Winding type battery cell

Abstract

The utility model discloses a winding type battery cell. The negative active material layer of the negative plate is provided with the lug boss in the corner region, so that the lithium embedding space of the negative active material layer in the corner region is increased, namely, the CB value of the battery cell main body in the corner region is increased, the lithium precipitation risk of the negative plate in the corner region is reduced, and the battery cell main body is enabled to be in the corner region; a larger gap exists between the negative electrode active material layer and the positive electrode plate in the area outside the lug boss, and the electrolyte can better infiltrate the corner area of the battery cell main body through the gap, so that the ion dynamic performance of the corner area is improved, and the lithium precipitation risk of the negative electrode plate in the corner area is reduced.

Description

Technical Field

[0001] This utility model relates to batteries, and more particularly to a wound battery cell. Background Technology

[0002] Some existing lithium batteries contain a wound cell and electrolyte within their casing. The wound cell includes an electrode assembly, which is wound to form the cell body. The electrode assembly includes a positive electrode, a separator, and a negative electrode. The electrolyte wets the wound cell. The cell body has a flat area and corner areas located on both sides of the flat area. During normal use, the negative electrode is prone to lithium plating in the corner areas, affecting the stability of the wound cell. Utility Model Content

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a wound battery cell that can reduce the risk of lithium plating in the corner area of ​​the negative electrode.

[0004] A wound battery cell according to an embodiment of the present invention includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode. The electrode assembly is wound to form a battery cell body. The battery cell body has a flat region and two corner regions. The flat region is located between the two corner regions. The negative electrode includes a negative current collector and a negative active material layer. The negative active material layer is disposed on the negative current collector. The negative active material layer has protrusions in the corner regions.

[0005] The wound battery cell according to the embodiments of the present invention has at least the following beneficial effects: the negative electrode active material layer of the negative electrode sheet has a protrusion in the corner area, which increases the lithium intercalation space of the negative electrode active material layer in the corner area, that is, increases the CB value of the battery cell body in the corner area, reduces the risk of lithium plating of the negative electrode sheet in the corner area, and makes the negative electrode active material layer in the corner area of ​​the battery cell body have a larger gap with the positive electrode sheet in the area other than the protrusion. The electrolyte can better wet the corner area of ​​the battery cell body through the gap, thereby improving the ion dynamics performance of the corner area and reducing the risk of lithium plating of the negative electrode sheet in the corner area.

[0006] According to some embodiments of the present invention, the negative electrode active material layer is provided with at least two protrusions at intervals in each corner region.

[0007] According to some embodiments of the present invention, the negative electrode active material layer includes a main sheet portion and a protrusion portion. The protrusion portion is connected to the side of the main sheet portion away from the negative electrode current collector. The protrusion portion is strip-shaped, and the width of the protrusion portion is the same as the width of the main sheet portion. The negative electrode active material layer is provided with at least two protrusion portions, and all the protrusion portions are arranged at intervals along the length direction of the negative electrode sheet.

[0008] According to some embodiments of this utility model, the thickness of the main body sheet is A, and the thickness of the protrusion is B, satisfying B≤1 / 3A.

[0009] According to some embodiments of the present invention, the thickness of the protrusion is 10μm≤B≤20μm.

[0010] According to some embodiments of the present invention, the protrusion has a rectangular, trapezoidal, triangular or arc-shaped cross-section in the direction perpendicular to the width of the negative electrode sheet.

[0011] According to some embodiments of the present invention, the negative electrode current collector is provided with negative electrode active material layers on both sides, and at least one of the negative electrode active material layers is provided with the protrusion in the corner area.

[0012] According to some embodiments of this utility model, the radius of the negative electrode active material layer in the corner area is R, and the dimension of the protrusion along the length direction of the negative electrode sheet is C, satisfying C≤πR.

[0013] According to some embodiments of this utility model, the dimension C of the protrusion along the length direction of the negative electrode sheet satisfies: C = 10 mm.

[0014] According to some embodiments of the present invention, the length dimension of the negative electrode sheet in the flat region is D, and the distance between two adjacent protrusions along the length direction of the negative electrode sheet is E, satisfying E≤D.

[0015] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0016] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0017] Figure 1 This is a cross-sectional schematic diagram of a wound battery cell according to an embodiment of the present utility model;

[0018] Figure 2 This is an embodiment of the present utility model. Figure 1 A magnified view of a portion of point F;

[0019] Figure 3 This is a three-dimensional schematic diagram of the negative electrode sheet in the corner area according to an embodiment of the present invention;

[0020] Figure 4 This is a side view of the negative electrode sheet in the corner area according to the first embodiment of the present invention;

[0021] Figure 5 This is a side view of the negative electrode sheet in the corner area according to the second embodiment of the present invention;

[0022] Figure 6 This is a side view of the negative electrode sheet in the corner area according to the third embodiment of the present invention;

[0023] Figure 7 This is a side view of the negative electrode sheet in the corner area according to the fourth embodiment of the present invention.

[0024] Figure label:

[0025] Positive electrode 100;

[0026] Negative electrode sheet 200, negative electrode current collector 210, negative electrode active material layer 220, protrusion 221, main body sheet 222;

[0027] Diaphragm 300;

[0028] Straight area 410, corner area 420. Detailed Implementation

[0029] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0030] In the description of this utility model, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0031] In the description of this utility model, "multiple" refers to two or more. The use of "first" and "second" is for distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features or their sequential relationship.

[0032] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0033] There are also some existing lithium batteries whose positive electrode 100 includes a positive current collector and a positive active material layer. In the corner region 420, the positive active material layer has a groove. The groove can reduce the capacity of the positive electrode 100, thereby reducing lithium plating in the corner region 420 and improving the wetting effect of the cell body in the corner region 420.

[0034] Reference Figures 1 to 7 The wound battery cell of this utility model embodiment includes an electrode assembly. The electrode assembly includes a positive electrode 100, a negative electrode 200, and a separator 300 disposed between the positive electrode 100 and the negative electrode 200. The electrode assembly is wound to form a battery cell body. The battery cell body has a straight region 410 and two corner regions 420. The straight region 410 is located between the two corner regions 420. The negative electrode 200 includes a negative current collector 210 and a negative active material layer 220. The negative active material layer 220 is disposed on the negative current collector 210. The negative active material layer 220 has a protrusion 221 in the corner region 420.

[0035] The negative electrode active material layer 220 of the negative electrode sheet 200 has a protrusion 221 in the corner region 420, which increases the lithium intercalation space of the negative electrode active material layer 220 in the corner region 420, that is, increases the CB value of the cell body in the corner region 420, reduces the risk of lithium plating of the negative electrode sheet 200 in the corner region 420, and makes the area of ​​the negative electrode active material layer 220 outside the protrusion 221 in the corner region 420 of the cell body larger and the positive electrode sheet 100. The electrolyte can better wet the corner region 420 of the cell body through the gap, thereby improving the ion dynamics performance of the corner region 420 and reducing the risk of lithium plating of the negative electrode sheet 200 in the corner region 420.

[0036] In this embodiment, the negative electrode active material layer 220 has two or more protrusions 221 spaced apart in each corner region 420. The presence of multiple protrusions 221 in each corner region 420 of the negative electrode active material layer 220 allows for a relatively reasonable distribution of the increased lithium intercalation capacity of the negative electrode sheet 200 in the corner region 420, and also results in a relatively reasonable distribution of voids formed in the area outside the protrusions 221 of the negative electrode active material layer 220.

[0037] Specifically, the active material layer may have one, two, three or more protrusions 221 in each corner area 420, which can be selected by those skilled in the art according to actual needs.

[0038] In an embodiment, the negative electrode active material layer 220 includes a main sheet portion 222 and a protrusion portion 221. The protrusion portion 221 is connected to the side of the main sheet portion 222 away from the negative electrode current collector 210. The protrusion portion 221 is strip-shaped, and the width of the protrusion portion 221 is the same as the width of the main sheet portion 222. The negative electrode active material layer 220 is provided with two or more protrusion portions 221, and all the protrusion portions 221 are arranged at intervals along the length direction of the negative electrode sheet 200. The width of the protrusion 221 is equal to the width of the main body sheet 222, that is, the end of the protrusion 221 is aligned with the width side of the main body sheet 222, and the protrusions 221 are spaced apart along the length of the negative electrode sheet 200, so that the protrusions 221 are relatively evenly distributed in the corner region 420 of the negative electrode sheet 200, thereby relatively evenly improving the lithium intercalation capability of the negative electrode sheet 200 in the corner region 420; and so that the negative electrode active material layer 220 is also relatively evenly distributed in the area other than the protrusions 221 in the corner region 420, thereby relatively evenly improving the wetting effect of the electrolyte on the corner region 420.

[0039] In this embodiment, the thickness of the main sheet 222 is A, and the thickness of the protrusion 221 is B, satisfying B ≤ 1 / 3A. If the thickness of the protrusion 221 is too large, it may encroach on the space of the positive electrode 100, affecting the energy density of the battery; if the thickness of the protrusion 221 is too small, the effect of the protrusion 221 on improving the lithium intercalation capacity of the negative electrode 200 in the corner region 420 is not significant, and the effect of improving the electrolyte wetting effect on the corner region 420 is not significant. Therefore, the thickness of the protrusion 221 is selected according to the above-mentioned dimensions, which can relatively significantly improve the lithium intercalation capacity of the negative electrode 200 in the corner region 420, improve the CB value of the positive electrode 100 and the negative electrode 200 in the corner region 420, and significantly improve the electrolyte wetting effect on the corner region 420, while reducing the impact on the battery energy density.

[0040] In this embodiment, the thickness of the protrusion 221 is 10μm≤B≤20μm, which is a relatively reasonable thickness and results in good overall performance. Specifically, the thickness of the protrusion 221 can be selected from, for example, 10μm, 12μm, 14μm, 16μm, 18μm, or 20μm, or other values ​​within the range. Those skilled in the art can configure it according to actual needs.

[0041] In this embodiment, the protrusion 221 has a rectangular, trapezoidal, triangular, or arc-shaped cross-section perpendicular to the width of the negative electrode 200, which provides good performance and is relatively simple to manufacture. It is conceivable that in other embodiments, the protrusion 221 may have other shapes in its cross-section perpendicular to the width of the negative electrode 200, and those skilled in the art can configure it according to actual needs.

[0042] In this embodiment, negative electrode active material layers 220 are provided on both sides of the negative electrode current collector 210, and one of the negative electrode active material layers 220 has a protrusion 221 in the corner region 420. Since a wound battery cell typically has one positive electrode 100 and one negative electrode 200, providing a protrusion 221 in one of the active material layers of the negative electrode 200 can suppress lithium plating of the negative electrode 200 in the corner region 420 and improve the wetting ability of the electrolyte in the corner region 420. It is understood that in some embodiments, both negative electrode active material layers 220 of the negative electrode 200 may have a protrusion 221 in the corner region 420.

[0043] Specifically, in wound battery cells, lithium plating typically occurs on the negative electrode active material layer 220 outside the negative electrode sheet 200. Therefore, protrusions 221 are usually provided on the negative electrode active material layer 220 outside the negative electrode sheet 200 to more effectively suppress lithium plating in the corner region 420. The negative electrode active material layer 220 outside the negative electrode sheet 200 refers to the negative electrode active material layer 220 on the side of the negative electrode current collector 210 away from the winding center.

[0044] In this embodiment, the radius of the negative electrode active material layer 220 in the corner region 420 is R, and the dimension of the protrusion 221 along the length direction of the negative electrode sheet 200 is C, satisfying C≤πR. The dimension of the protrusion 221 along the length direction of the negative electrode sheet 200 does not exceed the range of the corner region 420, and the layout is relatively reasonable.

[0045] In this embodiment, the dimension C of the protrusion 221 along the length of the negative electrode 200 satisfies: C = 10 mm. If the dimension of the protrusion 221 along the length of the negative electrode 200 is too large, the area of ​​the negative electrode 200 outside the protrusion 221 in the corner region 420 will be too small, affecting the wetting effect of the electrolyte on the corner region 420. If the dimension of the protrusion 221 along the length of the negative electrode 200 is too small, the improvement in the lithium intercalation capacity of the negative electrode 200 in the corner region 420 will not be significant. The aforementioned dimension of the protrusion 221 along the length of the negative electrode 200 is relatively reasonable, resulting in a better overall performance.

[0046] In this embodiment, the length of the negative electrode 200 in the flat region 410 is D, and the distance between two adjacent protrusions 221 along the length of the negative electrode 200 is E, satisfying E≤D. The distance between the adjacent protrusions 221 is neither too large nor too small, and the layout is relatively reasonable. The protrusions 221 can be arranged only in the corner region 420, without needing to be arranged in the flat region 410.

[0047] Specifically, the distance E between two adjacent protrusions 221 along the length of the negative electrode 200 is usually 60mm, which results in a better overall effect.

[0048] Specifically, the positive electrode 100 includes a positive current collector and a positive active material layer. The positive active material layer is disposed in the positive current collector. The positive active material layer can also be provided with grooves at the corner region 420 to increase the CB value between the positive electrode 100 and the negative electrode 200 at the corner region 420, reduce the risk of lithium plating, and the grooves can form larger gaps to improve the wetting effect of the electrolyte on the corner region 420.

[0049] Specifically, during the production of the negative electrode sheet 200 in this embodiment, the main body portion 222 of the negative electrode active material layer 220 can be coated on the negative electrode current collector 210 first. Then, the protrusions 221 of the negative electrode active material layer 220 can be intermittently coated on the main body portion 222 by intermittent coating, thereby reducing the waste of negative electrode active material and improving production efficiency.

[0050] Specifically, this utility model also discloses a battery using the above-mentioned wound cell. Due to the use of the wound cell, the impact of lithium plating on the battery can be reduced, and the battery's stability in use can be improved.

[0051] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0052] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A wound cell, characterized by, The application relates to a battery electrode plate assembly. The application relates to a battery electrode plate assembly.

2. The wound cell of claim 1, wherein: The application relates to a battery electrode plate assembly.

3. The wound cell of claim 1, wherein: The application relates to a battery electrode plate assembly.

4. The wound cell of claim 3, wherein: The application relates to a battery electrode plate assembly.

5. The wound cell according to claim 4, characterized in that: The application relates to a battery electrode plate assembly.

6. The wound cell of claim 3, wherein: The application relates to a battery electrode plate assembly.

7. The wound cell of claim 1, wherein: The application relates to a battery electrode plate assembly.

8. The wound cell of claim 1, wherein: The application relates to a battery electrode plate assembly.

9. The wound cell of claim 8, wherein: The application relates to a battery electrode plate assembly.

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