Bus plate and battery

Abstract

To provide a bus plate and a battery and to relate to the technical field of battery production and processing.SOLUTION: A battery includes a bus plate, one side of the bus plate has a plurality of weld loci for connection to jerry rolls, each welding locus is distributed in array in the circumferential direction of the bus plate, and the welding locus is a smooth wavy curve.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] This invention claims priority to a Chinese patent application filed with the China Patent Office on December 18, 2023 and bearing application number 202323461294.1, and an international application filed with the China Patent Office on July 26, 2024 and bearing application number PCT / CN2024 / 107791, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to the technical field of battery manufacturing processing, and in particular to bus plates and batteries. [Background technology]

[0003] Cylindrical batteries generally use laser welding to weld the battery bus plate and the jelly roll to ensure the strength of the connection and the overcurrent area between the pole and the connection piece. In the related art, the laser welding trajectory between the battery bus plate and the jelly roll can adopt a broken line welding trajectory. The broken line welding trajectory requires that the speed of the laser beam near the inflection point once decreases to zero and then increases from zero to accelerate. Alternatively, the laser welding trajectory between the battery bus plate and the jelly roll can adopt a spiral curve welding trajectory (shown in FIG. 1). Summary of the Invention [Problem to be solved by the invention]

[0004] In the broken line welding trajectory, the laser energy is accumulated in a large amount at the inflection point, which results in a large welding depth and the risk of welding penetration. Meanwhile, the spiral curve welding trajectory has multiple overlapping welding points, which are prone to over-welding at the overlapping welding points, and the structure is penetrated by welding. The above various problems reduce the welding quality of the battery in the related art. [Means for solving the problem]

[0005] The present invention provides a bus plate, the bus plate comprising a welding side and a back side provided opposite to each other, the welding side being configured to be welded to a jelly roll, and a welding locus presenting a smooth wavy curve being provided on the back side.

[0006] The present invention provides a battery, the battery including a jelly roll and the bus plate, the welding side of the bus plate being welded to a tab of the jelly roll, and the orthographic projection of the welding locus of the bus plate on the welding side overlapping the tab.

Advantages of the Invention

[0007] The bus plate according to the present invention is set to a smooth wavy curve that does not intersect or overlap the welding locus, making it difficult for inflection points to exist in the welding locus, reducing the welding energy at the inflection points, and avoiding penetration of the bus plate. It is also possible to avoid the presence of a plurality of overlapping points on the bus plate when adopting spiral welding in the related art and avoid the welding energy at the overlapping points on the bus plate being too large. Further, by arranging a plurality of welding loci uniformly on the bus plate, the connection between the bus plate and the jelly roll can be made stronger, the overcurrent area can be made larger, the situation of overwelding can be improved, and the welding quality can be enhanced.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0009] In the description of the present invention, the terms "first" and "second" are used only for the purpose of description and should not be understood as indicating or implying relative importance or indicating the number of indicated technical features. Thus, the features limited to "first" and "second" can explicitly or implicitly include one or more features. In the description of the present invention, "a plurality" means two or more unless otherwise particularly limited.

[0010] In related art, a battery bus plate includes a positive electrode bus plate and a negative electrode bus plate. It is necessary to weld between the positive electrode bus plate and the jelly roll, and it is also necessary to weld between the negative electrode bus plate and the jelly roll. Thereby, a battery pack for supplying power to a device that combines cells to supply power can be formed. The welding between the battery bus plate and the jelly roll is more uniform, the welding strength and overcurrent capacity of a plurality of welding points between the battery bus plate and the jelly roll are better, and the welding effect is better.

[0011] Since the welding tracks used in the connection structure between the battery bus plate and the jelly roll in related art are usually broken lines and spiral shapes, inflection points and overlapping points are likely to exist. As a result, over-welding occurs between the battery bus plate and the jelly roll.

[0012] As shown in FIGS. 2 and 3, FIG. 2 is a schematic structural diagram of a negative electrode bus plate according to an embodiment of the present invention, and FIG. 3 is a schematic structural diagram of a positive electrode bus plate according to an embodiment of the present invention. The present invention provides a bus plate having a welding side and a back side provided opposite to each other. The welding side is configured to be welded to the jelly roll 3, and a welding track 2 is provided on the back side. The welding track 2 presents a smooth wavy curve.

[0013] The smooth wavy curve may be any curve without inflection points and without overlap (non-intersecting), for example, it may be a sine curve, or a curve without inflection points composed of a straight line and a curve, or a random curve. It is understood that this is also possible.

[0014] In the related art, since the welding track is a bent straight line and there are a plurality of inflection points, in the welding process, the laser beam accelerates on the straight line and then becomes constant speed, decelerates immediately before the inflection point, and the speed of the laser beam drops to 0 when reaching the inflection point. After that, the speed of the laser beam needs to increase from 0. Therefore, at the inflection point, the energy of the laser beam accumulates and becomes large, and the depth of welding tends to become large, and there is a risk of welding through. On the other hand, when the welding track is set in a spiral shape, although there are no inflection points in the welding track, there are a plurality of overlapping points. The existence of overlapping points in the welding track means that the welding energy at that location is too high, and overwelding is likely to occur at that location. In both cases, overwelding may occur to some extent, which affects the welding effect.

[0015] The beneficial effects of the present invention are as follows. By setting the welding locus 2 as a smooth wavy curve that does not intersect or overlap (the wavy curve may be a smooth curve, may not be a smooth curve, and there may be inflection points in the non-smooth wavy curve), it becomes difficult for inflection points to exist in the welding locus 2, reduces the welding energy at the inflection points, and can avoid penetrating and breaking the bus plate. Also, it can avoid the existence of multiple overlapping points on the bus plate when adopting spiral welding in the related art, and can also avoid the welding energy being too large at the overlapping points on the bus plate. Further, by arranging a plurality of welding loci 2 uniformly on the bus plate, the connection between the bus plate and the jelly roll 3 can be made stronger, the overcurrent area can be made larger, the situation of over-welding can be improved, and the welding quality can be enhanced.

[0016] The bus plate in this embodiment is applied to the cylindrical cell of the steel case. Of course, it may also be applied to batteries of other shapes (for example, square).

[0017] In some embodiments of the present invention, as shown in FIGS. 4 and 5, FIG. 4 is another structural schematic diagram of the negative electrode bus plate according to the embodiment of the present invention, and FIG. 5 is another structural schematic diagram of the positive electrode bus plate according to the embodiment of the present invention. The welding locus 2 includes a plurality of semi-circular portions 21 and a plurality of straight portions 22, and the plurality of semi-circular portions 21 and the plurality of straight portions 22 are provided and connected alternately in sequence.

[0018] Here, being provided alternately means that the straight portion 22 and the semi-circular portion 21 are connected end to end. One end of a straight portion 22 is connected to one end of a semi-circular portion 21, and the other end of the straight portion 22 is connected to one end of another semi-circular portion 21.

[0019] Note that the semi-circular portion 21 is not limited to a semi-circular curve and may be a part of an elliptical curve. The straight portion 22 may be a straight line or a curve having a certain radian. Since the semi-circular portion 21 and the straight portion 22 need to be in contact, the entire welding locus is a smooth (without inflection points) curve, and this curve can be regarded as a wavy curve in a broad sense. However, the wavy curve is not limited to a curve composed of the straight portion 22 and the semi-circular portion 21.

[0020] It can be understood that the plurality of semi-circular portions 21 and the plurality of straight portions 22 are alternately provided and connected in sequence to form a wavy curve locus, and there are no overlapping points and inflection points on the locus, which is an optimized structure of an ordinary wavy arc.

[0021] In an embodiment of the present invention, the wavy curve is converted into the semi-circular portion 21 and the straight portion 22, and the semi-circular portion 21 and the straight portion 22 are alternately provided and connected, so that the width of the welding locus 2 (that is, the length of the wavy curve in the length direction of the straight portion 22, and further the length of the bus plate in the circumferential direction) can be made wider. Thereby, the area of the welding locus 2 on the surface of the bus plate can be made larger, and the welding contact surface can be made larger and more uniform. In this way, the connection strength between the bus plate and the jelly roll 3 is increased, the overcurrent area between the bus plate and the jelly roll 3 is increased, and the overall effective overcurrent area of the battery is increased. Therefore, there is no need to consider adding filler welding to the blank space.

[0022] In some embodiments of the present invention, as shown in FIGS. 4 and 5, the plurality of straight portions 22 are provided at intervals in parallel in sequence.

[0023] As can be understood, the fact that the plurality of straight portions 22 are provided at intervals in parallel in sequence does not necessarily mean that the lengths of the respective straight portions 22 are the same, and the lengths of the plurality of straight portions 22 in each welding locus 2 may be different.

[0024] Furthermore, the straight portion 22 may be a part of a circle (i.e., an arc) surrounding the center of the bus plate. If a plurality of arcs (i.e., straight portions 22) are parallel to each other, similarly, the diameters of the semi-circular portions 21 in the welding locus can be made to coincide.

[0025] By arranging the straight portions 22 parallel to each other, the diameter of the semi-circular portion 21 in the welding locus 2 on the surface of the bus plate can be maximized. Thereby, in the welding process, the laser beam can be bent more easily without decelerating, or can be bent smoothly with the lowest deceleration rate. Therefore, the dispersion of the welding energy values at each location of the welding locus 2 is minimized, the distribution of the welding energy at each location of the welding locus 2 becomes more uniform, and over-welding at the bent locations of the welding locus 2 is effectively prevented.

[0026] In some embodiments of the present invention, the welding locus 2 extends along the radial direction of the bus plate.

[0027] The fact that the welding locus 2 extends along the radial direction of the bus plate may be connected along the diameter direction of the bus plate, or may be offset by a certain angle with respect to the diameter direction of the bus plate. Thereby, one end of the welding locus 2 faces the center of the bus plate, and the other end of the welding locus 2 faces the edge of the bus plate.

[0028] By extending a plurality of welding loci 2 along the radial direction of the bus plate, the number of connection layers between the bus plate and the electrode tab on the jelly roll 3 can be increased, the connection strength between the bus plate and the jelly roll 3 after welding can be increased while increasing the over-current area between the bus plate and the jelly roll 3, and the over-current effect of the entire battery can be made better.

[0029] In some embodiments of the present invention, there are a plurality of welding loci 2, and each of the welding loci 2 is sequentially provided around the center of the bus plate.

[0030] The number of the welding tracks 2 arranged and distributed along the circumferential direction of the bus plate only needs to satisfy the welding strength and the overcurrent area between the bus plate and the jelly roll 3. Generally, 8 welding tracks may be provided. If the number exceeds 8, the welding efficiency will decrease. If the number is less than 8, the welding strength is likely to decrease. Installing multiple welding tracks 2 is to reduce the welding time between the bus plate and the jelly roll 3 in the battery.

[0031] It should be understood that in order to ensure a high overall welding strength and a large overall overcurrent area between the entire bus plate and the jelly roll 3, when the welding tracks 2 are arranged and distributed around the bus plate, it is necessary to make the distances between adjacent welding tracks 2 the same.

[0032] By arranging and distributing the welding tracks 2 along the circumferential direction of the bus plate, it is possible to significantly shorten the welding time while ensuring a sufficiently strong welding strength and a sufficiently large overcurrent area between the jelly roll and the bus plate. As a result, the efficiency of the entire welding process can be improved, and the efficiency of the entire battery manufacturing process can be improved.

[0033] In some embodiments of the present invention, the bus plate may be a positive bus plate or a negative bus plate, and the embodiments of the present invention do not limit this. In some embodiments, the bus plate may be a positive bus plate, and the positive bus plate includes a circular bus plate body 11 and a lead tab 12 extending from the bus plate body 11.

[0034] It should be noted that the shapes of the positive bus plate and the negative bus plate may be different. The positive bus plate includes the body 11 and the tab 12. However, the welding tracks on both the positive bus plate and the negative bus plate need to meet the requirement that there are no inflection points and overlapping points.

[0035] In some embodiments of the present invention, as shown in FIG. 6, FIG. 6 is another structural schematic diagram of a negative electrode bus plate according to an embodiment of the present invention, and the welding locus 2 is an annular closed wavy curve provided around the center of the bus plate.

[0036] The welding locus 2 may be an annular closed welding locus 2 surrounding the center of the bus plate. Similarly, the occurrence of inflection points and overlapping points on the welding locus 2 can be avoided. Thereby, the welding energy is too high due to the inflection points and overlapping points generated on the welding locus 2, causing a situation of overwelding, destroying the welding strength between the jelly roll 3 and the bus plate, and reducing the overcurrent area between the jelly roll 3 and the bus plate. This avoids the situation. Here, it is limited to examples of other embodiments where there are no inflection points and overlapping points on the curve.

[0037] In some embodiments, the bus plate is a copper sheet. The material of the bus plate may be a copper sheet provided with a plating layer, and the plating layer may be a chemical plating layer.

[0038] Some embodiments of the present invention can relatively reduce the internal resistance of the bus plate by setting the material of the bus plate as a copper sheet, and can reduce the heat generation situation existing during the operation of the bus plate. Thereby, the overcurrent loss of the bus plate and the jelly roll is reduced, and the conductive performance of the entire battery is improved.

[0039] The thickness of the bus plate may be determined according to actual needs and is not limited in the embodiments of the present invention. In some embodiments of the present invention, the thickness of the bus plate is 0.1 - 0.5 mm, and further, it may be 0.15 - 0.25 mm, for example, 0.15 mm, 0.20 mm, 0.25 mm, etc.

[0040] In some embodiments of the present invention, by setting the thickness of the bus plate to 0.1 - 0.5 mm, it is possible to avoid welding the bus plate or the jelly roll 3 during the welding process.

[0041] In some embodiments of the present invention, the welding locus 2 is a laser welding locus, and the laser beam can laser-weld the bus plate and the jelly roll 3 along the welding locus 2.

[0042] By adopting laser welding for the welding locus in the embodiments of the present invention, the welding quality can be improved.

[0043] In a second aspect, the present invention provides a battery. As shown in FIG. 7, FIG. 7 is a cross-sectional structural view of a battery according to an embodiment of the present invention. The battery includes a jelly roll 3 and a bus plate. The welding side of the bus plate is welded to the tab of the jelly roll 3, and the orthographic projection of the welding side of the welding locus 2 on the bus plate overlaps the tab. By providing the bus plate, the battery has all the beneficial effects of the bus plate, that is, there are no overlapping points and no inflection points on the welding locus between the bus plate and the jelly roll 3 in the battery, the welding energy at the inflection point is reduced, and it is possible to avoid penetrating the bus plate. It is also possible to avoid the situation where there are multiple overlapping points on the bus plate when spiral welding is adopted in the related art, and avoid the welding energy at the overlapping points on the bus plate being too large. Further, by arranging a plurality of welding loci 2 uniformly on the bus plate, the connection between the bus plate and the jelly roll 3 can be made stronger, the situation of over-welding can be improved, and the welding quality can be enhanced.

[0044] In some embodiments, as shown in FIG. 8, FIG. 8 is a schematic structural view of a tab according to an embodiment of the present invention. The jelly roll 3 is formed by winding a first electrode, a second electrode, and a separator sandwiched therebetween around a winding axis. The jelly roll 3 has a core portion and an outer peripheral surface.

[0045] The first electrode includes an active material coated portion and a non-coated portion along the axial direction of the winding axis. At least a part of the non-coated portion functions as a tab. The non-coated portion includes a first portion A adjacent to the core portion of the jelly roll 3, a second portion B adjacent to the outer peripheral surface of the jelly roll 3, and a third portion C located between the first portion A and the second portion B. The height of the first portion A and / or the second portion B is lower than the height of the third portion C along the axial direction of the winding axis.

[0046] The third portion C is divided into a plurality of individually foldable sections 31. The plurality of sections 31 form a folding surface area when folded in the radial direction of the jelly roll 3, and the folding surface area is the tab of the jelly roll 3. It can be understood that the first portion A and the second portion B can be divided.

[0047] The folding surface area includes a uniform layer number section and a decreasing layer number section along the direction from the core side to the outer peripheral side. The number of layers of the sections 31 in the uniform layer number section is uniform. The decreasing layer number section is located outside the uniform layer number section, and the number of layers of the sections 31 in the decreasing layer number section decreases towards the outer peripheral side.

[0048] It can be understood that the second electrode also includes an active material coated portion and a non-coated portion along the axial direction of the winding axis. The non-coated portion has at least a part functioning as a tab, and includes a first portion A adjacent to the core portion of the jelly roll 3, a second portion B adjacent to the outer peripheral surface of the jelly roll 3, and a third portion C located between the first portion A and the second portion B. The height of the first portion A and / or the second portion B is lower than the height of the third portion C along the axial direction of the winding axis.

[0049] The third portion C is divided into a plurality of individually foldable sections 31. The plurality of sections 31 form a folding surface area when folded in the radial direction of the jelly roll 3, and the folding surface area is the tab of the jelly roll 3. It can be understood that the first portion A and the second portion B can be divided.

[0050] The bent surface area includes a uniform number of layers section and a decreasing number of layers section along the direction from the core side to the outer peripheral side. The number of layers of section 31 in the uniform number of layers section is uniform. The decreasing number of layers section is located outside the uniform number of layers section, and the number of layers of section 31 in the decreasing number of layers section decreases as it goes toward the outer peripheral side.

[0051] In some embodiments, the number of layers of section 31 in the uniform number of layers section is 10 or more.

[0052] It should be understood that the region where the number of layers of section 31 is 10 or more may be used as the welding target region.

[0053] In some embodiments, the orthographic projection area of the welding locus 2 on the bent surface area is completely located within the uniform number of layers region.

[0054] The uniform number of layers section is the region where the number of layers of the bent surface area is the largest. In this way, when the current collector plate and the tab of the jelly roll 3 are welded, it is possible to avoid welding penetration of the tab layer formed by stacking a plurality of tabs of the jelly roll 3.

[0055] In some embodiments, the width of the welding locus 2 is larger than the width of section 31.

[0056] In this way, it can be guaranteed that the welding locus 2 always welds to two adjacent tabs in the same circle.

[0057] In some embodiments, along the radial direction of the jelly roll, at least a part of the welding locus 2 is welded to two adjacent sections 31 in the same circle.

[0058] In this way, it can be guaranteed that the welding locus 2 always welds to two adjacent tabs in the same circle.

[0059] As shown in FIG. 7, the welding side of the bus plate is welded to the tab of the jelly roll 3. The material of the positive tab of the jelly roll 3 is aluminum foil, and the material of the negative tab of the jelly roll 3 is copper foil.

Explanation of Reference Signs

[0060] 11. Bus plate body 12. Lead tab 2. Welding trace 21. Semi-circular part 22. Straight part 3. Jelly roll 31. Section A. First part B. Second part C. Third part.

Claims

1. A bus plate, The welding machine has a welding side and a back side that are provided opposite to each other, the welding side is configured to be welded to a jelly roll (3), and the back side is provided with a welding track (2) that exhibits a smooth wavy curve. Bus plate.

2. The welding trajectory (2) includes a plurality of semicircular portions (21) and a plurality of straight portions (22), and the plurality of semicircular portions (21) and the plurality of straight portions (22) are alternately provided and connected in sequence. The bus plate of claim 1 .

3. The plurality of straight portions (22) are arranged in parallel and spaced apart order. The bus plate of claim 2.

4. The welding locus (2) extends along a radial direction of the bus plate. The bus plate of claim 1 .

5. the welding trajectory (2) is multiple, and each of the welding trajectories (2) is provided in sequence around the center of the bus plate; The bus plate of claim 4.

6. The bus plate is a positive bus plate, and the positive bus plate includes a bus plate body (11) and a lead tab (12) extending from the bus plate body (11). The bus plate according to any one of claims 1 to 5.

7. The welding trajectory (2) is a circular closed wavy curve arranged around the center of the bus plate. The bus plate according to any one of claims 1 to 5.

8. The thickness of the bus plate is 0.1 to 0.5 mm. The bus plate according to any one of claims 1 to 5.

9. a bus plate according to any one of claims 1 to 5, wherein a welding side of the bus plate is welded to a tab of the jelly roll, and an orthogonal projection of a welding locus on the bus plate on the welding side overlaps with the tab; battery.

10. The jelly roll (3) is formed by winding a first electrode, a second electrode, and a separator sandwiched therebetween around a winding axis, and the jelly roll (3) has a core portion and an outer peripheral surface, In the axial direction of the winding shaft, the first electrode includes an active material coated portion and an uncoated portion, at least a part of the uncoated portion functions as a tab, the uncoated portion includes a first portion (A) adjacent to a core portion of the jelly roll (3), a second portion (B) adjacent to an outer peripheral surface of the jelly roll (3), and a third portion (C) located between the first portion (A) and the second portion (B), and in the axial direction of the winding shaft, a height of the first portion (A) and / or the second portion (B) is less than a height of the third portion (C), the third portion (C) is divided into a plurality of individually foldable sections (31), the plurality of sections (31) defining folding surface areas when folded radially along the jelly roll (3), the folding surface areas being the tabs of the jelly roll (3); In a direction from the core portion side toward the outer periphery side, the folded surface region includes a uniform lamination number section in which the number of laminations of the section (31) is uniform, and a lamination number decreasing section located on the outer periphery side of the uniform lamination number section in which the number of laminations of the section (31) decreases toward the outer periphery side.

10. The battery of claim 9.

11. The number of layers of the section (31) in the uniform layer number section is 10 or more. The battery of claim 10.

12. The orthogonal projection area of ​​the welding trajectory (2) on the bent surface region is completely located within the uniform layer number section. The battery of claim 10.

13. The width of the welding track (2) is greater than the width of the section (31); The battery of claim 10.

14. In the radial direction of the jelly roll, the welding track (2) is welded to two adjacent sections (31) at least partially in the same circle. The battery of claim 10.

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