Battery cell

Abstract

The utility model discloses a battery cell, which is formed by winding after a positive plate and a negative plate are laminated, the negative plate comprises a negative current collector and two first active material layers, the two first active material layers are respectively arranged on two sides of the negative current collector, and the first active material layers completely cover the negative current collector; the positive plate comprises a positive current collector and a second active material layer, the positive current collector comprises a first section, a second section, a third section and a fourth section which are sequentially connected in the length direction, the end, away from the second section, of the first section is a winding starting point of the positive current collector, and the end, away from the third section, of the fourth section is a winding ending point of the positive current collector; the first section and the fourth section are not provided with the second active material layer, the two sides of the second section are provided with the second active material layer, and the side, close to the negative plate, of the third section is provided with the second active material layer. The battery cell provided by the utility model can have relatively high safety.

Description

Technical Field

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

[0002] In related technologies, battery cells can be manufactured using a winding process. The principle of the winding process is to sequentially wind and extrude the pre-treated positive electrode sheet, separator, and negative electrode sheet using fixed winding needles. Specifically, in the design of the negative electrode sheet, the winding head of the negative electrode sheet has a single-sided sheet structure. Because the winding head of the negative electrode sheet is a single-sided sheet, during the rolling of the negative electrode sheet, the stress difference between the coated and uncoated areas causes the single-sided sheet area to easily curl up. During the winding process, the negative electrode sheet is prone to wrinkling, powder shedding, and folding, which can lead to lithium plating in the battery cell and reduce its safety. Utility Model Content

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a battery cell that has high safety.

[0004] According to an embodiment of the present invention, the battery cell is formed by stacking and winding a positive electrode sheet and a negative electrode sheet. The negative electrode sheet includes a negative current collector and two first active material layers, which are respectively disposed on both sides of the negative current collector, and the first active material layers completely cover the negative current collector. The positive electrode sheet includes a positive current collector and a second active material layer. The positive current collector includes a first segment, a second segment, a third segment, and a fourth segment connected sequentially along the length direction. The end of the first segment away from the second segment is the winding start point of the positive current collector, and the end of the fourth segment away from the third segment is the winding end point of the positive current collector. The first segment and the fourth segment do not have the second active material layer disposed on either side of the second segment, and the third segment has the second active material layer disposed on the side closer to the negative electrode sheet.

[0005] The battery cell according to the embodiments of this utility model has at least the following beneficial effects: two first active material layers are respectively connected to both sides of the negative electrode current collector, and the first active material layers completely cover the negative electrode current collector. Therefore, the negative electrode sheet of the battery cell of this application can effectively avoid the folding and powder shedding problems caused by the single-sided sheet structure, thereby effectively improving the safety of the battery cell. Specifically, the battery cell can have high safety.

[0006] According to some embodiments of the present invention, the battery cell has two second active material layers, which are respectively a first part and a second part. Along the winding direction of the battery cell, the length of the first part is less than the length of the second part. The length of the first active material layer is L1, the length of the first part is L2, the thickness of the battery cell is h, and the width of the battery cell is C, where 2mm≤L1-L2-(Ch)≤8mm.

[0007] According to some embodiments of the present invention, the two second active material layers are respectively a first part and a second part. Along the winding direction of the battery cell, the length of the first part is less than the length of the second part. The length of the first active material layer is L1, the length of the second part is L3, the thickness of the battery cell is h, and the width of the battery cell is C, where 2mm≤L1+(Ch)-L3≤8mm.

[0008] According to some embodiments of the present invention, the negative current collector of the battery cell includes a first end and a second end. The first end is the starting point of the winding of the negative current collector, and the second end is the ending point of the winding of the negative current collector. A center line is defined in the width direction of the battery cell. The first end and the first segment are located on both sides of the center line, respectively. The closest distance between the first end and the positive electrode sheet along the width direction of the battery cell is C1, where 0.5mm≤C1≤6mm.

[0009] According to some embodiments of the present invention, the battery cell further includes a first protective layer, the negative current collector includes a first end and a second end, the first end is the starting point of the winding of the negative current collector, the second end is the ending point of the winding of the negative current collector, the positive electrode sheet is provided with a groove, the groove is located in the innermost layer of the battery cell, the opening of the groove faces the first end, and the first protective layer covers the groove.

[0010] According to some embodiments of the present invention, the distance between the first end and the edge of the groove along the width direction of the battery cell is C2, where 0.5mm≤C2≤6mm.

[0011] According to some embodiments of the present invention, the size of the first segment of the battery cell along the width direction of the battery cell is C4, where 1.5mm≤C4≤4mm.

[0012] According to some embodiments of the present invention, in the battery cell along the width direction of the battery cell, the closest distance between the end of the second segment near the first segment and the negative electrode is C3, where 2.0mm≤C3≤6mm.

[0013] According to some embodiments of the present invention, the battery cell has a diameter of 0.5mm ≤ C3-C4 ≤ 5mm.

[0014] According to some embodiments of the present invention, the battery cell further includes a second protective layer connected to the negative electrode sheet. The second protective layer at least partially covers the end of the first segment away from the second segment. Along the width direction of the battery cell, the closest distance between the second protective layer and the second active material layer on the second segment is C6, where C4 > C6 ≥ 1.5 mm.

[0015] According to some embodiments of the present invention, the cell thickness is 0.5mm≤C4-C6≤1.5mm.

[0016] According to some embodiments of the present invention, the first protective layer also covers the edge of the groove. Along the width direction of the battery cell, the dimension of the first protective layer covering the edge of the groove is C5, where 0.5mm≤C5≤5mm.

[0017] According to some embodiments of the present invention, the width of the groove in the battery cell is T1, the width of the first protective layer is T2, 1mm≤T2-T1≤10mm, and T1=2*(C1+C2).

[0018] According to some embodiments of the present invention, the battery cell further includes a second protective layer connected to the negative electrode sheet, and the second protective layer at least partially covers the end of the first segment away from the second segment.

[0019] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0021] Figure 1 This is a schematic diagram of a battery cell according to some embodiments of the present invention;

[0022] Figure 2 This is a partial schematic diagram of a battery cell according to some embodiments of the present invention;

[0023] Figure 3 This is a schematic diagram of the negative electrode plate in the battery cell of some embodiments of this utility model;

[0024] Figure 4 This is a schematic diagram of the positive electrode plate in the battery cell of the first embodiment of this utility model;

[0025] Figure 5 This is a schematic diagram of the positive electrode plate in the battery cell of the second embodiment of this utility model.

[0026] Figure label:

[0027] Battery cell 10, positive electrode 100, positive current collector 110, first section 120, second section 130, third section 140, fourth section 150, second active material layer 200, first part 210, second part 220, groove 230, ceramic layer 240, negative electrode 300, negative current collector 310, first end 320, second end 330, first active material layer 400, intermediate line 500, first protective layer 600, second protective layer 700. Detailed Implementation

[0028] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0029] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0030] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0031] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0032] In the description of this utility model, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0033] The battery can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0034] A battery typically consists of a cell. The cell includes a positive electrode, a negative electrode, and a separator. During charging and discharging, active ions (such as lithium ions) move back and forth between the positive and negative electrodes, inserting and releasing. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through.

[0035] In some implementations, the battery cell has a wound structure. The positive and negative electrode plates are wound into a wound structure.

[0036] In some implementations, the battery cell has a laminated structure.

[0037] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0038] 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.

[0039] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0040] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0041] As an example, the separators can be continuously arranged, either by folding or rolling between any adjacent positive or negative electrode plates.

[0042] In some implementations, the battery cell can be cylindrical, flat, or polygonal, etc.

[0043] In some implementations, the battery cell is provided with tabs that allow current to be drawn out of the cell. The tabs include a positive tab and a negative tab.

[0044] In some embodiments, the battery may include a casing. The casing is used to encapsulate components such as the battery cell and electrolyte. The casing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0045] As an example, the battery can be a cylindrical battery, a prismatic battery, a pouch battery, or a battery of other shapes. Prismatic batteries include, but are not limited to, square-shell batteries, blade-shaped batteries, and multi-prismatic batteries, such as hexagonal prismatic batteries.

[0046] The battery mentioned in the embodiments of this application refers to a single physical module that includes one or more batteries to provide higher voltage and capacity.

[0047] In some embodiments, the battery can be a battery module, and when there are multiple batteries, the multiple batteries are arranged and fixed to form a battery module.

[0048] In some embodiments, the battery may be a battery pack, which includes a housing and a battery, with the battery or battery module housed within the housing.

[0049] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0050] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0051] In related technologies, battery cells can be manufactured using a winding process. The principle of the winding process is to sequentially wind and extrude pre-treated positive electrode sheets, separators, and negative electrode sheets using fixed winding needles. Specifically, in the design of the negative electrode sheet, the winding head of the negative electrode sheet has a single-sided sheet structure. Because the winding head of the negative electrode sheet is a single-sided sheet, during the rolling process, the stress difference between the coated and uncoated areas causes the single-sided sheet area to easily curl up. During the winding process, the negative electrode sheet is prone to wrinkling, powder shedding, and folding, which can lead to lithium plating in the battery cell, reducing its safety. Therefore, this application proposes a battery cell.

[0052] Please refer to Figure 1In some embodiments, the battery cell 10 is formed by stacking and winding a positive electrode 100 and a negative electrode 300. A separator is provided between the positive electrode 100 and the negative electrode 300. The winding of the positive electrode 100 and the negative electrode 300 into the battery cell 10 can be completed by a winding process, which is prior art and will not be described further here. For the negative electrode 300, please refer to... Figure 3 The negative electrode 300 includes a negative current collector 310 and two first active material layers 400. The negative current collector 310 can be copper foil, and the first active material layers 400 can be negative active materials. The two first active material layers 400 are respectively disposed on both sides of the negative current collector 310, and the first active material layers 400 completely cover the negative current collector 310. That is, the first active material layers 400 completely cover the negative current collector 310, and there are no empty foil areas on the negative current collector 310. Specifically, the two first active material layers 400 are respectively connected to both sides of the negative current collector 310, and the first active material layers 400 completely cover the negative current collector 310. Therefore, the negative electrode 300 of the battery cell 10 of this application can effectively avoid the folding and powder shedding problems caused by the single-sided sheet structure, thereby effectively improving the safety of the battery cell 10. Specifically, the battery cell 10 can have high safety. In addition, the negative electrode 300 also eliminates the zebra coating process, which can effectively improve manufacturing efficiency.

[0053] Furthermore, the structure of the negative electrode 300 has been described above; the structure of the positive electrode 100 will be described below. Please refer to... Figure 1 and Figure 4In some embodiments, the positive electrode 100 includes a positive current collector 110 and a second active material layer 200. The positive current collector 110 may be an aluminum foil. The second active material layer 200 may be a positive active material. The positive current collector 110 includes a first segment 120, a second segment 130, a third segment 140, and a fourth segment 150 connected sequentially along its length. That is, the two ends of the second segment 130 are connected to the first segment 120 and the third segment 140, respectively, and the two ends of the third segment 140 are connected to the second segment 130 and the fourth segment 150, respectively. The end of the first segment 120 away from the second segment 130 is the starting point for winding the positive current collector 110, and the end of the fourth segment 150 away from the third segment 140 is the ending point for winding the positive current collector 110. The starting point and the ending point refer to the fact that when the positive electrode 100 is being wound, the positive current collector 110 is also being wound, and at this time, one end of the positive electrode 100 serves as the starting point for winding. After winding, one end of both the positive electrode 100 and the negative electrode 300 at the starting point of winding are located in the innermost layer of the cell 10. Furthermore, the second active material layer 200 can be disposed on the positive current collector 110 in the following ways: no second active material layer 200 is disposed on the first segment 120 and the fourth segment 150; the second active material layer 200 is disposed on both sides of the second segment 130; and the second active material layer 200 is disposed on the side of the third segment 140 closest to the negative electrode 300.

[0054] Further, please refer to Figure 1 , Figure 3 and Figure 4 In some embodiments, the two second active material layers 200 are a first part 210 and a second part 220, respectively. Along the winding direction of the cell 10, the length of the first part 210 is less than the length of the second part 220. The dimension of the first part 210 in the winding direction of the cell 10 is its length, and the dimension of the second part 220 in the winding direction of the cell 10 is its length. The length of the first active material layer 400 is L1, the length of the first part 210 is L2, the thickness of the cell 10 is h, and the width of the cell 10 is C, where 2mm ≤ L1 - L2 - (Ch) ≤ 8mm. Specifically, L1 - L2 - (Ch) can be equal to 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, or 8mm. When L1 - L2 - (Ch) is less than 2mm, the length of the first active material layer 400 is relatively small, which may lead to lithium plating in the cell 10. When L1-L2-(Ch) is greater than 8mm, the length of the first active material layer 400 is relatively large. This may lead to a mismatch between the amount of positive active material layer and the mass of negative active material. Although the amount of the first active material layer 400 is large, it does not increase the actual charge of the cell 10, thus resulting in a lower energy density of the cell 10.

[0055] Further, please refer to Figure 1 , Figure 3 and Figure 4 In some embodiments, the two second active material layers 200 are a first part 210 and a second part 220, respectively. Along the winding direction of the cell 10, the length of the first part 210 is less than the length of the second part 220. The length of the first active material layer 400 is L1, the length of the second part 220 is L3, the thickness of the cell 10 is h, and the width of the cell 10 is C, where 2mm ≤ L1 + (Ch) - L3 ≤ 8mm. Specifically, L1 + (Ch) - L3 can be equal to 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, or 8mm. When L1 + (Ch) - L3 is less than 2mm, the length of the first active material layer 400 is relatively small, which may lead to lithium plating in the cell 10. When L1+(Ch)-L3 is greater than 8mm, the length of the first active material layer 400 is relatively large. This may lead to a mismatch between the amount of positive active material layer and the mass of negative active material. Although the amount of the first active material layer 400 is large, it does not increase the actual charge of the cell 10, thus resulting in a lower energy density of the cell 10.

[0056] Further, please refer to Figure 1 and Figure 2 In some embodiments, the negative current collector 310 includes a first end 320 and a second end 330. The first end 320 is the starting point for winding the negative current collector 310, and the second end 330 is the ending point for winding the negative current collector 310. That is, when winding the negative electrode sheet 300, winding begins from the first end 320. A center line 500 is defined in the width direction of the cell 10. The center line 500 is a virtual line used to conveniently divide the cell 10 into two halves in the width direction. The first end 320 and the first segment 120 are located on both sides of the center line 500, respectively. The closest distance between the first end 320 and the positive electrode sheet 100 along the width direction of the cell 10 is C1, where 0.5mm ≤ C1 ≤ 6mm. Specifically, the first end 320 is located in the innermost layer of the cell 10, that is, the first end 320 is located in the innermost part of the cell 10. C1 can be equal to 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm, or 6mm. When C1 is less than 0.5mm, the distance between the first end 320 and the positive electrode 100 is too close, which may cause the first end 320 to puncture the positive electrode 100, thus posing a safety hazard to the cell 10. In addition, the close distance between the first end 320 and the positive electrode 100 may also make it inconvenient to wind the positive electrode 100 and the negative electrode 300, reducing processing efficiency. When C1 is greater than 6mm, the larger C1 is, the shorter the length of the negative electrode 300, which will result in a lower energy density of the cell 10.

[0057] Further, please refer to Figure 1 and Figure 2 In some embodiments, the battery cell 10 further includes a first protective layer 600. The negative electrode current collector 310 includes a first end 320 and a second end 330. The first end 320 is the starting point for winding the negative electrode current collector 310, and the second end 330 is the ending point for winding the negative electrode current collector 310. That is, when winding the negative electrode sheet 300, winding begins from the first end 320. The positive electrode sheet 100 is provided with a groove 230. Specifically, the groove 230 can be formed by completely removing or partially thinning the second active material layer 200, thereby either creating the groove 230 on the second active material layer 200, or by having the second active material layer 200 and the positive electrode current collector 110 jointly define the groove 230. The groove 230 is located in the innermost layer of the battery cell 10, and the opening of the groove 230 faces the first end 320. The first protective layer 600 covers the groove 230. The first protective layer 600 can be adhesive tape or an adhesive layer, and it can be adhered to the groove wall of the groove 230. Specifically, the opening of the groove 230 faces the first end 320, and after the first protective layer 600 is located in the groove 230, the first end 320 can be wrapped by the first protective layer 600. This can effectively avoid the safety hazards caused by burrs on the first end 320, thereby improving the safety of the battery cell 10.

[0058] Further, please refer to Figure 1 and Figure 2 In some embodiments, the distance between the first end 320 and the edge of the groove 230 along the width direction of the cell 10 is C2, where 0.5mm ≤ C2 ≤ 6mm. Specifically, C2 can be equal to 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm, or 6mm. When C2 is less than 0.5mm, the size of the groove 230 is small, which results in a poor effect of the first protective layer 600 wrapping the first end 320, or the first protective layer 600 may be partially located in the groove 230, resulting in poor flatness of the cell 10. When C2 is greater than 6mm, the greater the distance between the edge of the groove 230 and the first end 320, the larger the size of the groove 230, which results in a smaller amount of active material in the positive electrode 100 and a lower energy density of the cell 10.

[0059] Furthermore, the middle portion of the first protective layer 600 can be disposed within the groove 230, and the edge of the first protective layer 600 can cover the edge of the groove 230 (i.e., cover the second active material layer 200). That is, the first protective layer 600 also covers the edge of the groove 230. Along the width direction of the cell 10, the dimension of the first protective layer 600 covering the edge of the groove 230 is C5, where 0.5mm ≤ C5 ≤ 5mm, and C5 = 0.5mm, 1mm, 2mm, 3mm, 4mm, or 5mm. Specifically, after the edge of the first protective layer 600 covers the second active material, the dimension it covers in the width direction of the cell 10 is not less than 0.5mm and not more than 5mm. If C5 is greater than 5mm, it will result in a lower energy density of the cell 10; if C5 is less than 0.5mm, it will result in poor adhesion to the groove 230. In addition, to improve the flatness of the cell 10, the second active material layer 200 can be cut off. In this way, even if the edge of the first protective layer 600 covers the second active material layer 200, the flatness of the cell 10 is still relatively high.

[0060] Further, please refer to Figure 1 and Figure 2 In some embodiments, along the width direction of the cell 10, the closest distance between the end of the second segment 130 closest to the first segment 120 and the negative electrode 300 is C3, where 2.0mm ≤ C3 ≤ 6mm. Specifically, C3 can be equal to 2mm, 3mm, 4mm, 5mm, or 6mm. When C3 is less than 2mm, the first segment 120 is either too short or too close to the negative electrode 300, both of which make the cell 10 inconvenient to process. When C3 is greater than 6mm, this may result in a lower energy density of the cell 10.

[0061] Further, please refer to Figure 1 and Figure 2 In some embodiments, the first segment 120 has a dimension of C4 along the width direction of the cell 10, where 1.5mm ≤ C4 ≤ 4mm. Specifically, C4 can be equal to 1.5mm, 2mm, 2.5mm, 3mm, or 4mm. When C4 is less than 2mm, the first segment 120 is too short, making the cell 10 difficult to process. When C4 is greater than 4mm, the first segment 120 is too long, resulting in material waste. In some embodiments, 0.5mm ≤ C3 - C4 ≤ 5mm. C3 - C4 can be equal to 0.5mm, 1mm, 2mm, 3mm, 4mm, or 5mm. If C3 - C4 is less than 0.5mm, the first segment 120 may puncture the negative electrode 300; if C3 - C4 is greater than 5mm, it may result in a lower energy density of the cell 10.

[0062] Further, please refer to Figure 1 and Figure 2 In some embodiments, the battery cell 10 further includes a second protective layer 700, which is connected to the negative electrode 300 and located at the innermost layer of the battery cell 10. The second protective layer 700 at least partially covers the end of the first segment 120 away from the second segment 130. Specifically, the second protective layer 700 can be an adhesive layer or adhesive tape. The second protective layer 700 can be disposed at the bend of the battery cell 10 and then abut against the positive electrode 100, which can effectively solve the safety hazards caused by burrs at the end of the first segment 120.

[0063] In some embodiments, the battery cell 10 further includes a second protective layer 700, which is connected to the negative electrode 300. The second protective layer 700 at least partially covers the end of the first segment 120 away from the second segment 130. Along the width direction of the battery cell 10, the closest distance between the second protective layer 700 and the second active material layer 200 on the second segment 130 is C6, where C4 > C6 ≥ 1.5 mm. Specifically, C4 > C6 effectively prevents the second protective layer 700 from extending onto the positive electrode 100. If C6 is less than 1.5 mm, the second protective layer 700 may not completely cover the end of the first segment 120. In other embodiments, 0.5 mm ≤ C4 - C6 ≤ 1.5 mm. Specifically, C4 - C6 is equal to 0.5 mm, 0.1 mm, 0.5 mm, 0.8 mm, 0.9 mm, 1 mm, 1.2 mm, 1.4 mm, or 1.5 mm. When C4-C6 is less than 0.5mm, this will result in the second protective layer 700 being too long; when C4-C6 is greater than 1.5mm, this will result in the cell 10 having a lower energy density.

[0064] Furthermore, the distance between the second protective layer 700 and the second segment 130 in the width direction of the cell 10 can be 2mm to 4mm. Among them, C4 is larger than this dimension, and the difference between the two can be 0.5mm to 1.5mm, such as 0.5mm, 1mm, 1.2mm or 1.5mm.

[0065] Further, please refer to Figures 1 to 5The width of the groove 230 is T1, and the width of the first protective layer 600 is T2, where 1mm ≤ T2 - T1 ≤ 10mm, and T1 = 2*(C1 + C2). For example, T2 - T1 = 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, or 10mm. Specifically, the width of the first protective layer 600 is greater than the width of the groove 230, which allows the first protective layer 600 to completely cover the groove 230, improving the safety of the cell 10. The positive electrode 100 also includes a ceramic layer 240. Both the ceramic layer 240 and the second active material layer 200 are connected to the positive current collector 110, wherein the ceramic layer 240 and the second active material layer 200 are arranged along the width direction of the positive current collector 110. Along the width direction of the positive electrode 100, the size of the second active material layer 200 is D1, and the size of the ceramic layer 240 is D2. Along the width direction of the negative electrode 300, the size of the first active material is D3. 0.5mm ≤ D3 - D1 ≤ 10mm, for example, D3 - D1 = 0.5mm, 2mm, 3mm, 4mm, 5mm, or 10mm. 0mm ≤ D2 ≤ 5mm, for example, D2 = 0mm, 1mm, 2mm, 3mm, or 4mm. It should be noted that when D2 equals zero, there is no ceramic layer 240 on the positive electrode 100.

[0066] Furthermore, the positive and negative tabs of the battery cell 10 in this application can be provided in multiples, or only one positive tab and one negative tab can be provided respectively, and the positive tab is located in the middle of the positive electrode plate 100 and the negative tab is located in the middle of the negative electrode plate 300.

[0067] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. An electric cell, characterized by, The negative electrode sheet is formed by laminating and winding a positive electrode sheet and a negative electrode sheet, the negative electrode sheet includes a negative electrode current collector and two first active material layers, the two first active material layers are respectively arranged on two sides of the negative electrode current collector, and the first active material layers are entirely covered on the negative electrode current collector; The positive electrode sheet includes a positive electrode current collector and a second active material layer, the positive electrode current collector includes a first segment, a second segment, a third segment and a fourth segment which are sequentially connected along a length direction, one end of the first segment away from the second segment is a winding starting point of the positive electrode current collector, one end of the fourth segment away from the third segment is a winding ending point of the positive electrode current collector, the first segment and the fourth segment are not provided with the second active material layer, the second segment is provided with the second active material layer on both sides, and the third segment is provided with the second active material layer on a side close to the negative electrode sheet.

2. The electric cell of claim 1, wherein, The two second active material layers are respectively a first part and a second part, along a winding direction of the battery cell, a length of the first part is less than a length of the second part, a length of the first active material layer is L1, the length of the first part is L2, a thickness of the battery cell is h, and a width of the battery cell is C, 2mm≤L1-L2-(C-h)≤8mm.

3. The electric cell of claim 1, wherein, The two second active material layers are respectively a first part and a second part, along a winding direction of the battery cell, a length of the first part is less than a length of the second part, a length of the first active material layer is L1, the length of the second part is L3, a thickness of the battery cell is h, and a width of the battery cell is C, 2mm≤L1+(C-h)-L3≤8mm.

4. The electric cell of claim 1, wherein, The negative electrode current collector includes a first end and a second end, the first end is a winding starting point of the negative electrode current collector, the second end is a winding ending point of the negative electrode current collector, an intermediate line is defined in a width direction of the battery cell, and the first end and the first segment are respectively located on two sides of the intermediate line, wherein, along the width direction of the battery cell, a closest distance between the first end and the positive electrode sheet is C1, 0.5mm≤C1≤6mm.

5. The electric cell of claim 4, wherein, The battery cell further includes a first protective layer, the negative electrode current collector includes a first end and a second end, the first end is a winding starting point of the negative electrode current collector, the second end is a winding ending point of the negative electrode current collector, the positive electrode sheet is provided with a groove, the groove is located in an innermost layer of the battery cell, an opening of the groove faces the first end, and the first protective layer covers the groove.

6. The electric cell of claim 5, wherein, Along the width direction of the battery cell, a distance between the first end and an edge of the groove is C2, 0.5mm≤C2≤6mm.

7. The electric cell of claim 1, wherein, Along the width direction of the battery cell, a size of the first segment is C4, 1.5mm≤C4≤4mm.

8. The electric cell of claim 7, wherein, Along the width direction of the battery cell, a closest distance between one end of the second segment close to the first segment and the negative electrode sheet is C3, 2.0mm≤C3≤6mm.

9. The electric cell of claim 8, wherein, 0.5mm≤C3-C4≤5mm.

10. The electric cell of claim 7, wherein, The electric core further comprises a second protective layer connected to the negative electrode sheet, the second protective layer at least partially covers one end of the first section away from the second section, and the closest distance between the second protective layer and the second active material layer on the second section in the width direction of the electric core is C6, C4>C6≥1.5mm.

11. The electric cell of claim 10, wherein, 0.5mm≤C4-C6≤1.5mm.

12. The electric cell of claim 6, wherein, The first protective layer further covers the edge of the groove, and the size of the first protective layer covering the edge of the groove in the width direction of the electric core is C5, 0.5mm≤C5≤5mm.

13. The electric cell of claim 12, wherein, The width of the groove is T1, the width of the first protective layer is T2, 1mm≤T2-T1≤10mm, and T1=2*(C1+C2).

14. The electric cell of claim 1, wherein, The electric core further comprises a second protective layer connected to the negative electrode sheet, the second protective layer at least partially covers one end of the first section away from the second section.

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