A battery cell, a battery pack, and an electrical device.

Abstract

This application discloses a battery cell, a battery pack, and an electrical device. The battery cell includes a positive electrode, a negative electrode, and a separator. The negative electrode, separator, and positive electrode are stacked and wound to form the battery cell, and the separator is disposed between the negative electrode and the positive electrode. The negative electrode active layer includes a reaction region and a redundant region, which are spaced apart along the length of the negative electrode. The surface of the negative electrode active layer in the reaction region that is away from the negative electrode current collector is covered with a positive electrode to allow the negative electrode active layer in the reaction region to exchange metal ions with the positive electrode active layer. The negative electrode active layer has a blocking groove between the reaction region and the redundant region, which is used to block at least some of the metal ions in the reaction region from migrating to the redundant region.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to a battery cell, a battery pack, and an electrical device. Background Technology

[0002] Lithium-ion batteries, with their advantages of light weight and high safety performance, have achieved a dominant position in the application of mobile electronic devices such as Bluetooth headsets, mobile phones, laptops, tablets, and cameras, as well as portable power banks. Simultaneously, lithium-ion batteries are also being used in large quantities in electric motorcycles and electric vehicles.

[0003] In related technologies, wound-structured battery cells typically consist of a positive electrode, a negative electrode, and a separator. The negative electrode area is usually larger than the positive electrode area, creating a redundant region. During the initial charging of the battery cell, lithium ions typically do not embed in the negative electrode active material of the redundant region, while lithium ions extracted from the corresponding positive electrode will embed in the non-redundant region. During long-term storage after charging, lithium ions in the non-redundant region of the negative electrode spontaneously migrate to the redundant region. This prevents the transferred lithium ions from being extracted from the negative electrode and returning to their corresponding positive electrode, ultimately leading to a loss of battery cell storage capacity. Utility Model Content

[0004] This application aims to provide a battery cell, battery pack, and electrical device that can solve the problem in the prior art where lithium ions in the non-redundant region of the negative electrode spontaneously transfer to the redundant region.

[0005] To solve the above-mentioned technical problems, this application is implemented as follows:

[0006] In a first aspect, embodiments of this application provide a battery cell, comprising: a positive electrode sheet, a negative electrode sheet, and a separator; the negative electrode sheet, the separator, and the positive electrode sheet are stacked and wound to form the battery cell, and the separator is disposed between the negative electrode sheet and the positive electrode sheet; the negative electrode sheet includes a negative current collector and a negative active layer, and the negative active layer is disposed on both sides of the negative current collector along the stacking direction of the positive electrode sheet and the negative electrode sheet; the positive electrode sheet includes a positive current collector and a positive active layer, and the positive electrode sheet includes a positive current collector and a positive active layer along the stacking direction of the positive electrode sheet and the negative electrode sheet. The positive electrode current collector has positive active layers on both sides of it; the negative electrode active layer includes a reaction region and a redundant region, the reaction region and the redundant region are spaced apart along the length of the negative electrode sheet, the surface of the negative electrode active layer in the reaction region that is away from the negative electrode current collector is covered by the positive electrode sheet, so that the negative electrode active layer in the reaction region and the positive electrode active layer can exchange metal ions, and the negative electrode active layer has a blocking groove between the reaction region and the redundant region, the blocking groove is used to block at least some of the metal ions in the reaction region from migrating to the redundant region.

[0007] Optionally, the blocking groove is formed by a partial recess from the surface of the negative electrode active layer on the side opposite to the negative electrode current collector, in the direction toward the negative electrode current collector.

[0008] Optionally, the blocking groove is recessed from the side surface of the negative electrode active layer away from the negative electrode current collector and extends through the negative electrode active layer towards the negative electrode current collector.

[0009] Optionally, a first filling layer is provided in the blocking groove.

[0010] Optionally, along the depth direction of the blocking groove, a second filling layer is further provided in the blocking groove, the second filling layer being located on the side of the first filling layer away from the negative electrode current collector.

[0011] Optionally, the sum of the thicknesses of the first filling layer and the second filling layer does not exceed the depth of the blocking groove.

[0012] Optionally, the negative electrode sheet has a width direction after being unfolded, and the blocking groove extends along the width direction. The extension trajectory of the blocking groove is one or more combinations of straight lines, curves, and broken lines.

[0013] Secondly, embodiments of this application propose a battery pack including the battery cells described in the above embodiments.

[0014] Thirdly, embodiments of this application propose an electrical device that includes the battery cell described in the above embodiments, or the battery pack described in the above embodiments.

[0015] In the embodiments of this application, a battery cell is formed by stacking and winding a negative electrode sheet, a separator, and a positive electrode sheet. The separator is disposed between the negative and positive electrode sheets. Negative active layers are provided on both sides of the negative current collector, and positive active layers are provided on both sides of the positive current collector. The negative active layer includes a reaction region and a redundant region. The surface of the negative active layer in the reaction region, facing away from the negative current collector, is covered with a positive electrode sheet to allow the negative active layer in the reaction region to exchange metal ions with the positive active layer. A blocking groove is provided between the negative active layer and the redundant region. In this way, metal ions are exchanged only between the reaction region and the corresponding positive active layer, avoiding the ineffective insertion of metal ions in the redundant region. The blocking groove physically isolates and disrupts the diffusion path of metal ions inside the negative active layer, preventing metal ions already inserted in the reaction region from migrating to the redundant region. That is, the insertion / extraction of metal ions is constrained within the corresponding range of the reaction region and the positive active layer. The blocking groove spatially severs the connection between the redundant region and the metal ion circulation system, thereby suppressing the capacity decay problem caused by the migration of metal ions to the redundant region. In summary, this application reduces cell storage capacity loss by setting a blocking groove between the reaction zone and the redundant zone, thereby blocking the migration of metal ions located in the reaction zone to the redundant zone.

[0016] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0017] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0018] Figure 1 This is a cross-sectional view of a battery cell in the existing technology;

[0019] Figure 2 This is a cross-sectional view of a battery cell according to an embodiment of this application;

[0020] Figure 3 This is a cross-sectional view of the negative electrode sheet according to an embodiment of this application;

[0021] Figure 4 This is a front view of a negative electrode sheet according to an embodiment of this application;

[0022] Figure 5 This is a front view of another negative electrode sheet according to an embodiment of this application.

[0023] Figure label:

[0024] 1-Separating membrane; 2-Positive electrode sheet; 21-Positive current collector; 22-Positive active layer; 3-Negative electrode sheet; 31-Negative current collector; 32-Negative active layer; 321-Redundant region; 322-Blocking groove; 323-Reaction region; 33-First filling layer; 34-Second filling layer; 4-Starting section; 5-Terminating section; 6-Intermediate section; X-First direction; Y-Second direction; Z-Third direction. Detailed Implementation

[0025] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated 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. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0026] The terms "first" and "second" in this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0027] 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.

[0028] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0029] like Figure 1As shown, a wound battery cell typically consists of a positive electrode, a negative electrode, and a separator. The innermost and outermost layers of the negative electrode wrap around the positive electrode, but the innermost and outermost negative electrode rings do not have corresponding positive electrode rings. The extra area of ​​the negative electrode rings forms a redundant region. This redundant region is designed to prevent metal ions released from the positive electrode during charging from failing to embed into the negative electrode, thus preventing lithium deposition on the negative electrode surface.

[0030] The existing battery cells do not have such features. Figure 2 The blocking groove 322 shown allows metal ions in the reaction region of the negative electrode to transfer to the redundant region. Thus, during the initial charging of the cell, the active material in the redundant region of the negative electrode typically does not have any metal ions embedded, while the non-redundant region will have metal ions embedded from the corresponding positive electrode. During long-term storage after charging, metal ions in the reaction region of the negative electrode will spontaneously transfer to the redundant region, preventing them from being released back into the corresponding positive electrode, ultimately leading to a loss of the cell's storage capacity.

[0031] The battery cells and battery packs provided in this application will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.

[0032] like Figure 2 As shown in the embodiment of this application, a battery cell is proposed, comprising: a positive electrode 2, a negative electrode 3, and a separator 1; the negative electrode 3, the separator 1, and the positive electrode 2 are stacked and wound to form the battery cell, and the separator 1 is disposed between the negative electrode 3 and the positive electrode 2; the negative electrode 3 includes a negative current collector 31 and a negative active layer 32, and along the stacking direction of the positive electrode 2 and the negative electrode 3, negative active layers 32 are disposed on opposite sides of the negative current collector 31; the positive electrode 2 includes a positive current collector 21 and a positive active layer 22, and along the stacking direction of the positive electrode 2 and the negative electrode 3, positive active layers 22 are disposed on opposite sides of the positive current collector 21. Each side is provided with a positive electrode active layer 22; the negative electrode active layer 32 includes a reaction region 323 and a redundant region 321. The reaction region 323 and the redundant region 321 are spaced apart along the length of the negative electrode plate 3. The surface of the negative electrode active layer 32 located in the reaction region 323 away from the negative electrode current collector 31 is covered with a positive electrode plate 2, so that the negative electrode active layer 32 in the reaction region 323 and the positive electrode active layer 22 exchange metal ions. The negative electrode active layer 32 is provided with a blocking groove 322 between the reaction region 323 and the redundant region 321. The blocking groove 322 is used to block at least some of the metal ions located in the reaction region 323 from migrating to the redundant region 321.

[0033] It should be noted that the stacking directions of the positive electrode 2 and the negative electrode 3 are as follows: Figure 1 In the first direction X, the length direction of the negative electrode plate 3 refers to the direction of the longer side of the unfolded negative electrode plate 3, that is... Figure 3 The second direction Y in the equation.

[0034] In the embodiments of this application, a battery cell is formed by stacking and winding a negative electrode 3, a separator 1, and a positive electrode 2. The separator 1 is disposed between the negative electrode 3 and the positive electrode 2. Negative active layers 32 are provided on both sides of the negative current collector 31, and positive active layers 22 are provided on both sides of the positive current collector 21. The negative active layer 32 includes a reaction region 323 and a redundant region 321. The reaction region 323 and the redundant region 321 are spaced apart along the length direction of the negative electrode 3. The surface of the negative active layer 32 in the reaction region 323 facing away from the negative current collector 31 is covered with the positive electrode 2, and the surface of the negative active layer 32 in the redundant region 321 facing away from the negative current collector 31 is not covered with the positive electrode 2, so that the negative active layer 32 in the reaction region 323 and the positive active layer 22 exchange metal ions. The negative active layer 32 has a blocking groove 322 between the reaction region 323 and the redundant region 321. In this way, metal ions are exchanged only between the reaction region 323 and the positive electrode active layer 22 corresponding to the reaction region 323, avoiding the transfer of metal ions from the reaction region 323 to the redundant region 321; that is, the insertion / extraction of metal ions is constrained within the corresponding range of the reaction region 323 and the positive electrode active layer 22, and the blocking groove 322 spatially severs the connection between at least part of the redundant region 321 and the metal ion circulation system, thereby suppressing the capacity decay problem caused by the migration of metal ions from the reaction region 323 to the redundant region 321.

[0035] In summary, this application reduces cell storage capacity loss by setting a blocking groove 322 between the reaction region 323 and the redundant region 321, thereby partially or completely blocking the migration of metal ions located in the reaction region 323 to the redundant region 321.

[0036] It should be noted that, as Figure 2 As shown, the surface of the negative electrode active layer 32 located in the reaction zone 323, facing away from the negative electrode current collector 31, is covered with a positive electrode plate 2, meaning that the negative electrode active layer 32 located in the reaction zone 323 has a corresponding positive electrode plate 2 for exchanging metal ions. Specifically, with Figure 2 Taking the innermost negative electrode 3 as an example, the innermost black redundant area 321 is located inside the negative current collector 31, and the outer side of the negative current collector 31 is provided with a reaction area 323 corresponding to the inner redundant area 321. This reaction area 323 is covered by a corresponding positive electrode 2; that is, the inner side of the innermost negative electrode 3 is the reaction area 323, and the outer side is the redundant area 321. The arrangement of the redundant area 321 and the reaction area 323 of the outermost negative electrode 3 is similar to that of the innermost negative electrode 3, and will not be described again in this embodiment.

[0037] Understandably, an electrolyte is also added to the battery cell. The positive current collector 21 and the negative current collector 31 can collect the current generated by the reaction between the electrolyte and the negative active layer 32 and the positive active layer 22 to form a larger current, thereby realizing the process of converting chemical energy into electrical energy. The positive current collector 21 and the negative current collector 31 act as carriers for the positive and negative active layers 22, respectively, and as carriers for collecting and transferring positive and negative electrons.

[0038] In some embodiments, the diaphragm may be configured as a porous structure to allow chemicals in the electrolyte to pass through.

[0039] Optionally, such as Figure 2 and Figure 3 As shown, along the winding direction of the battery cell, the negative electrode 3 includes a starting section 4, a ending section 5, and an intermediate section 6 located between the starting section 4 and the ending section 5. Both the starting section 4 and the ending section 5 are provided with a redundancy area 321, the intermediate section 6 is provided with a reaction area 323, and a blocking groove 322 is provided between the starting section 4 and the intermediate section 6, and / or, a blocking groove 322 is provided between the ending section 5 and the intermediate section 6.

[0040] In this embodiment, a blocking groove 322 is provided between the starting segment 4 and the middle segment 6, and another blocking groove 322 is provided between the ending segment 5 and the middle segment 6. This allows blocking grooves 322 to be provided at both ends of the negative electrode 3 along the second direction Y, so that the innermost and outermost rings of the negative electrode 3 are both located in the blocking grooves 322. This blocks the lateral migration path of metal ions from the edge region to the redundant region 321, suppresses the disordered diffusion of metal ions caused by local stress concentration during the charging and discharging process of the starting segment 4 / ending segment 5, and further improves the energy density of the battery cell.

[0041] It should be noted that, as Figure 2 and Figure 3 As shown, the initial segment 4 refers to the portion where the negative electrode 3 is wound for the first turn. In the initial segment 4, the negative electrode 3 facing the center of winding does not have a positive electrode 2, resulting in the negative electrode active layer 32 (i.e., ...) of the negative electrode 3 in the initial segment 4 on the side facing the center of winding. Figure 2 The portion shown by the bold black lines in the inner circle cannot react with the positive electrode 2, thus forming a... Figure 3 The redundant area 321 is shown; that is, the side of the starting segment 4 facing the winding center is the redundant area 321, the side of the starting segment 4 away from the winding center is the reaction area 323, and both sides of the middle segment 6 are reaction areas 323. Furthermore, a blocking groove 322 is provided between the redundant area 321 on the starting segment 4 and the reaction area 323 on the middle segment 6.

[0042] It should be noted that, as Figure 2 and Figure 3As shown, the termination section 5 refers to the part where the negative electrode 3 is wound for the last turn. In the termination section 5, the negative electrode 3 on the side away from the winding center does not have a positive electrode 2, resulting in a portion of the negative electrode active layer 32 (i.e., ...) on the side of the negative electrode 3 away from the winding center in the termination section 5. Figure 2 The portion shown by the thick black lines in the outer ring cannot react with the positive electrode 2, thus forming a... Figure 3 The redundant area 321 is shown; that is, the side of the termination segment 5 away from the winding center is the redundant area 321, the side of the termination segment 5 facing the winding center is the reaction area 323, and both sides of the middle segment 6 are reaction areas 323. Furthermore, an blocking groove 322 is provided between the redundant area 321 on the termination segment 5 and the reaction area 323 of the middle segment 6.

[0043] It is understandable that by severing the continuity between the winding end of the negative electrode sheet 3 and the negative electrode active layer 32 in the internal region, the metal ion exchange between the edge redundant region 321 and the positive electrode active layer 22 caused by the misalignment between the winding structure layers is eliminated due to unexpected circumstances, thereby solving the problem of metal ion edge escape easily at the end of the traditional wound cell.

[0044] In some embodiments, a control group and an experimental group can be set up to determine the impact of the blocking groove 322 on the improvement of the cell's energy density. Three experimental groups are set up, with the blocking grooves 322 in two groups respectively located in the starting segment 4 and the ending segment 5, and the blocking grooves 322 in the last experimental group located in both the starting segment 4 and the ending segment 5. It should be noted that the materials and electrode arrangement methods used in the control group and the experimental group are the same, and the settings of the control group and the experimental group are as follows:

[0045] Control group: such as Figure 1 The negative electrode 3, the separator 1, and the positive electrode 2 are stacked and wound to form a battery cell. The separator 1 is disposed between the negative electrode 3 and the positive electrode 2. The separator 1 separates the positive electrode 2 and the negative electrode 3, ensuring that the positive electrode 2 and the negative electrode 3 cannot directly contact each other. In addition, the negative active layer 32 of the negative electrode 3 covers the positive active layer 22 of the positive electrode 2 from the inner layer to the outer layer, ensuring that there is a corresponding negative active layer 32 on the positive active layer 22 of the positive electrode 2, thereby ensuring the normal charging and discharging of the battery cell.

[0046] Experimental Group 1: such as Figure 2 As shown, the blocking groove 322 is set in the starting section 4 and the ending section 5, thereby isolating the reaction region 323 and the redundant region 321 of the negative electrode active layer 32 located on both sides of the negative electrode plate 3.

[0047] Experimental Group 2: The blocking groove 322 is set in the starting section 4, thereby isolating the reaction region 323 and the redundant region 321 of the negative electrode active layer 32 located on one side of the negative electrode plate 3.

[0048] Experimental Group 3: The blocking groove 322 is set in the termination section 5, thereby isolating the reaction region 323 and the redundant region 321 of the negative electrode active layer 32 located on the other side of the negative electrode plate 3.

[0049] It should be noted that, in order to prevent the shape and size of the blocking groove 322 from affecting the storage capacity of the battery cell, the shape and size of the blocking groove 322 in experimental groups one to three are the same in this application.

[0050] The above experiments show that the cell storage capacity of experimental groups 1 to 3 was increased by 7% to 15% compared with the control group. Among them, the cell storage capacity of experimental group 1 was increased by 10% to 15% compared with the control group. The cell storage capacity of experimental groups 2 and 3 was similar, with both groups increasing by 7% to 10% compared with the control group.

[0051] Optionally, such as Figure 3 As shown, the blocking groove 322 is formed by a partial indentation on the side surface of the negative electrode active layer 32 that is away from the negative electrode current collector 31 and faces the negative electrode current collector 31.

[0052] In this embodiment, the blocking groove 322 is formed by partially recessing the surface of the negative electrode active layer 32 on the side facing away from the negative electrode current collector 31. This removes a portion of the negative electrode active layer 32 between the reaction zone 323 and the redundant zone 321 to form the blocking groove 322, thereby physically blocking the conduction of metal ions and cutting off the migration channel of metal ions in the plane direction of the negative electrode active layer 32. Without significantly altering the mechanical strength of the electrode, this method achieves partial blocking of the metal ion migration path while maintaining high compatibility with existing electrode processing technologies, effectively balancing the dual requirements of ion migration control and production feasibility.

[0053] It should be noted that the shape of the blocking groove 322 can be any shape, such as rectangular groove, circular groove, elliptical groove, polygonal groove, etc., as long as it can block the migration of metal ions from the reaction region 323 to the redundant region 321. Those skilled in the art can set it according to actual needs, and this application does not limit it.

[0054] Optionally, such as Figures 3 to 5 As shown, the blocking groove 322 is recessed from the side surface of the negative electrode active layer 32 away from the negative electrode current collector 31 and towards the negative electrode current collector 31 and penetrates the negative electrode active layer 32.

[0055] In the embodiment of the application, a blocking groove 322 is provided that penetrates through the negative electrode active layer 32. In this way, the blocking groove 322 is a through structure in the width direction of the negative electrode active layer 32, which eliminates the potential migration path of metal ions bypassing the blocking groove 322, and forms an isolation zone perpendicular to the diffusion direction of metal ions inside the negative electrode active layer 32, ensuring the physical separation between the reaction region 323 and the redundant region 321.

[0056] Optionally, such as Figure 3 As shown, a first filling layer 33 is provided inside the blocking groove 322.

[0057] In this embodiment, a first filling layer 33 is provided within the blocking groove 322. This first filling layer 33 supports the negative electrode active layer 32 surrounding the blocking groove 322, preventing the active material layer around the blocking groove 322 from detaching or moving into the groove during the winding process.

[0058] Optionally, such as Figure 3 As shown, along the depth direction of the blocking groove 322, i.e. Figure 2 In the first direction X, a second filling layer 34 is also provided in the blocking groove 322. The second filling layer 34 is located on the side of the first filling layer 33 away from the negative electrode current collector 31.

[0059] In this embodiment, a second filling layer 34 is provided within the blocking groove 322, and the second filling layer 34 is located on the side of the first filling layer 33 away from the negative electrode current collector 31. Thus, the cooperation of the second filling layer 34 and the first filling layer 33 enhances the limiting and supporting effect on the negative electrode active layer 32 around the opening of the blocking groove 322. Simultaneously, it allows for flexible selection of the materials of the two filling layers to meet different performance requirements.

[0060] Specifically, the first filling layer 33 can be an insulating adhesive layer, and the second filling layer 34 can be foam. The insulating adhesive layer can further insulate the reaction zone 323 and the redundant zone 321, providing an insulating effect and preventing metal ions in the reaction zone 323 from transferring towards the redundant zone 321; the foam can support the two side walls of the blocking groove 322, preventing the blocking groove 322 from collapsing so that the reaction zone 323 and the redundant zone 321 can come into contact.

[0061] For example, the insulating adhesive layer can be silicone rubber, ethylene propylene rubber, polyvinyl chloride, and cross-linked polyethylene, etc.; the foam can be polyurethane foam, polyethylene foam, and rubber foam, etc. Of course, the second filler layer and the first filler layer 33 can also be made of other materials, and this application embodiment does not limit this.

[0062] Optionally, such as Figure 3 As shown, the sum of the thicknesses of the first filling layer 33 and the second filling layer 34 does not exceed the depth of the blocking groove 322.

[0063] In this embodiment, the sum of the thicknesses of the first filling layer 33 and the second filling layer 34 is set to not exceed the depth of the blocking groove 322. This ensures that the first filling layer 33 and the second filling layer 34 disposed in the blocking groove 322 do not protrude from the surface of the negative electrode active layer 32, thereby avoiding localized attraction concentration at the blocking groove 322 that could lead to deformation and damage to the separator 1.

[0064] Optionally, such as Figure 3 As shown, the positive electrode 2 and the negative electrode 3 are stacked in the first direction X. The depth of the blocking groove 322 along the first direction X is H1, and the thickness of the negative electrode active layer 32 along the first direction X is H2, satisfying: 0.5≤H1 / H2≤1.

[0065] In this embodiment, H1 / H2 is set within a certain range. This avoids situations where the value of H1 / H2 is too small, resulting in poor blocking effect of metal ions from the reaction zone 323 to the redundant zone 321, and also avoids the risk of electrode delamination caused by excessively deep blocking grooves 322. In other words, by limiting the parameter range, a balance is maintained between ion migration control, structural stability, and production process.

[0066] For example, the value of H1 / H2 can be set to any value among 0.5, 0.6, 0.7, 0.8, 0.9, and 1, or a range between any two values.

[0067] In some embodiments, when the value of H1 / H2 is 1, that is, the bottom of the blocking groove 322 is the negative electrode current collector 31. In this way, taking advantage of the characteristic that the negative electrode current collector 31 does not participate in the metal ion transport, a secondary blocking node is formed at the interface between the negative electrode active layer 32 and the negative electrode current collector 31, thereby further blocking the migration of metal ions from the reaction zone 323 to the redundant zone 321.

[0068] Furthermore, when the value of H1 / H2 is 0.5 ≤ H1 / H2 < 1, that is, the bottom of the blocking groove 322 is located in the negative electrode active layer 32. In this way, the reaction region 323 and the redundant region 321 are partially isolated, thereby preventing some metal ions in the reaction region 323 from migrating to the redundant region 321.

[0069] Optionally, the length direction of the unfolded negative electrode 3 is the second direction Y; the dimension of the blocking groove 322 along the second direction Y is W, which satisfies: 0.1mm≤W≤8.0mm.

[0070] In the embodiment of the application, the dimension W of the blocking groove 322 along the second direction Y is set within a certain range. This ensures, on the one hand, that the width of the blocking groove 322 is sufficient to form an effective metal ion diffusion barrier, avoiding blocking failure due to processing accuracy errors, while also preventing the risk of electrode breakage caused by stress concentration due to an excessively narrow blocking groove 322; on the other hand, it limits the proportion of the blocking groove 322 occupying the effective reaction region 323 of the negative electrode active layer 32, achieving a balance between blocking efficiency and active material utilization, and preventing an excessively wide blocking groove 322 from weakening the continuity of the conductive network of the negative electrode 3 and causing capacity loss.

[0071] For example, the value of W can be set to any value among 0.1mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, and 8mm, or a range between any two values.

[0072] Optionally, such as Figure 3 As shown, the length of the redundant region 321 along the second direction Y is L1, and the total length of the negative electrode active layer 32 along the second direction Y is L2, satisfying: 0.03≤(L1+W) / L2≤0.5.

[0073] In the embodiment of the application, the length of the redundant region 321 along the second direction Y is set to L1, and the total length of the negative electrode active layer 32 along the second direction Y is set to L2, with (L1+W) / L2 within a certain range. This ensures that the redundant region 321 has sufficient metal ion buffer space, while the width of the blocking groove 322 meets the minimum effective blocking requirement, preventing blocking failure or insufficient function of the redundant region 321 due to excessively low proportion. In addition, the total length of the non-reactive region 323 is controlled within 50% of the total length of the negative electrode active layer 32, avoiding excessive sacrifice of the area of ​​the reactive region 323, and maintaining the effective reaction area of ​​the negative electrode active layer 32 while suppressing irreversible migration of metal ions.

[0074] In addition, by superimposing control of L1 and W, the blocking effect of the blocking groove 322 and the spatial compensation of the redundant area 321 form a linkage mechanism. The increase of the width W of the blocking groove 322 can correspond to the need to reduce the length L1 of the redundant area 321. Under the premise of maintaining the same blocking performance, the flexible design of the electrode structure can be realized to adapt to different winding curvatures or assembly tolerance requirements.

[0075] For example, the value of (L1+W) / L2 can be set to any value among 0.03, 0.1, 0.2, 0.3, 0.4, and 0.5, or a range between any two values.

[0076] Optionally, along the second direction Y, the distance from the blocking groove 322 to the edge of the positive electrode 2 adjacent to the blocking groove 322 is L3, satisfying: 0≤L3≤10mm.

[0077] In the embodiment of the application, the distance L3 between the blocking groove 322 and the edge of the positive electrode 2 adjacent to the blocking groove 322 is set within a certain range. In this way, when the edge of the blocking groove 322 is completely aligned with the edge of the positive electrode 2, a synergistic effect of the projection coverage of the positive active layer 22 and the blocking effect of the blocking groove 322 is formed, ensuring that metal ions can only be inserted / extracted in the reaction area 323 corresponding to the positive electrode coverage area, eliminating the risk of "lateral leakage" of metal ions caused by edge misalignment; in addition, a moderate offset between the blocking groove 322 and the edge of the positive electrode 2 is allowed. Through the superposition of the blocking width and spacing of the blocking groove 322, the maximum possible offset area of ​​the positive electrode 2 can still be covered within the manufacturing assembly tolerance range, preventing the edge of the positive active layer 22 from exceeding the blocking range of the blocking groove 322 when the winding is misaligned.

[0078] In addition, when L3>0, a mechanical buffer zone is formed in the region of the negative electrode active layer 32 between the blocking groove 322 and the edge of the positive electrode 2. The stress release effect of the blocking groove 322 reduces the risk of microcrack propagation caused by the winding tension in the overlapping area at the edge of the negative electrode 3, thereby improving the stability of the electrode interface.

[0079] For example, the value of L3 can be set to any value among 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, and 10mm, or a range between any two values.

[0080] Optionally, such as Figure 4 and Figure 5 As shown, the width direction of the unfolded negative electrode sheet is the third direction Z, and the blocking groove 322 extends along the third direction Z. The extension trajectory of the blocking groove 322 is one or more combinations of straight line, curve and broken line.

[0081] In the embodiments of the application, the extension trajectory of the blocking groove 322 is set to be one or more combinations of straight lines, curves, and broken lines. In this way, through topology optimization of multiple trajectory shapes, the blocking groove 322 has both rigid blocking and flexible adaptation characteristics, forming a multi-dimensional synergy between metal ion migration suppression, electrode mechanical stability, and manufacturing process feasibility, thereby comprehensively improving the cycle life and environmental adaptability of the battery cell.

[0082] Specifically, the blocking groove 322 with a straight trajectory can form a continuous blocking band with the shortest path, which is suitable for areas with uniform winding tension and achieves efficient lateral ion migration interception with minimal processing cost; the blocking groove 322 with a curved trajectory extends the lateral diffusion distance of metal ions through a detour path, adapts to areas with varying winding curvature, and uses the radius of curvature to disperse mechanical stress; the blocking groove 322 with a broken line trajectory forms an ion migration reflection interface in multiple directions, blocking oblique diffusion at different angles, and is suitable for three-dimensional protection of electrode edges.

[0083] It should be noted that the blocking groove 322 with a straight trajectory can be processed by high-precision rolling or die-cutting to ensure processing consistency; the blocking groove 322 with a curved / zigzag trajectory can be processed by laser etching or 3D printing to achieve complex patterning, meeting the needs of customized cell design; the combined trajectory supports a regional processing strategy, using complex trajectories with high blocking efficiency in critical areas (such as the upper and lower ends of the negative electrode sheet along the third direction Z), and using simple trajectories in non-critical areas to reduce costs.

[0084] Optionally, embodiments of this application propose a battery pack including the battery cells described in the above embodiments.

[0085] In the embodiments of this application, a battery cell is formed by stacking and winding a negative electrode 3, a separator 1, and a positive electrode 2. The separator 1 is disposed between the negative electrode 3 and the positive electrode 2. Negative active layers 32 are provided on both sides of the negative current collector 31, and positive active layers 22 are provided on both sides of the positive current collector 21. The negative active layer 32 includes a reaction region 323 and a redundant region 321. The reaction region 323 and the redundant region 321 are spaced apart along the length direction of the negative electrode 3. The surface of the negative active layer 32 in the reaction region 323 facing away from the negative current collector 31 is covered with the positive electrode 2, and the surface of the negative active layer 32 in the redundant region 321 facing away from the negative current collector 31 is not covered with the positive electrode 2, so that the negative active layer 32 in the reaction region 323 and the positive active layer 22 exchange metal ions. The negative active layer 32 has a blocking groove 322 between the reaction region 323 and the redundant region 321. In this way, metal ions are exchanged only between the reaction region 323 and the positive electrode active layer 22 corresponding to the reaction region 323, avoiding the transfer of metal ions from the reaction region 323 to the redundant region 321; that is, the insertion / extraction of metal ions is constrained within the corresponding range of the reaction region 323 and the positive electrode active layer 22, and the blocking groove 322 spatially severs the connection between at least part of the redundant region 321 and the metal ion circulation system, thereby suppressing the capacity decay problem caused by the migration of metal ions from the reaction region 323 to the redundant region 321.

[0086] In summary, this application reduces cell storage capacity loss by setting a blocking groove 322 between the reaction region 323 and the redundant region 321 to block the migration of metal ions located in the reaction region 323 to the redundant region 321.

[0087] In specific applications, the battery pack can be at least one of lithium-ion battery packs, solid-state battery packs, lead-acid battery packs, and nickel-metal hydride battery packs. Those skilled in the art can choose according to actual needs, and this application does not impose any restrictions on this.

[0088] Optionally, embodiments of this application also propose a battery pack, including the battery cells described in the above embodiments, or including the battery pack described in the above embodiments.

[0089] In the embodiments of this application, a battery cell is formed by stacking and winding a negative electrode 3, a separator 1, and a positive electrode 2. The separator 1 is disposed between the negative electrode 3 and the positive electrode 2. Negative active layers 32 are provided on both sides of the negative current collector 31, and positive active layers 22 are provided on both sides of the positive current collector 21. The negative active layer 32 includes a reaction region 323 and a redundant region 321. The reaction region 323 and the redundant region 321 are spaced apart along the length direction of the negative electrode 3. The surface of the negative active layer 32 in the reaction region 323 facing away from the negative current collector 31 is covered with the positive electrode 2, and the surface of the negative active layer 32 in the redundant region 321 facing away from the negative current collector 31 is not covered with the positive electrode 2, so that the negative active layer 32 in the reaction region 323 and the positive active layer 22 exchange metal ions. The negative active layer 32 has a blocking groove 322 between the reaction region 323 and the redundant region 321. In this way, metal ions are exchanged only between the reaction region 323 and the positive electrode active layer 22 corresponding to the reaction region 323, avoiding the transfer of metal ions from the reaction region 323 to the redundant region 321; that is, the insertion / extraction of metal ions is constrained within the corresponding range of the reaction region 323 and the positive electrode active layer 22, and the blocking groove 322 spatially severs the connection between at least part of the redundant region 321 and the metal ion circulation system, thereby suppressing the capacity decay problem caused by the migration of metal ions from the reaction region 323 to the redundant region 321.

[0090] In summary, this application reduces cell storage capacity loss by setting a blocking groove 322 between the reaction region 323 and the redundant region 321 to block the migration of metal ions located in the reaction region 323 to the redundant region 321.

[0091] In some embodiments, electrical devices may include laptops, pen-based computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, bicycles, ships, spacecraft, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, and lithium-ion capacitors, etc.

[0092] Specifically, the vehicle can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc.

[0093] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is 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.

[0094] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A battery cell, characterized in that, include: Positive electrode (2), negative electrode (3), and separator (1); The negative electrode (3), the separator (1) and the positive electrode (2) are stacked and wound to form the battery cell, and the separator (1) is disposed between the negative electrode (3) and the positive electrode (2); The negative electrode (3) includes a negative current collector (31) and a negative active layer (32). Along the stacking direction of the positive electrode (2) and the negative electrode (3), the negative active layer (32) is provided on both sides of the negative current collector (31). The positive electrode (2) includes a positive current collector (21) and a positive active layer (22). Along the stacking direction of the positive electrode (2) and the negative electrode (3), the positive active layer (22) is provided on both sides of the positive current collector (21). The negative electrode active layer (32) includes a reaction region (323) and a redundant region (321). The reaction region (323) and the redundant region (321) are spaced apart along the length of the negative electrode sheet (3). The surface of the negative electrode active layer (32) in the reaction region (323) facing away from the negative electrode current collector (31) is covered with the positive electrode sheet (2) so that the negative electrode active layer (32) in the reaction region (323) exchanges metal ions with the positive electrode active layer (22). The negative electrode active layer (32) has a blocking groove (322) between the reaction region (323) and the redundant region (321). The blocking groove (322) is used to block at least some of the metal ions located in the reaction region (323) from migrating to the redundant region (321).

2. The battery cell according to claim 1, characterized in that, The blocking groove (322) is partially recessed from the side surface of the negative electrode active layer (32) away from the negative electrode current collector (31) and towards the negative electrode current collector (31).

3. The battery cell according to claim 1, characterized in that, The blocking groove (322) is recessed from the side surface of the negative electrode active layer (32) away from the negative electrode current collector (31) and extends through the negative electrode active layer (32).

4. The battery cell according to claim 2 or 3, characterized in that, The blocking groove (322) is provided with a first filling layer (33).

5. The battery cell according to claim 4, characterized in that, Along the depth direction of the blocking groove (322), a second filling layer (34) is also provided in the blocking groove (322), and the second filling layer (34) is located on the side of the first filling layer (33) away from the negative electrode current collector (31).

6. The battery cell according to claim 5, characterized in that, The first filling layer (33) is an insulating adhesive layer, and the second filling layer (34) is foam.

7. The battery cell according to claim 5, characterized in that, The sum of the thicknesses of the first filling layer (33) and the second filling layer (34) does not exceed the depth of the blocking groove (322).

8. The battery cell according to claim 1, characterized in that, The negative electrode sheet (3) has a width direction after being unfolded, and the blocking groove (322) extends along the width direction. The extension trajectory of the blocking groove (322) is one or more combinations of straight line, curve and broken line.

9. A battery pack, characterized in that, Includes the battery cell according to any one of claims 1-8.

10. An electrical appliance, characterized in that, It includes the battery cell according to any one of claims 1-8, or the battery pack according to claim 9.

Images