Pole piece and battery
By pre-die cutting and cutting on the pole piece, the problem of turning out during the winding of the pole piece is solved, the safety performance of the roll core is enhanced, and the safety hazards of the battery are reduced.
Patent Information
- Application Number
- CN202422370283.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-27
- Publication Date
- 2025-08-22
- Estimated Expiration
- 2034-09-27
AI Technical Summary
In the prior art, the pole sheet is prone to tilt out during winding, resulting in the drop of active substances and burrs piercing the inner layer of the aluminum-plastic film, causing safety hazards such as short circuits and internal corrosion.
A plurality of cuts are pre-dieed on the pole sheet, especially in the easy-to-turn out area. The first cut and the second cut are formed on the foil and the active layer through the die-cutting process. After the pole sheet is wound into a core, the stress is transmitted to both sides of the width direction of the core through the cut, enhancing the binding force and reducing the risk of tilting out.
It effectively reduces the tilt of the pole in the easy-to-turn out area, improves the safety performance of the coil core, and reduces the safety risks of the battery.
Smart Images
Figure CN223260606U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of batteries, in particular to a pole piece and a battery. Background Art
[0002] Currently, the tail of the positive electrode sheet is equipped with a series of sections, namely, double-sided foil sections, single-sided foil sections, and blank foil sections, arranged in this order along the head-to-tail direction. The double-sided foil section has active material applied to both sides of the foil, the single-sided foil section has active material applied to one side and not to the other, and the blank foil section has no active material applied to either side. These single-sided and blank foil sections are primarily used to ensure that when the positive electrode sheet is wound into a core, the outer layer of the core is finished with the blank foil section.
[0003] Reference Figure 5-8 When the electrode is bent, the single-sided foil segment needs to bend around the arc portion of the core 10. Along the width direction of the core 10, the closer the single-sided foil segment is to the arc portion on both sides of the core 10, the less likely it is to fold outward. The single-sided aluminum foil in the middle of the width direction 100 of the core is subject to less restraint force, especially the dotted area in the figure is prone to bulging outward, which is called the easy-to-fold-out area 300; in the prior art, the easy-to-fold-out area 300 on both sides of the thickness direction 200 of the core is bonded to the upper and lower sides of the core 10 with tape 400 to reinforce the position of the electrode. However, before the tape 400 is bonded, the easy-to-fold-out area 300 may have already experienced the pole piece flipping phenomenon. After the tape 400 is bonded, the flipping phenomenon of the foil will only be aggravated.
[0004] The single-sided foil segment after being turned inside out may cause the active material to fall off, and the burrs on the electrode may easily pierce the PP layer of the inner layer of the aluminum-plastic film, causing short circuits and internal corrosion, which may pose a safety hazard to the battery. Summary of the Invention
[0005] The embodiments of the present invention provide a pole piece and a battery to reduce the potential safety hazard of the battery caused by the pole piece turning outward in the prior art.
[0006] To solve the above technical problems, on the one hand, an embodiment of the present invention provides a pole piece, comprising a foil, a first active layer, and a second active layer, wherein the foil is in the shape of an elongated strip, the first active layer and the second active layer are coated on both side surfaces of the foil in the thickness direction, the foil has a first end face and a second end face opposite to each other along its length direction, the first active layer and the second active layer extend along the length direction of the foil, and the length of the first active layer is greater than the length of the second active layer; along the length direction of the foil, an end face of the first active layer close to the first end face is closer to the first end face than an end face of the second active layer close to the first end face, and an area on the foil between an end face of the first active layer close to the first end face and an end face of the second active layer close to the first end face is a single-sided foil area;
[0007] A first incision is provided on both sides of the single-sided foil area in the width direction, the first incision penetrates the single-sided foil area along the thickness direction of the single-sided foil area, and the outer opening of the first incision penetrates one side edge of the single-sided foil area in the width direction, and a second incision corresponding to the first incision is provided on both sides of the width direction of the first active layer, the second incision penetrates the first active layer along the thickness direction of the first active layer, and the outer opening of the second incision penetrates one side edge of the first active layer in the width direction; the first incision is aligned with the corresponding second incision and is combined to form a pole piece incision.
[0008] Optionally, four of the first incisions and four of the second incisions are respectively provided, wherein two of the first incisions are spaced apart on one side of the width direction of the foil; and the other two of the first incisions are spaced apart on the other side of the width direction of the foil.
[0009] Optionally, the first incision and the second incision are arc-shaped incisions.
[0010] Optionally, the opening of the first incision gradually shrinks along one side of the width direction of the foil where it is located toward the middle of the width direction of the foil; the opening of the second incision gradually shrinks along one side of the width direction of the foil where it is located toward the middle of the width direction of the foil.
[0011] Optionally, the edge of the first incision is in one of the shapes of a catenary, an arc, or a semi-ellipse; the edge of the second incision is in one of the shapes of a catenary, an arc, or a semi-ellipse.
[0012] On the other hand, an embodiment of the present invention also provides a winding core, including a positive electrode sheet, a negative electrode sheet and a separator, at least one of the positive electrode sheet and the negative electrode sheet is the above-mentioned electrode sheet, the separator is arranged between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet, the negative electrode sheet and the separator are wound to form a square winding core, the thickness direction, height direction and width direction of the winding core are perpendicular to each other, the height direction of the winding core is parallel to the width direction of the electrode sheet, the first incision and the second incision are located in the middle of the width direction of the winding core, and the first incision and the second incision are located on both sides of the height direction of the winding core.
[0013] Optionally, the opening length of the first incision along the length direction of the foil is a, the width of the winding core is d, and a / d×100%=5%-10%.
[0014] Optionally, an opening length of the first incision along the width direction of the foil is b, b / d×100%=5%-7%.
[0015] Optionally, a is 5-10 mm; b is 5-7 mm.
[0016] On the other hand, an embodiment of the present invention further provides a battery, comprising a shell and the aforementioned winding core, wherein the winding core is disposed in the shell.
[0017] The present invention provides a pole piece and battery. Prior to winding the pole piece, multiple cutouts are pre-die-cut through a die-cutting process. After the pole piece is wound into a core, the cutouts are located in the areas of the core most susceptible to external folding. The stress generated by the pole piece during winding can be transferred to both sides of the core in the width direction through the cutouts. The pole pieces on both sides of the core have a greater restraining force and are less likely to fold, thereby reducing the risk of external folding of the pole piece in areas prone to folding, thereby improving the safety of the core and reducing potential safety hazards in the battery. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.
[0019] Figure 1 This is a schematic structural diagram of a pole piece according to an embodiment of the present invention;
[0020] Figure 2 This is a schematic diagram of one side surface of a pole piece according to an embodiment of the present invention;
[0021] Figure 3This is a front structural diagram of a winding core according to an embodiment of the present invention;
[0022] Figure 4 This is a schematic diagram of the reverse structure of the winding core of one embodiment of the present utility model;
[0023] Figure 5 It is a top view of the winding core in the prior art;
[0024] Figure 6 It is a front view of a winding core in the prior art;
[0025] Figure 7 It is a side view schematic diagram of the winding core after the adhesive tape is bonded in the prior art;
[0026] Figure 8 This is a front view of the core after the tape is bonded in the prior art.
[0027] Reference numerals: 10, core; 100, width direction of core; 200, thickness direction of core; 300, easy-to-turn-outward area; 400, adhesive tape; 500, height direction of core;
[0028] 1. Foil; 2. First active layer; 3. Second active layer; 41. Empty foil area; 42. Single-sided foil area; 5. First incision; 6. Second incision; 7. Pole tab; 8. Pole piece incision. DETAILED DESCRIPTION
[0029] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.
[0030] In the description of the present invention, it should be understood that the terms "longitudinal," "radial," "length," "width," "thickness," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.
[0031] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.
[0032] Reference Figure 1-4 , an embodiment of the present utility model provides a pole piece for being wound into a winding core 10, comprising a foil 1, a first active layer 2 and a second active layer 3, the foil 1 being in the shape of an elongated strip, the first active layer 2 and the second active layer 3 being coated on both side surfaces in the thickness direction of the foil 1, the foil 1 having a first end face and a second end face opposite to each other along its length direction, the first active layer 2 and the second active layer 3 extending along the length direction of the foil 1, the length of the first active layer 2 being greater than the length of the second active layer 3; along the length direction of the foil 1, the end face of the first active layer 2 on one side close to the first end face is closer to the first end face than the end face of the second active layer 3 on one side close to the first end face, the area on the foil 1 between the end face of the first active layer 2 on one side close to the first end face and the end face of the second active layer 3 on one side close to the first end face is a single-sided foil area 42;
[0033] Typically, an active material is applied to the surface of a foil 1 to form an active material layer. The active material coating width is equal to the width of the foil 1, and the active material coating length is less than the length of the foil 1. The coating length of the first active layer 2 is greater than the coating length of the second active layer 3, resulting in one side of the foil being coated with the active material, while the other side is not. The area of the foil not coated with the active material is referred to as a single-sided foil area. Because the coating lengths of the first active layer 2 and the second active layer 3 are both less than the length of the foil 1, both sides of the foil 1 along the thickness direction are not coated with an active layer. The area of the foil not coated with active material forms a blank foil area 41.
[0034] Reference Figure 1 That is, in this embodiment, the electrode is divided into the following three areas according to whether the two side surfaces of the foil 1 are coated with active material: the first area is that both sides of the foil 1 in the thickness direction are coated with active material; the second area is that one side of the foil 1 in the thickness direction is coated with active material, and the other side is not coated with active material (single-sided foil area 42); the third area is that both sides of the foil 1 in the thickness direction are not coated with active material (empty foil area 41).
[0035] A first incision 5 is provided on both sides of the single-sided foil area 42 in the width direction, and the first incision 5 penetrates the single-sided foil area 42 along the thickness direction of the single-sided foil area 42, and the outer opening of the first incision 5 penetrates one side edge of the single-sided foil area 42 in the width direction. A second incision 6 is provided on both sides of the first active layer 2 in the width direction, and the second incision 6 penetrates the first active layer 2 along the thickness direction of the first active layer 2, and the outer opening of the second incision 6 penetrates one side edge of the width direction of the first active layer 2. The first incision 5 and the corresponding second incision 6 on the same side are aligned and combined to form a pole piece incision 8.
[0036] The electrode cutouts 8 are located at the area of the winding core 10 most prone to folding. The stress generated by the electrode during winding can be transferred through the electrode cutouts 8 to both sides of the winding core 10 in the width direction, thereby reducing the occurrence of folding in the middle of the winding core 10, which is prone to folding. This improves the safety of the winding core and reduces potential safety hazards of the battery. The electrode sheets on both sides of the winding core 10 have greater restraint force and are less likely to fold.
[0037] In this embodiment, the alignment of the first incision 5 and the second incision 6 means that the first incision 5 and the second incision 6 overlap in the orthographic projection of the surface of one side in the thickness direction of the foil 1. Specifically, in actual production, the foil 1 coated with the active material is die-cut along the thickness direction of the foil 1 through a die-cutting process, and the foil 1 and a portion of the first active layer 2 on its surface are die-cut away. The die-cut portion of the foil 1 is the first incision 5, and the die-cut portion of the first active layer 2 is the second incision 6. At this time, the cut-away area on the electrode is the electrode incision 8.
[0038] As an example, four first incisions 5 and four second incisions 6 are respectively provided, wherein two first incisions 5 are spaced apart on one side of the width direction of the foil 1 ; and the other two first incisions 5 are spaced apart on the other side of the width direction of the foil 1 .
[0039] Referring to the accompanying drawings, in this embodiment, after the pole piece is wound into a square core 10, two second incisions 6 and two first incisions 5 are respectively provided on one side (front side) in the thickness direction of the core 10. The second incision 6 is located on the outside of the outermost pole segment of the core 10, and the first incision 5 is located on the inner side of the outermost pole segment of the core 10 compared to the second incision 6. One of the two second incisions 6 is located on one side in the height direction of the core 10, and the other of the two second incisions 6 is located on the other side in the height direction of the core 10. The two second incisions 6 are located in the middle of the width direction of the core 10. Two first incisions 5 and two second incisions 6 are also provided on the other side (the reverse side) of the core 10 in the thickness direction. The second incisions 6 are located outside the outermost polar section of the core 10, while the first incisions 5 are located inside the outermost polar section of the core 10. One of the two second incisions 6 is located on one side of the core 10 in the height direction, and the other is located on the other side of the core 10 in the height direction. The two second incisions 6 are located in the middle of the core 10 in the width direction. The four first incisions 5 and second incisions 6 can completely remove the easy-to-turn-out region 300 on both sides of the core 10 in the thickness direction.
[0040] In this embodiment, two second cutouts 6 arranged one above the other on the same side of the winding core 10 in the thickness direction are symmetrically arranged with respect to the center line of the winding core 10 in the width direction.
[0041] As an example, the first incision 5 and the second incision 6 are arc-shaped incisions.
[0042] Specifically, the outer opening of the first cutout 5 gradually narrows along one side of the width of the foil 1 where it is located toward the middle of the width of the foil 1; the outer opening of the second cutout 6 gradually narrows along one side of the width of the foil 1 where it is located toward the middle of the width of the foil 1. More specifically, the edge of the first cutout 5 is one of a catenary, an arc, or a semi-elliptical shape; and the edge of the second cutout 6 is one of a catenary, an arc, or a semi-elliptical shape.
[0043] Since the closer to the edges of both ends of the foil 1 in the width direction, the easier it is to turn outward, the outer opening of the first incision 5 is enlarged, so that the angle between the outer opening and the width direction of the foil 1 increases, and the force of the pole piece along the width direction of the foil 1 is transferred more to both sides of the width direction of the core 10. In this embodiment, the semi-elliptical shape can be die-cut out with the long axis of the ellipse as the reference, or the semi-elliptical shape can be die-cut out with the short axis of the ellipse as the reference. The arc shape is also preferably a semicircle. In this way, the stress on the pole piece can be transferred to both sides of the width direction of the core 10 through the semi-elliptical, semi-circular or catenary-shaped first incision 5, and the above-mentioned arc-shaped edge can increase the stability of the first incision 5 and the second incision 6 in a principle similar to that of an arch bridge, which is conducive to the release of stress, and can also reduce the occurrence of tearing in the die-cut area (first incision 5 or second incision 6).
[0044] On the other hand, an embodiment of the present invention also provides a winding core, including a positive electrode sheet, a negative electrode sheet and a separator, at least one of the positive electrode sheet and the negative electrode sheet is the above-mentioned electrode sheet, the separator is arranged between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet, the negative electrode sheet and the separator are wound to form a square winding core, the thickness direction, height direction and width direction of the winding core are perpendicular to each other, the height direction of the winding core is parallel to the width direction of the electrode sheet, the first incision and the second incision are located in the middle of the width direction of the winding core, and the first incision and the second incision are located on both sides of the height direction of the winding core.
[0045] In this embodiment, the electrode sheet of the above embodiment is a positive electrode sheet. In principle, the first incision 5 and the second incision 6 can be applied to the negative electrode sheet. However, if used on the negative electrode sheet, the area of the positive electrode sheet will be larger, resulting in greater capacity loss. Therefore, they are not used on the negative electrode sheet for the time being, and are only applied to the positive electrode sheet on the outermost circle of the winding core.
[0046] As an example, the opening length of the first incision 5 along the length direction of the foil 1 is a, that is, the length of the first incision 5 along the width direction of the core 10 is a, the width of the core 10 is d, a / d×100%=5%-10%.
[0047] Optionally, the opening length of the first incision 5 along the width direction of the foil 1 is b, that is, the opening length of the first incision 5 along the height direction of the winding core 10 is b, b / d×100%=5%-7%.
[0048] Specifically, a is 5-10 mm; b is 5-7 mm.
[0049] In this embodiment, for winding cores 10 of different models and sizes, the sizes of the first incision 5 and the second incision 6 can be adaptively changed according to the above-mentioned relationship. Technicians can adjust the sizes of the first incision 5 and the second incision 6 for different batteries, thereby increasing the range of applicable batteries of the first incision 5 and the second incision 6.
[0050] As in the prior art, the winding core 10 also includes a pole ear 7. A small portion of the active layer is removed from the two side surfaces of the pole piece to form a first blank area and a second blank area facing each other, so that the foil 1 in the first blank area and the second blank area is exposed to the outside, and the pole ear 7 is welded to one of the first blank area and the second blank area.
[0051] In one embodiment, the present invention further provides a battery, including a housing and the aforementioned winding core 10 , wherein the winding core 10 is disposed in the housing.
[0052] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.
Claims
1. A pole piece, characterized in that: The invention comprises a foil (1), a first active layer (2) and a second active layer (3), wherein the foil (1) is in the shape of an elongated strip, the first active layer (2) and the second active layer (3) are coated on both side surfaces of the foil (1) in the thickness direction, the foil (1) has a first end face and a second end face opposite to each other along its length direction, the first active layer (2) and the second active layer (3) extend along the length direction of the foil (1), and the length of the first active layer (2) is greater than the length of the second active layer (3); along the length direction of the foil (1), the end face of the first active layer (2) close to the first end face is closer to the first end face than the end face of the second active layer (3) close to the first end face, and the area on the foil (1) between the end face of the first active layer (2) close to the first end face and the end face of the second active layer (3) close to the first end face is a single-sided foil area (42); A first incision (5) is provided on both sides of the single-sided foil area (42) in the width direction, the first incision (5) penetrates the single-sided foil area (42) along the thickness direction of the single-sided foil area (42), and the outer opening of the first incision (5) penetrates one side edge of the single-sided foil area (42) in the width direction; Second cutouts (6) corresponding to the first cutouts (5) are provided on both sides of the first active layer (2) in the width direction, the second cutouts (6) penetrate the first active layer (2) along the thickness direction of the first active layer (2), and the outer opening of the second cutout (6) penetrates one side edge of the first active layer (2) in the width direction; The first incision (5) and the corresponding second incision (6) are aligned and combined to form a pole piece incision (8).
2. The pole piece according to claim 1, characterized in that: Four of the first incisions (5) and four of the second incisions (6) are provided, two of which are spaced apart on one side of the width direction of the foil (1); and the other two of which are spaced apart on the other side of the width direction of the foil (1).
3. The pole piece according to claim 2, characterized in that: The first incision (5) and the second incision (6) are arc-shaped incisions.
4. The pole piece according to claim 1, characterized in that: The opening of the first incision (5) gradually decreases along one side of the width direction of the foil (1) where it is located toward the middle of the width direction of the foil (1); the opening of the second incision (6) gradually decreases along one side of the width direction of the foil (1) where it is located toward the middle of the width direction of the foil (1).
5. The pole piece according to claim 3, characterized in that: The edge of the first incision (5) is in the shape of a catenary, an arc, or a semi-ellipse; the edge of the second incision (6) is in the shape of a catenary, an arc, or a semi-ellipse.
6. A winding core, characterized in that: The invention comprises a positive electrode sheet, a negative electrode sheet and a separator, at least one of the positive electrode sheet and the negative electrode sheet is a sheet according to any one of claims 1 to 5, the separator is arranged between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet, the negative electrode sheet and the separator are wound to form a square core (10), the thickness direction, the height direction and the width direction of the core (10) are perpendicular to each other, the height direction of the core (10) is parallel to the width direction of the electrode sheet, the first incision (5) and the second incision (6) are located in the middle of the width direction of the core (10), and the first incision (5) and the second incision (6) are located on both sides of the height direction of the core (10).
7. The winding core according to claim 6, characterized in that The opening length of the first incision (5) along the length direction of the foil (1) is a, the width of the winding core (10) is d, and a / d×100%=5%-10%.
8. The winding core according to claim 7, characterized in that The opening length of the first cut (5) along the length direction of the foil (1) is b, b / d×100%=5%-7%.
9. The winding core according to claim 8, characterized in that a is 5-10mm; b is 5-7mm.
10. A battery, characterized in that: It comprises a shell and a winding core (10) according to any one of claims 6 to 9, wherein the winding core (10) is arranged in the shell.