Welding structure of power battery bottom shell and power battery

Abstract

The utility model discloses a welding structure of a power battery bottom shell, which is characterized in that at least one annular welding part protruding towards the inner side of a power battery is arranged in the middle of the bottom shell, the annular welding part has a first thickness, other areas on the bottom shell except the annular welding part have a second thickness, and the first thickness is smaller than the second thickness. The power battery further comprises a naked battery cell and a negative current collecting plate connected with the naked battery cell, the negative current collecting plate is arranged corresponding to the bottom shell, and a protruding part protruding towards the bottom shell is arranged in the middle of the negative current collecting plate corresponding to the annular welding part. And the convex part of the negative current collecting plate is attached to the annular welding part of the bottom shell and is connected with the annular welding part in a laser penetration welding manner. According to the utility model, the convex part and the annular welding part are preferentially contacted and attached, so that better fusion depth consistency and effective open-flow area can be realized; in addition, the thickness of the annular welding part is reduced, and welding can be carried out by adopting laser with relatively low power to avoid the risk that the naked battery cell is possibly damaged by high-power laser.

Description

Technical Field

[0001] The utility model relates to the field of power batteries, in particular to a welding structure of a power battery bottom shell and a power battery. Background Art

[0002] With the increasingly serious crisis of non-renewable energy and the strong guidance of national policies, electric vehicles have become the main trend of the future development of the automobile industry. As an important component of electric vehicles, power batteries have the highest installed capacity in the field of electric vehicles due to their advantages such as small size, high energy density and green environmental protection. At present, lithium-ion / sodium-ion cylindrical power batteries have gradually become the mainstream products in the new energy industry due to their high energy density, good capacity consistency, and support for high-rate charging and discharging. With the popularization of new energy vehicles, people have put forward higher requirements for fast charging travel (i.e., high-rate fast charging of power batteries). At the same time, more and more manufacturers have begun to explore the bottom shell penetration welding process to solve the needs of fast charging travel. Common problems: 1. The bottom of the common shell of cylindrical power batteries is thicker, and a larger laser welding power is required to weld through, resulting in the risk that the laser energy fluctuation may damage the bare battery cell; 2. After the bare battery cell of the cylindrical battery is flattened or flattened, the end of the foil is uneven, or the collector plate is slightly deformed, resulting in a gap when the collector plate and the bottom shell are adapted, and the consistency of the laser penetration welding depth is poor, and the effective flow area cannot be guaranteed. Summary of the invention

[0003] The utility model aims to provide a welding structure of a power battery bottom shell and a power battery, so as to solve the problem that the existing bottom shell is thick, causing damage to bare cells during laser penetration welding, and the problem that a gap occurs when the current collecting plate and the bottom shell are adapted.

[0004] In order to achieve the above-mentioned purpose, the utility model provides a welding structure of a power battery bottom shell, wherein the middle part of the bottom shell is provided with at least one annular welding portion protruding toward the inner side of the power battery, the annular welding portion has a first thickness, and other areas on the bottom shell except the annular welding portion have a second thickness, the first thickness is less than the second thickness, the power battery also includes a bare battery cell and a negative electrode collector disk connected to the bare battery cell, the negative electrode collector disk is arranged corresponding to the bottom shell and the middle part of the negative electrode collector disk is provided with a protruding portion protruding toward the bottom shell corresponding to the annular welding portion, the protruding portion of the negative electrode collector disk is fitted with the annular welding portion of the bottom shell, and the protruding portion of the negative electrode collector disk is connected to the annular welding portion of the bottom shell by laser penetration welding.

[0005] Preferably, there are at least two annular welding portions, and at least two of the annular welding portions are concentrically arranged.

[0006] Preferably, at least two of the annular welding portions are connected to the protruding portion by laser penetration welding.

[0007] Preferably, the ring width of the annular welding portion is greater than or equal to 0.8 mm and less than or equal to 1.2 mm.

[0008] Preferably, the difference between the second thickness and the first thickness is greater than or equal to 0.1 mm and less than or equal to 0.3 mm.

[0009] Preferably, there are two annular welding parts, and the outer annular welding part located on the outside has an outer ring diameter greater than or equal to 3 mm and less than or equal to 7 mm.

[0010] Preferably, the annular welding portion is integrally stamped or stretched.

[0011] Preferably, the distance between the inner surface of the annular welding portion and the inner surface of the bottom shell is greater than or equal to 0.2 mm and less than or equal to 0.6 mm.

[0012] Preferably, the bottom shell is a steel shell or an aluminum shell.

[0013] The utility model also provides a power battery, comprising a bottom shell, a bare battery cell and a negative electrode current collector plate connected to the bare battery cell, wherein the bottom shell and the negative electrode current collector plate are connected by the welding structure of the power battery bottom shell.

[0014] Compared with the prior art, the utility model provides at least one annular welding portion in the middle of the bottom shell and a raised protrusion on the negative electrode current collecting disk. During assembly, the raised portion in the middle of the negative electrode current collecting disk preferentially contacts and fits with the annular welding portion, thereby avoiding the existence of a gap at the welding position. When laser penetration welding is implemented, better consistency of penetration depth and effective flow area can be achieved. In addition, the thickness of the annular welding portion is thinned, that is, the thickness at the laser penetration welding position is thinned, and a relatively small power laser can be used for welding, which can effectively reduce the power of laser penetration welding, thereby avoiding the risk of possible damage to the bare battery cell due to unstable high-power laser energy, and ultimately improving the yield rate of penetration welding of the bottom shell of the power battery and the consistency of electrical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a structural diagram of a power battery according to an embodiment of the utility model.

[0016] Figure 2 This is a structural diagram of a current collecting plate in a power battery according to an embodiment of the utility model.

[0017] Figure 3 This is a structural diagram of the bottom shell of the power battery in an embodiment of the utility model.

[0018] Figure 4 for Figure 3 Enlarged view of point A in the middle.

[0019] Figure 5 This is a cross-sectional structural diagram of a power battery according to an embodiment of the utility model.

[0020] Figure 6 It is a cross-sectional structural diagram of the outer shell of the power battery in the embodiment of the utility model.

[0021] Figure 7 This is a structural diagram of another bottom shell in a power battery according to an embodiment of the utility model. DETAILED DESCRIPTION

[0022] In order to explain the technical content, structural features and effects achieved by the present invention in detail, the following is a detailed description in conjunction with the implementation modes and the accompanying drawings.

[0023] like Figures 1 to 7 As shown, an embodiment of the utility model provides a welding structure of a bottom shell of a power battery, wherein at least one annular welding portion 21 protruding toward the inner side of the power battery 100 is provided in the middle portion of the bottom shell 2, the annular welding portion 21 has a first thickness, and other areas on the bottom shell 2 except the annular welding portion 21 have a second thickness, and the first thickness is less than the second thickness. The power battery 100 also includes a bare battery cell 4 and a negative electrode collector disk 3 connected to the bare battery cell 4, the negative electrode collector disk 3 is arranged corresponding to the bottom shell 2 and a protrusion 31 protruding toward the bottom shell 2 is provided in the middle portion of the negative electrode collector disk 3 corresponding to the annular welding portion 21, the protrusion 31 of the negative electrode collector disk 3 is in contact with the annular welding portion 21 of the bottom shell 2, and the protrusion 31 of the negative electrode collector disk 3 is connected to the annular welding portion 21 of the bottom shell 2 by laser penetration welding.

[0024] Specifically, the power battery 100 is a cylindrical power battery 100, including an outer shell 10 and a bare battery cell 4 arranged in the outer shell 10, the outer shell 10 includes a cylindrical shell 1 and a bottom shell 2 arranged at the bottom of the cylindrical shell 1, the cylindrical shell 1 and the bottom shell 2 can be integrally formed or separately formed, the negative electrode collector 3 is arranged at the lower part of the bare battery cell 4 and is arranged opposite to the bottom shell 2 to be welded to each other, the negative electrode collector 3 includes a raised portion 31 located in the middle, three recessed portions 32 evenly distributed around the raised portion 31, and a seepage hole 33, the recessed portion 32 is used to be welded to the bare battery cell 4, and the annular welding portion 21 can be thinned by a mold during the molding process so that the first thickness is less than the second thickness.

[0025] In the embodiment of the utility model, by providing at least one annular welding portion 21 in the middle of the bottom shell 2 and providing a raised protrusion 31 on the negative electrode current collecting disk 3, during assembly, the raised portion 31 in the middle of the negative electrode current collecting disk 3 is preferentially contacted and fitted with the annular welding portion 21, so that the existence of a gap at the welding position can be avoided, and when laser penetration welding is implemented, better consistency of penetration depth and effective flow area can be achieved; in addition, the thickness of the annular welding portion 21 is thinned, that is, the thickness at the position of laser penetration welding is thinned, and a relatively small power laser can be used for welding, which can effectively reduce the power of laser penetration welding, so as to avoid the risk of possible damage to the bare battery cell 4 due to unstable high-power laser energy, and ultimately the penetration welding yield and electrical performance consistency of the bottom shell 2 of the power battery 100 are improved.

[0026] In the embodiment of the utility model, there are at least two annular welding parts 21, and at least two annular welding parts 21 are concentrically arranged. Specifically, in actual use, the welding effect can be improved by increasing the number of annular welding parts 21, such as Figures 1 to 6 As shown, there are two annular welding portions 21, namely a first annular welding portion 211 and a second annular welding portion 212. The first annular welding portion 211 and the second annular welding portion 212 are concentrically arranged and spaced apart, and the second annular welding portion 212 is arranged outside the first annular welding portion 211. Of course, the specific number of the annular welding portions 21 is not limited. For example, Figure 7 As shown, the number of the annular welding portion 21 may also be one, that is, only one third annular welding portion 213 is included. The number of the annular welding portions 21 may be adjusted and selected according to actual needs as long as the welding requirements can be met.

[0027] In the embodiment of the utility model, at least two annular welding parts 21 are connected to the raised part 31 by laser penetration welding. Specifically, at least two annular welding parts 21 are in contact with and fit to the raised part 31, thereby increasing the effect of the welding connection.

[0028] In the embodiment of the present invention, the width of the annular welding portion 21 is greater than or equal to 0.8 mm and less than or equal to 1.2 mm. Figure 6 As shown, the ring width W of the annular welding portion 21 is greater than or equal to 0.8 mm and less than or equal to 1.2 mm. This parameter is set on the basis of ensuring the laser welding space, and the thinning process is easier to implement, and the setting is ingenious.

[0029] In the embodiment of the present invention, the difference between the second thickness and the first thickness is greater than or equal to 0.1 mm and less than or equal to 0.3 mm. Figure 6As shown, the annular welding portion 21 is thinned so that the first thickness h of the annular welding portion 21 is smaller than the second thickness H of other areas of the bottom shell 2, and the difference between the second thickness H and the first thickness h is greater than or equal to 0.1 mm and less than or equal to 0.3 mm. That is, after thinning to a very small thickness, a laser with a relatively small power can be used for welding, and the bare battery cell 4 is not easily damaged. The design is very clever.

[0030] In the embodiment of the utility model, there are two annular welding parts 21, and the outer diameter of the annular welding part 21 located on the outside is greater than or equal to 3 mm and less than or equal to 7 mm. Figure 3 to Figure 4 As shown, the second annular welding portion 212 has a smaller inner diameter and a larger outer diameter D, and the larger outer diameter D is greater than or equal to 3 mm and less than or equal to 7 mm.

[0031] In the embodiment of the utility model, the annular welding part 21 is integrally stamped or integrally stretched. Specifically, the annular welding part 21 can be integrally stamped on the bottom shell 2, or the annular welding part 21 can be integrally stretched on the bottom shell 2, which is simple in process, easy to implement and has good performance.

[0032] In the embodiment of the utility model, Figure 6 As shown, the distance L between the inner surface of the annular welding portion 21 and the inner surface of the bottom shell 2 is greater than or equal to 0.2 mm and less than or equal to 0.6 mm.

[0033] In the embodiment of the utility model, the bottom shell 2 is a steel shell or an aluminum shell.

[0034] The assembly method of the embodiment of the present invention is as follows: first, the recessed portion 32 of the negative electrode current collector 3 is adapted to one end of the copper foil full-pole ear of the bare battery cell 4, and laser welding is used to fix it; then the bare battery cell 4 is put into the shell so that the negative electrode current collector 3 faces the bottom shell 2, and the bare battery cell 4 is supported by a clamp, and the raised portion 31 in the middle of the negative electrode current collector 3 is fitted with the annular welding portion 21 of the bottom shell 2, and laser penetration welding is performed from the outside of the bottom shell 2 to fix it.

[0035] The utility model also provides a power battery 100, comprising a bottom shell 2, a bare battery cell 4 and a negative electrode collector plate 3 connected to the bare battery cell 4, wherein the bottom shell 2 and the negative electrode collector plate 3 are connected using the welding structure of the bottom shell 2 of the power battery 100.

[0036] In the power battery 100 of the embodiment of the utility model, by setting at least one annular welding portion 21 in the middle of the bottom shell 2 and setting a raised protrusion 31 on the negative current collecting disc 3, during assembly, the protrusion 31 in the middle of the negative current collecting disc 3 is preferentially contacted and fitted with the annular welding portion 21, which can avoid the existence of a gap at the welding position, and when laser penetration welding is implemented, better consistency of penetration depth and effective flow area can be achieved; in addition, the thickness of the annular welding portion 21 is thinned, that is, the thickness at the position of laser penetration welding is thinned, and a relatively small power laser can be used for welding, which can effectively reduce the power of laser penetration welding, so as to avoid the risk of possible damage to the bare battery cell 4 due to unstable high-power laser energy, and ultimately the penetration welding yield and electrical performance consistency of the bottom shell 2 of the power battery 100 are improved.

[0037] The above disclosure is only a preferred example of the present invention, and certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention still fall within the scope covered by the present invention.

Claims

1. A welding structure of a power battery bottom shell, characterized in that: The middle part of the bottom shell is provided with at least one annular welding portion protruding toward the inner side of the power battery, the annular welding portion has a first thickness, and other areas on the bottom shell except the annular welding portion have a second thickness, and the first thickness is less than the second thickness. The power battery also includes a bare battery cell and a negative electrode collector disk connected to the bare battery cell, the negative electrode collector disk is arranged corresponding to the bottom shell, and the middle part of the negative electrode collector disk is provided with a protrusion protruding toward the bottom shell corresponding to the annular welding portion, the protrusion of the negative electrode collector disk is in contact with the annular welding portion of the bottom shell, and the protrusion of the negative electrode collector disk is connected to the annular welding portion of the bottom shell by laser penetration welding.

2. The welding structure of the power battery bottom shell according to claim 1, characterized in that: There are at least two annular welding parts, and at least two of the annular welding parts are concentrically arranged.

3. The welding structure of the power battery bottom shell according to claim 2, characterized in that: At least two of the annular welding portions are connected to the protruding portion by laser penetration welding.

4. The welding structure of the power battery bottom shell according to claim 1, characterized in that: The ring width of the annular welding portion is greater than or equal to 0.8 mm and less than or equal to 1.2 mm.

5. The welding structure of the power battery bottom shell according to claim 1, characterized in that: A difference between the second thickness and the first thickness is greater than or equal to 0.1 mm and less than or equal to 0.3 mm.

6. The welding structure of the power battery bottom shell according to claim 1, characterized in that: There are two annular welding parts, and the outer ring diameter of the annular welding part located on the outside is greater than or equal to 3 mm and less than or equal to 7 mm.

7. The welding structure of the power battery bottom shell according to claim 1, characterized in that: The annular welding portion is integrally stamped or stretched.

8. The welding structure of the power battery bottom shell according to claim 1, characterized in that: The distance between the inner surface of the annular welding portion and the inner surface of the bottom shell is greater than or equal to 0.2 mm and less than or equal to 0.6 mm.

9. The welding structure of the power battery bottom shell according to claim 1, characterized in that: The bottom shell is a steel shell or an aluminum shell.

10. A power battery, characterized in that: It comprises a bottom shell, a bare battery cell and a negative electrode current collector plate connected to the bare battery cell, wherein the bottom shell and the negative electrode current collector plate are connected by adopting the welding structure of the power battery bottom shell as claimed in any one of claims 1 to 9.

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