Cylindrical battery, battery pack and electronic device

Abstract

The utility model provides a cylindrical battery, a battery pack and an electronic device, the cylindrical battery comprises a shell, an electrode assembly and a current collecting component, the shell comprises a side wall, and an opening is formed at one end of the side wall; the side wall comprises a rolling groove, and the rolling groove comprises a first groove wall deviating from one side of the opening; the electrode assembly is arranged in the shell; the current collecting component comprises a current collecting body and a connecting piece connected to the periphery of the current collecting body, the current collecting body is electrically connected with the electrode assembly, and the connecting piece is bent towards the axis of the shell and is welded to the first groove wall to form a welding part; the welding part comprises a molten pool, the side, away from the axis of the shell, of the contour line of the molten pool intersects with the surface of the first groove wall to form a first intersection point, and an included angle alpha is formed between the tangent line, passing through the first intersection point, of the contour line and the first groove wall and is an obtuse angle. According to the utility model, the phenomenon that the welding part is easy to stretch and tear in the channeling process can be improved, so that the stability of electric connection between the current collecting component and the shell can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and in particular to a cylindrical battery, a battery pack and an electronic device. Background Art

[0002] At present, when assembling cylindrical batteries, laser welding is usually used to fix the current collecting component to the side wall of the shell. In the prior art, the welded portion formed by the welding connection between the current collecting component and the shell is prone to stretching and tearing during the subsequent groove rolling process, thereby reducing the stability of the electrical connection between the current collecting component and the shell and the finished product yield of the cylindrical battery. Utility Model Content

[0003] The utility model provides a cylindrical battery, a battery pack and an electronic device, which can improve the technical problem that the welding part formed by welding the current collecting component and the shell is easily stretched and torn during the groove rolling process, thereby reducing the stability of the electrical connection between the current collecting component and the shell.

[0004] To achieve the above-mentioned purpose and other related purposes, the utility model provides a cylindrical battery, which includes: a shell, an electrode assembly and a current collecting member, the shell includes a surrounding side wall, one end of the side wall forms an opening; the position of the side wall near the opening includes a rolling groove recessed into the shell, the rolling groove includes a first groove wall facing away from the opening; the electrode assembly is arranged in the shell, and the rolling groove limits the displacement of the electrode assembly in the axial direction of the shell; the current collecting member is at least partially arranged between the electrode assembly and the rolling groove; the current collecting member includes a current collecting body and a connecting piece connected to the periphery of the current collecting body, the current collecting body is electrically connected to the electrode assembly, the connecting piece is bent toward the axis of the shell and welded to the first groove wall to form a welding part; wherein the welding part includes a molten pool, and on the axial section of the cylindrical battery passing through the molten pool, the side of the contour line of the molten pool away from the axis of the shell intersects with the surface of the first groove wall facing the connecting piece to form a first intersection, and the tangent of the contour line passing through the first intersection forms an angle α away from the axial direction of the shell with the first groove wall, and the angle α is an obtuse angle.

[0005] In an example of the cylindrical battery of the present invention, the angle α ranges from 100° to 165°.

[0006] In an example of a cylindrical battery of the utility model, the area where the contour line is located inside the first groove wall includes a reference point with the smallest radius of curvature, the tangent of the contour line passing through the reference point is the first straight line, and the straight line passing through the reference point and perpendicular to the first straight line is the second straight line; the second straight line intersects the contour line to form a second intersection, the straight-line distance between the reference point and the second intersection is L, and 0.25mm≤L≤1mm.

[0007] In an example of the cylindrical battery of the utility model, the second straight line intersects with the surface of the first groove wall on the side away from the connecting piece to form a third intersection point, and the distance between the third intersection point and the reference point is greater than zero.

[0008] In an example of the cylindrical battery of the present invention, an angle β is formed between the second straight line and the first groove wall in the direction of the axis of the shell, and the angle β is in the range of 15° to 80°.

[0009] In an example of the cylindrical battery of the utility model, the contour line intersects with the surface of the side of the connecting piece away from the first groove wall, and forms a fourth intersection point on the side close to the axis of the shell and a fifth intersection point on the side away from the axis of the shell. The straight-line distance between the fourth intersection point and the fifth intersection point is A, and 0.3mm≤A≤2mm.

[0010] In an example of the cylindrical battery of the present invention, the distance between the fourth intersection and the end of the connecting piece away from the current collecting body is B, and 0.5 mm ≤ B ≤ 2 mm.

[0011] In an example of the cylindrical battery of the present invention, the thickness of the connecting sheet is 0.1-0.3 mm, and the thickness of the side wall is 0.3-0.8 mm.

[0012] In an example of the cylindrical battery of the present invention, a portion of the connecting sheet between the welding portion and the current collecting body does not contact the side wall.

[0013] The utility model also provides a battery pack, which includes the cylindrical battery in any of the above examples.

[0014] The present invention further provides an electronic device, which includes the battery pack in the above example.

[0015] In the cylindrical battery of the utility model, a first intersection is formed by making the side of the contour line of the molten pool away from the axis of the shell intersect with the surface of the first groove wall toward the connecting piece on the axial section of the cylindrical battery passing through the molten pool, and an angle α away from the axial direction of the shell is formed between the tangent of the contour line passing through the first intersection and the first groove wall, and the angle α is an obtuse angle. In this way, on the one hand, the angle between the side of the molten pool away from the axis of the shell and the first groove wall is increased, so that the stress concentration of the weld at this position is smaller, and because the position is close to the area where the connecting piece is bent relative to the first groove wall, the stress concentration of the weld at this position is reduced, which can effectively reduce the probability of tensile tearing of the weld, and improve the stability of the welded connection between the connecting piece and the side wall. On the other hand, since the angle α is an obtuse angle, the molten pool can be inclined as a whole along the thickness direction of the first groove wall, thereby forming an inclined weld mark. Compared with the non-inclined weld mark, the molten pool depth of the inclined weld mark can be deeper. The deeper the molten pool depth, the higher the welding strength of the molten pool. Therefore, the possibility of the weld mark being pulled apart will be reduced, thereby further improving the stability of the welding connection between the connecting piece and the side wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the utility model. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is a cross-sectional view of the overall structure of an embodiment of a cylindrical battery of the utility model;

[0018] Figure 2 for Figure 1 A partial enlarged view of the middle area A;

[0019] Figure 3 This is an enlarged view of the local structure at the welding part of an embodiment of the cylindrical battery of the utility model;

[0020] Figure 4 A schematic diagram of the position between the contour line of the molten pool and the first groove wall in an embodiment of a cylindrical battery of the utility model;

[0021] Figure 5 This is an enlarged view of the molten pool structure in one embodiment of the cylindrical battery of the utility model;

[0022] Figure 6 This is a schematic diagram of the structure of a cylindrical battery in an embodiment of the utility model before the groove is rolled;

[0023] Figure 7This is a schematic diagram of the welding position between the welding head and the side wall in an embodiment of the cylindrical battery of the utility model;

[0024] Figure 8 This is a schematic diagram of the position between the molten pool, the side wall and the connecting piece in an embodiment of a cylindrical battery of the utility model;

[0025] Fig. 9 This is a schematic diagram of the overall structure of an embodiment of a battery pack of the utility model;

[0026] Fig.10 This is a schematic diagram of the structure of the battery pack of the utility model installed on a vehicle.

[0027] Component number description

[0028] 100, cylindrical battery; 110, shell; 111, side wall; 112, opening; 113, rolling groove; 1131, first groove wall; 114, end wall; 115, extension; 116, connecting portion; 117, main body; 118, transition portion; 120, electrode assembly; 121, first pole ear; 122, second pole ear; 130, current collecting member; 131, current collecting body; 132, connecting piece; 1321, first bending portion; 140, welding portion; 141, molten pool; 1401, wheel Contour; 1402, straight contour; 1403, curved contour; 142, first intersection; 143, reference point; 144, first straight line; 145, second intersection; 146, third intersection; 147, fourth intersection; 148, fifth intersection; 149, second straight line; 150, end cover; 160, sealing ring; 170, welding head; 200, battery pack; 210, box; 211, first box part; 212, second box part; 300, electronic device; 310, working part. DETAILED DESCRIPTION

[0029] The following describes the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and the features in the embodiments can be combined with each other without conflict. It should also be understood that the terms used in the embodiments of the present invention are intended to describe specific implementation schemes, rather than to limit the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are usually carried out under conventional conditions or under the conditions recommended by the manufacturers.

[0030] When numerical ranges are given in the embodiments, it should be understood that unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention are in accordance with the prior art mastery of those skilled in the art and the description of the present invention, and any prior art methods, equipment and materials similar or equivalent to the methods, equipment and materials in the embodiments of the present invention can also be used to implement the present invention.

[0031] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present utility model. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present utility model without substantially changing the technical content.

[0032] See also Figures 1 to 10 The utility model provides a cylindrical battery 100, a battery pack 200 and an electronic device 300. In the axial section of the shell 110 of the cylindrical battery 100, the side of the contour line 1401 of the molten pool 141 away from the axis of the shell 110 intersects with the surface of the first groove wall 1131 facing the connecting piece 132 to form a first intersection 142, and an obtuse angle away from the axis direction of the shell 110 is formed between the tangent of the contour line 1401 passing through the first intersection 142 and the first groove wall 1131. Such an arrangement can reduce the stress concentration generated on the side of the welding portion 140 away from the axis of the shell 110, thereby reducing the probability of tensile tearing of the welding portion 140 and improving the stability of the electrical connection between the current collecting member 130 and the shell 110.

[0033] See also Figure 1 and Figure 2 , further describing the structure of the cylindrical battery 100, the cylindrical battery 100 includes: a shell 110, an electrode assembly 120 and a current collecting member 130. A accommodating cavity is formed in the shell 110 for accommodating the electrode assembly 120, the electrolyte and other components. The shell 110 can be an open structure at one end or an open structure at both ends. The specific size of the shell 110 can be determined according to the specific size of the electrode assembly 120, for example, to meet the specifications of 4680, 4695, 46120, etc. of large cylindrical batteries. The material of the shell 110 can be selected from a variety of options, such as copper, iron, aluminum, steel, aluminum alloy, etc. In order to prevent the shell 110 from rusting during long-term use, a layer of rust-proof material, such as metal nickel, etc., can also be plated on the surface of the shell 110.

[0034] See also Figures 1 to 3In an example of the cylindrical battery 100 of the utility model, the shell 110 is a cylindrical structure, and the shell 110 includes an end wall 114 and a side wall 111 surrounding the end wall 114, that is, the shell 110 includes a closed end and an open end, the end wall 114 is a closed end, and the opening 112 opposite to the end wall 114 is an open end. The side wall 111 is formed with a rolling groove 113 recessed toward the inside of the shell 110 on the side facing the opening 112, and the rolling groove 113 has a first groove wall 1131 on the side facing away from the opening 112. The cross-sectional shape of the rolling groove 113 can be any shape that meets the use requirements, such as a rectangle, a square or a trapezoid; the side wall 111 is also provided with an extension portion 115 extending toward the center of the opening 112 on the side of the rolling groove 113 close to the opening 112, and a connecting portion 116 is also provided between the extension portion 115 and the rolling groove 113, and the extension portion 115 is connected to the rolling groove 113 through the connecting portion 116. It should be noted that the specific sizes of the rolling groove 113 , the extension portion 115 , and the connection portion 116 need to be determined according to the size specifications of the cylindrical battery 100 , and in this embodiment, no specific limitation is made thereto.

[0035] like Figure 1 and Figure 2 As shown, the electrode assembly 120 is contained in the housing 110. The electrode assembly 120 is a component in the cylindrical battery 100 where an electrochemical reaction occurs. The housing 110 may contain one or more electrode assemblies 120. The electrode assembly 120 is mainly formed by winding or stacking a positive electrode sheet and a negative electrode sheet, and a separator is usually provided between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode collector and a positive electrode active material layer, and the positive electrode active material layer is coated on the surface of the positive electrode collector; the positive electrode collector includes a positive electrode coating area and a positive electrode ear connected to the positive electrode coating area, the positive electrode coating area is coated with a positive electrode active material layer, and the positive electrode ear is not coated with a positive electrode active material layer. The negative electrode sheet includes a negative electrode collector and a negative electrode active material layer, and the negative electrode active material layer is coated on the surface of the negative electrode collector; the negative electrode collector includes a negative electrode coating area and a negative electrode ear connected to the negative electrode coating area, the negative electrode coating area is coated with a negative electrode active material layer, and the negative electrode ear is not coated with a negative electrode active material layer. Taking lithium-ion batteries as an example, the material of the positive electrode current collector can be aluminum, and the positive electrode active material layer includes the positive electrode active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide. The material of the negative electrode current collector can be copper, and the negative electrode active material layer includes the negative electrode active material, which can be carbon or silicon. The material of the diaphragm can be PP or PE. In order to protect and insulate the electrode assembly 120, an insulating film can also be coated on the outside of the electrode assembly 120, and the insulating film can be synthesized from PP, PE, PET, PVC or other high molecular polymer materials.

[0036] See also Figure 1 and Figure 2In an example of the cylindrical battery 100 of the utility model, the electrode assembly 120 is sealed and installed in the housing 110. Along the height direction of the cylindrical battery 100, the electrode assembly 120 is arranged between the end wall 114 and the rolling groove 113, and the rolling groove 113 can limit the axial movement of the electrode assembly 120 between the end wall 114 and the rolling groove 113. The electrode assembly 120 is respectively provided with a first pole ear 121 and a second pole ear 122 at both ends of the height direction of the cylindrical battery 100, and the polarities of the first pole ear 121 and the second pole ear 122 are opposite, wherein the first pole ear 121 faces the side of the opening 112, and the first pole ear 121 is a negative pole ear. It should be noted that in other embodiments, the first pole ear 121 can also be a positive pole ear, and the second pole ear 122 is a negative pole ear.

[0037] See also Figure 1 and Figure 2 The end cover 150 is disposed at the opening 112 , and the outer periphery of the end cover 150 is clamped between the extension portion 115 , the connecting portion 116 and the rolling groove 113 through a sealing ring 160 to achieve a sealed and fixed connection of the end cover 150 at the opening 112 .

[0038] The current collecting component 130 is disposed in the housing 110 and is located between the end cover 150 and the electrode assembly 120. The current collecting component 130 includes a current collecting body 131 and a connecting piece 132 connected to the periphery of the current collecting body 131. There are multiple options for connection methods, such as welding connection, integral molding connection, and any other connection method that can achieve electrical connection between the connecting piece 132 and the current collecting body 131. In this embodiment, in order to improve assembly efficiency, the connecting piece 132 and the current collecting body 131 are an integral stamping part. The current collecting body 131 is electrically connected to the first pole ear 121, and there are multiple options for electrical connection methods, such as welding connection, conductive adhesive bonding connection, and any other method that can achieve electrical connection between the connecting piece 132 and the first pole ear 121. In this embodiment, the current collecting body 131 and the first pole ear 121 are welded. It should be noted that the connection sheet 132 is arranged at the periphery of the current collecting body 131, which means that the connection sheet 132 is connected to the outer edge of the current collecting body 131 along the radial direction of the current collecting body 131. The number of connection sheets 132 can be one or more, depending on the flow guidance requirements between the current collecting member 130 and the shell 110. Preferably, in this embodiment, the current collecting member 130 includes a plurality of connection sheets 132, and the plurality of connection sheets 132 are arranged around the outer periphery of the current collecting body 131. In this way, a more uniform flow guidance effect can be generated in the circumferential direction of the current collecting member 130 and the side wall 111, thereby improving the stability of the flow guidance between the shell 110 and the electrode assembly 120.

[0039] See also Figure 2 and Figure 3, the connecting piece 132 is located on the side of the current collecting body 131 away from the electrode assembly 120, one end of the connecting piece 132 is connected to the periphery of the current collecting body 131, and the other end of the connecting piece 132 is bent toward the axis of the shell 110 and welded to the first slot wall 1131 to form a welding portion 140. The specific shape of the bending of the connecting piece 132 is not limited. For example, the connecting piece 132 can be approximately U-shaped, approximately triangular, etc. after bending, so as to ensure that a welding portion 140 that meets the connection strength requirements is formed between a partial area of ​​the connecting piece 132 and the first slot wall 1131. By arranging the connecting piece 132 on the periphery of the current collecting body 131, the welding connection between the current collecting component 130 and the shell 110 can be facilitated, and the welding position between the current collecting component 130 and the shell 110 can be more flexible.

[0040] It should be noted that, because the material of the connecting piece 132 is usually softer than that of the shell 110, after the groove is rolled, the end of the connecting piece 132 close to the welding portion 140 will be bent on the side of the welding portion 140 away from the axis of the shell 110 to form a first bent portion 1321. Figure 3 shown.

[0041] See also Figure 3 and Figure 4 The welding portion 140 formed between the connecting piece 132 and the first groove wall 1131 includes a molten pool 141. On the axial section of the cylindrical battery 100 passing through the molten pool 141, the molten pool 141 forms a contour line 1401. The contour line 1401 of the molten pool 141 includes a straight contour 1402 formed on the side of the second connecting portion 116 facing the electrode assembly 120 and a curved contour 1403 formed on the side of the second connecting portion 116 away from the electrode assembly 120. The opening direction of the curved contour 1403 faces the side of the electrode assembly 120, and the two ends of the straight contour 1402 are respectively connected to the two ends of the curved contour 1403. The curved contour 1403 at least partially extends to the inside of the first groove wall 1131. Along the radial direction of the housing 110, the side of the curved profile 1403 away from the axis of the housing 110 intersects with the surface of the first groove wall 1131 facing the connecting piece 132, and forms a first intersection 142. The tangent line of the curved profile 1403 passing through the first intersection 142 (such as Figure 4 An obtuse angle α is formed between the first groove wall 1131 and the straight line XX in the middle) and the first groove wall 1131, which is away from the axial direction of the housing 110. It should be noted that, since there are often some errors in welding parameters during the actual welding process, the curved profile 1403 in the embodiment of the present application is a curved line segment that is roughly smoothly connected, and some sudden irregular line segments are allowed to exist at the local position of the curved line segment; similarly, the straight profile 1402 is also a line segment that is roughly connected in a straight line, and some sudden irregular line segments are also allowed to exist at the local position of the straight line shape.

[0042] In the cylindrical battery 100 of the utility model, since an obtuse angle α is set, on the one hand, the angle between the side of the molten pool 141 away from the axis of the shell 110 and the first groove wall 1131 is increased, so that the stress concentration of the welding part 140 at this position is small, so that the connection strength of the welding part 140 at this position can be increased, and the probability of tensile tearing of the welding part 140 can be effectively reduced, so that the stability of the welding connection between the connecting piece 132 and the side wall 111 can be correspondingly improved. On the other hand, since the angle α is an obtuse angle, the molten pool 141 can be inclined along the thickness direction of the first groove wall 1131 as a whole, thereby forming an inclined welding part 140. Compared with the non-inclined welding part 140, the depth of the molten pool 141 of the inclined welding part 140 can be deeper, and the deeper the depth of the molten pool 141, the higher the welding strength of the welding part 140, so the possibility of the welding part 140 being pulled off is reduced, thereby further improving the stability of the welding connection between the connecting piece 132 and the side wall 111.

[0043] In an example of the cylindrical battery 100 of the utility model, the angle α is any value between 100° and 165°, for example, the angle α can be 100°, 130°, 150° or 165°. Limiting the angle α within the range of 100° to 165° can not only obtain a better depth of the molten pool 141 between the first groove wall 1131 and the connecting piece 132, thereby ensuring the welding quality of the weld 140, but also the angle α within the range of 100° to 165° can also ensure that when the weld 140 is formed, the welding head 170 and the side wall 111 have a better welding posture, thereby ensuring the forming efficiency of the weld 140.

[0044] See also Figure 4 and Figure 5In an example of the cylindrical battery 100 of the utility model, the curved profile 1403 at least partially extends to the inside of the first groove wall 1131, and the area of ​​the curved profile 1403 located inside the first groove wall 1131 includes the reference point 143 with the smallest radius of curvature. The tangent line of the curved profile 1403 passing through the reference point 143 is the first straight line 144, and the straight line passing through the reference point 143 and extending in a direction perpendicular to the first straight line 144 is the second straight line 149. With the reference point 143 as the boundary, one end of the second straight line 149 extends toward one side of the connecting piece 132 and intersects with the straight profile 1402 to form a second intersection 145, and the straight line distance between the reference point 143 and the second intersection 145 is L, and 0.25mm≤L≤1mm. The other end of the second straight line 149 extends toward the side away from the second intersection 145, penetrates the first groove wall 1131, and intersects with the surface of the first groove wall 1131 away from the connecting piece 132 to form a third intersection 146. The distance between the third intersection 146 and the reference point 143 is greater than zero. This arrangement can limit the molten pool 141 to the side of the first groove wall 1131 away from the connecting piece 132, ensuring that the first groove wall 1131 will not be welded through, thereby taking into account both the welding quality of the welding portion 140 and the aesthetics of the outer surface of the housing 110.

[0045] Specifically, the size of L can be any value within the range of 0.25 to 1 mm, such as 0.25 mm, 0.05 mm or 1 mm. The dimension L is set to be the effective depth of the molten pool 141. The greater the effective depth of the molten pool 141, the larger the welding process window of the welding portion 140, and the lower the welding difficulty. However, if the effective depth of the molten pool 141 is too large, there will be a risk of the side wall 111 being welded through, increasing the welding defect rate of the product. In view of this, in this embodiment, by limiting the size of the dimension L to within the range of 0.25 mm ≤ L ≤ 1 mm, it can be ensured that the effective depth of the molten pool 141 is within a reasonable size range, that is, the process window of the welding portion 140 is increased, the welding difficulty is reduced, and the welding connection strength requirements between the shell 110 and the connecting piece 132 in the conventional cylindrical battery 100 can be met. At the same time, since the dimension L is inclined to the first groove wall 1131, under the premise that the thickness of the shell 110 and the connecting plate 132 remains unchanged, the inclined molten pool 141 structure in this embodiment can effectively increase the effective depth of the molten pool 141, thereby further increasing the welding process window and reducing the difficulty of welding.

[0046] See also Figure 5 In one example of the cylindrical battery 100 of the utility model, an angle β is formed between the second straight line 149 and the first groove wall 1131 toward the axial direction of the housing 110, and the angle β is any value within the range of 15° to 80°, for example, 15°, 30°, 50° or 80°. Figure 8 , Figure 8 Schematic diagram of the position between the welding head 170 and the side wall 111 during the welding process before the groove rolling. Figure 5 and Figure 8 , without considering the rolling groove error, Figure 8 The angle γ between the axis of the welding head 170 and the side wall 111 is Figure 5 Therefore, in this embodiment, by limiting the angle β to a range of 15° to 80°, it is equivalent to Figure 8 The angle γ in the welding process is limited to a range of 15° to 80°. Since the size of the angle β directly affects the inclination of the molten pool 141, and the size of the angle γ directly affects the welding posture of the welding head 170, the inclination of the molten pool 141 and the welding posture of the welding head 170 can be considered by limiting β to between 15° and 80°, and the welding of the welding head 170 can be facilitated while ensuring that the molten pool 141 has a better effective depth of the molten pool 141.

[0047] See also Figure 4 and Figure 5 In an example of the cylindrical battery 100 of the utility model, the curved profile 1403 intersects with the surface of the side of the connecting piece 132 away from the first groove wall 1131, that is, the curved profile 1403 intersects with the straight profile 1402. The curved profile 1403 intersects with the straight profile 1402 to form a fourth intersection 147 close to the axis side of the shell 110 and a fifth intersection 148 away from the axis side of the shell 110. The straight-line distance between the fourth intersection 147 and the fifth intersection 148 is A, and 0.3mm≤A≤2mm. For example, the size of A can be any value within the range of 0.3 to 2mm, such as 0.3mm, 1mm or 2mm. Under certain welding parameters, the size of size A is positively correlated with the area of ​​the molten pool 141 formed on the connecting piece 132. The larger the area of ​​the molten pool 141 formed on the connecting piece 132, the better the welding strength of the welding part 140. However, the larger the space occupied by the molten pool 141 on the surface of the connecting piece 132, the easier it is to interfere with the groove rolling position, increasing the probability of the welding part 140 being damaged during the groove rolling process. On the contrary, the weaker the welding strength of the welding part 140, the smaller the space occupied by the molten pool 141 on the surface of the connecting piece 132, the less likely it is to interfere with the groove rolling position, reducing the probability of the welding part 140 being damaged during the groove rolling process. In this embodiment, by limiting the dimension A to the range of 0.3 to 2 mm, it can ensure that the welding part 140 has a better welding connection strength, and the welding part 140 can avoid the groove rolling position, thereby ensuring the integrity of the welding part 140 during the groove rolling process.

[0048] See also Figure 5In an example of the cylindrical battery 100 of the utility model, the distance between the fourth intersection 147 and the end of the connecting piece 132 away from the current collector 131 is B, and 0.5mm≤B≤2mm. For example, the size of B can be any value within the range of 0.5 to 2mm, such as 0.5mm, 1mm or 2mm. Figure 5 and Figure 8 , we can know Figure 8 The upper edge of the middle welding portion 140 near the opening 112 intersects with the surface of the connecting piece 132 facing away from the side wall 111 to form an intersection F. The distance between the intersection F and the end of the connecting piece 132 facing the opening 112 is a dimension C. The dimension C is equal to Figure 5 The dimension B in is roughly equal, that is, without considering the deformation of the connecting piece 132 during the groove rolling process, the dimension C is the dimension B. Figure 8 As shown, the size of dimension C directly affects the distribution position of the welding portion 140 on the connecting piece 132, and the larger the dimension C, the lower the position of the welding portion 140, that is, the closer to the electrode assembly 120. When the welding portion 140 is closer to the electrode assembly 120, it is easier to damage the tab on the electrode assembly 120 during welding, and the welding head 170 is more likely to interfere with the electrode assembly 120 during welding, affecting the welding efficiency and welding quality. Anyway, when the position of the welding portion 140 is closer to the opening 112 side, the welding portion 140 is more likely to interfere with the rolling groove 113, so that the welding portion 140 is easily damaged when the rolling groove 113 is rolled, affecting the assembly yield of the product. Therefore, in this embodiment, by limiting the dimension B to between 0.5 and 2 mm, the dimension C can be limited, that is, the dimension C is also limited to between 0.5 and 2 mm. In this way, the distribution position of the welding portion 140 on the connecting piece 132 can reduce the damage to the electrode assembly 120 during the welding process, facilitate the welding of the welding head 170, and ensure the welding efficiency; it can also reduce the damage to the welding portion 140 during the grooving process and ensure the integrity of the welding portion 140.

[0049] In an example of the cylindrical battery 100 of the utility model, the thickness of the connecting piece 132 is any value in the range of 0.1 to 0.3 mm, for example, it can be 0.1 mm, 0.2 mm or 0.3 mm. The thickness of the side wall 111 is any value in the range of 0.3 to 0.8 mm, for example, it can be 0.3 mm, 0.5 mm or 0.8 mm. The thickness of the connecting piece 132 affects the welding efficiency of the laser penetration welding. The greater the thickness, the greater the welding power required for welding, and the greater the power consumption; at the same time, when the welding power is large, the side wall 111 is more likely to be welded through, resulting in welding failure and an increase in the defective rate of the product. On the premise that the thickness of the shell 110 remains unchanged, the smaller the thickness of the connecting piece 132, the smaller the welding power required for welding, but the smaller the depth of the molten pool 141 formed on the side wall 111, the weaker the welding strength. Therefore, in this embodiment, by setting the thickness of the connecting piece to 0.1-0.3 mm and the thickness of the side wall 111 to 0.3-0.8 mm, not only can the connecting piece 132 be easily penetrated by the laser during welding, thereby reducing the loss of welding power, but also it can ensure that a better depth of the molten pool 141 is formed on the side wall 111, meet the welding strength requirements of the welding portion 140, improve the stability of the electrical connection between the connecting piece 132 and the side wall 111, and improve the yield of the cylindrical battery 100.

[0050] See also Figures 1 to 3 In one example of the cylindrical battery 100 of the present invention, the portion of the connecting piece 132 between the welding portion 140 and the current collecting body 131 does not contact the side wall 111. Figure 2 As shown, the side wall 111 is further formed with a main body 117 between the rolling groove 113 and the end wall 114, and the main body 117 extends along the height direction of the cylindrical battery 100; the side wall 111 is further formed with a transition portion 118 at one end of the rolling groove 113 and the main body 117 away from the end wall 114. One end of the transition portion 118 is connected to the end of the first groove wall 1131 away from the center of the shell 110, and the other end of the transition portion 118 is connected to the end of the main body 117 away from the end wall 114; the structural shape of the transition portion 118 can be any structure that can achieve a smooth transition connection between the main body 117 and the rolling groove 113, such as an arc surface structure, an inclined surface structure, etc. The connection position between the connecting piece 132 and the current collecting body 131 is set as point K, and the part of the connecting piece 132 between point K and the first intersection 142 does not contact the side wall 111. In the present embodiment, not in contact with the side wall 111 specifically means that the portion of the connecting piece 132 between point K and the first intersection 142 does not contact the surface of the first groove wall 1131 on the side facing the connecting piece 132, the inner wall of the transition portion 118, and the inner wall of the main body 117 at the connection position with the transition portion 118.

[0051] With such arrangement, on the one hand, since the portion of the connecting piece 132 between point K and the first intersection 142 does not contact the side wall 111, when the groove 113 is rolled on the shell 110, the welding portion 140 will not be subjected to the additional squeezing force exerted by the side wall 111 on the connecting piece 132. Therefore, the integrity of the welding portion 140 can be better protected, and the stability of the electrical connection between the electrode assembly 120 and the shell 110 and the yield rate of the cylindrical battery 100 are correspondingly improved, thereby ensuring the performance of the cylindrical battery 100. On the other hand, since the portion of the connecting piece 132 between point K and the first intersection 142 after grooving does not contact the side wall 111, a gap is formed. It can be further known that when the current collecting component 130 is installed into the shell 110 before grooving, a gap is formed between the outer edge of the connecting piece 132 close to the electrode assembly 120 and the inner surface of the side wall 111, and the end of the connecting piece 132 away from the electrode assembly 120 can overlap the side wall 111, forming an inclined overlapping arrangement between the connecting piece 132 and the side wall 111, which not only facilitates the insertion of the current collecting component 130 into the shell, but also forms a welding portion 140 with a larger cross-sectional area between the connecting piece 132 and the side wall 111, thereby improving the welding strength between the connecting piece 132 and the side wall 111.

[0052] See also Fig. 9 In one embodiment of the battery pack 200 of the utility model, the battery pack 200 includes a box body 210 and at least one cylindrical battery 100; the box body 210 includes a first box body part 211 and a second box body part 212, the first box body part 211 and the second box body part 212 cover each other to form a receiving space, and multiple cylindrical batteries 100 are received in the receiving space, and the multiple cylindrical batteries 100 can be connected in series and / or in parallel. The battery pack 200 can be, for example, a battery module, a battery pack, etc.

[0053] See also Fig.10In an example of the electronic device 300 of the utility model, the electronic device 300 includes a working part 310 and a battery pack 200, and the working part 310 is electrically connected to the battery pack 200 to obtain power support. The working part 310 can be a unit component that can obtain power from the battery pack 200 and perform corresponding work, such as a fan blade rotation unit, a vacuum cleaner unit, a wheel drive unit in an electric car, etc. The electronic device 300 can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc. The vehicle may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc.; the spacecraft includes airplanes, rockets, space shuttles and spacecrafts, etc.; the electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc.; the electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators and electric planers, etc. The embodiment of the utility model does not impose any special restrictions on the above-mentioned electronic device 300. In one embodiment of the electronic device 300 of the utility model, the electronic device 300 is a vehicle, the working part 310 is the body of the vehicle, and the battery pack 200 is fixedly installed on the body, thereby providing driving force for the vehicle to realize the operation of the vehicle.

[0054] In the cylindrical battery of the utility model, due to the setting of the obtuse angle α, on the one hand, the angle between the side of the molten pool away from the axis of the shell and the first groove wall is increased, so that the stress concentration of the welding part at this position is small, and because the position is close to the first bending part of the connecting piece, the deformation stress generated by the first bending part is easily transmitted to the welding part, increasing the tensile stress borne by the welding part, so as to reduce the stress concentration of the welding part close to the first bending part, which can effectively reduce the probability of tensile tearing of the welding part and improve the stability of the welding connection between the connecting piece and the side wall. On the other hand, since the angle α is an obtuse angle, the molten pool can be made to present an inclined structure as a whole along the thickness direction of the first groove wall, and the end of the molten pool away from the connecting piece is inclined toward the direction away from the axis of the shell, so that the connection strength of the welding part close to the first bending part can be increased in a targeted manner, thereby further improving the stability of the welding connection between the connecting piece and the side wall. Therefore, the utility model effectively overcomes some practical problems in the prior art and has a high utilization value and use significance. The above embodiments are only illustrative of the principle and effect of the utility model, and are not used to limit the utility model. Anyone familiar with the technology can modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the relevant technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A cylindrical battery, characterized in that: include: The shell comprises a surrounding side wall, one end of which forms an opening; the side wall comprises a rolling groove recessed toward the inside of the shell at a position close to the opening, and the rolling groove comprises a first groove wall facing away from the opening; An electrode assembly is disposed in the shell, and the rolling groove limits the displacement of the electrode assembly in the axial direction of the shell; a current collecting member, at least partially disposed between the electrode assembly and the rolling groove; the current collecting member comprises a current collecting body and a connecting piece connected to the periphery of the current collecting body, the current collecting body is electrically connected to the electrode assembly, the connecting piece is bent toward the axis of the shell and welded to the first groove wall to form a welding portion; Wherein, the welding portion includes a molten pool, and on the axial section of the cylindrical battery passing through the molten pool, the side of the contour line of the molten pool away from the axis of the shell intersects with the surface of the first groove wall toward the connecting piece to form a first intersection, and the tangent of the contour line passing through the first intersection forms an angle α with the first groove wall that deviates from the axial direction of the shell, and the angle α is an obtuse angle.

2. The cylindrical battery according to claim 1, characterized in that: The angle α ranges from 100° to 165°.

3. The cylindrical battery according to claim 1, characterized in that: The area where the contour line is located inside the first groove wall includes a reference point with the smallest curvature radius, the tangent of the contour line passing through the reference point is the first straight line, and the straight line passing through the reference point and perpendicular to the first straight line is the second straight line; the second straight line intersects with the contour line to form a second intersection, the straight-line distance between the reference point and the second intersection is L, and 0.25mm≤L≤1mm.

4. The cylindrical battery according to claim 3, characterized in that: The second straight line intersects with the surface of the first groove wall on a side away from the connecting piece to form a third intersection point, and a distance between the third intersection point and the reference point is greater than zero.

5. The cylindrical battery according to claim 3, characterized in that: An included angle β is formed between the second straight line and the first groove wall in the axial direction of the housing, and the included angle β is in the range of 15° to 80°.

6. The cylindrical battery according to claim 1, characterized in that: The contour line intersects with the surface of the connecting plate on one side facing away from the first groove wall, and forms a fourth intersection point close to the axis side of the shell and a fifth intersection point away from the axis side of the shell, and the straight-line distance between the fourth intersection point and the fifth intersection point is A, and 0.3mm≤A≤2mm.

7. The cylindrical battery according to claim 6, characterized in that: The distance between the fourth intersection and the end of the connecting piece away from the current collecting body is B, and 0.5 mm≤B≤2 mm.

8. The cylindrical battery according to claim 1, characterized in that: The thickness of the connecting sheet is 0.1-0.3 mm, and the thickness of the side wall is 0.3-0.8 mm.

9. The cylindrical battery according to any one of claims 1 to 8, characterized in that: A portion of the connection piece between the welding portion and the current collecting body does not contact the side wall.

10. A battery pack, characterized in that: The battery pack comprises the cylindrical battery according to any one of claims 1 to 9.

11. An electronic device, characterized in that: A battery pack comprising the battery pack of claim 10.

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