Battery cell and battery

Abstract

The invention 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] The present application relates to the field of battery technology, and in particular to a battery cell and a battery. Background Art

[0002] With the continuous development of battery technology, many electronic devices in daily life use lithium-ion batteries to provide power. At present, lithium-ion batteries are mainly composed of positive pole pieces, negative pole pieces, separators, electrolytes and shells. The positive pole pieces, separators and negative pole pieces that are wound together need to be placed in a shell containing electrolyte to form a battery cell. After the positive pole piece, separator and negative pole piece are wound, another circle of termination tape needs to be wound to fix the positive pole piece, separator and negative pole piece.

[0003] At present, in the process of producing positive and negative electrode sheets by coating process, due to equipment and process limitations, there is a thinning area at the edge of the sheet, and the thickness of the thinning area is less than the thickness of the normal coating area. As a result, after the positive electrode sheet, separator and negative electrode sheet are wound together, the degree of bonding between the edges of the positive and negative electrode sheets and the separator is poor, which increases the transmission path of lithium ions during the operation of the battery cell, making the battery cell more prone to poor lithium insertion and lithium plating.

[0004] However, the termination tape in the current battery cell cannot improve the degree of fit between the edges of the positive and negative electrodes and the separator, and thus cannot effectively improve the poor lithium insertion and lithium plating phenomena in the battery cell. Summary of the invention

[0005] The embodiment of the present application provides a battery cell and a battery. The problem of poor adhesion between the edges of the positive and negative electrode sheets and the separator in the prior art can be solved. The technical solution is as follows:

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

[0007] The core assembly comprises: a first core portion and a second core portion connected to each other, the first core portion and the second core portion are distributed along a first direction, and in the 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 wound around the periphery of the winding core assembly, and the adhesive film includes: a first adhesive portion and a second adhesive portion connected to each other, the first adhesive portion is wound around the first winding core portion, and the second adhesive portion is wound around the second winding core portion;

[0009] Wherein, the elastic modulus of the first adhesive portion is greater than the elastic modulus of the second adhesive portion.

[0010] Optionally, the adhesive film comprises 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 film and a portion of the adhesive film body used to connect the first elastic film; the second adhesive portion includes: the second elastic film and a portion of the adhesive film body used to connect the second elastic film;

[0012] Wherein, the elastic modulus of the first elastic film is greater than the elastic modulus of the second elastic film.

[0013] Optionally, the first elastic film is located on a side of the adhesive film body away from the first winding core; and the second elastic film is located on a side of the adhesive film body away from the second winding core.

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

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

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

[0017] Optionally, the core assembly comprises two first core portions and one second core portion located between the two first core portions, and the two first core portions are respectively fixedly connected to two sides of the second core portion in the first direction;

[0018] The adhesive film comprises: two first adhesive parts, and one second adhesive part located between the two first adhesive parts, and the two first adhesive parts are fixedly connected to two sides of the second adhesive part in the first direction respectively;

[0019] Among them, one second adhesive portion is wound around one second winding core portion, and two first adhesive portions are respectively wound around two first winding core portions.

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

[0021] Optionally, the winding 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, and the positive electrode sheet, the first separator and the negative electrode sheet are stacked together and then wound to form the winding core assembly;

[0022] Among them, the thickness of the portion of the positive electrode sheet located in the first winding core portion is smaller than the thickness of the portion of the positive electrode sheet located in the second winding core portion; the thickness of the portion of the negative electrode sheet located in the first winding core portion is smaller than the thickness of the portion of the negative electrode sheet located in the second winding core portion.

[0023] On the other hand, a battery is provided, comprising: a shell and a battery cell, wherein the battery cell is any of the battery cells described above, and the shell has a receiving cavity, and the battery cell is located in the receiving cavity.

[0024] The beneficial effects brought by the technical solution provided by the embodiment of the present application include at least:

[0025] The adhesive film in the battery cell can be wrapped around the periphery of the core assembly. The elastic modulus of the first adhesive part in the adhesive film is greater than the elastic modulus of the second adhesive part. In this way, after the adhesive film is wrapped around the core assembly, the first adhesive part with a larger elastic modulus can be wrapped around the first core part with a smaller size, and the second adhesive part with a smaller elastic modulus can be wrapped around the second core part with a larger size. In this way, while ensuring that the second core part with a larger size is tightly wrapped by the second adhesive part with a smaller elastic modulus, it can also ensure that the first core part with a smaller size can be tightly wrapped by the first adhesive part with a larger elastic modulus, thereby ensuring that the entire core assembly can be tightly wrapped by the adhesive film, thereby ensuring that the overall fit between the positive electrode sheet and the negative electrode sheet in the core assembly is good, and avoiding the occurrence of poor lithium insertion and lithium precipitation during the operation of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

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

[0028] Figure 2 is a schematic diagram of an adhesive film in a battery cell provided in an embodiment of the present application after unfolding;

[0029] Figure 3 is a schematic diagram of a battery cell partially unfolded according to an embodiment of the present application;

[0030] Figure 4 is a schematic structural diagram of an adhesive film provided in an embodiment of the present application;

[0031] Figure 5It is a schematic diagram of another battery cell provided in an embodiment of the present application after partial expansion. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below in conjunction with the accompanying drawings.

[0033] An embodiment of the present application provides a battery cell, which may be a cylindrical battery cell. After assembling the battery cells, a cylindrical battery can be obtained.

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

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

[0036] For example, when the battery cell is a cylindrical battery 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 in the direction in which the first core portion 100a is away from the second core portion 100b.

[0037] The adhesive film 200 in the battery cell can be wrapped around the periphery of the core assembly 100. Here, the side of the adhesive film 200 facing the core assembly 100 can be sticky, so that the adhesive film 200 can be fixedly connected to the core assembly 100 by its own adhesion, and then can be 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, the first adhesive portion 200a can be wrapped around the first core portion 100a, and the second adhesive portion 200b can be wrapped around the 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 the first direction X.

[0038] For clarification, please refer to Figure 3 , Figure 3 It is a schematic diagram of a battery cell partially unfolded according to an embodiment of the present application. The winding core assembly 100 in the battery cell may include: 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 in the winding core assembly 100 are stacked together and then wound to form the winding core assembly 100. Here, the winding core assembly 100 may also include a winding needle, and the positive electrode sheet 101, the first separator 103 and the negative electrode sheet 102 may be stacked together and then wound on the winding needle to form the winding core assembly 100.

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

[0040] It should be noted that the battery cell in the present application may be a lithium-ion battery cell, which mainly relies on the movement of lithium ions between the positive electrode and the negative electrode to work. Here, during the operation of the battery cell, lithium ions can be intercalated and deintercalated back and forth between the two positive electrode sheets 101 and the negative electrode sheets 102 to realize the charging and discharging process of the battery cell.

[0041] In the prior art, the adhesive film cannot fix the core assembly according to the size difference between the first core portion and the second core portion, that is, while the adhesive film is used to fix the second core portion to ensure that the positive electrode sheet and the negative electrode sheet are well fitted in the second core portion, the portion of the adhesive film used to fix the first core portion cannot ensure that the positive electrode sheet and the negative electrode sheet are well fitted in the first core portion. As a result, during the use of the battery cell, poor lithium insertion and lithium plating are more likely to occur in the first core portion.

[0042] In the present application, the elastic modulus of the first adhesive part 200a in the adhesive film 200 can be greater than the elastic modulus of the second adhesive part 200b. In this way, after the adhesive film 200 is wound around the core assembly 100, the first adhesive part 200a with a larger elastic modulus can be wound around the first core part 100a with a smaller size, and the second adhesive part 200b with a smaller elastic modulus can be wound around the second core part 100b with a larger size. In this way, while ensuring that the second core part 100b with a larger size is tightly wound by the second adhesive part 200b with a smaller elastic modulus, the first core part 100a with a smaller size can also be tightly wound by the first adhesive part 200a with a larger elastic modulus, thereby ensuring that the entire core assembly 100 can be tightly wound by the adhesive film 200, thereby ensuring that the overall bonding degree of the positive electrode sheet 101 and the negative electrode sheet 102 in the core assembly 100 is good, and avoiding the occurrence of poor lithium insertion and lithium precipitation during the operation of the battery cell.

[0043] In summary, the present application provides a battery cell, including: a core assembly and an adhesive film, and the adhesive film can be wrapped around the periphery of the core assembly. The elastic modulus of the first adhesive part in the adhesive film is greater than the elastic modulus of the second adhesive part. In this way, after the adhesive film is wrapped around the core assembly, the first adhesive part with a larger elastic modulus can be wrapped around the first core part with a smaller size, and the second adhesive part with a smaller elastic modulus can be wrapped around the second core part with a larger size. In this way, while ensuring that the second core part with a larger size is tightly wrapped by the second adhesive part with a smaller elastic modulus, it can also ensure that the first core part with a smaller size can be tightly wrapped by the first adhesive part with a larger elastic modulus, thereby ensuring that the entire core assembly can be tightly wrapped by the adhesive film, thereby ensuring that the overall fit between the positive electrode sheet and the negative electrode sheet in the core assembly is good, and avoiding the occurrence of poor lithium insertion and lithium precipitation during the operation of the battery cell.

[0044] Optional, please refer to Figure 4 , Figure 4 2 is a schematic diagram of the structure of an adhesive film provided in an embodiment of the present application. The adhesive film 200 in the battery cell may include 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] Exemplarily, the first elastic film 201 can be made of an organic material with a large elastic modulus, and the second elastic film 203 can be made of an organic material with a small elastic modulus. For example, these organic materials can all be synthetic resins. That is, the first elastic film 201 can be made of a synthetic resin with a large elastic modulus, and the second elastic film 202 can be made of a synthetic resin with a small elastic modulus.

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

[0047] Here, the adhesive film body 201 may not be elastic, and the adhesive film body 201 only serves to fix the first elastic film 202 and the second elastic film 203. In this way, 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 part 200a may be greater than the elastic modulus of the second adhesive part 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. And the side of the first elastic film 202 and the side of the second elastic film 203 distributed on the adhesive film body 201 are arranged in contact. In this way, it can be ensured that there is no gap between the first elastic film 202 and the second elastic film 203 in the first direction X, and further ensure that the entire core assembly 100 can be wound by the first elastic film 202 or the second elastic film 203 in the first direction X, that is, the entire core assembly 100 can be bound in the first direction X, further ensuring that the overall fit of the positive electrode sheet 101 and the negative electrode sheet 102 in the core assembly 100 is good.

[0049] Optionally, the first elastic film 202 in the adhesive film 200 may be located on the side of the adhesive film body 201 away from the first winding core 100a, and the second elastic film 203 may be located on the side of the adhesive film body 201 away from the second winding core 100b. It should be noted that the side of the adhesive film body 201 facing the winding core assembly 100 may be sticky, and the adhesive film 200 and the winding core assembly 100 may be fixedly connected together by the self-stickiness of the adhesive film body 201. In this way, after the adhesive film 200 is wound around the winding core assembly 100, the first elastic film 202 fixedly connected to the adhesive film body 201 can wrap the first winding core 100a tightly, and the second elastic film 203 fixedly connected to the adhesive film body 201 can wrap the second winding core 100b tightly.

[0050] Optionally, the elastic modulus of the first adhesive portion 200a in the adhesive film 200 may be 5 to 6 times the elastic modulus of the second adhesive portion 200b. Here, since the first elastic film 202 and the second elastic film 203 are both fixedly connected to the adhesive film body 201, the elastic modulus of the first elastic film 202 may 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 may 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 bonding part 200a is 5 to 6 times that of the second bonding part 200b, it can ensure that the second winding core 100b with a larger size is tightly wrapped by the second bonding part 200b with a smaller elastic modulus, while also ensuring that the first winding core 100a with a smaller size can be tightly wrapped by the first bonding part 200a with a larger elastic modulus.

[0052] Optionally, in the first direction X, the height of the first adhesive portion 200a may be greater than or equal to the height of the first winding core portion 100a. In this way, it can be ensured that the entire first winding core portion 100a extending in the first direction X can be tightly wound by the first adhesive portion 200a, thereby ensuring that the positive electrode sheet 201 and the negative electrode sheet 202 are well fitted in the first winding core portion 100a, further avoiding the occurrence of poor lithium insertion and lithium deposition during the operation of the battery cell.

[0053] In the present application, the outer periphery of the core assembly 100 in the battery cell is connected with an adhesive film 200, that is, the adhesive film 200 can be wrapped around the core assembly 100 at least once. In this way, after the outer periphery of the core assembly 100 is connected with the adhesive film 200, the core assembly 100 can be squeezed in all directions, which further ensures that the overall fit between the positive electrode sheet 201 and the negative electrode sheet 202 is good.

[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. The two first core portions 100a may be fixedly connected to both sides of the second core portion 100b1 in the first direction X, respectively.

[0055] Here, the thickness of the portion of the positive electrode sheet 101 in the core assembly 100 located in the first core portion 100a may be smaller than the thickness of the portion of the positive electrode sheet 101 located in the second core portion 100b, that is, in the process of producing the positive electrode sheet 101 using a coating process, a thinning area exists in the edge area of ​​the positive electrode sheet 101, and the thickness of the thinning area is smaller than the thickness of the normal coating area.

[0056] Similarly, the thickness of the portion of the negative electrode sheet 102 in the core assembly 100 located in the first core portion 100a may be smaller than the thickness of the portion of the negative electrode sheet 102 located in the second core portion 100b, that is, in the process of producing the negative electrode sheet 102 using a coating process, a thinning area exists at the edge of the negative electrode sheet 102, and the thickness of the thinning area is smaller than the thickness of the normal coating area.

[0057] Please note that, please refer to Figure 5 , Figure 5 1 is a schematic diagram of another battery cell partially unfolded according to an embodiment of the present application. The core assembly 100 also includes a second diaphragm 104, which is located on the side of the negative electrode sheet 102 away from the positive electrode sheet 101. The positive electrode sheet 101, the first diaphragm 103, the negative electrode sheet 102 and the second diaphragm 104 are stacked together to form the core assembly 100. Here, after the core assembly 100 is formed, the first diaphragm 103 and the second diaphragm 104 are used to prevent the positive electrode sheet 101 from directly contacting the negative electrode sheet 102, 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 separator 103 is consistent and the overall thickness of the second separator 104 is consistent. In this way, after the positive electrode sheet 101, the first separator 103, the negative electrode sheet 102 and the second separator 104 are stacked and wound together, the minimum size of the first winding core 100a is smaller than the size of the second winding core 100b, and the parts of the positive electrode sheet 101 and the negative electrode sheet 102 located in the first winding core 100a are poorly fitted.

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

[0060] In the present 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 the two first core portions 100a in the core assembly 100 can each 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 may be the same as the total height of the core assembly 100. To this end, in order to ensure that in the first direction X, the height of the first adhesive portion 200a may be greater than or equal to the height of the first core portion 100a, and further 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 second adhesive portion 200b in the adhesive film 200 may be less than or equal to three-fifths of the total height of the adhesive film 200, and the heights of the two first adhesive portions 200a in the adhesive film 200 may both 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 core assembly 100 in the battery cell may expand. And in the first direction X, the expansion of the middle part of the core assembly 100 can be greater than the expansion of the two side edges, that is, the expansion of the second core portion 100b in the core assembly 100 can be greater than the expansion of the first core portion 100a. Here, since the first core portion 100a and the second core portion 100b are an integral structure fixedly connected, and since the size of the first core portion 100a is smaller than that of the second core portion 100b, after the second core portion 100b expands to a greater extent, the degree of fit between the positive electrode sheet 101 and the negative electrode sheet 102 located in the first core portion 100a will be worse.

[0063] In the present application, since the first winding core 100a is tightly wound by the first adhesive part 200a with a larger elastic modulus, and the second winding core 100b is tightly wound by the second adhesive part 200b with a smaller elastic modulus, the second adhesive part 200b with a smaller elastic modulus can restrain the second winding core 100b with a larger expansion degree to reduce the expansion degree of the second winding core 100b, avoid the part of the positive electrode sheet 101 and the negative electrode sheet 102 located in the first winding core 100a from being poorly fitted due to the expansion of the second winding core 100b, and further avoid the occurrence of poor lithium insertion and lithium plating during the operation of the battery cell.

[0064] To this end, in the battery cell of the present application, the adhesive film 200 can not only wrap the core assembly 100 according to the size difference of the core assembly 100 to ensure that the overall fit between the positive electrode sheet 101 and the negative electrode sheet 102 in the core assembly 100 is good, but also can restrain the core assembly 100 according to the expansion difference of the core assembly 100 to further ensure that the overall fit between the positive electrode sheet 101 and the negative electrode sheet 102 in the core assembly 100 is good. In this way, the adhesive film 200 in the present application can effectively avoid the occurrence of poor lithium insertion and lithium precipitation during the operation of the battery cell.

[0065] In summary, the present application provides a battery cell, including: a core assembly and an adhesive film, and the adhesive film can be wrapped around the periphery of the core assembly. The elastic modulus of the first adhesive part in the adhesive film is greater than the elastic modulus of the second adhesive part. In this way, after the adhesive film is wrapped around the core assembly, the first adhesive part with a larger elastic modulus can be wrapped around the first core part with a smaller size, and the second adhesive part with a smaller elastic modulus can be wrapped around the second core part with a larger size. In this way, while ensuring that the second core part with a larger size is tightly wrapped by the second adhesive part with a smaller elastic modulus, it can also ensure that the first core part with a smaller size can be tightly wrapped by the first adhesive part with a larger elastic modulus, thereby ensuring that the entire core assembly can be tightly wrapped by the adhesive film, thereby ensuring that the overall fit between the positive electrode sheet and the negative electrode sheet in the core assembly is good, and avoiding the occurrence of poor lithium insertion and lithium precipitation during the operation of the core.

[0066] An embodiment of the present application further provides a battery, including a shell and a battery cell. The battery cell in the battery may be the battery cell in the above embodiment. The shell in the battery may have a accommodating cavity, and the battery cell may be located in the accommodating cavity in the shell.

[0067] It should be noted that after the battery cell is manufactured, the battery cell can be placed in the housing cavity of the shell, and the housing cavity of the shell can also contain electrolytes, so that a battery can be assembled. During the operation of the battery, ions can be embedded and de-embedded between the positive electrode sheet and the negative electrode sheet in the winding core assembly of the battery cell through the electrolyte to realize the electrical charging and discharging process, so that the battery can be used normally.

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

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

Claims

1. A battery cell, characterized in that: The battery core comprises: a winding core assembly (100) and an adhesive film (200); The core assembly (100) comprises: a first core portion (100a) and a second core portion (100b) connected to each other, wherein 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 winding core assembly (100), and the adhesive film (200) comprises: a first adhesive portion (200a) and a second adhesive portion (200b) connected to each other, the first adhesive portion (200a) is wound around the first winding core portion (100a), and the second adhesive portion (200b) is wound around the second winding core portion (100b); Wherein, the elastic modulus of the first adhesive portion (200a) is greater than the elastic modulus of the second adhesive portion (200b).

2. The battery cell according to claim 1, characterized in that: The adhesive film (200) comprises 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 bonding part (200a) comprises: the first elastic film (202) and a part of the bonding film body (201) used to connect the first elastic film (202); the second bonding part (200b) comprises: the second elastic film (203) and a part of the bonding film body (201) used to connect the second elastic film (203); Wherein, the elastic modulus of the first elastic film (202) is greater than the elastic modulus of the second elastic film (203).

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

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

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

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

9. The battery cell according to claim 1, characterized in that: The winding core assembly (100) comprises: 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 winding core assembly (100); The thickness of the portion of the positive electrode sheet (101) located in the first winding core portion (100a) is smaller than the thickness of the portion of the positive electrode sheet (101) located in the second winding core portion (100b); the thickness of the portion of the negative electrode sheet (102) located in the first winding core portion (100a) is smaller than the thickness of the portion of the negative electrode sheet (102) located in the second winding core portion (100b).

10. A battery, comprising: A shell and a battery cell, wherein the battery cell is the battery cell according to any one of claims 1 to 9, and the shell has a receiving cavity, and the battery cell is located in the receiving cavity.

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