Diaphragm, battery cell, battery pack and electric equipment

Abstract

The utility model discloses a diaphragm, a battery cell, a battery pack and electric equipment, the diaphragm comprises a base film and a wave absorbing layer, the wave absorbing layer is arranged on the base film, and the wave absorbing layer is used for absorbing electromagnetic waves. According to the technical scheme, the wave absorbing layer is additionally arranged in the diaphragm, so that the absorption coefficient of the diaphragm on electromagnetic waves is improved, the diaphragm can present clear projection forming under the electromagnetic waves, the problem that the stacking state of the diaphragm in the battery cell cannot be detected is solved, the production cost of the battery cell is reduced, and the production efficiency of the battery cell is improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a diaphragm, a battery cell, a battery pack and an electrical device. Background Art

[0002] Optical detection is one of the commonly used methods for battery cell detection. Its main principle is to use the different absorption coefficients of electromagnetic waves of the objects to be detected, and the grayscale of the final imaging is also different, so as to obtain the position imaging of the positive electrode, negative electrode and diaphragm in the battery cell, and through the position imaging, judge the stacking of the positive electrode sheet, negative electrode sheet and diaphragm in the battery cell.

[0003] However, when the battery cells are inspected, the diaphragm absorbs electromagnetic waves weakly and the imaging is not obvious, so a full manual appearance inspection is required, which cannot be automated, and the internal diaphragm status cannot be detected manually, resulting in reduced production costs and efficiency. Utility Model Content

[0004] The purpose of this application is to provide a diaphragm, a battery cell, a battery pack and an electrical device, aiming to solve the problem in the related art that the diaphragm cannot be detected.

[0005] To achieve the purpose of the present application, in a first aspect, the present application provides a diaphragm, the diaphragm comprising:

[0006] basement membrane; and

[0007] The wave absorbing layer is arranged on the base film, and the wave absorbing layer is used to absorb electromagnetic waves.

[0008] In a possible implementation manner, the electromagnetic wave is X-ray.

[0009] In a possible implementation, the absorbing layer includes one of a barium oxide layer, a bismuth oxide layer, a barium sulfide layer, a barium sulfate layer, and a bismuth sulfide layer.

[0010] In a possible implementation manner, the absorbing layer covers a surface on one side of the base film in a thickness direction.

[0011] In a possible implementation manner, the diaphragm further includes an adhesive layer, and the adhesive layer is disposed on a side of the absorbing layer away from the base film; and / or the adhesive layer is disposed on a side of the base film away from the absorbing layer.

[0012] In a possible implementation manner, the diaphragm further includes a ceramic layer, and the ceramic layer is disposed on a side of the base film away from the absorbing layer; and / or the ceramic layer is disposed on a side of the base film away from the absorbing layer.

[0013] In a second aspect, the present application further proposes a battery cell, the battery cell comprising a positive electrode sheet, a negative electrode sheet and a separator, wherein the separator is arranged between the positive electrode sheet and the negative electrode sheet; the separator comprises:

[0014] basement membrane; and

[0015] The wave absorbing layer is arranged on the base film, and the wave absorbing layer is used to absorb electromagnetic waves.

[0016] In a possible implementation, the negative electrode sheet includes a negative electrode current collector, and an absorption coefficient of the absorbing layer to X-rays is different from an absorption coefficient of the negative electrode current collector to X-rays.

[0017] In a possible implementation manner, the absorption coefficient of the absorbing layer to X-rays is different from the absorption coefficient of the negative electrode current collector to X-rays.

[0018] In a possible implementation manner, the absorption coefficient of the wave absorbing layer to X-rays is smaller than the absorption coefficient of the negative electrode current collector to X-rays.

[0019] In a possible implementation, the grayscale value of the negative electrode current collector when imaged under X-rays is B, the grayscale value of the wave absorbing layer when imaged under X-rays is C, and CB≥20.

[0020] In a possible implementation, the positive electrode sheet includes:

[0021] Positive electrode current collector;

[0022] A protective layer is arranged on the positive electrode current collector and around the outer edge of the dressing layer. The absorption coefficient of the protective layer to electromagnetic waves is different from the absorption coefficient of the dressing layer to electromagnetic waves.

[0023] In a possible implementation manner, an absorption coefficient of the dressing layer to X-rays is different from an absorption coefficient of the protective layer to X-rays.

[0024] In a possible implementation, the X-ray absorption coefficient of the dressing layer is greater than the X-ray absorption coefficient of the protective layer.

[0025] In a possible implementation, the grayscale value of the dressing layer when imaged under X-rays is M, the grayscale value of the protective layer when imaged under X-rays is N, and NM≥20.

[0026] In a possible implementation manner, the absorption coefficient of the dressing layer to X-rays is smaller than the absorption coefficient of the protective layer to X-rays.

[0027] In a possible implementation, the grayscale value of the dressing layer when imaged under X-rays is M, the grayscale value of the protective layer when imaged under X-rays is N', and M-N'≥20.

[0028] In a possible implementation manner, the protective layer includes one of a barium oxide layer, a bismuth oxide layer, a barium sulfide layer, a barium sulfate layer, and a bismuth sulfide layer.

[0029] In a possible implementation manner, the protective layer includes one of a plastic layer and a rubber layer.

[0030] In a possible implementation, the dressing layer includes one of a lithium nickel cobalt manganese layer and a lithium iron phosphate layer.

[0031] In a third aspect, the present application further proposes a battery pack, the battery pack comprising a battery cell, the battery cell comprising a positive electrode sheet, a negative electrode sheet and a separator, the separator being arranged between the positive electrode sheet and the negative electrode sheet; the separator comprising:

[0032] basement membrane; and

[0033] The wave absorbing layer is arranged on the base film, and the wave absorbing layer is used to absorb electromagnetic waves.

[0034] In a fourth aspect, the present application further proposes an electrical device, the electrical device comprising a battery pack, the battery pack comprising a battery cell, the battery cell comprising a positive electrode sheet, a negative electrode sheet and a separator, the separator being arranged between the positive electrode sheet and the negative electrode sheet; the separator comprising:

[0035] basement membrane; and

[0036] The wave absorbing layer is arranged on the base film, and the wave absorbing layer is used to absorb electromagnetic waves.

[0037] The technical solution of the present application increases the absorption coefficient of the diaphragm for electromagnetic waves by adding an absorbing layer inside the diaphragm, so that the diaphragm can present a clear projection shape under electromagnetic waves, thereby solving the problem that the stacking state of the diaphragm in the battery cell cannot be detected, reducing the production cost of the battery cell and improving the production efficiency of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 A schematic diagram of the structure of the battery cell provided in this application;

[0040] Figure 2 The instantaneous state diagram of each mechanism of the electromagnetic wave detection equipment when the electromagnetic wave detection equipment detects the edge of the battery cell;

[0041] Figure 3 for Figure 1 a cross-sectional view of the diaphragm;

[0042] Figure 4 for Figure 1 A schematic structural diagram of another embodiment of the middle diaphragm;

[0043] Figure 5 for Figure 1 A cross-sectional view of a battery cell in one embodiment;

[0044] Figure 6 for Figure 1 Cross-sectional view of the positive electrode;

[0045] Figure 7 for Figure 1 A schematic diagram of the structure of the positive electrode in one embodiment;

[0046] Figure 8 for Figure 1 A schematic diagram of the structure of the positive electrode sheet in another embodiment;

[0047] Fig. 9 It is a projection view of the relevant technology under X-ray;

[0048] Fig.10 The projection under X-ray when plastic is used as the protective layer;

[0049] Fig.11 X-ray projection when bismuth oxide is used as the protective layer.

[0050] Description of reference numerals:

[0051] 1000 electromagnetic wave detection equipment;

[0052] 1 rack, 2 fixed platform, 3 detection light source assembly, 4 receiver;

[0053] 5 battery cells, 51 positive electrode sheet, 511 positive electrode current collector, 512 dressing layer, 513 protective layer, 52 separator, 521 ceramic layer, 522 base film, 523 absorbing layer, 524 adhesive layer, 53 negative electrode sheet, 531 negative electrode current collector. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0055] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there can be a central component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there can be a central component at the same time.

[0056] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in this application and in the specification are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this application includes any and all combinations of one or more of the related listed items.

[0057] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0058] The present application proposes an electrical device, which may be a vehicle, a ship, or an aircraft, and the present application does not limit this. For example, taking a vehicle as an example, when the electrical device is a vehicle, the vehicle may be an electric vehicle, a fuel vehicle, or a hybrid vehicle, and the present application does not limit this.

[0059] The vehicle includes a vehicle body, electronic devices and a battery pack. The vehicle body is used as the supporting body of the vehicle to provide support for various parts of the vehicle. The electronic device is arranged on the vehicle body, and the electronic device can be a dashboard, a motor controller, or a window lifting mechanism, which is not limited in this application.

[0060] The battery pack is stored in the battery compartment of the vehicle body, and the battery pack is electrically connected to the electronic devices. The battery pack is used to store and provide power when needed to maintain the normal use of electronic devices. The battery pack includes a case, battery cells, and a battery management system (BMS). The case serves as the supporting body of the battery pack and is used to provide support and connection for the various parts of the battery pack. The battery cells are contained in the case, and the battery cells serve as the energy storage unit of the battery pack, which is used to store and provide power to electronic devices when needed. The battery management system is electrically connected to the battery cells to monitor the current, temperature, and voltage of the battery cells.

[0061] Please refer to Figure 1 The battery cell 5 includes a positive electrode sheet 51, a negative electrode sheet 53 and a diaphragm 52. It can be understood that in other possible implementations of the present application, the battery cell 5 should also include a shell, which serves as a supporting body of the battery cell 5 and is used to support and connect the various parts of the battery cell 5. The shell is filled with an electrolyte, and the positive electrode sheet 51, the negative electrode sheet 53 and the diaphragm 52 are accommodated in the shell. The positive electrode sheet 51 and the negative electrode sheet 53 can react with the electrolyte to form an electric current. The diaphragm 52 is arranged between the positive electrode sheet 51 and the negative electrode sheet 53. The diaphragm 52 is used to physically isolate the positive electrode sheet 51 and the negative electrode sheet 53, prevent the electron conduction of the positive electrode sheet 51 and the negative electrode sheet 53, and avoid a short circuit in the battery cell 5; the diaphragm 52 also has an ion channel to allow ions in the electrolyte to pass through.

[0062] After the battery cells 5 are stacked and formed, their stacking conditions will be inspected. Optical inspection is one of the commonly used means for inspecting the battery cells 5. Its main principle is to use the different absorption coefficients of electromagnetic waves of the objects to be inspected, and the grayscale of the final imaging is also different, so as to obtain the imaging positions of the positive electrode, negative electrode and diaphragm in the battery cell 5, and judge the stacking conditions of the positive electrode sheet 51, negative electrode sheet 53 and diaphragm 52 in the battery cell 5 by the positions.

[0063] Specifically, please refer to Figure 2 The electromagnetic wave detection device 1000 includes a frame 1, a battery cell 5 fixing platform 2, a detection light source assembly 3 and a receiver 4. The frame 1 is used to provide support for the battery cell 5 fixing platform 2, the detection light source assembly 3 and the receiver 4; the battery cell 5 fixing platform 2 is used to fix the battery cell 5, and the fixing angle of the battery cell 5 can be adjusted according to the preset instructions. The detection light source assembly 3 is used to project the detection light to the battery cell 5 according to the preset instructions. The receiver 4 is used to receive the detection light projected by the detection light source.

[0064] In specific practice, after the battery cell 5 is placed on the fixed platform 2, the detection light source assembly 3 and the fixed platform 2 can be adjusted so that the electromagnetic wave rays in the detection light and shadow assembly can be irradiated on the battery cell 5 according to the preset angle and position. Figure 2 For example, Figure 2 This is a diagram of the instantaneous state of the electromagnetic wave detection device 1000 when detecting the uniformity of the edges of the battery cell 5. In this state, the electromagnetic wave irradiates the corners of the battery cell 5 at an incident angle of 45°. The electromagnetic wave can be an X-ray, or other rays that can be used for imaging detection, and this application does not limit this. Considering that X-rays have strong penetrability and low damage, in one embodiment of the present application, the electromagnetic wave uses X-rays, so as to improve the imaging quality of the electromagnetic wave detection device 1000 while reducing the damage to the object caused by the electromagnetic wave detection device 1000.

[0065] Since the positive electrode sheet 51, the negative electrode sheet 53 and the diaphragm 52 have different absorption coefficients for X-rays, the intensity of the X-rays that pass through the positive electrode sheet 51, the negative electrode sheet 53 and the diaphragm 52 and reach the receiver 4 is also different. Generally speaking, the greater the absorption coefficient of the object for the battery pack, the greater the amount of X-rays absorbed by the object. The intensity of the X-rays of the detection light source assembly 3 that pass through the object and reach the receiver 4 is smaller.

[0066] The terminal of the electromagnetic wave detection device 1000 will generate the grayscale value of the object according to the intensity of the X-rays reaching the receiver 4. The grayscale value of the object is between 0 and 256, where 0 represents black and 256 represents white. The larger the X-ray absorption coefficient of the object, the fewer X-rays the receiver 4 receives, the larger the grayscale value generated by the terminal, and the whiter the object image. Conversely, the smaller the X-ray absorption coefficient of the object, the more X-rays the receiver 4 receives, the smaller the grayscale value generated by the terminal, and the darker the object image. According to the grayscale imaging of the positive electrode sheet 51, the negative electrode sheet 53 and the diaphragm 52 at the terminal, the position of the positive electrode sheet 51, the negative electrode sheet 53 and the diaphragm 52 at the edge of the battery cell 5 can be determined, and then the alignment of the positive electrode sheet 51, the negative electrode sheet 53 and the diaphragm 52 at the corners of the battery cell 5 can be determined.

[0067] However, in the related art, when the battery cell 5 is inspected, the diaphragm 52 absorbs X-rays weakly and the imaging is not obvious, so a full appearance inspection is required manually, which cannot be automated, and the internal state of the diaphragm 52 cannot be detected manually, resulting in reduced production costs and production efficiency.

[0068] Please refer to Figure 3 To solve the above problems, in the present application, the diaphragm 52 includes a base film 522 and an absorbing layer 523. The base film 522 serves as a carrier of the diaphragm 52 and is used to support other structural layers of the diaphragm 52. At the same time, an ion channel is formed on the base film 522 to allow positive and negative ions in the electrolyte to pass through. The material of the base film 522 can be polyethylene or polyolefin, and the present invention does not limit this.

[0069] The wave absorbing layer 523 is disposed on the base film 522, and the wave absorbing layer is used to absorb X-rays. The wave absorbing layer 523 can be a barium oxide layer, a bismuth oxide layer, a barium sulfide layer, a barium sulfate layer, or a bismuth sulfide layer. The technical solution of the present application increases the absorption coefficient of the diaphragm 52 for X-rays by adding the wave absorbing layer 523 in the diaphragm 52, so that the diaphragm 52 can present a clear projection shape under X-rays, thereby solving the problem that the stacked state of the diaphragm 52 in the battery cell 5 cannot be detected, reducing the production cost of the battery cell 5, and improving the production efficiency of the battery cell 5.

[0070] There are many ways to set the absorbing layer 523 and the base film 522. In one embodiment of the present application, the absorbing layer 523 covers the surface of one side of the base film 522 in the thickness direction. In this way, the process steps of forming the absorbing layer 523 are reduced without affecting the basic function of the diaphragm 52, thereby reducing the production cost of the diaphragm 52 and improving the production efficiency of the diaphragm 52.

[0071] Please refer to Figure 4 In other embodiments of the present application, the absorbing layer 523 may also be arranged around the outer edge of one side surface in the thickness direction of the base film 522. In this way, the material of the absorbing layer 523 is saved, the weight of the diaphragm 52 is reduced, the manufacturing cost of the diaphragm 52 is reduced, and the weight of the formed battery cell 5 is reduced.

[0072] Generally speaking, in order to ensure that the separator 52 completely insulates the positive electrode sheet 51 and the negative electrode sheet 53, the four edges of the base film 522 of the separator 52 usually need to protrude outside the positive electrode sheet 51 and the negative electrode sheet 53. Figure 5 In one embodiment of the present application, the absorbing layer 523 is arranged around the outer edge of the base film 522, and the width of the absorbing layer 523 is A, 0.2mm≤A≤2mm. Under this size restriction, it can be ensured that the absorbing layer 523 can be located exactly at the part of the base film 522 protruding from the positive electrode sheet 51 and the negative electrode sheet 53. In this way, the diaphragm 52 can be identified while reducing the influence of the absorbing layer 523 on the ion mobility, thereby reducing the influence of the absorbing layer 523 on the performance of the battery cell 5.

[0073] The diaphragm 52 further includes an adhesive layer 524, which can be disposed on the side of the absorbing layer 523 away from the base film 522, so that the diaphragm 52 can be connected to the positive electrode sheet 51. The adhesive layer 524 can also be disposed on the side of the base film 522 away from the absorbing layer 523, so that the diaphragm 52 can be connected to the negative electrode sheet 53. The material of the adhesive layer 524 can be fiber or resin, and the utility model does not limit this.

[0074] The diaphragm 52 further includes a ceramic layer 521, which is used to support the diaphragm 52. The ceramic layer 521 can be disposed on the side of the base film 522 away from the absorbing layer 523, or on the side of the absorbing layer 523 away from the base film 522, which is not limited in the present application.

[0075] The diaphragm 52 is formed by the following steps:

[0076] S1, providing a polyolefin film as a base film 522;

[0077] S2. Coating a layer of barium oxide, bismuth oxide, barium sulfide, or bismuth sulfide on the polyolefin film.

[0078] S3 , coating a resin adhesive on one side of the second metal oxide or the second metal sulfide to form an adhesive layer 524 .

[0079] S4. Silicon oxide, aluminum oxide, boehmite, etc. are coated on the other side of the polyolefin film to form a ceramic layer 521.

[0080] Please refer to Figure 1 The negative electrode sheet 53 of the battery cell 5 serves as the energy storage part of the battery cell 5 . The negative electrode sheet 53 includes a negative electrode current collector 531 . The negative electrode current collector 531 is made of copper foil. The negative electrode current collector 531 serves as the main body of the negative electrode sheet 53 and is used to provide support for other structures of the negative electrode sheet 53 .

[0081] In one embodiment of the present application, the absorption coefficient of the absorbing layer 523 to X-rays is set to be different from the absorption coefficient of the negative electrode current collector 531 to X-rays. In this way, the negative electrode current collector 531 and the separator 52 can form a clearer boundary line in the projection imaging of the X-ray, so that the inspector can easily identify the position of the negative electrode sheet 53 and the separator, thereby improving the inspection efficiency of the battery cell 5.

[0082] The absorption coefficient of the wave absorbing layer 523 to X-rays may be greater than the absorption coefficient of the negative electrode current collector 531 to X-rays, or may be less than the absorption coefficient of the negative electrode current collector 531 to X-rays. This application does not impose any restrictions on this. In order to enable the diaphragm 52 and the negative electrode sheet 53 to have sufficient recognition under the projection of X-rays, in one embodiment of the present application, when the absorption coefficient of the wave absorbing layer 523 to X-rays is less than the absorption coefficient of the negative electrode current collector 531 to X-rays, the grayscale value of the negative electrode current collector 531 imaged under X-rays is B, and the grayscale value of the wave absorbing layer 523 imaged under X-rays is C, and CB≥20. When the absorption coefficient of the wave absorbing layer 523 to X-rays is greater than the absorption coefficient of the negative electrode current collector 531 to X-rays, the grayscale value of the negative electrode current collector 531 imaged under X-rays is B', and the grayscale value of the wave absorbing layer 523 imaged under X-rays is C', and B'-C'≥20. Under the limitation of the grayscale difference, a relatively clear boundary line can be formed between the negative electrode sheet 53 and the separator 52 , thereby facilitating the inspector to identify the positions of the negative electrode sheet 53 and the separator, thereby improving the inspection efficiency of the battery cell 5 .

[0083] The positive electrode sheet 51 of the battery cell 5 is used to release energy. During the discharge process of the battery cell 5 , the active material of the positive electrode sheet 51 and the active material of the negative electrode sheet 53 respectively undergo chemical reactions, thereby releasing electrons.

[0084] Please refer to Figures 6 to 8The positive electrode sheet 51 includes a positive electrode current collector 511, a protective layer 513 and a dressing layer 512. The material of the positive electrode current collector 511 is aluminum foil. The dressing layer 512 is arranged on the positive electrode current collector 511. The dressing layer 512 can be a lithium nickel cobalt manganese layer or a lithium iron phosphate layer. This application does not limit this. The dressing layer 512 is used to react with the electrolyte in the battery to generate electrical energy. The protective layer 513 is arranged on the positive electrode current collector 511 and is arranged around the outer edge of the dressing layer 512. The protective layer 513 can be as follows Figure 7 As shown, around one side of the dressing layer 512, it can also be as shown in Figure 8 As shown, the protective layer 513 surrounds the dressing layer 512, which is not limited in the present application. The protective layer 513 is insulated to prevent the dressing layer 512 from contacting the negative electrode current collector 531, thereby protecting the battery safety.

[0085] Please refer to Fig. 9 In the related art, under the projection of X-rays, the dressing layer 512 and the protective layer 513 of the positive electrode sheet 51 present a gradually fading image. This phenomenon is mainly because the protective layer 513 is made of aluminum oxide. Aluminum oxide and the lithium nickel cobalt manganese oxide of the dressing layer 512 of the positive electrode sheet 51 have similar absorption capabilities for X-rays, so the protective layer 513 and the dressing layer 512 cannot form a clear dividing line under the projection of X-rays, and the vertex of the dressing layer 512 cannot be determined.

[0086] To solve the above problem, in one embodiment of the present application, the absorption coefficient of the dressing layer 512 to electromagnetic waves is set to be different from the absorption coefficient of the protective layer 513 to electromagnetic waves. In this way, the protective layer 513 and the dressing layer 512 can produce a clear grayscale difference under the projection of the electromagnetic wave, so that the detector can easily determine the boundary between the dressing layer 512 and the protective layer 513, and determine the vertex position of the dressing layer 512 through the boundary, thereby improving the detection accuracy of the battery cell 5.

[0087] Continuing with the example of X-rays, in order to form a clear boundary between the protective layer 513 and the dressing layer 512, the absorption coefficient of the protective layer 513 for X-rays may be greater than the absorption coefficient of the dressing layer 512 for X-rays, or may be less than the absorption coefficient of the dressing layer 512 for X-rays, and the present application does not impose any restrictions on this. In one possible implementation of the present application, the protective layer 513 includes one of a plastic layer or a rubber layer, and the absorption coefficient of plastic or resin for X-rays is much smaller than the absorption coefficient of lithium nickel cobalt manganese oxide for X-rays. Under this material selection, the absorption coefficient of the protective layer 513 for X-rays is smaller than the absorption coefficient of the dressing layer 512 for X-rays, and the grayscale value of the dressing layer 512 imaged under X-rays is M, and the grayscale value of the protective layer 513 imaged under X-rays is N, and NM ≥ 20. For details, please refer to Fig.10 , Fig.10 The projection of the protective layer 513 when it is made of plastic under X-rays, wherein, since the absorption capacity of plastic for X-rays is much smaller than that of lithium nickel cobalt manganese oxide, the gray scale of the protective layer 513 made of plastic under X-ray projection is much larger than the gray scale of the dressing layer 512 made of lithium nickel cobalt manganese oxide. In this way, a clear visible boundary is formed between the protective layer 513 and the dressing layer 512, thereby improving the detection accuracy of the battery cell 5.

[0088] In other possible implementations of the present application, the protective layer 513 may also be one of a barium oxide layer, a bismuth oxide layer, a barium sulfide layer, a barium sulfate layer, and a bismuth sulfide layer. Under this material selection, the absorption coefficient of the protective layer 513 for X-rays is greater than the absorption coefficient of the dressing layer 512 for X-rays, the gray value of the dressing layer 512 under X-ray imaging is M, and the gray value of the protective layer 513 under X-ray imaging is N', M-N'≥20. For details, please refer to Fig.11 , Fig.11 The projection of the protective layer 513 under X-rays when using bismuth oxide, wherein, since bismuth oxide has a stronger absorption capacity for X-rays than lithium nickel cobalt manganese oxide, the grayscale of the protective layer 513 using bismuth oxide under projection is much smaller than the grayscale of the dressing layer 512 using lithium nickel cobalt manganese oxide. In this way, a clear visible boundary is formed between the protective layer 513 and the dressing layer 512. In this way, a clear visible boundary is formed between the protective layer 513 and the dressing layer 512, and the detection accuracy of the battery cell 5 is improved.

[0089] In the description of the embodiments of the present application, it should be noted that the orientation or positional relationship of terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside" and "outside" are based on the orientation or positional relationship described in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0090] What is disclosed above is only a preferred embodiment of the present application, and it certainly cannot be used to limit the scope of rights of the present application. Ordinary technicians in this field can understand that all or part of the processes of implementing the above embodiment and equivalent changes made according to the claims of the present application are still within the scope covered by the present application.

Claims

1. A diaphragm, applied to a battery cell, characterized in that: The diaphragm comprises: basement membrane; and A wave absorbing layer, the wave absorbing layer is arranged on the base film, and the wave absorbing layer is used to absorb electromagnetic waves; The absorbing layer covers a surface on one side of the base film in a thickness direction.

2. The diaphragm according to claim 1, characterized in that The electromagnetic waves are X-rays.

3. The diaphragm according to claim 1, characterized in that The wave absorbing layer includes one of a barium oxide layer, a bismuth oxide layer, a barium sulfide layer, a barium sulfate layer, and a bismuth sulfide layer.

4. The diaphragm according to claim 1, characterized in that The wave absorbing layer is arranged around the outer edge of one side surface of the base film in the thickness direction.

5. The diaphragm according to claim 4, characterized in that The width of the wave absorbing layer is A, 0.2 mm≤A≤2 mm.

6. The diaphragm according to any one of claims 1 to 5, characterized in that: The diaphragm further comprises an adhesive layer, and the adhesive layer is arranged on a side of the absorbing layer away from the base film; and / or the adhesive layer is arranged on a side of the base film away from the absorbing layer.

7. The diaphragm according to any one of claims 1 to 5, characterized in that: The diaphragm further comprises a ceramic layer, wherein the ceramic layer is arranged on a side of the base film away from the wave absorbing layer; and / or the ceramic layer is arranged on a side of the wave absorbing layer away from the base film.

8. A battery cell, characterized in that: The invention comprises a positive electrode sheet, a negative electrode sheet and a separator as claimed in any one of claims 1 to 7, wherein the separator is arranged between the positive electrode sheet and the negative electrode sheet.

9. The battery cell according to claim 8, characterized in that: The negative electrode sheet includes a negative electrode current collector, and the absorption coefficient of the absorbing layer to X-rays is different from the absorption coefficient of the negative electrode current collector to X-rays.

10. The battery cell according to claim 9, characterized in that: The absorption coefficient of the wave absorbing layer to X-rays is smaller than the absorption coefficient of the negative electrode current collector to X-rays.

11. The battery cell according to any one of claims 9 or 10, characterized in that: The grayscale value of the negative electrode current collector when imaged under X-rays is B, the grayscale value of the wave absorbing layer when imaged under X-rays is C, and CB≥20.

12. The battery cell according to claim 8, characterized in that: The positive electrode sheet comprises: Positive electrode current collector; A dressing layer, the dressing layer being disposed on the positive electrode current collector; A protective layer is arranged on the positive electrode current collector and around the outer edge of the dressing layer. The absorption coefficient of the protective layer to electromagnetic waves is different from the absorption coefficient of the dressing layer to electromagnetic waves.

13. The battery cell according to claim 12, characterized in that: The absorption coefficient of the dressing layer to X-rays is different from the absorption coefficient of the protective layer to X-rays.

14. The battery cell according to claim 13, characterized in that: The X-ray absorption coefficient of the dressing layer is greater than the X-ray absorption coefficient of the protective layer.

15. The battery cell according to claim 14, characterized in that: The grayscale value of the dressing layer when imaged under X-rays is M, and the grayscale value of the protective layer when imaged under X-rays is N, where NM≥20.

16. The battery cell according to claim 13, characterized in that: The X-ray absorption coefficient of the dressing layer is smaller than the X-ray absorption coefficient of the protective layer.

17. The battery cell according to claim 16, characterized in that: The grayscale value of the dressing layer when imaged under X-rays is M, the grayscale value of the protective layer when imaged under X-rays is N', and M-N'≥20.

18. The battery cell according to claim 12, characterized in that: The protective layer includes one of a barium oxide layer, a bismuth oxide layer, a barium sulfide layer, a barium sulfate layer, and a bismuth sulfide layer.

19. The battery cell according to claim 12, characterized in that: The protective layer includes one of a plastic layer and a rubber layer.

20. The battery cell according to claim 12, characterized in that: The dressing layer includes one of a lithium nickel cobalt manganese layer and a lithium iron phosphate layer.

21. A battery pack, characterized in that: Comprising a battery cell as described in any one of claims 8 to 20.

22. An electrical equipment, characterized in that: Comprising the battery pack as claimed in claim 21.

Images