Winding cell and lithium battery
Patent Information
- Application Number
- CN202521601969.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-29
- Publication Date
- 2026-09-04
- Estimated Expiration
- 2035-07-29
AI Technical Summary
正负极的overhang区域指的是负极活性涂层在投影方向上超出正极涂层的边缘区域，如图4所示，这样会导致卷芯头部的正负极的overhang区域存在厚台阶，以造成卷绕电芯平整度较差，导致卷绕电芯在长循环过程中容易出现界面问题导致电芯性能失效
[0025] Because the adhesive layer is located between the empty foil area of the negative electrode head and the single-layer fabric area of the head, and in the arc area of the winding head of the core body; in the projection direction of the thickness of the core body, the first end of the adhesive layer is located between the inner end of the positive electrode coating and the arc area of the winding head of the core body, so that the added adhesive layer compensates for the thickness of the positive and negative electrode overhang areas of the core head, improves the flatness of the wound cell, and reduces the risk of performance failure of the wound cell. In addition, the adhesive layer has high flexibility, making it less prone to wrinkling or cracking during winding, thereby effectively improving the flatness of the wound cell. The wound cell disclosed herein does not require coating, which avoids material waste; at the same time, it does not require increasing the formation pressure, which can effectively prevent the problem of poor electrolyte wetting due to increased pressure affecting the electrical performance of the wound cell.
Smart Images
Figure CN224720878U_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of wound battery cell technology, and in particular to a wound battery cell and a lithium battery. Background Technology
[0002] Based on the mounting position of the tabs, wound cells can be divided into head-mounted wound cells and center-mounted wound cells. During the manufacturing process of center-mounted wound cells, an overhang area for the positive and negative electrodes is usually reserved at the head of the cell to prevent lithium plating. The overhang area refers to the region where the negative electrode active coating extends beyond the edge of the positive electrode coating in the projected direction. Figure 4 As shown, this results in thick steps in the overhang area of the positive and negative electrodes at the head of the winding core, leading to poor flatness of the wound cell. This makes the wound cell prone to interface problems during long cycles, causing cell performance failure.
[0003] Currently, there are two common improvement methods. One is to increase the folding of the negative electrode A-side or B-side in the overhang region of the positive and negative electrodes, such as... Figure 5 The method of compensating for the thickness of the overhang region of the positive and negative electrodes can improve the flatness of the wound cell; however, this can lead to powder shedding in the folded part, resulting in poor K value and waste of coating; and since the thickness compensation in the folded part is small due to the lack of lithium intercalation in the negative electrode, it cannot effectively improve the flatness of the wound cell; secondly, by increasing the formation pressure, the difference in thickness steps of the overhang region of the positive and negative electrodes can be reduced; however, this can lead to poor electrolyte wetting, thus affecting the electrical performance of the wound cell. Utility Model Content
[0004] The purpose of this disclosure is to overcome the shortcomings of the prior art and provide a wound cell and lithium battery that can improve the flatness of the wound cell by using only an adhesive paper layer without the need for coatings or increased formation pressure.
[0005] The purpose of this disclosure is achieved through the following technical solution:
[0006] A wound battery cell, comprising:
[0007] The core body includes a positive electrode sheet, a negative electrode sheet, and a separator wound together.
[0008] The positive electrode sheet includes a positive electrode current collector and a positive electrode coating layer. The positive electrode coating layer is respectively disposed on both sides of the positive electrode current collector, and the end of the positive electrode coating layer located at the winding start end of the positive electrode sheet is the inner end.
[0009] The negative electrode sheet includes a negative electrode current collector and a negative electrode coating layer, the negative electrode coating layer being disposed on both sides of the negative electrode current collector; the negative electrode sheet has a negative electrode head empty foil area and a head single fabric area; the negative electrode head empty foil area is located at the winding start end of the negative electrode sheet; the head single fabric area is connected to the negative electrode head empty foil area, the negative electrode coating layer is disposed on the outer side of the winding of the negative electrode current collector in the head single fabric area, and the inner side of the winding of the negative electrode current collector in the head single fabric area is exposed to the negative electrode coating layer; in the projection direction of the thickness of the core body, the negative electrode coating layer of the negative electrode sheet covers and extends beyond the positive electrode coating of the positive electrode sheet;
[0010] An adhesive tape layer is disposed between the empty foil area of the negative electrode head and the single fabric area of the head, and is located in the arc area of the winding head of the core body; in the projection direction of the thickness of the core body, the first end of the adhesive tape layer is located between the inner end of the positive electrode coating and the arc area of the winding head of the core body.
[0011] In one embodiment, the outer arc region of the empty foil area of the negative electrode head is a first arc region, and the inner arc region of the empty foil area of the negative electrode head is a second arc region, and the adhesive layer covers the first arc region or the second arc region.
[0012] In one embodiment, in the direction perpendicular to the projection of the thickness of the core body, the first end of the adhesive layer is flush with the inner end.
[0013] The second end of the adhesive tape layer abuts against the negative electrode coating layer.
[0014] In one embodiment, the first arc region or the second arc region includes a first horizontal portion, a bent portion and a second horizontal portion connected in sequence. The starting end of the first horizontal portion abuts against the negative electrode coating layer, and the ending end of the second horizontal portion is flush with the inner end in the vertical projection direction of the thickness of the core body.
[0015] The adhesive tape layer includes a first straight section, a curved section, and a second straight section connected in sequence. The first straight section covers the first horizontal portion, the curved section covers the bent portion, and the second straight section covers the second horizontal portion.
[0016] In one embodiment, the positive electrode sheet further forms a positive electrode head empty foil area, the positive electrode current collector of the positive electrode head empty foil area is connected and exposed at the inner end, the arc area is the arc area on the outer side of the positive electrode current collector of the positive electrode head empty foil area is the third arc area, the arc area on the inner side of the positive electrode current collector of the positive electrode head empty foil area is the fourth arc area, and the adhesive paper layer covers the third arc area or the fourth arc area.
[0017] In one embodiment, in the direction perpendicular to the projection of the thickness of the core body, the first end of the adhesive layer is flush with the inner end.
[0018] The second end of the adhesive tape layer abuts against the positive electrode coating layer.
[0019] In one embodiment, the thickness of the adhesive tape layer accounts for 60% to 100% of the thickness of the positive electrode coating layer or the negative electrode coating layer.
[0020] In one embodiment, the adhesive layer includes a substrate and an adhesive layer connected together; and / or,
[0021] The thickness of the adhesive layer accounts for 60% to 80% of the thickness of the adhesive paper layer.
[0022] In one embodiment, the wound cell further includes a positive tab and a negative tab, the positive tab being disposed in the middle of the positive current collector and the negative tab being disposed in the middle of the negative current collector.
[0023] A lithium battery comprising the wound cell described in any of the above embodiments.
[0024] Compared with the prior art, this disclosure has at least the following advantages:
[0025] Because the adhesive layer is located between the empty foil area of the negative electrode head and the single-layer fabric area of the head, and in the arc area of the winding head of the core body; in the projection direction of the thickness of the core body, the first end of the adhesive layer is located between the inner end of the positive electrode coating and the arc area of the winding head of the core body, so that the added adhesive layer compensates for the thickness of the positive and negative electrode overhang areas of the core head, improves the flatness of the wound cell, and reduces the risk of performance failure of the wound cell. In addition, the adhesive layer has high flexibility, making it less prone to wrinkling or cracking during winding, thereby effectively improving the flatness of the wound cell. The wound cell disclosed herein does not require coating, which avoids material waste; at the same time, it does not require increasing the formation pressure, which can effectively prevent the problem of poor electrolyte wetting due to increased pressure affecting the electrical performance of the wound cell. Attached Figure Description
[0026] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this disclosure 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.
[0027] Figure 1This is a schematic diagram of the structure of a wound battery cell in one direction according to an embodiment of the present invention;
[0028] Figure 1a for Figure 1 The diagram shows a schematic of the negative electrode structure of a wound battery cell in one direction.
[0029] Figure 1b for Figure 1 A schematic diagram of the negative electrode sheet of the wound battery cell from another direction;
[0030] Figure 2 This is a schematic diagram of the structure of a wound battery cell in one direction according to another embodiment of the present invention;
[0031] Figure 2a for Figure 2 The diagram shows a schematic of the negative electrode structure of a wound battery cell in one direction.
[0032] Figure 2b for Figure 2 A schematic diagram of the negative electrode sheet of the wound battery cell from another direction;
[0033] Figure 3 This is a schematic diagram of the one-direction structure of a wound battery cell according to another embodiment of the present invention;
[0034] Figure 3a for Figure 3 The diagram shows a schematic of the positive electrode structure of a wound battery cell in one direction.
[0035] Figure 3b for Figure 3 A schematic diagram of the positive electrode sheet of the wound battery cell from another direction;
[0036] Figure 4 This is a schematic diagram of a traditional conventional wound battery cell in one direction.
[0037] Figure 5 A schematic diagram of one aspect of adding coating to a traditional negative electrode sheet.
[0038] Reference numerals: 10, wound cell; 100, positive electrode sheet; 110, positive electrode current collector; 120, first positive electrode coating layer; 130, second positive electrode coating layer; 140, empty foil area at the head of the positive electrode; 141, third arc area; 160, inner end; 200, negative electrode sheet; 210, negative electrode current collector; 220, first negative electrode coating layer; 230, second negative electrode coating layer; 240, empty foil area at the head of the negative electrode; 241, first arc area; 242, second arc area; 243, first horizontal section; 244, bent section; 245, second horizontal section; 250, single-layer fabric area at the head; 300, adhesive tape layer; 310, first straight section; 320, bent section; 330, second straight section; 500, positive electrode tab; 600, negative electrode tab; 700, separator. Detailed Implementation
[0039] To facilitate understanding of this disclosure, a more complete description will be given below with reference to the accompanying drawings, which illustrate preferred embodiments of the present disclosure. However, this disclosure can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure.
[0040] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.
[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0042] To better understand the technical solutions and beneficial effects of this disclosure, the following detailed description is provided in conjunction with specific embodiments:
[0043] like Figure 1 and Figure 2 As shown, a wound battery cell 10 in one embodiment includes a core body and an adhesive layer 300. The core body includes a positive electrode sheet 100, a negative electrode sheet 200, and a separator 700 wound together. The positive electrode sheet 100 includes a positive current collector 110 and a positive coating layer. The positive coating layers are respectively disposed on both sides of the positive current collector 110, namely a first positive coating layer 120 and a second positive coating layer 130. The first positive coating layer 120 is located on the outer side of the positive current collector 110 winding, and the second positive coating layer 130 is located on the inner side of the positive current collector 110 winding. The end of the positive coating layer at the starting end of the winding of the positive electrode sheet 100 is the inner end 160, that is, the starting end of the winding of the first positive coating layer 120 and the second positive coating layer 130 is the inner end 160.
[0044] The negative electrode sheet 200 includes a negative electrode current collector 210 and a negative electrode coating layer. The negative electrode coating layer is disposed on both sides of the negative electrode current collector 210, namely a first negative electrode coating layer 220 and a second negative electrode coating layer 230. The first negative electrode coating layer 220 is located on the outer side of the winding of the negative electrode current collector 210, and the second negative electrode coating layer 230 is located on the inner side of the winding of the negative electrode current collector 210. The negative electrode sheet 200 has a negative electrode head empty foil area 240 and a head single fabric area 250. The negative electrode head empty foil area 240 is located at the starting end of the winding of the negative electrode sheet 200, and the head single fabric area 250 is connected to the negative electrode head empty foil area 240. The negative electrode current collector 210 of the head single fabric area 250 is... The outer side of the winding is provided with the negative electrode coating layer, that is, the head single fabric area 250 is formed with the first negative electrode coating layer 220, so that the head single fabric area 250 and the negative electrode head empty foil area 240 form a step; the outer and inner sides of the winding of the negative electrode current collector 210 of the head single fabric area 250 are exposed to the negative electrode coating layer and form the negative electrode head empty foil area 240; that is, the inner side of the winding of the negative electrode current collector 210 is exposed to the second negative electrode coating layer 230 and forms the negative electrode head empty foil area 240; in the projection direction of the thickness of the core body, the negative electrode coating layer of the negative electrode sheet 200 covers and extends beyond the positive electrode coating of the positive electrode sheet 100; so as to realize the setting of the overhang area of the positive and negative electrodes at the core head.
[0045] In this embodiment, the inner side of the positive current collector 110 and the inner side of the negative current collector 210 are both arranged facing the diaphragm 700, while the outer side of the positive current collector 110 and the outer side of the negative current collector 210 are both arranged away from the diaphragm 700.
[0046] It is understood that since the adhesive tape layer 300 is located between the negative electrode head empty foil area 240 and the head single fabric area 250, and is situated in the arc area of the winding head of the core body; that is, the adhesive tape layer 300 is located in the arc area of the overhang region of the positive and negative electrodes at the core head, so that in the projection direction of the thickness of the core body, the first end of the adhesive tape layer 300 is located between the inner end 160 of the positive electrode coating and the arc area of the winding head of the core body, the added adhesive tape layer 300 compensates for the thickness of the overhang region of the positive and negative electrodes at the core head, improves the flatness of the wound cell 10, and reduces the risk of performance failure of the wound cell 10. In addition, the adhesive tape layer 300 has high flexibility, making it less prone to wrinkling or cracking during winding, thereby effectively improving the flatness of the wound cell 10. The wound cell 10 disclosed herein does not require coating, thus avoiding material waste; at the same time, it does not require increasing the formation pressure, which can effectively prevent the problem of poor electrolyte wetting due to increased pressure, thus affecting the electrical performance of the wound cell 10.
[0047] It can be understood that the position between the negative electrode head empty foil area 240 and the head single fabric area 250 can be on the outside of the negative electrode head empty foil area 240, on the inside of the head single fabric area 250, or on the diaphragm 700 or positive electrode head empty foil area 140 between the outside of the negative electrode head empty foil area 240 and the inside of the head single fabric area 250.
[0048] For example, in one embodiment, the adhesive tape layer 300 can be applied to the outer arcuate area of the negative electrode head empty foil area 240, that is, the arcuate area outside the negative electrode head empty foil area 240 at the winding head of the core body is the first arcuate area 241, and the adhesive tape layer 300 covers the first arcuate area 241, such as... Figure 1 , Figure 1a and Figure 1b As shown, the addition of the adhesive tape layer 300 can compensate for the thickness of the first arc area 241 of the winding head of the core body, thereby improving the flatness of the wound cell 10.
[0049] For example, in one embodiment, the adhesive tape layer 300 can be applied to the arc-shaped area of the negative electrode head empty foil area 240 inside the head single fabric area 250, that is, the arc-shaped area of the negative electrode head empty foil area 240 inside the negative electrode head single fabric area 250 of the winding head of the core body is the second arc-shaped area 242, so that the adhesive tape layer 300 covers the second arc-shaped area 242, such as... Figure 2 , Figure 2a and Figure 2b As shown, the addition of the adhesive tape layer 300 can compensate for the thickness of the second arc area 242 of the winding head of the core body, thereby improving the flatness of the wound core 10.
[0050] When the adhesive tape layer 300 covers the first arc area 241 or the second arc area 242, such as Figure 1 As shown, in the vertical direction A of the projection of the thickness of the core body, the first end of the adhesive layer 300 is flush with the inner end 160, and the second end of the adhesive layer 300 abuts against the negative electrode coating layer, so as to achieve full coverage of the adhesive layer 300 in the first arc area 241 and the second arc area 242.
[0051] In one embodiment, the first arc region 241 includes a first horizontal portion 243, a bent portion 244, and a second horizontal portion 245 connected in sequence. The starting end of the first horizontal portion 243 abuts against the negative electrode coating layer. In the vertical projection direction of the thickness of the core body, the ending end of the second horizontal portion 245 is flush with the inner end portion 160. Since the adhesive tape layer 300 includes a first straight section 310, a bent section 320, and a second straight section 330 connected in sequence, the first straight section 310 covers the first horizontal portion 243, the bent section 320 covers the bent portion 244, and the second straight section 330 covers the second horizontal portion 245, so that the adhesive tape layer 300 fully covers the first arc region 241, thereby achieving full coverage of the first arc region 241.
[0052] In one embodiment, the length of the first horizontal portion 243 accounts for (0.2-1.0) of the total length of the first arc region 241. Specifically, the length of the first horizontal portion 243 is 0.2mm-1.0mm.
[0053] Similarly, the second arc region 242 has a similar structure to the first arc region 241.
[0054] For example, in some other embodiments, the adhesive tape layer 300 may also be disposed on the arcuate area of the diaphragm 700 located between the outer side of the head empty foil area and the inner side of the head single fabric area 250.
[0055] For example, in some other embodiments, the adhesive tape layer 300 may also be disposed in the empty foil area 140 at the positive electrode head.
[0056] For example, such as Figure 3 , Figure 3a and Figure 3b As shown, in one embodiment, the positive electrode sheet 100 further forms a positive electrode head empty foil region 140, the positive electrode current collector 110 of the positive electrode head empty foil region 140 is connected and exposed at the inner end 160, the outer arc region of the positive electrode current collector 110 of the positive electrode head empty foil region 140 is a third arc region 141, the outer side of the third arc region 141 of the positive electrode head empty foil region 140 is on the same side as the first positive electrode coating layer 120; the adhesive tape layer 300 covers the third arc region 141, so that the adhesive tape... Layer 300 covers the third arc region 141; or, in one embodiment, the arc region on the inner side of the positive current collector 110 of the positive electrode head empty foil region 140 is the fourth arc region, and the fourth arc region on the inner side of the positive electrode head empty foil region 140 is on the same side as the second positive electrode coating layer 130; the adhesive layer 300 covers the fourth arc region, so that the addition of the adhesive layer 300 can compensate for the thickness of the third arc region 141 or the fourth arc region of the winding head of the core body, and improve the flatness of the wound cell 10.
[0057] When the adhesive tape layer 300 covers the third arc area 141 on the outside of the positive electrode head empty foil area 140 or the fourth arc area on the inside of the negative electrode head empty foil area 240, in the vertical direction of the projection of the thickness of the core body, the first end of the adhesive tape layer 300 is flush with the inner end 160, and the second end of the adhesive tape layer 300 abuts against the positive electrode coating layer, so as to achieve full coverage of the adhesive tape layer 300 in the third arc area 141 and the fourth arc area, thereby effectively improving the flatness of the wound cell 10.
[0058] In one embodiment, the third arc region 141 includes a first horizontal portion 243, a bent portion 244, and a second horizontal portion 245 connected in sequence. The starting end of the first horizontal portion 243 abuts against the negative electrode coating layer. In the vertical projection direction of the thickness of the core body, the ending end of the second horizontal portion 245 is flush with the inner end portion 160. The adhesive tape layer 300 includes a first straight section 310, a bent section 320, and a second straight section 330 connected in sequence. The first straight section 310 covers the first horizontal portion 243, the bent section 320 covers the bent portion 244, and the second straight section 330 covers the second horizontal portion 245, so as to achieve full coverage of the third arc region 141 by the adhesive tape layer 300.
[0059] Similarly, the fourth arc region has a similar structure to the third arc region 141, achieving full coverage of the fourth arc region by the adhesive paper layer 300.
[0060] It is understandable that if the thickness of the adhesive tape layer 300 exceeds the thickness of the positive or negative electrode coating layer, the adhesive tape layer 300 will be too thick to adequately compensate for the thickness of the positive and negative electrode overhang areas at the core head, thus failing to improve the flatness of the wound cell 10. Therefore, in one embodiment, the thickness of the adhesive tape layer 300 does not exceed the thickness of the positive or negative electrode coating layer, ensuring that the adhesive tape layer 300 is not too thick and thus does not fail to improve the flatness of the wound cell 10.
[0061] It is understandable that if the thickness of the adhesive tape layer 300 is too low, it will also fail to improve the flatness of the wound battery cell 10. Therefore, in one embodiment, such as Figure 1a , Figure 2a and Figure 3aAs shown, the thickness of the adhesive tape layer 300 accounts for 60% to 100% of the thickness of the positive electrode coating layer or the negative electrode coating layer, so as to ensure that the thickness of the adhesive tape layer 300 is suitable, thereby ensuring that the adhesive tape layer 300 after winding can better reduce the thickness compensation of the positive and negative electrode overhang area at the head of the core, thereby improving the flatness of the wound cell 10.
[0062] In one embodiment, the thickness of the adhesive tape layer 300 is 10μm to 50μm, and the adhesive width is 3mm to 20mm.
[0063] In one embodiment, the adhesive tape layer 300 includes a base layer and an adhesive layer connected together. In one embodiment, the base layer includes any one of a PET layer, a PP layer, a PI layer, and a rubber layer to ensure that the base layer of the adhesive tape layer 300 has high flexibility, thereby ensuring that the adhesive tape layer 300 is not prone to wrinkling or cracking during winding, which helps to improve the flatness of the wound battery cell 10.
[0064] In one embodiment, the thickness of the adhesive layer accounts for 60% to 80% of the thickness of the adhesive tape layer 300, to ensure that the adhesive layer has high adhesion, thereby ensuring that the adhesive tape layer 300 is not prone to peeling off during long-term use. Since the material of the adhesive layer is a known material, the material of the adhesive layer will not be further described in this disclosure.
[0065] like Figure 1 , Figure 1b and Figure 3b As shown, in one embodiment, the wound cell 10 further includes a positive tab 500 and a negative tab 600. The positive tab 500 is disposed in the middle of the positive current collector 110, and the negative tab 600 is disposed in the middle of the negative current collector 210, so as to ensure that the prepared wound cell 10 is a wound cell 10 with the tabs in the middle. This allows the wound cell 10 with the tabs in the middle to better reduce internal resistance, significantly reduce heat generation, and improve fast charging and fast discharging capabilities; it also helps to extend cycle life.
[0066] This disclosure also provides a lithium battery, including the wound cell 10 described in any of the above embodiments. The lithium battery further includes a housing, in which the wound cell 10 is disposed.
[0067] Compared with the prior art, this disclosure has at least the following advantages:
[0068] Because the adhesive tape layer 300 is located between the negative electrode head empty foil area 240 and the head single fabric area 250, and is situated in the arc area of the winding head of the core body; in the projection direction of the thickness of the core body, the first end of the adhesive tape layer 300 is located between the inner end 160 of the positive electrode coating and the arc area of the winding head of the core body, the added adhesive tape layer 300 compensates for the thickness of the positive and negative electrode overhang areas of the core head, improving the flatness of the wound cell 10 and reducing the risk of performance failure of the wound cell 10. Furthermore, the adhesive tape layer 300 has high flexibility, making it less prone to wrinkling or cracking during winding, thereby effectively improving the flatness of the wound cell 10. The wound cell 10 of this disclosure does not require coating, avoiding material waste; at the same time, it does not require increased formation pressure, effectively preventing problems such as poor electrolyte wetting due to increased pressure affecting the electrical performance of the wound cell 10.
[0069] The following are some specific embodiments. It should be noted that the following embodiments do not exhaust all possible situations, and the materials used in the following embodiments are commercially available unless otherwise specified.
[0070] Example 1
[0071] use Figure 1 The position of the adhesive tape layer is shown in the design to prepare the wound battery cell.
[0072] Example 2
[0073] use Figure 2 The position of the adhesive tape layer is shown in the design to prepare the wound battery cell.
[0074] Example 3
[0075] use Figure 3 The position of the adhesive tape layer is shown in the design to prepare the wound battery cell.
[0076] Comparative Example 1
[0077] use Figure 4 The image shows a wound battery cell fabricated without an adhesive paper layer.
[0078] Comparative Example 2
[0079] use Figure 5 The traditional method of adding coating to the A or B side of the negative electrode is shown to prepare wound cells.
[0080] The wound cells prepared in Examples 1-3 and Comparative Examples 1-2 were used to fabricate lithium batteries for performance comparison, and the experimental data in the table below were obtained:
[0081] Cyclic performance test method: The lithium battery is charged at 3C constant current and constant voltage to 4.5V, cut off at 0.05C, and discharged at 0.5C. After 1000 cycles, the lithium battery is disassembled to check the lithium deposition in the arc area of the positive and negative electrode plates, and is divided into no lithium deposition, slight lithium deposition, moderate lithium deposition and severe lithium deposition.
[0082] Example 1 1000 No lithium precipitation Example 2 1000 No lithium precipitation Example 3 1000 No lithium precipitation Comparative Example 1 700 Severe lithium precipitation Comparative Example 2 1000 Light lithium precipitation
[0083] As can be seen from the table above, when the adhesive layer is placed in the first, second, or third arc area in Examples 1 to 3, it not only effectively improves the flatness of the wound battery cell, but also reduces the risk of performance failure of the wound battery cell, making the overall performance of Examples 1 to 3 significantly better than that of Comparative Examples 1 to 2.
[0084] The embodiments described above are merely illustrative of several implementations of this disclosure, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the disclosed patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this disclosure, and these all fall within the protection scope of this disclosure. Therefore, the protection scope of this patent should be determined by the appended claims.
Claims
1. A wound battery cell, characterized in that, include: The core body includes a positive electrode sheet (100), a negative electrode sheet (200), and a separator (700) wound together. The positive electrode sheet (100) includes a positive electrode current collector (110) and a positive electrode coating layer. The positive electrode coating layer is respectively disposed on both sides of the positive electrode current collector (110), and the end of the positive electrode coating layer located at the winding start end of the positive electrode sheet (100) is the inner end (160). The negative electrode sheet (200) includes a negative electrode current collector (210) and a negative electrode coating layer, the negative electrode coating layer being disposed on both sides of the negative electrode current collector (210); the negative electrode sheet (200) has a negative electrode head empty foil area (240) and a head single fabric area (250); the negative electrode head empty foil area (240) is located at the winding start end of the negative electrode sheet (200); the head single fabric area (250) is connected to the negative electrode head empty foil area (240), the negative electrode coating layer is disposed on the outer side of the winding of the negative electrode current collector (210) in the head single fabric area (250), and the inner side of the winding of the negative electrode current collector (210) in the head single fabric area (250) is exposed to the negative electrode coating layer; in the projection direction of the thickness of the core body, the negative electrode coating layer of the negative electrode sheet (200) covers and extends beyond the positive electrode coating of the positive electrode sheet (100); An adhesive tape layer (300) is disposed between the negative electrode head empty foil area (240) and the head single fabric area (250), and is located in the arc area of the winding head of the core body; in the projection direction of the thickness of the core body, the first end of the adhesive tape layer (300) is located between the inner end (160) of the positive electrode coating and the arc area of the winding head of the core body.
2. The wound battery cell according to claim 1, characterized in that, The outer arc area of the negative electrode head empty foil area (240) is the first arc area (241), and the inner arc area of the head single fabric area (250) is the second arc area (242). The adhesive paper layer (300) covers the first arc area (241) or the second arc area (242).
3. The wound battery cell according to claim 2, characterized in that, In the direction perpendicular to the projection of the thickness of the core body, the first end of the adhesive layer (300) is flush with the inner end (160); The second end of the adhesive tape layer (300) abuts against the negative electrode coating layer.
4. The wound battery cell according to claim 3, characterized in that, The first arc region (241) or the second arc region (242) includes a first horizontal part (243), a bent part (244), and a second horizontal part (245) connected in sequence. The starting end of the first horizontal part (243) abuts against the negative electrode coating layer. In the vertical projection direction of the thickness of the core body, the ending end of the second horizontal part is flush with the inner end (160). The adhesive tape layer (300) includes a first straight section (310), a curved section (320), and a second straight section (330) connected in sequence. The first straight section (310) covers the first horizontal portion (243), the curved section (320) covers the bent portion (244), and the second straight section (330) covers the second horizontal portion (245).
5. The wound battery cell according to claim 1, characterized in that, The positive electrode sheet (100) also forms a positive electrode head empty foil area (140), the positive electrode current collector (110) of the positive electrode head empty foil area (140) is connected and exposed at the inner end (160), the outer arc area of the positive electrode current collector (110) of the positive electrode head empty foil area (140) is the third arc area (141), the inner arc area of the positive electrode current collector (110) of the positive electrode head empty foil area (140) is the fourth arc area, and the adhesive paper layer (300) covers the third arc area (141) or the fourth arc area.
6. The wound battery cell according to claim 5, characterized in that, In the direction perpendicular to the projection of the thickness of the core body, the first end of the adhesive layer (300) is flush with the inner end (160); The second end of the adhesive tape layer (300) abuts against the positive electrode coating layer.
7. The wound battery cell according to claim 1, characterized in that, The thickness of the adhesive paper layer (300) accounts for 60% to 100% of the thickness of the positive electrode coating layer or the negative electrode coating layer.
8. The wound battery cell according to claim 1, characterized in that, The adhesive tape layer (300) includes a connected base layer and an adhesive layer; and / or, The thickness of the adhesive layer accounts for 60% to 80% of the thickness of the adhesive paper layer (300).
9. The wound battery cell according to claim 1, characterized in that, The wound battery cell also includes a positive electrode tab (500) and a negative electrode tab (600), the positive electrode tab (500) being disposed in the middle of the positive current collector (110), and the negative electrode tab (600) being disposed in the middle of the negative current collector (210).
10. A lithium battery, characterized in that, Includes the wound battery cell according to any one of claims 1-9.