Battery cell and battery

Abstract

The utility model discloses a battery cell and a battery, and belongs to the technical field of batteries. The battery cell comprises a roll core assembly and an adhesive film, and the elastic modulus of a first adhesive part in the adhesive film is greater than that of a second adhesive part. Therefore, after the adhesive film is wound on the roll core assembly, the first adhesive part with the larger elastic modulus can be wound on the first roll core part with the smaller size, and the second adhesive part with the smaller elastic modulus can be wound on the second roll core part with the larger size; in this way, it can be guaranteed that the second roll core part with the large size is tightly wound by the second bonding part with the small elastic modulus, meanwhile, it can be guaranteed that the first roll core part with the small size can be tightly wound by the first bonding part with the large elastic modulus, and therefore it is guaranteed that the whole roll core assembly can be tightly wound by the bonding film; therefore, the overall fitting degree of the positive pole piece and the negative pole piece in the roll core assembly is relatively good, and the phenomena of poor lithium embedding and lithium separation in the working process of the battery core are avoided.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery cell and battery. Background Technology

[0002] With the continuous development of battery technology, many electronic devices in daily life use lithium-ion cells to provide power. Currently, a lithium-ion cell mainly consists of a positive electrode, a negative electrode, a separator, an electrolyte, and a casing. The positive electrode, separator, and negative electrode, wound together, need to be placed into a casing containing the electrolyte to form a cell. After the positive electrode, separator, and negative electrode are wound, a final layer of adhesive tape is wrapped around them to secure them.

[0003] Currently, in the process of producing positive and negative electrode sheets using coating technology, due to equipment and process limitations, there is a thinning zone at the edge of the electrode sheet. The thickness of the thinning zone is less than the thickness of the normal coating zone. As a result, after the positive and negative electrode sheets, separator, and negative electrode sheets are wound together, the bonding between the edges of the positive and negative electrode sheets and the separator is poor. This increases the lithium ion transport path during the operation of the battery cell, making the battery cell more prone to poor lithium intercalation and lithium plating.

[0004] However, the current termination adhesive paper in the battery cell cannot improve the adhesion between the edges of the positive and negative electrodes and the separator, and therefore cannot effectively improve the lithium insertion failure and lithium plating phenomenon in the battery cell. Utility Model Content

[0005] This application provides a battery cell and a battery. It can solve the problem of poor adhesion between the edges of the positive and negative electrode sheets and the separator in existing technologies. The technical solution is as follows:

[0006] On one hand, a battery cell is provided, the battery cell comprising: a core assembly and an adhesive film;

[0007] The core assembly includes: a first core portion and a second core portion connected together, the first core portion and the second core portion being distributed along a first direction, and in a second direction, the minimum size of the first core portion is smaller than the size of the second core portion; the first direction is parallel to the axis of the core assembly, and the second direction is perpendicular to the first direction;

[0008] The adhesive film is wrapped around the periphery of the core assembly, and the adhesive film includes: a first adhesive portion and a second adhesive portion connected to each other, the first adhesive portion wrapping around the first core portion, and the second adhesive portion wrapping around the second core portion;

[0009] The elastic modulus of the first adhesive portion is greater than that of the second adhesive portion.

[0010] Optionally, the adhesive film has an adhesive film body, and a first elastic film and a second elastic film fixedly connected to the adhesive film body;

[0011] The first adhesive portion includes: the first elastic membrane and the portion of the adhesive membrane body used to connect the first elastic membrane; the second adhesive portion includes: the second elastic membrane and the portion of the adhesive membrane body used to connect the second elastic membrane;

[0012] The elastic modulus of the first elastic membrane is greater than that of the second elastic membrane.

[0013] Optionally, the first elastic film is located on the side of the adhesive film body opposite to the first core portion; the second elastic film is located on the side of the adhesive film body opposite to the second core portion.

[0014] Optionally, the elastic modulus of the first adhesive portion is 5 to 6 times that of the elastic modulus of the second adhesive portion.

[0015] Optionally, in the first direction, the height of the first adhesive portion is greater than or equal to the height of the first core portion.

[0016] Optionally, the adhesive film is connected to the periphery of each core assembly.

[0017] Optionally, the core assembly has two first core portions and a second core portion located between the two first core portions, wherein the two first core portions are fixedly connected to both sides of the second core portion in the first direction, respectively.

[0018] The adhesive film includes: two first adhesive portions and a second adhesive portion located between the two first adhesive portions, wherein the two first adhesive portions are fixedly connected to both sides of the second adhesive portion in the first direction respectively.

[0019] In this configuration, one second adhesive portion is wound around one second core portion, and two first adhesive portions are respectively wound around two first core portions.

[0020] Optionally, the height of the second core portion is three-fifths of the total height of the core assembly; the height of both first core portions is one-fifth of the total height of the core assembly.

[0021] Optionally, the core assembly includes: a positive electrode sheet and a negative electrode sheet, and a first separator located between the positive electrode sheet and the negative electrode sheet, wherein the positive electrode sheet, the first separator and the negative electrode sheet are stacked together and then wound to form the core assembly;

[0022] Wherein, the thickness of the portion of the positive electrode sheet located within the first core portion is less than the thickness of the portion of the positive electrode sheet located within the second core portion; the thickness of the portion of the negative electrode sheet located within the first core portion is less than the thickness of the portion of the negative electrode sheet located within the second core portion.

[0023] On the other hand, a battery is provided, comprising: a housing and a cell, wherein the cell is any of the cells described above, the housing having a receiving cavity, and the cell being located within the receiving cavity.

[0024] The beneficial effects of the technical solutions provided in this application include at least the following:

[0025] The adhesive film in the battery cell can be wound around the outer perimeter of the core assembly. The elastic modulus of the first adhesive portion of the adhesive film is greater than that of the second adhesive portion. Thus, after the adhesive film is wound around the core assembly, the first adhesive portion with the higher elastic modulus can wrap around the smaller first core portion, and the second adhesive portion with the lower elastic modulus can wrap around the larger second core portion. This ensures that the larger second core portion is tightly wound by the second adhesive portion with the lower elastic modulus, while also ensuring that the smaller first core portion is tightly wound by the first adhesive portion with the higher elastic modulus. This, in turn, ensures that the entire core assembly is tightly wound with the adhesive film, resulting in good overall adhesion between the positive and negative electrode plates in the core assembly and preventing poor lithium intercalation and lithium plating during battery cell operation. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of a battery cell provided in an embodiment of this application;

[0028] Figure 2 This is a schematic diagram of the adhesive film in a battery cell after it has been unfolded, according to an embodiment of this application.

[0029] Figure 3 This is a schematic diagram of a partially unfolded battery cell provided in an embodiment of this application;

[0030] Figure 4 This is a schematic diagram of the structure of an adhesive film provided in an embodiment of this application;

[0031] Figure 5This is a schematic diagram of another partially unfolded battery cell provided in an embodiment of this application. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0033] This application provides a battery cell, which can be a cylindrical battery cell. After assembling the battery cell, a cylindrical battery can be obtained.

[0034] Please refer to Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the structure of a battery cell provided in an embodiment of this application. Figure 2 This is a schematic diagram of the adhesive film in a battery cell after it has been unfolded, according to an embodiment of this application. The battery cell may include: a core assembly 100 and an adhesive film 200.

[0035] The winding assembly 100 in the battery cell may include a first winding portion 100a and a second winding portion 100b connected to each other. The first winding portion 100a and the second winding portion 100b in the winding assembly 100 may be distributed along a first direction X, and in a second direction Y, the minimum size of the first winding portion 100a may be smaller than the size of the second winding portion 100b. Here, the first direction X may be parallel to the axis of the winding assembly 100, and the second direction Y may be perpendicular to the first direction X.

[0036] For example, when the cell is a cylindrical cell, the minimum dimension of the first core portion 100a in the second direction Y is the minimum diameter of the first core portion 100a, and the dimension of the second core portion 100b in the second direction Y is the diameter of the second core portion 100b. That is, in the first direction X, the diameter of the first core portion 100a can gradually decrease along the direction of the first core portion 100a away from the second core portion 100b.

[0037] The adhesive film 200 in the battery cell can be wound around the periphery of the core assembly 100. Here, the side of the adhesive film 200 facing the core assembly 100 can be adhesive, so that the adhesive film 200 can be fixedly connected to the core assembly 100 by its own adhesiveness, thereby being used to fix the core assembly 100. The adhesive film 200 in the battery cell may include: a first adhesive portion 200a and a second adhesive portion 200b connected to each other. The first adhesive portion 200a can be wound around a first core portion 100a, and the second adhesive portion 200b can be wound around a second core portion 100b. That is, the first adhesive portion 200a and the second adhesive portion 200b in the adhesive film 200 can be arranged along a first direction X.

[0038] Please refer to the following for further explanation. Figure 3 , Figure 3 This is a schematic diagram of a partially unfolded battery cell according to an embodiment of this application. The core assembly 100 in the battery cell may include: a positive electrode 101 and a negative electrode 102, and a first separator 103 located between the positive electrode 101 and the negative electrode 102. The positive electrode 101, the first separator 103, and the negative electrode 102 in the core assembly 100 are stacked together and then wound to form the core assembly 100. Here, the core assembly 100 may also include a winding needle. The positive electrode 101, the first separator 103, and the negative electrode 102 can be wound onto the winding needle to form the core assembly 100.

[0039] In the core assembly 100, the thickness of the portion of the positive electrode 101 located within the first core portion 100a can be less than the thickness of the portion of the positive electrode 101 located within the second core portion 100b. Similarly, the thickness of the portion of the negative electrode 102 located within the first core portion 100a can be less than the thickness of the portion of the negative electrode 102 located within the second core portion 100b. Thus, after the positive electrode 101, the first separator 103, and the negative electrode 102 are stacked and wound together, due to the thickness difference between the positive electrode 101 and the negative electrode 102 within the first core portion 100a and the second core portion 100b, the adhesion between the portions of the positive electrode 101 and the negative electrode 102 located within the first core portion 100a is relatively poor.

[0040] It should be noted that the battery cell in this application can be a lithium-ion battery cell, which mainly relies on the movement of lithium ions between the positive and negative electrodes to operate. Here, during the operation of the battery cell, lithium ions can be inserted and extracted back and forth between the two positive electrode plates 101 and the negative electrode plate 102 to realize the charging and discharging process of the battery cell.

[0041] In the existing technology, the adhesive film cannot fix the core assembly according to the size difference between the first roll core and the second roll core. That is, while the adhesive film fixes the second roll core to ensure a good fit between the positive and negative electrode sheets located in the second roll core, the part of the adhesive film used to fix the first roll core cannot ensure a good fit between the positive and negative electrode sheets located in the first roll core. As a result, during the use of the battery cell, the first roll core is more prone to poor lithium insertion and lithium plating.

[0042] In this application, the elastic modulus of the first adhesive portion 200a in the adhesive film 200 can be greater than that of the second adhesive portion 200b. Thus, after the adhesive film 200 is wound around the core assembly 100, the first adhesive portion 200a with a larger elastic modulus can wrap around the smaller first core portion 100a, and the second adhesive portion 200b with a smaller elastic modulus can wrap around the larger second core portion 100b. This ensures that the larger second core portion 100b is tightly wound by the second adhesive portion 200b with a smaller elastic modulus, while also ensuring that the smaller first core portion 100a is tightly wound by the first adhesive portion 200a with a larger elastic modulus. This ensures that the entire core assembly 100 is tightly wound by the adhesive film 200, thus guaranteeing a good overall fit between the positive electrode 101 and the negative electrode 102 in the core assembly 100 and preventing poor lithium intercalation and lithium plating during cell operation.

[0043] In summary, this application provides a battery cell comprising: a core assembly and an adhesive film, the adhesive film being wound around the periphery of the core assembly. The elastic modulus of the first adhesive portion of the adhesive film is greater than that of the second adhesive portion. Thus, after the adhesive film is wound around the core assembly, the first adhesive portion with the larger elastic modulus can wrap around the smaller first core portion, and the second adhesive portion with the smaller elastic modulus can wrap around the larger second core portion. This ensures that the larger second core portion is tightly wound by the second adhesive portion with the smaller elastic modulus, while also ensuring that the smaller first core portion is tightly wound by the first adhesive portion with the larger elastic modulus. This ensures that the entire core assembly is tightly wound with the adhesive film, thus guaranteeing good overall adhesion between the positive and negative electrode sheets in the core assembly and preventing poor lithium intercalation and lithium plating during battery cell operation.

[0044] Optional, please refer to Figure 4 , Figure 4 This is a schematic diagram of the structure of an adhesive film provided in an embodiment of this application. The adhesive film 200 in the battery cell may have an adhesive film body 201, and a first elastic film 202 and a second elastic film 203 fixedly connected to the adhesive film body 201. The elastic modulus of the first elastic film 201 may be greater than the elastic modulus of the second elastic film 203.

[0045] For example, the first elastic membrane 201 can be made of an organic material with a high elastic modulus, and the second elastic membrane 203 can be made of an organic material with a low elastic modulus. For example, these organic materials can all be synthetic resins. That is, the first elastic membrane 201 can be made of a synthetic resin with a high elastic modulus, and the second elastic membrane 202 can be made of a synthetic resin with a low elastic modulus.

[0046] The first adhesive portion 200a may include: a first elastic membrane 202 and a portion of the adhesive membrane body 201 used for connecting the first elastic membrane 202. The second adhesive portion 200b may include: a second elastic membrane 203 and a portion of the adhesive membrane body 201 used for connecting the second elastic membrane 203.

[0047] Here, the adhesive film body 201 may not be elastic. The adhesive film body 201 only serves to fix and connect the first elastic film 202 and the second elastic film 203. Thus, when the elastic modulus of the first elastic film 202 is greater than the elastic modulus of the second elastic film 203, the elastic modulus of the first adhesive portion 200a can be greater than the elastic modulus of the second adhesive portion 200b.

[0048] It should be noted that in the adhesive film 200, the first elastic film 202 and the second elastic film 203 can be distributed on the same side of the adhesive film body 201. Furthermore, the sides of the first elastic film 202 and the sides of the second elastic film 203 distributed on the adhesive film body 201 are in contact with each other. This ensures that there are no gaps between the first elastic film 202 and the second elastic film 203 in the first direction X, thereby ensuring that the entire core assembly 100 can be wound with either the first elastic film 202 or the second elastic film 203 in the first direction X. In other words, the entire core assembly 100 can be bound in the first direction X, further ensuring a good overall fit between the positive electrode 101 and the negative electrode 102 in the core assembly 100.

[0049] Optionally, the first elastic film 202 in the adhesive film 200 can be located on the side of the adhesive film body 201 opposite to the first core portion 100a, and the second elastic film 203 can be located on the side of the adhesive film body 201 opposite to the second core portion 100b. It should be noted that the side of the adhesive film body 201 facing the core assembly 100 can be adhesive, and the adhesive film 200 can be fixedly connected to the core assembly 100 through its own adhesiveness. Thus, after the adhesive film 200 is wound around the core assembly 100, the first elastic film 202, fixedly connected to the adhesive film body 201, can tightly wind the first core portion 100a, and the second elastic film 203, fixedly connected to the adhesive film body 201, can tightly wind the second core portion 100b.

[0050] Optionally, the elastic modulus of the first adhesive portion 200a in the adhesive film 200 can be 5 to 6 times the elastic modulus of the second adhesive portion 200b. Here, since both the first elastic film 202 and the second elastic film 203 are fixedly connected to the adhesive film body 201, the elastic modulus of the first elastic film 202 can be 5 to 6 times the elastic modulus of the second elastic film 203, so that the elastic modulus of the first adhesive portion 200a can be 5 to 6 times the elastic modulus of the second adhesive portion 200b.

[0051] In this way, when the elastic modulus of the first adhesive portion 200a is 5 to 6 times that of the elastic modulus of the second adhesive portion 200b, it is possible to ensure that the larger second roll core portion 100b is tightly wound by the second adhesive portion 200b with a smaller elastic modulus, while also ensuring that the smaller first roll core portion 100a is tightly wound by the first adhesive portion 200a with a larger elastic modulus.

[0052] Optionally, in the first direction X, the height of the first adhesive portion 200a can be greater than or equal to the height of the first core portion 100a. This ensures that the entire first core portion 100a extending in the first direction X can be tightly wound by the first adhesive portion 200a, thereby ensuring a good fit between the portions of the positive electrode 201 and the negative electrode 202 located in the first core portion 100a, further preventing poor lithium intercalation and lithium plating during cell operation.

[0053] In this application, the outer periphery of the core assembly 100 in the battery cell is connected with an adhesive film 200, meaning that the adhesive film 200 can be wrapped around the core assembly 100 at least once. Thus, with the adhesive film 200 connected to the outer periphery of the core assembly 100, the core assembly 100 can be subjected to omnidirectional compression, thereby further ensuring a good overall fit between the positive electrode 201 and the negative electrode 202.

[0054] Optional, such as Figure 2 As shown, the core assembly 100 may have two first core portions 100a, and a second core portion 100b located between the two first core portions 100a and the two first core portions 100a. The two first core portions 100a may be fixedly connected to the two sides of the second core portion 100b1 respectively in the first direction X.

[0055] Here, the thickness of the portion of the positive electrode 101 located within the first core portion 100a in the core assembly 100 can be less than the thickness of the portion of the positive electrode 101 located within the second core portion 100b. That is, during the production of the positive electrode 101 using a coating process, there is a thinning area at the edge of the positive electrode 101, and the thickness of the thinning area is less than the thickness of the normal coating area.

[0056] Similarly, the thickness of the portion of the negative electrode sheet 102 located within the first core portion 100a in the core assembly 100 can be less than the thickness of the portion of the negative electrode sheet 102 located within the second core portion 100b. That is, during the production of the negative electrode sheet 102 using a coating process, there is a thinning area at the edge of the negative electrode sheet 102, and the thickness of the thinning area is less than the thickness of the normal coating area.

[0057] It should be noted that, please refer to Figure 5 , Figure 5 This is a schematic diagram of a partially unfolded battery cell according to another embodiment of this application. The wound core assembly 100 also includes a second separator 104, which is located on the side of the negative electrode 102 opposite to the positive electrode 101. The positive electrode 101, the first separator 103, the negative electrode 102, and the second separator 104 are stacked together and wound to form the wound core assembly 100. Here, after the wound core assembly 100 is formed, both the first separator 103 and the second separator 104 are used to prevent the positive electrode 101 and the negative electrode 102 from directly contacting each other, thereby avoiding short circuits and ensuring the normal operation of the battery cell.

[0058] It should also be noted that the overall thickness of the first diaphragm 103 is consistent and the overall thickness of the second diaphragm 104 is consistent. Thus, after the positive electrode 101, the first diaphragm 103, the negative electrode 102, and the second diaphragm 104 are stacked and wound together, the minimum size of the first roll core 100a is smaller than the size of the second roll core 100b, and the parts of the positive electrode 101 and the negative electrode 102 located in the first roll core 100a have a poor degree of adhesion.

[0059] Therefore, when the core assembly 100 has two first core portions 100a and a second core portion 100b located between the two first core portions 100a, the adhesive film 200 may include two first adhesive portions 200a and a second adhesive portion 200b located between the two first adhesive portions 200a. The two first adhesive portions 200a can be fixedly connected to both sides of the second adhesive portion 200b in the first direction X, respectively. In this way, the two first adhesive portions 200a can be distributed in a one-to-one correspondence with the two first core portions 100a, and the second adhesive portion 200b can be distributed in a corresponding correspondence with the second core portion 100b. Furthermore, the second adhesive portion 200b can be wound around the second core portion 100b, and the two first adhesive portions 200a can be wound around the two first core portions 100a respectively.

[0060] In this application, in the first direction X, the height of the second core portion 100b in the core assembly 100 can be three-fifths of the total height of the core assembly 100, and the height of each of the two first core portions 100a in the core assembly 100 can be one-fifth of the total height of the core assembly 100.

[0061] It should be noted that, in the first direction X, the total height of the adhesive film 200 can be the same as the total height of the core assembly 100. Therefore, to ensure that the height of the first adhesive portion 200a is greater than or equal to the height of the first core portion 100a in the first direction X, and thus ensure that the entire first core portion 100a extending in the first direction X can be tightly wound by the first adhesive portion 200a, the height of one of the second adhesive portions 200b in the adhesive film 200 can be less than or equal to three-fifths of the total height of the adhesive film 200, and the height of both first adhesive portions 200a in the adhesive film 200 can be greater than or equal to one-fifth of the total height of the adhesive film 200.

[0062] It should be noted that during the operation of the battery cell, the winding assembly 100 within the cell may expand. Furthermore, in the first direction X, the expansion of the center of the winding assembly 100 can be greater than the expansion of the two side edges; that is, the expansion of the second winding core portion 100b in the winding assembly 100 can be greater than the expansion of the first winding core portion 100a. Here, since the first winding core portion 100a and the second winding core portion 100b are a fixedly connected integral structure, and since the size of the first winding core portion 100a is smaller than the size of the second winding core portion 100b, after the second winding core portion 100b expands to a greater extent, the adhesion of the portions of the positive electrode sheet 101 and the negative electrode sheet 102 located within the first winding core portion 100a will be worse.

[0063] In this application, since the first roll core 100a is tightly wound by the first adhesive portion 200a with a larger elastic modulus, and the second roll core 100b is tightly wound by the second adhesive portion 200b with a smaller elastic modulus, the second adhesive portion 200b with a smaller elastic modulus can bind the second roll core 100b with a larger expansion degree, thereby reducing the expansion degree of the second roll core 100b. This prevents the portion of the positive electrode 101 and the negative electrode 102 located inside the first roll core 100a from deteriorating due to the expansion of the second roll core 100b, and further avoids the occurrence of poor lithium insertion and lithium plating during the operation of the battery cell.

[0064] Therefore, in the battery cell of this application, the adhesive film 200 can not only wrap the core assembly 100 to accommodate dimensional differences, ensuring a good overall fit between the positive electrode 101 and the negative electrode 102, but also restrain the core assembly 100 to accommodate expansion differences, further ensuring a good overall fit between the positive electrode 101 and the negative electrode 102. Thus, the adhesive film 200 in this application can effectively prevent poor lithium insertion and lithium plating during battery cell operation.

[0065] In summary, this application provides a battery cell comprising: a core assembly and an adhesive film, the adhesive film being wound around the periphery of the core assembly. The elastic modulus of the first adhesive portion of the adhesive film is greater than that of the second adhesive portion. Thus, after the adhesive film is wound around the core assembly, the first adhesive portion with the higher elastic modulus can wrap around the smaller first core portion, and the second adhesive portion with the lower elastic modulus can wrap around the larger second core portion. This ensures that the larger second core portion is tightly wound by the second adhesive portion with the lower elastic modulus, while also ensuring that the smaller first core portion is tightly wound by the first adhesive portion with the higher elastic modulus. This ensures that the entire core assembly is tightly wound with the adhesive film, thus guaranteeing good overall adhesion between the positive and negative electrode sheets in the core assembly and preventing poor lithium intercalation and lithium plating during core operation.

[0066] This application also provides a battery, including a casing and a battery cell. The battery cell can be the battery cell described in the above embodiments. The casing of the battery can have a receiving cavity, and the battery cell can be located in the receiving cavity of the casing.

[0067] It should be noted that after the battery cell is manufactured, it can be placed into the housing cavity of the casing, which may also contain electrolyte, thus assembling a battery. During the battery's operation, ions can be inserted and extracted between the positive and negative electrodes in the cell's winding assembly via the electrolyte, achieving the charging and discharging process and enabling the battery to function normally.

[0068] In this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "multiple" refers to two or more unless otherwise expressly defined.

[0069] The above description is merely an optional embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery cell, characterized in that, The battery cell includes: a core assembly (100) and an adhesive film (200); The core assembly (100) includes a first core portion (100a) and a second core portion (100b) connected to each other. The first core portion (100a) and the second core portion (100b) are distributed along a first direction (X), and in a second direction (Y), the minimum size of the first core portion (100a) is smaller than the size of the second core portion (100b). The first direction (X) is parallel to the axis of the core assembly (100), and the second direction (Y) is perpendicular to the first direction (X). The adhesive film (200) is wound around the periphery of the core assembly (100), and the adhesive film (200) includes: a first adhesive portion (200a) and a second adhesive portion (200b) connected to each other, the first adhesive portion (200a) being wound around the first core portion (100a), and the second adhesive portion (200b) being wound around the second core portion (100b); The elastic modulus of the first adhesive portion (200a) is greater than that of the second adhesive portion (200b).

2. The battery cell according to claim 1, characterized in that, The adhesive film (200) has an adhesive film body (201), and a first elastic film (202) and a second elastic film (203) fixedly connected to the adhesive film body (201); The first adhesive portion (200a) includes: the first elastic membrane (202) and the portion of the adhesive membrane body (201) for connecting the first elastic membrane (202); the second adhesive portion (200b) includes: the second elastic membrane (203) and the portion of the adhesive membrane body (201) for connecting the second elastic membrane (203); The elastic modulus of the first elastic membrane (202) is greater than that of the second elastic membrane (203).

3. The battery cell according to claim 2, characterized in that, The first elastic film (202) is located on the side of the adhesive film body (201) away from the first core portion (100a); the second elastic film (203) is located on the side of the adhesive film body (201) away from the second core portion (100b).

4. The battery cell according to any one of claims 1 to 3, characterized in that, The elastic modulus of the first adhesive portion (200a) is 5 to 6 times that of the elastic modulus of the second adhesive portion (200b).

5. The battery cell according to any one of claims 1 to 3, characterized in that, In the first direction (X), the height of the first adhesive portion (200a) is greater than or equal to the height of the first core portion (100a).

6. The battery cell according to any one of claims 1 to 3, characterized in that, The adhesive film (200) is connected to the periphery of each core assembly (100).

7. The battery cell according to any one of claims 1 to 3, characterized in that, The core assembly (100) has two first core portions (100a) and a second core portion (100b) located between the two first core portions (100a), wherein the two first core portions (100a) are fixedly connected to both sides of the second core portion (100b) in the first direction (X). The adhesive film (200) includes: two first adhesive portions (200a) and a second adhesive portion (200b) located between the two first adhesive portions (200a), wherein the two first adhesive portions (200a) are fixedly connected to both sides of the second adhesive portion (200b) in the first direction (X); In this configuration, one second adhesive portion (200b) is wound around one second core portion (100b), and two first adhesive portions (200a) are respectively wound around two first core portions (100a).

8. The battery cell according to claim 7, characterized in that, In the first direction (X), the height of the second core portion (100b) is three-fifths of the total height of the core assembly (100); the height of both first core portions (100a) is one-fifth of the total height of the core assembly (100).

9. The battery cell according to claim 1, characterized in that, The core assembly (100) includes: a positive electrode sheet (101) and a negative electrode sheet (102), and a first separator (103) located between the positive electrode sheet (101) and the negative electrode sheet (102). The positive electrode sheet (101), the first separator (103) and the negative electrode sheet (102) are stacked together and then wound to form the core assembly (100). The thickness of the portion of the positive electrode sheet (101) located within the first core portion (100a) is less than the thickness of the portion of the positive electrode sheet (101) located within the second core portion (100b); the thickness of the portion of the negative electrode sheet (102) located within the first core portion (100a) is less than the thickness of the portion of the negative electrode sheet (102) located within the second core portion (100b).

10. A battery, characterized in that it comprises: The housing and the battery cell, wherein the battery cell is the battery cell according to any one of claims 1 to 9, the housing has a receiving cavity, and the battery cell is located in the receiving cavity.

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