Cylindrical shell, cylindrical battery and battery module

Abstract

The invention relates to the field of batteries, and discloses a cylindrical shell, a cylindrical battery and a battery module. The cylindrical shell is an aluminum metal shell or an aluminum alloy shell and comprises end plates and side plates. A transition part is arranged between the end plate and the side plate and comprises an arc-shaped section. The ratio of the size of the transition part in the axial direction of the cylindrical shell to the size of the transition part in the radial direction of the bottom plate is L; the radius of the arc-shaped section is R, the Brinell hardness of the shell is H, and the relation among R, H and L meets the condition that H * L-1 / R is larger than or equal to 0 and smaller than or equal to 28. The cylindrical shell is more beneficial to the arrangement of the insulating layer.

Description

Technical Field

[0001] This application relates to the technical field of batteries, and particularly to a cylindrical shell, a cylindrical battery, and a battery module. Background Art

[0002] The housing of a battery is generally a metal housing, and end plates, such as the bottom plate and side plates, are usually integrally formed structures. The existing processing technology is the stretching process. Limited by the existing processing technology, there are usually obvious edges at the transition between the side plates and the bottom plate of the housing, as Figure 1 shown. Since an insulating layer needs to be provided on the outer surface of the battery, due to the existence of the edges, it is easy to cause the problem of insulating layer failure, reducing the insulation performance of the housing, and further affecting the performance and life of the battery. Summary of the Invention

[0003] This application discloses a cylindrical shell, a cylindrical battery, and a battery module, which are used to solve the problem of uneven thickness of the insulating coating at the side plates and end plates of the housing.

[0004] To achieve the above object, this application provides the following technical solutions: In a first aspect, this application provides a cylindrical shell, which is an aluminum metal shell or an aluminum alloy shell, including an end plate and side plates. The end plate is a circular end plate, and the side plates are arranged along the circumference of the end plate and extend along the axial direction of the cylindrical shell; A transition part is provided between the end plate and the side plates. The transition part includes an arc segment; the ratio of the dimension of the transition part along the axial direction of the cylindrical shell to the dimension of the transition part along the radial direction of the end plate is L; The radius of the arc segment is R, and the Brinell hardness of the shell is H. The relationship among R, H, and L satisfies 0 ≤ H * |L - 1| / R ≤ 28; where the unit of R is mm and the unit of H is HB.

[0005] In a second aspect, this application provides a cylindrical battery, including an electric core and the cylindrical shell of this application, and the electric core is placed inside the cylindrical shell.

[0006] In a third aspect, this application provides a battery module, which includes a plurality of cylindrical batteries of the first aspect of this application.

[0007] Adopting the technical solutions of this application, the beneficial effects are as follows: For the cylindrical shell of the present application, a transition part with an arc section is provided between the side plate and the end plate, and the relationship among the radius R of the arc section, the Brinell hardness H of the shell, and L satisfies that H*|L - 1| / R is within the range of 0 - 28. For the cylindrical shell with this structure, since the transition part of the arc section is smoother, when setting the insulating layer, the occurrence of insulating layer failure problems can be reduced, thereby improving the safety of the battery.

[0008] By comprehensively controlling the relationship among the ratio L, the radius R of the arc section, and the hardness H of the shell, the shell forming is improved, facilitating the formation of a uniformly transitional arc section between the side plate and the end plate, which is beneficial to the formation of the insulating layer and at the same time avoids interference between the battery cell and the shell when the battery cell enters the shell. If the value of H*|L - 1| / R is too large, the shell hardness is high, and / or the radius R of the arc section is too small, and / or the absolute value of L - 1 is relatively large, it is not conducive to forming a uniformly transitional arc section, resulting in an increased risk of failure during the formation of the insulating layer. If the value of H*|L - 1| / R is too small, the hardness is low, or the absolute value of L - 1 is relatively small, and / or the radius R of the transition section is too large, the risk of interference increases when the battery cell enters the shell.

[0009] For the cylindrical battery of the present application, since it includes the cylindrical shell of the present application, when the cylindrical battery of the present application has the above parameter characteristics, an insulating layer with fewer defects can be obtained, thereby improving the insulation of the cylindrical battery and further improving the safety of the cylindrical battery.

[0010] For the battery module of the present application, since it includes the cylindrical battery of the present application, when the cylindrical battery of the present application has the above parameter characteristics, an insulating layer with fewer defects can be obtained, thereby improving the insulation between multiple cylindrical batteries in the battery module and further improving the safety of the battery module. Description of the Drawings

[0011] Figure 1 It is a partial structural schematic diagram of the radial section of an existing shell; Figure 2 It is a partial structural schematic diagram of the radial section of a cylindrical battery according to an embodiment of the present application; Figure 3 It is a partial structural schematic diagram of the radial section of a shell according to an embodiment of the present application; Figure 4 It is a partial structural schematic diagram of the bottom of a cylindrical battery of an embodiment.

[0012] Reference Numerals in the Drawings: 10 - cylindrical shell; 11 - side plate; 12 - bottom plate; 120 - liquid injection hole; 121 - convex part; 13 - transition part; 130 - arc section; 14 - insulating plate; 20 - battery cell. Detailed Embodiments

[0013] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0014] The housing of an existing battery is usually formed by a stretching process. For a cylindrical battery, its housing is usually formed by a stretching process into a hollow cylindrical housing with a cylindrical structure. The battery cell is placed inside the housing and encapsulated by the housing. Among them, in a cylindrical battery, the housing is a cylindrical housing, and its material is metal, such as aluminum, aluminum alloy (such as aluminum-magnesium alloy or aluminum-manganese alloy, etc.). To ensure the insulation of the cylindrical battery, an insulating layer is usually provided on the outer surface of the cylindrical housing, such as spraying an insulating coating or covering an insulating film, etc. Among them, the insulating coating can be, for example, a polyethylene (PE) coating, a polyurethane (PU) coating, an epoxy (EP) coating, a potassium silicate coating, a silicone coating, etc. The insulating coating can be formed on the outer surface of the cylindrical housing by spraying, coating, electrophoresis or other methods. The insulating film can be, for example, a polypropylene (PP) insulating film, a PE insulating film, etc.

[0015] Figure 1 FIG. is a partial structural schematic diagram of a radial section of an existing cylindrical housing. As Figure 1 shown, due to the limitations of the processing technology, there is a flat area in the transition part 13 between the side plate 11 and the bottom plate 12 of the existing cylindrical housing 10, thus forming an edge between the side plate 11 and the bottom plate 12. The existence of this edge will affect the setting of the insulating layer, and further affect the insulation performance of the battery.

[0016] Taking the insulating coating as an example of the insulating layer, when the insulating coating is formed by spraying, the existence of this edge will cause uneven thickness of the insulating coating formed by spraying, and the absence of the insulating coating on the surface of some transition parts, etc., thus affecting the insulation performance of the battery.

[0017] Based on this, the present application provides a cylindrical battery. Figure 2 FIG. is a structural schematic diagram of a radial section of a cylindrical battery according to an embodiment of the present application. As Figure 2As shown, the cylindrical battery includes a cylindrical housing 10 and an electric core 20 disposed within the cylindrical housing 10. The cylindrical housing 10 is used to encapsulate the electric core 20. Among them, the cylindrical housing 10 includes an end plate, a side plate 11, and a transition portion 13 disposed between the end plate and the side plate 11. The end plate may include a top plate and a bottom plate. The top plate and the bottom plate are respectively disposed at both ends of the side plate along the axial direction of the cylindrical housing. Along the axial direction of the cylindrical housing, the end plate at the top is the top plate, and the end plate at the bottom is the bottom plate. Hereinafter, the bottom plate will be taken as an example for illustration. It can be understood that it is also feasible to replace the bottom plate with the top plate in the following listed structures. That is, in the following embodiments of the present application, the transition portion 13 between the bottom plate 12 and the side plate 11.

[0018] Referring to Figure 2 , in the radial section of the cylindrical housing, the transition portion 13 between the bottom plate 12 and the side plate 11 includes an arc segment 130. The dimension of the transition portion 13 along the axial direction of the side plate 11 is h1, and the dimension of the transition portion 13 along the radial direction of the bottom plate 12 is h2. Among them, as Figure 2 shown, h1 is the distance from the intersection point of the transition portion 13 and the side plate 11 to the extension line of the bottom plate 12. h2 is Figure 2 the distance from the intersection point of the transition portion 13 and the bottom plate 12 in

[0019] to the extension line of the side plate 11. When measuring, the bottom plate of the cylindrical housing can be placed flat on the test bench. The vertical distance from the connection point of the side plate and the transition portion to the bottom plate is h1, and the vertical distance from the connection point of the bottom plate and the transition portion along the radial direction of the bottom plate to the side plate is h2. Among them, the ratio L of h1 to h2 is 0.6 - 1.4.

[0020] The cylindrical housing in the embodiment of the present application can be formed by a cold extrusion process. The bottom plate and the side plate are integrally formed by the cold extrusion process, which can improve the shape of the transition portion between the side plate and the bottom plate. By setting a transition portion with an arc segment, the fitting degree between the insulating layer and the cylindrical housing can be improved, and the occurrence of insulation failure problems can be reduced. In one embodiment, referring to Figure 2 , in the radial section of the cylindrical housing 10, the arc segment 130 of the transition portion 13 can be a circular arc. The circular arc design is more conducive to the flow of the spraying liquid and reduces the flow resistance.

[0021] Taking the insulating coating formed by spraying as an example. By providing a transition portion with an arc segment, the flow direction of the spraying liquid in the spraying process can be improved, enabling the spraying liquid to uniformly flow from the side plate towards the bottom plate. Among them, if the ratio L of the dimensions h1 and h2 of the transition segment is too small, it is easy to form an insulating coating with uneven thickness during spraying. If the ratio L of h1 and h2 is too large, interference is likely to occur between the battery cell and the cylindrical housing, increasing the difficulty of assembling the battery cell and reducing the placement space for the battery cell, which is not conducive to increasing the capacity of the cylindrical battery. Controlling the ratio of h1 to h2 within the range of 0.6 - 1.4 can increase the fluidity of the spraying liquid during the spraying process and the resistance when the spraying liquid flows through the arc-shaped transition portion, reducing the problem of uneven spraying thickness during the spraying process.

[0022] Taking the insulating film as an example, during the wrapping process, the insulating film has a higher degree of fit with the transition portion, which can reduce the void area between the insulating film and the transition portion. Among them, in addition to the arc segment that the transition portion can include, in some other embodiments, it can also include a small straight segment. The transition portion can be connected to the side plate or the bottom plate by welding the small straight segment. In one embodiment, the transition portion only includes an arc segment.

[0023] In the embodiments of the present application, the dimensions of h1 and h2 can be adjusted by adjusting the dimensions of the extrusion die of the cylindrical housing. The ratio L of h1 to h2 can be 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, or 1.4, etc., or any value between any two of the above values.

[0024] For the cylindrical housing in the embodiments of the present application, the relationship among the R, the H, and the L satisfies 0 ≤ H * |L - 1| / R ≤ 28, such as 0 < H * |L - 1| / R ≤ 28, or 0.5 ≤ H * |L - 1| / R ≤ 28. Among them, the unit of R is mm, and the unit of H is HB. By comprehensively controlling the relationship among the hardness of the cylindrical housing, the ratio L of h1 to h2, and the radius R of the arc segment, the forming of the cylindrical housing is improved, facilitating the formation of a uniformly transitioning transition portion between the side plate and the bottom plate, being conducive to the uniform coating of the insulating coating and the wrapping of the insulating film, and also avoiding interference between the battery cell and the cylindrical housing when the battery cell is inserted into the housing. In a preferred embodiment, the relationship H * |L - 1| / R among the R, the H, and the L satisfies: 0 ≤ H * |L - 1| / R ≤ 20, further 0.5 ≤ H * |L - 1| / R ≤ 20, and further 0.5 ≤ H * |L - 1| / R ≤ 15. By optimizing the relationship among R, L, and H, the setting effect of the insulating layer can be further improved, such as the spraying effect of the insulating coating.

[0025] Exemplarily, the value of H * |L - 1| / R can be, for example, 0, 1, 2, 4, 5, 8, 10, 12, 15, 18, 20, 22, 25, or 28, or any value between any two of the above values.

[0026] Continue to refer to Figure 2 In one embodiment, after the battery cell 20 is inserted into the cylindrical housing 10, the edge of the battery cell 20 can contact the transition portion 13. If the area of the transition portion 13 used to support the battery cell 20 is too small, when the battery cell 20 shakes and tilts, the bottom electrode sheet is extremely likely to be damaged by pressing.

[0027] In one embodiment, the value range of h1 can be 0.5 - 4 mm, preferably 1 - 3 mm. By controlling the range of h1, it is possible to avoid the situation where h1 is too small and the insulation protection effect of the insulating layer is poor, and it is also possible to avoid the situation where h1 is too large and interference occurs between the battery cell and the cylindrical housing when the battery cell is inserted into the housing.

[0028] Exemplarily, the value of h1 can be, for example, 0.5 mm, 0.6 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3.0 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm, 4.0 mm, etc., or any value between any two of the above values.

[0029] In one embodiment, the value range of h2 is 0.5 - 4 mm, preferably 1 - 3 mm. If the size of h2 is too small, it is not sufficient to ensure that enough support surface is reserved for the battery cell, which is likely to cause uneven stress on the battery cell. If the size of h2 is too large, during spraying, when the spraying liquid flows, it is not easy to flow to the junction of the arc-shaped transition portion and the bottom plate, resulting in a decrease in the quality of the sprayed insulating coating.

[0030] Exemplarily, the value of h2 can be, for example, 0.5 mm, 0.6 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3.0 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm, 4.0 mm, etc., or any value between any two of the above values.

[0031] In one embodiment, h1 can be less than h2 to reduce the risk of insertion into the housing during the battery assembly process.

[0032] In one embodiment, the radius R of the arc segment ranges from 1 to 4 mm. For the insulating coating formed by spraying, if the radius R of the arc segment is too small, sagging is likely to occur during spraying, resulting in an unevenly thick insulating coating formed by spraying. This increases the risk of insulation failure of the battery. However, the radius R of the arc segment cannot be too large, as this will cause interference between the cylindrical housing and the battery cell, and can also easily cause uneven stress on the battery cell placed inside the cylindrical housing. Exemplarily, the value of R can be, for example, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3.0 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm, 4.0 mm or any value between the above two values.

[0033] In the embodiment of the present application, the radius of the arc segment in the transition portion can be measured by the three-point method. By uniformly taking three points on the arc portion, the radius of the corresponding circle determined is the radius of the arc segment.

[0034] The value of H ranges from 20 to 80 HB, preferably 30 to 70 HB. If the hardness of the cylindrical housing is too high, it is difficult to form a transition portion with a uniform transition during the molding of the cylindrical housing, thereby increasing the risk of sagging during spraying. The hardness of the cylindrical housing cannot be too low either, as the risk of the cylindrical housing resisting the expansion of the battery cell is weak later.

[0035] Exemplarily, the value of H can be, for example, 20 HB, 25 HB, 30 HB, 35 HB, 40 HB, 45 HB, 50 HB, 55 HB, 60 HB, 65 HB, 70 HB, 75 HB, 80 HB or a value between any two of the above values.

[0036] Among them, the measurement method of the Brinell hardness of the cylindrical housing can refer to HBW 2.5 / 62.5 in GB / T 231.1-2018. Among them, the Brinell hardness of the cylindrical housing can be adjusted by adjusting the contents of manganese and magnesium in the composition and the parameters during the heat treatment process of the material.

[0037] The ratio of the minimum thickness to the maximum thickness of the transition portion is less than or equal to 0.8, preferably 0.3 to 0.8. Exemplarily, the ratio of the two can be, for example, 0.3, 0.4, 0.5, 0.6, 0.7, or 0.8 or a value between any two of the above values.

[0038] Generally, the thickness of the side plate of the battery is less than the thickness of the bottom plate. From the side plate to the bottom plate, the thickness of the transition portion may change. The thickness of the part of the transition portion close to the side plate may be less than the part close to the bottom plate. If the ratio of the minimum thickness to the maximum thickness of the transition portion is too small, the side plate is likely to crack during the molding of the cylindrical housing.

[0039] In one embodiment, asFigure 2 As shown, in the axial direction of the cylindrical shell, the height h1 of the transition part and the height H of the cylindrical shell 1 The ratio is 0.005 - 0.04. Exemplarily, the above ratio can be 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04 or any value between any two of the above values.

[0040] The ratio of the height h1 of the transition part to the height of the cylindrical shell cannot be too large. If this ratio is too large, the transition part is relatively long, and there is a high risk of interference between the battery cell and the cylindrical shell when the battery cell enters the shell. If the above ratio is too small, it is difficult to form the cylindrical shell, and the risk of forming edges increases. In addition, if the above ratio is too small, the difficulty of setting the insulating layer increases, and insulation failure is likely to occur.

[0041] In one embodiment, the dimension h2 of the transition part in the radial direction of the bottom plate and the diameter H of the cylindrical shell 2 The ratio is 0.01 - 0.12. This ratio cannot be too small, otherwise the size of the transition part is too small, which is not conducive to the setting of the insulating layer and the risk of insulation failure increases. The above ratio cannot be too large, otherwise the supporting effect of the bottom plate is poor. Exemplarily, the ratio of the dimension of the transition part in the radial direction of the bottom plate to the diameter of the bottom plate can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12 or any value between any two of the above values.

[0042] Figure 3 It is a partial structural schematic diagram of the radial section of a cylindrical shell according to an embodiment of the present application. As Figure 3 shown, in one embodiment, in the radial section of the cylindrical shell 10, at the intersection of the side plate 11 and the transition part 13, the included angle a1 between the tangent of the transition part 13 and the extension line of the side plate 11 is less than greater than 0° and less than or equal to 50°. Among them, the a1 angle can be measured by a microscope.

[0043] When the included angle a1 is less than 50°, the occurrence of the problem of paint dripping can be reduced, and the paint is more likely to flow along the surface of the arc-shaped transition part towards the bottom plate.

[0044] In one embodiment, the thickness of the side plate is 0.2 - 0.6 mm. The thickness of the bottom plate is 0.5 - 1.2 mm.

[0045] The cylindrical shell is an aluminum alloy shell, and the composition of the aluminum alloy shell includes manganese element and / or magnesium element; the mass ratio of the manganese element in the total composition of the aluminum alloy shell is 0.5-2%; the mass ratio of the magnesium element in the total composition of the aluminum alloy shell is greater than 0 and less than or equal to 0.5%. Manganese and magnesium in the above contents can help improve the forming performance of the shell.

[0046] Among them, the element composition and content test of the cylindrical shell can be measured by referring to the spectral analysis method specified in GB / T 7999-2007.

[0047] Refer to Figure 2 , the battery cell 20 of the embodiment of the present application is placed in the cylindrical shell 10 and encapsulated by the cylindrical shell 10. In one embodiment, a liquid injection hole 120 may be provided in the middle of the bottom plate 12. In other embodiments, the liquid injection hole 120 may not be provided in the middle.

[0048] The battery cell 20 in the present application may be a wound core. The winding hole of the wound core may be arranged corresponding to the liquid injection hole 120. The battery cell 20 includes a positive electrode sheet, a separator, and a negative electrode sheet, and the positive electrode sheet, the separator, and the negative electrode sheet are wound.

[0049] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, and the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. There is no particular limitation on the positive electrode current collector as long as it has conductivity and does not cause adverse chemical changes in the battery. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or aluminum or stainless steel surface-treated with one of carbon, nickel, titanium, silver, etc. can be used. The negative electrode current collector can be made of copper, stainless steel, nickel, titanium, etc. In a specific embodiment, aluminum can be used for the positive electrode and copper can be used for the negative electrode. The positive electrode active material layer includes a positive electrode active material, and the positive electrode active material includes nickel cobalt manganese ternary material, lithium iron phosphate material, lithium manganese iron phosphate material, etc.; the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material includes artificial graphite, natural graphite, silicon-based material, etc.

[0050] The separator is located between the positive electrode sheet and the negative electrode sheet and is used to separate the positive electrode sheet and the negative electrode sheet to prevent the positive electrode sheet and the negative electrode sheet from contacting and short-circuiting. The separator can be various materials suitable for the separator of electrochemical energy storage devices in the art. Specifically, the separator includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, and natural fiber.

[0051] Among them, the battery cell includes a battery cell body, a positive tab and a negative tab led out from the battery cell body. The positive tab is connected to the positive electrode plate of the battery cell body, and the negative tab is connected to the negative electrode plate of the battery cell body. The cylindrical shell includes a terminal assembly, and one of the positive tab and the negative tab is electrically connected to the terminal assembly, and the other is electrically connected to the cylindrical shell.

[0052] The tab (positive tab or negative tab) can be formed by cutting the current collector of the electrode plate (positive electrode plate or negative electrode plate), or can be a separate conductive part. The tab is used to realize the transmission of current inside the battery cell. The material of the tab can be the same as that of the current collector, such as it can be selected from aluminum, copper, etc. Exemplarily, the positive tab and the positive current collector can be aluminum, and the negative tab and the negative current collector can be copper.

[0053] The cylindrical battery includes a terminal assembly, and the terminal assembly is used to connect to an external circuit, such as being connected to the terminal assembly through a bus bar, etc., to realize the series-parallel electrical connection of multiple batteries. The tab is electrically connected to the terminal assembly. The battery cell is a cylindrical battery cell, and the tab can be led out from both ends in the axial direction of the battery cell, or can be led out from one end in the axial direction. One of the positive tab and the negative tab can be directly electrically connected to the terminal assembly, or can be indirectly electrically connected. When indirectly electrically connected, the tab can be first electrically connected to the current collecting plate, and then the current collecting plate is electrically connected to the terminal assembly. The other of the positive tab and the negative tab can be directly electrically connected to the cylindrical shell, or can be indirectly electrically connected.

[0054] In some other embodiments, the battery cell can also be of other shapes, which is not limited.

[0055] Among them, after the battery cell is placed in the cylindrical shell, in the axial direction of the cylindrical shell, the bottom surface of the battery cell can be located above the plane where the intersection line of the side plate and the transition part is located (such as Figure 2 the horizontal plane at the AB line shown), or the bottom surface of the battery cell can also be located below the plane where the intersection line of the side plate and the transition part is located.

[0056] When the bottom surface of the battery cell is located above the plane where the intersection line of the side plate and the transition part is located, the risk is small when the battery cell is put into the shell. When the bottom surface of the battery cell is located below the plane where the intersection line of the side plate and the transition part is located, the battery cell can be made higher to increase the energy density.

[0057] In one embodiment, the edge of the orthographic projection of the battery cell on the bottom plate is located within the range of the intersection line of the bottom plate and the transition part. In this assembly structure, the stability of the battery cell is higher. In another embodiment, the edge of the orthographic projection of the battery cell on the bottom plate is located outside the range of the intersection line of the bottom plate and the transition part. In this assembly structure, the size of the battery cell can be increased, thereby increasing the energy density of the battery cell.

[0058] In one embodiment, the outer surface of the cylindrical shell is provided with an insulating coating. The thickness d1 of the insulating coating on the side plate is less than or equal to 0.2 mm. The value range of R is 1 - 4 mm, and the value range of L is 0.8 - 1.1. By optimizing the thickness of the insulating coating on the side plate, as well as the radius of the arc section and the value of L, the spraying effect of the insulating coating can be further optimized, making the thickness uniformity of the insulating coating higher.

[0059] When the outer surface of the cylindrical shell is coated with an insulating film, the thickness of the insulating film coated on the outer surface of the cylindrical shell can be 0.05 - 2 mm. The insulating film with this thickness can form a better coating effect, avoiding problems such as warping or bulging of the insulating film caused by too thin or too thick a thickness.

[0060] In one embodiment, between the battery cell and the bottom plate, the size of the separator is larger than that of the positive electrode sheet and the negative electrode sheet. In one embodiment, in the axial direction of the cylindrical shell, the bottom edges of the negative electrode sheet and the positive electrode sheet are located above the plane where the intersecting line of the side plate and the transition part is located, and the bottom edge of the separator is located below the plane where the intersecting line of the side plate and the transition part is located. In one embodiment, at the bottom of the battery cell, the size by which the separator extends beyond the negative electrode sheet is 0.5 - 3 mm. The part of the separator that extends beyond the positive and negative electrode sheets will fill the space between the battery cell and the bottom plate to improve the insulation between the battery cell and the shell.

[0061] Figure 4 It is a schematic diagram of a partial structure at the bottom of a cylindrical battery according to an embodiment. As Figure 4 shown, in one embodiment, on the side of the bottom plate 12 of the cylindrical shell 10 facing the battery cell 20, there is a convex part 121 protruding towards the battery cell 20. The liquid injection hole 120 is arranged on the convex part 121, and a part of the bottom surface of the battery cell 20 is in contact with the convex part 121. This convex part 121 can be used to support the battery cell 20. At the corresponding position of the convex part 121, the outer side of the bottom plate 12 is a groove recessed towards the battery cell 20, and this groove is used to place the plugging member of the liquid injection hole.

[0062] In one embodiment, the diameter of the liquid injection hole is greater than or equal to 2 mm, and the value range of L is 0.8 - 1.4. The larger the diameter of the liquid injection hole, the larger the area of the bottom plate it occupies. Among them, the value range of L is further limited to 0.8 - 1.4, which can avoid the assembly of the battery with other structural components due to insufficient support area of the bottom plate, such as insufficient bonding area between the battery and the box body; in addition, it can also prevent the battery cell from tilting due to collision.

[0063] In one embodiment, the core is provided with a core hole, the aperture of the core hole is greater than or equal to 4 mm, and R is 1-3 mm. The core hole can provide space for the expansion of the battery cell. The larger the aperture of the core hole, the smaller the outward expansion size of the battery cell. By further controlling the radius R of the arc segment within the range of 1-3 mm, the setting effect of the insulating layer can be improved and the insulation performance can be enhanced.

[0064] In one embodiment, with continued reference to Figure 4 , an insulating plate 14 is provided between the battery cell 20 and the bottom plate 12, and the thickness of the insulating plate 14 is 0.1-1.2 mm. Since there is a transition portion between the bottom plate and the side plate, and the edge of the battery cell may contact the transition portion. At this time, there will be a certain gap between the bottom plate and the battery cell. By providing the insulating plate 14, the gap between the battery cell and the bottom plate can be filled to prevent the battery cell from shaking. In addition, by providing the insulating plate 14, insulation between the battery cell 20 and the bottom plate 12 can be achieved, and sufficient support force can be provided for the battery cell 20. The material of the insulating plate 14 can be an organic polymer material, such as polyethylene or polypropylene, etc.

[0065] In one embodiment, the distance between the battery cell and the side plate is less than or equal to 0.8 mm, and the radius R of the arc segment is 0.5-3 mm. When the distance between the battery cell and the side plate is less than or equal to 0.8 mm, the radius of the arc segment in the transition portion needs to be controlled relatively small to provide more space for the expansion of the battery cell.

[0066] Hereinafter, the insulation performance of the cylindrical battery with the cylindrical shell of the embodiment of the present application will be tested and described in conjunction with specific embodiments and comparative examples.

[0067] Embodiments 1-8 and Comparative Examples 1-2 are respectively a kind of cylindrical shell. The specific parameters of the cylindrical shells of each embodiment and comparative example are listed in Table 1.

[0068] Table 1

[0069] An insulating coating is sprayed on the outer surface of the cylindrical shells of each embodiment and comparative example respectively. The pass rate of the thickness of the insulating coating in the transition portion among 200 samples of each embodiment and comparative example is tested. Thickness qualification requirement: The ratio of the thickness of the insulating coating in the transition portion to the thickness of the insulating coating on the side plate is greater than 0.5, and it is observed whether the pole piece drops material when the battery cell is put into the shell. The test and observation results are listed in Table 2.

[0070] Table 2

[0071] As can be seen from the data in Table 1 and Table 2, when the value of H *|L-1| / R meets the range value defined in this application, the passing rate of the insulation coating thickness of the transition part in the corresponding sample is above 90%. The passing rates of the samples corresponding to Comparative Example 1 and Comparative Example 2 are both below 70%. In addition, when the hardness of the cylindrical shell is relatively high, resulting in the value of H *|L-1| / R exceeding the range defined in this application, the electrode sheet is likely to be damaged when the battery core is inserted into the shell, causing the electrode sheet to drop off.

[0072] For the same purpose, the embodiment of this application also provides a battery module, which may include a plurality of cylindrical batteries according to the embodiments of this application. The plurality of cylindrical batteries can be connected in series or in parallel according to specific design requirements.

[0073] Obviously, those skilled in the art can make various changes and modifications to the embodiments of this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalent technologies, this application is also intended to include these changes and modifications.

Claims

1. A cylindrical shell, characterized in that: The cylindrical shell is an aluminum metal shell or an aluminum alloy shell, and comprises an end plate and a side plate, wherein the end plate is a circular end plate, and the side plate is arranged along the circumference of the end plate and extends along the axial direction of the cylindrical shell; A transition portion is provided between the end plate and the side plate, the transition portion comprising an arc segment; a ratio of a dimension of the transition portion along the axial direction of the cylindrical shell to a dimension of the transition portion along the radial direction of the end plate is L; a radius of the arc segment is R, and a Brinell hardness of the shell is H; The relationship among R, H and L satisfies 0≤H*|L-1| / R≤28; wherein the unit of R is mm, and the unit of H is HB.

2. The cylindrical housing according to claim 1, characterized in that The relationship among the R, the H and the L satisfies 0≤H*|L-1| / R≤20.

3. The cylindrical housing according to claim 1 or 2, characterized in that: The value range of R is 1-4 mm, the value range of H is 20-80 HB, and the range of L is 0.6-1.

4.

4. The cylindrical housing according to claim 1 or 2, characterized in that: The ratio of the minimum thickness to the maximum thickness of the transition portion is less than or equal to 0.8, and the value range of H is 30-70HB.

5. The cylindrical housing according to claim 1 or 2, characterized in that: In the axial direction of the cylindrical shell, the ratio of the height of the transition portion to the height of the cylindrical shell is 0.005-0.

04.

6. The cylindrical housing according to claim 1 or 2, characterized in that: The ratio of the dimension of the transition portion along the radial direction of the end plate to the diameter of the cylindrical shell is 0.01-0.

12.

7. The cylindrical housing according to claim 1 or 2, characterized in that: In the radial section of the cylindrical shell, at the intersection of the side plate and the transition portion, the angle between the tangent line of the transition portion and the extension line of the side plate is greater than 0° and less than or equal to 50°.

8. The cylindrical housing according to claim 1 or 2, characterized in that: The thickness of the side plate is 0.2-0.6 mm; the thickness of the end plate is 0.5-1.2 mm.

9. The cylindrical housing according to claim 1 or 2, characterized in that: The cylindrical shell is an aluminum alloy shell, and the components of the aluminum alloy shell include manganese and / or magnesium; The mass proportion of the manganese element in the total composition of the aluminum alloy shell is 0.5-2%; The mass proportion of the magnesium element in the total composition of the aluminum alloy shell is greater than 0 and less than or equal to 0.5%.

10. The cylindrical housing according to claim 1 or 2, characterized in that: The outer surface of the cylindrical shell is provided with an insulating coating, the thickness d1 of the insulating coating of the side plate is less than or equal to 0.2 mm, the value range of R is 1-4 mm, and the value range of L is 0.8-1.

1.

11. The cylindrical housing according to claim 1 or 2, characterized in that: The outer surface of the cylindrical shell is covered with an insulating film, and the thickness of the insulating film is 0.05-2mm.

12. The cylindrical housing according to claim 1 or 2, characterized in that: The end plate is provided with a liquid injection hole, the diameter of the liquid injection hole is greater than or equal to 2 mm, and the value range of L is 0.8-1.

4.

13. A cylindrical battery, characterized in that: It comprises a battery core and a cylindrical shell as claimed in any one of claims 1 to 12, wherein the battery core is placed in the cylindrical shell.

14. The cylindrical battery according to claim 13, characterized in that: In the axial direction of the cylindrical shell, the bottom surface of the battery core is located above the plane where the intersection line of the side plate and the transition part is located, or the bottom surface of the battery core is located below the plane where the intersection line of the side plate and the transition part is located.

15. The cylindrical battery according to claim 13 or 14, characterized in that: The orthographic projection edge of the battery cell on the end plate is located within the intersection line range of the end plate and the transition portion, or the orthographic projection edge of the battery cell on the end plate is located outside the intersection line range of the end plate and the transition portion.

16. The cylindrical battery according to claim 15, characterized in that: The end plate is provided with a protrusion facing the battery cell, and a portion of the bottom surface of the battery cell is in contact with the protrusion; The battery core is a winding core, and the winding core includes a positive electrode sheet, a separator and a negative electrode sheet which are wound together; At the bottom of the battery cell, the separator exceeds the negative electrode sheet by 0.5-3 mm.

17. The cylindrical battery according to claim 16, characterized in that: In the axial direction of the cylindrical shell, the bottom edges of the negative electrode sheet and the positive electrode sheet are located above the plane where the intersection line of the side plate and the transition part is located, and the bottom edge of the diaphragm is located below the plane where the intersection line of the side plate and the transition part is located.

18. The cylindrical battery according to claim 13 or 14, characterized in that: The battery core is a winding core, the winding core is provided with a winding core hole, the hole diameter of the winding core hole is greater than or equal to 4 mm, and the R is 1-3 mm.

19. The cylindrical battery according to claim 13 or 14, characterized in that: In the radial direction of the end plate, the distance between the battery core and the side plate is less than or equal to 0.8 mm, and the radius R of the arc segment is 0.5-3 mm.

20. The cylindrical battery according to claim 13 or 14, characterized in that: An insulating plate is provided between the battery core and the end plate, and the thickness of the insulating plate is 0.1-1.2 mm.

21. The cylindrical battery according to claim 13 or 14, characterized in that: The battery cell comprises a battery cell body and a positive electrode ear and a negative electrode ear extending from the battery cell body, wherein the positive electrode ear is connected to the positive electrode sheet of the battery cell body, and the negative electrode ear is connected to the negative electrode sheet of the battery cell body; The cylindrical shell includes a pole assembly, one of the positive electrode lug and the negative electrode lug is electrically connected to the pole assembly, and the other is electrically connected to the cylindrical shell.

22. A battery module, characterized in that: Comprising a plurality of cylindrical batteries as described in any one of claims 13-21.

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