Cylindrical battery, battery pack, and electrical device

Abstract

The present application provides a cylindrical battery, a battery pack, and an electrical device. The cylindrical battery comprises a casing and an electrode assembly, the casing comprises a side wall and a bottom wall, the side wall and the bottom wall form an accommodating space, the side wall comprises a recess, and the recess is recessed towards the axis of the cylindrical battery; the electrode assembly is arranged in the accommodating space, the electrode assembly and the bottom wall are arranged in the axial direction of the cylindrical battery, the electrode assembly has a first end face away from the bottom wall, and the first end face is insulated from and connected to the recess; the first end face comprises a first area and a second area, and the second area is closer to the axis than the first area; in the axial direction, the projection of the recess and the projection of the first area are overlapped, and the projection of the recess is separated from the projection of the second area; in the axial direction, the distance between the first area and the bottom wall is H1, and the distance between the second area and the bottom wall is H2, wherein H2>H1.

Description

Cylindrical batteries, battery packs and electrical equipment Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a cylindrical battery, battery pack and electrical equipment. Background Technology

[0002] With the rapid development of new energy technologies, large-size, high-capacity rechargeable batteries are gradually becoming a hot market demand. The demand for large-size, high-capacity rechargeable batteries is continuously expanding in fields such as electric vehicles, energy storage systems, and power tools.

[0003] The secondary battery contains an electrode assembly inside its casing. When the secondary battery is subjected to vibration or drop, the electrode assembly can easily move within the casing, impacting other components and affecting the battery's lifespan.

[0004] Summary of the Invention

[0005] The purpose of this application is to provide a cylindrical battery, a battery pack, and an electrical device to improve the service life of the cylindrical battery, the battery pack, and the electrical device. The specific technical solution is as follows:

[0006] A first aspect of this application provides a cylindrical battery, comprising: a housing including a sidewall and a bottom wall forming a receiving space; the sidewall including a groove recessed toward the axis of the cylindrical battery; an electrode assembly disposed in the receiving space, the electrode assembly and the bottom wall arranged along the axial direction of the cylindrical battery; the electrode assembly having a first end face away from the bottom wall, the first end face being insulated from the groove; the first end face including a first region and a second region, the second region being closer to the axis than the first region; along the axial direction, the projection of the groove and the projection of the first region overlap, and the projection of the groove and the projection of the second region are separate; along the axial direction, the distance from the first region to the bottom wall is H1, and the distance from the second region to the bottom wall is H2, where H2 > H1. By pressing the first region against the groove, the portion of the electrode assembly away from the axis is compressed, and the height of the portion of the electrode assembly away from the axis is lower than the height of the portion closer to the axis. The electrode assembly forms an interference fit between the groove and the bottom wall, which helps to suppress the movement of the electrode assembly, improve the stability of the electrode assembly within the housing, and improve the service life of the cylindrical battery.

[0007] In one or more embodiments, the device further includes a first insulating member, axially positioned, at least a portion of which is disposed between the groove and the first region, connecting the groove and the first region. The groove applies pressure to the first region of the electrode assembly through the first insulating member, which helps to distribute the pressure on the electrode assembly and reduces the problem of excessively concentrated pressure on the electrode assembly.

[0008] In one or more embodiments, the projection of the first insulating member aligns with the projection of the second region along the axial direction, which helps to reduce interference of the first insulating member with other components inside the cylindrical battery and facilitates the connection of electrode assemblies and other components.

[0009] In one or more embodiments, the thickness of the first insulating member is H3, where 0.5H3≤H2-H1≤2H3, which is beneficial for the groove to press against the electrode assembly and reduce the risk of the electrode assembly shifting.

[0010] In one or more embodiments, H3≤H2-H1≤1.5H3, compared to a larger downward pressure distance on the first region, H2-H1≤1.5H3 helps to reduce the downward pressure on the electrode assembly diaphragm, thus improving the safety of the electrode assembly diaphragm. Compared to a smaller downward pressure distance on the first region, H3≤H2-H1 helps to suppress the movement of the electrode assembly.

[0011] In one or more embodiments, 0.4mm≤H3≤0.8mm is beneficial to improving the pressure-bearing capacity and insulation performance of the first insulating element.

[0012] In one or more embodiments, the first insulating element is an annular sheet, which includes an outer edge away from the axis and an inner edge close to the axis, with the outer edge closer to the bottom wall than the inner edge. This facilitates the groove pressing against the electrode assembly, reducing the risk of electrode assembly movement.

[0013] In one or more embodiments, the first insulating member includes a first surface and a second surface, the first surface being closer to the first region than the second surface; the first surface and the first plane intersect at a first intersection line, wherein the first plane is a plane including the axis; the angle between the first intersection line and the second plane perpendicular to the axis is α1, 5°≤α1≤20°. Extruding the annular sheet to create a certain angle between it and the second plane perpendicular to the axis is beneficial for improving the pressing effect of the groove on the electrode assembly and reducing the risk of electrode assembly movement.

[0014] In one or more embodiments, the first region is the region where the first insulator and the first end face are connected; along the radial direction of the cylindrical battery, the second region is connected to the first region and extends to the central hole of the electrode assembly.

[0015] In one or more embodiments, the first insulating element is made of at least one of polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, or polybutylene terephthalate. Using the above-mentioned materials for the first insulating element is beneficial for providing good insulation and cushioning performance.

[0016] In one or more embodiments, the groove includes a first groove sidewall, a groove bottom wall, and a second groove sidewall connected in sequence. The first groove sidewall is closer to the bottom wall than the second groove sidewall. The first groove sidewall includes a third surface and a fourth surface. The third surface is farther away from the second groove sidewall than the fourth surface. The third surface intersects a first plane at a second intersection line, wherein the first plane is a plane including the axis. The second groove sidewall includes a fifth surface and a sixth surface. The fifth surface is farther away from the first groove sidewall than the sixth surface. The fifth surface intersects the first plane at a third intersection line. The included angle between the second intersection line and the sidewall connected to the first groove sidewall is α2, where 60°≤α2≤70°. By designing the downward pressing angle of the first groove sidewall relative to the sidewall, it is beneficial to improve the compaction effect of the groove on the electrode assembly and suppress the movement of the electrode assembly.

[0017] In one or more embodiments, the included angle between the third intersection line and the sidewall connecting the second groove sidewall is α3, 85°≤α3≤100°. By designing the downward pressing angle of the second groove sidewall relative to the sidewall, it is beneficial to improve the compaction effect of the groove on the electrode assembly and suppress the movement of the electrode assembly.

[0018] In one or more embodiments, the depth of the groove along the radial direction of the cylindrical battery is D1, where 2mm≤D1≤4mm. This is beneficial for improving the compaction effect of the groove on the electrode assembly and suppressing the movement of the electrode assembly.

[0019] In one or more embodiments, the first insulating element is an annular sheet with a width of D2, where 2≤D2 / D1≤3. This helps to distribute the pressure on the electrode assembly and reduce the problem of excessively concentrated pressure on the electrode assembly.

[0020] In one or more embodiments, the cylindrical battery further includes: an end cap, axially aligned with the electrode assembly; the end cap has a protrusion extending toward the electrode assembly along the axial direction, and a first insulating member is disposed between the protrusion and a first region, connecting the protrusion and the first region. The protrusion and the groove together apply pressure to the electrode assembly, which helps to more securely mount the electrode assembly within the housing, further improving the compaction effect of the electrode assembly within the housing.

[0021] In one or more embodiments, the device further includes a second insulating member; the second insulating member includes a first portion, and along the axial direction, a protrusion, the first portion, the first insulating member, and a first region are arranged sequentially, the first portion connecting the protrusion and the first insulating member. The first portion and the first insulating member are both disposed between the protrusion and the first region, which is beneficial for improving the insulation effect between the protrusion and the first region.

[0022] In one or more embodiments, the diameter of the cylindrical battery is D, 30mm≤D≤100mm; and / or the length of the cylindrical battery is L, 45mm≤L≤135mm, which is beneficial for realizing large-size, high-capacity cylindrical batteries.

[0023] A second aspect of this application provides a battery pack comprising: a cylindrical battery as described in any of the above embodiments.

[0024] A third aspect of this application provides an electrical device, comprising: a battery pack or a cylindrical battery as described in any of the above embodiments.

[0025] The beneficial effects of this application are:

[0026] This application provides a cylindrical battery, battery pack, and electrical device, including a housing and an electrode assembly. The housing includes a side wall and a bottom wall, which form a receiving space. The side wall includes a groove recessed towards the axis of the cylindrical battery. The electrode assembly is disposed in the receiving space, and the electrode assembly and the bottom wall are arranged along the axial direction of the cylindrical battery. The electrode assembly has a first end face away from the bottom wall, which is insulated from the groove. The first end face includes a first region and a second region, the second region being closer to the axis than the first region. Along the axial direction, the projection of the groove and the projection of the first region overlap, while the projections of the groove and the second region are separate. The groove can apply pressure to the first region, such that along the axial direction, the distance between the first region and the bottom wall is less than the distance between the second region and the bottom wall. Compared to the prior art, in this embodiment, by compressing the first region through the groove, the first region of the electrode assembly is closer to the bottom wall than the uncompressed second region. The electrode assembly forms an interference fit between the groove and the bottom wall, which helps to suppress the movement of the electrode assembly, improves the stability of the electrode assembly within the housing, and increases the service life of the cylindrical battery, battery pack, and electrical device. Attached Figure Description

[0027] The accompanying drawings, which are provided to further illustrate this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application.

[0028] Figure 1 is a schematic diagram of the structure of a cylindrical battery according to one embodiment of this application;

[0029] Figure 2 is a partial cross-sectional view of a cylindrical battery according to one embodiment of this application;

[0030] Figure 3 is an enlarged view of A in Figure 2;

[0031] Figure 4 is a schematic diagram of the structure of the first insulating component of a cylindrical battery according to one embodiment of this application;

[0032] Figure 5 is a partial structural schematic diagram of a cylindrical battery casing according to one embodiment of this application;

[0033] Figure 6 is a schematic diagram of the battery pack provided in an embodiment of this application;

[0034] Figure 7 is a structural schematic diagram of the first type of electrical equipment provided in the embodiment of this application;

[0035] Figure 8 is a schematic diagram of the structure of the second type of electrical equipment provided in the embodiments of this application.

[0036] The reference numerals in the attached drawings are as follows: Housing 10, sidewall 11, groove 111, fifth end 111a, first groove sidewall 112, third surface 112A, fourth surface 112B, groove bottom wall 113, second groove sidewall 114, fifth surface 114A, sixth surface 114B, bottom wall 12, receiving space 13, top wall 14, electrode assembly 20, first end face 21, first region 211, first end 211a, second end 211b, second region 212, third end 212a, fourth end 212b, center hole 22, first insulating member 30, first surface 30A, second surface 30B, annular piece 31, outer edge 311, inner edge 312, end cap 40, protrusion 41, second insulating member 50, first part 51, second part 52; Axial direction X, radial direction Y, axis L0, first intersection line L1, second intersection line L2, third intersection line L3, first plane P1. The second plane P2, the distance H1 from the first region to the bottom wall, the distance H2 from the second region to the bottom wall, the thickness H3 of the first insulating member, the diameter D of the cylindrical battery, the length L of the cylindrical battery, the depth D1 of the groove, and the width D2 of the annular piece. Detailed Implementation

[0037] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0038] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to an insulated connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items.

[0039] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0040] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. Where there is no conflict, the various embodiments in this application can be combined with each other.

[0041] It should be noted that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative examples and should not constitute any limitation on this application.

[0042] The inventors realized that as the size of secondary batteries increases, the weight of the electrode components in larger secondary batteries also increases compared to smaller secondary batteries. When the secondary battery is subjected to vibration or drops, the electrode components are prone to shifting within the secondary battery casing, impacting the internal structure of the secondary battery and affecting its lifespan.

[0043] Cylindrical battery embodiment

[0044] Figure 1 is a schematic diagram of the structure of a cylindrical battery according to an embodiment of this application. In a first aspect, this application provides a cylindrical battery 100, wherein a first plane P1 is a plane containing the axis L0 of the cylindrical battery 100, and a second plane P2 is a plane perpendicular to the axis L0.

[0045] Figure 2 is a partial cross-sectional view of a cylindrical battery according to one embodiment of this application, wherein Figure 2 is a cross-sectional view of the first plane P1 of the cylindrical battery 100. Referring to Figures 1 and 2, the cylindrical battery 100 includes a housing 10 and an electrode assembly 20.

[0046] In one or more embodiments, the housing 10 includes a sidewall 11 and a bottom wall 12, which form a receiving space 13. The sidewall 11 includes a groove 111 recessed toward the axis L0 of the cylindrical battery 100. An electrode assembly 20 is disposed in the receiving space 13, and the electrode assembly 20 and the bottom wall 12 are arranged along the axial direction X of the cylindrical battery 100. The electrode assembly 20 has a first end face 21 away from the bottom wall 12, which is insulated from the groove 111. The insulated connection means that the two connected components are electrically insulated, so that current does not flow between the two components. In one or more embodiments, an insulating material is disposed between the two components, and the insulating material is connected to the two components respectively, so that current does not flow between the two components. Thus, in one or more embodiments, an insulating material is provided between the first end face 21 and the groove 111, and the insulating material is connected to the first end face 21 and the groove 111 respectively, so that current does not flow between the first end face 21 and the groove 111; the first end face 21 includes a first region 211 and a second region 212, the second region 212 is closer to the axis L0 than the first region 211, along the axial direction X, the projection of the groove 111 and the projection of the first region 211 overlap, and the projection of the groove 111 and the projection of the second region 212 are separate; along the axial direction X, the distance of the first region 211 from the bottom wall 12 is H1, and the distance of the second region 212 from the bottom wall 12 is H2, where H2 > H1.

[0047] In the above embodiment, the groove 111 presses against the first region 211 of the electrode assembly 20, such that along the axial direction X, the distance H1 between the first region 211 and the bottom wall 12 is less than the distance H2 between the second region 212 and the bottom wall 12. Specifically, the first region 211 of the electrode assembly 20, which is away from the axis L0, is pressed down by the groove 111, resulting in a smaller distance from the bottom wall 12. The first region 211 of the electrode assembly 20, which is away from the axis L0, is firmly pressed between the groove 111 and the bottom wall 12, forming an interference fit between the groove 111 and the bottom wall 12. Therefore, this helps to suppress the movement of the electrode assembly 20, improves the stability of the electrode assembly 20 within the housing 10, and increases the service life of the cylindrical battery 100.

[0048] The cylindrical battery 100 provided in the above embodiments can be applied to large-size cylindrical batteries 100, which is beneficial to improving the service life of large-size cylindrical batteries 100, but is not limited to large-size cylindrical batteries 100.

[0049] In one or more embodiments, the diameter of the cylindrical battery 100 is D, where 30mm ≤ D ≤ 100mm. For example, D can be 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, or a range of any two values ​​in between.

[0050] In one or more embodiments, the length of the cylindrical battery 100 is L, where 45mm ≤ L ≤ 135mm. For example, L can be 45mm, 50mm, 55mm, 60mm, 70mm, 80mm, 90mm, 100mm, 110mm, 120mm, 125mm, 130mm, 135mm, or a range of any two values ​​in between.

[0051] The measurement steps for H1 are as follows:

[0052] Please refer to Figure 2. The first region 211 is the force-bearing region that is pressed down by the groove 111 (including direct or indirect pressure), as shown in the dashed box on the left side of Figure 2. The distribution of this force-bearing region matches the groove 111. For example, the first region 211 includes an annular region matching the groove 111 or multiple sub-regions distributed at intervals. Along the radial direction Y of the cylindrical battery 100, from the first end 211a of the first region 211 away from the axis L0 to the second end 211b of the first region 211 near the axis L0, it is divided into 10 segments at equal distances along the radial direction Y. The distances between the two ends of the 10 segments and the inner surface of the bottom wall 12 are collected using a height gauge, resulting in 11 values. The average value is taken to obtain H1.

[0053] H2 measurement steps:

[0054] Please refer to Figure 2. The second region 212 is the area not pressed down by the groove 111, as shown in the dashed box on the right side of Figure 2. Along the radial direction Y of the cylindrical battery 100, from the third end 212a away from the axis L0 to the fourth end 212b near the axis L0, the second region 212 is divided into 10 equal segments. The distances between the two ends of the 10 segments and the inner surface of the bottom wall 12 are collected using a height gauge, resulting in 11 values. The average value is taken to obtain H2.

[0055] The steps for measuring D are as follows:

[0056] Using a Keyence IM 8000 testing instrument, 20 sampling points were evenly selected around the outer contour of the cylindrical battery 100. The center of the circle was fitted by the sampling points, and the center of the circle was connected to the 20 sampling points to form 20 lines. The 20 lines were extended and intersected with the outer contour of the cylindrical battery 100 at 20 intersection points. The distance between the sampling point and the intersection point of each line was measured, resulting in 20 values. The average value was taken to obtain the diameter D of the cylindrical battery 100.

[0057] End cap

[0058] Referring to Figures 1 and 2, in one or more embodiments, the cylindrical battery 100 further includes an end cap 40, which is arranged axially with the electrode assembly 20 along the X axis. The end cap 40 has a protrusion 41 extending toward the electrode assembly 20. The protrusion 41 and the electrode assembly 20 are insulated from each other. The protrusion 41 and the groove 111 together apply pressure to the electrode assembly 20, which helps the electrode assembly 20 to be more securely disposed within the housing 10, further improving the compaction effect of the electrode assembly 20 within the housing 10.

[0059] In one or more embodiments, the protrusion 41 of the end cap 40 is made of a metallic material, which helps to increase the strength of the protrusion 41 in applying compressive force to the electrode assembly 20.

[0060] In one or more embodiments, when viewed along the axial direction X, the protrusion 41 is a closed ring, which applies pressure to the electrode assembly 20 around the axis L0, which helps to improve the stability of the protrusion 41 pressing against the electrode assembly 20, but is not limited thereto.

[0061] First insulating component

[0062] Referring to Figure 2, in one or more embodiments, the cylindrical battery 100 further includes a first insulating member 30. Along the axial direction X, at least a portion of the first insulating member 30 is disposed between the groove 111 and the first region 211, and connects the groove 111 and the first region 211. The first insulating member 30 has a large area, which helps to disperse the pressure of the groove 111 on the electrode assembly 20 and reduce the problem of excessive pressure concentration on the electrode assembly 20.

[0063] In one or more embodiments, along the axial direction X, a first insulating member 30 is disposed between the protrusion 41 and the electrode assembly 20, and connects the protrusion 41 and the electrode assembly 20, forming insulation between the protrusion 41 and the electrode assembly 20. Both the protrusion 41 and the groove 111 press down on the first region 211 of the electrode assembly 20 through the first insulating member 30, which helps to make the force on the first region 211 more uniform.

[0064] In one or more embodiments, an insulating layer (not shown) is provided on the surface of the protrusion 41, and the insulating layer presses against the electrode assembly 20 to form an insulating connection between the protrusion 41 and the electrode assembly 20. In one or more embodiments, the insulating layer may be a polymer layer coated on the surface of the protrusion 41.

[0065] Please refer to Figure 2. In one or more embodiments, a portion of the first insulating member 30 is disposed between the groove 111 and the first region 211. The first insulating member 30 has a large area, which is beneficial for dispersing the pressure on the electrode assembly 20 and reducing the problem of excessively concentrated pressure on the electrode assembly 20.

[0066] In one or more embodiments, the entire first insulating member 30 is disposed between the groove 111 and the first region 211 (not shown). The area of ​​the first insulating member 30 is small, which helps to reduce the interference of the first insulating member 30 with other components inside the cylindrical battery 100 and facilitates the connection of the electrode assembly 20 and other components.

[0067] In one or more embodiments, the first region 211 includes a region indirectly pressurized by a groove 111, which presses against a first insulating member 30, and the first insulating member 30 presses against the first region 211. The first region 211 includes the region where the first insulating member 30 and the first end face 21 are connected.

[0068] In one or more embodiments, the second region 212 includes the area where the first insulator 30 and the first end face 21 are not connected. Along the axial direction X, the projection of the first insulator 30 is adjacent to the projection of the second region 212 of the first end face 21, which helps to reduce the interference of the first insulator 30 with other components inside the cylindrical battery 100, such as the current collector, and facilitates the connection between the current collector and the electrode assembly.

[0069] In the radial direction Y, the second region 212 is connected to the first region 211 and extends to the center hole 22 of the electrode assembly 20.

[0070] Figure 3 is an enlarged view of A in Figure 2. As shown in Figure 3, the first insulating member 30 includes a first surface 30A and a second surface 30B. The first surface 30A is closer to the first region 211 than the second surface 30B. The thickness between the first surface 30A and the second surface 30B of the first insulating member 30 is H3.

[0071] H3 measurement steps:

[0072] The steps for measuring the thickness H3 of the first insulating component 30 include: removing the first insulating component 30 from the casing 10 of the cylindrical battery 100; flattening the first insulating component 30; in the flattened state (not shown), the outer edge 311 and inner edge 312 of the first insulating component 30 are approximately in the same plane; randomly selecting 10 different areas on the surface of the first insulating component 30; measuring the thickness of the 10 areas using a height gauge; and taking the average value to obtain the thickness H3 of the first insulating component 30.

[0073] In one or more embodiments, the degree of downward pressure of the first region 211 can be adjusted according to the operating conditions of the cylindrical battery 100.

[0074] In one or more embodiments, 0.5H3≤H2-H1≤2H3, for example, H2-H1 can be: 0.5H3, 0.6H3, 0.7H3, 0.8H3, 0.9H3, 1H3, 1.1H3, 1.2H3, 1.3H3, 1.4H3, 1.5H3, 1.6H3, 1.7H3, 1.8H3, 1.9H3, 2H3 or any two values ​​in between, which is beneficial for suppressing the movement of the electrode assembly 20.

[0075] In one or more embodiments, the first region 211 is pressed down to a suitable distance, H3 ≤ H2 - H1 ≤ 1.5H3. A moderate pressing distance on the first region 211 of the electrode assembly 20, compared to a larger pressing distance, H2 - H1 ≤ 1.5H3, helps to reduce the downward pressure on the diaphragm in the electrode assembly 20, improving the safety of the diaphragm in the electrode assembly 20. Compared to a smaller pressing distance on the first region 211, H3 ≤ H2 - H1 helps to suppress the movement of the electrode assembly 20.

[0076] The first insulating member 30 provides buffering and insulation between the electrode assembly 20 and the recess 111. In one or more embodiments, 0.4 mm ≤ H3 ≤ 0.8 mm. For example, H3 can be 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, or any range of two values ​​in between. For harsher operating conditions, using a thicker first insulating member 30 is beneficial for improving the safety of the cylindrical battery 100. For more stable operating conditions, using a thinner first insulating member 30 is beneficial for reducing the space occupied by the first insulating member 30 and increasing the volumetric energy density of the cylindrical battery 100.

[0077] In one or more embodiments, 38.2mm ≤ H1 ≤ 127.4mm. For example, H1 can be: 38.2mm, 40mm, 45mm, 48.2mm, 48.4mm, 48.6mm, 48.8mm, 50mm, 55mm, 60mm, 65mm, 70mm, 72.8mm, 73.1mm, 73.4mm, 73.7mm, 75mm, 80mm, 85mm, 90mm, 95mm, 100mm, 105mm, 110mm, 112.4mm, 112.8mm, 113.2mm, 113.6mm, 115mm, 120mm, 125mm, 127mm, 127.4mm, or a range of any two values ​​in between.

[0078] In one or more embodiments, 39mm ≤ H2 ≤ 129mm. For example, H2 can be: 39mm, 40mm, 45mm, 49mm, 50mm, 55mm, 60mm, 65mm, 70mm, 74mm, 75mm, 80mm, 85mm, 90mm, 95mm, 100mm, 105mm, 110mm, 114mm, 115mm, 120mm, 125mm, 129mm, or a range of any two values ​​in between.

[0079] Figure 4 is a schematic diagram of the structure of the first insulating member 30 of a cylindrical battery 100 according to one embodiment of this application. Referring to Figures 2 and 4, in one or more embodiments, the first insulating member 30 is an annular piece 31, and the groove 111 is an annular groove, but is not limited thereto. In one or more embodiments, the first region 211 is an annular first region. The annular groove presses down on the annular piece 31, and the annular piece 31 presses down on the annular first region. Observed along the axis X, the annular groove is a closed ring, and the pressure on the electrode assembly 20 is relatively uniform. Applying pressure to the electrode assembly 20 around the axis L0 is beneficial to improving the stability of the groove 111 pressing against the electrode assembly 20.

[0080] Referring to Figures 1 and 3, the first surface 30A and the first plane P1 intersect at the first intersection line L1; the angle between the first intersection line L1 and the second plane P2 perpendicular to the axis is α1.

[0081] Measurement steps for α1:

[0082] The cylindrical battery 100 was scanned using an industrial CT scanner (Zeiss Xradia 620 Versa) and displayed as a three-dimensional image. A cross-section was taken in the first plane P1, and the angle between the first intersection line L1 and the second plane P2 was measured. Along the circumference of the cylindrical battery 100, a cross-section was randomly taken in a plane containing the axis L0, and the angle between the first intersection line L1 and the second plane P2 was measured. Ten measurements were obtained, and the average value was taken to obtain α1.

[0083] In one or more embodiments, 5° ≤ α1 ≤ 20°. For example, α1 can be 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°, 19°, 20°, or a range of any two values ​​in between. Pressing the annular piece 31 to form a certain angle with the second plane P2 perpendicular to the axis L0 helps improve the pressing effect of the groove 111 on the electrode assembly 20 and reduces the risk of the electrode assembly 20 shifting.

[0084] In one or more embodiments, the first surface 30A is attached to the first region 211.

[0085] For more severe operating conditions, α1 is compressed to a larger angle to improve the compaction effect of the electrode assembly 20 within the housing 10.

[0086] In one or more embodiments, the first insulating element 30 is made of at least one of polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, or polybutylene terephthalate. Using the above-mentioned materials for the first insulating element 30 is beneficial for providing good insulation and cushioning performance.

[0087] Figure 4 is a schematic diagram of the structure of the first insulating member of a cylindrical battery according to one embodiment of this application. Referring to Figures 2 and 4, in one or more embodiments, the outer edge 311 of the annular piece 31 is closer to the bottom wall 12 than the inner edge 312, and the inner edge 312 of the annular piece 31 is inclined away from the bottom wall 12. The annular piece 31 fits more tightly with the first region 211 of the electrode assembly 20, which is beneficial for the groove 111 to press against the electrode assembly 20 and reduce the risk of the electrode assembly 20 shifting.

[0088] In embodiments where the outer edge 311 of the annular piece 31 is closer to the bottom wall 12 than the inner edge 312, the groove 111 presses against the outer edge 311 of the annular piece 31. The overall area of ​​the annular piece 31 is relatively large, which is beneficial to disperse the pressure on the electrode assembly 20 and reduce the problem of excessively concentrated pressure on the electrode assembly 20.

[0089] In one or more embodiments, the groove 111 presses against the inner edge 312 (not shown) of the annular piece 31. The outer edge 311 of the annular piece 31 is farther away from the bottom wall 12 than the inner edge 312. The overall area of ​​the annular piece 31 is small, which helps to reduce the interference of the first insulating member 30 to other components inside the cylindrical battery 100 and facilitates the connection of the electrode assembly 20 and other components (such as the current collector).

[0090] Second insulating component

[0091] Please refer back to Figures 2 and 3. In one or more embodiments, a second insulating member 50 is further included. The second insulating member 50 includes a first portion 51. Along the axial direction X, a protrusion 41, the first portion 51, the first insulating member 30, and a first region 211 are arranged sequentially. The first portion 51 connects the protrusion 41 and the first insulating member 30. Both the first portion 51 and the first insulating member 30 are disposed between the protrusion 41 and the first region 211, which helps to improve the insulation effect between the protrusion 41 and the first region 211.

[0092] Referring to Figure 3, in one or more embodiments, the second insulating member 50 further includes a second portion 52, which is connected to the first portion 51. At least a portion of the second portion 52 is disposed between the housing 10 and the end cap 40, and connects the housing 10 and the end cap 40 respectively, so as to facilitate the insulating connection between the housing 10 and the end cap 40.

[0093] case

[0094] Figure 5 is a partial structural schematic diagram of a cylindrical battery casing according to one embodiment of this application. As shown in Figure 5, in one or more embodiments, the casing 10 can be made of metal, and correspondingly, the groove 111 can be made of metal. In one or more embodiments, the casing 10 can be made of steel or aluminum, etc.

[0095] The groove 111 is made of metal, which gives it a certain strength and allows it to press down on the first region 211 of the electrode assembly 20. This causes the first region 211 to be stably compressed towards the bottom wall 12 compared to the second region 212, and presses the electrode assembly 20 firmly between the groove 111 and the bottom wall 12. This helps to reduce the probability of the electrode assembly 20 moving around inside the housing 10 in a bumpy environment.

[0096] In one or more embodiments, an insulating layer (not shown) is provided between the groove 111 and the electrode assembly 20. The insulating layer is disposed on the inner surface of the groove 111, so that the groove 111 has high strength and good insulation performance.

[0097] In one or more embodiments, the insulating layer is applied using a surface spraying process. In one or more embodiments, an Al2O3-Cr2O3 composite oxide ceramic coating is formed on the inner surface of the groove 111. This coating has good electrical insulation properties, which is beneficial for the insulating connection between the first end face 21 and the groove 111.

[0098] The inventors realized that, compared to large-size cylindrical batteries, the electrode components of small-size cylindrical batteries account for a smaller proportion of the overall weight of the cylindrical battery. Furthermore, the electrode components are lighter and have less inertia. Therefore, when the electrode components move around in a bumpy environment, the impact force of the electrode components on the internal structure of the battery casing is also smaller.

[0099] The inventors realized that for large-sized batteries, the electrode assembly accounts for a large proportion of the overall weight of the cylindrical battery. Moreover, the electrode assembly is heavy and has great inertia. When the electrode assembly moves around in a bumpy environment, the internal structure of the battery casing is subjected to repeated impacts from the electrode assembly, making it more prone to fatigue fracture of the internal structure compared to small-sized batteries.

[0100] In the scheme for implementing the groove 111 to compact the electrode assembly 20, there are no specific restrictions on the specific shape of the groove 111.

[0101] Referring to Figures 2 and 5, in one or more embodiments, the groove 111 includes a first groove sidewall 112, a groove bottom wall 113, and a second groove sidewall 114 connected in sequence, with the first groove sidewall 112 closer to the bottom wall 12 than the second groove sidewall 114. In one or more embodiments, the groove bottom wall 113 connects the first groove sidewall 112 and the second groove sidewall 114. In one or more embodiments, both the first groove sidewall 112 and the second groove sidewall 114 apply pressure to the electrode assembly 20, which helps to provide a more stable downward pressure structure for the electrode assembly 20.

[0102] Please refer to Figure 5. In one or more embodiments, the first groove sidewall 112 includes a third surface 112A and a fourth surface 112B. The third surface 112A is farther away from the second groove sidewall 114 than the fourth surface 112B. The third surface 112A intersects the first plane P1 at a second intersection line L2. The second groove sidewall 114 includes a fifth surface 114A and a sixth surface 114B. The fifth surface 114A is farther away from the first groove sidewall 112 than the sixth surface 114B. The fifth surface 114A intersects the first plane P1 at a third intersection line L3. The included angle between the second intersection line L2 and the sidewall connected to the first groove sidewall 112 is α2, 60°≤α2≤70°. For example, α2 can be 60°, 61°, 62°, 63°, 64°, 65°, 66°, 67°, 68°, 69°, 70° or a range consisting of any two values ​​in between. By designing the downward pressing angle of the first groove sidewall 112 relative to the sidewall, it is beneficial to improve the compaction effect of the groove on the electrode assembly and suppress the movement of the electrode assembly.

[0103] In one or more embodiments, the included angle between the third intersection line L3 and the sidewall connecting the second groove sidewall 114 is α3, where 85°≤α3≤100°. For example, α3 can be 85°, 86°, 87°, 88°, 89°, 90°, 91°, 92°, 93°, 94°, 95°, 96°, 97°, 98°, 99°, 100°, or a range of any two values ​​in between. By designing the downward pressing angle of the second groove sidewall 114 relative to the sidewall, it is beneficial to improve the compaction effect of the groove on the electrode assembly and suppress the movement of the electrode assembly.

[0104] Measurement steps for α2 and α3:

[0105] The cylindrical battery 100 was scanned using an industrial CT scanner (Zeiss Xradia 620 Versa) and displayed as a three-dimensional image. A cross-section was performed on the first plane P1 to measure the angle between the second intersection line L2 and the sidewall connected to the first groove sidewall 112. Along the circumference of the cylindrical battery 100, cross-sections were randomly performed on the plane containing the axis L0 to measure the angle between the second intersection line L2 and the sidewall connected to the first groove sidewall 112. Ten measurements were obtained, and the average value was taken to obtain α2.

[0106] The test method for the included angle α3 between the third intersection line L3 and the side wall connected to the second groove side wall 114 is the same as that for α2, and will not be repeated here.

[0107] In one or more embodiments, the groove 111 is a closed annulus; for example, the groove 111 includes an annular groove disposed around the sidewall 11. Correspondingly, the first region 211 is an annular region.

[0108] In one or more embodiments, there are at least two grooves 111 (not shown), for example, at least two grooves 111 are distributed around the sidewall 11. Correspondingly, the first region 211 includes a plurality of sub-regions spaced around the axis L0.

[0109] Please refer to Figure 5. In one or more embodiments, the housing 10 further includes a top wall 14, which is formed by folding the side wall 11 inward. In one or more embodiments, the top wall 14 presses down on the groove 111 in the axial direction X, forming a downward pressure on the groove 111, causing the groove 111 to squeeze the first region 211 of the electrode assembly 20, further improving the structural stability of the groove 111, which helps to reduce the risk of the electrode assembly 20 moving around.

[0110] Measurement steps for D1:

[0111] Please refer to Figure 5. In the first plane P1 containing the axis L0, the groove 111 includes a fifth end 111a near the axis L0, through which internal components such as the electrode assembly 20 inside the housing 10 are taken out.

[0112] Ten different first planes are uniformly selected around the axis L0 of the housing 10. Along the radial Y of the cylindrical battery 100, the distance from the fifth end 111a to the outer surface of the side wall 11 is measured using vernier calipers. After obtaining the ten measurements, the average value is taken to obtain the depth D1 of the groove 111.

[0113] In one or more embodiments, 2mm≤D1≤4mm, for example, D1 can be: 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4mm or any two values ​​in between, which is beneficial to improve the compaction effect of the groove 111 on the electrode assembly 20 and suppress the movement of the electrode assembly 20.

[0114] In this application, the width of the annular piece 31 is D2 along the radial direction Y of the cylindrical battery 100.

[0115] The measurement steps for D2 are as follows:

[0116] An annular piece 31 is removed from the casing 10 of the cylindrical battery 100 and flattened. In the flattened state (not shown), the outer edge 311 and inner edge 312 of the annular piece 31 are approximately in the same plane. Using a Keyence IM 8000 tester, 20 points are evenly selected around the outer edge 311 of the flattened annular piece 31. A center is fitted to these 20 points. The center is then connected to each of the 20 points on the outer edge 311, forming 20 lines. These 20 lines are extended to intersect the inner edge 312 of the flattened annular piece at 20 points. The widths of the intersection points of the outer edge 311 and the inner edge 312 along these 20 lines are measured, and the average value is taken to obtain the width D2 of the annular piece 31.

[0117] In one or more embodiments, 2≤D2 / D1≤3. For example, D2 / D1 can be 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3 or any two values ​​in between. This helps to distribute the pressure on the electrode assembly 20 and reduce the problem of excessively concentrated pressure on the electrode assembly 20.

[0118] In one or more embodiments, 4≤D2≤10. For example, D2 can be 4, 5, 6, 7, 8, 9, 10 or any two values ​​in between. This helps to distribute the pressure on the electrode assembly 20 and reduce the problem of excessively concentrated pressure on the electrode assembly 20.

[0119] Electrode assembly

[0120] In one or more embodiments, the electrode assembly 20 employs a multi-tab wound structure (not shown). The multi-tab wound structure includes a first electrode, a second electrode, and a diaphragm.

[0121] The first electrode, separator, and second electrode are stacked sequentially and wound together. The first electrode includes a first current collector and a first active coating. The first current collector includes a first coating area and a first empty foil area. The first active coating is disposed in the first coating area. In the winding structure, the portion of the first empty foil area away from the first coating area is flattened to form a first flattened area. The first flattened area serves as the first multi-tab electrode, and the first multi-tab electrode forms a first end face 21 away from the bottom wall 12. Normally, the first multi-tab electrode is in a fluffy state. When the cylindrical battery 100 is in a vibrating environment, the first multi-tab electrode will gradually be compacted from a fluffy state, thus reducing its thickness. This makes the electrode assembly 20 prone to movement within the housing 10 after repeated bumping. In this example, the first region 211 corresponding to the first multi-tab electrode is compacted. Therefore, when the cylindrical battery 100 is in a bumpy environment, it helps to improve the stability of the electrode assembly 20 within the housing 10.

[0122] In one or more embodiments, the second electrode includes a second current collector and a second active coating. The second current collector includes a second coating area and a second empty foil area. The second active coating is disposed in the second coating area. The portion of the second empty foil area away from the second coating area is flattened to form a second flattened area. The second flattened area serves as a second multi-tab electrode. The arrangement of the multi-tab electrode is beneficial to reducing the internal resistance of the cylindrical battery 100.

[0123] Battery Pack Example

[0124] Figure 6 is a schematic diagram of the structure of the battery pack provided in the embodiment of this application. As shown in Figure 6, in a second aspect, this application provides a battery pack 200, including the cylindrical battery 100 in the above embodiment.

[0125] In one or more embodiments, there is one cylindrical battery 100. In one or more embodiments, as shown in FIG6, there are multiple cylindrical batteries 100, which are connected in series or in parallel, or in a combination of series and parallel connections.

[0126] In one or more embodiments, as shown in FIG6, the battery pack 200 includes a battery pack housing 201, and at least one cylindrical battery 100 is disposed within the battery pack housing 201.

[0127] Example of electrical equipment

[0128] Figure 7 is a structural schematic diagram of the first type of electrical device provided in the embodiment of this application. As shown in Figure 7, in a third aspect, this application provides an electrical device 300, which includes the battery pack 200 in the above embodiment, and the battery pack 200 includes the cylindrical battery 100 in the above embodiment.

[0129] Figure 8 is a schematic diagram of the structure of a second type of electrical device provided in the embodiment of this application. As shown in Figure 8, unlike the electrical device 300 mentioned above which includes a battery pack 200, in this embodiment, the electrical device 300 includes the cylindrical battery 100 in the above embodiment.

[0130] This application does not specifically limit the electrical equipment used, but includes electrical equipment known in the prior art. For example, electrical equipment includes, but is not limited to, computers, smartphones, backup power supplies, two-wheeled vehicles, drones, power tools, energy storage devices, etc.

[0131] Example

[0132] The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below.

[0133] Test equipment:

[0134] Octahedral roller: The inner diameter of the roller is 230mm, the length is 230mm, and the wall thickness is 10mm.

[0135] Roller test method:

[0136] Cylindrical batteries were subjected to an octahedral roller test at a speed of 66 revolutions per minute for 100 minutes. The resistance and terminal voltage of the cylindrical batteries before and after the test were compared.

[0137] The criteria for passing the drum test are: the change in battery terminal voltage before and after the test is within 100mV, and the change in battery resistance is within 20%. The criteria for failing the test are: the change in battery terminal voltage before and after the test is greater than 100mV, or the change in battery resistance is greater than 20%.

[0138] The battery terminal voltage can be tested using a battery tester (model: Neware CT-4016-5V-100A), and the battery resistance can be tested using an internal resistance tester (model: HIOKI BT3563).

[0139] To verify the shock resistance of the cylindrical battery in this application, 12 sets of example tests and 3 sets of comparative tests were conducted, as follows:

[0140] In each set of embodiments, there are 12 cylindrical batteries. Each cylindrical battery is provided with a groove and electrode assembly with an interference fit as described in this application, where H2 > H1. The specific dimensions of the cylindrical batteries in each set of embodiments are shown in Table 1.

[0141] Each comparative example contains 12 cylindrical batteries, with H1 = H2 for each cylindrical battery. The specific dimensions of the cylindrical batteries in each comparative example are shown in Table 1.

[0142] Each of the aforementioned examples and comparative examples was subjected to a roller test. After the examples and comparative examples completed the test, the number of cylindrical batteries that passed the test (Q1) and the number of cylindrical batteries that failed the test (Q2) were counted in each test group. Q1 + Q2 = 12, as shown in Table 1.

[0143] Remark:

[0144] D is the diameter of the cylindrical battery;

[0145] L is the length of the cylindrical battery;

[0146] H1 is the distance from the first region to the bottom wall;

[0147] H2 is the distance of the second region from the bottom wall;

[0148] H3 is the thickness of the first insulating component;

[0149] α1 is the angle between the first line of intersection and the second plane;

[0150] α2 is the angle between the second intersection line and the sidewall connecting the first groove sidewall;

[0151] α3 is the angle between the third intersection line and the sidewall connecting the second groove sidewall;

[0152] D1 is the depth of the groove;

[0153] D2 is the width of the annular piece;

[0154] Q1 represents the number of cylindrical batteries tested in each set of examples and comparative examples.

[0155] As shown in Table 1, in Examples 1 to 12, all 12 cylindrical batteries in each of the 12 sets of examples in Table 1 passed the tumbling test.

[0156] In Comparative Examples 1 to 3, among the three sets of comparative examples in Table 1 above, 10 out of the 12 cylindrical batteries in each set passed the tumbling test, while 2 cylindrical batteries failed the tumbling test.

[0157] The pass rate of the cylindrical battery roller test in the embodiments of this solution is greater than that in the comparative cylindrical battery roller test. The roller test can verify that the cylindrical battery in the embodiments of this application has better drop resistance and shock resistance.

[0158] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A cylindrical battery, characterized in that, include: The housing includes a side wall and a bottom wall, the side wall and the bottom wall forming a receiving space, the side wall including a groove recessed toward the axis of the cylindrical battery; An electrode assembly is disposed in the receiving space, the electrode assembly and the bottom wall are arranged along the axial direction of the cylindrical battery, the electrode assembly has a first end face away from the bottom wall, the first end face being insulated from the groove; The first end face includes a first region and a second region. The second region is closer to the axis than the first region. Along the axial direction, the projection of the groove overlaps with the projection of the first region, and the projection of the groove is separate from the projection of the second region. Along the axial direction, the distance from the first region to the bottom wall is H1, and the distance from the second region to the bottom wall is H2, where H2 > H1.

2. The cylindrical battery according to claim 1, characterized in that, Also includes: A first insulating element, along the axial direction, at least a portion of which is disposed between the groove and the first region, and connects the groove and the first region.

3. The cylindrical battery according to claim 2, characterized in that, Along the axial direction, the projection of the first insulating element is adjacent to the projection of the second region.

4. The cylindrical battery according to claim 2 or 3, characterized in that, The thickness of the first insulating element is H3, and 0.5H3≤H2-H1≤2H3.

5. The cylindrical battery according to claim 4, characterized in that, H3≤H2-H1≤1.5H3.

6. The cylindrical battery according to any one of claims 2 to 5, characterized in that, 0.4mm≤H3≤0.8mm.

7. The cylindrical battery according to any one of claims 2 to 6, characterized in that, The first insulating element is an annular sheet, which includes an outer edge away from the axis and an inner edge close to the axis, with the outer edge being closer to the bottom wall than the inner edge.

8. The cylindrical battery according to claim 7, characterized in that, The first insulating element includes a first surface and a second surface, wherein the first surface is closer to the first region than the second surface; The first surface and the first plane intersect at a first line of intersection, wherein the first plane is a plane that includes the axis. The angle between the first intersection line and the second plane perpendicular to the axis is α1, where 5°≤α1≤20°.

9. The cylindrical battery according to any one of claims 2 to 8, characterized in that, The first region is the area where the first insulating element and the first end face are connected; Along the radial direction of the cylindrical battery, the second region connects with the first region and extends to the central hole of the electrode assembly.

10. The cylindrical battery according to any one of claims 2 to 9, characterized in that, The material of the first insulating element includes at least one of polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, or polybutylene terephthalate.

11. The cylindrical battery according to any one of claims 1 to 10, characterized in that, The groove includes a first groove sidewall, a groove bottom wall, and a second groove sidewall connected in sequence, wherein the first groove sidewall is closer to the bottom wall than the second groove sidewall; The first groove sidewall includes a third surface and a fourth surface, the third surface being farther away from the second groove sidewall than the fourth surface, the third surface intersecting the first plane at a second intersection line, wherein the first plane is a plane containing the axis; The second groove sidewall includes a fifth surface and a sixth surface, the fifth surface being farther away from the first groove sidewall than the sixth surface, and the fifth surface intersecting the first plane at a third intersection line; The angle between the second intersection line and the sidewall connecting to the first groove sidewall is α2, where 60°≤α2≤70°; and / or, The included angle between the third intersection line and the sidewall connecting the second groove sidewall is α3, where 85°≤α3≤100°.

12. The cylindrical battery according to any one of claims 1 to 11, characterized in that, Along the radial direction of the cylindrical battery, the depth of the groove is D1, where 2mm≤D1≤4mm.

13. The cylindrical battery according to claim 12, characterized in that, The first insulating element is an annular sheet, and the width of the annular sheet is D2, where 2≤D2 / D1≤3.

14. The cylindrical battery according to any one of claims 2 to 13, characterized in that, Also includes: End caps, arranged along the axial direction with the electrode assembly; The end cap has a protrusion that extends toward the electrode assembly; Along the axial direction, the first insulating member is disposed between the protrusion and the first region, and connects the protrusion and... The first region.

15. The cylindrical battery according to claim 14, characterized in that, Also includes: Second insulating component; The second insulating member includes a first portion, and along the axial direction, the protrusion, the first portion, the first insulating member, and the first region are arranged sequentially, with the first portion connecting the protrusion and the first insulating member.

16. The cylindrical battery according to any one of claims 1 to 15, characterized in that, The diameter of the cylindrical battery is D, 30mm ≤ D ≤ 100mm; and / or, The length of the cylindrical battery is L, where 45mm ≤ L ≤ 135mm.

17. A battery pack, characterized in that, include: The cylindrical battery according to any one of claims 1 to 16.

18. An electrical appliance, characterized in that, include: The battery pack according to claim 17 or the cylindrical battery according to any one of claims 1 to 16.

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