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 single battery comprises an electrode assembly and a binding layer, the electrode assembly comprises a plurality of first pole pieces and a plurality of second pole pieces which are alternately stacked, and an isolation layer comprising a stacking layer and a winding layer, the starting end of the winding layer is fixedly connected with the second straight section of the stacking layer, and the binding layer is arranged between the first pole pieces and the second pole pieces; the winding layer wraps the first straight section and the second straight section in the circumferential direction of the electrode assembly, the terminating end of the winding layer is located on the side, away from the stacking layer, of the starting end, and at least part of the binding layer is wound outside the winding layer in the circumferential direction of the electrode assembly and connected with the winding layer. According to the battery monomer provided by the invention, the condition that stress is concentrated on the pole piece is relieved, so that the problem that the binding layer excessively binds the pole piece is solved, and the electrolyte can fully and uniformly infiltrate the electrode assembly.

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 manufacturing processes for battery cells: winding and stacking. For electrode assemblies manufactured using the stacking process, a binding layer is locally attached to the outside of the separator after stacking to bind the electrode and the separator. However, the binding layer can easily over-bind the electrode, making it difficult for the electrolyte to wet the electrode in that area, resulting in insufficient wetting of the electrode assembly. 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 of insufficient wetting of electrode components with attached binding layers.

[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 has a first direction, a second direction, and a third direction that intersect each other. The electrode assembly includes a plurality of first electrodes, a plurality of second electrodes, and an insulating layer. The insulating layer includes a stacked layer having a first straight segment, an insulating segment, and a second straight segment connected in sequence. The first straight segment and the second straight segment are arranged opposite each other along the third direction. A plurality of first electrodes and a plurality of second electrodes are located between the first straight segment and the second straight segment, and the plurality of first electrodes and the plurality of second electrodes are alternately stacked along the third direction. The insulating segment passes through each adjacent first electrode and second electrode. The insulating layer also includes a winding layer having a starting end and a terminating end that are far apart from each other. The starting end is fixedly connected to the second straight segment. The winding layer extends along the second direction and wraps around the first straight segment and the second straight segment along the circumference of the electrode assembly. The terminating end is located along the first direction on the side of the starting end away from the stacked layer.

[0008] A binding layer, at least a portion of which is wound around the outside of the winding layer along the circumferential direction of the electrode assembly and connected to the winding layer.

[0009] In one embodiment of the first aspect, the stacked layer and the wound layer are integrally formed to form the insulating layer.

[0010] In one embodiment of the first aspect, the winding layer is provided in multiple layers on both opposite sides of the electrode assembly along the third direction, and two adjacent winding layers along the third direction are stacked.

[0011] In one embodiment of the first aspect, at least a portion of the binding layer is wound in a ring around the outside of the winding layer in the circumferential direction.

[0012] In one embodiment of the first aspect, the binding layer includes a laminated adhesive layer, an insulating layer, and an expansion layer, the adhesive layer being disposed in conjunction with the winding layer.

[0013] In one embodiment of the first aspect, the insulating layer is located between the adhesive layer and the expansion layer; or

[0014] The expansion layer is located between the adhesive layer and the insulating layer.

[0015] In one embodiment of the first aspect, the termination end is located on one side of the electrode assembly along the first direction.

[0016] In one embodiment of the first aspect, the binding layer includes a first binding layer and a second binding layer, the first binding layer being wound around the outside of the winding layer in the circumferential direction of the electrode assembly, and the second binding layer being wound around the outside of the first binding layer in the circumferential direction of the electrode assembly.

[0017] In one embodiment of the first aspect, the battery cell further includes:

[0018] The housing has a receiving cavity and an opening communicating with the receiving cavity, the electrode assembly is disposed in the receiving cavity, and the binding layer is in direct contact with the housing;

[0019] A cover plate, connected to the housing to close the opening, the cover plate being provided with an injection hole communicating with the receiving cavity;

[0020] The electrode post is inserted through the cover plate and is electrically connected to the electrode assembly.

[0021] Secondly, embodiments of this application provide a battery pack including the battery cells described in any of the embodiments of the first aspect above.

[0022] The beneficial effects of this application are as follows:

[0023] The battery cell provided in this application has an electrode assembly in which the separator layer includes a stacked layer and a wound layer. The wound layer extends and wraps around the first and second straight sections of the stacked layer. The starting end of the wound layer is fixedly connected to the second straight section, and the ending end of the wound layer is located on the side of the starting end away from the stacked layer. At least a portion of the binding layer is wound around the wound layer along the circumference of the electrode assembly and is connected to the wound layer. That is, the separator layer separates each adjacent first and second electrode by the stacked layer, and then continues to wrap around the first and second straight sections of the stacked layer to finish the separation. Then, a binding layer is set around the wound layer along the circumference of the electrode assembly. In this way, since the adhesion between the separator layers is not as tight as that between the electrode and the separator layer, the binding force generated by the binding layer is difficult to release onto the electrode, thereby alleviating the stress concentration on the electrode. This improves the problem of the binding layer over-binding the electrode, allowing the electrolyte to more fully and uniformly wet the electrode assembly.

[0024] 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

[0025] 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.

[0026] Figure 1 This shows a schematic diagram of the assembly structure of the electrode assembly and the binding layer from one perspective in the prior art;

[0027] Figure 2 This illustration shows a schematic diagram of the assembly structure of the electrode assembly and the binding layer from one perspective in one embodiment of this application.

[0028] Figure 3 This illustration shows a schematic diagram of the assembly structure of the electrode assembly and the binding layer from another perspective in one embodiment of this application;

[0029] Figure 4 This illustration shows a schematic diagram of the assembly structure of the electrode assembly and the binding layer from one perspective in another embodiment of this application.

[0030] Figure 5 It shows Figure 4 A schematic diagram of the middle electrode assembly from one perspective;

[0031] Figure 6 It shows Figure 4 A schematic diagram of the middle isolation layer from one perspective;

[0032] Figure 7 It shows Figure 6 A schematic diagram of the structure of the interlayered layers from one perspective;

[0033] Figure 8 It shows Figure 6 A schematic diagram of the structure of the middle winding layer from one perspective;

[0034] Figure 9 A schematic diagram of the structure of the first binding layer in one embodiment of this application is shown.

[0035] Explanation of key component symbols:

[0036] Explanation of key component symbols in the prior art: 310 - first electrode; 320 - second electrode; 330 - insulating layer; 340 - binding layer;

[0037] Explanation of key component symbols in this application: 100 - Electrode assembly; 110 - First electrode; 120 - Second electrode; 130 - Insulation layer; 131 - Stacked layer; 1311 - First straight section; 1312 - Second straight section; 1313 - Insulation section; 132 - Winding layer; 1321 - Start end; 1322 - End end; 200 - Binding layer; 210 - First binding layer; 211 - Adhesive layer; 212 - Insulating layer; 213 - Expansion layer; 220 - Second binding layer; X - First direction; Y - Second direction; Z - Third direction. Detailed Implementation

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] Battery cells are a crucial component of battery packs, and the electrode components for battery cells are typically manufactured using two methods: winding and stacking. For electrode components manufactured using the stacking process, such as... Figure 1 As shown, in existing lamination processes, multiple first electrodes 310 and multiple second electrodes 320 are stacked, and an isolation layer 330 (also called a separator) is inserted in a Z-shape between each adjacent first electrode 310 and second electrode 320. That is, the first electrodes 310, second electrodes 320, and isolation layer 330 are stacked alternately. After the electrode assembly is fabricated, a binding layer 340 is locally attached to the outside of the isolation layer 330 to bind the electrodes and the isolation layer 330. However, the binding layer can easily over-bind the electrodes, causing stress to concentrate at the position corresponding to the electrode and the binding layer. This makes it difficult for the electrolyte to wet the electrode at that location, resulting in insufficient wetting of the electrode assembly.

[0044] In addition, the inventors discovered through research that existing battery cells also have the following problems: during the formation process, the stress generated between the electrode and the separator cannot be released due to the adhesion and binding of the separator, which makes the electrode prone to wrinkling; in the later stages of battery cell cycling, the binder added to the active material of the electrode is prone to failure, which makes the active material prone to falling off; the separator is prone to thermal shrinkage when heated, which can easily lead to electrode exposure and short circuit.

[0045] 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, to be indirectly applied 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.

[0046] like Figures 2 to 5 As shown, the battery cell provided in this embodiment includes an electrode assembly 100 and a binding layer 200.

[0047] The electrode assembly 100 has a first direction X, a second direction Y, and a third direction Z that intersect each other. The electrode assembly 100 includes a plurality of first electrodes 110, a plurality of second electrodes 120, and an isolation layer 130. The isolation layer 130 includes a stacked layer 131, which has a first straight section 1311, an isolation section 1313, and a second straight section 1312 connected in sequence. The first straight section 1311 and the second straight section 1312 are arranged opposite each other along the third direction Z. The plurality of first electrodes 110 and the plurality of second electrodes 120 are located between the first straight section 1311 and the second straight section 1312, and the plurality of first electrodes 110 and the plurality of second electrodes 120 are alternately stacked along the third direction Z. The isolation section 1313 passes through each adjacent first electrode 110 and second electrode 120. The insulating layer 130 further includes a winding layer 132 having a starting end 1321 and a ending end 1322 that are spaced apart from each other. The starting end 1321 is fixedly connected to the second straight segment 1312. The winding layer 132 extends along the second direction Y and wraps around the first straight segment 1311 and the second straight segment 1312 along the circumference of the electrode assembly 100. The ending end 1322 is located along the first direction X on the side of the starting end 1321 opposite to the stacked layer 131. At least a portion of the binding layer 200 is wound around the winding layer 132 along the circumference of the electrode assembly 100 and is connected to the winding layer 132.

[0048] For example, the first electrode 110 is a positive electrode and the second electrode 120 is a negative electrode. Of course, the first electrode 110 can also be a negative electrode and the second electrode 120 a positive electrode. There is no specific limitation on the type of electrode. The fixed connection between the starting end 1321 and the second straight section 1312 can be a heat-fusion connection, an integral molding connection, a snap-fit ​​connection, etc. There is no specific limitation here.

[0049] For example, when the electrode assembly 100 has length, width and thickness, the first direction X is the width direction of the electrode assembly 100, the second direction Y is the length direction of the electrode assembly 100, and the third direction Z is the thickness direction of the electrode assembly 100. No specific restrictions are made on the first direction X, the second direction Y and the third direction Z here.

[0050] It is understood that in the battery cell provided in this embodiment, the separator layer 130 in its electrode assembly 100 includes a stacked layer 131 and a winding layer 132. The winding layer 132 extends and wraps around the first straight section 1311 and the second straight section 1312 of the stacked layer 131. The starting end 1321 of the winding layer 132 is fixedly connected to the second straight section 1312. The ending end 1322 of the winding layer 132 is located on the side of the starting end 1321 away from the stacked layer 131. At least a portion of the binding layer 200 is wound around the winding layer 132 along the circumference of the electrode assembly 100 and is connected to the winding layer 132.

[0051] In other words, the above structure means that, based on the separation of each adjacent first electrode 110 and second electrode 120 by the stacked layer 131, the insulating layer 130 is further wrapped around the first straight section 1311 and the second straight section 1312 of the stacked layer 131 by the winding layer 132, and then the binding layer 200 is provided along the circumference of the electrode assembly 100. In this way, since the adhesion between the insulating layers 130 is not as tight as that between the electrode and the insulating layer 130, the binding force generated by the binding layer 200 is difficult to be released onto the electrode, thereby alleviating the stress concentration on the electrode. This improves the problem of the binding layer 200 over-binding the electrode, allowing the electrolyte to more fully and uniformly wet the electrode assembly 100.

[0052] like Figure 2As shown, in one embodiment, the winding layer 132 wraps around the first straight section 1311 and the second straight section 1312 with a preset number of turns, the preset number of turns being n, satisfying: n≥1.5, that is, the isolation layer 130, based on the stacked layer 131 separating each adjacent first electrode 110 and second electrode 120, continues to wrap around the winding layer 132 for at least 1.5 turns to finish, and then a binding layer 200 is provided outside the winding layer 132 along the circumference of the electrode assembly 100, which further alleviates the stress concentration on the electrode, thereby more effectively improving the problem of the binding layer 200 over-binding the electrode, so that the electrolyte can more fully and evenly wet the electrode assembly 100.

[0053] For example, the preset number of revolutions n can be selected as 1.5, 1.6, 1.8, 2, 2.1, 2.2, 2.5, 3, 4, 5, etc., without specific limitations. It should be noted that... Figure 2 The diagram shown is a schematic of the winding layer 132 wrapped around the first straight section 1311 and the second straight section 1312 in 1.5 turns. It is for illustrative purposes only and should not be construed as a limitation of this application.

[0054] like Figures 5 to 8 As shown, further, it satisfies: n≥2.5.

[0055] For example, the preset number of revolutions n can be selected as 2.5, 2.6, 2.8, 2.9, 3, 3.2, 3.3, 3.5, 3.8, 4, 4.5, 4.8, 5, 6, 7, etc., without specific limitations. It should be noted that... Figure 4 The diagram shown is a schematic of the winding layer 132 wrapped around the first straight section 1311 and the second straight section 1312 in 2.5 turns. It is for illustrative purposes only and should not be construed as a limitation of this application.

[0056] Understandably, by controlling the preset number of turns n to be greater than or equal to 2.5, that is, after the winding layer 132 wraps around the first straight section 1311 and the second straight section 1312 for 1.5 turns, the winding layer 132 continues to wrap for at least 1 more turn. This can not only improve the insufficient wetting of the electrode assembly 100, but also transfer the stress between the electrode and the separator 130 to the separator 130 and the binding layer 200. This can transfer the wrinkling phenomenon of the electrode to the binding layer 200. The wrinkling of the binding layer 200 does not affect the performance of the battery cell, while the wrinkling phenomenon of the electrode is greatly improved, which is ultimately beneficial to the performance of the battery cell.

[0057] In one embodiment, the stacked layer 131 and the wound layer 132 are integrally formed to form the isolation layer 130. It is understood that by integrally forming, the isolation layer 130 can have higher structural strength and structural stability.

[0058] like Figure 4 As shown, in one embodiment, the winding layer 132 is provided with multiple layers on both opposite sides of the electrode assembly 100 along the third direction Z, such as 2 layers, 3 layers, 4 layers, etc. This can save the amount of winding layer 132 while effectively improving the insufficient wetting of the electrode assembly 100 and the wrinkling of the electrode sheet, thereby reducing the manufacturing cost of the battery cell.

[0059] like Figure 2 and Figure 4 As shown, in one embodiment, at least a portion of the binding layer 200 is wound in a ring around the outside of the winding layer 132 along the circumferential direction.

[0060] It is understandable that, based on the finishing by winding layer 132, at least a portion of binding layer 200 is wound in a circular shape along the circumference of winding layer 132, that is, the winding trajectory of binding layer 200 forms a closed loop, which can effectively reduce the risk of short circuit caused by thermal shrinkage of insulating layer 130 leading to exposure of electrode sheet.

[0061] For example, a portion of the binding layer 200 may be wound in a ring around the winding layer 132 in the circumferential direction, in which case the binding layer 200 has a remaining amount in addition to the ring-wound portion; of course, the entire binding layer 200 may be wound in a ring around the winding layer 132 in the circumferential direction, in which case the binding layer 200 has no remaining amount, that is, the winding length of the binding layer 200 just forms a closed ring shape.

[0062] like Figure 9 As shown, in one embodiment, the binding layer 200 includes an adhesive layer 211, an insulating layer 212 and an expansion layer 213 stacked together, with the adhesive layer 211 attached to the winding layer 132.

[0063] For example, the adhesive layer 211 can be made of materials with adhesive properties such as acrylic glue, AB glue, and double-sided tape; the insulating layer 212 can be made of materials with insulating properties such as polyethylene (PE) and polyvinyl chloride (PVC); the expansion layer 213 can be made of one of the following three types: 1. Inorganic foaming agent: sodium bicarbonate, ammonium carbonate, etc.; 2. Organic foaming agent: azo compounds, nitroso compounds, sulfonyl hydrazine compounds, etc.; 3. Physical foaming agent: pentane, hexane, etc.

[0064] It is understandable that the adhesive layer 211 enables the binding layer 200 to be bonded to the winding layer 132, thereby connecting the binding layer 200 and the winding layer 132. The insulating layer 212 provides insulation between the electrode assembly 100 and the housing after it is installed, thus eliminating the need for the existing Mylar film (a polyester film mainly used to wrap and protect the electrode assembly 100) wrapped around the outside of the electrode assembly 100. This allows the binding layer 200 to directly contact the housing, saving space for the electrode assembly 100 and improving the energy density of the battery cell. With the expansion layer 213, after the electrode assembly 100 is installed, in the later stages of battery cell cycling, the expansion layer 213 allows the binding layer 200 to expand and adhere to the housing, working in conjunction with the housing to provide strong constraint on the electrode assembly 100. This reduces the possibility of active material detachment from the electrode sheets and improves the lifespan of the battery cell.

[0065] It should be noted that, in addition to setting the adhesive layer 211 to connect the binding layer 200 and the winding layer 132, the binding layer 200 can also be connected to the winding layer 132 by snap-fit. No specific restrictions are placed on the way the binding layer 200 and the winding layer 132 are connected here.

[0066] It should be noted that, for example, the positional relationship between the adhesive layer 211, the insulating layer 212, and the expansion layer 213 can be such that the insulating layer 212 is located between the adhesive layer 211 and the expansion layer 213, or the expansion layer 213 is located between the adhesive layer 211 and the insulating layer 212. Neither of these will affect the function of the three layers. Therefore, no specific restrictions are made on the positional relationship between the adhesive layer 211, the insulating layer 212, and the expansion layer 213.

[0067] like Figure 2 and Figure 4 As shown, in one embodiment, the termination end 1322 is located on one side of the electrode assembly 100 along the first direction X. Since this side is the side with a relatively small area, while the expansion of the electrode assembly 100 mainly occurs on the side with a relatively large area, by arranging the termination end 1322 on the side with a relatively small area, that is, the wrapping end of the winding layer 132 is located on one side of the electrode assembly 100 along the first direction X, the effect of the expansion of the electrode assembly 100 on the winding layer 132 can be improved, thereby reducing the risk of the winding layer 132 falling off at the end position.

[0068] In the above embodiment, in other words, the two opposite sides of the electrode assembly 100 along the first direction X are small faces, and the two opposite sides of the electrode assembly 100 along the third direction Z are large faces. Both the large and small faces extend along the second direction Y and are perpendicular to each other. The termination end 1322 of the winding layer 132 is located on the small face. It can be understood that the small face is the part with a smaller area on the electrode assembly 100, and the large face is the part with a larger area on the electrode assembly 100. With the use of the battery cell, the electrode assembly 100 is prone to expansion, and the expansion phenomenon is mainly concentrated on the large face. By setting the termination end 1322 of the winding layer 132 on the small face, the possibility of the winding layer 132 falling off due to the expansion of the electrode assembly 100 can be reduced.

[0069] like Figure 2 and Figure 4 As shown, in one embodiment, the binding layer 200 includes a first binding layer 210 and a second binding layer 220. The first binding layer 210 is wound around the outside of the winding layer 132 along the circumferential direction of the electrode assembly 100, and the second binding layer 220 is wound around the outside of the first binding layer 210 along the circumferential direction of the electrode assembly 100. It can be understood that the electrode assembly 100 can be better constrained through multiple binding layers.

[0070] It should be noted that, since the isolation layer 130 separates the first electrode 110 and the second electrode 120 through the stacked layer 131, and is further wrapped around the first straight section 1311 and the second straight section 1312 of the stacked layer 131 by the winding layer 132, although multiple layers of binding are provided, the binding forces generated by the first binding layer 210 and the second binding layer 220 are still difficult to be released onto the electrode, and the electrolyte can still fully and evenly wet the electrode assembly 100.

[0071] It should be noted that when the binding layer 200 includes the adhesive layer 211, insulating layer 212 and expansion layer 213 mentioned above, it means that the first binding layer 210 includes the adhesive layer 211, insulating layer 212 and expansion layer 213, and / or the second binding layer 220 includes the adhesive layer 211, insulating layer 212 and expansion layer 213. That is, at least one of the first binding layer 210 and the second binding layer 220 adopts a multilayer structure of adhesive layer 211, insulating layer 212 and expansion layer 213.

[0072] In one embodiment, the battery cell further includes a housing, a cover plate, and terminals. The housing has a receiving cavity and an opening communicating with the receiving cavity. The electrode assembly 100 is disposed within the receiving cavity, and the binding layer 200 is in direct contact with the housing. The cover plate is connected to the housing to close the opening, and the cover plate has an injection hole communicating with the receiving cavity. The terminals pass through the cover plate and are electrically connected to the electrode assembly 100.

[0073] It is understandable that the aforementioned insertion into the housing refers to the process of placing the electrode assembly 100 into the receiving cavity through the opening of the housing. Since the binding layer 200 has an insulating layer 212, the traditional Mylar film wrapped around the electrode assembly 100 can be eliminated. This allows the binding layer 200 to directly contact the housing, thereby saving a significant amount of space for the electrode assembly 100 and improving energy density.

[0074] During the electrolyte injection process, the electrolyte is injected into the receiving cavity through the injection hole, thereby wetting the electrode assembly 100. During the wetting process, since the isolation layer 130 has semi-permeable properties, the electrolyte can pass through the isolation layer 130 to contact the first electrode 110 and the second electrode 120 for wetting.

[0075] The electrode post is electrically connected to the electrode assembly 100 to serve as the positive or negative terminal of an external circuit. For example, when the first electrode 110 is the positive electrode and the second electrode 120 is the negative electrode, if the electrode post is the positive electrode post, it is connected to the tab of the first electrode 110 to serve as the positive terminal of the external circuit; if the electrode post is the negative electrode post, it is connected to the tab of the second electrode 120 to serve as the negative terminal of the external circuit.

[0076] Secondly, embodiments of this application provide a battery pack including the battery cells in any of the embodiments of the first aspect described above.

[0077] It is understood that since the battery pack provided in this embodiment has the battery cell in any of the embodiments of the first aspect, it has all the beneficial effects of the battery cell, which will not be described in detail here.

[0078] To better illustrate the beneficial effects of the embodiments of this application, the electrical performance testing process of a single battery cell is provided herein:

[0079] I. Test Methods: Test Group 1: The winding layer 132 is wrapped around the first straight section 1311 and the second straight section 1312 with 2.5 turns. The binding layer 200 is wrapped around the electrode assembly 100 in a ring shape. There is no Mylar film, and the shell grouping margin is 91.5%. Test Group 2: The winding layer 132 is wrapped around the first straight section 1311 and the second straight section 1312 with 2.5 turns. The binding layer 200 is partially attached to the outside of the electrode assembly 100. There is a Mylar film. The shell grouping margin is 91%. 0.5%; Test Group 3: The winding layer 132 is wrapped around the first straight section 1311 and the second straight section 1312 with 1.5 turns, and the binding layer 200 is wrapped around the electrode assembly 100 in a ring shape. There is no Mylar film, and the shell grouping margin is 91.5%; Test Group 3: The winding layer 132 is wrapped around the first straight section 1311 and the second straight section 1312 with 0.5 turns, and the binding layer 200 is partially attached to the outside of the electrode assembly 100. There is a Mylar film, and the shell grouping margin is 91.5%.

[0080] In the above test groups 1 to 3, the materials and formulas of the electrode components 100 are the same, and the electrolyte is injected according to the coefficient of 3.2. The same chemical composition and capacity-building steps are used. The performance test results are shown in the table below.

[0081]

[0082] II. Test Conclusions: Compared to Test Group 2, Test Group 1 omits the Mylar film and uses a binding layer 200 with an adhesive layer 211, an insulating layer 212, and an expansion layer 213. This improves the initial discharge energy and cycle retention rate of the battery cells, while reducing the number of wrinkled electrodes, resulting in superior electrical performance. Compared to Test Group 3, Test Group 1 uses a preset number of turns n = 2.5, meaning an additional turn on top of the 1.5 turns in Test Group 3. This improves both the initial discharge energy and cycle retention rate of the battery cells, while reducing the number of wrinkled electrodes, resulting in superior electrical performance. Compared to Test Group 4, Test Group 2 also uses a preset number of turns n = 2.5, compared to 0.5 turns in Test Group 4. This improves both the initial discharge energy and cycle retention rate of the battery cells, while reducing the number of wrinkled electrodes, resulting in superior electrical performance.

[0083] 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.

[0084] 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 by, The electrode assembly (100) has a first direction (X), a second direction (Y) and a third direction (Z) intersecting with each other, and comprises a plurality of first electrode tabs (110), a plurality of second electrode tabs (120) and a separation layer (130). The separation layer (130) comprises a stacked layer (131) having a first flat section (1311), a separation section (1313) and a second flat section (1312) connected in sequence. The first flat section (1311) and the second flat section (1312) are oppositely arranged along the third direction (Z). The plurality of first electrode tabs (110) and the plurality of second electrode tabs (120) are located between the first flat section (1311) and the second flat section (1312), and are alternately stacked along the third direction (Z). The separation section (1313) is arranged between each adjacent first electrode tab (110) and second electrode tab (120). The separation layer (130) further comprises a winding layer (132) having a starting end (1321) and a terminal end (1322) away from each other. The starting end (1321) is fixedly connected to the second flat section (1312). The winding layer (132) extends along the second direction (Y) and is wrapped around the first flat section (1311) and the second flat section (1312) along the circumferential direction of the electrode assembly (100). The terminal end (1322) is located on the side of the electrode assembly (100) away from the stacked layer (131) along the first direction (X). A binding layer (200) is wrapped around the winding layer (132) along the circumferential direction of the electrode assembly (100) and is connected to the winding layer (132). The stacked layer (131) and the winding layer (132) are integrally formed into the separation layer (130).

2. The battery cell of claim 1, wherein, The winding layer (132) is provided with a plurality of layers on both sides of the electrode assembly (100) along the third direction (Z). Two adjacent winding layers (132) along the third direction (Z) are stacked.

3. The battery cell of claim 1, wherein, At least part of the binding layer (200) is wrapped around the winding layer (132) along the circumferential direction of the winding layer (132).

4. The battery cell of claim 1, wherein, The binding layer (200) comprises a bonding layer (211), an insulation layer (212) and an expansion layer (213) stacked together. The bonding layer (211) is arranged on the winding layer (132).

5. The battery cell of claim 1, wherein, The insulation layer (212) is located between the bonding layer (211) and the expansion layer (213); or 6. The battery cell of claim 5, wherein, The expansion layer (213) is located between the bonding layer (211) and the insulation layer (212). The terminal end (1322) is located on one side of the electrode assembly (100) along the first direction (X).

7. The battery cell according to any one of claims 1 to 6, characterized in that, ​ 8. The battery cell of any one of claims 1 to 6, wherein, The binding layer (200) comprises a first binding layer (210) and a second binding layer (220), the first binding layer (210) is wound outside the winding layer (132) along the circumference of the electrode assembly (100), and the second binding layer (220) is wound outside the first binding layer (210) along the circumference of the electrode assembly (100).

9. The battery cell of any one of claims 1 to 6, wherein, The battery cell further comprises: A shell having a receiving cavity and an opening in communication with the receiving cavity, the electrode assembly (100) is arranged in the receiving cavity, and the binding layer (200) is in direct contact with the shell; A cover plate connected with the shell to close the opening, the cover plate is provided with a liquid injection hole in communication with the receiving cavity; A pole is provided on the cover plate and is electrically connected with the electrode assembly (100).

10. A battery pack, characterized by, The battery cell comprises any one of claims 1-9.

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