Pole piece, roll core structure and battery

Abstract

The utility model relates to the technical field of lithium ion batteries, and discloses a pole piece, a roll core structure and a battery. The pole piece comprises a coating area for coating an active substance, a pasting area for pasting ending gummed paper and a tab welding area, wherein a plurality of groups of through holes are formed in the coating area at intervals; each group of penetrating holes are respectively positioned on each preset bending part of the pole piece; wherein the predetermined bending part is a pole piece part positioned in an R-angle area of the roll core after the pole piece is made into the roll core. According to the utility model, through the design that the through holes are punched in the R-angle region of each layer of the roll core on the pole piece, the electrolyte permeability of electrolyte in the R-angle region is improved, the electrolyte retention capacity of the battery cell is effectively increased, and the CB value of the R-angle region of the battery cell is improved, so that the cycle performance of the battery is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium-ion batteries, in particular to a pole piece, a winding core structure and a battery. Background Art

[0002] During the winding process of soft-pack lithium-ion batteries, due to stress concentration and high material density at the R corner (corner area), it is often difficult for the electrolyte to fully penetrate and retain, affecting the battery's liquid retention capacity and thus limiting the cycle performance of the battery cell.

[0003] Traditional winding core designs typically fail to optimize the R-corner region, resulting in uneven electrochemical reactions in this area. Consequently, improving electrolyte distribution in the R-corner region, thereby increasing overall cell fluid retention and cycle life, has become a technical challenge in current soft-pack lithium-ion battery design.

[0004] The above information is presented as background information only to assist with an understanding of the present disclosure and is not a determination or admission that any of the above may be applicable as prior art with respect to the present disclosure. Utility Model Content

[0005] The purpose of the present invention is to provide a pole piece, a winding core structure and a battery, so as to solve or at least partially solve the technical problems existing in the prior art.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a pole piece, comprising a coating area for coating an active material, a pasting area for pasting a finishing tape, and a tab welding area, wherein a plurality of groups of through holes are arranged at intervals on the coating area;

[0008] Each group of the through holes is respectively located on each predetermined bending portion of the pole piece;

[0009] The predetermined bending portion is the portion of the pole piece located in the R corner area of ​​the winding core after the pole piece is made into a winding core.

[0010] Optionally, each group of through holes includes a row of through holes evenly distributed along the width direction of the pole piece.

[0011] Optionally, the electrode is a positive electrode;

[0012] The thickness of the current collector of the positive electrode sheet is 3-20 μm, and the thickness of the active material coating applied on the coating area is 45-150 μm.

[0013] Optionally, the penetration hole is a circular through hole with a diameter of 0.5-1 mm.

[0014] Optionally, the two ends of the electrode are respectively provided with the adhesive areas; or,

[0015] The adhesive area is respectively provided at a middle section of the pole piece and at an end of the pole piece in the winding direction of the pole piece;

[0016] Wherein, the adhesive area is not coated with active substances.

[0017] Optionally, the spacing between adjacent predetermined bending portions increases along the winding direction of the pole piece.

[0018] In a second aspect, the present invention provides a winding core structure, which is formed by winding pole pieces and diaphragms stacked in sequence, wherein the positive pole piece in the pole pieces adopts a pole piece as described above.

[0019] Optionally, the negative electrode sheet, separator and positive electrode sheet in the electrode sheet are wound into a core.

[0020] In a third aspect, the present invention further provides a battery, comprising a winding core and pole tabs electrically connected to pole pieces of the winding core, wherein the winding core adopts a winding core structure as described above.

[0021] Optionally, the battery is a lithium-ion battery.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The pole piece provided by the utility model is designed with through holes punched in the R corner area of ​​each layer of the winding core on the pole piece, thereby improving the electrolyte permeability in the R corner area, effectively increasing the liquid retention capacity of the battery cell, and improving the CB value of the R corner area of ​​the battery cell, thereby improving the cycle performance of the battery.

[0024] The present invention has other features and advantages, which will be apparent from the accompanying drawings and subsequent detailed descriptions incorporated herein, or will be described in detail in the accompanying drawings and subsequent detailed descriptions incorporated herein, which together serve to explain the specific principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 work.

[0026] Figure 1 This is a schematic structural diagram of a pole piece provided in an embodiment of the present utility model.

[0027] Figure 2 This is a structural principle diagram of a winding core provided by an embodiment of the present utility model.

[0028] Figure 3 This is a schematic structural diagram of another pole piece provided by an embodiment of the present utility model.

[0029] In the figure: 10, winding core; 101, R corner area; 102, tape; 11, positive electrode sheet; 111, coating area; 112, pasting area; 113, penetration hole; 114, tab welding area; 12, negative electrode sheet; 21, positive tab; 22, negative tab. DETAILED DESCRIPTION

[0030] In order to explain in detail the possible application scenarios, technical principles, specific solutions that can be implemented, and the purpose and effects of this application, the following is a detailed description of the specific embodiments listed in conjunction with the accompanying drawings. The embodiments described herein are only used to more clearly illustrate the technical solutions of this application and are therefore only examples and are not intended to limit the scope of protection of this application.

[0031] References to "embodiments" herein mean that the specific features, structures, or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the word "embodiment" in various places in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or relevance to other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the various technical features mentioned in the embodiments can be combined in any manner to form a corresponding implementable technical solution.

[0032] Unless otherwise defined, the technical terms used herein have the same meanings as those generally understood by those skilled in the art to which this application belongs; the use of relevant terms herein is only for describing specific embodiments and is not intended to limit this application.

[0033] In the description of this application, the term "and / or" is used to describe a logical relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A exists, B exists, and both A and B exist. In addition, the character " / " in this document generally indicates that the objects before and after are in a logical "or" relationship.

[0034] In this application, terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual quantity, priority or sequence relationship between these entities or operations.

[0035] Without further limitations, in this application, the words "include", "comprise", "have" or other similar expressions used in the sentences are intended to cover non-exclusive inclusion. These expressions do not exclude the presence of additional elements in the process, method or product including the elements, so that the process, method or product including a series of elements may include not only those defined elements, but also other elements not explicitly listed, or elements inherent to such process, method or product.

[0036] Consistent with the understanding in the Examination Guidelines, in this application, expressions such as "greater than," "less than," and "exceed" are understood to exclude the number itself; expressions such as "above," "below," and "within" are understood to include the number itself. Furthermore, in the description of the embodiments of this application, "multiple" means more than two (including two), and similar expressions related to "multiple" are also understood in this manner, such as "multiple groups," "multiple times," etc., unless otherwise specifically defined.

[0037] In the description of the embodiments of the present application, the space-related expressions used, such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "vertical", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or position relationship based on the orientation or position relationship shown in the specific embodiments or drawings, and are only for the convenience of describing the specific embodiments of the present application or facilitating the reader's understanding, and do not indicate or imply that the device or component referred to must have a specific position, a specific orientation, or be constructed or operated in a specific orientation. Therefore, it should not be understood as a limitation on the embodiments of the present application.

[0038] Unless otherwise expressly specified or limited, in the description of the embodiments of the present application, the terms "installed", "connected", "connected", "fixed", "set", etc. used should be understood in a broad sense. For example, the "connection" can be a fixed connection, a detachable connection, or an integrated setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For those skilled in the art of the present application, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0039] Example 1:

[0040] See also Figure 1 , Figure 1 This is a schematic structural diagram of a pole piece provided in an embodiment of the present utility model.

[0041] like Figure 1 As shown, the electrode comprises a coating area 111 for coating active material, a pasting area (112) for pasting finishing tape, and an electrode tab welding area (114). The coating area 111 is provided with a plurality of groups of through holes 113 at intervals; each group of through holes 113 is located on each predetermined bending portion of the electrode.

[0042] The predetermined bending portion is the portion of the pole piece located in the R-angle region 101 of the winding core after the pole piece is made into the winding core 10 .

[0043] Please continue to refer to Figure 2 , Figure 2 This is a structural principle diagram of a winding core provided by an embodiment of the present utility model;

[0044] When the above-mentioned electrode structure is applied as the positive electrode sheet 11, since the punching position is located in the R corner area 101 of the winding core 10, the electrolyte can more fully penetrate into the interior of the winding core 10, forming a good liquid storage space, thereby improving the overall liquid retention of the battery cell. Compared with punching holes on the entire surface of the electrode sheet, this helps to improve the energy density of the battery cell design.

[0045] In addition, opening a through hole in the positive electrode sheet 11 is conducive to the uniform distribution of the electrolyte between the layers of the core 10, avoiding the accumulation or shortage of electrolyte in the R corner area 101, reducing local polarization, lowering the internal resistance, and thus improving the cycle performance.

[0046] Specifically, each group of through holes 113 includes a row of through holes 113 evenly distributed along the width direction of the pole piece;

[0047] In this embodiment, the thickness of the current collector of the positive electrode sheet 11 is 3-20 μm, and the thickness of the active material coating applied on the coating area 111 is 45-150 μm; accordingly, the through hole 113 is designed as a circular through hole with a diameter of 0.5-1 mm.

[0048] Specifically, the tail ends of the pole pieces are respectively provided with adhesive areas 112; or Figure 3 As shown, Figure 3 This is a schematic structural diagram of another positive electrode provided by an embodiment of the present invention, wherein a tab welding area (114) is provided in the middle section of the electrode and the electrode is arranged in the winding direction ( Figure 3 The end ( Figure 3 The right end of the middle electrode is provided with a pasting area 112; wherein, the tab welding area 114 and the pasting area 112 are not coated with active material.

[0049] It should be noted that the two pole pieces mentioned above are only different in application, so there are some deviations in structural design; Figure 1 To design the pole piece structure corresponding to the positive winding method, Figure 3 It is designed for the pole piece structure corresponding to the center placement method.

[0050] Specifically, the spacing between adjacent predetermined bending portions increases along the winding direction of the pole piece;

[0051] In this embodiment, after the pole piece is wound, it may form a cylindrical or elliptical cylindrical structure, and it needs to be flattened to form a cylindrical or elliptical structure. Figure 2 The winding core 10 shown;

[0052] like Figure 2 As shown, it can be understood that the distance between the bent parts on both sides of the pole piece portion wound in the innermost layer of the winding core 10 is the smallest; from the inside to the outside, the distance between the bent parts on both sides of the pole piece portion in the R angle area 101 gradually increases;

[0053] Therefore, when designing the pole piece, the spacing between the bent parts is gradually increased along the winding direction of the pole piece, so that after the pole piece is made into the winding core 10, the through hole 113 can be located just in the R corner area 101.

[0054] Furthermore, the preparation method of the electrode is as follows:

[0055] First, during the positive electrode batching process, 90% to 98% positive electrode active material and 0.5% to 3% conductive agent are added and stirred until a slurry with a viscosity within a certain range is prepared. The slurry is then coated on aluminum foil to form a film, dried, and cold-pressed. The electrode sheet is then cut into the required size for winding; that is, the thickness of the current collector (aluminum foil) is 3 to 20 μm, the thickness of the coating is 45 to 150 μm, and the diameter of the through-hole in the positive electrode sheet is 0.5 mm to 1 mm.

[0056] During the negative electrode batching process, 90% to 98% of the negative electrode active material and more than 1% of the thickener are added and stirred until the viscosity is within a certain range of the slurry. The slurry is then coated on the copper foil to form a film, dried, and cold pressed. The electrode is then cut into the required size for winding.

[0057] Then, the positive electrode sheet 11 is punched at the position of the predetermined bending portion (corresponding to the R corner area 101 of the winding core 10);

[0058] Then, the positive electrode sheet 11 and the negative electrode sheet 12 are respectively Figure 2 Welding of the positive electrode ear 21 and the negative electrode ear 22);

[0059] Finally, according to the conventional winding method of the soft-pack battery cell, the negative electrode sheet 12, the positive electrode sheet 11 and the two layers of separators are wound in sequence to obtain a winding core 10 with the positive electrode sheet 11 punched in the R corner area 101.

[0060] It should be noted that the punching position can be confirmed according to the trial production process of the winding core 10, and it is necessary to ensure that the punching position of the positive electrode sheet 11 is exactly located in the R corner area 101 of the winding core 10 after winding;

[0061] After the core 10 is prepared, it can be packaged, baked, and injected with electrolyte. After the electrolyte is injected and allowed to stand, the electrolyte will fully penetrate all layers of the battery cell and the R corner area 101.

[0062] In this embodiment, the through hole 113 can be suitable for different positive electrode sheet materials, including but not limited to lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide and mixed materials, and the punching process of the positive electrode sheet 11 will not affect the electrochemical performance and structural integrity of the battery cell.

[0063] Example 2:

[0064] This embodiment provides a battery, including a winding core 10 and a tab electrically connected to a pole piece of the winding core 10. Figure 2 As shown, the winding core structure is made by winding electrode sheets and diaphragms stacked in sequence, and the positive electrode sheet 11 in the electrode sheets adopts the electrode sheet described in the first embodiment.

[0065] Since the structures of the pole piece and the winding core 10 have been described in detail in the first embodiment, they will not be described again in this embodiment.

[0066] Specifically, one end of the negative electrode sheet 12 located outside the core structure is adhered to the surface of the core structure by means of an adhesive tape 102 .

[0067] Specifically, the battery is a lithium-ion battery.

[0068] In this embodiment, the design of opening a through hole in the positive electrode sheet 11 can effectively reduce the stress concentration phenomenon in the R corner area 101, prevent the positive electrode material from cracking or deforming due to excessive stress and thus causing the electrode sheet to break, and further enhance the stability of the battery structure.

[0069] As described above, the above embodiments 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 above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. However, 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 embodiments of the present invention.

Claims

1. A pole piece, comprising a coating area (111) for coating an active material, a pasting area (112) for pasting a finishing tape, and a tab welding area (114), characterized in that: The coating area (111) is provided with a plurality of groups of penetration holes (113) at intervals; Each group of penetration holes (113) is located on each predetermined bending portion of the pole piece; The predetermined bending portion is the portion of the pole piece located in the R angle region (101) of the winding core after the pole piece is made into the winding core (10).

2. A pole piece according to claim 1, characterized in that: Each group of penetration holes (113) comprises a row of penetration holes (113) uniformly distributed along the width direction of the pole piece.

3. A pole piece according to claim 1, characterized in that: The electrode is a positive electrode (11); The thickness of the current collector of the positive electrode sheet (11) is 3-20 μm, and the thickness of the active material coating applied on the coating area (111) is 45-150 μm.

4. A pole piece according to claim 3, characterized in that: The penetration hole (113) is a circular through hole with a diameter of 0.5-1 mm.

5. A pole piece according to claim 1, characterized in that: The tail ends of the pole pieces are respectively provided with the adhesive areas (112); The pasting area (112) and the tab welding area (114) are not coated with active material.

6. A pole piece according to claim 1, characterized in that: The spacing between adjacent predetermined bending portions increases along the winding direction of the pole piece.

7. A winding core structure, made by winding pole pieces and diaphragms stacked in sequence, characterized in that: The positive electrode (11) in the electrode is a electrode as described in any one of claims 1 to 6.

8. The winding core structure according to claim 7, characterized in that: One end of the negative electrode sheet (12) in the electrode sheet located outside the winding core structure is adhered to the surface of the winding core structure through an adhesive tape (102).

9. A battery comprising a winding core and a tab electrically connected to a pole piece of the winding core, characterized in that: The winding core adopts a winding core structure as described in claim 7 or 8.

10. A battery according to claim 9, characterized in that: The battery is a lithium-ion battery.

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