Secondary battery, battery pack, and electronic device

Abstract

The utility model provides a secondary battery, comprising: a housing comprising an end wall and a side wall surrounding the end wall, the end wall having a first assembly hole; the lower plastic cement is arranged on one side, facing the inner surface of the interior of the shell, of the end wall, and the lower plastic cement is provided with a second assembly hole corresponding to the first assembly hole; the pole penetrates through the first assembly hole and the second assembly hole, the pole comprises an inner flange, and the inner flange is located on the side, opposite to the end wall, of the lower plastic and clamps the lower plastic together with the end wall; in the radial direction of the shell, the inner flange presses the lower plastic through riveting, and at least part of the edge of the inner flange is pressed into the lower plastic. The utility model aims to provide a secondary battery, a battery pack and an electronic device so as to at least improve the pole riveting strength of the battery.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of secondary battery, battery pack and electronic device. BACKGROUND

[0002] In the field of new energy power battery, secondary battery generally includes electrode assembly, shell, cover plate and the like. Electrode assembly includes positive pole piece, negative pole piece and diaphragm between positive pole piece and negative pole piece, these positive pole piece, negative pole piece and diaphragm are wound into electrode assembly after mutual stacking, then encapsulated in shell. Under normal circumstances, lower plastic is arranged between electrode assembly and end wall of shell, for preventing electrode assembly from moving, and play the role of insulation. SUMMARY

[0003] In view of the problems in the related art, the utility model aims to provide a kind of secondary battery, battery pack and electronic device, to at least enhance the riveting strength of the pole of battery, and enhance the stability of riveting.

[0004] To achieve the above object, the utility model provides a kind of secondary battery, the secondary battery includes: shell, including end wall and the side wall around end wall, end wall has first assembly hole;Lower plastic is arranged in the inner surface side of end wall facing the inside of shell, lower plastic has the second assembly hole corresponding with first assembly hole;Pole is passed through first assembly hole and second assembly hole, pole includes inner flange, inner flange is located on the side of lower plastic away from end wall and is held lower plastic with end wall together;Wherein, along the radial direction of shell, inner flange is pressed by riveting lower plastic, and the edge of inner flange is at least partially pressed into lower plastic.

[0005] In some embodiments, inner flange has first surface extending along the edge of radial direction beyond first assembly hole and facing end wall, and at least part of the surface of first surface extends towards end wall away from the edge of first assembly hole.

[0006] In some embodiments, along the axial direction of first assembly hole, the depth that inner flange is pressed into lower plastic is A, wherein 0.02mm≤A≤0.2mm.

[0007] In some embodiments, in the plane perpendicular to radial direction and passing through the center of first assembly hole, maximum depth A includes first maximum depth A1 and second maximum depth A2 on the opposite side of pole along radial direction, and the difference between first maximum depth A1 and second maximum depth A2 is less than 0.05mm.

[0008] In some embodiments, inner flange has width W along radial direction, and the distance that the outermost end of inner flange exceeds the edge of first assembly hole is width W, wherein 0.8mm≤W≤3mm.

[0009] In some embodiments, in a plane perpendicular to the radial direction and passing through the center of the first assembly hole, the width W includes a first width W1 and a second width W2 on opposite sides of the pole in the radial direction, and a difference between the first width W1 and the second width W2 is less than 0.3 mm.

[0010] In some embodiments, in an axial direction of the first assembly hole, the inner flange has a maximum thickness B, where 0.6 mm≤B≤1.5 mm.

[0011] In some embodiments, in a plane perpendicular to the radial direction and passing through the center of the first assembly hole, the maximum thickness B includes a first maximum thickness B1 and a second maximum thickness B2 on opposite sides of the pole in the radial direction, and a difference between the first maximum thickness B1 and the second maximum thickness B2 is less than 0.1 mm.

[0012] In some embodiments, the pole further includes an outer flange located outside the housing, and the secondary battery further includes a sealing insulation member located between an outer surface of the end wall facing the outside of the housing and the outer flange of the pole, where, in an axial direction of the first assembly hole, the sealing insulation member has a thickness C between the outer surface of the end wall and the pole, and 0.4 mm≤C≤1.0 mm.

[0013] In some embodiments, in a plane perpendicular to the radial direction and passing through the center of the first assembly hole, the thickness C includes a first thickness C1 and a second thickness C2 on opposite sides of the pole in the radial direction, and a difference between the first thickness C1 and the second thickness C2 is less than or equal to 0.05 mm.

[0014] In some embodiments, a lower plastic is further disposed within the first assembly hole and between the pole and the end wall in the radial direction, the lower plastic has an end surface located within the first assembly hole and facing away from the inner flange, in an axial direction of the first assembly hole, the end surface of the lower plastic is farther away from the inner flange than the outer surface of the end wall, and a distance between the end surface and the outer surface is D, where 0.03≤D≤0.3 mm.

[0015] In some embodiments, in a plane perpendicular to the radial direction and passing through the center of the first assembly hole, the distance D includes a first distance D1 and a second distance D2 on opposite sides of the pole in the radial direction, and a difference between the first distance D1 and the second distance D2 is less than 0.05 mm.

[0016] In some embodiments, the pole further includes a main body connected to the inner flange, the main body passes through the first assembly hole and the second assembly hole, the main body includes a welding surface facing the inside of the housing, the welding surface is concave relative to the inner flange in an axial direction of the first assembly hole beyond a surface of the lower plastic facing away from the end wall, and a maximum distance between the welding surface and the lower plastic in contact with the inner flange is H, where 0.02 mm≤H≤0.2 mm.

[0017] Embodiments of the present application also provide a battery pack including the secondary battery of any one of the above.

[0018] Embodiments of the present application also provide an electronic device comprising the above battery pack.

[0019] The beneficial technical effects of the present application are as follows:

[0020] By configuring the inner flange to press the lower plastic by riveting, and the edge of the inner flange is at least partially pressed into the interior of the lower plastic, the riveting strength of the pole can be improved. In addition, the configuration of some dimensions related to the pole and the dimensional consistency can improve the stability of the riveting of the pole in different batches of batteries, and further improve the riveting strength of the pole and the strength of the pole. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0022] Figure 1 A perspective view of a secondary battery according to an embodiment of the present application is shown.

[0023] Figure 2 A top view of a secondary battery is shown.

[0024] Figure 3 A cross-sectional view taken along the X-X line of Figure 2 is shown.

[0025] Figure 4 A partial enlarged view of the area Ap in Figure 3 is shown.

[0026] Figure 5 A distance H according to an embodiment of the present application is shown.

[0027] Figure 6 A schematic view of an electronic device according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0028] In order to better understand the spirit of the embodiments of the present application, the following will further describe the embodiments of the present application in combination with some preferred embodiments of the present application.

[0029] Embodiments of this application will be described in detail below. Throughout this specification, identical or similar components and components having identical or similar functions are indicated by similar reference numerals. The embodiments described herein with reference to the accompanying drawings are illustrative and diagrammatic in nature and are intended to provide a basic understanding of this application. The embodiments of this application should not be construed as limiting this application.

[0030] As used herein, the terms “approximately,” “generally,” “substantially,” and “about” are used to describe and indicate minor variations. When used in conjunction with an event or situation, these terms may refer to examples in which the event or situation occurred precisely or in examples in which the event or situation occurred very approximately.

[0031] In this specification, unless otherwise specified or limited, relative terms such as “central,” “longitudinal,” “lateral,” “front,” “rear,” “right,” “left,” “inner,” “outer,” “lower,” “higher,” “horizontal,” “vertical,” “above,” “below,” “above,” “below,” “top,” “bottom,” and their derivatives (e.g., “horizontally,” “downward,” “upward,” etc.) should be interpreted as referring to the directions described in the discussion or depicted in the accompanying drawings. These relative terms are used for descriptive convenience only and do not require that this application be constructed or operated in a particular orientation.

[0032] For ease of description, "first," "second," "third," etc., can be used in this article to distinguish different components of a figure or a series of figures. "First," "second," "third," etc., are not intended to describe the corresponding components.

[0033] In the field of rechargeable batteries, existing technologies mostly employ an internal riveting structure within the battery casing to ensure the stability and accuracy of battery dimensions. However, this internal riveting structure involves riveting within the battery casing, which is a complex process with numerous steps, resulting in insufficient riveting strength and poor dimensional stability between different batches of products. Embodiments of this application provide a rechargeable battery to at least address this technical problem.

[0034] Figure 1 A perspective view of a secondary battery 100 according to an embodiment of this application is shown. Figure 2 A top view of the secondary battery 100 is shown. Figure 3 It shows along Figure 2 A cross-sectional view taken from the XX line. For clarity, Figure 3 Some components inside the casing are omitted.

[0035] According to the embodiments of this application, refer to Figures 1 to 3As shown, the secondary battery 100 can include a case 200, which can include an end wall 111 and a side wall 112 surrounding the end wall 111. The side wall 112 is connected to an edge of the end wall 111. The end wall 111 and the side wall 112 can define a receiving cavity 105 to accommodate an electrode assembly (not shown) of the secondary battery 100.

[0036] The connection between the end wall 111 and the side wall 112 can be achieved in various ways, such as one-piece stamping, one-piece casting, or separate welding, as long as a stable sealing and electrical connection relationship can be formed. The side wall 112 can surround in a cylindrical or prismatic shape, or any other closed-loop profile that can be matched with the end wall. The case 200 has a receiving cavity formed therein to accommodate the electrode assembly, electrolyte, lower plastic 30, current collector plate, and other necessary components of the battery. Specifically, the diameter of the case 200 can be determined according to the size of the electrode assembly. The case 200 can be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. To prevent rusting of the case 200 during long-term use, the case 200 can be plated with a rust-resistant material such as metallic nickel on the surface thereof. The secondary battery 100 can be a cylindrical battery, such as a 4680 cylindrical battery having a height of 80 mm and a diameter of 46 mm, or a cylindrical battery having a height of 15 mm and a diameter of 46 mm.

[0037] The secondary battery 100 can further include a lower plastic 30 and a pole 50. The lower plastic 30 is disposed on an inner surface 111a of the end wall 111 facing the inside of the case. The end wall 111 has a first assembly hole 118. The lower plastic 30 has a second assembly hole 119 corresponding to the first assembly hole 118. The pole 50 passes through the first assembly hole 118 and the second assembly hole 119. The pole 50 includes an inner flange 52 located below a surface 30a of the lower plastic 30 facing away from the end wall 111, and the inner flange 52 and the end wall 111 together clamp the lower plastic 30. The inner flange 52 can be in contact with the surface 30a of the lower plastic 30. The lower plastic 30 can be used to electrically insulate the pole 50 from the end wall 111.

[0038] The pole 50 can further include an outer flange 53 located outside the case 200 and a main body 51 passing through the first assembly hole 118 and the second assembly hole 119. The main body 51 can be a portion of the pole 50 located in the first assembly hole 118 in the axial direction of the first assembly hole 118. The outer flange 53 of the pole 50 is connected to one end of the main body 51 located outside the case 200, and the inner flange 52 is connected to one end of the main body 51 located inside the case 200. The inner flange 52 and the outer flange 53 can each extend radially beyond the first assembly hole 118.

[0039] Figure 4 As shown,Figure 3 A local enlarged view of the region Ap in FIG. 8B. Referring to FIG. 8B, Figure 3 and Figure 4 As shown in FIG. 8B, the inner flange 52 is pressed against the lower plastic 30 by riveting, and the edge of the inner flange 52 is at least partially pressed into the interior of the lower plastic 30. In the axial direction, the depth of the inner flange 52 pressed into the interior of the lower plastic 30 is A, i.e. the maximum distance of the inner flange 52 from the surface 30a of the lower plastic 30 in the axial direction towards the end wall 111. In the above embodiment of the application, since the edge of the inner flange 52 is at least partially pressed into the lower plastic 30, the riveting strength of the pole can be improved.

[0040] The inner flange 52 has a first surface 52a extending radially beyond the edge of the first assembly hole 118 and facing the end wall 111, and at least part of the first surface 52a extends upwards towards the end wall 111 away from the edge of the first assembly hole 118, so that the edge of the inner flange 52 is at least partially pressed into the lower plastic 30. In this embodiment, at least part of the first surface 52a is arc-shaped. The first surface 52a of the inner flange 52 can be considered as concave towards the interior of the housing, and the outer end of the first surface 52a can be more easily pressed into the lower plastic 30.

[0041] The inner flange 52 can further include a second surface 52b facing away from the end wall 111. The second surface 52b can include an arc shape. The second surface 52b extends upwards towards the end wall 111 away from the edge of the first assembly hole 118. The first surface 52a and the second surface 52b meet at the end of the inner flange 52 close to the end wall 111, forming an end 52e of the inner flange 52 pressed into the lower plastic 30. The end 52e can be the farthest end of the inner flange 52 away from the edge of the first assembly hole 118.

[0042] In some embodiments, the depth A of the inner flange 52 pressed into the interior of the lower plastic 30 satisfies: 0.02mm≤A≤0.2mm. If the maximum depth A is less than 0.02mm, the riveting strength cannot be improved. If the maximum depth A is greater than 0.2mm, the lower plastic 30 can be broken due to excessive pressure, affecting its insulation effect. The range of 0.02mm-0.2mm of the maximum depth A can improve the riveting strength, improve the strength of the pole, and ensure the insulation performance of the lower plastic 30. In some preferred embodiments, the maximum depth A satisfies: 0.05mm≤A≤0.1mm.

[0043] Further, in a plane perpendicular to the radial direction and passing through the center of the first assembly hole 118, i.e. the plane P, the edge of the inner flange 52 is at least partially pressed into the lower plastic 30. Figure 3 and Figure 4The first maximum depth Al and the second maximum depth A2 can differ by less than 0.05 mm. The difference of less than 0.05 mm ensures the dimensional consistency of the inner flange 52 pressed into the lower plastic 30 on the diametrically opposite sides, and ensures the concentricity between the overall pole post 50 and the housing 200, ensures the surface on the outer side of the pole post 50 and the end wall 111 of the housing 200 are parallel, and improves the welding yield during subsequent battery pack assembly.

[0044] The inner flange 52 has a width W in the radial direction, which is the distance from the outermost end (i.e., the end 52e) of the inner flange 52 to the edge of the first assembly hole 118. In some embodiments, 0.8 mm≤W≤3 mm. If the width W of the inner flange 52 is less than 0.8 mm, the required riveting strength cannot be provided. If the width W of the inner flange 52 is greater than 3 mm, the cantilever of the inner flange 52 is relatively long, and when the gas pressure inside the housing 200 increases, the inner flange 52 will have an outward thrust on the pole post 50. The longer the cantilever of the inner flange 52, the greater the bending moment it will bear, and the more likely the inner flange 52 will bend and deform, resulting in riveting failure. The range of 0.8 mm-3 mm for the width W can provide the desired riveting strength and pole post strength, and is easy to assemble. In some preferred embodiments, the width W of the inner flange 52 satisfies: 1.0 mm≤W≤1.8 mm.

[0045] The width W can include a first width Wl and a second width W2 on diametrically opposite sides of the pole post 50. In some embodiments, the first width Wl and the second width W2 differ by less than 0.3 mm. The difference of less than 0.3 mm ensures the dimensional consistency of the width of the inner flange 52 on diametrically opposite sides, to further improve the riveting strength, improve the pole post strength, and also ensure that the surface on the outer side of the pole post 50 remains parallel to the end wall 111 of the housing 200 after the pole post is riveted.

[0046] In the axial direction, the inner flange 52 can have different thicknesses at different positions, with the maximum thickness of the inner flange 52 being B. In some embodiments, the maximum thickness B satisfies: 0.6 mm≤B≤1.5 mm. If the maximum thickness B of the inner flange 52 is less than 0.6 mm, the structural strength of the inner flange 52 can be insufficient, and it can be difficult to ensure that the desired maximum depth A is achieved. If the maximum thickness B of the inner flange 52 is greater than 1.5 mm, it can disadvantageously occupy too much internal height space of the housing. The range of 0.6 mm-1.5 mm for the maximum thickness B of the inner flange 52 can provide sufficient structural strength, and can avoid occupying too much internal height space of the housing. In some preferred embodiments, the maximum thickness B of the inner flange 52 satisfies: 0.8 mm≤B≤1.1 mm.

[0047] The maximum thickness B of the inner flange 52 includes a first maximum thickness B1 and a second maximum thickness B2 on opposite sides of the pole 50 in the radial direction. In some embodiments, the difference between the first maximum thickness B1 and the second maximum thickness B2 is less than 0.1 mm. The difference of less than 0.1 mm ensures the dimensional consistency of the maximum thickness of the inner flange 52 on opposite sides in the radial direction, which can further improve the riveting strength and the pole strength, and also ensures that the surface on the outside of the pole 50 remains parallel to the end wall 111 of the case 200 after the pole is riveted.

[0048] In addition, the lower plastic 30 is also arranged in the first assembly hole 118 and between the pole 50 and the end wall 111 in the radial direction. The lower plastic 30 has an end face 30e located in the first assembly hole 118 and facing away from the inner flange 52. In the axial direction, the end face 30e of the lower plastic 30 is farther away from the inner flange 52 than the outer surface 111b of the end wall 111. The distance between the end face 30e of the lower plastic 30 and the outer surface 111b of the end wall 111 is D. In some embodiments, 0.03≤D≤0.3 mm. The range of the distance D can ensure good insulation of the lower plastic 30 while avoiding the end face 30e of the lower plastic 30 exceeding the outer surface 111b of the end wall 111 within the manufacturing process error range. In some preferred embodiments, the distance D satisfies: 0.05≤D≤0.1 mm.

[0049] The distance D can include a first distance D1 and a second distance D2 on opposite sides of the pole 50 in the radial direction, and the difference between the first distance D1 and the second distance D2 is less than 0.05 mm. The difference of less than 0.05 mm ensures the dimensional consistency of the distance D on opposite sides in the radial direction, which can improve the riveting strength and also ensures that the surface on the outside of the pole 50 remains parallel to the end wall 111 of the case 200 after the pole is riveted.

[0050] The secondary battery 100 can also include a sealing insulating member 70 located between the outer surface 111b of the end wall 111 and the outer flange 53 of the pole 50. The sealing insulating member 70 can also surround part of the side surface of the outer flange 53. In the axial direction of the first assembly hole 118, the sealing insulating member 70 has a thickness C between the outer surface 111b of the end wall 111 and the pole 50.

[0051] In some embodiments, the thickness C of the sealing insulating member 70 satisfies: 0.4 mm≤C≤1.0 mm. If the thickness C of the sealing insulating member 70 is less than 0.4 mm, reliable insulation cannot be ensured. If the thickness C is greater than 1.0 mm, it can disadvantageously occupy too much internal height space of the case. The range of 0.4 mm-1.0 mm of the thickness C can provide reliable insulation and can avoid occupying too much internal height space of the case. In some preferred embodiments, the thickness C of the sealing insulating member 70 satisfies: 0.5 mm≤C≤0.8 mm.

[0052] The thickness C of the sealing insulation piece 70 can include a first thickness C1 and a second thickness C2 on opposite sides of the pole 50 in the radial direction. In some embodiments, the difference between the first thickness C1 and the second thickness C2 is less than or equal to 0.05 mm. A difference of less than 0.05 mm can ensure uniformity of the overall sealing effect, preventing the compression rate of the sealing insulation piece 70 in some areas to be low and the compression rate of the sealing insulation piece 70 in some areas to be high, resulting in a risk of liquid leakage at the location with a low compression rate. In addition, a difference of less than 0.05 mm can also ensure that the surface outside the pole 50 remains parallel to the end wall 111 of the shell 200 after the pole is riveted.

[0053] The main body part 51 of the pole 50 can include a welding surface 51s facing the inside of the shell. In some embodiments, the welding surface 51s can be used for welding with the current collector plate. The welding surface 51s is concave relative to the inner flange 52 in the axial direction of the first assembly hole 118 and is concave beyond the surface 30a of the back end wall 111 of the lower plastic 30, that is, the welding surface 51s is higher than the surface 30a of the lower plastic 30 in the height direction of the secondary battery. This is because, when riveting, the inner flange 52 as a whole will be turned up to form a hook shape as shown in Figure 4 If the welding surface 51s is lower than the surface 30a of the lower plastic 30 in the case where the size of the inner flange does not change, there will be a gap between the lower position of the first surface 52a of the inner flange 52 and the lower plastic 30, resulting in an inability to guarantee the riveting strength.

[0054] As shown in Figure 5 The maximum distance H by which the welding surface 51s exceeds the lower plastic 30 in contact with the inner flange 52. In some embodiments, 0.02 mm≤H≤0.2 mm. If H is greater than 0.2 mm, it means that the moment arm between the edge of the inner flange 52 and the welding surface 51s becomes longer, and in the case where the edge of the inner flange 52 is pressed into the lower plastic 30, it is more likely to cause the inner flange 52 to bend and deform. If H is less than 0.02 mm, it can also result in an inability to guarantee the riveting strength. In some preferred embodiments, 0.05 mm≤H≤0.1 mm.

[0055] Embodiments of the present application also provide a battery pack 1002 including any one of the secondary batteries 100 described above, and the battery pack 1002 can have the beneficial effects described above with respect to the secondary battery 100.

[0056] Embodiments of the present application also provide an electronic device 1000 including the battery pack 1002 described above, and the electronic device 1000 can have the beneficial effects described above with respect to the secondary battery 100 and / or the battery pack 1002.

[0057] The following embodiments are described for the convenience of illustration, taking the electronic device 1000 as an example of a vehicle. Referring to Figure 6 The vehicle is provided with a battery pack 1002, which can be arranged at the bottom, head or tail of the vehicle body. The battery pack 1002 can be used for power supply of the vehicle, for example, the battery pack 1002 can be used as the operating power supply of the vehicle. The working part of the electronic device 1000 is electrically connected with the battery pack 1002 to obtain electrical energy support. The vehicle can be a fuel car, a gas car or a new energy car, and the new energy car can be a pure electric car, a hybrid car or an extended range car, but is not limited thereto. The working part is the vehicle body, the battery pack 1002 is arranged at the bottom of the vehicle body, and provides electrical energy support for driving of the vehicle or operation of electrical elements in the vehicle. However, in some other embodiments, the electronic device 1000 can also be a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy and an electric tool, etc. The spacecraft includes an airplane, a rocket, a space shuttle and a spacecraft, etc. The working part can obtain electrical energy from the battery pack 1002, and make corresponding working unit parts, such as a fan blade rotating unit, a dust suction working unit of a dust collector, etc. The electric toy includes a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy and an electric plane toy, etc. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator and an electric planer, etc. The embodiments of the present application do not specially limit the above-mentioned electronic device 1000.

[0058] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can be variously changed and modified. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A secondary battery characterized by comprising: Comprising: a case including an end wall and a side wall surrounding the end wall, the end wall having a first fitting hole; a lower plastic disposed on an inner surface side of the end wall facing an inside of the case, the lower plastic having a second fitting hole corresponding to the first fitting hole; a pole post passing through the first fitting hole and the second fitting hole, the pole post including an inner flange located on a side of the lower plastic facing away from the end wall and clamping the lower plastic together with the end wall; wherein, along a radial direction of the case, the inner flange presses the lower plastic by riveting, and an edge of the inner flange is at least partially pressed into an inside of the lower plastic. 2.The secondary battery of claim 1, wherein: the inner flange has a first surface extending beyond an edge of the first fitting hole along the radial direction and facing the end wall, at least a portion of the first surface extending toward the end wall as it moves away from the edge of the first fitting hole. 3.The secondary battery of claim 1, wherein: along an axial direction of the first fitting hole, a depth at which the inner flange is pressed into the inside of the lower plastic is A, where 0.02 mm≤A≤0.2 mm. 4.The secondary battery of claim 3, wherein: in a plane perpendicular to the radial direction and passing through a center of the first fitting hole, the depth A includes a first maximum depth A1 and a second maximum depth A2 on opposite sides of the pole post along the radial direction, a difference between the first maximum depth A1 and the second maximum depth A2 being less than 0.05 mm. 5.The secondary battery of claim 1, wherein: the inner flange has a width W along the radial direction, the width W being a distance from an outermost end of the inner flange to an edge of the first fitting hole, where 0.8 mm≤W≤3 mm. 6.The secondary battery of claim 5, wherein: in a plane perpendicular to the radial direction and passing through a center of the first fitting hole, the width W includes a first width W1 and a second width W2 on opposite sides of the pole post along the radial direction, a difference between the first width W1 and the second width W2 being less than 0.3 mm. 7.The secondary battery of claim 1, wherein: along the axial direction of the first fitting hole, the inner flange has a maximum thickness B, where 0.6 mm≤B≤1.5 mm. 8.The secondary battery of claim 7, wherein: in a plane perpendicular to the radial direction and passing through a center of the first fitting hole, the maximum thickness B includes a first maximum thickness B1 and a second maximum thickness B2 on opposite sides of the pole post along the radial direction, a difference between the first maximum thickness B1 and the second maximum thickness B2 being less than 0.1 mm. 9.The secondary battery of claim 1, wherein: the pole post further includes an outer flange located on an outside of the case, wherein the secondary battery further comprises: A sealing and insulating member is located between an outer surface of the end wall facing an outside of the case and the outer flange of the pole, wherein the sealing and insulating member has a thickness C between the outer surface of the end wall and the pole in an axial direction of the first assembly hole, 0.4 mm ≤ C ≤ 1.0 mm. 10.The secondary battery according to claim 9, wherein In a plane perpendicular to the radial direction and passing through the center of the first assembly hole, the thickness C includes a first thickness C1 and a second thickness C2 on opposite sides of the pole in the radial direction, and a difference between the first thickness C1 and the second thickness C2 is less than or equal to 0.05 mm. 11.The secondary battery according to claim 1, wherein The lower plastic is further disposed in the first assembly hole and between the pole and the end wall in the radial direction, and the lower plastic has an end surface in the first assembly hole and facing away from the inner flange, In the axial direction of the first assembly hole, the end surface of the lower plastic is farther away from the inner flange than an outer surface of the end wall, and a distance between the end surface and the outer surface is D, wherein 0.03 ≤ D ≤ 0.3 mm. 12.The secondary battery according to claim 11, wherein In a plane perpendicular to the radial direction and passing through the center of the first assembly hole, the distance D includes a first distance D1 and a second distance D2 on opposite sides of the pole in the radial direction, and a difference between the first distance D1 and the second distance D2 is less than 0.05 mm. 13.The secondary battery according to claim 1, wherein The pole further includes a main body portion connected to the inner flange, the main body portion passing through the first assembly hole and the second assembly hole, the main body portion including a welding surface facing the inside of the case, the welding surface being concave relative to the inner flange in the axial direction of the first assembly hole beyond a surface of the lower plastic facing away from the end wall, The welding surface beyond the lower plastic in contact with the inner flange has a maximum distance H, wherein 0.02 mm ≤ H ≤ 0.2 mm.

14. A battery pack, characterized by A secondary battery according to any one of claims 1 to 13.

15. An electronic device, comprising: A battery pack according to claim 14.

Images