A cylindrical shell, a cylindrical battery and a battery module

Abstract

This application relates to the field of batteries and discloses a cylindrical housing, a cylindrical battery, and a battery module. The cylindrical housing is an aluminum metal housing or an aluminum alloy housing, comprising end plates and side plates. A transition portion is provided between the end plates and the side plates, and the transition portion comprises an arcuate segment. The ratio of the transition portion along the axial direction of the cylindrical housing to the transition portion along the radial direction of the base plate is L. The radius of the arcuate segment is R, the Brinell hardness of the housing is H, and the relationship between R, H, and L satisfies 0≤H*|L‑1| / R≤28. This cylindrical housing is more conducive to the installation of an insulating layer.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a cylindrical shell, a cylindrical battery and a battery module. Background Art

[0002] The battery shell is generally a metal shell, and the end plates, such as the bottom plate and the side plates, are usually formed as a whole. The existing processing technology is a stretching process. Due to the limitations of the existing processing technology, there are usually obvious edges between the side plates and the bottom plate of the shell, such as Figure 1 Since an insulating layer needs to be provided on the outer surface of the battery, the presence of edges can easily cause the insulating layer to fail, thereby reducing the insulating performance of the shell and affecting the performance and life of the battery. Summary of the Invention

[0003] The present 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 shell.

[0004] To achieve the above objectives, this application provides the following technical solutions:

[0005] In a first aspect, the present application provides a cylindrical shell, wherein the cylindrical shell is an aluminum metal shell or an aluminum alloy shell, and includes 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;

[0006] 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;

[0007] The radius of the arc segment is R, the Brinell hardness of the shell is H, and the relationship between 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.

[0008] In a second aspect, the present application provides a cylindrical battery, comprising a battery cell and a cylindrical shell of the present application, wherein the battery cell is placed in the cylindrical shell.

[0009] In a third aspect, the present application provides a battery module, which includes multiple cylindrical batteries according to the first aspect of the present application.

[0010] The technical solution of this application has the following beneficial effects:

[0011] The cylindrical housing of the present application has a transition portion with an arc segment between its side plates and end plates. The relationship between the radius R of the arc segment and the Brinell hardness H and L of the housing satisfies the requirement that H*|L-1| / R is within the range of 0-28. This cylindrical housing structure, due to the smoother transition portion of the arc segment, can reduce the risk of insulation layer failure when installing an insulation layer, thereby improving battery safety.

[0012] By comprehensively controlling the relationship between the ratio L, the radius R of the arc segment, and the hardness H of the shell, the shell molding process is improved, facilitating the formation of a uniform arc segment transition between the side panels and end panels. This facilitates the formation of the insulation layer while preventing interference between the cell and the shell when the cell is inserted into the shell. An excessively large H*|L-1| / R value, resulting in high shell hardness, and / or an excessively small radius R of the arc segment, and / or an excessively large absolute value of L-1, can hinder the formation of a uniform arc segment transition and increase the risk of failure during insulation layer formation. An excessively small H*|L-1| / R value, resulting in low hardness, or an excessively small absolute value of L-1, and / or an excessively large radius R of the transition segment, can increase the risk of interference when the cell is inserted into the shell.

[0013] 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-mentioned 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.

[0014] The battery module of the present application includes the cylindrical battery of the present application. When the cylindrical battery of the present application has the above-mentioned parameter characteristics, an insulating layer with fewer defects can be obtained, thereby improving the insulation between multiple cylindrical batteries in the battery module, thereby improving the safety of the battery module. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the partial structure of a radial section of an existing shell;

[0016] Figure 2 This is a schematic diagram of the partial structure of a cylindrical battery under radial section according to an embodiment of the present application;

[0017] Figure 3 This is a schematic diagram of the partial structure of a radial section of a shell according to an embodiment of the present application;

[0018] Figure 4 A schematic diagram of the partial structure of the bottom of a cylindrical battery in one embodiment.

[0019] Figure Number:

[0020] 10-cylindrical shell; 11-side plate; 12-bottom plate; 120 liquid injection hole; 121-protrusion;

[0021] 13-transition portion; 130-arc segment; 14-insulating plate; 20-battery cell. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0023] The shell of existing batteries is usually formed using a stretching process. The shell of a cylindrical battery is usually formed into a hollow cylindrical shell with a tubular structure using a stretching process. The battery cell is placed in the shell and encapsulated by the shell. Among them, in a cylindrical battery, the shell is a cylindrical shell, and its material is metal, such as aluminum, aluminum alloy (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 shell, such as spraying an insulating coating or coating an insulating film. 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 shell by spraying, coating, or electrophoresis. The insulating film can be, for example, a polypropylene (PP) insulating film, a PE insulating film, etc.

[0024] Figure 1 The figure is a partial structural diagram of a radial section of an existing cylindrical shell. Figure 1 As shown, due to limitations in the manufacturing process, the existing cylindrical housing 10 has a flat area in the transition portion 13 between the side plate 11 and the bottom plate 12, thereby forming an edge between the side plate 11 and the bottom plate 12. The presence of this edge affects the arrangement of the insulation layer and, in turn, the insulation performance of the battery.

[0025] Taking the insulating coating as an example, when the insulating coating is formed by spraying, the presence of the edge will lead to uneven thickness of the insulating coating formed by spraying, missing of the surface insulating coating in some transition parts, etc., thereby affecting the insulation performance of the battery.

[0026] Based on this, the present application provides a cylindrical battery. Figure 2 This is a schematic structural diagram of a radial section of a cylindrical battery according to an embodiment of the present application. Figure 2As shown, the cylindrical battery includes a cylindrical shell 10 and a battery cell 20 placed in the cylindrical shell 10, and the cylindrical shell 10 is used to encapsulate the battery cell 20. The cylindrical shell 10 includes an end plate and a side plate 11 and a transition portion 13 provided 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 provided at both ends of the side plate along the axial direction of the cylindrical shell. Along the axial direction of the cylindrical shell, the end plate at the top is the top plate, and the end plate at the bottom is the bottom plate. The end plate is described below using the bottom plate as an example. It can be understood that it is also feasible to replace the bottom plate with the top plate in the structures listed below. That is, in the following embodiments of the present application, the transition portion 13 between the bottom plate 12 and the side plate 11.

[0027] Reference Figure 2 In the radial section of the cylindrical shell, 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. Figure 2 As shown, h1 is the distance from the intersection 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 of the middle transition portion 13 and the bottom plate 12 to the extension line of the side plate 11.

[0028] During measurement, the bottom plate of the cylindrical shell can be placed flat on the test bench. The vertical distance from the junction of the side plate and the transition portion to the bottom plate is h1, and the vertical distance from the junction of the bottom plate and the transition portion along the radial direction of the bottom plate to the side plate is h2. The ratio L of h1 to h2 is 0.6-1.4.

[0029] The cylindrical shell in the embodiment of the present application can be formed by cold extrusion. The bottom plate and the side plate are integrally formed by cold extrusion, which can improve the shape of the transition portion between the side plate and the bottom plate. By providing a transition portion with an arc segment, the fit between the insulation layer and the cylindrical shell can be improved, reducing the occurrence of insulation failure problems. In one embodiment, referring to Figure 2 In the radial section of the cylindrical shell 10, the arc segment 130 of the transition portion 13 can be an arc. The arc-shaped design is more conducive to the flow of the spray liquid and reduces flow resistance.

[0030] Take 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, so that the spraying liquid flows evenly from the side plate to the bottom plate. Among them, if the ratio L of the transition section dimensions h1 to h2 is too small, it is easy to spray to form an insulating coating with uneven thickness, while if the ratio L of h1 to h2 is too large, interference is likely to occur between the battery cell and the cylindrical shell, which will increase the difficulty of battery cell assembly and reduce the space for battery cell placement, which is not conducive to increasing the capacity of cylindrical batteries. The ratio of h1 to h2 is controlled within the range of 0.6-1.4, which can increase the fluidity of the spraying liquid during the spraying process, as well as the resistance of the spraying liquid when flowing in the arc-shaped transition portion, and reduce the problem of uneven spray thickness during the spraying process.

[0031] Taking the insulating film as an example, during the coating process, the insulating film and the transition portion are more closely aligned, reducing the void area between the insulating film and the transition portion. In addition to arcuate segments, in some embodiments, the transition portion may also include a small straight segment. The transition portion and the side panels, or the transition portion and the bottom panel, can be connected by welding the small straight segment. In one embodiment, the transition portion includes only arcuate segments.

[0032] In the embodiment of the present application, the dimensions of h1 and h2 can be adjusted by adjusting the dimensions of the extrusion die of the cylindrical shell. 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, or any value between any two of the above values.

[0033] In the cylindrical shell of the embodiment of the present application, the relationship between R, H and L satisfies 0≤H*|L-1| / R≤28, such as 0<H*|L-1| / R≤28, and another example is 0.5≤H*|L-1| / R≤28. Wherein, the unit of R is mm, and the unit of H is HB. By comprehensively controlling the relationship between the hardness of the cylindrical shell, the ratio L of h1 to h2, and the radius R of the arc segment, the molding of the cylindrical shell is improved, and it is convenient to form a transition portion with a uniform transition between the side plate and the bottom plate, which is conducive to the uniform coating of the insulating coating and the coating of the insulating film. At the same time, it can also avoid interference between the battery cell and the cylindrical shell when the battery cell is placed in the shell. In a preferred embodiment, the relationship between R, H and L H*|L-1| / R 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 between R, L, and H, the setting effect of the insulation layer, such as the spraying effect of the insulation coating, can be further improved.

[0034] For example, the value of H*|L-1| / R may be 0, 1, 2, 4, 5, 8, 10, 12, 15, 18, 20, 22, 25, or 28, or a value between any two of the above values.

[0035] Continue to refer to Figure 2 In one embodiment, after the battery cell 20 is installed in 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, the battery cell 20 is very likely to damage the bottom electrode when it shakes or tilts.

[0036] 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 h1 being too small, which may result in poor insulation protection of the insulation layer, and to avoid h1 being too large, which may cause interference with the cylindrical shell when the battery cell is inserted into the shell.

[0037] Exemplarily, the value of h1 can be 0.5mm, 0.6mm, 0.8mm, 1mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2.0mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm, 3.0mm, 3.2mm, 3.4mm, 3.6mm, 3.8mm, 4.0mm, etc., or a value between any two of the above values.

[0038] In one embodiment, h2 is in the range of 0.5-4 mm, preferably 1-3 mm. If h2 is too small, it will not provide sufficient support for the battery cell, which may result in uneven stress on the battery cell. If h2 is too large, the spray liquid will not flow easily to the junction of the curved transition portion and the base plate during spraying, resulting in a decrease in the quality of the sprayed insulating coating.

[0039] Exemplarily, the value of h2 can be 0.5mm, 0.6mm, 0.8mm, 1mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2.0mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm, 3.0mm, 3.2mm, 3.4mm, 3.6mm, 3.8mm, 4.0mm, etc., or a value between any two of the above values.

[0040] In one embodiment, h1 may be smaller than h2 to reduce the risk of battery shell penetration during battery assembly.

[0041] In one embodiment, the radius R of the arc segment is in the range of 1-4 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, thereby causing the spraying to form an insulating coating with uneven thickness. This increases the risk of insulation failure of the battery. The radius R of the arc segment cannot be too large. If it is too large, interference will occur between the cylindrical shell and the battery cell, and the battery cell placed inside the cylindrical shell may be prone to uneven force. Exemplarily, the value of R may 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.

[0042] In the embodiment of the present application, the radius of the arc segment in the transition portion can be measured using the three-point method, by evenly selecting three points on the arc portion to determine the radius of the corresponding circle, which is the radius of the arc segment.

[0043] The value of H ranges from 20-80 HB, preferably from 30-70 HB. If the hardness of the cylindrical shell is too high, it will be difficult to form a uniform transition during molding, which will increase the risk of sagging during spraying. The hardness of the cylindrical shell cannot be too low either, as this will weaken the cylindrical shell's ability to resist subsequent cell expansion.

[0044] For example, the value of H may be 20HB, 25HB, 30HB, 35HB, 40HB, 45HB, 50HB, 55HB, 60HB, 65HB, 70HB, 75HB, 80HB or a value between any two of the above values.

[0045] The Brinell hardness of cylindrical shells can be measured according to the national standard GB / T 231.1-2018, HBW 2.5 / 62.5. The Brinell hardness of cylindrical shells can be adjusted by adjusting the manganese and magnesium content in the components and the parameters during the material heat treatment process.

[0046] The ratio of the minimum thickness to the maximum thickness of the transition portion is less than or equal to 0.8, preferably 0.3-0.8. For example, the ratio can be 0.3, 0.4, 0.5, 0.6, 0.7, or 0.8, or any value between the above two values.

[0047] The thickness of a battery's side panels is generally thinner than the bottom panel. The transition from the side panels to the bottom panel may vary in thickness. The portion of the transition near the side panels can be thinner than the portion near the bottom panel. If the ratio of the minimum to maximum thickness of the transition section is too small, the side panels may easily crack during molding of the cylindrical shell.

[0048] In one embodiment, if Figure 2 As shown, in the axial direction of the cylindrical shell, the ratio of the height h1 of the transition portion to the height H1 of the cylindrical shell is 0.005-0.04. For example, 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 a value between any two of the above values.

[0049] The ratio of the transition portion's height h1 to the cylindrical housing's height should not be too large. If this ratio is too large, the transition portion becomes longer, increasing the risk of interference with the cylindrical housing when the battery cell is inserted. If this ratio is too small, the cylindrical housing becomes difficult to form and the risk of forming edges increases. Furthermore, if this ratio is too small, the insulation layer becomes more difficult to install, potentially leading to insulation failure.

[0050] In one embodiment, the ratio of the dimension h2 of the transition portion along the radial direction of the base plate to the diameter H2 of the cylindrical shell is 0.01-0.12. This ratio cannot be too small, otherwise the dimension of the transition portion is too small, which is not conducive to the arrangement of the insulation layer and the risk of insulation failure increases. The above ratio cannot be too large, otherwise the base plate support effect is poor. Exemplarily, the ratio of the dimension h2 of the transition portion along the radial direction of the base plate to the diameter of the base 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 a value between any two of the above values.

[0051] Figure 3 This is a partial structural diagram of a radial section of a cylindrical shell according to an embodiment of the present application. Figure 3 As shown, in one embodiment, in a radial section of the cylindrical shell 10, at the intersection of the side plate 11 and the transition portion 13, the angle a1 between the tangent line of the transition portion 13 and the extension line of the side plate 11 is less than or equal to 0° and less than or equal to 50°. The angle a1 can be measured using a microscope.

[0052] When the angle a1 is less than 50°, the occurrence of the problem of spray liquid sagging can be reduced, and the spray liquid can more easily flow along the surface of the arc-shaped transition portion toward the bottom plate.

[0053] In one embodiment, the thickness of the side panels is 0.2-0.6 mm, and the thickness of the bottom panel is 0.5-1.2 mm.

[0054] The cylindrical shell is an aluminum alloy shell, and its components include manganese and / or magnesium. The manganese accounts for 0.5-2% by weight of the total composition of the aluminum alloy shell, and the magnesium accounts for greater than 0 and less than or equal to 0.5% by weight of the total composition of the aluminum alloy shell. These manganese and magnesium contents can help improve the shell's formability.

[0055] The element composition and content of the cylindrical shell can be measured by referring to the spectral analysis method specified in GB / T 7999-2007.

[0056] Reference Figure 2 The battery cell 20 of the embodiment of the present application is placed in the cylindrical housing 10 and is encapsulated by the cylindrical housing 10. In one embodiment, a liquid injection hole 120 can 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.

[0057] The battery cell 20 in the present application may be a winding core. The winding hole of the winding core may be arranged corresponding to the 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 together.

[0058] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, while the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. There are no particular limitations on the positive electrode current collector, as long as it is conductive and does not cause adverse chemical changes in the battery. Examples include stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with one of carbon, nickel, titanium, and silver. The negative electrode current collector can be made of copper, stainless steel, nickel, titanium, or the like. In specific embodiments, 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, such as a nickel-cobalt-manganese ternary material, lithium iron phosphate material, or lithium manganese iron phosphate material. The negative electrode active material layer includes a negative electrode active material, such as artificial graphite, natural graphite, or a silicon-based material.

[0059] The separator is located between the positive and negative electrodes, separating them and preventing short circuits. The separator can be made of any material suitable for use as a separator in electrochemical energy storage devices. Specifically, the separator includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, and natural fibers.

[0060] The battery cell includes a battery body and a positive tab and a negative tab extending from the battery body. The positive tab is connected to the positive electrode sheet of the battery body, and the negative tab is connected to the negative electrode sheet of the battery body. The cylindrical shell includes a pole assembly. One of the positive tab and the negative tab is electrically connected to the pole assembly, and the other is electrically connected to the cylindrical shell.

[0061] The tab (positive or negative) can be cut from the current collector of the electrode sheet (positive or negative) or can be a separate conductive component. The tab is used to transmit current within the battery cell. The tab material can be the same as the current collector, such as aluminum or copper. For example, the positive tab and positive current collector can be aluminum, while the negative tab and negative current collector can be copper.

[0062] The cylindrical battery includes a pole assembly, which is used to connect to the external circuit, such as being connected to the pole assembly through a busbar, etc., to achieve series and parallel electrical connection of multiple batteries. The tabs are electrically connected to the pole assembly. The battery cell is a cylindrical battery cell, and the tabs can be led out from both ends of the battery cell in the axial direction, or from one end in the axial direction. One of the positive tab and the negative tab can be directly electrically connected to the pole assembly, or it can be indirectly electrically connected. When indirectly electrically connected, the tab can first be electrically connected to the current collecting disk, and the current collecting disk can then be electrically connected to the pole assembly. The other of the positive tab and the negative tab can be directly electrically connected to the cylindrical shell, or it can be indirectly electrically connected.

[0063] In some other embodiments, the battery cells may also be in other shapes, which is not limited.

[0064] Wherein, when 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 on the plane where the intersection line of the side plate and the transition part is located (such as Figure 2 Alternatively, the bottom surface of the battery cell may also be located below the plane where the intersection line of the side plate and the transition portion is located.

[0065] When the bottom surface of the battery cell is above the plane where the side panel and transition portion intersect, there is less risk when the battery cell is inserted into the housing. When the bottom surface of the battery cell is below the plane where the side panel and transition portion intersect, the battery cell can be made higher to increase energy density.

[0066] In one embodiment, the orthographic projection edge of the battery cell on the bottom plate is located within the intersection of the bottom plate and the transition portion. This assembly structure provides greater stability for the battery cell. In another embodiment, the orthographic projection edge of the battery cell on the bottom plate is located outside the intersection of the bottom plate and the transition portion. This assembly structure can increase the size of the battery cell, thereby increasing its energy density.

[0067] 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 of R is in the range of 1-4 mm, and the value of L is in the range of 0.8-1.1. Optimizing the thickness of the insulating coating on the side plate, as well as the radius of the arc segment and the value of L, can further optimize the spraying effect of the insulating coating and achieve greater thickness uniformity of the insulating coating.

[0068] 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 of this thickness can form a better coating effect and avoid problems such as warping or bulging of the insulating film caused by being too thin or too thick.

[0069] In one embodiment, between the battery cell and the bottom plate, the size of the diaphragm is larger than 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 intersection line of the side plate and the transition portion 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 portion is located. In one embodiment, at the bottom of the battery cell, the size of the diaphragm that exceeds the negative electrode sheet is 0.5-3mm. The portion of the diaphragm that exceeds the positive electrode sheet and the negative electrode sheet will be filled between the battery cell and the bottom plate to improve the insulation between the battery cell and the shell.

[0070] Figure 4 FIG. 1 is a schematic diagram of the partial structure of the bottom of a cylindrical battery according to an embodiment. Figure 4 As shown, in one embodiment, the bottom plate 12 of the cylindrical shell 10 has a protrusion 121 on the side facing the battery cell 20, which is raised toward the battery cell 20. The injection hole 120 is provided on the protrusion 121, and part of the bottom surface of the battery cell 20 contacts the protrusion 121. The protrusion 121 can be used to support the battery cell 20. At the position of the protrusion 121, the outer side of the bottom plate 12 is a groove that is recessed toward the battery cell 20. This groove is used to accommodate a sealing member for the injection hole.

[0071] In one embodiment, the diameter of the injection hole is greater than or equal to 2 mm, and the value of L is in the range of 0.8-1.4. The larger the diameter of the injection hole, the larger the area of the base plate occupied. The value of L is further limited to the range of 0.8-1.4. This can prevent the assembly of the battery and other structural components due to insufficient support area of the base plate, such as insufficient bonding area between the battery and the casing. It can also prevent the battery cell from tilting due to collision.

[0072] In one embodiment, the winding core is provided with a winding core hole, the diameter of which is greater than or equal to 4 mm, and the radius R is 1-3 mm. The winding core hole provides space for the battery cell to expand. The larger the diameter of the winding core hole, the smaller the outward expansion of the battery cell. By further controlling the radius R of the arc segment within the range of 1-3 mm, the insulation layer can be improved and the insulation performance can be enhanced.

[0073] In one embodiment, referring 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. Because a transition portion is provided between the bottom plate and the side plate. The edge of the battery cell may be in contact with 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 may be an organic polymer material, such as polyethylene or polypropylene.

[0074] In one embodiment, the distance between the battery cell and the side panel 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 panel is less than or equal to 0.8 mm, the radius of the arc segment in the transition portion needs to be relatively small to provide more space for battery cell expansion.

[0075] The following will test and illustrate the insulation performance of the cylindrical battery having the cylindrical shell of the embodiment of the present application in combination with specific embodiments and comparative examples.

[0076] Examples 1-8 and Comparative Examples 1-2 are cylindrical shells, respectively. Specific parameters of the cylindrical shells of each example and comparative example are listed in Table 1.

[0077] Table 1

[0078]

[0079] An insulating coating was sprayed on the outer surface of the cylindrical housing of each embodiment and comparative example. The compliance rate of the insulating coating thickness on the transition portion of 200 samples from each embodiment and comparative example was tested. The acceptable thickness requirement was that the ratio of the insulating coating thickness on the transition portion to the insulating coating thickness on the side panel be greater than 0.5. Furthermore, the electrode sheet was observed for any material dropout when the battery cell was inserted into the housing. The test and observation results are listed in Table 2.

[0080] Table 2

[0081]

[0082] The data in Tables 1 and 2 show that when the H*|L-1| / R value meets the range specified in this application, the compliance rate of the insulating coating thickness in the transition portion of the corresponding samples is above 90%. However, the compliance rates of the samples corresponding to Comparative Examples 1 and 2 are both below 70%. Furthermore, when the hardness of the cylindrical shell is high, causing its H*|L-1| / R value to exceed the range specified in this application, the electrode pieces are easily damaged when the battery cell is inserted into the shell, causing the electrode pieces to fall off.

[0083] For the same purpose, the present invention also provides a battery module, which may include multiple cylindrical batteries according to the present invention. The multiple cylindrical batteries may be connected in series or parallel according to specific design requirements.

[0084] Obviously, those skilled in the art may make various changes and modifications to the embodiments of the present application without departing from the spirit and scope of the present application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations.

Claims

1. A cylindrical shell, characterized in that: The cylindrical shell is an aluminum metal shell or an aluminum alloy shell, and includes an end plate and a side plate. The end plate is a circular end plate. 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 arcuate 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 arcuate 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, wherein: 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, an angle between a tangent line of the transition portion and an 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 elements; 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 0.05-2 mm.

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: The invention comprises a battery core and a cylindrical shell according to 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 roll core, and the roll core includes a positive electrode sheet, a separator and a negative electrode sheet that are wound together; At the bottom of the battery cell, the separator extends beyond 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, and the winding core is provided with a winding core hole. The aperture 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 includes a battery cell body and a positive electrode tab and a negative electrode tab extending from the battery cell body, wherein the positive electrode tab is connected to the positive electrode sheet of the battery cell body, and the negative electrode tab is connected to the negative electrode sheet of the battery cell body; The cylindrical shell includes a pole assembly, one of the positive electrode tab and the negative electrode tab is electrically connected to the pole assembly, and the other is electrically connected to the cylindrical shell.

22. A battery module, characterized in that: The invention comprises a plurality of cylindrical batteries according to any one of claims 13 to 21.

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