Electrode assembly and manufacturing method therefor, battery cell, battery device, and electric device

Abstract

Provided are an electrode assembly and a manufacturing method therefor, a battery cell, a battery device, and an electric device. The battery cell comprises the electrode assembly, and the electrode assembly comprises negative electrode sheets, separators, and positive electrode sheets which are stacked. Each negative electrode sheet comprises a negative tab unit and a negative electrode sheet body. The negative tab unit is connected to one side of the negative electrode sheet body, and the thickness of the negative electrode sheet body ranges from 10 μm to 30 μm. Each separator has a separation section separating the corresponding positive electrode sheet from the corresponding negative electrode sheet. The separation section has first extended portions extending beyond the positive electrode sheet on both sides in a first direction, and the first extended portions of two isolation sections adjacent to the positive electrode sheet are at least partially fixedly connected. The first direction is perpendicular to the stacking direction. By at least partially fixedly connecting the first extended portions of the two isolation sections adjacent to the positive electrode sheet, the position of the positive electrode sheet is limited to facilitate the extension of the negative electrode sheet beyond the positive electrode sheet in the first direction and reduce the risk of lithium precipitation, and dendrites are prevented from growing in a bypass manner to reduce the risk of short circuit, thereby improving the reliability of the battery cell.

Description

Electrode assemblies and their manufacturing methods, battery cells, battery devices and electrical devices Technical Field

[0001] This application relates to the field of batteries, and more specifically, to an electrode assembly and its manufacturing method, a battery cell, a battery device, and an electrical device. Background Technology

[0002] Batteries are widely used in the new energy field, such as in electric vehicles and new energy vehicles, which have become a new trend in the automotive industry. The development of battery technology must consider multiple design factors simultaneously, such as energy density, cycle life, discharge capacity, and charge / discharge rate. Additionally, battery reliability must also be considered. However, current battery reliability is relatively poor.

[0003] Summary of the Invention

[0004] The purpose of this application is to provide an electrode assembly and its manufacturing method, a battery cell, a battery device, and an electrical device, which aim to improve the problem of poor battery reliability in related technologies.

[0005] In a first aspect, embodiments of this application provide a battery cell, the battery cell including a housing and an electrode assembly, the electrode assembly being housed within the housing, the electrode assembly including a negative electrode, a separator, and a positive electrode, the positive electrode, the separator, and the negative electrode being stacked, the negative electrode including a negative electrode tab unit and a negative electrode body, the negative electrode tab unit being connected to one side of the negative electrode body, the thickness of the negative electrode body being 10μm to 30μm; the separator having a separating segment separating the positive electrode and the negative electrode, the separating segment having a first extended portion extending beyond the positive electrode on both sides in a first direction, the first extended portions of two adjacent separating segments being at least partially fixedly connected to cover at least a portion of the edge of the positive electrode, the first direction being perpendicular to the stacking direction of the positive electrode, the separator, and the negative electrode.

[0006] In the above technical solution, the thickness of the negative electrode body of the battery cell is 10μm to 30μm, that is, the negative electrode is an ultra-thin negative electrode. The negative electrode is relatively soft, and it is not easy for the negative electrode to extend beyond the positive electrode in the first direction during stacking. By fixing at least part of the first protruding portion of the two isolation sections adjacent to the positive electrode to cover at least part of the edge of the positive electrode, on the one hand, the position of the positive electrode can be limited, thereby facilitating the negative electrode to extend beyond the positive electrode in the first direction and reducing the risk of lithium plating. On the other hand, it can prevent dendrite growth around the positive electrode, thereby reducing the risk of short circuit and improving the reliability of the battery cell.

[0007] As an optional technical solution in this application embodiment, the thickness of the negative electrode body is 10μm to 20μm.

[0008] In the above technical solution, the negative electrode body is thinner and the negative electrode is softer. By fixing at least part of the first extended portion of the two isolation sections adjacent to the positive electrode to cover at least part of the edge of the positive electrode, a better effect can be achieved.

[0009] As an optional technical solution in this application embodiment, the negative electrode body includes a negative electrode current collector, the material of which includes aluminum; the positive electrode includes a positive electrode active material capable of reversibly extracting and inserting sodium ions, the positive electrode active material including a sodium-containing compound.

[0010] In the above technical solution, the material of the negative electrode current collector includes aluminum, the negative electrode sheet is softer, and better performance can be achieved by fixing at least part of the first extended portion of the two isolation sections adjacent to the positive electrode sheet to cover at least part of the edge of the positive electrode sheet.

[0011] As an optional technical solution in this application embodiment, the electrode assembly includes a plurality of negative electrode sheets and a plurality of positive electrode sheets. Along the stacking direction, the plurality of negative electrode sheets are spaced apart, and the positive electrode sheet is disposed between two adjacent negative electrode sheets. The isolation section separates the positive electrode sheet and the negative electrode sheet.

[0012] In the above technical solution, multiple negative electrode sheets and multiple positive electrode sheets are stacked, with an isolation section separating the positive and negative electrode sheets. This eliminates the bending area of ​​the negative electrode sheet, which helps reduce volume and increase energy density. During manufacturing, a large negative electrode sheet can be continuously bent and stacked, and then cut to form multiple negative electrode sheets.

[0013] As an optional technical solution in this application embodiment, the negative electrode sheet has a first edge along the first direction, and the distance between the first edges of two adjacent negative electrode sheets is L1, which satisfies: 0≤L1≤2mm.

[0014] In the above technical solution, by making the gap between the first edges of two adjacent negative electrode sheets less than or equal to 2mm, the first edges of multiple negative electrode sheets of the electrode assembly can be made more uniform, which is beneficial to reduce volume occupation and improve energy density.

[0015] As an optional technical solution in this application embodiment, 0≤L1≤1mm.

[0016] In the above technical solution, by making the gap between the first edges of two adjacent negative electrode sheets less than or equal to 1 mm, the first edges of multiple negative electrode sheets of the electrode assembly can be made more uniform, which is beneficial to reduce volume occupation and improve energy density.

[0017] As an optional technical solution in this application embodiment, along the first direction, the negative electrode sheet has a first edge, and the isolation segment adjacent to the negative electrode sheet has a second edge that is closest to the first edge. The distance between the first edge and the second edge is L2, which satisfies: 0≤L2≤2mm.

[0018] In the above technical solution, by making the distance between the first edge and the second edge less than or equal to 2mm, the edges of the negative electrode and the isolation section can be made more neat, which is beneficial to reduce volume occupation and improve energy density.

[0019] As an optional technical solution in this application embodiment, 0≤L2≤1mm.

[0020] In the above technical solution, by making the distance between the first edge and the second edge less than or equal to 1mm, the edges of the negative electrode and the isolation section can be made neater, which is beneficial to reduce volume occupation and improve energy density.

[0021] As an optional technical solution in this application embodiment, along the first direction, the negative electrode body extends beyond the positive electrode by a dimension L3, satisfying: 3mm≤L3≤10mm.

[0022] In the above technical solution, when L3 ≥ 3mm, the negative electrode body extends significantly beyond the positive electrode along the first direction, which is beneficial for meeting the overhang design and reducing the risk of lithium plating. When L3 ≤ 10mm, the negative electrode body does not extend excessively beyond the positive electrode along the first direction, which is beneficial for reducing the volume of the negative electrode and increasing energy density. Therefore, when 3mm ≤ L3 ≤ 10mm, both the overhang design and energy density can be improved.

[0023] As an optional technical solution in this application embodiment, 5mm≤L3≤8mm.

[0024] In the above technical solution, when L3 ≥ 5mm, the negative electrode body extends further beyond the positive electrode along the first direction, which is more conducive to meeting the overhang design and reducing the risk of lithium plating. When L3 ≤ 8mm, the negative electrode body extends slightly beyond the positive electrode along the first direction, which helps to reduce the volume of the negative electrode and improve energy density. Therefore, when 5mm ≤ L3 ≤ 8mm, both the overhang design and energy density can be improved.

[0025] As an optional technical solution in this application embodiment, the positive electrode includes a positive electrode tab unit and a positive electrode body. The positive electrode tab unit is connected to one side of the positive electrode body along a second direction. The isolation segment has a second overhang portion extending beyond the positive electrode body on both sides of the second direction. The second overhang portions of two isolation segments adjacent to the positive electrode body are at least partially fixedly connected to cover at least a portion of the edge of the positive electrode body. The first direction, the second direction, and the stacking direction are perpendicular to each other.

[0026] In the above technical solution, by fixing at least a portion of the second extension of the two isolation sections adjacent to the positive electrode body to cover at least a portion of the edge of the positive electrode body, the position of the positive electrode can be limited, thereby facilitating the negative electrode to extend beyond the positive electrode in the first direction and reducing the risk of lithium plating. On the other hand, it can prevent dendrite growth, thereby reducing the risk of short circuit and improving the reliability of the battery cell.

[0027] As an optional technical solution in this application embodiment, the two isolation sections adjacent to the positive electrode are connected to form a closed receiving space, and the positive electrode body is received in the receiving space.

[0028] In the above technical solution, by accommodating the positive electrode body within the accommodating space, the position of the positive electrode body can be limited, thereby facilitating the negative electrode to extend beyond the positive electrode along the first direction and reducing the risk of lithium plating. Furthermore, it can further prevent dendrite growth, thereby reducing the risk of short circuits and improving the reliability of the battery cell.

[0029] Secondly, embodiments of this application also provide an electrode assembly, the electrode assembly including a negative electrode sheet, an isolator and a positive electrode sheet, the positive electrode sheet, the isolator and the negative electrode sheet being stacked, the negative electrode sheet including a negative electrode tab unit and a negative electrode sheet body, the negative electrode tab unit being connected to one side of the negative electrode sheet body, the thickness of the negative electrode sheet body being 10μm to 30μm; the isolator having an isolation segment separating the positive electrode sheet and the negative electrode sheet, the isolation segment having a first extended portion extending beyond the positive electrode sheet on both sides in a first direction, the first extended portions of two isolation segments adjacent to the positive electrode sheet being at least partially fixedly connected to cover at least a portion of the edge of the positive electrode sheet, the first direction being perpendicular to the stacking direction of the positive electrode sheet, the isolator and the negative electrode sheet.

[0030] As an optional technical solution in this application embodiment, the thickness of the negative electrode body is 10μm to 20μm.

[0031] In the above technical solution, the negative electrode body is thinner and the negative electrode is softer. By fixing at least part of the first extended portion of the two isolation sections adjacent to the positive electrode to cover at least part of the edge of the positive electrode, a better effect can be achieved.

[0032] As an optional technical solution in this application embodiment, the negative electrode body includes a negative electrode current collector, the material of which includes aluminum; the positive electrode includes a positive electrode active material capable of reversibly extracting and inserting sodium ions, the positive electrode active material including a sodium-containing compound.

[0033] In the above technical solution, the material of the negative electrode current collector includes aluminum, the negative electrode sheet is softer, and better performance can be achieved by fixing at least part of the first extended portion of the two isolation sections adjacent to the positive electrode sheet to cover at least part of the edge of the positive electrode sheet.

[0034] As an optional technical solution in this application embodiment, the electrode assembly includes a plurality of negative electrode sheets and a plurality of positive electrode sheets. Along the stacking direction, the plurality of negative electrode sheets are spaced apart, and the positive electrode sheet is disposed between two adjacent negative electrode sheets. The isolation section separates the positive electrode sheet and the negative electrode sheet.

[0035] In the above technical solution, multiple negative electrode sheets and multiple positive electrode sheets are stacked, with an isolation section separating the positive and negative electrode sheets. This eliminates the bending area of ​​the negative electrode sheet, which helps reduce volume and increase energy density. During manufacturing, a large negative electrode sheet can be continuously bent and stacked, and then cut to form multiple negative electrode sheets.

[0036] As an optional technical solution in this application embodiment, the negative electrode sheet has a first edge along the first direction, and the distance between the first edges of two adjacent negative electrode sheets is L1, which satisfies: 0≤L1≤2mm.

[0037] In the above technical solution, by making the gap between the first edges of two adjacent negative electrode sheets less than or equal to 2mm, the first edges of multiple negative electrode sheets of the electrode assembly can be made more uniform, which is beneficial to reduce volume occupation and improve energy density.

[0038] As an optional technical solution in this application embodiment, 0≤L1≤1mm.

[0039] In the above technical solution, by making the gap between the first edges of two adjacent negative electrode sheets less than or equal to 1 mm, the first edges of multiple negative electrode sheets of the electrode assembly can be made more uniform, which is beneficial to reduce volume occupation and improve energy density.

[0040] As an optional technical solution in this application embodiment, along the first direction, the negative electrode sheet has a first edge, and the isolation segment adjacent to the negative electrode sheet has a second edge that is closest to the first edge. The distance between the first edge and the second edge is L2, which satisfies: 0≤L2≤2mm.

[0041] In the above technical solution, by making the distance between the first edge and the second edge less than or equal to 2mm, the edges of the negative electrode and the isolation section can be made more neat, which is beneficial to reduce volume occupation and improve energy density.

[0042] As an optional technical solution in this application embodiment, 0≤L2≤1mm.

[0043] In the above technical solution, by making the distance between the first edge and the second edge less than or equal to 1mm, the edges of the negative electrode and the isolation section can be made neater, which is beneficial to reduce volume occupation and improve energy density.

[0044] As an optional technical solution in this application embodiment, along the first direction, the negative electrode body extends beyond the positive electrode by a dimension L3, satisfying: 3mm≤L3≤10mm.

[0045] In the above technical solution, when L3 ≥ 3mm, the negative electrode body extends significantly beyond the positive electrode along the first direction, which is beneficial for meeting the overhang design and reducing the risk of lithium plating. When L3 ≤ 10mm, the negative electrode body does not extend excessively beyond the positive electrode along the first direction, which is beneficial for reducing the volume of the negative electrode and increasing energy density. Therefore, when 3mm ≤ L3 ≤ 10mm, both the overhang design and energy density can be improved.

[0046] As an optional technical solution in this application embodiment, 5mm≤L3≤8mm.

[0047] In the above technical solution, when L3 ≥ 5mm, the negative electrode body extends further beyond the positive electrode along the first direction, which is more conducive to meeting the overhang design and reducing the risk of lithium plating. When L3 ≤ 8mm, the negative electrode body extends slightly beyond the positive electrode along the first direction, which helps to reduce the volume of the negative electrode and improve energy density. Therefore, when 5mm ≤ L3 ≤ 8mm, both the overhang design and energy density can be improved.

[0048] Thirdly, embodiments of this application also provide an electrode assembly manufacturing method, the electrode assembly manufacturing method comprising: step S100: providing a positive electrode sheet, an isolator and a negative electrode sheet, the negative electrode sheet comprising a negative electrode tab unit and a negative electrode sheet body, the negative electrode tab unit being connected to one side of the negative electrode sheet body, the thickness of the negative electrode sheet body being 10μm to 30μm; step S200: stacking the positive electrode sheet, the isolator and the negative electrode sheet, the isolator having an isolating segment separating the positive electrode sheet and the negative electrode sheet, the isolating segment having a first extending portion extending beyond the positive electrode sheet on both sides in a first direction, the first direction being perpendicular to the stacking direction of the positive electrode sheet, the isolator and the negative electrode sheet; step S300: at least partially fixing the first extending portions of two isolating segments adjacent to the positive electrode sheet to cover at least a portion of the edge of the positive electrode sheet.

[0049] As an optional technical solution in this application embodiment, in step S100, the thickness of the negative electrode body is 10μm to 20μm.

[0050] In the above technical solution, the negative electrode body is thinner and the negative electrode is softer. By fixing at least part of the first extended portion of the two isolation sections adjacent to the positive electrode to cover at least part of the edge of the positive electrode, a better effect can be achieved.

[0051] As an optional technical solution in this application embodiment, in step S200, the difference between the maximum thickness of the negative electrode body and the minimum thickness of the negative electrode is less than or equal to 2μm.

[0052] In the above technical solution, the difference between the maximum thickness of the negative electrode body and the minimum thickness of the negative electrode is less than or equal to 2μm, that is, the thickness of the negative electrode body at various locations is roughly the same. In other words, there is no need to make marks on the negative electrode body.

[0053] As an optional technical solution in this application embodiment, the thickness of the negative electrode body is equal at all positions.

[0054] In the above technical solution, the thickness of the negative electrode body is equal at all locations, so there is no need to make marks on the negative electrode body.

[0055] As an optional technical solution in an embodiment of this application, step S200 includes: step S210: forming the positive electrode, the separator, and the negative electrode into a composite electrode, the composite electrode including multiple positive electrode pieces, the multiple positive electrode pieces being alternately disposed on both sides of the negative electrode, and the portion of the composite electrode located between two adjacent positive electrode pieces along the length direction of the composite electrode being a bent section; step S220: bending the bent section so that the positive electrode, the separator, and the negative electrode are stacked.

[0056] In the above technical solution, by first making a composite electrode sheet, the bending section of the composite electrode sheet is relatively weak, and the bending section can be bent to stack the positive electrode sheet, the separator and the negative electrode sheet, which makes the manufacturing simple and convenient, and also helps to make the negative electrode sheet extend beyond the positive electrode sheet along the first direction, reducing the risk of lithium plating.

[0057] As an optional technical solution in this application embodiment, after step S300, the electrode assembly manufacturing method further includes: step S400: cutting the negative electrode sheet and the separator to remove the portion of the negative electrode sheet and the separator located in the bent section of the composite electrode sheet.

[0058] In the above technical solution, because the negative electrode is relatively soft, the bending section of the composite electrode is prone to a large curvature. By cutting the negative electrode and the separator, the portions of the negative electrode and the separator located in the bending section of the composite electrode are removed, thus shaping the electrode assembly. On the one hand, this helps to make the interface of the electrode assembly flat, resulting in a smaller gap between the positive and negative electrodes, which helps to shorten the ion path. On the other hand, it helps to reduce the volume occupation and increase the energy density.

[0059] As an optional technical solution in this application embodiment, in step S400, the negative electrode sheet has a first edge along the first direction, and the distance between the first edges of two adjacent negative electrode sheets is controlled within 2mm.

[0060] In the above technical solution, by making the gap between the first edges of two adjacent negative electrode plates less than or equal to 2 mm, the cutting surface is made neater. On the one hand, this results in a smaller gap between the positive and negative electrode plates, which helps to shorten the ion path. On the other hand, it helps to reduce the volume occupied and increase the energy density.

[0061] As an optional technical solution in this application embodiment, in step S400, the negative electrode sheet has a first edge along the first direction, and the distance between the first edges of two adjacent negative electrode sheets is controlled within 1 mm.

[0062] In the above technical solution, by making the gap between the first edges of two adjacent negative electrode plates less than or equal to 1 mm, the cutting surface is made neater. On the one hand, this makes the gap between the positive and negative electrode plates smaller, which helps to shorten the ion path. On the other hand, it helps to reduce the volume occupation and improve the energy density.

[0063] As an optional technical solution in this application embodiment, in step S400, the distance between the cutting position of the negative electrode sheet and the separator and the positive electrode sheet is controlled within 3mm to 10mm along the first direction.

[0064] In the above technical solution, when the distance between the cutting position of the negative electrode and the separator and the positive electrode is greater than or equal to 3mm, the dimension of the negative electrode extending beyond the positive electrode along the first direction is relatively large, which is beneficial for meeting the overhang design and reducing the risk of lithium plating. When the distance between the cutting position of the negative electrode and the separator and the positive electrode is less than or equal to 10mm, the dimension of the negative electrode extending beyond the positive electrode along the first direction is not too large, which is beneficial for reducing the volume of the negative electrode and improving the energy density. Therefore, when the distance between the cutting position of the negative electrode and the separator and the positive electrode is within 3mm to 10mm, both the overhang design and the energy density can be improved.

[0065] As an optional technical solution in this application embodiment, in step S400, the distance between the cutting position of the negative electrode sheet and the separator and the positive electrode sheet is controlled within 5mm to 8mm along the first direction.

[0066] In the above technical solution, when the distance between the cutting position of the negative electrode and the separator and the positive electrode is greater than or equal to 5mm, the dimension of the negative electrode extending beyond the positive electrode along the first direction is relatively large, which is beneficial for meeting the overhang design and reducing the risk of lithium plating. When the distance between the cutting position of the negative electrode and the separator and the positive electrode is less than or equal to 8mm, the dimension of the negative electrode extending beyond the positive electrode along the first direction is not too large, which is beneficial for reducing the volume of the negative electrode and improving the energy density. Therefore, when the distance between the cutting position of the negative electrode and the separator and the positive electrode is within 5mm to 8mm, both the overhang design and the energy density can be improved.

[0067] As an optional technical solution in this application embodiment, in step S400, along the first direction, the distance between the first edge of the cut negative electrode sheet and the second edge of the isolation segment adjacent to the negative electrode sheet that is closest to the first edge is controlled within 2mm.

[0068] In the above technical solution, by making the distance between the first edge and the second edge less than or equal to 2mm, the edges of the negative electrode and the isolation section can be made more neat, which is beneficial to reduce volume occupation and improve energy density.

[0069] As an optional technical solution in this application embodiment, in step S400, the distance between the first edge of the cut negative electrode sheet and the second edge of the separator closest to the first edge is controlled within 1mm along the first direction.

[0070] In the above technical solution, by making the distance between the first edge and the second edge less than or equal to 1mm, the edges of the negative electrode and the isolation section can be made more neat, which is beneficial to reduce volume occupation and improve energy density.

[0071] As an optional technical solution in this application embodiment, step S300 includes: step S310: fixing at least partially the first extended portion of the two isolation sections adjacent to the positive electrode sheet by hot pressing.

[0072] In the above technical solution, the first extended portions of the two isolation sections are at least partially fixedly connected by hot pressing. On the one hand, this method is relatively convenient to manufacture, allowing the connection of the isolation sections on both sides of each positive electrode to be completed in one step. On the other hand, hot pressing is less likely to damage the positive and negative electrode sheets, which helps to improve the reliability of the electrode assembly.

[0073] Fourthly, embodiments of this application also provide a battery device, the battery device comprising the aforementioned battery cell.

[0074] Fifthly, embodiments of this application also provide an electrical device, the electrical device including the aforementioned battery cell, the battery cell being used to provide electrical energy to the electrical device. Attached Figure Description

[0075] 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.

[0076] Figure 1 is a structural schematic diagram of a vehicle provided in some embodiments of this application;

[0077] Figure 2 is an exploded view of a battery device provided in some embodiments of this application;

[0078] Figure 3 is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0079] Figure 4 is an exploded view of a single battery cell provided in some embodiments of this application;

[0080] Figure 5 is a cross-sectional view of an electrode assembly provided in some embodiments of this application from a first perspective.

[0081] Figure 6 is a cross-sectional view of the negative electrode sheet provided in some embodiments of this application;

[0082] Figure 7 is a cross-sectional view of an electrode assembly provided in some embodiments of this application from a second perspective;

[0083] Figure 8 is a schematic block diagram of an electrode assembly manufacturing method provided in some embodiments of this application;

[0084] Figure 9 is a schematic block diagram of an electrode assembly manufacturing method provided in some other embodiments of this application;

[0085] Figure 10 is a schematic diagram of the structure of the composite electrode provided in some embodiments of this application;

[0086] Figure 11 is a cross-sectional view of the product after step S220 provided in some embodiments of this application;

[0087] Figure 12 is a schematic block diagram of an electrode assembly manufacturing method provided in some embodiments of this application;

[0088] Figure 13 is a schematic block diagram of an electrode assembly manufacturing method provided in some embodiments of this application.

[0089] Icons: 10-Box; 11-First part; 12-Second part; 20-Battery cell; 21-Outer casing; 211-Housing shell; 212-End cap; 22-Electrode assembly; 221-Main body; 222-Negative electrode tab; 223-Positive electrode tab; 224-Negative electrode sheet; 2241-Negative electrode tab unit; 2242-Negative electrode sheet body; 22421-Negative electrode current collector; 2243-First edge; 225-Separator; 2251-Separator Section; 22511-First protruding part; 22512-Second edge; 22513-Second protruding part; 226-Positive electrode sheet; 2261-Positive electrode tab unit; 2262-Positive electrode sheet body; 227-Accommodation space; 228-Composite electrode sheet; 2281-Bending section; 23-Insulating component; 24-Electrode terminal; 30-Electrode assembly manufacturing method; 100-Battery device; 200-Controller; 300-Motor; 1000-Vehicle. Detailed Implementation

[0090] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0091] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0092] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0093] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" 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 direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication 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.

[0094] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0095] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0096] In this application, "multiple" means two or more (including two).

[0097] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0098] Battery cells include, but are not limited to, lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid batteries, etc.

[0099] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, reduces the risk of short circuits while allowing active ions to pass through.

[0100] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0101] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0102] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0103] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials in battery cells may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxide may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM)622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0104] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, lithium source material, potassium metal, or sodium metal can also be filled and / or deposited within the foamed metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0105] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0106] As an example, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. Foamed metal can be nickel foam, copper foam, aluminum foam, foam alloy, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0107] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0108] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0109] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials in battery cells may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0110] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0111] In some embodiments, the separator is a separator membrane. The separator membrane can be any known porous structure separator membrane with good chemical and mechanical stability.

[0112] As an example, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. The separator may be a separate component located between the positive and negative electrodes, or it may be attached to the surfaces of the positive and negative electrodes.

[0113] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0114] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or solid. Liquid electrolytes include electrolyte salts and solvents.

[0115] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0116] In some embodiments, the solvent may include at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0117] Among them, the gel electrolyte includes a polymer as the electrolyte backbone network, combined with an ionic liquid - lithium salt.

[0118] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0119] As an example, polymer solid electrolytes can be polyether (polyoxyethylene), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids-lithium salts, cellulose, etc.

[0120] As an example, inorganic solid electrolytes may include one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium germanium phosphate sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0121] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0122] In some implementations, the electrode assembly is a stacked structure.

[0123] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0124] As an example, multiple positive electrode plates can be provided, and negative electrode plates can be folded to form multiple stacked folded segments, with a positive electrode plate sandwiched between adjacent folded segments.

[0125] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0126] As an example, the separators can be arranged continuously, and can be folded between any adjacent positive or negative electrode plates.

[0127] In some implementations, the electrode assembly may be flat or polygonal in shape.

[0128] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0129] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as electrode assemblies and electrolytes. The housing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0130] In some embodiments, the housing can be a sealed structure or a non-sealed structure. As an example, when the housing is a sealed structure, it can protect the electrode assembly and prevent, to some extent, electrolyte leakage. When the housing is a non-sealed structure, it can still protect the electrode assembly, and a sealing bag may be included between the housing and the electrode assembly to encapsulate the electrode assembly and electrolyte. Specifically, the sealing bag can be a bag-shaped insulating component or an aluminum-plastic film.

[0131] As an example, a battery cell can be a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic battery cells, such as hexagonal prismatic battery cells.

[0132] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0133] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells; as an example, a battery cell assembly can be a battery module, which is formed by arranging multiple battery cells and fixing them together to form an independent module.

[0134] As an example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0135] In some embodiments, the battery device may be a battery pack, which may include a housing and one or more individual battery cells housed within the housing.

[0136] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0137] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0138] As an example, the enclosure may include a first part and a second part. The first and second parts are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or shutting off; it can be sealed or not sealed. The first part may be a top cover or a bottom plate.

[0139] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0140] As an example, the housing can be part of the vehicle's chassis structure. For instance, the housing's roof can be at least part of the vehicle's floor, or the housing's frame can be at least part of the vehicle's crossbeams and longitudinal beams.

[0141] In some embodiments, the battery device refers to an energy storage device, which includes a housing with a door on at least one side. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0142] Currently, judging from market trends, battery applications are becoming increasingly widespread. Batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also extensively in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. With the continuous expansion of battery applications, market demand is also constantly increasing.

[0143] The development of battery technology must consider multiple design factors simultaneously, such as energy density, cycle life, discharge capacity, and charge / discharge rate. Additionally, battery reliability must also be considered. However, current battery reliability is relatively poor.

[0144] A battery includes an electrode assembly, which is the component in the battery where electrochemical reactions occur. The electrode assembly is mainly composed of a positive electrode, a separator, and a negative electrode stacked together. During the manufacturing of the electrode assembly, the negative electrode must extend beyond the positive electrode by a predetermined amount; otherwise, lithium plating is likely to occur. However, when using ultra-thin negative electrode sheets for stacking, due to the smaller thickness and softer nature of the negative electrode, it is difficult to ensure that the negative electrode extends beyond the positive electrode by the predetermined amount, resulting in relatively poor battery reliability.

[0145] In view of this, this application provides a battery cell, which includes a casing and an electrode assembly housed within the casing. The electrode assembly includes a negative electrode, a separator, and a positive electrode, which are stacked together. The negative electrode includes a negative electrode tab unit and a negative electrode body, with the negative electrode tab unit connected to one side of the negative electrode body. The thickness of the negative electrode body is 10 μm to 30 μm. The separator has a separating section that separates the positive and negative electrode. The separating section has first protruding portions extending beyond the positive electrode on both sides in a first direction. At least partially, the first protruding portions of two adjacent separating sections are fixedly connected to cover at least a portion of the edge of the positive electrode. The first direction is perpendicular to the stacking direction of the positive electrode, the separator, and the negative electrode.

[0146] The negative electrode body of this battery cell has a thickness of 10μm to 30μm, meaning it is an ultra-thin negative electrode. The negative electrode is relatively soft, making it difficult for it to extend beyond the positive electrode along the first direction during stacking. By fixing at least partially the first extending portions of the two adjacent insulating sections to the positive electrode to cover at least a portion of the edge of the positive electrode, the position of the positive electrode can be limited, thus facilitating the negative electrode to extend beyond the positive electrode along the first direction and reducing the risk of lithium plating. Furthermore, it can prevent dendrite growth, thereby reducing the risk of short circuits and improving the reliability of the battery cell.

[0147] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use battery cells and battery devices, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships and spacecraft, etc. For example, spacecraft include airplanes, rockets, space shuttles and spacecraft.

[0148] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0149] Please refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of this application. A battery device 100 is disposed inside the vehicle 1000, and the battery device 100 may be located at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000; for example, the battery device 100 can serve as the operating power source for the vehicle 1000.

[0150] The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, for the power needs of the vehicle 1000 during startup, navigation and driving.

[0151] In some embodiments of this application, the battery device 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0152] Please refer to Figure 2, which is an exploded view of a battery device 100 provided in some embodiments of this application. The battery device 100 may include a housing 10 and battery cells 20, with the housing 10 used to house the battery cells 20.

[0153] The housing 10 has an enclosed space inside for accommodating the battery cells 20. The housing 10 can have various structures. In some embodiments, the housing 10 may include a first part 11 and a second part 12, which are interlocked. The first part 11 and the second part 12 can have various shapes, such as cuboids or cylinders. The first part 11 can be a hollow structure open on one side, and the second part 12 can also be a hollow structure open on one side. The open side of the second part 12 interlocks with the open side of the first part 11, thus forming a housing 10 with an enclosed space. Alternatively, the first part 11 can be a hollow structure open on one side, and the second part 12 can be a plate-like structure, with the second part 12 interlocking with the open side of the first part 11, thus forming a housing 10 with an accommodating space.

[0154] In the battery device 100, there can be one or more battery cells 20. If there are multiple battery cells 20, they can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells 20 are connected in both series and parallel. Alternatively, multiple battery cells 20 can be first connected in series, parallel, or in a mixed configuration to form a battery module, and then multiple battery modules can be connected in series, parallel, or in a mixed configuration to form a whole, which is then housed within the housing 10. Another option is that all battery cells 20 can be directly connected in series, parallel, or in a mixed configuration, and then the whole consisting of all battery cells 20 is housed within the housing 10.

[0155] In some embodiments, the battery device 100 may further include a busbar component, through which multiple battery cells 20 can be electrically connected to each other to achieve series, parallel, or mixed connection of the multiple battery cells 20. The busbar component may be a metallic conductor, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0156] Please refer to Figures 3, 4, 5, and 6. Figure 3 is a schematic diagram of the structure of a battery cell 20 provided in some embodiments of this application. Figure 4 is an exploded view of a battery cell 20 provided in some embodiments of this application. Figure 5 is a cross-sectional view of an electrode assembly 22 provided in some embodiments of this application from a first perspective. Figure 6 is a cross-sectional view of a negative electrode sheet 224 provided in some embodiments of this application. This application provides a battery cell 20, which includes a housing 21 and an electrode assembly 22, with the electrode assembly 22 housed within the housing 21. The electrode assembly 22 includes a negative electrode sheet 224, a separator 225, and a positive electrode sheet 226, which are stacked together. The negative electrode sheet 224 includes a negative electrode tab unit 2241 and a negative electrode sheet body 2242. The negative electrode tab unit 2241 is connected to one side of the negative electrode sheet body 2242, and the thickness of the negative electrode sheet body 2242 is 10 μm to 30 μm. The separator 225 has a separator segment 2251 separating the positive electrode 226 and the negative electrode 224. The separator segment 2251 has first protruding portions 22511 extending beyond the positive electrode 226 on both sides in a first direction. The first protruding portions 22511 of two separator segments 2251 adjacent to the positive electrode 226 are at least partially fixedly connected to cover at least a portion of the edge of the positive electrode 226. The first direction is perpendicular to the stacking direction of the positive electrode 226, the separator 225, and the negative electrode 224.

[0157] Battery cell 20 refers to the smallest unit that makes up battery device 100.

[0158] In some embodiments, the housing 21 may include a housing 211 and an end cap 212, the housing 211 having an opening and the end cap 212 closing the opening of the housing 211. Here, "closing" refers to covering or shutting down, and can be either sealed or unsealed.

[0159] End cap 212 is a component that covers the opening of housing 211 to isolate the internal environment of battery cell 20 from the external environment. The shape of end cap 212 can be adapted to the shape of housing 211 to fit it. Optionally, end cap 212 can be made of a material with certain hardness and strength (such as aluminum alloy), so that end cap 212 is not easily deformed under pressure and impact, giving battery cell 20 higher structural strength and improved reliability. The material of end cap 212 can include, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. Battery cell 20 also includes an insulating member 23, which is disposed inside end cap 212. The insulating member 23 can be used to isolate the electrical connection components inside housing 211 from end cap 212 to reduce the risk of short circuit. For example, insulating member 23 can be plastic, rubber, etc.

[0160] The housing 211 is a component used to cooperate with the end cap 212 to form the internal environment of the battery cell 20. This internal environment can accommodate the electrode assembly 22, electrolyte, and other components. The housing 211 and the end cap 212 can be independent components. An opening can be provided on the housing 211, and the end cap 212 can be used to close the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 212 and the housing 211 can be integrated. Specifically, the end cap 212 and the housing 211 can form a common mating surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 211, the end cap 212 closes the housing 211. The housing 211 can have various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 211 can be determined according to the specific shape and size of the electrode assembly 22. The material of the housing 211 can include, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0161] In an embodiment where the housing 211 has an opening at one end, one end cap 212 may be provided. In an embodiment where the housing 211 has openings at opposite ends, two end caps 212 may be provided, with the two end caps 212 respectively closing the two openings of the housing 211. The two end caps 212 and the housing 211 together define the receiving space for accommodating the electrode assembly 22.

[0162] Electrode assembly 22 is the component in the battery cell 20 where the electrochemical reaction occurs. The casing 211 may contain one or more electrode assemblies 22. The electrode assembly 22 is mainly formed by stacking positive electrode plates 226 and negative electrode plates 224, and typically a separator 225 is provided between the positive electrode plates 226 and negative electrode plates 224. The portions of the positive electrode plates 226 and 224 containing active material constitute the main body 221 of the electrode assembly 22, the portions of the positive electrode plates 226 without active material constitute positive electrode tab units 2261, and the portions of the negative electrode plates 224 without active material constitute negative electrode tab units 2241. To ensure that a large current can pass through without melting, multiple positive electrode tab units 2261 are stacked together to form positive electrode tabs 223, and multiple negative electrode tab units 2241 are stacked together to form negative electrode tabs 222. The positive electrode tabs 223 and negative electrode tabs 222 may be located together at one end of the main body 221 or separately at both ends of the main body 221. During the charging and discharging process of the battery device 100, the positive electrode active material and the negative electrode active material react with the electrolyte.

[0163] The negative electrode 224 includes a negative electrode tab unit 2241 and a negative electrode body 2242. The negative electrode tab unit 2241 is connected to one side of the negative electrode body 2242. The negative electrode body 2242 has a negative electrode active material, while the negative electrode tab unit 2241 does not have a negative electrode active material.

[0164] The statement "the thickness of the negative electrode body 2242 is 10μm to 30μm" refers to the thickness of the negative electrode body 2242 when the battery cell 20 is fully discharged to 0% SOC. Referring to Figure 6, the thickness of the negative electrode body 2242 can be represented by H, i.e., 10μm ≤ H ≤ 30μm. When 10μm ≤ H ≤ 30μm, the negative electrode 224 is an ultra-thin negative electrode.

[0165] The thickness of the negative electrode body 2242 can be: H = 10μm, 12μm, 15μm, 18μm, 20μm, 22μm, 25μm, 28μm, 30μm, etc.

[0166] When there are multiple separators 225, and each separator 225 is disposed between adjacent positive electrode plates 226 or negative electrode plates 224, the separator 225 as a whole can serve as a separator segment 2251. When the separator 225 is a continuous structure disposed between any adjacent positive electrode plates 226 or negative electrode plates 224 by folding, the separator 225 includes multiple separator segments 2251, which are arranged along the stacking direction of the positive electrode plate 226, the separator 225, and the negative electrode plate 224, and each separator segment 2251 is used to separate the positive electrode plate 226 and the negative electrode plate 224.

[0167] The first extending portion 22511 is the part of the isolation section 2251 that extends beyond the positive electrode plate 226 along the first direction. The isolation section 2251 extends beyond the positive electrode plate 226 on both sides along the first direction. In other words, the isolation section 2251 has two first extending portions 22511, and the two first extending portions 22511 are arranged at intervals along the first direction.

[0168] Referring to Figure 5, the stacking direction of the positive electrode 226, the separator 225, and the negative electrode 224 is the X direction shown in the figure. A first direction perpendicular to the stacking direction can be the Y direction shown in the figure.

[0169] Referring to Figure 5, along the stacking direction, the first extension portions 22511 of two isolation segments 2251 located on both sides of the positive electrode sheet 226 are fixedly connected. During connection, the first extension portion 22511 of one isolation segment 2251 and the first extension portion 22511 of the other isolation segment 2251 located on the same side as the aforementioned first extension portion 22511 are fixedly connected. Referring to Figure 5, the first extension portion 22511 on the left side of one isolation segment 2251 and the first extension portion 22511 on the left side of the other isolation segment 2251 are connected, and the first extension portion 22511 on the right side of one isolation segment 2251 and the first extension portion 22511 on the right side of the other isolation segment 2251 are connected.

[0170] The thickness of the negative electrode body 2242 of the battery cell 20 is 10μm to 30μm, that is, the negative electrode 224 is an ultra-thin negative electrode. The negative electrode 224 is relatively soft, and it is not easy for the negative electrode 224 to extend beyond the positive electrode 226 in the first direction during stacking. By fixing at least partially the first protruding portion 22511 of the two isolation sections 2251 adjacent to the positive electrode 226 to cover at least a portion of the edge of the positive electrode 226, on the one hand, the position of the positive electrode 226 can be limited, which is conducive to the negative electrode 224 extending beyond the positive electrode 226 in the first direction and reducing the risk of lithium plating. On the other hand, it can prevent dendrite growth around the positive electrode, thereby reducing the risk of short circuit and improving the reliability of the battery cell 20.

[0171] In some embodiments, the battery cell 20 may further include electrode terminals 24 disposed on the housing 21. The electrode terminals 24 are used for electrical connection with the tabs of the electrode assembly 22 to input or output electrical energy from the battery cell 20. The electrode terminals 24 may be disposed on the housing 211 of the housing 21 or on the end cap 212 of the housing 21. The electrode terminals 24 and the tabs may be directly connected, for example, by welding the electrode terminals 24 to the tabs. The electrode terminals 24 and the tabs may also be indirectly connected, for example, by connecting the electrode terminals 24 to the tabs via a current collector. The current collector may be a metallic conductor, such as copper, iron, aluminum, steel, or aluminum alloy.

[0172] As an example, as shown in Figures 3 and 4, one end of the housing 211 forms an opening, and there is one end cap 212 in the housing 21, which closes one opening of the housing 211. Two electrode terminals 24 are provided on the end cap 212, which are a positive electrode terminal and a negative electrode terminal, respectively. The end of the electrode assembly 22 facing the end cap 212 has a positive electrode tab 223 and a negative electrode tab 222. The positive electrode terminal is electrically connected to the positive electrode tab 223, and the negative electrode terminal is electrically connected to the negative electrode tab 222.

[0173] Please refer to Figures 3, 4, 5 and 6. In some embodiments, the thickness of the negative electrode body 2242 is 10 μm to 20 μm.

[0174] The thickness of the negative electrode body 2242 can be: H = 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, etc.

[0175] The negative electrode body 2242 is thinner and the negative electrode 224 is softer. By fixing at least part of the first overhang 22511 of the two isolation sections 2251 adjacent to the positive electrode 226 to cover at least part of the edge of the positive electrode 226, a better effect can be achieved.

[0176] Referring to Figures 3, 4, 5, and 6, in some embodiments, the negative electrode body 2242 includes a negative electrode current collector 22421, which is made of aluminum. The positive electrode 226 includes a positive electrode active material capable of reversibly extracting and inserting sodium ions, which includes a sodium-containing compound.

[0177] If the negative electrode current collector 22421 is made of aluminum and the positive electrode active material is a sodium-containing compound, then the battery cell 20 is a sodium-ion battery cell.

[0178] The negative current collector 22421 is made of aluminum, and the negative electrode 224 is softer. By fixing at least part of the first overhang 22511 of the two isolation sections 2251 adjacent to the positive electrode 226 to cover at least part of the edge of the positive electrode 226, a better effect can be achieved.

[0179] In other embodiments, the negative electrode current collector 22421 is made of at least one of copper, nickel, molybdenum, titanium, niobium, and iron. The negative electrode current collector 22421 can be made of pure metal or an alloy. For example, the negative electrode current collector 22421 can be made of copper, nickel, or stainless steel. In some embodiments, the negative electrode body 2242 further includes a functional coating disposed on the negative electrode current collector 22421, the functional coating including a conductivity-enhancing coating, a metal affinity coating, etc.

[0180] In other embodiments, the negative electrode current collector 22421 can be a current collector that combines support capabilities and functional elements, such as carbon cloth, carbon film, carbonaceous material, porous current collector, alloy-modified current collector, lithium-loving / sodium-modified current collector, etc.

[0181] Referring to Figures 3, 4, 5, and 6, in some embodiments, the electrode assembly 22 includes a plurality of negative electrode plates 224 and a plurality of positive electrode plates 226. Along the stacking direction, the plurality of negative electrode plates 224 are spaced apart, and the positive electrode plates 226 are disposed between two adjacent negative electrode plates 224. An isolation section 2251 separates the positive electrode plates 226 and the negative electrode plates 224.

[0182] Multiple positive electrode plates 226 and multiple negative electrode plates 224 are provided, and multiple positive electrode plates 226 and multiple negative electrode plates 224 are stacked alternately. An isolation section 2251 is provided between the positive electrode plates 226 and the negative electrode plates 224.

[0183] Multiple negative electrode plates 224 and multiple positive electrode plates 226 are stacked together, with an isolation section 2251 separating the positive electrode plates 226 and the negative electrode plates 224. This eliminates the bending area in the negative electrode plate 224, reducing its volume and increasing energy density. During manufacturing, a large negative electrode plate 224 can be continuously bent and stacked, and then cut to form multiple smaller negative electrode plates 224.

[0184] Referring to Figures 3, 4, 5 and 6, in some embodiments, along the first direction, the negative electrode 224 has a first edge 2243, and the distance between the first edges 2243 of two adjacent negative electrode 224 is L1, satisfying: 0≤L1≤2mm.

[0185] The first edge 2243 specifically refers to an edge of the negative electrode 224 along a first direction.

[0186] L1 represents the distance between the first edges 2243 of two adjacent negative electrode plates 224. It should be noted that the first edges 2243 of the two negative electrode plates 224 are located on the same side of the positive electrode plate 226 along the first direction.

[0187] The spacing between the first edges 2243 of two adjacent negative electrode plates 224 can be: L1 = 2mm, 1.8mm, 1.5mm, 1.2mm, 1mm, 0.8mm, 0.5mm, 0.2mm, 0, etc.

[0188] By making the gap between the first edges 2243 of two adjacent negative electrode plates 224 less than or equal to 2mm, the first edges 2243 of the multiple negative electrode plates 224 of the electrode assembly 22 can be made more uniform, which is beneficial to reduce volume occupation and improve energy density.

[0189] Optionally, 0 ≤ L1 ≤ 1 mm.

[0190] The spacing between the first edges 2243 of two adjacent negative electrode plates 224 can be: L1 = 1mm, 0.9mm, 0.8mm, 0.7mm, 0.6mm, 0.5mm, 0.4mm, 0.3mm, 0.2mm, 0.1mm, 0, etc.

[0191] By making the gap between the first edges 2243 of two adjacent negative electrode plates 224 less than or equal to 1 mm, the first edges 2243 of the multiple negative electrode plates 224 of the electrode assembly 22 can be made more uniform, which is beneficial to reduce volume occupation and improve energy density.

[0192] Referring to Figures 3, 4, 5, and 6, in some embodiments, along a first direction, the negative electrode 224 has a first edge 2243, and the isolation segment 2251 adjacent to the negative electrode 224 has a second edge 22512 closest to the first edge 2243. The distance between the first edge 2243 and the second edge 22512 is L2, satisfying: 0 ≤ L2 ≤ 2 mm.

[0193] The second edge 22512 is the edge of the isolation segment 2251 along the first direction, and the second edge 22512 is the edge closest to the first edge 2243 of the negative electrode 224. In other words, the first edge 2243 and the second edge 22512 are located on the same side of the positive electrode 226 along the first direction.

[0194] L2 represents the distance between the first edge 2243 along the first direction and the second edge 22512.

[0195] The distance between the first edge 2243 along the first direction and the second edge 22512 can be: L2 = 2mm, 1.8mm, 1.5mm, 1.2mm, 1mm, 0.8mm, 0.5mm, 0.2mm, 0, etc.

[0196] By making the distance between the first edge 2243 and the second edge 22512 less than or equal to 2mm, the edges of the negative electrode 224 and the isolation section 2251 can be made more uniform, which is beneficial to reduce volume occupation and improve energy density.

[0197] Optionally, 0 ≤ L2 ≤ 1 mm.

[0198] The distance between the first edge 2243 along the first direction and the second edge 22512 can be: L2 = 1mm, 0.9mm, 0.8mm, 0.7mm, 0.6mm, 0.5mm, 0.4mm, 0.3mm, 0.2mm, 0.1mm, 0, etc.

[0199] By making the distance between the first edge 2243 and the second edge 22512 less than or equal to 1 mm, the edges of the negative electrode 224 and the isolation section 2251 can be made neater, which is beneficial to reduce volume occupation and improve energy density.

[0200] Referring to Figures 3, 4, 5 and 6, in some embodiments, along the first direction, the negative electrode body 2242 extends beyond the positive electrode 226 by a dimension L3, satisfying: 3mm≤L3≤10mm.

[0201] L3 indicates the dimension by which the negative electrode body 2242 extends beyond the positive electrode body 226 along the first direction. It should be noted that the positive electrode body 226 includes a positive electrode tab unit 2261 and a positive electrode body 2262. The positive electrode tab unit 2261 is connected to one side of the positive electrode body 2262 along the second direction. The negative electrode body 2242 has a negative electrode active material, while the negative electrode tab unit 2241 does not. L3 indicates the dimension by which the negative electrode body 2242 extends beyond the positive electrode body 2262 along the first direction.

[0202] The negative electrode body 2242 extending beyond the positive electrode 226 along the first direction can be L3 = 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, 10mm, etc.

[0203] When L3 ≥ 3 mm, the negative electrode body 2242 extends significantly beyond the positive electrode 226 along the first direction, which is beneficial for meeting the overhang design and reducing the risk of lithium plating. When L3 ≤ 10 mm, the extension of the negative electrode body 2242 beyond the positive electrode 226 along the first direction is not excessive, which helps to reduce the volume of the negative electrode 224 and improve energy density. Therefore, when 3 mm ≤ L3 ≤ 10 mm, both the overhang design and energy density can be improved.

[0204] Optionally, 5mm≤L3≤8mm.

[0205] The negative electrode body 2242 extending beyond the positive electrode 226 along the first direction can be L3 = 5mm, 5.2mm, 5.5mm, 5.8mm, 6mm, 6.2mm, 6.5mm, 6.8mm, 7mm, 7.2mm, 7.5mm, 7.8mm, 8mm, etc.

[0206] When L3 ≥ 5 mm, the negative electrode body 2242 extends significantly beyond the positive electrode 226 along the first direction, which is more conducive to meeting the overhang design and reducing the risk of lithium plating. When L3 ≤ 8 mm, the negative electrode body 2242 does not extend excessively beyond the positive electrode 226 along the first direction, which helps to reduce the volume of the negative electrode 224 and improve energy density. Therefore, when 5 mm ≤ L3 ≤ 8 mm, both the overhang design and energy density can be improved.

[0207] Please refer to Figures 3, 4, 5, 6, and 7. Figure 7 is a cross-sectional view of the electrode assembly 22 provided in some embodiments of this application from a second perspective. In some embodiments, the positive electrode 226 includes a positive electrode tab unit 2261 and a positive electrode body 2262. The positive electrode tab unit 2261 is connected to one side of the positive electrode body 2262 along a second direction. The isolation segment 2251 has second protruding portions 22513 extending beyond the positive electrode body 2262 on both sides in the second direction. The second protruding portions 22513 of two isolation segments 2251 adjacent to the positive electrode body 2262 are at least partially fixedly connected to cover at least a portion of the edge of the positive electrode body 2262. The first direction, the second direction, and the stacking direction are perpendicular to each other.

[0208] The positive electrode 226 includes a positive electrode tab unit 2261 and a positive electrode body 2262. The positive electrode tab unit 2261 is connected to one side of the positive electrode body 2262 along the second direction. The positive electrode body 2262 has a positive electrode active material, while the positive electrode tab unit 2261 does not have a positive electrode active material.

[0209] The second extending portion 22513 is the portion of the isolation section 2251 that extends beyond the positive electrode plate 226 along the second direction. The isolation section 2251 extends beyond the positive electrode plate 226 on both sides along the second direction. In other words, the isolation section 2251 has two second extending portions 22513, which are spaced apart along the second direction.

[0210] Please refer to Figure 7. The second direction can be the Z direction shown in the figure.

[0211] Referring to Figure 7, along the stacking direction, the second extension portions 22513 of two isolation segments 2251 located on both sides of the positive electrode 226 are fixedly connected. During connection, the second extension portion 22513 of one isolation segment 2251 and the second extension portion 22513 of the other isolation segment 2251 located on the same side as the aforementioned second extension portion 22513 are fixedly connected. Referring to Figure 7, the second extension portion 22513 on the left side of one isolation segment 2251 and the second extension portion 22513 on the left side of the other isolation segment 2251 are connected, and the second extension portion 22513 on the right side of one isolation segment 2251 and the second extension portion 22513 on the right side of the other isolation segment 2251 are connected.

[0212] By at least partially fixing the second extension portion 22513 of the two isolation segments 2251 adjacent to the positive electrode body 2262 to cover at least a portion of the edge of the positive electrode body 2262, the position of the positive electrode 226 can be limited, thereby facilitating the negative electrode 224 to extend beyond the positive electrode 226 in the first direction and reducing the risk of lithium plating. On the other hand, dendrite growth can be prevented, thereby reducing the risk of short circuit and improving the reliability of the battery cell 20.

[0213] Please refer to Figures 3, 4, 5, 6 and 7. In some embodiments, two isolation segments 2251 adjacent to the positive electrode 226 are connected to form a closed receiving space 227, and the positive electrode body 2262 is received within the receiving space 227.

[0214] Along the stacking direction, two isolation sections 2251 located on both sides of the positive electrode 226 are fixedly connected and form a closed receiving space 227. The positive electrode body 2262 is received in the receiving space 227, and the positive electrode tab unit 2261 extends out of the receiving space 227.

[0215] By accommodating the positive electrode body 2262 within the accommodating space 227, on the one hand, the position of the positive electrode body 2262 can be limited, thereby facilitating the negative electrode 224 to extend beyond the positive electrode 226 along the first direction and reducing the risk of lithium plating. On the other hand, it can further prevent dendrite growth, thereby reducing the risk of short circuit and improving the reliability of the battery cell 20.

[0216] Referring to Figures 5, 6, and 7, this embodiment of the application also provides an electrode assembly 22, which includes a negative electrode 224, an isolator 225, and a positive electrode 226, which are stacked together. The negative electrode 224 includes a negative electrode tab unit 2241 and a negative electrode body 2242, with the tab unit 2241 connected to one side of the negative electrode body 2242. The thickness of the negative electrode body 2242 is 10 μm to 30 μm. The isolator 225 has an isolating segment 2251 separating the positive electrode 226 and the negative electrode 224. The isolating segment 2251 has first protruding portions 22511 extending beyond the positive electrode 226 on both sides in a first direction. The first protruding portions 22511 of two isolating segments 2251 adjacent to the positive electrode 226 are at least partially fixedly connected to cover at least a portion of the edge of the positive electrode 226. The first direction is perpendicular to the stacking direction of the positive electrode 226, the separator 225 and the negative electrode 224.

[0217] The negative electrode body 2242 of the electrode assembly 22 has a thickness of 10μm to 30μm, meaning the negative electrode 224 is an ultra-thin negative electrode. The negative electrode 224 is relatively soft, making it less likely to extend beyond the positive electrode 226 along the first direction during stacking. By at least partially fixing the first protruding portion 22511 of the two adjacent isolation sections 2251 to the positive electrode 226 to cover at least a portion of the edge of the positive electrode 226, the position of the positive electrode 226 can be limited, thereby facilitating the negative electrode 224 to extend beyond the positive electrode 226 along the first direction and reducing the risk of lithium plating. Furthermore, it can prevent dendrite growth, thereby reducing the risk of short circuits and improving the reliability of the battery cell 20.

[0218] Please refer to Figures 5, 6 and 7. In some embodiments, the thickness of the negative electrode body 2242 is 10 μm to 20 μm.

[0219] The thickness of the negative electrode body 2242 can be: H = 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, etc.

[0220] The negative electrode body 2242 is thinner and the negative electrode 224 is softer. By fixing at least part of the first overhang 22511 of the two isolation sections 2251 adjacent to the positive electrode 226 to cover at least part of the edge of the positive electrode 226, a better effect can be achieved.

[0221] Referring to Figures 5, 6, and 7, in some embodiments, the negative electrode body 2242 includes a negative electrode current collector 22421, which is made of aluminum. The positive electrode 226 includes a positive electrode active material capable of reversibly extracting and inserting sodium ions, which includes a sodium-containing compound.

[0222] If the negative electrode current collector 22421 is made of aluminum and the positive electrode active material is a sodium-containing compound, then the battery cell 20 is a sodium-ion battery cell.

[0223] The negative current collector 22421 is made of aluminum, and the negative electrode 224 is softer. By fixing at least part of the first overhang 22511 of the two isolation sections 2251 adjacent to the positive electrode 226 to cover at least part of the edge of the positive electrode 226, a better effect can be achieved.

[0224] Referring to Figures 5, 6, and 7, in some embodiments, the electrode assembly 22 includes a plurality of negative electrode plates 224 and a plurality of positive electrode plates 226. Along the stacking direction, the plurality of negative electrode plates 224 are spaced apart, and the positive electrode plates 226 are disposed between two adjacent negative electrode plates 224. An isolation section 2251 separates the positive electrode plates 226 and the negative electrode plates 224.

[0225] Multiple positive electrode plates 226 and multiple negative electrode plates 224 are provided, and multiple positive electrode plates 226 and multiple negative electrode plates 224 are stacked alternately. An isolation section 2251 is provided between the positive electrode plates 226 and the negative electrode plates 224.

[0226] Multiple negative electrode sheets 224 and multiple positive electrode sheets 226 are stacked together, with an isolation section 2251 separating the positive electrode sheets 226 and the negative electrode sheets 224. This eliminates the bending area of ​​the negative electrode sheet 224, reducing its volume and increasing energy density. During manufacturing, a large negative electrode sheet 224 can be continuously bent and stacked, and then cut to form multiple negative electrode sheets 224.

[0227] Referring to Figures 5, 6 and 7, in some embodiments, along the first direction, the negative electrode 224 has a first edge 2243, and the distance between the first edges 2243 of two adjacent negative electrode 224 is L1, satisfying: 0≤L1≤2mm.

[0228] The first edge 2243 specifically refers to one edge of the negative electrode 224 along the first direction. L1 represents the distance between the first edges 2243 of two adjacent negative electrode 224s. It should be noted that the first edges 2243 of the two negative electrode 224s are located on the same side of the positive electrode 226 along the first direction. The distance between the first edges 2243 of two adjacent negative electrode 224s can be: L1 = 2mm, 1.8mm, 1.5mm, 1.2mm, 1mm, 0.8mm, 0.5mm, 0.2mm, 0, etc.

[0229] By making the gap between the first edges 2243 of two adjacent negative electrode plates 224 less than or equal to 2mm, the first edges 2243 of the multiple negative electrode plates 224 of the electrode assembly 22 can be made more uniform, which is beneficial to reduce volume occupation and improve energy density.

[0230] Optionally, 0 ≤ L1 ≤ 1 mm.

[0231] The spacing between the first edges 2243 of two adjacent negative electrode plates 224 can be: L1 = 1mm, 0.9mm, 0.8mm, 0.7mm, 0.6mm, 0.5mm, 0.4mm, 0.3mm, 0.2mm, 0.1mm, 0, etc.

[0232] By making the gap between the first edges 2243 of two adjacent negative electrode plates 224 less than or equal to 1 mm, the first edges 2243 of the multiple negative electrode plates 224 of the electrode assembly 22 can be made more uniform, which is beneficial to reduce volume occupation and improve energy density.

[0233] Referring to Figures 5, 6, and 7, in some embodiments, along a first direction, the negative electrode 224 has a first edge 2243, and the isolation segment 2251 adjacent to the negative electrode 224 has a second edge 22512 closest to the first edge 2243. The distance between the first edge 2243 and the second edge 22512 is L2, satisfying: 0 ≤ L2 ≤ 2 mm.

[0234] The second edge 22512 is the edge of the isolation segment 2251 along the first direction, and the second edge 22512 is the edge closest to the first edge 2243 of the negative electrode 224. In other words, the first edge 2243 and the second edge 22512 are located on the same side of the positive electrode 226 along the first direction. L2 represents the distance between the first edge 2243 and the second edge 22512 along the first direction. The distance between the first edge 2243 and the second edge 22512 along the first direction can be: L2 = 2mm, 1.8mm, 1.5mm, 1.2mm, 1mm, 0.8mm, 0.5mm, 0.2mm, 0, etc.

[0235] By making the distance between the first edge 2243 and the second edge 22512 less than or equal to 2mm, the edges of the negative electrode 224 and the isolation section 2251 can be made more uniform, which is beneficial to reduce volume occupation and improve energy density.

[0236] Optionally, 0 ≤ L2 ≤ 1 mm.

[0237] The distance between the first edge 2243 along the first direction and the second edge 22512 can be: L2 = 1mm, 0.9mm, 0.8mm, 0.7mm, 0.6mm, 0.5mm, 0.4mm, 0.3mm, 0.2mm, 0.1mm, 0, etc.

[0238] By making the distance between the first edge 2243 and the second edge 22512 less than or equal to 1 mm, the edges of the negative electrode 224 and the isolation section 2251 can be made neater, which is beneficial to reduce volume occupation and improve energy density.

[0239] Referring to Figures 5, 6 and 7, in some embodiments, along the first direction, the negative electrode body 2242 extends beyond the positive electrode 226 by a dimension L3, satisfying: 3mm≤L3≤10mm.

[0240] L3 represents the dimension by which the negative electrode body 2242 extends beyond the positive electrode 226 along the first direction. It should be noted that the positive electrode 226 includes a positive electrode tab unit 2261 and a positive electrode body 2262. The positive electrode tab unit 2261 is connected to one side of the positive electrode body 2262 along the second direction. The negative electrode body 2242 has a negative electrode active material, while the negative electrode tab unit 2241 does not. L3 represents the dimension by which the negative electrode body 2242 extends beyond the positive electrode body 2262 along the first direction. The dimension by which the negative electrode body 2242 extends beyond the positive electrode 2266 along the first direction can be: L3 = 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, 10mm, etc.

[0241] When L3 ≥ 3 mm, the negative electrode body 2242 extends significantly beyond the positive electrode 226 along the first direction, which is beneficial for meeting the overhang design and reducing the risk of lithium plating. When L3 ≤ 10 mm, the negative electrode body 2242 does not extend excessively beyond the positive electrode 226 along the first direction, which is beneficial for reducing the volume of the negative electrode 224 and improving energy density. Therefore, when 3 mm ≤ L3 ≤ 10 mm, both the overhang design and energy density can be improved.

[0242] Optionally, 5mm≤L3≤8mm.

[0243] The negative electrode body 2242 extending beyond the positive electrode 226 along the first direction can be L3 = 5mm, 5.2mm, 5.5mm, 5.8mm, 6mm, 6.2mm, 6.5mm, 6.8mm, 7mm, 7.2mm, 7.5mm, 7.8mm, 8mm, etc.

[0244] When L3 ≥ 5 mm, the negative electrode body 2242 extends significantly beyond the positive electrode 226 along the first direction, which is more conducive to meeting the overhang design and reducing the risk of lithium plating. When L3 ≤ 8 mm, the negative electrode body 2242 does not extend excessively beyond the positive electrode 226 along the first direction, which helps to reduce the volume of the negative electrode 224 and improve energy density. Therefore, when 5 mm ≤ L3 ≤ 8 mm, both the overhang design and energy density can be improved.

[0245] Referring to Figures 5, 6, and 7, in some embodiments, the positive electrode 226 includes a positive electrode tab unit 2261 and a positive electrode body 2262. The positive electrode tab unit 2261 is connected to one side of the positive electrode body 2262 along a second direction. The insulating segment 2251 has second protruding portions 22513 extending beyond the positive electrode body 2262 on both sides in the second direction. At least partially, the second protruding portions 22513 of two insulating segments 2251 adjacent to the positive electrode body 2262 are fixedly connected to cover at least a portion of the edge of the positive electrode body 2262. The first direction, the second direction, and the stacking direction are mutually perpendicular.

[0246] The positive electrode 226 includes a positive electrode tab unit 2261 and a positive electrode body 2262. The positive electrode tab unit 2261 is connected to one side of the positive electrode body 2262 along a second direction. The positive electrode body 2262 has a positive electrode active material, while the positive electrode tab unit 2261 does not. The second extension portion 22513 is the portion of the isolation section 2251 that extends beyond the positive electrode 226 along the second direction. Both sides of the isolation section 2251 extend beyond the positive electrode 226 along the second direction. In other words, the isolation section 2251 has two second extension portions 22513, which are spaced apart along the second direction. Referring to Figure 7, the second direction can be the Z direction shown in the figure. Referring to Figure 7, along the stacking direction, the second extension portions 22513 of the two isolation sections 2251 located on both sides of the positive electrode 226 are fixedly connected. During connection, the second extension portion 22513 of one isolation segment 2251 and the second extension portion 22513 of another isolation segment 2251 located on the same side as the aforementioned second extension portion 22513 are fixedly connected. Referring to Figure 7, the second extension portion 22513 on the left side of one isolation segment 2251 and the second extension portion 22513 on the left side of another isolation segment 2251 are connected, and the second extension portion 22513 on the right side of one isolation segment 2251 and the second extension portion 22513 on the right side of another isolation segment 2251 are connected.

[0247] By at least partially fixing the second extension portion 22513 of the two isolation segments 2251 adjacent to the positive electrode body 2262 to cover at least a portion of the edge of the positive electrode body 2262, the position of the positive electrode 226 can be limited, thereby facilitating the negative electrode 224 to extend beyond the positive electrode 226 in the first direction and reducing the risk of lithium plating. On the other hand, dendrite growth can be prevented, thereby reducing the risk of short circuit and improving the reliability of the battery cell 20.

[0248] Referring to Figures 5, 6, and 7, in some embodiments, two isolation segments 2251 adjacent to the positive electrode 226 are connected to form a closed receiving space 227, within which the positive electrode body 2262 is received. Along the stacking direction, two isolation segments 2251 located on both sides of the positive electrode 226 are fixedly connected to form the closed receiving space 227, within which the positive electrode body 2262 is received, and the positive electrode tab unit 2261 extends out of the receiving space 227. By receiving the positive electrode body 2262 within the receiving space 227, on the one hand, the position of the positive electrode body 2262 can be limited, thereby facilitating the negative electrode 224 to extend beyond the positive electrode 226 along the first direction, reducing the risk of lithium plating. On the other hand, it can further prevent dendrite growth, thereby reducing the risk of short circuits and improving the reliability of the battery cell 20.

[0249] Please refer to Figure 8, which is a schematic block diagram of an electrode assembly manufacturing method 30 provided in some embodiments of this application. This application also provides an electrode assembly manufacturing method 30, which includes:

[0250] Step S100: Provide a positive electrode 226, an insulating member 225 and a negative electrode 224. The negative electrode 224 includes a negative electrode tab unit 2241 and a negative electrode body 2242. The negative electrode tab unit 2241 is connected to one side of the negative electrode body 2242. The thickness of the negative electrode body 2242 is 10μm to 30μm.

[0251] Step S200: The positive electrode 226, the separator 225 and the negative electrode 224 are stacked. The separator 225 has a separator section 2251 that separates the positive electrode 226 and the negative electrode 224. The separator section 2251 has a first overhang portion 22511 that extends beyond the positive electrode 226 on both sides in a first direction. The first direction is perpendicular to the stacking direction of the positive electrode 226, the separator 225 and the negative electrode 224.

[0252] Step S300: At least partially fix the first extended portion 22511 of the two isolation segments 2251 adjacent to the positive electrode 226 to cover at least a portion of the edge of the positive electrode 226.

[0253] By at least partially fixing the first protruding portion 22511 of the two isolation segments 2251 adjacent to the positive electrode 226 to cover at least a portion of the edge of the positive electrode 226, the position of the positive electrode 226 can be limited, thereby facilitating the negative electrode 224 to extend beyond the positive electrode 226 in the first direction and reducing the risk of lithium plating. On the other hand, dendrite growth can be prevented, thereby reducing the risk of short circuit and improving the reliability of the battery cell 20.

[0254] In step S100, the thickness of the negative electrode body 2242 is 10μm to 20μm.

[0255] In step S100, the thickness of the negative electrode body 2242 can be: H = 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, etc.

[0256] The negative electrode body 2242 is thinner and the negative electrode 224 is softer. By fixing at least part of the first overhang 22511 of the two isolation sections 2251 adjacent to the positive electrode 226 to cover at least part of the edge of the positive electrode 226, a better effect can be achieved.

[0257] In some embodiments, in step S200, the difference between the maximum thickness of the negative electrode body 2242 and the minimum thickness of the negative electrode 224 is less than or equal to 2 μm.

[0258] The difference between the maximum thickness of the negative electrode body 2242 and the minimum thickness of the negative electrode 224 is less than or equal to 2μm, which means that the thickness of the negative electrode body 2242 is roughly the same at each position. In other words, there is no need to make marks on the negative electrode body 2242.

[0259] Optionally, the thickness of the negative electrode body 2242 is equal at all locations.

[0260] The thickness of the negative electrode body 2242 is equal at all locations, so there is no need to make marks on the negative electrode body 2242.

[0261] Please refer to Figure 9, which is a schematic block diagram of an electrode assembly manufacturing method 30 provided in other embodiments of this application. In other embodiments, step S200 includes:

[0262] Step S210: The positive electrode 226, the separator 225 and the negative electrode 224 are made into a composite electrode 228. The composite electrode 228 includes multiple positive electrode 226, which are alternately arranged on both sides of the negative electrode 224. Along the length of the composite electrode 228, the part of the composite electrode 228 located between two adjacent positive electrode 226 is a bent section 2281.

[0263] Step S220: Bend the bending section 2281 to stack the positive electrode 226, the separator 225 and the negative electrode 224.

[0264] Please refer to Figure 10, which is a schematic diagram of the structure of the composite electrode 228 provided in some embodiments of this application. Figure 10 shows the product after step S210. The composite electrode 228 includes a negative electrode 224 and a plurality of positive electrode 226, with the plurality of positive electrode 226 alternately disposed on both sides of the negative electrode 224. A spacer 225 is also disposed between the positive electrode 226 and the negative electrode 224.

[0265] Optionally, the composite electrode 228 includes two separators 225, which are respectively disposed on both sides of the negative electrode 224.

[0266] Please refer to Figure 10. The length direction of the composite electrode 228 is direction A as shown in the figure.

[0267] The portion of the composite electrode 228 located between two adjacent positive electrodes 226 is a bending section 2281. Since there is no positive electrode 226 in the bending section 2281 and the negative electrode 224 is an ultra-thin negative electrode, the bending section 2281 is relatively thin and easy to bend.

[0268] Please refer to Figure 11, which is a cross-sectional view of the product after step S220 provided in some embodiments of this application. Figure 11 shows the product after step S220. At this time, multiple positive electrode sheets 226 are provided, and negative electrode sheets 224 are folded to form multiple stacked folded segments, with a positive electrode sheet 226 sandwiched between adjacent folded segments.

[0269] By first fabricating a composite electrode 228, the bending section 2281 of the composite electrode 228 is relatively weak. The positive electrode 226, the separator 225 and the negative electrode 224 can be stacked by bending the bending section 2281, which makes the manufacturing simple and convenient. It also helps to make the negative electrode 224 extend beyond the positive electrode 226 in the first direction, reducing the risk of lithium plating.

[0270] Please refer to Figure 12, which is a schematic block diagram of an electrode assembly manufacturing method 30 provided in some embodiments of this application. In some embodiments, after step S300, the electrode assembly manufacturing method 30 further includes:

[0271] Step S400: Cut the negative electrode 224 and the separator 225 to remove the portion of the negative electrode 224 and the separator 225 located in the bent section 2281 of the composite electrode 228.

[0272] Please refer to Figure 5, which is a cross-sectional view of the product after step S400. In step S400, the electrode assembly 22 is shaped by cutting away the portion of the negative electrode 224 and the separator 225 located at the bent section 2281 of the composite electrode 228.

[0273] It should be noted that during the cutting process, the first extended portion 22511 of the two isolation sections 2251 adjacent to the positive electrode 226 must be kept in a fixed connection.

[0274] Because the negative electrode 224 is relatively soft, the bending section 2281 of the composite electrode 228 is prone to a large curvature. By cutting the negative electrode 224 and the separator 225, the portion of the negative electrode 224 and the separator 225 located at the bending section 2281 of the composite electrode 228 is removed, thus shaping the electrode assembly 22. On the one hand, this helps to make the interface of the electrode assembly 22 flat, resulting in a smaller gap between the positive and negative electrodes, which helps to shorten the ion path. On the other hand, it helps to reduce the volume occupation and increase the energy density.

[0275] In some embodiments, in step S400, along the first direction, the negative electrode 224 has a first edge 2243, and the distance between the first edges 2243 of two adjacent negative electrode 224 is controlled within 2 mm.

[0276] By controlling the spacing of the first edges 2243 of two adjacent negative electrode plates 224 within 2mm, 0≤L1≤2mm is achieved.

[0277] By making the gap between the first edges 2243 of two adjacent negative electrode plates 224 less than or equal to 2 mm, the cutting surface is made neater. On the one hand, this makes the gap between the positive and negative electrode plates smaller, which helps to shorten the ion path. On the other hand, it helps to reduce the volume occupation and improve the energy density.

[0278] Optionally, in step S400, along the first direction, the negative electrode 224 has a first edge 2243, and the distance between the first edges 2243 of two adjacent negative electrode 224 is controlled within 1 mm.

[0279] By controlling the spacing between the first edges 2243 of two adjacent negative electrode plates 224 within 1 mm, 0 ≤ L1 ≤ 1 mm is achieved.

[0280] By making the gap between the first edges 2243 of two adjacent negative electrode plates 224 less than or equal to 1 mm, the cutting surface is made neater. On the one hand, this makes the gap between the positive and negative electrode plates smaller, which helps to shorten the ion path. On the other hand, it helps to reduce the volume occupation and increase the energy density.

[0281] In some embodiments, in step S400, the distance between the cutting position of the negative electrode 224 and the separator 225 and the positive electrode 226 is controlled within 3mm to 10mm along the first direction.

[0282] By controlling the distance between the cutting position of the negative electrode 224 and the separator 225 and the positive electrode 226 to within 3mm to 10mm, so that 3mm≤L3≤10mm.

[0283] When the distance between the cutting positions of the negative electrode 224 and the separator 225 and the positive electrode 226 is greater than or equal to 3 mm, the dimension of the negative electrode 224 extending beyond the positive electrode 226 along the first direction is relatively large, which is beneficial for meeting the overhang design and reducing the risk of lithium plating. When the distance between the cutting positions of the negative electrode 224 and the separator 225 and the positive electrode 226 is less than or equal to 10 mm, the dimension of the negative electrode 224 extending beyond the positive electrode 226 along the first direction is not too large, which is beneficial for reducing the volume of the negative electrode 224 and improving the energy density. Therefore, when the distance between the cutting positions of the negative electrode 224 and the separator 225 and the positive electrode 226 is within 3 mm to 10 mm, both the overhang design and the energy density can be improved.

[0284] Optionally, in step S400, the distance between the cutting position of the negative electrode 224 and the separator 225 and the positive electrode 226 is controlled within 5mm to 8mm along the first direction.

[0285] By controlling the distance between the cutting position of the negative electrode 224 and the separator 225 and the positive electrode 226 to within 5mm to 8mm, so that 5mm≤L3≤8mm.

[0286] When the distance between the cutting positions of the negative electrode 224 and the separator 225 and the positive electrode 226 is greater than or equal to 5 mm, the dimension of the negative electrode 224 extending beyond the positive electrode 226 along the first direction is relatively large, which is beneficial for meeting the overhang design and reducing the risk of lithium plating. When the distance between the cutting positions of the negative electrode 224 and the separator 225 and the positive electrode 226 is less than or equal to 8 mm, the dimension of the negative electrode 224 extending beyond the positive electrode 226 along the first direction is not too large, which is beneficial for reducing the volume of the negative electrode 224 and improving the energy density. Therefore, when the distance between the cutting positions of the negative electrode 224 and the separator 225 and the positive electrode 226 is within 5 mm to 8 mm, both the overhang design and the energy density can be improved.

[0287] In some embodiments, in step S400, the distance between the first edge 2243 of the cut negative electrode 224 and the second edge 22512 of the isolation segment 2251 adjacent to the negative electrode 224 is controlled within 2 mm along the first direction.

[0288] By controlling the distance between the first edge 2243 of the cut negative electrode 224 and the second edge 22512 of the isolation segment 2251 adjacent to the negative electrode 224 to the nearest first edge 2243 within 2mm, 0≤L2≤2mm is achieved.

[0289] By making the distance between the first edge 2243 and the second edge 22512 less than or equal to 2mm, the edges of the negative electrode 224 and the isolation section 2251 can be made more uniform, which is beneficial to reduce volume occupation and improve energy density.

[0290] Optionally, in step S400, the distance between the first edge 2243 of the cut negative electrode 224 and the second edge 22512 of the separator 225 closest to the first edge 2243 is controlled within 1 mm along the first direction.

[0291] By controlling the distance between the first edge 2243 of the cut negative electrode 224 and the second edge 22512 of the isolation segment 2251 adjacent to the negative electrode 224 to be within 1 mm, so that 0 ≤ L2 ≤ 1 mm.

[0292] By making the distance between the first edge 2243 and the second edge 22512 less than or equal to 1 mm, the edges of the negative electrode 224 and the isolation section 2251 can be made more uniform, which is beneficial to reduce volume occupation and improve energy density.

[0293] Please refer to Figure 13, which is a schematic block diagram of an electrode assembly manufacturing method 30 provided in some embodiments of this application. In some embodiments, step S300 includes:

[0294] Step S310: At least partially fix the first extended portion 22511 of the two isolation sections 2251 adjacent to the positive electrode plate 226 by hot pressing.

[0295] By hot-pressing, the first extended portions 22511 of the two isolation sections 2251 are at least partially fixedly connected. On the one hand, this method is easier to manufacture, as it allows for the connection of the isolation sections 2251 on both sides of each positive electrode 226 in one step. On the other hand, hot pressing is less likely to damage the positive electrode 226 and the negative electrode 224, which helps to improve the reliability of the electrode assembly 22.

[0296] This application embodiment also provides a battery device 100, which includes the aforementioned battery cell 20.

[0297] This application embodiment also provides an electrical device, which includes the aforementioned battery cell 20, and the battery cell 20 is used to provide electrical energy to the electrical device.

[0298] Please refer to Figures 3 to 13 for some embodiments of this application.

[0299] This application provides a battery cell 20, which includes a housing 21 and an electrode assembly 22, with the electrode assembly 22 housed within the housing 21. The electrode assembly 22 includes a negative electrode 224, a separator 225, and a positive electrode 226, which are stacked together. The negative electrode 224 includes a negative electrode tab unit 2241 and a negative electrode body 2242, with the negative electrode tab unit 2241 connected to one side of the negative electrode body 2242. The thickness of the negative electrode body 2242 is 10 μm to 30 μm. The separator 225 has a separator segment 2251 separating the positive electrode 226 and the negative electrode 224. The separator segment 2251 has a first protruding portion 22511 extending beyond the positive electrode 226 on both sides in a first direction. The first protruding portions 22511 of two separator segments 2251 adjacent to the positive electrode 226 are at least partially fixedly connected to cover at least a portion of the edge of the positive electrode 226. The first direction is perpendicular to the stacking direction of the positive electrode 226, the separator 225, and the negative electrode 224. The thickness of the negative electrode body 2242 of the battery cell 20 is 10μm to 30μm, that is, the negative electrode 224 is an ultra-thin negative electrode. The negative electrode 224 is relatively soft, and it is not easy for the negative electrode 224 to extend beyond the positive electrode 226 in the first direction during stacking. By at least partially fixing the first protruding portion 22511 of the two isolation segments 2251 adjacent to the positive electrode 226 to cover at least a portion of the edge of the positive electrode 226, the position of the positive electrode 226 can be limited, thereby facilitating the negative electrode 224 to extend beyond the positive electrode 226 in the first direction and reducing the risk of lithium plating. On the other hand, dendrite growth can be prevented, thereby reducing the risk of short circuit and improving the reliability of the battery cell 20.

[0300] The thickness of the negative electrode body 2242 is 10μm to 20μm. The negative electrode body 2242 is thinner and the negative electrode 224 is softer. By fixing at least partially the first protruding portion 22511 of the two isolation segments 2251 adjacent to the positive electrode 226 to cover at least part of the edge of the positive electrode 226, a better effect can be achieved.

[0301] The negative electrode body 2242 includes a negative electrode current collector 22421, which is made of aluminum. The positive electrode 226 includes a positive electrode active material capable of reversibly extracting and inserting sodium ions, which includes a sodium-containing compound. Since the negative electrode current collector 22421 is made of aluminum, and the negative electrode 224 is softer, a better effect can be achieved by at least partially fixing the first protruding portion 22511 of the two adjacent insulating segments 2251 of the positive electrode 226 to cover at least a portion of the edge of the positive electrode 226.

[0302] The positive electrode 226 includes a positive electrode tab unit 2261 and a positive electrode body 2262. The positive electrode tab unit 2261 is connected to one side of the positive electrode body 2262 along a second direction. An isolation segment 2251 has second protruding portions 22513 extending beyond the positive electrode body 2262 on both sides in the second direction. At least partially, the second protruding portions 22513 of two adjacent isolation segments 2251 are fixedly connected to cover at least a portion of the edge of the positive electrode body 2262. The first direction, the second direction, and the stacking direction are mutually perpendicular. By fixing at least partially the second protruding portions 22513 of two adjacent isolation segments 2251 to cover at least a portion of the edge of the positive electrode body 2262, the position of the positive electrode 226 can be limited, thereby facilitating the negative electrode 224 to extend beyond the positive electrode 226 along the first direction and reducing the risk of lithium plating. On the other hand, it can prevent dendrites from growing around the cell, thereby reducing the risk of short circuits and improving the reliability of the cell 20.

[0303] Two isolation sections 2251 adjacent to the positive electrode 226 are connected to form a closed receiving space 227, within which the positive electrode body 2262 is housed. By housing the positive electrode body 2262 within the receiving space 227, on the one hand, the position of the positive electrode body 2262 can be limited, thereby facilitating the negative electrode 224 to extend beyond the positive electrode 226 along the first direction and reducing the risk of lithium plating. On the other hand, it can further prevent dendrite growth, thereby reducing the risk of short circuits and improving the reliability of the battery cell 20.

[0304] This application embodiment also provides an electrode assembly manufacturing method 30, which includes: step S100: providing a positive electrode 226, a separator 225, and a negative electrode 224, wherein the negative electrode 224 includes a negative electrode tab unit 2241 and a negative electrode body 2242, the negative electrode tab unit 2241 being connected to one side of the negative electrode body 2242, and the thickness of the negative electrode body 2242 being 10μm to 30μm; step S200: layering the positive electrode 226, the separator 225, and the negative electrode 224. The stacked arrangement includes an isolation segment 2251 separating the positive electrode 226 and the negative electrode 224. The isolation segment 2251 has a first overhang portion 22511 extending beyond the positive electrode 226 on both sides in a first direction, which is perpendicular to the stacking direction of the positive electrode 226, the isolation segment 225, and the negative electrode 224. Step S300: At least partially fix the first overhang portions 22511 of the two isolation segments 2251 adjacent to the positive electrode 226 to cover at least a portion of the edge of the positive electrode 226.

[0305] The thickness of the negative electrode body 2242 is equal at all locations. Since the thickness of the negative electrode body 2242 is equal at all locations, there is no need to make markings on the negative electrode body 2242.

[0306] Step S200 includes: Step S210: forming a composite electrode 228 from the positive electrode 226, the separator 225 and the negative electrode 224. The composite electrode 228 includes a plurality of positive electrode 226, which are alternately disposed on both sides of the negative electrode 224. Along the length of the composite electrode 228, the portion of the composite electrode 228 located between two adjacent positive electrode 226 is a bent section 2281; Step S220: bending the bent section 2281 so that the positive electrode 226, the separator 225 and the negative electrode 224 are stacked. By first fabricating a composite electrode 228, the bending section 2281 of the composite electrode 228 is relatively weak. The positive electrode 226, the separator 225 and the negative electrode 224 can be stacked by bending the bending section 2281, which makes the manufacturing simple and convenient. It also helps to make the negative electrode 224 extend beyond the positive electrode 226 in the first direction, reducing the risk of lithium plating.

[0307] Following step S300, the electrode assembly manufacturing method 30 further includes step S400: cutting the negative electrode 224 and the separator 225 to remove the portions of the negative electrode 224 and the separator 225 located at the bending section 2281 of the composite electrode 228. Since the negative electrode 224 is relatively soft, the bending section 2281 of the composite electrode 228 is prone to a large curvature. By cutting the negative electrode 224 and the separator 225, removing the portions of the negative electrode 224 and the separator 225 located at the bending section 2281 of the composite electrode 228, the electrode assembly 22 is shaped. On the one hand, this helps to make the interface of the electrode assembly 22 smooth, resulting in a smaller gap between the positive and negative electrodes, thereby shortening the ion path. On the other hand, it helps to reduce volume occupation and increase energy density.

[0308] Step S300 includes: Step S310: At least partially fixing the first extended portions 22511 of the two isolation sections 2251 adjacent to the positive electrode 226 by hot pressing. Fixing the first extended portions 22511 of the two isolation sections 2251 at least partially by hot pressing is convenient in manufacturing, allowing the connection of the isolation sections 2251 on both sides of each positive electrode 226 in one step. Furthermore, hot pressing is less likely to damage the positive electrode 226 and the negative electrode 224, which helps improve the reliability of the electrode assembly 22.

[0309] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

A type of battery cell, wherein, include: shell; An electrode assembly is housed within the housing. The electrode assembly includes a negative electrode, an isolator, and a positive electrode. The positive electrode, the isolator, and the negative electrode are stacked. The negative electrode includes a negative electrode tab unit and a negative electrode body. The negative electrode tab unit is connected to one side of the negative electrode body. The thickness of the negative electrode body is 10 μm to 30 μm. The separator has a separator segment separating the positive electrode and the negative electrode. The separator segment has a first extended portion extending beyond the positive electrode on both sides in a first direction. The first extended portions of two separator segments adjacent to the positive electrode are at least partially fixedly connected to cover at least a portion of the edge of the positive electrode. The first direction is perpendicular to the stacking direction of the positive electrode, the separator, and the negative electrode. According to claim 1, the battery cell, wherein, The thickness of the negative electrode body is 10μm to 20μm. According to claim 1 or 2, the battery cell, wherein, The negative electrode body includes a negative electrode current collector, and the material of the negative electrode current collector includes aluminum; The positive electrode includes a positive electrode active material capable of reversibly extracting and inserting sodium ions, and the positive electrode active material includes a sodium-containing compound. The battery cell according to any one of claims 1-3, wherein, The electrode assembly includes a plurality of negative electrode plates and a plurality of positive electrode plates. Along the stacking direction, the plurality of negative electrode plates are spaced apart, and the positive electrode plates are disposed between two adjacent negative electrode plates. The isolation section separates the positive electrode plates and the negative electrode plates. According to the battery cell of claim 4, wherein, Along the first direction, the negative electrode has a first edge, and the distance between the first edges of two adjacent negative electrodes is L1, satisfying: 0≤L1≤2mm. According to claim 5, the battery cell, wherein, 0≤L1≤1mm. The battery cell according to any one of claims 4-6, wherein, Along a first direction, the negative electrode has a first edge, and the isolation segment adjacent to the negative electrode has a second edge that is closest to the first edge. The distance between the first edge and the second edge is L2, which satisfies: 0≤L2≤2mm. According to claim 7, the battery cell, wherein, 0≤L2≤1mm. The battery cell according to any one of claims 4-8, wherein, Along the first direction, the negative electrode body extends beyond the positive electrode by a dimension L3, satisfying: 3mm≤L3≤10mm. According to claim 9, the battery cell, wherein, 5mm≤L3≤8mm. The battery cell according to any one of claims 1-10, wherein, The positive electrode includes a positive electrode tab unit and a positive electrode body, wherein the positive electrode tab unit is connected to one side of the positive electrode body along a second direction; The isolation segment has a second extended portion extending beyond the positive electrode body on both sides in the second direction. The second extended portions of two isolation segments adjacent to the positive electrode body are at least partially fixedly connected to cover at least a portion of the edge of the positive electrode body. The first direction, the second direction, and the stacking direction are perpendicular to each other. According to claim 11, the battery cell, wherein, The two isolation sections adjacent to the positive electrode are connected to form a closed receiving space, and the main body of the positive electrode is received within the receiving space. An electrode assembly, wherein, The device includes a negative electrode, an separator, and a positive electrode. The positive electrode, the separator, and the negative electrode are stacked together. The negative electrode includes a negative electrode tab unit and a negative electrode body. The negative electrode tab unit is connected to one side of the negative electrode body. The thickness of the negative electrode body is 10μm to 30μm. The separator has a separator segment separating the positive electrode and the negative electrode. The separator segment has a first extended portion extending beyond the positive electrode on both sides in a first direction. The first extended portions of two separator segments adjacent to the positive electrode are at least partially fixedly connected to cover at least a portion of the edge of the positive electrode. The first direction is perpendicular to the stacking direction of the positive electrode, the separator, and the negative electrode. The electrode assembly according to claim 13, wherein, The thickness of the negative electrode body is 10μm to 20μm. The electrode assembly according to claim 13 or 14, wherein, The negative electrode body includes a negative electrode current collector, and the material of the negative electrode current collector includes aluminum; The positive electrode includes a positive electrode active material capable of reversibly extracting and inserting sodium ions, and the positive electrode active material includes a sodium-containing compound. The electrode assembly according to any one of claims 13-15, wherein, The electrode assembly includes a plurality of negative electrode plates and a plurality of positive electrode plates. Along the stacking direction, the plurality of negative electrode plates are spaced apart, and the positive electrode plates are disposed between two adjacent negative electrode plates. The isolation section separates the positive electrode plates and the negative electrode plates. The electrode assembly according to claim 16, wherein, Along the first direction, the negative electrode has a first edge, and the distance between the first edges of two adjacent negative electrodes is L1, satisfying: 0≤L1≤2mm. The electrode assembly according to claim 17, wherein, 0≤L1≤1mm. The electrode assembly according to any one of claims 16-18, wherein, Along a first direction, the negative electrode has a first edge, and the isolation segment adjacent to the negative electrode has a second edge that is closest to the first edge. The distance between the first edge and the second edge is L2, which satisfies: 0≤L2≤2mm. The electrode assembly according to claim 19, wherein, 0≤L2≤1mm. The electrode assembly according to any one of claims 16-20, wherein, Along the first direction, the negative electrode body extends beyond the positive electrode by a dimension L3, satisfying: 3mm≤L3≤10mm. The electrode assembly according to claim 21, wherein, 5mm≤L3≤8mm. A method for manufacturing an electrode assembly, wherein, include: Step S100: Provide a positive electrode, an separator, and a negative electrode. The negative electrode includes a negative electrode tab unit and a negative electrode body. The negative electrode tab unit is connected to one side of the negative electrode body. The thickness of the negative electrode body is 10μm to 30μm. Step S200: The positive electrode, the separator, and the negative electrode are stacked together. The separator has a separator section that separates the positive electrode and the negative electrode. The separator section has a first overhang portion that extends beyond the positive electrode on both sides in a first direction. The first direction is perpendicular to the stacking direction of the positive electrode, the separator, and the negative electrode. Step S300: At least partially fix the first extended portion of the two isolation segments adjacent to the positive electrode to cover at least a portion of the edge of the positive electrode. The method for manufacturing an electrode assembly according to claim 23, wherein, In step S100, the thickness of the negative electrode body is 10μm to 20μm. The method for manufacturing an electrode assembly according to claim 24, wherein, In step S200, the difference between the maximum thickness of the negative electrode body and the minimum thickness of the negative electrode is less than or equal to 2 μm. The method for manufacturing an electrode assembly according to claim 25, wherein, The thickness of the negative electrode body is equal at all locations. The method for manufacturing an electrode assembly according to any one of claims 23-26, wherein, Step S200 includes: Step S210: The positive electrode, the separator, and the negative electrode are made into a composite electrode. The composite electrode includes multiple positive electrodes, which are alternately arranged on both sides of the negative electrode. Along the length of the composite electrode, the portion of the composite electrode located between two adjacent positive electrodes is a bent section. Step S220: Bend the bent section to stack the positive electrode, the separator, and the negative electrode. The method for manufacturing an electrode assembly according to claim 27, wherein, After step S300, the electrode assembly manufacturing method further includes: Step S400: Cut the negative electrode and the separator to remove the portion of the negative electrode and the separator located in the bent section of the composite electrode. The method for manufacturing an electrode assembly according to claim 28, wherein, In step S400, along the first direction, the negative electrode sheet has a first edge, and the distance between the first edges of two adjacent negative electrode sheets is controlled within 2 mm. The method for manufacturing an electrode assembly according to claim 29, wherein, In step S400, along the first direction, the negative electrode sheet has a first edge, and the distance between the first edges of two adjacent negative electrode sheets is controlled within 1 mm. The method for manufacturing an electrode assembly according to any one of claims 28-30, wherein, In step S400, along the first direction, the distance between the cutting position of the negative electrode and the separator and the positive electrode is controlled within 3mm to 10mm. The method for manufacturing an electrode assembly according to claim 31, wherein, In step S400, along the first direction, the distance between the cutting position of the negative electrode and the separator and the positive electrode is controlled within 5mm to 8mm. The method for manufacturing an electrode assembly according to any one of claims 28-32, wherein, In step S400, along the first direction, the distance between the first edge of the cut negative electrode sheet and the second edge of the isolation segment adjacent to the negative electrode sheet that is closest to the first edge is controlled within 2 mm. The method for manufacturing an electrode assembly according to claim 33, wherein, In step S400, along the first direction, the distance between the first edge of the cut negative electrode sheet and the second edge of the separator closest to the first edge is controlled within 1 mm. The method for manufacturing an electrode assembly according to any one of claims 23-34, wherein, Step S300 includes: Step S310: At least partially fix the first extended portion of the two isolation sections adjacent to the positive electrode plate by hot pressing. A battery device, wherein, Includes the battery cell according to any one of claims 1-12. An electrical device, wherein, Includes a battery cell according to any one of claims 1-12, the battery cell being used to provide electrical energy to the electrical device.

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