CN102620993A - Battery pole piece flexibility characterization method and flexibility testing device - Google Patents

Abstract

The invention discloses a method for characterizing the flexibility of a battery pole piece, which comprises the following steps: (1) cutting the battery pole piece into a rectangle of a certain size, and rolling it into a single-layer cylindrical surface; (3) During the deformation process, detect the shear stress at the left and right ends of the cylindrical pole piece and the corresponding displacement at the upper and lower ends, and obtain the shear stress-displacement curve (4) Analyzing and processing the shear stress-displacement curve to obtain the characterization of the flexibility of the battery pole piece. Compared with the prior art, the battery pole piece flexibility characterization method of the present invention can quickly and quantitatively test the flexibility of the battery pole piece, and the test accuracy is greatly improved. In addition, the invention also discloses a device for testing the flexibility of battery pole pieces.

Description

Characterization method and flexibility test device for battery pole piece flexibility

technical field

The invention relates to the field of testing the mechanical properties of diaphragms, and more specifically, the invention relates to a method for characterizing the flexibility of a battery pole piece and a related flexibility testing device.

Background technique

With the development of modern society and the enhancement of environmental awareness, more and more devices choose to use rechargeable secondary batteries as power sources, such as mobile phones, notebook computers, power tools, electric vehicles, etc. Application and development provide a broad space, but also put forward higher requirements for secondary batteries, hoping that they can have higher capacity, good safety and longer cycle life.

However, high capacity requires higher coating weight and compaction density of the battery pole piece, which makes the flexibility of the battery pole piece worse, especially the positive pole piece. During the winding process of the square cell pole piece, especially when the positive pole piece is bent, the extruding shear stress on both sides of the winding core and the pulling shear stress on the outside are the largest, which makes the diaphragm easy to occur on both sides of the winding. fracture; and when the cylindrical battery core is wound, the degree of wrinkling of the pole piece wound on the inner ring also has a great relationship with the flexibility of the pole piece. During the shaping process of the square cell with winding structure, the cell is subjected to external pressure, and the deformation and shear stress of the cell pole pieces at both ends of the winding are the largest, and it is easy to break. It can be seen that pole pieces with poor flexibility, on the one hand, affect the efficiency of the winding process, resulting in economic losses;

At present, there are mainly two methods to characterize the flexibility of the battery pole piece. One method is to wind the pole piece with reels of different diameters, and then distinguish the degree of wrinkling of the pole piece with the naked eye; the second method is to wrap the battery pole piece Stretch it after folding it in half and hold it up to the light to see if there are any cracks. These two methods rely on human subjective judgment to a large extent, and have limited accuracy. They cannot effectively distinguish pole pieces with small differences in flexibility, nor can they quantitatively characterize the flexibility of pole pieces.

In view of this, it is indeed necessary to develop a high-precision battery pole piece flexibility characterization method and flexibility testing device.

Contents of the invention

The purpose of the present invention is to provide a high-precision battery pole piece flexibility characterization method and a flexibility testing device, so as to quantitatively characterize the flexibility of the battery pole piece.

In order to achieve the purpose of the above invention, the present invention provides a method for characterizing the flexibility of a battery pole piece, which includes the following steps: (1) cutting the battery pole piece into a rectangle of a certain size, and rolling it into a single-layer cylindrical surface; (2) From the direction perpendicular to the cylindrical surface of the battery pole piece, apply pressure to the cylindrical surface at a uniform speed to cause a fixed elliptical deformation; (3) During the deformation process, detect the shear stress at the left and right ends of the cylindrical pole piece and the corresponding displacement at the upper and lower ends, Obtain the shear stress-displacement curve; (4) analyze and process the shear stress-displacement curve to obtain the characterization of the flexibility of the battery pole piece.

As an improvement of the battery pole piece flexibility characterization method of the present invention, the analysis and processing method adopted in the step (4) is: the shear stress corresponding to the left and right ends when the cylindrical surface of the battery pole piece undergoes fixed deformation Characterizes the flexibility of the pole piece.

As an improvement of the method for characterizing the flexibility of the battery pole piece of the present invention, the analysis and processing method adopted in the step (4) is: the flexibility of the pole piece is characterized by the average slope of the shear stress-displacement curve.

As an improvement to the method for characterizing the flexibility of the battery pole piece of the present invention, the rectangular pole piece cut out in the step (1) has a size of 30-40 mm in width and 100-110 mm in length.

As an improvement of the method for characterizing the flexibility of the battery pole piece of the present invention, in the step (2), pressure is applied to the cylindrical surface of the pole piece at a speed of less than 2mm/s.

In order to achieve the purpose of the above invention, the present invention also proposes a battery pole piece flexibility testing device, which includes a dynamic loading mechanism, a dynamic signal acquisition unit, a dynamic signal transmission unit, and a data processing unit. The dynamic loading mechanism includes a main frame, a low-speed Cylinder, parallel platen and sample platform. The low-speed cylinder and sample platform are fixed on the main frame. The pole piece to be tested is fixed on the sample platform. The pressure plate and the sample platform are vertically corresponding in space, the dynamic signal acquisition unit is mechanically connected with the dynamic loading mechanism, and the dynamic signal acquisition unit, the dynamic signal transmission unit and the data processing unit are sequentially connected through signals.

As an improvement of the battery pole piece flexibility testing device of the present invention, two raised rectangular positioning bars and two magnets parallel to the platform are arranged on the center line of the sample platform, and one is dedicated to fixing the battery pole piece. The fixing buckle is provided with two rectangular perforations, and the fixing buckle is positioned on the sample platform through a magnet.

As an improvement of the battery pole piece flexibility testing device of the present invention, the dynamic signal acquisition unit includes an optical fiber displacement sensor and a dynamic load sensor, and the optical fiber displacement sensor is arranged on the parallel platen to detect the displacement of the parallel platen in the vertical direction The dynamic load sensor is set under the sample platform to detect the shear stress on both ends of the cylindrical pole piece.

As an improvement of the battery pole piece flexibility testing device of the present invention, the dynamic signal transmission unit is an electromagnetic signal converter, which establishes electrical signal connections with the optical fiber displacement sensor, dynamic load sensor and data processing unit respectively, and can connect the optical fiber The electromagnetic signals collected by the displacement sensor and the dynamic load sensor are converted into signals that can be recognized and processed by the data processing unit and transmitted to the data processing unit. The data processing unit makes the displacement and shear stress signals received from the dynamic signal transmission unit into Shear stress-displacement curve.

As an improvement of the battery pole piece flexibility testing device of the present invention, the distance between the parallel platen in the dynamic loading mechanism and the sample platform after being pressed down to the bottom is 8-16 mm.

Compared with the prior art, the battery pole piece flexibility characterization method of the present invention can quickly and quantitatively test the flexibility of the battery pole piece, and the test accuracy is greatly improved.

Description of drawings

The method for characterizing the flexibility of the battery pole piece, the testing device and its beneficial technical effects of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

FIG. 1 is a schematic structural diagram of a battery pole sheet flexibility testing device of the present invention.

Fig. 2 is a schematic diagram of the sample platform structure of the battery pole piece flexibility testing device of the present invention.

Fig. 3 is a force analysis diagram of the battery pole piece before testing using the battery pole piece flexibility characterization method and testing device of the present invention.

Fig. 4 is a force analysis diagram of the battery pole piece when tested using the battery pole piece flexibility characterization method and testing device of the present invention.

Fig. 5 is a displacement-shear stress curve diagram of the influence of the compacted density on the flexibility of the positive electrode sheet measured by the present invention.

Detailed ways

The battery pole piece flexibility characterization method of the present invention rolls the battery pole piece into a single-layer cylindrical surface, then applies pressure to the cylindrical surface at a uniform speed to cause a fixed elliptical deformation, and reflects the force analysis of the entire deformation process. The flexibility of the battery pole piece under pressure after winding.

Please refer to FIG. 1 and FIG. 2 , in order to realize the above method, the present invention provides a battery pole piece flexibility testing device, which includes a dynamic loading mechanism, a dynamic signal acquisition unit, a dynamic signal transmission unit 30 and a data processing unit 40 . The dynamic loading mechanism is mechanically connected to the dynamic signal acquisition unit, and the dynamic signal acquisition unit, the dynamic signal transmission unit 30 and the data processing unit 40 are sequentially connected through signals.

The dynamic loading mechanism includes a main frame 12 , a low-speed cylinder 14 , a parallel platen 16 and a sample platform 18 . Wherein, the low-speed cylinder 14 is fixed on the top of the main frame 12, the parallel platen 16 is fixed on the bottom of the low-speed cylinder 14, the sample platform 18 is fixed on the bottom of the main frame 12 and is positioned under the parallel platen 16, the low-speed cylinder 14, the parallel platen 16 and The sample platforms 18 correspond vertically in space. The center line of the sample platform 18 is provided with two raised rectangular positioning brackets 180 and two magnets 182 parallel to the platform, and a fixed buckle 184 dedicated to fixing the cylindrical pole piece 60 is provided with two rectangular perforations , the fixing buckle 184 is positioned on the sample platform 18 through the magnet 182 . The top of the low-speed cylinder 14 is connected to the air gauge, and its action is controlled by a precision pressure regulating valve. The parallel platen 16 below it is used to load and apply pressure to the cylindrical pole piece 60 on the sample platform 18 .

The dynamic signal acquisition unit includes an optical fiber displacement sensor 22 and a dynamic load sensor 24 . The optical fiber displacement sensor 22 is arranged on the parallel platen 16 for detecting the displacement variation of the parallel platen 16 in the vertical direction. The dynamic load sensor 24 is arranged under the sample platform 18 for detecting the shear stress on both ends of the cylindrical pole piece 60 .

The dynamic signal transmission unit 30 is an electromagnetic signal converter, which establishes electrical signal connections with the optical fiber displacement sensor 22, the dynamic load sensor 24 and the data processing unit 40 respectively, so that the electromagnetic signals collected by the optical fiber displacement sensor 22 and the dynamic load sensor 24 It is converted into a signal that can be recognized and processed by the data processing unit 40 and sent to the data processing unit 40 .

The data processing unit 40 is a computer, and its data processing module can make the displacement and shear stress signals received from the dynamic signal transmission unit 30 into a shear stress-displacement curve.

The principle of the present invention will be described in detail below.

Please refer to FIG. 3 , before the cylindrical pole piece 60 is fixed on the sample platform 18 to start testing, the cylindrical pole piece 60 is only subjected to its own gravity mg and the support force N ₀ of the sample platform in the vertical direction. These two forces are balanced forces, that is, mg=N ₀ , at this time, the dynamic load sensor 24 under the sample platform 18 can feel the pressure F'=N ₀ =mg of the pole piece on the sample platform 18 . At the beginning of the test, by clearing the pressure collected by the dynamic load sensor 24 , the pressure increased by the cylindrical surface pole piece 60 on the sample platform 18 during the stress deformation process can be tested.

Please refer to Fig. 4, the cylindrical pole piece 60 is deformed into an ellipse under the vertical load applied by the parallel platen 16, and it is subjected to a pair of balancing forces in the vertical direction, that is, the downward load F and the upward supporting force N . Since the elliptical pole piece 60 is a symmetrical structure, the upper half of it is now taken for force analysis: as shown in Figure 4, the elliptical pole piece 60 is subjected to a vertical downward load F in the vertical direction, and at both ends of the ellipse major axis Then it is subjected to two vertical upward shear stresses f. In the deformation process, the pressure F' collected by the dynamic load sensor 24 below the sample platform 18 and its supporting force N to the pole piece are a pair of acting force and reaction force, F'=N=F=2f, so the sensor collects The obtained force F' can reflect the magnitude of the shear stress at both ends of the ellipse of the bent pole piece. Since the theoretical solution of the complex shear stress state does not exist, it is now assumed that the pole piece is a linear elastic body.

From the formula for the perimeter of an ellipse:

dl=(4du _x -2πdu')----(1);

According to Hook's law:

$\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; ES</span>}}{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}\mathrm{<span\; class="notranslate">\; \&Delta;l</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; k\&Delta;l</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$

According to the principle of virtual work:

Fdu'=k(ll ₀ )(4du _x -2πdu')----(3);

The relationship between pressure and displacement can be obtained from formulas (1) to (3):

F=12ku'----(4);

Among them, k=ES/l ₀ in the formula (4), E is the elastic modulus, which characterizes the ability of the material to resist elastic strain, the lower the value, the easier it is to undergo elastic deformation, indicating the better the flexibility; S is the pole piece 60 The cross-sectional area; l ₀ is the initial circumference length of the cylindrical pole piece 60. It can be seen that when the cross-sectional area and length of the pole piece 60 are fixed, the ratio of the pressure F to the displacement u' is directly proportional to the elastic modulus of the material, ie: F/u'˜E. Since F'=N=F=2f, therefore F'/u'～E, that is to say, when the cylindrical surface pole piece 60 undergoes a fixed deformation under the parallel platen 16 applying the load, the F collected by the dynamic load sensor 24 The 'value can reflect the flexibility of the pole piece: the larger the F', the greater the elastic modulus E of the material of the pole piece, the higher its ability to resist elastic strain, and the harder it is to undergo elastic deformation, that is, the higher the flexibility Therefore, F' can quantitatively characterize the shear stress f on both sides of the cylindrical pole piece when it is deformed.

Since the pole piece material is a complex material formed by compacting the powder and colloid on the surface with the foil as a support, it is similar to a reinforced concrete structure, and the elastic modulus E of the material is the same as the pole piece material (formula ), compaction density, coating weight, etc. Due to the change in the cross-sectional area S of the pole piece caused by the compaction density and coating weight of the pole piece relative to the change in the elastic modulus E of the pole piece is very small, it can be considered that the shear stress f of the pole piece is only related to the elastic modulus E , so that the degree of flexibility of pole pieces with different formulations, compacted densities, and coating weights can be quantitatively characterized.

The shear stress and strain of complex materials do not conform to a linear relationship under conditions such as loading rate, that is, E changes during continuous loading, and the faster E increases, the stronger the material's ability to resist elastic strain during loading , the less prone to elastic deformation, the worse its flexibility. Therefore, the flexibility of the pole piece can be judged by the change trend of the shear stress of the pole piece with the displacement during the loading process.

In order to ensure the accuracy of the measurement results, the main parameters related to the present invention will be analyzed and set below.

When using the battery pole piece flexibility testing device of the present invention to test the flexibility of the battery pole piece 60, there is an acceleration process of 5mm when the low-speed cylinder 14 starts, and the running speed after starting should be less than 2mm/s, preferably 0.5mm/s, which is It is to ensure that the moving speed of the parallel pressing plate 16 is less than 2mm/s, so as to prevent the test result from being affected by the high speed of the parallel pressing plate 16 and increase the shear stress of the pole piece. Please refer to Table 1 for the influence of the moving speed of the parallel platen 16 on the position stress test results.

Table 1. Data on the influence of the moving speed of the parallel platen on the position stress test results

The parallel platen 16 is fixed on the lower part of the low-speed cylinder 14, and the distance between it and the sample platform 18 after it is pressed down to the bottom can be realized by installing steel rings of different heights between the parallel platen 16 and the connecting rod of the low-speed cylinder 14, changing the height of the steel ring Different degrees of deformation of the cylindrical pole piece 60 can be achieved. Please refer to the impact data of the distance between the lowest point of the parallel platen 16 and the sample platform 18 shown in Table 2 on the test error. In order to ensure that the test error is less than 5%, the distance between the parallel platen 16 and the sample platform 18 after pressing down to the bottom should be 8 Within -16mm, the spacing used in subsequent embodiments is 13mm.

Table 2. Data on the influence of the distance between the parallel platen and the sample platform on the test error

Please refer to the battery pole piece dimensions and their corresponding shear stress test results shown in Table 3. For pole pieces of the same width, the longer the pole piece, the larger the diameter of the cylindrical surface it is wound into. When the cylindrical surfaces of different diameters are deformed by the force of the parallel platen 16 in the vertical direction, the deformation of the cylindrical surface with a large diameter is larger than that of the cylindrical surface with a small diameter, and its shear stress is also greater, such as a 30mm negative pole piece. , in the length range from 90mm to 110mm, the shear stress value increases with the length of the pole piece. However, as the length of the pole piece continues to increase, its wound cylindrical surface is more affected by its own gravity, and before being subjected to the vertical pressure of the parallel pressing plate 16, the wound cylindrical surface presents an ellipse. In this state, the shear stress experienced by the elliptical pole piece is zeroed during the test, resulting in the final measured shear stress value being lower than the true value of the final deformation, such as a pole piece with a width of 30mm, when the length is increased to 120mm , and the test results decrease instead. Therefore, it is necessary to ensure that the tested pole piece 60 is long enough to ensure that the test result is large enough, and to ensure that the tested pole piece 60 does not appear elliptical when it is wound to ensure the accuracy of the test. The length of the tested pole piece 60 must be specified. . According to the battery pole piece size and its corresponding shear stress test results shown in Table 3, the cutting size of the rectangular battery pole piece is 100-110 mm in length, which has accurate and stable test results. When the width of the pole piece is 30-50 mm, the buckle 184 with two holes can perfectly fix the winding pole piece.

Table 3. Dimensions of battery pole pieces and their corresponding shear stress test results

The following is an example of using the characterization method and testing device of the present invention to measure the flexibility of battery pole pieces.

In order to save materials, this embodiment uses battery pole pieces with a length of 100 mm and a width of 30 mm. The distance between the two positioning shanks 180 on the center line of the sample platform 18 is 20 mm, and the length, width and height of the two positioning shanks 180 are 20 mm, 3 mm, and 2 mm, respectively. Circular magnet 182 is positioned at the two ends of positioning Shan 180 and is embedded in sample table 18, and its upper surface is flush with sample platform 18; Platform 18 is a tangential cylindrical surface. Put the buckle 184 with two holes on the battery pole piece 182, and the two holes of the buckle 184 correspond to the two positioning brackets 180 on the sample stage 18, as shown in FIG. 2 . The magnets 182 at the two ends of the positioning bracket 180 can firmly hold the buckle 184, thereby fixing the battery pole piece 60 to be tested well.

After the sample is fixed, turn on the power of the dynamic loading mechanism and the displacement-force interface of the data processing unit 40 . Press the switch of the dynamic loading mechanism and click the start key of the data processing unit 40 at the same time, the low-speed cylinder 14 pushes the parallel platen 16 to move to the cylindrical pole piece 60 on the sample platform 18, and the optical fiber displacement sensor 22 and the dynamic load sensor 24 will collect real-time data respectively. The received signal is transmitted to the dynamic signal transmission unit 30 , and the dynamic signal transmission unit 30 converts the electromagnetic signal into a signal that can be recognized and processed by the data processing unit 40 and transmits it to the data processing unit 40 . The data processing unit 40 processes the signal and displays it graphically on its displacement-force interface, and finally forms a corresponding data file. The data file gives the displacement and shear stress collected every 0.003s, and draws the displacement-shear stress curve. The maximum shear stress in the deformation process is used as the basis for judging the flexibility of the pole piece: the greater the shear stress of the pole piece, the worse the flexibility , the pole piece is more likely to be brittle.

For the lithium battery pole piece, by testing the shear stress of the cylindrical surface pole piece 60 after a certain deformation, it is found that the shear stress of the positive pole piece is much larger than that of the negative pole piece, and the shear stress increases more obviously with the change of the pressure plate displacement, indicating that the positive pole piece The elastic modulus of the negative electrode sheet is larger than that of the negative electrode sheet, and its ability to resist elastic deformation is stronger, less prone to elastic deformation, and less flexible. This is also consistent with the fact that the positive electrode sheet is more likely to break than the negative electrode sheet during the bare cell winding and cell shaping process.

Please refer to Figure 5. For the positive electrode sheets with the same coating weight and formula, the measured results show that as the compaction density of the electrode sheet increases, the shear stress corresponding to the fixed deformation of the electrode sheet also increases, which shows that the compression The greater the solid density, the greater the elastic modulus E of the pole piece, the stronger its ability to resist elastic deformation, the harder it is to elastically deform, the worse the flexibility of the pole piece, and the easier it is to break. At the same time, it can also be seen from Figure 5 that during the entire process of forming an elliptical pole piece under load on the cylindrical surface, the shear stress also increases with the displacement of the pressure plate. The more obvious the stress increases, the more obvious the elastic modulus E increases during the loading process, the stronger its ability to resist elastic deformation, the harder it is to elastically deform, the worse the flexibility of the pole piece, and the more easy to break.

In summary, the present invention can quantitatively measure the magnitude of the shear stress corresponding to both ends of the pole piece when the cylindrical surface pole piece 60 of the battery is fixedly deformed. This force is positively correlated with the elastic modulus E of the pole piece 60, and the elastic modulus E is the ability to characterize the material’s ability to resist elastic deformation. The stronger the ability, the harder it is to undergo elastic deformation, the easier it is to break easily, and the worse the flexibility. From this result, the degree of flexibility of the pole piece can be judged. At the same time, the flexibility of the pole piece can also be judged according to the change trend of the shear stress with the displacement when the pole piece is deformed, that is, as the displacement of the parallel platen increases, the degree of increase of the shear stress of different pole pieces, that is, the elastic modulus E increases with the parallel platen displacement. The degree of increase in displacement, the more obvious the increase in E, the stronger the ability to resist elastic deformation, the harder it is to undergo elastic deformation, and the worse the flexibility. The test device of the invention has a good resolution of 0.1gf, and has good discrimination and reproducibility for the test results of the pole piece shear stress. The test device of the present invention has a simple structure, and is suitable for battery positive and negative pole pieces, other coating structures, and plastic membranes, and is especially suitable for testing the flexibility of battery pole pieces with winding structures, such as lithium-ion battery pole pieces, nickel The test of the flexibility of hydrogen battery pole pieces and nickel-cadmium battery pole pieces can be used to monitor the flexibility of different types of battery pole pieces, provide reference for automatic winding tension and shaping pressure adjustment, and can also be used for formula development, cold storage It provides a basis for the selection of pressure parameters and effectively prevents the brittle fracture of the winding of the pole piece.

According to the disclosure and teaching of the above specification, those skilled in the art to which the present invention pertains can also make appropriate changes and modifications to the above embodiment. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims (10)

1. A battery pole piece flexibility characterization method, is characterized in that, comprises the following steps: (1) Cut the battery pole piece into a rectangle of a certain size, and roll it into a single-layer cylindrical surface; (2) From a direction perpendicular to the cylindrical surface of the battery pole piece, apply pressure to the cylindrical surface at a uniform speed to cause a fixed elliptical deformation; (3) During the deformation process, the shear stress at the left and right ends of the cylindrical pole piece and the corresponding displacement at the upper and lower ends are detected to obtain a shear stress-displacement curve; (4) Analyze and process the shear stress-displacement curve to obtain the characterization of the flexibility of the battery pole piece. 2. The method for characterizing the flexibility of the battery pole piece according to claim 1, wherein the analysis and processing method adopted in the step (4) is: when the cylindrical surface of the battery pole piece is fixedly deformed, the left and right ends The corresponding shear stress characterizes the flexibility of the pole piece. 3. The method for characterizing the flexibility of the battery pole piece according to claim 1, wherein the analysis and processing method adopted in the step (4) is: characterize the pole piece with the average slope of the shear stress-displacement curve of flexibility. 4. The method for characterizing the flexibility of battery pole pieces according to any one of claims 1 to 3, wherein the dimensions of the rectangular pole pieces cut out in the step (1) are: width 30-40 mm, length 100-110mm. 5. The battery pole piece flexibility characterization method according to any one of claims 1 to 3, characterized in that, in the step (2), pressure is applied to the cylindrical surface of the pole piece at a speed of less than 2 mm/s of. 6. A battery pole piece flexibility testing device, characterized in that it includes a dynamic loading mechanism, a dynamic signal acquisition unit, a dynamic signal transmission unit and a data processing unit, and the dynamic loading mechanism includes a main frame, a low-speed cylinder, a parallel platen and a sample platform , the low-speed cylinder and the sample platform are fixed on the main frame, the pole piece to be tested is fixed on the sample platform, and the parallel platen is fixed on the low-speed cylinder to exert pressure on the pole piece to be tested. The low-speed cylinder, parallel platen and sample platform are spaced Vertical correspondence, the dynamic signal acquisition unit is mechanically connected to the dynamic loading mechanism, and the dynamic signal acquisition unit, the dynamic signal transmission unit, and the data processing unit are sequentially connected through signals. 7. The battery pole piece flexibility test device according to claim 6, characterized in that, two raised rectangular positioning bars and two magnets parallel to the platform are arranged on the center line of the sample platform, and one dedicated There are two rectangular perforations on the fixing buckle that fixes the battery pole piece, and the fixing buckle is positioned on the sample platform through a magnet. 8. The battery pole piece flexibility testing device according to claim 6, wherein the dynamic signal acquisition unit includes an optical fiber displacement sensor and a dynamic load sensor, and the optical fiber displacement sensor is arranged on the parallel platen for detecting the parallel platen For the displacement variation in the vertical direction, the dynamic load sensor is arranged under the sample platform to detect the shear stress on both ends of the cylindrical pole piece. 9. The battery pole piece flexibility testing device according to claim 8, wherein the dynamic signal transmission unit is an electromagnetic signal converter, which establishes electrical connections with the optical fiber displacement sensor, the dynamic load sensor and the data processing unit respectively. Signal connection, which can convert the electromagnetic signal collected by the optical fiber displacement sensor and dynamic load sensor into a signal that can be recognized and processed by the data processing unit and transmit it to the data processing unit. The data processing unit converts the displacement received from the dynamic signal transmission unit , The shear stress signal is made into a shear stress-displacement curve. 10 . The device for testing the flexibility of battery pole pieces according to claim 6 , wherein the distance between the parallel platens in the dynamic loading mechanism and the sample platform after being pressed down to the bottom is 8-16 mm. 11 .

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