Battery cell, battery pack and electric equipment

Abstract

The utility model discloses a battery cell, a battery pack and electric equipment. The battery cell comprises a shell, a cover body, a pole, a connecting piece and an electrode assembly, the electrode assembly is arranged in the shell, the cover body covers the shell in a sealing mode, the pole penetrates through the cover body, the connecting piece comprises a first connecting part and a second connecting part, the first connecting part is connected with the electrode assembly, the second connecting part is connected with the pole, a welding area is arranged on the side, away from the pole, of the second connecting part, and the welding area is provided with a plurality of first concave structures arranged at intervals; the first sunken structure is sunken inwards from the surface of the connecting piece to form a first side wall and a bottom wall, and the included angle between the first side wall and the bottom wall is A; the width direction of the connecting piece is the first direction, the maximum size of the bottom wall in the first direction is L0, the width of the second connecting part is D, and A is larger than 90 degrees and smaller than or equal to 135 degrees, L0 is larger than or equal to 0.1 mm and smaller than or equal to 0.05 * D, and D is larger than or equal to 20 mm and smaller than or equal to 100 mm. Therefore, a light trapping effect can be formed when laser is irradiated into the first sunken structure, and the welding effect on the connecting piece and the pole is improved.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to a battery cell, a battery pack, and an electrical device. Background Technology

[0002] Power batteries are characterized by being pollution-free, having high energy density, and long lifespan, and have been widely used in electric vehicles and energy storage. As power battery technology continues to develop, higher requirements are being placed on their manufacturing processes to reduce manufacturing costs and improve safety.

[0003] In power batteries, connecting tabs are typically used to make electrical connections between the tabs and terminals of the battery cell. In related technologies, laser welding is generally used to fix the connection between the connecting tabs and terminals. However, since the surface of the connecting tabs is relatively smooth, reflection is easily generated during the laser welding process, causing defects such as incomplete welding, which affects the connection performance between the connecting tabs and terminals. Utility Model Content

[0004] This application aims to provide a battery cell, battery pack, and electrical device that can solve the problem that defects such as incomplete welding are prone to occur when welding the connecting piece and the terminal in existing batteries, which affects the connection performance between the connecting piece and the terminal.

[0005] To solve the above-mentioned technical problems, this application is implemented as follows:

[0006] In a first aspect, embodiments of this application provide a battery cell, comprising: a housing, a cover, a terminal post, a connecting piece, and an electrode assembly;

[0007] The housing has a receiving cavity, the electrode assembly is disposed in the receiving cavity, the cover is connected to the housing to seal the receiving cavity, the electrode post passes through the cover, the connecting piece is disposed in the receiving cavity, the connecting piece includes a first connecting part and a second connecting part that are connected to each other, the first connecting part is connected to the electrode assembly, the second connecting part is connected to the electrode post, and the second connecting part has a welding area on the side away from the electrode post, and the welding area has a plurality of spaced first recessed structures.

[0008] The first recessed structure is recessed from the surface of the connecting piece inward to form a first sidewall and a bottom wall, and the included angle between the first sidewall and the bottom wall is A; the width direction of the connecting piece is a first direction, and a plurality of the recessed structures are arranged at intervals along the first direction, the maximum dimension of the bottom wall along the first direction is L0, and the width of the second connecting part is D, satisfying: 90°<A≤135°, 0.1mm≤L0≤0.05*D, 20mm≤D≤100mm.

[0009] Optionally, the maximum dimension L0 of the bottom wall along the first direction satisfies: 0.1mm≤L0≤1mm.

[0010] Optionally, along the first direction, the distance between two adjacent first recessed structures is L1, satisfying: 0.1mm≤L1≤0.05*D.

[0011] Optionally, the bottom wall is circular or square.

[0012] Optionally, a plurality of the first recessed structures are arranged in an array, and the spacing between two adjacent first recessed structures is equal.

[0013] Optionally, the connecting piece has a second direction intersecting the first direction, and the welding area is further provided with a plurality of second recessed structures, the plurality of second recessed structures including a plurality of first strip grooves, the first strip grooves extending along the first direction and communicating with at least a portion of the first recessed structures, and the plurality of first strip grooves being arranged at intervals along the second direction.

[0014] Optionally, the plurality of second recessed structures further include a plurality of second strip grooves, the second strip grooves extending along the second direction and communicating with at least a portion of the first recessed structure, and the plurality of second strip grooves being arranged at intervals along the first direction.

[0015] Optionally, along the thickness direction of the connecting piece, the orthographic projection of the pole is located within the orthographic projection of the welding area.

[0016] Secondly, embodiments of this application propose a battery pack including the battery cells described in the first aspect.

[0017] Thirdly, embodiments of this application propose an electrical device that includes the battery cell described in the first aspect, or the battery pack described in the second aspect.

[0018] In this application, the connecting piece is connected to the electrode post via a second connecting portion. The second connecting portion has a welding area for welding away from the electrode post, and multiple first recessed structures are provided within the welding area. This allows the laser to irradiate the first recessed structures and create a light-trapping effect when welding the connecting piece and the electrode post using a laser, thereby improving the welding effect. Furthermore, by setting the bottom wall size to be less than 0.05 times the width of the second connecting portion, as many first recessed structures as possible can be arranged within a given width of the second connecting portion, thus improving the overall welding effect of the welding area. This also avoids the bottom wall size being too large, causing the incident laser to directly irradiate the bottom wall and reflect, thus preventing the light-trapping effect from forming. Simultaneously, by setting the bottom wall size to be greater than or equal to 0.1 mm, it avoids the bottom wall size being too small, preventing the laser from being unable to enter the first recessed structures. In addition, by limiting the angle range between the first sidewall and the bottom wall, the number of reflections of the incident laser in the first recessed structure is controlled. On the one hand, this ensures that the incident laser can generate more than two reflections in the first recessed structure, increasing the laser energy input to improve the laser welding effect. On the other hand, it also avoids that the incident laser is reflected too many times in the first recessed structure, resulting in excessive laser input energy and causing thermal effects on the battery cell.

[0019] Additional aspects and advantages of this application 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 this application. Attached Figure Description

[0020] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0021] Figure 1 This is a schematic diagram of a battery cell according to an embodiment of this application;

[0022] Figure 2 This is a schematic diagram of a connecting piece according to an embodiment of this application;

[0023] Figure 3 This is a schematic diagram of the arrangement of the first recessed structure in the welding area of ​​the connecting piece according to an embodiment of this application;

[0024] Figure 4 This is a schematic diagram of a first recessed structure according to an embodiment of this application;

[0025] Figure 5 This is a schematic diagram of another first recessed structure according to an embodiment of this application;

[0026] Figure 6 This is a schematic diagram of the arrangement of the second recessed structure in the welding area of ​​the connecting piece according to an embodiment of this application;

[0027] Figure 7 This is one of the schematic diagrams illustrating the light-trapping effect of the first recessed structure in the connecting piece according to an embodiment of this application.

[0028] Figure label:

[0029] 1: Connecting piece; 1a: First connecting part; 1b: Second connecting part; 10: Welding area; 11: First recessed structure; 111: First sidewall; 112: Bottom wall; A: Included angle; 12: Second recessed structure; 121: First strip groove; 122: Second strip groove; 2: Cover; 3: Electrode post; 4: Electrode assembly; 5: Housing; X: First direction; Y: Second direction; Z: Third direction. Detailed Implementation

[0030] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated 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 application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0031] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0032] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application.

[0033] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0034] The following description, in conjunction with the accompanying drawings, details the battery cells, battery packs, and electrical devices provided in the embodiments of this application through specific examples and application scenarios.

[0035] like Figures 1 to 3 As shown, a battery cell according to some embodiments of this application includes: a housing 5, a cover 2, an electrode post 3, a connecting piece 1, and an electrode assembly 4; the housing 5 has a receiving cavity, the electrode assembly 4 is disposed in the receiving cavity, the cover 2 is connected to the housing 5 to cover the receiving cavity, the electrode post 3 passes through the cover 2, the connecting piece 1 is disposed in the receiving cavity, the connecting piece 1 includes a first connecting part 1a and a second connecting part 1b that are connected to each other, the first connecting part 1a is connected to the electrode assembly 4, the second connecting part 1b is connected to the electrode post 3, and a welding area 10 is provided on the side of the second connecting part 1b away from the electrode post 3, and a plurality of first recessed structures 11 are arranged at intervals in the welding area 10.

[0036] The first recessed structure 11 is recessed from the surface of the connecting piece 1 inward to form a first sidewall 111 and a bottom wall 112, and the included angle between the first sidewall 111 and the bottom wall 112 is A (e.g., ...). Figure 7 (as shown); the width direction of the connecting piece 1 is the first direction X, and multiple first recessed structures 11 are arranged at intervals along the first direction X; the maximum dimension of the bottom wall 112 along the first direction X is L0, and the width of the second connecting part 1b is D, satisfying: 90°<A≤135°, 0.1mm≤L0≤0.05*D, 20mm≤D≤100mm.

[0037] In the embodiments of this application, the connecting piece 1 is connected to the pole post 3 via a second connecting portion 1b. The second connecting portion 1b is provided with a welding area 10 for welding away from the pole post 3, and a plurality of first recessed structures 11 are provided in the welding area 10. The first sidewall 111 and the bottom wall 112 of the first recessed structure 11 form an obtuse angle so that when the connecting piece 1 and the pole post 3 are welded by laser, the laser irradiates the welding area of ​​the connecting piece 1, and the laser is reflected multiple times in the first recessed structure to form a light trapping effect. This can reduce the reflection of the laser on the surface of the connecting piece 1, thereby improving the welding effect of the connecting piece 1 and the pole post 3. Furthermore, by setting the size L0 of the bottom wall 112 to be less than 0.05 times the width D of the second connecting portion 1b, so that as many first recessed structures 11 as possible can be arranged when the width of the second connecting portion 1b is fixed, thereby improving the overall welding effect of the welding area 10, and also avoiding the bottom wall 112 being too large, which would cause the incident laser to directly irradiate the bottom wall 112 and cause reflection, thus failing to form a light trapping effect. Meanwhile, by setting the size of the bottom wall 112 to be greater than or equal to 0.1 mm, the size of the bottom wall 112 is avoided from being too small, which would prevent the laser from entering the first recessed structure 11.

[0038] In addition, such as Figure 7 As shown, by limiting the angle range of the angle A between the first sidewall 111 and the bottom wall 112, the number of reflections of the incident laser in the first recessed structure 11 is controlled. On the one hand, this ensures that the incident laser can generate more than two reflections in the first recessed structure 11, increasing the laser energy input to improve the laser welding effect. On the other hand, it also avoids that the incident laser is reflected too many times in the first recessed structure 11, resulting in excessive laser input energy and causing thermal effects on the battery cell.

[0039] It is understood that the connecting piece 1 in this application has a sheet-like structure. The sheet-like connecting piece 1 has a length, a width, and a thickness, wherein the length is greater than the width, the width is greater than the thickness, and the width direction is set as the first direction X, the length direction as the second direction Y, and the thickness direction as the third direction Z.

[0040] Specifically, the connecting piece 1 includes a first connecting part 1a and a second connecting part 1b that are connected to each other. The first connecting part 1a is connected to the electrode assembly 4, and the second connecting part 1b is connected to the electrode post 3. It should be noted that the first connecting part 1a and the second connecting part 1b can be arranged along the first direction X or along the second direction Y, and there is no limitation on this.

[0041] Furthermore, a welding area 10 is provided on the side of the second connecting portion 1b of the connecting piece 1 away from the pole post 3, so that during the cell assembly operation, the welding area 10 of the second connecting portion 1b can be irradiated by a laser to weld and fix the second connecting portion 1b to the pole post 3. A plurality of first recessed structures 11 are provided in the welding area 10 at intervals. The first recessed structures 11 extend from the surface of the connecting piece 1 away from the pole post 3 to the interior recess of the connecting piece 1.

[0042] In the battery cell manufacturing process, laser welding is typically used to weld and fix the connecting piece 1 and the electrode post 3. If the surface of the connecting piece 1 is relatively smooth, some of the laser light will be reflected on the surface of the connecting piece 1 during laser welding, resulting in energy attenuation of the laser light acting on the connecting piece 1, which is detrimental to the welding of the connecting piece 1 and the electrode post 3. To address this, this application provides multiple first recessed structures 11 within the welding area 10 of the electrode. When the laser irradiates the welding area 10 of the connecting piece 1, the multiple first recessed structures 11 can create a light trapping effect. The incident laser light is reflected multiple times by the sidewalls of the first recessed structures 11, which increases the energy input of the laser light, thereby improving the welding effect between the connecting piece 1 and the electrode post 3.

[0043] Furthermore, by setting the maximum dimension L0 of the bottom wall 112 of the first recessed structure 11 along the first direction X to be less than 0.05 times the width D of the second connecting portion 1b, the dimension L0 of the bottom wall 112 is avoided from being too large. If the dimension of the bottom wall 112 of the first recessed structure 11 is too large, the corresponding pit formed by the first recessed structure 11 will be larger, which will cause the incident laser to directly irradiate the bottom wall 112 and be reflected out of the connecting piece 1, failing to form an effective light-trapping effect. Moreover, since the width dimension D of the second connecting portion 1b is limited, if the dimension of a single first recessed structure 11 is too large, it will affect the number and structural layout of the first recessed structures 11 in the welding area 10, which is not conducive to the welding of the connecting piece 1 and the pole post 3.

[0044] Meanwhile, by setting the maximum dimension L0 of the bottom wall 112 of the first recessed structure 11 along the first direction X to be greater than or equal to 0.1 mm, the dimension L0 of the bottom wall 112 is avoided to be too small. If the dimension of the bottom wall 112 of the first recessed structure 11 is too small, on the one hand, the bottom of the first recessed structure 11 will be too sharp, and sharp debris will be easily generated during the processing of the first recessed structure 11, which may lead to the risk of the electrode assembly 4 being punctured. On the other hand, the sharp bottom of the first recessed structure 11 is also easy to be welded through during the welding process, affecting the welding effect.

[0045] In some embodiments, the first recessed structure 11 may have one sidewall or two or more sidewalls. For example, when the bottom wall 112 and the opening of the first recessed structure 11 are both circular or elliptical, the first recessed structure 11 has a curved sidewall, which is the first sidewall 111, and the angle A between the curved sidewall and the plane containing the bottom wall 112 is the angle A. As another example, when the bottom wall 112 and the opening of the first recessed structure 11 are both polygonal, the first recess has multiple planar sidewalls, and at least one of these planar sidewalls is positioned at an angle A with the plane containing the bottom wall 112; this planar sidewall is also the first sidewall 111.

[0046] It should be noted that the first sidewall 111 in this application can be a curved surface or a plane, and the bottom wall 112 is a plane. The angle A between the first sidewall 111 and the bottom wall 112 can be measured by referring to the measurement method of the angle between a curved surface and a plane or the angle between two planes in the related technology, and will not be repeated here.

[0047] In some embodiments, the bottom wall 112 is circular or square. Correspondingly, the first recessed structure 11 is also circular or square at its opening. This allows for a more uniform reflection of the incident laser at different positions on the sidewalls of the first recessed structure 11.

[0048] Specifically, such as Figure 4 As shown, both the bottom wall 112 and the opening of the first recessed structure 11 can be circular, and the cross-sectional area of ​​the first recessed structure 11 gradually decreases from the opening to the bottom wall 112. The line connecting the center of the circle formed by the bottom wall 112 and the circle formed by the opening is parallel to the thickness direction (i.e., the third direction Z) of the connecting piece 1. When the incident laser perpendicularly irradiates the surface of the connecting piece 1, the reflection effect at different positions of the circumferential sidewall of the first recessed structure 11 is the same or similar, thereby improving the welding effect between the connecting piece 1 and the pole post 3.

[0049] Or, as Figure 5 As shown, the bottom wall 112 and opening of the first recessed structure 11 can also be set as squares, and the cross-sectional area of ​​the first recessed structure 11 gradually decreases from the opening to the bottom wall 112. The line connecting the center of the square formed by the bottom wall 112 and the square formed by the opening is parallel to the thickness direction (i.e., the third direction Z) of the connecting piece 1. When the incident laser perpendicularly irradiates the surface of the connecting piece 1 at the corresponding position of the welding area 10, the reflection effect of the four sidewalls of the first recessed structure 11 is the same or similar, thereby improving the welding effect between the connecting piece 1 and the pole post 3. In this embodiment, all four sidewalls of the first recessed structure 11 are the first sidewall 111.

[0050] Furthermore, when the bottom wall 112 of the first recessed structure 11 is square, one side of the two adjacent sides of the square formed by the bottom wall 112 can be parallel to the side of the connecting piece 1 in the width direction and the other side is parallel to the side of the connecting piece 1 in the length direction, thereby facilitating the layout and processing of multiple first recessed structures 11 in the welding area 10.

[0051] Of course, the first recessed structure 11 can also be configured as other structures, as long as it is ensured that at least one side wall of the first recessed structure 11 can form the included angle A with the bottom wall 112 so that the laser irradiation into the first recessed structure 11 can form a light trapping effect. For example, the bottom wall 112 of the first recessed structure 11 can also be elliptical, pentagonal, hexagonal, etc., and is not limited to the structure described in the above embodiments. Those skilled in the art can flexibly set it according to actual needs.

[0052] In some embodiments, such as Figure 2 As shown, the width D of the second connecting part 1b along the first direction X can be set to: 20mm, 30mm, 50mm, 80mm, 100mm, etc. Figure 7 As shown, the included angle A between the first sidewall 111 and the bottom wall 112 can be set to 92°, 100°, 105°, 110°, 115°, 120°, 125°, 130°, 135°, etc.

[0053] It should be noted that the widths of the first connecting part 1a and the second connecting part 1b along the first direction X can be set to be the same or different, and can be flexibly set according to actual needs, without limitation here.

[0054] In other embodiments, such as Figure 3 As shown, the maximum dimension L0 of the bottom wall 112 along the first direction X can be set to 0.1mm≤L0≤5mm, preferably 0.1mm≤L0≤1mm. By setting a reasonable range for the dimension L0 of the bottom wall 112, the first recessed structure 11 can be used to generate multiple reflections of the incident laser to form a light-trapping effect, thereby increasing the laser energy input and improving the welding effect between the connecting piece 1 and the pole post 3. At the same time, it can also avoid the bottom wall 112 being too large, causing the incident laser to directly irradiate the bottom wall 112 and generate reflection, thus failing to form an effective light-trapping effect.

[0055] For example, such as Figure 3 As shown, the maximum dimension L0 of the bottom wall 112 in the first direction X can be set to: 0.1mm, 0.3mm, 0.5mm, 0.8mm, 0.9mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, etc.

[0056] For example, when the bottom wall 112 is circular, the diameter of the circle is the dimension L0; when the bottom wall 112 is square, the side length of the square is the dimension L0; when the bottom wall 112 is in other shapes, the maximum value of multiple dimensions from one side to the other of the bottom wall 112 can be measured along the first direction to be the dimension L0.

[0057] Optionally, such as Figure 3 As shown, along the first direction X, the distance between two adjacent first recessed structures 11 is L1, which satisfies: 0.1mm≤L1≤0.05*D. By setting the distance range between two adjacent first recessed structures 11, the first recessed structures 11 in the welding area 10 are not set too densely, which would affect the structural strength of the connecting piece 1. At the same time, the first recessed structures 11 are also not set too sparsely, which would not achieve an effective light trapping effect.

[0058] For example, the spacing L1 between two adjacent first recessed structures 11 can be set to: 0.1mm, 0.3mm, 0.5mm, 0.8mm, 0.9mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, etc.

[0059] Optionally, such as Figure 3 As shown, multiple first recessed structures 11 are arranged in an array, and the spacing between two adjacent first recessed structures 11 is equal.

[0060] In this embodiment of the application, by setting multiple first recessed structures 11 in an array and making the distance between two adjacent first recessed structures 11 equal, it is ensured that the multiple first recessed structures 11 are evenly arranged in the welding area 10, thereby improving the uniformity of welding between the welding area 10 and the pole post 3 at different positions, thereby improving the connection strength between the connecting piece 1 and the pole post 3.

[0061] For example, the array arrangement includes, but is not limited to, rectangular array, circular array, hexagonal array, rhomboid array, etc. The array arrangement structure of the multiple first recessed structures 11 can be flexibly set according to the actual situation, and is not limited here.

[0062] It should be noted that the distance between two adjacent first recessed structures 11 includes the spacing between two adjacent first recessed structures 11 along the first direction X, and / or the spacing between two adjacent first recessed structures 11 along the second direction Y.

[0063] Optionally, such as Figure 6As shown, the connecting piece 1 has a second direction Y intersecting the first direction X. The welding area 10 is also provided with a plurality of second recessed structures 12. The plurality of second recessed structures 12 include a plurality of first strip grooves 121. The first strip grooves 121 extend along the first direction X and communicate with at least a portion of the first recessed structures 11. The plurality of first strip grooves 121 are arranged at intervals along the second direction Y.

[0064] In this embodiment of the application, a plurality of first strip grooves 121 are provided in the welding area 10. The first strip grooves 121 extend along the first direction X. The first strip grooves 121 have two side walls that are arranged opposite to each other along the second direction Y. The two side walls of the first strip grooves 121 can be set to form an angle A with the bottom wall so that when the incident laser irradiates the first strip grooves 121, a light trapping effect can also be formed. At the same time, the strip groove structure also facilitates actual processing.

[0065] Optionally, such as Figure 6 As shown, the plurality of second recessed structures 12 further include a plurality of second strip grooves 122, the second strip grooves 122 extending along the second direction Y and communicating with at least a portion of the first recessed structure 11, and the plurality of second strip grooves 122 being arranged at intervals along the first direction X.

[0066] In this embodiment, a plurality of second strip grooves 122 are provided in the welding area 10 of the connecting piece 1. The second strip grooves 122 extend along the second direction Y. The second strip grooves 122 have two side walls that are arranged opposite to each other along the first direction X. The two side walls of the second strip grooves 122 can be set to form an angle A with the bottom wall so that when the incident laser irradiates into the second strip grooves 122, a light trapping effect can also be formed. At the same time, the strip groove structure also facilitates actual processing.

[0067] It is understandable that, such as Figure 6 As shown, a plurality of first strip grooves 121 and a plurality of second strip grooves 122 are arranged in a crisscross pattern, and a first recessed structure 11 is formed at the intersection of the first strip grooves 121 and the second strip grooves 122.

[0068] In some embodiments, the first direction X and the second direction Y can be set to be perpendicular to each other, that is, the extending direction of the first strip groove 121 is perpendicular to the extending direction of the second groove. Alternatively, the angle between the first direction X and the second direction Y can be set to an acute or obtuse angle. For example, the angle between the first direction X and the second direction Y can be set to 60°, 75°, 80°, 100°, 135°, etc. In this case, the extending direction of the first strip groove 121 and the extending direction of the second groove form an acute or obtuse angle. It should be noted that the specific extending directions of the first strip groove 121 and the second groove can be flexibly set according to actual needs and are not limited here.

[0069] Optionally, such as Figure 1 As shown, along the thickness direction of the connecting piece 1 (i.e., the third direction Z), the orthographic projection of the pole post 3 is located within the orthographic projection of the welding area 10.

[0070] In this embodiment, the orthographic projection of the pole post 3 is positioned within the orthographic projection of the welding area 10 along the third direction Z, to ensure that the second connecting part 1b of the connecting piece 1 can form a stable connection by performing welding operations within the welding area 10. Furthermore, by providing multiple first recessed structures 11 within the welding area 10, the welding effect between the pole post 3 and the connecting piece 1 can be improved, ensuring the connection strength between the pole post 3 and the connecting piece 1.

[0071] In some embodiments, connecting pieces 1 with different structural dimensions are welded to pole posts 3. The effective penetration depth of the weld structure is measured to evaluate the influence of the structural parameters of connecting pieces 1 on the welding effect. A total of 5 sets of tests are set up, each set of tests includes 6 test samples with the same structure. The only differences between the 5 sets of test samples are the width D of the second connecting part 1b of connecting piece 1, the dimension L0 of the bottom wall 112, the included angle A, and the distance L1 between two adjacent first recessed structures 11. All other structures and welding processes are the same.

[0072] Specifically, the method for measuring the effective penetration depth includes: welding the second connecting part 1b of the connecting piece 1 to the pole post 3 to form a welded structure; cutting the welded position of the welded structure along the thickness direction of the connecting piece 1; using a two-dimensional measuring instrument to test the effective penetration depth; taking the maximum penetration depth of a single test sample as the effective penetration depth; and calculating the average of the effective penetration depths obtained from the tests of 6 samples in each test group as the final test value for that group of tests. It can be understood that the maximum penetration depth refers to the vertical distance between the deepest point of the molten portion of the connecting piece 1 at the weld and the surface of the connecting piece 1. Specific test results are shown in Table 1 below:

[0073] Table 1

[0074]

[0075] As can be seen from the experimental data in Table 1 above, by controlling the angle A between the first sidewall 111 and the bottom wall 112 of the first recessed structure 11 to be greater than 90° and less than or equal to 135°, the effective penetration depth of the connecting piece 1 at the welding position can be significantly improved, thereby helping to improve the welding effect between the connecting piece 1 and the pole post 3. This is because when the angle A is 90°, when the laser is perpendicularly irradiated onto the surface of the connecting piece 1, the incident direction of the laser is parallel to the first sidewall 111, and the first sidewall 111 cannot reflect the incident laser, thus failing to form a light-trapping effect. However, if the angle A is greater than 135°, the incident laser will be reflected too many times within the first recessed structure 11, which is also detrimental to the welding of the connecting piece 1 and the pole post 3, and will instead reduce the effective penetration depth.

[0076] Furthermore, comparing the experimental data of Example 4 and Comparative Example 2, it can be seen that when the bottom wall 112 size L0 of the first recessed structure 11 is too small, since the minimum diameter of the laser spot is fixed, the laser cannot enter the first recessed structure 11 if the first recessed structure 11 is too small, and thus cannot form an effective light trapping effect, which will also affect the welding effect between the connecting piece 1 and the pole post 3.

[0077] Optionally, embodiments of this application also provide a battery pack, including the battery cells described in the above embodiments.

[0078] In the embodiments of this application, the connecting piece 1 is connected to the pole post 3 via a second connecting portion 1b. The second connecting portion 1b is provided with a welding area 10 for welding away from the pole post 3, and a plurality of first recessed structures 11 are provided in the welding area 10. The first sidewall 111 and the bottom wall 112 of the first recessed structure 11 form an obtuse angle so that when the connecting piece 1 and the pole post 3 are welded by laser, the laser irradiates the welding area of ​​the connecting piece 1, and the laser is reflected multiple times in the first recessed structure to form a light trapping effect. This can reduce the reflection of the laser on the surface of the connecting piece 1, thereby improving the welding effect of the connecting piece 1 and the pole post 3. Furthermore, by setting the size L0 of the bottom wall 112 to be less than 0.05 times the width D of the second connecting portion 1b, so that as many first recessed structures 11 as possible can be arranged when the width of the second connecting portion 1b is fixed, thereby improving the overall welding effect of the welding area 10, and also avoiding the bottom wall 112 being too large, which would cause the incident laser to directly irradiate the bottom wall 112 and cause reflection, thus failing to form a light trapping effect. Meanwhile, by setting the size of the bottom wall 112 to be greater than or equal to 0.1 mm, the size of the bottom wall 112 is avoided from being too small, which would prevent the laser from entering the first recessed structure 11.

[0079] Furthermore, by limiting the angle range of the angle A between the first sidewall 111 and the bottom wall 112, the number of reflections of the incident laser within the first recessed structure 11 is controlled. On the one hand, this ensures that the incident laser can generate more than two reflections within the first recessed structure 11, increasing the laser energy input to improve the laser welding effect. On the other hand, it also avoids that the incident laser is reflected too many times within the first recessed structure 11, resulting in excessive laser input energy and causing thermal effects on the battery cell.

[0080] Optionally, embodiments of this application also provide an electrical device, including the battery cell in the above embodiments, or including the battery pack in the above embodiments.

[0081] In the embodiments of this application, the connecting piece 1 is connected to the pole post 3 via a second connecting portion 1b. The second connecting portion 1b is provided with a welding area 10 for welding away from the pole post 3, and a plurality of first recessed structures 11 are provided in the welding area 10. The first sidewall 111 and the bottom wall 112 of the first recessed structure 11 form an obtuse angle so that when the connecting piece 1 and the pole post 3 are welded by laser, the laser irradiates the welding area of ​​the connecting piece 1, and the laser is reflected multiple times in the first recessed structure to form a light trapping effect. This can reduce the reflection of the laser on the surface of the connecting piece 1, thereby improving the welding effect of the connecting piece 1 and the pole post 3. Furthermore, by setting the size L0 of the bottom wall 112 to be less than 0.05 times the width D of the second connecting portion 1b, so that as many first recessed structures 11 as possible can be arranged when the width of the second connecting portion 1b is fixed, thereby improving the overall welding effect of the welding area 10, and also avoiding the bottom wall 112 being too large, which would cause the incident laser to directly irradiate the bottom wall 112 and cause reflection, thus failing to form a light trapping effect. Meanwhile, by setting the size of the bottom wall 112 to be greater than or equal to 0.1 mm, the size of the bottom wall 112 is avoided from being too small, which would prevent the laser from entering the first recessed structure 11.

[0082] Furthermore, by limiting the angle range of the angle A between the first sidewall 111 and the bottom wall 112, the number of reflections of the incident laser within the first recessed structure 11 is controlled. On the one hand, this ensures that the incident laser can generate more than two reflections within the first recessed structure 11, increasing the laser energy input to improve the laser welding effect. On the other hand, it also avoids that the incident laser is reflected too many times within the first recessed structure 11, resulting in excessive laser input energy and causing thermal effects on the battery cell.

[0083] In some embodiments, electrical devices may include laptops, pen-based computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, bicycles, ships, spacecraft, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, and lithium-ion capacitors, etc.

[0084] Specifically, the vehicle can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc.

[0085] 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 this application. 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.

[0086] Although embodiments of this application 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 this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A battery cell, characterized in that, include: The shell (5), cover (2), pole post (3), connecting piece (1) and electrode assembly (4); The housing (5) has a receiving cavity, the electrode assembly (4) is disposed in the receiving cavity, the cover (2) is connected to the housing (5) to cover the receiving cavity, the pole (3) passes through the cover (2), the connecting piece (1) is disposed in the receiving cavity, the connecting piece (1) includes a first connecting part (1a) and a second connecting part (1b) connected to each other, the first connecting part is connected to the electrode assembly (4), the second connecting part (1b) is connected to the pole (3), the second connecting part (1b) has a welding area (10) on the side away from the pole (3), the welding area (10) has a plurality of spaced first recessed structures (11); The first recessed structure (11) is recessed from the surface of the connecting piece (1) to form a first sidewall (111) and a bottom wall (112), and the included angle between the first sidewall (111) and the bottom wall (112) is A; the width direction of the connecting piece (1) is the first direction (X), and a plurality of the recessed structures are arranged at intervals along the first direction (X). The maximum dimension of the bottom wall (112) along the first direction (X) is L0, and the width of the second connecting part (1b) is D, satisfying: 90°<A≤135°, 0.1mm≤L0≤0.05*D, 20mm≤D≤100mm.

2. The battery cell according to claim 1, characterized in that, The maximum dimension L0 of the bottom wall (112) along the first direction (X) satisfies: 0.1mm≤L0≤1mm.

3. The battery cell according to claim 1, characterized in that, Along the first direction (X), the distance between two adjacent first recessed structures (11) is L1, which satisfies: 0.1mm≤L1≤0.05*D.

4. The battery cell according to claim 1, characterized in that, The bottom wall (112) is circular or square.

5. The battery cell according to claim 1, characterized in that, Multiple first recessed structures (11) are arranged in an array, and the spacing between two adjacent first recessed structures (11) is equal.

6. The battery cell according to any one of claims 1-5, characterized in that, The connecting piece (1) has a second direction (Y) intersecting the first direction (X). The welding area (10) is further provided with a plurality of second recessed structures (12). The plurality of second recessed structures (12) include a plurality of first strip grooves (121). The first strip grooves (121) extend along the first direction (X) and communicate with at least a portion of the first recessed structures (11). The plurality of first strip grooves (121) are arranged at intervals along the second direction (Y).

7. The battery cell according to claim 6, characterized in that, The plurality of second recessed structures (12) further include a plurality of second strip grooves (122), the second strip grooves (122) extending along the second direction (Y) and communicating with at least a portion of the first recessed structure (11), and the plurality of second strip grooves (122) being arranged at intervals along the first direction (X).

8. The battery cell according to claim 1, characterized in that, Along the thickness direction of the connecting piece (1), the orthographic projection of the pole post (3) is located within the orthographic projection of the welding area (10).

9. A battery pack, characterized in that, Including the battery cell as described in any one of claims 1-8.

10. An electrical appliance, characterized in that, It includes the battery cell as described in any one of claims 1-8, or the battery pack as described in claim 9.

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