Pole piece, battery cell structure and battery

Abstract

The application relates to a pole piece, a battery cell structure and a battery. The pole piece comprises a current collector, an active material layer and a protection groove position arranged along the edge of the pole piece; the protection groove position comprises a through groove and an annular groove; the annular groove is recessed inward from an end of the active material layer away from the current collector, and the inner bottom surface of the annular groove and the end surface of the active material layer close to the current collector are provided with a spacing of the groove bottom thickness; the through groove penetrates the active material layer via the inner bottom surface of the annular groove, and a spacing is provided between the groove opening edge of the through groove and the outer edge of the annular groove on the same side. The pole piece is designed with the through groove penetrating the active material layer and the closed annular groove surrounding the outer periphery of the through groove, so that the protection adhesive paper is stably embedded in the annular groove and stably bonded with the current collector with large adhesive force. On the premise of not increasing the thickness of the pole piece, the adhesive paper embedding technology can realize stable bonding while avoiding the exposure of the metal current collector, and the safety and reliability of the battery cell are enhanced.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to an electrode, cell structure, and battery. Background Technology

[0002] During the winding and forming process of lithium-ion battery cells, structural defects such as metal burrs and sharp edges are easily generated at the electrode tabs after the electrode sheets are slit and die-cut. This is a process problem that is difficult to completely avoid in the industry. After winding, the burrs at the electrode tabs are sharp and have high hardness. In the compact assembly space inside the cell, they can easily pierce the separator separating the positive and negative electrode sheets, causing the active materials of the positive and negative electrode sheets with opposite polarities to come into direct contact. This can lead to conductivity between the positive and negative electrodes inside the lithium battery, causing a short circuit in the cell. This can not only directly lead to the scrapping of the battery, but may also cause safety hazards such as thermal runaway, fire, or even explosion, seriously affecting the production yield and safety of lithium batteries. To address the short circuit issue caused by tab burrs in the battery cell, the current industry-standard solution involves applying protective adhesive tape to the corresponding position of the opposite polarity electrode. The tape's insulating and barrier properties cover the corresponding area of ​​the electrode, preventing direct contact between the tab burrs and the active material of the opposite electrode. This avoids the risk of separator puncture and internal short circuits, thus protecting the internal structure of the battery cell. Currently, the placement and positioning of the protective tape primarily relies on pre-set rectangular grooves on the electrode. The tape's adhesive properties are used to adhere and fix it to the bottom surface of the rectangular groove, completing the tape's positioning and installation.

[0003] However, existing adhesive tape mounting slots for positive and negative electrodes are mostly simple rectangular grooves with no auxiliary limiting or reinforcing structures. The protective tape relies entirely on its own adhesiveness for adhesion and fixation, resulting in extremely poor bonding stability. In subsequent continuous processes such as lithium battery sheet fabrication and winding, the electrode surface needs to be thoroughly cleaned with a brush to remove residual dust, debris, and other impurities to ensure the precision of cell forming. During the brushing process, the surface of the protective tape in the slot is continuously rubbed and scraped. The continuous mechanical scraping force can easily overcome the adhesive tape's own adhesion, causing the protective tape to curl, shift, or even fall off completely. The detached protective tape directly exposes the protective area of ​​the electrode, completely losing its insulating barrier effect. This not only significantly reduces the yield rate of lithium battery production processes and increases production costs, but also exposes the cell to the risk of short circuits caused by tab burrs piercing the separator and direct conduction between the positive and negative electrodes. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to provide an electrode sheet by designing a through groove that penetrates the active material layer and a closed annular groove that protrudes from the through groove and surrounds the outer periphery of the through groove, so as to achieve stable embedding of protective adhesive paper in the annular groove and stable adhesion with the current collector with high adhesion force. Without increasing the thickness of the electrode sheet, this adhesive paper embedding technology can achieve stable adhesion while avoiding exposure of the metal current collector, thereby enhancing the safety and reliability of the battery cell.

[0005] Another objective of this invention is to provide a cell structure and battery that, by differentiating the protection slots of the positive and negative electrode plates, reduces the loss of active lithium in the positive electrode plate and increases the energy density of the cell, while ensuring process yield and cell safety and reliability. At the same time, it prevents lithium ions from accumulating in the protection slots of the negative electrode plate to form lithium dendrites, thus preventing cell safety failure.

[0006] This invention provides an electrode sheet, comprising: current collector; An active material layer covering the surface of the current collector; A protective groove for accommodating protective adhesive paper is provided along the edge of the electrode sheet; the protective groove includes a through groove and an annular groove; the annular groove is recessed inward through the end face of the active material layer away from the current collector, and the inner bottom surface of the annular groove and the end face of the active material layer near the current collector are spaced apart by the groove bottom thickness; the through groove penetrates the active material layer through the inner bottom surface of the annular groove, and there is a gap between the groove opening edge of the through groove and the outer edge of the annular groove on the same side.

[0007] Furthermore, the cutting dimension of the annular groove along the length of the electrode sheet is greater than the width of the protective adhesive paper; the groove depth of the annular groove is greater than the thickness of the protective adhesive paper.

[0008] Furthermore, the bottom thickness of the annular groove is 5~15μm; Furthermore, along the width direction of the electrode, the distance between the first edge of the electrode near the protective groove and the groove edge of the through groove on the same side is 4~5mm; the distance between the groove edge of the through groove away from the first edge and the outer edge of the annular groove on the same side is 2.5~3.5mm. Along the length of the electrode sheet, the distance between the edge of the groove opening and the outer edge of the annular groove on the same side is 2.5~3.5mm.

[0009] The present invention also provides a cell structure, comprising: A positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; The positive electrode and / or the negative electrode include the electrodes described above.

[0010] Furthermore, the positive electrode sheet includes a first current collector, a positive electrode active material layer covering both ends of the first current collector, and a first protective groove; the first protective groove includes a first through groove that completely penetrates the positive electrode active material layer and a first annular groove cut from the positive electrode active material layer away from the first current collector towards the first current collector, the bottom of the first annular groove completely covering the outer periphery of the first through groove.

[0011] Furthermore, a base coating is provided between the first current collector and the positive electrode active material layer; the through groove and the orthographic projection of the base coating on the end face of the first current collector at least partially overlap.

[0012] Furthermore, the negative electrode sheet includes a second current collector, a negative electrode active material layer covering both ends of the second current collector, and a second protective groove; the second protective groove includes a second through groove that completely penetrates the negative electrode active material layer and a second annular groove cut from one end of the negative electrode active material layer away from the second current collector toward the second current collector, the bottom of the second annular groove at least partially covering the outer periphery of the second through groove.

[0013] Furthermore, the bottom surface of the second annular groove is provided with an adhesive tape pasting area in the middle and an edge area outside the adhesive tape pasting area. The edge area accommodates no more than three foil-diffusing points, and the foil-diffusing area of ​​each foil-diffusing point is ≤0.5mm². 2 .

[0014] The present invention also provides a battery, comprising: the cell structure described in the present invention.

[0015] The beneficial effects of this invention are as follows: (1) By embedding the protective adhesive paper in the protective groove, the protective adhesive paper can be effectively prevented from protruding from the surface of the active material layer without increasing the thickness of the electrode, thus avoiding the protective adhesive paper from curling, shifting or even falling off completely. (2) By designing a through groove that penetrates the active material layer and a closed annular groove that protrudes from the through groove and surrounds the outer periphery of the through groove, the protective adhesive paper is stably embedded in the annular groove and is stably bonded with the current collector with a large adhesive force. While achieving stable bonding, the metal current collector can be avoided from being exposed, thus enhancing the safety and reliability of the battery cell. (3) Differentiate the design and quality control of the protective glue groove size on the positive and negative electrode sheets, reduce the loss of active lithium on the positive electrode sheet and improve the energy density of the battery cell under the premise of ensuring the process yield and the safety and reliability of the battery cell, and at the same time prevent lithium ions from accumulating in the protective groove of the negative electrode sheet to form lithium dendrites, which would cause the battery cell to fail. (4) To address the differences in the active materials and current collectors of the positive and negative electrode sheets, the protective glue tanks of the positive and negative electrode sheets are cleaned differently to improve the processing accuracy and batch production consistency during the cleaning process of the protective glue tanks, and at the same time improve the quality reliability of the protective glue tanks.

[0016] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0017] Figure 1 A schematic diagram of the structure of an electrode provided in this application embodiment. Figure 1 ; Figure 2 A schematic diagram of the structure of an electrode provided in this application embodiment. Figure 2 ; Figure 3 for Figure 2 A magnified view of a portion of the image; Figure 4 A schematic diagram illustrating the application of protective tape to the protective slot provided in an embodiment of this application; Figure 5 for Figure 2 A schematic diagram of the AA cross-section; Figure 6 for Figure 2 BB cross-sectional diagram; Figure 7 for Figure 6 A magnified view of a portion of the image; Figure 8 This is a schematic diagram of another embodiment of the protective slot provided in this application. Figure 9 This is a schematic diagram of a battery cell structure provided in an embodiment of this application; Figure 10 This is a schematic diagram of the structure of the positive electrode sheet provided in the embodiments of this application; Figure 11 This is a schematic diagram of the negative electrode sheet provided in an embodiment of this application.

[0018] In the diagram: 10-Electrode; 11-Current collector; 12-Active material layer; 13-Protective groove; 131-Through groove; 132-Annular groove; 14-Taper groove; 20-Protective adhesive tape; 30-Positive electrode; 31-First current collector; 32-Positive active material layer; 33-First protective groove; 331-First through groove; 332-First annular groove; 34-Bottom coating; 40-Negative electrode; 41-Second current collector; 42-Negative active material layer; 43-Second protective groove; 431-Second through groove; 432-Second annular groove; 4321-Adhesive tape pasting area; 4322-Edge area; 50-Separator. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In the description of this invention, it should be noted that the terms "vertical direction," "up," "down," and "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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 the invention. Furthermore, "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or a 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 invention according to the specific circumstances.

[0022] To address the short circuit issue caused by tab burrs in the battery cell, the current industry-standard solution involves applying protective adhesive tape to the corresponding position of the opposite polarity electrode. The tape's insulating and barrier properties cover the corresponding area of ​​the electrode, preventing direct contact between the tab burrs and the active material of the opposite electrode. This avoids the risk of separator puncture and internal short circuits, thus protecting the internal structure of the battery cell. Currently, the placement and positioning of the protective tape primarily relies on pre-set rectangular grooves on the electrode. The tape's adhesive properties are used to adhere and fix it to the bottom surface of the rectangular groove, completing the tape's positioning and installation.

[0023] However, existing adhesive tape mounting slots for positive and negative electrodes are mostly simple rectangular grooves with no auxiliary limiting or reinforcing structures. The protective tape relies entirely on its own adhesiveness for adhesion and fixation, resulting in extremely poor bonding stability. Therefore, in subsequent continuous processes such as lithium battery sheet fabrication and winding, the electrode surface needs to be thoroughly cleaned with a brush to remove residual dust, debris, and other impurities to ensure cell forming accuracy. During the brushing process, the continuous friction and scraping of the protective tape surface within the slot can easily overcome the tape's own adhesive strength, leading to edge lifting, displacement, or even complete detachment. Detached protective tape directly exposes the electrode's protective area, completely losing its insulating barrier effect. This not only significantly reduces the yield rate of lithium battery production processes and increases production costs, but also exposes the cell to the risk of short circuits caused by tab burrs piercing the separator and direct conduction between the positive and negative electrodes.

[0024] Based on this, please refer to Figure 1-8 This application provides an electrode sheet, including a current collector 11, an active material layer 12 covering the surface of the current collector 11, and a protective groove 13 disposed along the edge of the electrode sheet 10 for accommodating protective adhesive paper 20. The protective groove 13 includes a through groove 131 and a closed annular groove 132; the through groove 131 penetrates the active material layer 12; the annular groove 132 is recessed inward through the end of the active material layer 12 away from the current collector 11, and the inner bottom surface of the annular groove 132 and the end surface of the active material layer 12 near the current collector 11 are provided with a certain distance defined as the groove bottom thickness, and a certain distance is provided between the groove opening edge of the through groove 131 and the outer edge of the annular groove 132 on the same side. This application embodiment designs a through groove 131 that penetrates the active material layer 12 and a closed annular groove 132 that protrudes from the through groove 131 and surrounds the outer periphery of the through groove 131. This achieves stable embedding of the protective adhesive paper 20 within the annular groove 132 and strong adhesion between it and the current collector 11. Without increasing the thickness of the electrode 10, it achieves stable adhesion while preventing the metal current collector 11 from being exposed, thus enhancing the safety and reliability of the battery cell.

[0025] Understandably, the electrode 10 also has tab grooves 14 for mounting tabs, and protective slots 13 are located on the active material layers 12 on both the upper and lower surfaces of the electrode 10. The protective slots 13 on both sides are staggered according to the designed positioning distance, and their positions are determined based on the specific positions of the tab grooves 14 of adjacent electrode 10 to ensure that the positive and negative tabs are accurately aligned and the protective adhesive paper 20 is correctly matched after winding. Details will not be elaborated here.

[0026] Furthermore, in some embodiments, the cutting dimension W1 of the annular groove 132 along the length direction of the electrode 10 is greater than the width W2 of the adhesive paper, and the cutting dimension L1 of the annular groove 132 along the width direction of the electrode 10 is greater than the embedding length L2 of the protective adhesive paper 20, that is, the length of the adhesive paper from the edge of the electrode 10 to one end away from the edge of the electrode 10. This is so that the protective adhesive paper 20 can be embedded in the annular groove 132, and its two ends in width will not protrude from the annular groove 132, which would cause the protective adhesive paper 20 to curl up. This avoids the ends of the protective adhesive paper 20 protruding and covering the active material layer 12 outside the annular groove 132, which would increase the thickness of the battery cell and cause it to fall off during subsequent brushing operations.

[0027] Preferably, the cutting dimension W1 of the annular groove 132 along the length direction of the electrode 10 and the width W2 of the adhesive paper satisfy the following condition: 1.5mm ≤ W1 - W2 ≤ 2.5mm. The cutting dimension L1 of the annular groove 132 along the width direction of the electrode 10 and the embedding length L2 of the protective adhesive paper 20 satisfy the following condition: 1mm ≤ L1 - L2 ≤ 2mm.

[0028] Furthermore, in some embodiments, the depth of the annular groove 132 is less than the thickness of the active material layer 12 and greater than or equal to the thickness of the protective adhesive paper 20. This ensures that the protective adhesive paper 20 does not protrude from the upper surface of the active material layer 12, thereby reducing the overall thickness of the subsequent battery cell and preventing the protective adhesive paper 20 from being detached from the annular groove 132 due to frequent friction during subsequent brushing operations.

[0029] Please see 6 and Figure 7 Preferably, during the actual cleaning and molding process of the annular groove 132, the bottom thickness H1 of the annular groove 132 is 5~15μm. Within this thickness range, the bottom of the annular groove 132 can ensure a uniform thickness of active material during cleaning. However, when H1 < 5μm, it is easy to cause point-like leakage during cleaning, which can easily lead to short circuits and pose a high safety risk. When H1 > 15μm, the insufficient depth of the annular groove 132 may cause the protective adhesive paper 20 to protrude from the upper surface of the active material layer 12, which will increase the thickness of the electrode 10 after the protective adhesive paper 20 is bonded.

[0030] Please see Figure 2-4Furthermore, along the width direction of the electrode 10, the edge of the electrode 10 closest to the protective groove 13 is defined as the first edge. The distance 'a' between this first edge and the groove edge 'a' of the same-side through groove 131 is 4-5 mm. The distance 'b' between the groove edge 'b' of the through groove 131 furthest from the first edge and the outer edge of the same-side annular groove 132 is 2.5-3.5 mm. Along the length direction of the electrode 10, the distance 'c' between the edge of the through groove 131 and the outer edge of the same-side annular groove 132 is 2.5-3.5 mm. Combined with the dimensions of the annular groove 132, the protective adhesive paper 20 has sufficient space to evenly adhere to the bottom of the annular groove 132, overcoming the problem of missing foil in the middle due to adhesion deviation during the application of the protective adhesive paper 20, thus avoiding potential short circuits and other defects.

[0031] In a preferred embodiment, the through groove 131 is centrally located at the bottom of the annular groove 132 so that the current collector 11 is stably bonded to the middle of the protective adhesive paper 20, and the annular groove 132 located outside the through groove 131 is uniformly bonded and fixed to the outer periphery of the protective adhesive paper 20 so as to improve the adhesion stability of the edge of the protective adhesive paper 20.

[0032] Please see Figure 7 In a preferred embodiment, both the through groove 131 and the annular groove 132 are rectangular in shape to fit the conventional square protective adhesive paper 20. It is understood that the cross-section of the through groove 131 can also be circular, trapezoidal, triangular, or other shapes, and the annular groove 132 is a regular or irregular shape that is closed around the periphery of the through groove 131 along the edge of the electrode 10, and is not limited thereto.

[0033] Please see Figure 8 Furthermore, as another preferred embodiment, the through groove 131 is inverted cone shape from the outside to the inside, that is, the inner wall of the through groove 131 is inclined. In this arrangement, it is convenient for the protective adhesive paper 20 to transition stably from the collector 11 at the bottom of the through groove 131 to the bottom of the outer annular groove 132, and the adhesion is more stable.

[0034] Please see Figure 9-11 This application also provides a battery cell structure, including: a positive electrode 30, a negative electrode 40, and a separator 50 disposed between the positive electrode 30 and the negative electrode 40; the positive electrode 30 and / or the negative electrode 40 include the electrodes described above.

[0035] Furthermore, the cell structure also includes protective adhesive paper 20 for bonding the protective slots of the positive electrode 30 and / or the negative electrode 40. Preferably, the protective adhesive paper 20 is a high-tack rubber adhesive paper with a peel strength of 5~10N / 25mm and an applicable temperature range of -20℃ to 85℃, which will not be described in detail here.

[0036] Please see Figure 9 and Figure 10Specifically, the positive electrode 30 includes a first current collector 31, a positive electrode active material layer 32 covering both ends of the first current collector 31, and a first protective groove 33. The first protective groove 33 includes a first through groove 331 that completely penetrates the positive electrode active material layer 32 and a first annular groove 332 cut from the end face of the positive electrode active material layer 32 away from the first current collector 31 toward the first current collector 31. The bottom of the first annular groove 332 has a groove bottom thickness and completely covers the outer periphery of the first through groove 331. In this configuration, protective adhesive paper 20 is embedded in the first annular groove 332, with the middle part of the protective adhesive paper 20 bonded to the first current collector 31 at the bottom of the first through groove 331, and its edge bonded to the bottom of the first annular groove 332.

[0037] Furthermore, in some embodiments, a base coating 34 is also provided between the first current collector 31 and the positive electrode active material layer 32. In this configuration, the orthogonal projection of the channel on the surface of the first current collector 31 covers at least part of the base coating 34. That is, for the first current collector 31 with the base coating 34, during the cleaning process to form the first channel 331, it is necessary to completely or partially retain the base coating 34 below the first channel 331 in order to pass the needle penetration test.

[0038] Please see Figure 9 and Figure 11 Specifically, the negative electrode sheet 40 includes a second current collector 41, a negative electrode active material layer 42 covering both ends of the second current collector 41, and a second protective groove 43. The second protective groove 43 includes a second through groove 431 that completely penetrates the negative electrode active material layer 42 and a second annular groove 432 cut from one end of the negative electrode active material layer 42 away from the second current collector 41 toward the second current collector 41. The bottom of the second annular groove 432 has a groove bottom thickness and at least partially covers the outer periphery of the second through groove 431. In this configuration, the protective adhesive paper 20 is embedded in the second annular groove 432, with the middle part of the protective adhesive paper 20 bonded to the second current collector 41 at the bottom of the second through groove 431, and its edge bonded to the bottom of the second annular groove 432.

[0039] In some embodiments, the bottom surface of the second annular groove 432 is provided with an adhesive tape pasting area 4321 in the middle and an edge area 4322 on the outer periphery. In the actual production process, to control the negative electrode sheet 40, the edge area 4322 can be allowed to have foil leakage points. Specific control indicators are: the number of foil leakage points ≤ 3, and the leakage area of ​​the foil leakage points ≤ 0.5 mm. 2 .

[0040] Please see Figure 1-11 Based on the cell structure provided in the embodiments of this application, the embodiments of this application also provide a cleaning method for the first protective slot of the positive electrode, specifically including the following steps: S11, Determine the location and size to be cleaned on the surface of the positive electrode; S12, the positive electrode active material layer is subjected to initial laser cleaning treatment on the position to be cleaned according to the first cleaning conditions to form the first annular groove. S13, The positive electrode active material layer is subjected to laser cleaning again according to the second cleaning conditions to form the first through groove; S14, according to the third cleaning conditions, the edge of the tank is finely trimmed to form the first protective tank.

[0041] In the above steps, due to the high density of the positive electrode active material layer, the dense coating is gradually and effectively peeled off through three stages of power gradient. Specifically, the first, second, and third cleaning conditions all include parameters such as power, speed, and frequency.

[0042] As an example, the first annular groove and the first through groove are defined as rectangles. First, the position to be cleaned is determined, and according to the cell design specifications, the width W2 of the protective tape is determined to be 8mm, the embedding length L2 of the protective tape is 8mm, and the thickness of the positive electrode active material layer is 35μm. The dimensions of the first annular groove are determined to be: W1*L1*H1=10mm*9.5mm*25μm. The relative dimensions of the first through groove and the first annular groove are: the distance a from the edge of the first through groove to the edge of the positive electrode is 4.5mm, the distance b from the edge of the first through groove to the side of the first annular groove away from the edge of the electrode is 3mm, the distance c from the edge of the through groove to the outer edge of the annular groove on the same side is 3mm, and the dimensions of the first through groove are W3*L3=4mm*2mm.

[0043] Next, the first cleaning conditions were set as follows: power 68±5%, speed 16000mm / s, frequency 190kHz, for coarse cleaning to remove most of the active substances; the second cleaning conditions were set as follows: power 27±5%, speed 17000mm / s, frequency 800kHz, for further fine cleaning; the third cleaning conditions were set as follows: power 25±5%, speed 16000mm / s, frequency 1080kHz, for finishing the edges of the tank.

[0044] After cleaning, the thinning depth of the groove is measured with a micrometer to confirm that the thickness of the residual active material layer at the bottom of the first annular groove is within the range of 5~15μm; the appearance is inspected with a microscope to confirm that there is no foil leakage, and it is deemed qualified. Then, the protective tape is applied.

[0045] This application embodiment also provides a cleaning method for the second protective groove of the negative electrode, specifically including the following steps: S21, Determine the location and size to be cleaned on the surface of the negative electrode; S22, the negative electrode active material layer is subjected to initial laser cleaning treatment on the area to be cleaned according to the first cleaning conditions to form the second annular groove. S23, the negative electrode active material layer is subjected to laser cleaning again according to the second cleaning conditions to complete the cleaning of the second through tank and form the second protective tank.

[0046] In the above steps, since the negative electrode active material layer has a high laser absorption rate, by changing the power in two stages, and each cleaning condition includes displacement speed, engraving speed, power and frequency, the interaction time between the laser and the coating can be greatly shortened by using an extremely high scanning speed. While removing the graphite coating, the heat effect on the copper foil substrate is minimized, avoiding overheating or perforation.

[0047] As an example, the second annular groove and the second through groove are defined as rectangles. First, the position to be cleaned is determined, and according to the cell design specifications, in this embodiment, the second protective groove has the same dimensions as the first protective groove. Based on these cleaning dimensions, the first cleaning conditions are set as follows: power 55±5%, displacement speed 10000mm / s, frequency 300kHz, and engraving speed 8500mm / s; the second cleaning conditions are set as follows: power 60±5%, displacement speed 10000mm / s, frequency 300kHz, and engraving speed 10000mm / s.

[0048] After cleaning, the appearance is inspected under a microscope. The edge area outside the adhesive tape pasting area is checked for foil leakage. There are 3 foil leakage points in this edge area. The area of ​​the foil leakage point is ≤0.5mm², which is considered qualified. Then the subsequent application of protective adhesive tape is completed.

[0049] After protective tape is applied to the first and second protective slots respectively, the positive and negative electrode sheets enter the winding process. Because the protective tape is embedded in the first and second protective slots, it does not protrude beyond the electrode surface, significantly reducing the overall cell thickness compared to traditional surface-mount adhesive solutions and effectively improving energy density. Simultaneously, the first and second protective slots ensure stable adhesion of the tape during brush scraping, fundamentally solving the problem of tape detachment during the manufacturing process.

[0050] This application also provides a battery, including the cell structure described above. Since this battery employs all the technical solutions of all embodiments of the above cell structure, it at least includes all the technical effects brought about by the above technical solutions, and will not be elaborated upon here.

[0051] Compared with the prior art, the beneficial effects of the embodiments of this application are as follows: (1) By embedding the protective adhesive paper in the protective groove, the protective adhesive paper can be effectively prevented from protruding from the surface of the active material layer without increasing the thickness of the electrode, thus avoiding the protective adhesive paper from curling, shifting or even falling off completely. (2) By designing a through groove that penetrates the active material layer and a closed annular groove that protrudes from the through groove and surrounds the outer periphery of the through groove, the protective adhesive paper is stably embedded in the annular groove and is stably bonded with the current collector with a large adhesive force. While achieving stable bonding, the metal current collector can be avoided from being exposed, thus enhancing the safety and reliability of the battery cell. (3) Differentiate the design and quality control of the protective glue groove size on the positive and negative electrode sheets, reduce the loss of active lithium on the positive electrode sheet and improve the energy density of the battery cell under the premise of ensuring the process yield and the safety and reliability of the battery cell, and at the same time prevent lithium ions from accumulating in the protective groove of the negative electrode sheet to form lithium dendrites, which would cause the battery cell to fail. (4) To address the differences in the active materials and current collectors of the positive and negative electrode sheets, the protective glue tanks of the positive and negative electrode sheets are cleaned differently to improve the processing accuracy and batch production consistency during the cleaning process of the protective glue tanks, and at the same time improve the quality reliability of the protective glue tanks.

[0052] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and the present invention also intends to include these modifications and variations.

Claims

1. An electrode sheet, characterized in that, include: current collector; An active material layer covering the surface of the current collector; A protective groove for accommodating protective adhesive paper is provided along the edge of the electrode sheet; The protective groove includes a through groove and an annular groove; the annular groove is recessed inward from the end of the active material layer away from the current collector, and the inner bottom surface of the annular groove and the end of the active material layer near the current collector are spaced apart by the groove bottom thickness; the through groove penetrates the active material layer through the inner bottom surface of the annular groove, and there is a gap between the groove opening edge of the through groove and the outer edge of the annular groove on the same side.

2. The electrode sheet according to claim 1, characterized in that: The cutting dimension of the annular groove along the length of the electrode sheet is greater than the width of the protective adhesive paper; the depth of the annular groove is greater than the thickness of the protective adhesive paper.

3. An electrode sheet according to claim 2, characterized in that: The bottom thickness of the annular groove is 5~15μm.

4. An electrode sheet according to claim 1, characterized in that: Along the width direction of the electrode, the distance between the first edge of the electrode near the protective groove and the groove edge of the through groove on the same side is 4~5mm; the distance between the groove edge of the through groove away from the first edge and the outer edge of the annular groove on the same side is 2.5~3.5mm. Along the length of the electrode sheet, the distance between the edge of the groove opening and the outer edge of the annular groove on the same side is 2.5~3.5mm.

5. A battery cell structure, characterized in that, include: A positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; The positive electrode and / or the negative electrode comprises the electrode as described in any one of claims 1-4.

6. A cell structure according to claim 5, characterized in that: The positive electrode includes a first current collector, a positive active material layer covering both ends of the first current collector, and a first protective groove. The first protective groove includes a first through groove that completely penetrates the positive active material layer and a first annular groove cut from the positive active material layer away from the first current collector towards the first current collector. The bottom of the first annular groove completely covers the outer periphery of the first through groove.

7. A cell structure according to claim 6, characterized in that: An undercoating layer is provided between the first current collector and the positive electrode active material layer; the through groove and the orthographic projection of the undercoating layer on the end face of the first current collector at least partially overlap.

8. A cell structure according to claim 5, characterized in that: The negative electrode sheet includes a second current collector, a negative electrode active material layer covering both ends of the second current collector, and a second protective groove; the second protective groove includes a second through groove that completely penetrates the negative electrode active material layer and a second annular groove cut from one end of the negative electrode active material layer away from the second current collector toward the second current collector, the bottom of the second annular groove at least partially covering the outer periphery of the second through groove.

9. A cell structure according to claim 8, characterized in that: The bottom surface of the second annular groove is provided with an adhesive tape pasting area in the middle and an edge area outside the adhesive tape pasting area. The edge area accommodates no more than three foil-diffusing points, and the foil-diffusing area of ​​each foil-diffusing point is ≤0.5mm². 2 .

10. A battery, characterized in that, include: The cell structure according to any one of claims 5-9.

Images