Battery pole piece and battery cell

Abstract

The utility model belongs to the technical field of batteries, and discloses a battery pole piece and a battery cell, the battery pole piece comprises a pole piece body, an embossed area is arranged on the pole piece body, the embossed area at least comprises two kinds of embossments with different depths along the direction from the winding starting point to the winding ending point of the pole piece body, the embossing depth close to the winding starting point is larger than the embossing depth away from the winding starting point. The battery pole piece can effectively reduce the lithium precipitation phenomenon of the battery, and is favorable for improving the capacity of the battery and prolonging the cycle life.

Description

Technical Field

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

[0002] In recent years, with the rapid rise of new energy vehicles, the lithium battery industry has developed rapidly to a great extent, and users have put forward higher requirements for the performance indicators of lithium batteries such as capacity and cycle life. For square aluminum shell lithium batteries, the battery cell is composed of pole pieces that are folded and wound with each other. In order to prevent the pole pieces of wound lithium-ion batteries from wrinkling and lithium precipitation, the pole pieces need to be embossed. Usually, the pole pieces are long and have many layers. In the prior art, since the embossing rollers use the same air pressure, the surface of the pole pieces has exactly the same embossing depth. However, when the embossing depth is the same, the inner pole piece is subjected to a large internal stress after winding, and the gaps generated by the embossing are not enough to buffer the expansion of the inner pole piece. Therefore, the inner pole piece is prone to wrinkles. At the same time, it is easy to cause the spacing between the outer pole pieces to be too large, and the lithium ion transmission path increases, which leads to lithium precipitation at the R corner of the outer pole piece (the corner position of the battery cell).

[0003] Therefore, it is urgent to propose battery electrodes and battery cells to solve the above problems. Utility Model Content

[0004] The utility model aims to provide a battery pole piece and a battery cell, wherein the battery pole piece can effectively reduce the lithium deposition phenomenon of the battery, help to improve the battery capacity and increase the cycle life.

[0005] To achieve this purpose, the utility model adopts the following technical solutions:

[0006] A battery pole piece includes a pole piece body, on which an embossing area is arranged. Along the direction from the winding starting point to the end point of the pole piece body, the embossing area includes at least two embossings with different depths, and the embossing depth close to the winding starting point is greater than the embossing depth far from the winding starting point.

[0007] Optionally, the embossing area includes a first embossing area, a second embossing area and a third embossing area arranged along the winding direction of the pole piece body from the starting point to the end point, the embossing depth on the first embossing area is d1, the embossing depth on the second embossing area is d2, the embossing depth on the third embossing area is d3, and d1>d2>d3.

[0008] Optionally, along the winding direction from the starting point to the end point of the pole piece body, the length of the first embossed area is S1, the length of the second embossed area is S2, the length of the third embossed area is S3, and the length of the pole piece body is a;

[0009] S1=2 / 5×a; S2=3 / 10×a; S3=3 / 10×a.

[0010] Optionally, along the direction from the starting point to the end point of winding the pole piece body, the depth d of the embossing decreases linearly with the length S of the embossing area.

[0011] Optionally, along the winding starting point to the end point of the pole piece body, the embossing depth at the initial position of the embossing area is d1, the embossing depth at the end position of the embossing area is d3, and the length of the pole piece body is a;

[0012] The embossing depth at a location where the embossing area has a length of S is d: d=(d3-d1) / a×S+d1.

[0013] Optionally, a non-embossed area is further provided on the pole piece body, and the embossed area is located on one side of the winding starting point of the pole piece body, and the non-embossed area and the embossed area are arranged adjacent to each other.

[0014] Optionally, the total length S0 of the embossed area is less than or equal to 1 / 2×the length a of the pole piece body. ， Along the winding direction from the starting point to the end point of the pole piece body, the depth d of the embossing decreases linearly with the length S of the embossing area.

[0015] Optionally, the embossing depth at the initial position of the embossing area is 0.1 to 0.15 times the thickness of the pole piece body.

[0016] Optionally, the embossing depth at the end position of the embossing area is 0.01 to 0.09 times the thickness of the pole piece body.

[0017] The utility model aims to provide a battery cell, which can effectively reduce the lithium deposition phenomenon of the battery, help to improve the battery capacity and increase the cycle life.

[0018] To achieve this purpose, the utility model adopts the following technical solutions:

[0019] A battery cell comprises a separator and the above-mentioned battery pole pieces, wherein the battery pole pieces comprise a positive pole piece and a negative pole piece, the separator is arranged between the positive pole piece and the negative pole piece to form a core body, and the core body is arranged in a wound manner.

[0020] Beneficial effects:

[0021] The battery pole piece provided by the utility model has different embossing depths from the pole piece body winding start point to the end point, and the embossing depth is larger on the side close to the winding start point. The battery cell formed by winding the battery contact piece with this structure has a smaller embossing size on the outer circle than on the inner circle. Accordingly, the gap between two adjacent circles of battery pole pieces is smaller, thereby effectively improving the problem of battery lithium deposition caused by the large gap between the outer circle pole pieces of the traditional battery cell, which helps to increase the capacity of the lithium battery and increase the cycle life.

[0022] The utility model also provides a battery cell, which adopts the above-mentioned battery pole piece. The embossing depth of the outer ring of the battery cell is smaller than the embossing depth of the inner ring. Therefore, the internal stress of the inner ring pole piece after winding can be reduced, and the expansion of the inner ring pole piece can be effectively alleviated to avoid wrinkling of the pole piece. At the same time, the spacing between the outer rings is prevented from being too large, which leads to an increase in the lithium ion transmission path, thereby avoiding lithium precipitation at the R angle of the outer ring pole piece. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in 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 the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0024] Figure 1 It is a schematic diagram of the structure of the pole piece body provided in the first embodiment of the utility model;

[0025] Figure 2 It is a schematic diagram of the structure of a battery cell provided in Embodiment 1 of the present utility model;

[0026] Figure 3 It is a side view of the pole piece body provided in the second embodiment of the utility model;

[0027] Figure 4 It is a schematic diagram of the structure of the pole piece body provided in the third embodiment of the present utility model.

[0028] In the figure:

[0029] 100, pole piece body; 200, embossed area; 210, first embossed area; 220, second embossed area; 230, third embossed area; 300, non-embossed area. DETAILED DESCRIPTION

[0030] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0031] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions, and the first feature "above", "above" and "above" the second feature include the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. The first feature "below", "below" and "below" the second feature include the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0032] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0034] The present embodiment provides a battery electrode, including a electrode body 100, on which an embossing area 200 is arranged. Along the direction from the starting point to the end point of winding of the electrode body 100 (the X-axis direction in the figure), the embossing area 200 includes at least two embossings with different depths, and the embossing depth close to the winding starting point is greater than the embossing depth away from the winding starting point.

[0035] The embossing depth of the battery pole piece from the winding start point to the end point of the pole piece body 100 is different, and the embossing depth is larger on the side close to the winding start point. The battery cell formed by winding the battery contact piece with this structure has a smaller embossing size on the outer circle than on the inner circle. Accordingly, the gap between two adjacent circles of battery pole pieces is smaller, thereby effectively improving the problem of battery lithium deposition caused by the large gap between the outer circle pole pieces of the traditional battery cell, which helps to increase the capacity of the lithium battery and increase the cycle life.

[0036] Optionally, an embossing roller with controllable pressure is used for embossing operation, and the pressure of the embossing roller is changed by adjusting the pressure through a cylinder. Pressure regulation and position regulation of the embossing roller are mature existing technologies in this field and will not be described in detail here.

[0037] Embodiment 1

[0038] See also Figure 1 The embossing area 200 includes a first embossing area 210, a second embossing area 220 and a third embossing area 230 arranged along the winding starting point to the end point of the pole piece body 100. The embossing depth on the first embossing area 210 is d1, the embossing depth on the second embossing area 220 is d2, and the embossing depth on the third embossing area 230 is d3, and d1>d2>d3.

[0039] Correspondingly, assuming that the pressures of the embossing roller in the first embossing area 210, the second embossing area 220 and the third embossing area 230 are P1, P2 and P3 respectively, then P1>P2>P3.

[0040] The first embossing area 210, the second embossing area 220 and the third embossing area 230 are all composed of multiple embossings of the same depth arranged in a matrix, that is, the first embossing area 210, the second embossing area 220 and the third embossing area 230 all include multiple columns of embossings spaced apart along the length direction of the pole piece body 100, and each column includes multiple embossings spaced apart along the width direction of the pole piece body 100.

[0041] In other embodiments, the embossing area 200 may further include a fourth embossing area or a fifth embossing area, etc. Optionally, d1, d2 and d3 may be in a linear decreasing relationship.

[0042] In this embodiment, along the winding direction from the starting point to the end point of the pole piece body 100, the length of the first embossed area 210 is S1, the length of the second embossed area 220 is S2, the length of the third embossed area 230 is S3, and the length of the pole piece body 100 is a, then, S1 = 2 / 5 × a; S2 = 3 / 10 × a; S3 = 3 / 10 × a. That is, S1: S2: S3 = 4: 3: 3.

[0043] In other embodiments, S1:S2:S3 may also be 3:3:4 or 3:4:3, etc., which can be set according to specific usage requirements.

[0044] In this embodiment, the first embossing area 210, the second embossing area 220 and the third embossing area 230 are arranged adjacent to each other. In other embodiments, the first embossing area 210, the second embossing area 220 and the third embossing area 230 may also be arranged at intervals.

[0045] Optionally, the embossing depth at the initial position of the embossing area 200 is 0.1 to 0.15 times the thickness of the pole piece body 100. Exemplarily, the embossing depth at the initial position of the embossing area 200 is 0.1, 0.11, 0.12, 0.13, 0.14 or 0.15 times the thickness of the pole piece body 100.

[0046] Optionally, the embossing depth at the end position of the embossing area 200 is 0.01 to 0.09 times the thickness of the pole piece body 100. Exemplarily, the embossing depth at the end position of the embossing area 200 is 0.01, 0.03, 0.05, 0.07 or 0.09 times the thickness of the pole piece body 100.

[0047] See also Figure 2 This embodiment also provides a battery cell, including a diaphragm and the above-mentioned battery pole pieces, the battery pole pieces include a positive pole piece and a negative pole piece, the diaphragm is arranged between the positive pole piece and the negative pole piece to form a core body, and the core body is wound.

[0048] The battery cell adopts the above-mentioned battery pole piece. The embossing depth of the outer ring of the battery cell is smaller than that of the inner ring. Therefore, the internal stress of the inner ring pole piece after winding can be reduced, and the expansion of the inner ring pole piece can be effectively alleviated to avoid wrinkling of the pole piece. At the same time, the spacing between the outer rings is prevented from being too large, which leads to an increase in the lithium ion transmission path, thereby avoiding lithium deposition at the R corner of the outer ring pole piece.

[0049] Embodiment 2

[0050] See also Figure 3 , along the winding starting point to the end point of the pole piece body 100, the embossing depth d decreases linearly with the length S of the embossing area 200.

[0051] For example, along the winding direction from the starting point to the end point of the pole piece body 100, the embossing depth at the initial position of the embossing area 200 is d1, and the embossing depth at the end position of the embossing area 200 is d3. The length of the pole piece body 100 is a, and the embossing depth at the embossing area 200 where the length is S is d, then, d = (d3-d1) / a×S+d1.

[0052] Accordingly, the relationship between the pressure P of the embossing roller and the length S of the embossing area 200 is P=0.095-0.015 / a×S. Optionally, the pressure P of the embossing roller ranges from 0.08Mpa to 0.095Mpa. For example, the pressure P of the embossing roller can be 0.08Mpa, 0.085Mpa, 0.09Mpa or 0.095Mpa.

[0053] Optionally, the embossing depth at the initial position of the embossing area 200 is 0.1 to 0.15 times the thickness of the pole piece body 100. Exemplarily, the embossing depth at the initial position of the embossing area 200 is 0.1, 0.11, 0.12, 0.13, 0.14 or 0.15 times the thickness of the pole piece body 100.

[0054] Optionally, the embossing depth at the end position of the embossing area 200 is 0.01 to 0.09 times the thickness of the pole piece body 100. Exemplarily, the embossing depth at the end position of the embossing area 200 is 0.01, 0.03, 0.05, 0.07 or 0.09 times the thickness of the pole piece body 100.

[0055] This embodiment also provides a battery cell, including a separator and the above-mentioned battery pole pieces, the battery pole pieces include a positive pole piece and a negative pole piece, the separator is arranged between the positive pole piece and the negative pole piece to form a core body, and the core body is wound.

[0056] The battery cell adopts the above-mentioned battery pole piece. The embossing depth of the outer ring of the battery cell is smaller than that of the inner ring. Therefore, the internal stress of the inner ring pole piece after winding can be reduced, and the expansion of the inner ring pole piece can be effectively alleviated to avoid wrinkling of the pole piece. At the same time, the spacing between the outer rings is prevented from being too large, which leads to an increase in the lithium ion transmission path, thereby avoiding lithium deposition at the R corner of the outer ring pole piece.

[0057] Embodiment 3

[0058] See also Figure 4 The pole piece body 100 is provided with an embossed area 200 and a non-embossed area 300. The embossed area 200 is located on one side of the winding start point of the pole piece body 100, and the non-embossed area 300 and the embossed area 200 are arranged adjacent to each other. In the non-embossed area 300, the pressure P of the embossing roller is canceled, and the pole piece body 100 is not embossed in the non-embossed area 300, that is, the outer ring of the winding core is not embossed.

[0059] Optionally, the total length S0 of the embossed area 200 is less than or equal to 1 / 2×the length a of the pole piece body 100 ， Along the winding direction from the starting point to the end point of the pole piece body 100, the embossing depth d decreases linearly with the length S of the embossing area 200.

[0060] For example, the total length S0 of the embossing area 200 may be 1 / 2a, 1 / 3a, 3 / 10a or 2 / 5a, etc. Optionally, in the embossing area 200, the pressure P of the embossing roller decreases linearly.

[0061] Optionally, the embossing depth at the initial position of the embossing area 200 is 0.1 to 0.15 times the thickness of the pole piece body 100. Exemplarily, the embossing depth at the initial position of the embossing area 200 is 0.1, 0.11, 0.12, 0.13, 0.14 or 0.15 times the thickness of the pole piece body 100.

[0062] Optionally, the embossing depth at the end position of the embossing area 200 is 0.01 to 0.09 times the thickness of the pole piece body 100. Exemplarily, the embossing depth at the end position of the embossing area 200 is 0.01, 0.03, 0.05, 0.07 or 0.09 times the thickness of the pole piece body 100.

[0063] This embodiment also provides a battery cell, including a separator and the above-mentioned battery pole pieces, the battery pole pieces include a positive pole piece and a negative pole piece, the separator is arranged between the positive pole piece and the negative pole piece to form a core body, and the core body is wound.

[0064] The battery cell adopts the above-mentioned battery pole piece. The embossing depth of the outer ring of the battery cell is smaller than that of the inner ring. Therefore, the internal stress of the inner ring pole piece after winding can be reduced, and the expansion of the inner ring pole piece can be effectively alleviated to avoid wrinkling of the pole piece. At the same time, the spacing between the outer rings is prevented from being too large, which leads to an increase in the lithium ion transmission path, thereby avoiding lithium deposition at the R corner of the outer ring pole piece.

[0065] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the scope of protection of the present invention. It is not necessary and impossible to list all implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the scope of protection of the claims of the present invention.

Claims

1. A battery pole piece, characterized in that: The invention comprises a pole piece body (100), wherein an embossing area (200) is arranged on the pole piece body (100), and along the direction from the winding starting point to the end point of the pole piece body (100), the embossing area (200) comprises at least two embossings of different depths, and the embossing depth close to the winding starting point is greater than the embossing depth far from the winding starting point.

2. The battery electrode according to claim 1, characterized in that: The embossing area (200) comprises a first embossing area (210), a second embossing area (220) and a third embossing area (230) arranged along the winding direction from the starting point to the end point of the pole piece body (100), the embossing depth on the first embossing area (210) is d1, the embossing depth on the second embossing area (220) is d2, the embossing depth on the third embossing area (230) is d3, and d1>d2>d3.

3. The battery pole piece according to claim 2, characterized in that: The length of the first embossed area (210) is S1, the length of the second embossed area (220) is S2, the length of the third embossed area (230) is S3, and the length of the pole piece body (100) is a; S1=2 / 5×a; S2=3 / 10×a; S3=3 / 10×a.

4. The battery pole piece according to claim 1, characterized in that: The depth d of the embossing decreases linearly with the length S of the embossing area (200).

5. The battery pole piece according to claim 4, characterized in that: Along the winding direction from the starting point to the end point of the pole piece body (100), the embossing depth at the initial position of the embossing area (200) is d1, the embossing depth at the end position of the embossing area (200) is d3, and the length of the pole piece body (100) is a; The embossing depth at a location where the length of the embossing area (200) is S is d: d = (d3-d1) / a×S+d1.

6. The battery pole piece according to claim 1, characterized in that: A non-embossed area (300) is also provided on the pole piece body (100), the embossed area (200) is located on one side of the winding start point of the pole piece body (100), and the non-embossed area (300) and the embossed area (200) are arranged adjacent to each other.

7. The battery pole piece according to claim 6, characterized in that: The total length S0 of the embossed area (200) is less than or equal to 1 / 2×the length a of the pole piece body (100) ， Along the direction from the winding start point to the end point of the pole piece body (100), the depth d of the embossing decreases linearly with the length S of the embossing area (200).

8. The battery pole piece according to claim 1, characterized in that: The embossing depth at the initial position of the embossing area (200) is 0.1 to 0.15 times the thickness of the pole piece body (100).

9. The battery pole piece according to claim 1, characterized in that: The embossing depth at the end position of the embossing area (200) is 0.01 to 0.09 times the thickness of the pole piece body (100).

10. A battery cell, characterized in that: It comprises a diaphragm and a battery electrode sheet as described in any one of claims 1 to 9, wherein the battery electrode sheet comprises a positive electrode sheet and a negative electrode sheet, the diaphragm is arranged between the positive electrode sheet and the negative electrode sheet to form a core body, and the core body is wound.

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