Battery monomer and battery pack

Abstract

The utility model provides a battery monomer and a battery pack, and relates to the technical field of batteries. The electrode assembly of the single battery comprises a first pole piece, a second pole piece, a diaphragm bag and a bonding layer, wherein the second pole piece and the first pole piece are arranged at an interval; the second pole piece comprises a foil layer and an active material layer; the diaphragm bag is provided with an accommodating cavity and is connected with the first pole piece; an opening communicated with the containing cavity is formed in the diaphragm bag, the active material layer is arranged on the foil layer, penetrates through the opening and is located in the containing cavity, the bonding layer is arranged on the foil layer, at least part of the bonding layer penetrates through the opening and is located in the containing cavity, and the bonding layer is bonded with the diaphragm bag. According to the battery monomer provided by the invention, the diaphragm bag is adopted, the active material layer penetrates through the opening of the diaphragm bag and is positioned in the accommodating cavity, and on the basis, the bonding layer bonded with the diaphragm bag is arranged on the foil layer. Therefore, the risk of mutual dislocation between the first pole piece and the second pole piece is reduced, and the production yield of the battery monomer is improved.

Description

Technical Field

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

[0002] The information disclosed in this background section is intended only to enhance the understanding of the general background of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art.

[0003] There are generally two types of electrode assembly fabrication for battery cells: winding and stacking. In the existing stacking process, a first electrode and a second electrode are stacked together, and a separator is stacked in a Z-shape between the first and second electrodes to form the electrode assembly. However, in this existing electrode assembly with the separator stacked in a Z-shape, the first and second electrodes are prone to misalignment under the traction of the separator in a vibrating environment, thus affecting the production yield of the battery cell. Utility Model Content

[0004] In view of this, the purpose of this application is to provide a battery cell and a battery pack, which aims to solve the technical problem in the prior art that the first electrode and the second electrode are prone to misalignment when the electrode assembly is in a vibrating environment.

[0005] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0006] In a first aspect, embodiments of this application provide a single battery cell, comprising:

[0007] An electrode assembly includes a first electrode, a second electrode, a diaphragm bag, and an adhesive layer. The second electrode is spaced apart from the first electrode. The diaphragm bag has a receiving cavity and an opening communicating with the receiving cavity. The second electrode includes a foil layer and an active material layer. The active material layer is disposed on the foil layer and passes through the opening located within the receiving cavity. The adhesive layer is disposed on the foil layer and at least a portion of the adhesive layer passes through the opening located within the receiving cavity. The adhesive layer is bonded to the diaphragm bag, and the diaphragm bag is connected to the first electrode.

[0008] In one embodiment of the first aspect, the active material layer is disposed on two opposite sides of the foil layer, the adhesive layer is located on at least one side of the foil layer, and the adhesive layer is spaced apart from the active material layer.

[0009] In one embodiment of the first aspect, the foil layer has a coating section, an adhesive section and a tab section connected in sequence, the active material layer is disposed on the coating section, the adhesive layer is disposed on the adhesive section, and the tab section is located outside the receiving cavity.

[0010] In one embodiment of the first aspect, the adhesive layer is disposed on two opposite sides of the foil layer to close the opening.

[0011] In one embodiment of the first aspect, the thickness of the adhesive layer is less than the thickness of the active material layer.

[0012] In one embodiment of the first aspect, the diaphragm bag includes a surface layer, a first protective layer, an insulating layer, and a second protective layer stacked together, the second protective layer being directly connected to the second electrode, and the surface layer being bonded to the first electrode.

[0013] In one embodiment of the first aspect, both the first protective layer and the second protective layer are ceramic layers, and the insulating layer is a polyethylene layer.

[0014] In one embodiment of the first aspect, the first electrode is a positive electrode and the second electrode is a negative electrode.

[0015] In one embodiment of the first aspect, the battery cell further includes a housing, the electrode assembly is located inside the housing, the housing is provided with a terminal post, and the portion of the second electrode located outside the receiving cavity is electrically connected to the terminal post.

[0016] Secondly, embodiments of this application provide a battery pack including the battery cells described in any of the embodiments of the first aspect above.

[0017] The beneficial effects of this application are as follows:

[0018] The battery cell provided in this application uses a separator bag instead of the existing separator. The active material layer of the second electrode passes through the opening of the separator bag and is located within the receiving cavity, thus separating the first and second electrodes. Furthermore, an adhesive layer is provided on the foil layer of the second electrode and connected to the separator bag to restrict relative movement between the separator bag and the second electrode. This effectively reduces the risk of misalignment between the first and second electrodes, thereby improving the production yield of the battery cell.

[0019] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This shows a schematic diagram of the electrode assembly from one perspective in the prior art;

[0022] Figure 2 This paper shows a schematic diagram of the electrode assembly from one perspective in one embodiment of the present application;

[0023] Figure 3 This paper shows a schematic diagram of the electrode assembly from another perspective in one embodiment of the present application;

[0024] Figure 4 This shows a schematic diagram of the second electrode and the adhesive layer from one perspective in one embodiment of this application;

[0025] Figure 5 A three-dimensional structural schematic diagram of the diaphragm bag and the second electrode sheet is shown in one embodiment of this application;

[0026] Figure 6 A partial structural schematic diagram of the diaphragm bag from one perspective is shown in one embodiment of this application.

[0027] Explanation of key component symbols:

[0028] Explanation of key component symbols in the prior art: 200 - electrode assembly; 210 - first electrode; 220 - second electrode; 230 - diaphragm;

[0029] Explanation of key component symbols in this application: 100 - Electrode assembly; 110 - First electrode; 111 - First tab; 120 - Second electrode; 121 - Foil layer; 1211 - Coated section; 1212 - Adhesive section; 1213 - Tab section; 12131 - Second tab; 122 - Active material layer; 130 - Diaphragm bag; 131 - Surface layer; 132 - First protective layer; 133 - Insulating layer; 134 - Second protective layer; 1341 - Receiving cavity; 1342 - Opening; 140 - Adhesive layer. Detailed Implementation

[0030] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0031] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0032] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0033] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0034] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0035] The manufacturing of electrode components for individual battery cells typically involves two types of processes: winding and stacking. For example... Figure 1As shown, in the existing lamination process, the first electrode 210 and the second electrode 220 are stacked, and the separator 230 is stacked in a Z-shape between the first electrode 210 and the second electrode 220 to form the electrode assembly 200. However, in the existing electrode assembly 200 with the separator 230 stacked in a Z-shape, the first electrode 210 and the second electrode 220 are prone to misalignment under the traction of the separator 230 when exposed to vibration, thus affecting the production yield of the battery cell.

[0036] In addition, the existing electrode assembly 200 with the separator 230 stacked in a Z-shape has the following problems: First, during the subsequent electrolyte injection process, the electrolyte washes over the edges of the electrode sheets, which can easily cause material to fall off. The fallen active material can self-discharge, which can easily reduce the capacity of the battery cell. Second, under high temperature conditions, the separator can easily shrink due to heat, causing the electrode sheets to be exposed and resulting in a short circuit. Third, the tabs can easily be inserted upside down between the first electrode sheet 210 and the second electrode sheet 220, causing a short circuit. Fourth, the foil layer of the electrode sheets is prone to breakage.

[0037] To address the aforementioned technical problems, firstly, embodiments of this application provide a single battery cell, relating to the field of battery technology, primarily used in battery packs for application in electrical devices such as new energy vehicles, ships, and spacecraft, or in energy storage devices such as energy storage containers and energy storage power stations. Of course, the single battery cell can also be directly applied to electrical devices or energy storage devices without using a battery pack; no specific limitations are placed on the application scenarios of the single battery cell here.

[0038] like Figure 2 , Figure 4 and Figure 5 As shown, the battery cell provided in this embodiment includes an electrode assembly 100, which includes a first electrode 110, a second electrode 120, a separator bag 130, and an adhesive layer 140.

[0039] The second electrode 120 and the first electrode 110 are arranged alternately, specifically, multiple second electrode 120s and multiple first electrode 110s are arranged along... Figure 2 The vertical spacing settings.

[0040] The diaphragm bag 130 has a receiving cavity 1341 and an opening 1342 communicating with the receiving cavity 1341. The second electrode 120 includes a foil layer 121 and an active material layer 122. The active material layer 122 is disposed on the foil layer 121 and passes through the opening 1342 within the receiving cavity 1341. An adhesive layer 140 is disposed on the foil layer 121, and at least a portion of the adhesive layer 140 passes through the opening 1342 within the receiving cavity 1341. The adhesive layer 140 is bonded to the diaphragm bag 130, and the diaphragm bag 130 is connected to the first electrode 110. That is, multiple first electrode 110s and multiple diaphragm bags 130 are staggered and stacked to form the electrode assembly 100.

[0041] For example, the adhesive layer 140 is composed of a combination of ceramic and hot melt adhesive, where 0 ≤ ceramic / hot melt adhesive < 1. Of course, the adhesive layer 140 can also be one of hot melt adhesive, acrylic adhesive, or double-sided tape; no specific limitation is made on the type of adhesive layer 140 here.

[0042] It should be noted that when the second electrode 120 is a negative electrode, the foil layer 121 can be made of copper foil, composite copper foil (the structure is similar to a "sandwich", mainly composed of "copper-polymer-copper", with polymer material as the substrate and metallic copper deposited on both sides), etc., and the active material layer 122 can be made of graphite, silicon, etc.; when the second electrode 120 is a positive electrode, the foil layer 121 can be made of aluminum foil, copper foil, etc., and the active material layer 122 can be made of lithium cobalt oxide, lithium iron phosphate, ternary lithium, lithium manganese oxide, etc., without specific restrictions.

[0043] It is understood that the battery cell provided in this embodiment uses a separator bag 130 instead of the existing separator, so that the active material layer of the second electrode 120 passes through the opening 1342 of the separator bag 130 and is located in the receiving cavity 1341, thereby separating the first electrode 110 and the second electrode 120 by the separator bag 130. Furthermore, by providing an adhesive layer 140 on the foil layer of the second electrode 120 and connecting the adhesive layer 140 to the separator bag 130, the relative movement of the separator bag 130 and the second electrode 120 is restricted. This effectively reduces the risk of misalignment between the first electrode 110 and the second electrode 120, thereby improving the production yield of the battery cell. At the same time, the adhesive layer 140 reduces the risk of short circuits caused by the tabs being inserted backwards between the first electrode 110 and the second electrode 120.

[0044] It should be noted that the adhesive layer 140 can be spaced apart from the first electrode 110 to reduce the influence of the first electrode 110 on the bonding effect. The "connection between the diaphragm bag 130 and the first electrode 110" mentioned above refers to the connection between the outer side of the diaphragm bag 130 (i.e., the side of the diaphragm bag 130 facing away from the active material layer 122) and the first electrode 110.

[0045] like Figure 2 , Figure 4 and Figure 5 As shown, in one embodiment, the active material layer 122 is disposed on two opposite sides of the foil layer 121, and the adhesive layer 140 is located on at least one side of the foil layer 121 (i.e., the adhesive layer 140 is disposed on at least one side of the foil layer 121), and the adhesive layer 140 is disposed at a distance from the active material layer 122.

[0046] Understandably, since both the active material layer 122 and the adhesive layer 140 are disposed on the foil layer 121, and the adhesive layer 140 and the active material layer 122 are spaced apart (i.e., they do not overlap), this reduces the possibility of increased thickness of the second electrode 120 due to the adhesive layer 140, which in turn reduces the energy density of the battery cell. Furthermore, placing the adhesive layer 140 on the foil layer 121 also facilitates processing.

[0047] like Figure 4 and Figure 5 As shown, the foil layer 121 further comprises a coating section 1211, an adhesive section 1212, and a tab section 1213 connected in sequence, i.e., the adhesive section 1212 is connected between the coating section 1211 and the tab section 1213, the active material layer 122 is disposed in the coating section 1211, the adhesive layer 140 is disposed in the adhesive section 1212, and the tab section 1213 is located outside the receiving cavity 1341.

[0048] It should be noted that the tab section 1213, i.e., the tab of the second electrode 120, is used for electrical connection with the terminal of the battery cell. When the second electrode 120 is a negative electrode, the tab section 1213 is a negative electrode electrically connected to the negative terminal; when the second electrode 120 is a positive electrode, the tab section 1213 is a positive electrode electrically connected to the positive terminal. No specific restrictions are made here.

[0049] It is understandable that the adhesive section 1212 and the tab section 1213 are the parts of the foil layer 121 that do not have the active material layer 122, also known as the blank part. The adhesive layer 140 is placed on the adhesive section 1212 to facilitate processing.

[0050] It should be noted that the "second electrode 120 and first electrode 110 are spaced apart" mentioned above refers to the active material layer 122 and the first electrode 110 being spaced apart, and the second electrode tab 12131 formed after cutting the foil layer 121 is also staggered from the first electrode tab 111 formed after cutting the first electrode 110. This reduces the risk of short circuit caused by contact between the first electrode tab 111 and the second electrode tab 12131. It should be further explained that, as... Figure 3 As shown, the staggered arrangement means that after the diaphragm bag 130 and the first electrode 110 are stacked, the first electrode tab 111 and the second electrode tab 12131 do not overlap in the direction perpendicular to the paper.

[0051] Furthermore, the adhesive layer 140 is disposed on two opposite sides of the foil layer 121 to close the opening 1342. This closes the opening 1342, so that when the second electrode 120 drops material, the dropped active material will be stably located in the receiving cavity 1341, reducing the possibility of the active material falling out of the opening 1342. In addition, the active material dropped from the first electrode 110 is also unlikely to enter the receiving cavity 1341 through the opening 1342 and contact the second electrode 120. This reduces the risk of the dropped active material self-discharging and affecting the capacity of the battery cell.

[0052] like Figure 5 As shown, the thickness of the adhesive layer 140 is less than the thickness of the active material layer 122. This makes the outer side of the separator bag 130 smoother, reducing the possibility that the surface of the separator bag 130 will have protrusions due to the adhesive layer 140, thus affecting the energy density of the battery.

[0053] Furthermore, the diaphragm bag 130 is positioned near the tab section 1213 on the side with the opening 1342. This allows the diaphragm bag 130 to nearly completely cover the adhesive section 1212, resulting in a larger contact area between the adhesive layer 140 and the diaphragm bag 130 and the second electrode 120, thereby increasing the strength of the bond.

[0054] like Figure 2 and Figure 6 As shown, in one embodiment, the diaphragm bag 130 includes a surface layer 131, a first protective layer 132, an insulating layer 133, and a second protective layer 134 stacked together. The second protective layer 134 is directly connected to the second electrode 120, and the surface layer 131 is bonded to the first electrode 110.

[0055] For example, the material of the surface layer 131 can be a material with adhesive bonding ability, such as polyvinylidene fluoride (PVDF) or polymethyl methacrylate (PMMA).

[0056] For example, the first protective layer 132 and the second protective layer 134 are both ceramic layers, and the insulating layer 133 is a polyethylene (PE) layer.

[0057] Understandably, by combining the adhesive layer 140 and the separator bag 130, the thickness of the inner layer can be eliminated. That is, the second protective layer 134 and the second electrode 120 can be directly connected without needing to be bonded through the inner layer. This reduces the thickness of the separator bag 130, providing more space for electrode stacking. With the same casing allowance (casing refers to the process of placing the electrode assembly 100 into the battery cell casing), the number of electrode layers can be increased, thereby improving the energy density of the battery cell. Furthermore, the first protective layer 132 and the second protective layer 134 provide protection for the electrode. The insulating layer 133 provides insulation, ensuring that the first electrode 110 and the second electrode 120 are mutually insulated.

[0058] like Figure 2 and Figure 6 As shown, exemplarily, the insulating layer 133 is located on the side of the second protective layer 134 opposite to the second electrode 120, the first protective layer 132 is located on the side of the insulating layer 133 opposite to the second electrode 120, and the surface layer 131 is located on the side of the first protective layer 132 opposite to the second electrode 120. Alternatively, the first protective layer 132 can be located on the side of the second protective layer 134 opposite to the second electrode 120, the insulating layer 133 can be located on the side of the first protective layer 132 opposite to the second electrode 120, and the surface layer 131 can be located on the side of the insulating layer opposite to the second electrode 120. No specific restrictions are placed on the stacking order of the aforementioned layered structures.

[0059] like Figure 5 As shown, the thickness of the foil layer 121 is T, which satisfies: 4.5μm≤T<8μm.

[0060] For example, the thickness T of the foil layer 121 can be selected from 4.5μm, 4.6μm, 4.7μm, 4.75μm, 4.8μm, 4.9μm, 5μm, 5.2μm, 5.5μm, 6μm, 6.3μm, 6.5μm, 7μm, 7.5μm, 7.9μm, etc., and no specific limitation is made here.

[0061] It is understandable that, such as Figure 1The existing electrode assembly 100 with the separator 230 stacked in a Z-shape requires a foil layer 121 thickness of 8μm or more to reduce the risk of foil breakage. However, by using the combination of adhesive layer 140 and separator bag 130, a foil layer 121 thickness of less than 8μm can be used. Under the action of adhesive layer 140, the risk of foil breakage can still be effectively reduced. The reduced thickness of foil layer 121 provides more space for electrode stacking. Under the same casing group margin, the number of electrode stacks can be increased, thereby improving the energy density of the battery cell.

[0062] In one embodiment, the first electrode 110 is the positive electrode, and the second electrode 120 is the negative electrode. The separator bag 130 is fitted onto the negative electrode, effectively separating the positive and negative electrodes. Furthermore, during the subsequent electrolyte injection process, the electrolyte can wash away the edges of the electrodes, causing active material to fall off, especially from the negative electrode. The separator bag 130 effectively mitigates this problem.

[0063] Of course, in the above embodiment, the first electrode 110 can also be the negative electrode and the second electrode 120 can be the positive electrode, that is, the separator bag 130 is sleeved on the positive electrode, which can also achieve the separation of the positive electrode and the negative electrode by the separator bag 130. Here, no specific restrictions are made on the types of the first electrode 110 and the second electrode 120.

[0064] In one embodiment, the battery cell includes a housing, an electrode assembly 100 located inside the housing, and a terminal post disposed on the housing. The portion of the second electrode 120 located outside the receiving cavity 1341 is electrically connected to the terminal post. It is understood that the housing can contain electrolyte to allow the electrolyte to wet the electrode assembly 100, and also serves to protect the electrode assembly 100.

[0065] Secondly, embodiments of this application provide a battery pack including the battery cells in any of the embodiments of the first aspect described above.

[0066] It should be understood that since the battery pack provided in this embodiment has the battery cell in any of the embodiments of the first aspect described above, it has all the beneficial effects of the battery cell, which will not be described in detail here.

[0067] To better illustrate the beneficial effects of the embodiments of this application, the electrochemical performance and safety performance testing process of the battery cell is provided here:

[0068] I. Test Methods: Test Group 1: The foil layer 121 of the negative electrode uses 4.5μm copper foil, with a total of 35 positive electrode sheets and 36 negative electrode sheets, using a Z-shaped stacked separator 230. Test Group 2: The foil layer 121 of the negative electrode uses 4.5μm copper foil, with a total of 35 positive electrode sheets and 36 negative electrode sheets, each negative electrode sheet using a separator bag 130 and an adhesive layer 140. Test Group 3: The foil layer 121 of the negative electrode uses 4.5μm copper foil, with a total of 35 positive electrode sheets and 36 negative electrode sheets, each negative electrode sheet using a separator bag 130, without using an adhesive layer 140. Test Group 4: The foil layer 121 of the negative electrode uses 8μm copper foil, with a total of 35 positive electrode sheets and 36 negative electrode sheets, each negative electrode sheet using a separator bag 130 and an adhesive layer 140. Test group 5: The foil layer 121 of the negative electrode uses 8μm copper foil, with a total of 35 positive electrode sheets and 36 negative electrode sheets, and a Z-shaped stacked separator 230.

[0069] The energy density of the battery cells in the above 5 test groups was calculated, and the thermal runaway trigger temperature was monitored. At the same time, the cells were disassembled to observe whether the electrodes were misaligned. The final electrochemical performance and safety performance test results of the battery cells are shown in the table below.

[0070] project Group yoke Energy density Are the electrodes misaligned? Thermal runaway trigger temperature Test Group 1 91.62％ 195.59Wh / kg yes 87℃ Test Group 2 91.62％ 195.60Wh / kg no 93℃ Test Group 3 91.62％ 195.54Wh / kg yes 90℃ Test group 4 91.58％ 187.38Wh / kg no 92℃ Test group 5 91.58％ 188.01Wh / kg yes 84℃

[0071] II. Test Conclusions: In test groups 1 to 5, under the same conditions of casing margin and copper foil thickness, compared with test groups using Z-shaped stacked separator 230 or only using separator bag 130 without adhesive layer 140, the test groups using separator bag 130 and adhesive layer 140 have higher energy density of individual cells, no electrode misalignment, and higher thermal runaway trigger temperature, thus exhibiting better electrochemical and safety performance.

[0072] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0073] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A battery cell, characterized in that, include: An electrode assembly (100) includes a first electrode (110), a second electrode (120), a diaphragm bag (130), and an adhesive layer (140). The second electrode (120) is spaced apart from the first electrode (110). The diaphragm bag (130) has a receiving cavity (1341) and an opening (1342) communicating with the receiving cavity (1341). The second electrode (120) includes a foil layer (121) and an active material layer (122). An active material layer (122) is disposed on the foil layer (121), and an active material layer (122) is disposed through the opening (1342) and located in the receiving cavity (1341). An adhesive layer (140) is disposed on the foil layer (121), and at least a portion of the adhesive layer (140) is disposed through the opening (1342) and located in the receiving cavity (1341). The adhesive layer (140) is bonded to the diaphragm bag (130), and the diaphragm bag (130) is connected to the first electrode (110).

2. The battery cell according to claim 1, characterized in that, The active material layer (122) is disposed on two opposite sides of the foil layer (121), the adhesive layer (140) is located on at least one side of the foil layer (121), and the adhesive layer (140) is disposed at a distance from the active material layer (122).

3. The battery cell according to claim 2, characterized in that, The foil layer (121) has a coating section (1211), an adhesive section (1212) and a tab section (1213) connected in sequence. The active material layer (122) is disposed in the coating section (1211), the adhesive layer (140) is disposed in the adhesive section (1212), and the tab section (1213) is located outside the receiving cavity (1341).

4. The battery cell according to claim 2, characterized in that, The adhesive layer (140) is disposed on two opposite sides of the foil layer (121) to close the opening (1342).

5. The battery cell according to claim 2, characterized in that, The thickness of the adhesive layer (140) is less than the thickness of the active material layer (122).

6. The battery cell according to claim 1, characterized in that, The diaphragm bag (130) includes a surface layer (131), a first protective layer (132), an insulating layer (133), and a second protective layer (134) stacked together. The second protective layer (134) is directly connected to the second electrode (120), and the surface layer (131) is bonded to the first electrode (110).

7. The battery cell according to claim 6, characterized in that, The first protective layer (132) and the second protective layer (134) are both ceramic layers, and the insulating layer (133) is a polyethylene layer.

8. The battery cell according to any one of claims 1 to 7, characterized in that, The first electrode (110) is a positive electrode, and the second electrode (120) is a negative electrode.

9. The battery cell according to any one of claims 1 to 7, characterized in that, The battery cell also includes a housing, the electrode assembly (100) is located inside the housing, the housing is provided with a pole post, and the portion of the second electrode (120) located outside the receiving cavity (1341) is electrically connected to the pole post.

10. A battery pack, characterized in that, Includes the battery cell according to any one of claims 1 to 9.

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