a test process of the tensile tester to obtain the layer peeling force of the to-be-tested positive plate.

4. The positive electrode sheet layer peel strength detection method according to claim 2, characterized by, The coating process of coating positive paste on an aluminum foil current collector comprises any one of transfer type, doctor blade, and spraying type.

5. The positive electrode sheet layer peel strength detection method according to claim 1, characterized by, The to-be-tested positive plate, the first bottom plate, and the second bottom plate are bonded based on double-sided adhesive tape, the width of the double-sided adhesive tape is equal to the width of the to-be-tested positive plate, the width of the first bottom plate is greater than or equal to the width of the to-be-tested positive plate, and the width of the second bottom plate is greater than or equal to the width of the to-be-tested positive plate.

6. A device for testing the peel strength of a positive electrode sheet material layer, characterized in that, The device comprises: a material configuration module configured to prepare a to-be-tested positive plate, a first bottom plate, and a second bottom plate; The detection structure generation module is configured to bond the to-be-detected positive electrode sheet, the first bottom plate, and the second bottom plate to form a to-be-detected structure containing the positive electrode sheet, and includes: cutting the to-be-detected positive electrode sheet based on a second preset size; determining a sheet center of the to-be-detected positive electrode sheet, and dividing the to-be-detected positive electrode sheet into two ends along the sheet center; bonding the first bottom plate to either side of the to-be-detected positive electrode sheet, the length of the first bottom plate being greater than half the length of the to-be-detected positive electrode sheet; folding the to-be-detected positive electrode sheet along the sheet center, so that the to-be-detected positive electrode sheet is bonded on both sides of the first bottom plate to form the first connecting body; and folding the first connecting body to form a bending part; bonding one end of the second bottom plate to the bending part to form the to-be-detected structure. The peeling strength detection module is configured to fix the to-be-detected structure at two ends of a tensile tester, wherein one end of the first connecting body away from the bending part is fixed to one end of the tensile tester, one end of the second bottom plate away from the bending part is fixed to the other end of the tensile tester, and the tensile tester is started to perform a peeling strength test on the to-be-detected structure to obtain the layer peeling force of the to-be-detected positive electrode sheet, so as to detect the layer peeling strength of the to-be-detected positive electrode sheet.

7. The positive electrode sheet layer peel strength detection device according to claim 6, characterized by The peeling strength detection module includes: The tensile tester unit is configured to detect the layer peeling force of the to-be-detected positive electrode sheet. The sensor unit is configured to send the layer peeling force data of the tensile tester to the data processing unit. The data processing unit is configured to generate a load-displacement peeling curve based on the obtained layer peeling force data.

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