Secondary battery and battery pack

Abstract

The utility model provides a kind of secondary battery, comprising: shell, one end is equipped with opening, and the other end is equipped with end wall in opposite with opening;Pole, pass in and set on end wall, along the axial pole of shell the end close to opening is provided with welding area;Electrode assembly, set in shell;Lower plastic, clamped between the inner surface of end wall towards electrode assembly and pole;Current collector, it is set between pole and electrode assembly, current collector includes first subarea and second subarea, along the radial second subarea of shell is connected in the outside of first subarea, wherein, lower plastic has protruding part, protruding part is more close to electrode assembly in axial compared with the welding area of pole, along the direction of electrode assembly and press second subarea, so that first subarea is attached welding area, and first subarea is welded with welding area.The utility model aims at providing a kind of secondary battery and battery pack, to improve the safety performance of secondary battery at least.

Description

Technical Field

[0001] The embodiments of this utility model relate to a secondary battery and a battery pack. Background Technology

[0002] A secondary battery consists of terminals, electrode assemblies, and current collectors, which electrically connect the electrode assemblies and terminals. If a gap exists between the terminals and current collectors during welding, it may result in poor welding, reduced current carrying capacity, and consequently, compromised safety performance of the secondary battery. Utility Model Content

[0003] In view of the problems existing in the related technologies, the purpose of this utility model is to provide a secondary battery and battery pack to at least improve the safety performance of the secondary battery.

[0004] To achieve the above objectives, this utility model provides a secondary battery, comprising: a housing with an opening at one end and an end wall at the other end opposite to the opening; an electrode post passing through the end wall, with a welding area provided at the end of the electrode post near the opening along the axial direction of the housing; an electrode assembly disposed within the housing; a lower plastic core sandwiched between the inner surface of the end wall facing the electrode assembly and the electrode post; and a current collector disposed between the electrode post and the electrode assembly, the current collector comprising a first partition and a second partition, the second partition being connected to the outside of the first partition along the radial direction of the housing, wherein the lower plastic core has a protrusion that is closer to the electrode assembly in the axial direction than the welding area of ​​the electrode post, and presses against the second partition in the direction toward the electrode assembly, thereby causing the first partition to conform to the welding area, and the first partition to be welded to the welding area.

[0005] The beneficial technical effects of this utility model are as follows: In the embodiments of this application, the collector plate and the protruding part of the lower plastic cooperate with each other. The protruding part of the lower plastic presses against the second partition located on the outer ring of the collector plate, so that the first partition in the center of the collector plate tilts up towards the pole post to fit tightly against the pole post. This prevents the first partition from moving along the axial direction towards the end cover, increases the fit between the first partition of the collector plate and the pole post, and improves the welding yield.

[0006] In some embodiments, the secondary battery further includes: insulating tape comprising a first portion adhered to the outer peripheral side of the electrode assembly and a second portion connected to the first portion, the second portion being adhered to the second partition, the protrusion pressing the second portion against the surface of the second partition away from the electrode assembly.

[0007] In some embodiments, the protrusion extends along the axial direction from the pole post to the electrode assembly, and the protrusion height of the protrusion relative to the welding area of ​​the pole post is h1 mm, where 0.05 ≤ h1 ≤ 0.6.

[0008] In some embodiments, the distance from the protrusion to the axis of the housing is a mm, the radius of the collector is b mm, and 0.6 ≤ a / b ≤ 0.95.

[0009] In some embodiments, the outermost edge of the lower plastic extends beyond the outer periphery of the electrode assembly along the radial direction outward.

[0010] In some embodiments, the current collector is welded to the tabs of the electrode assembly facing the pole to form a first weld mark, the second portion covers at least a portion of the current collector and the first weld mark, the width of the second portion in the radial direction is W1 mm, the radius of the electrode assembly is W2 mm, and 0.1≤W1 / W2≤0.5.

[0011] In some embodiments, the current collector is welded to the tabs of the electrode assembly facing the pole to form a first weld mark, and the welding area of ​​the pole and the first partition are welded to form a second weld mark. The first weld mark and the second weld mark do not overlap and are spaced apart by a distance ≥0.5mm in the radial direction.

[0012] In some embodiments, the electrode post has a groove with an opening opposite to the manifold, the bottom wall of the groove has an injection hole, the bottom wall is the welding area and is welded to the first partition to form a second weld mark, the electrode assembly is a wound body with a central hole, the manifold has a through hole connecting the injection hole and the central hole, the diameter of the through hole is D1 mm, the diameter of the injection hole is D2 mm, 0.4≤D2 / D1≤0.9, and a sealing nail seals the injection hole and passes through the through hole.

[0013] In some embodiments, the projection of the through hole onto the electrode assembly along the axial direction falls into the central hole.

[0014] Embodiments of this application also provide a battery pack, the battery pack comprising any of the above-described secondary batteries. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. It is worth noting that, according to industry standard practice, the components are not drawn to scale and are only used for illustrative purposes. In fact, for clarity of discussion, the dimensions of the components can be arbitrarily increased or decreased.

[0016] Figure 1A front view of a cylindrical battery according to an embodiment of this application is shown.

[0017] Figure 2 A top view of a cylindrical battery according to an embodiment of this application is shown.

[0018] Figure 3 It shows along Figure 1 A cross-sectional view taken from the BB line.

[0019] Figure 4 It shows along Figure 2 A cross-sectional view taken from the JJ line.

[0020] Figure 5 A top view of the manifold and electrode assembly according to an embodiment of this application is shown.

[0021] Figure 6 It shows along Figure 5 A cross-sectional view taken from the CC line.

[0022] Figure 7 A battery pack according to an embodiment of this application is shown.

[0023] Figure 8 A schematic diagram is shown when the electrical device in an embodiment of this application is a vehicle. Detailed Implementation

[0024] To better understand the spirit of the embodiments of this application, the following description is based on some preferred embodiments of this application.

[0025] Embodiments of this application will be described in detail below. Throughout this specification, identical or similar components and components having identical or similar functions are indicated by similar reference numerals. The embodiments described herein with reference to the accompanying drawings are illustrative and diagrammatic in nature and are intended to provide a basic understanding of this application. The embodiments of this application should not be construed as limiting this application.

[0026] The terms “approximately,” “generally,” “substantial,” “substantial,” “about,” and “approximately” used herein are used to indicate and explain minor variations. For example, when used in conjunction with numerical values, the above terms may refer to a range of variation less than or equal to ±10% of the corresponding numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. As another embodiment, the thickness of a film or layer being “substantially uniform” may refer to the average thickness of the film or layer being less than or equal to ±10% of the standard deviation, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. The term "substantially coplanar" can refer to two surfaces that are within 50 μm along the same plane (such as within 40 μm, 30 μm, 20 μm, 10 μm, or 1 μm along the same plane). If, for example, two components overlap or overlap within 200 μm, 150 μm, 100 μm, 50 μm, 40 μm, 30 μm, 20 μm, 10 μm, or 1 μm, then the two components can be considered "substantially aligned." If the angle between two surfaces or components is, for example, 90° ± 10° (such as ± 5°, ± 4°, ± 3°, ± 2°, ± 1°, ± 0.5°, ± 0.1°, or ± 0.05°), then the two surfaces or components can be considered "substantially perpendicular." When used in conjunction with an event or situation, the terms "approximately," "generally," "substantially," "materially," "about," and "approximately" can refer to the exact occurrence of the event or situation as well as the very close approximation of its occurrence.

[0027] In this specification, unless otherwise specified or limited, relative terms such as “central,” “longitudinal,” “lateral,” “front,” “rear,” “right,” “left,” “inner,” “outer,” “lower,” “higher,” “horizontal,” “vertical,” “above,” “below,” “above,” “below,” “top,” “bottom,” and their derivatives (e.g., “horizontally,” “downward,” “upward,” etc.) should be interpreted as referring to the directions described in the discussion or depicted in the accompanying drawings. These relative terms are used for descriptive convenience only and do not require that this application be constructed or operated in a particular orientation.

[0028] For ease of description, "first," "second," "third," etc., can be used in this article to distinguish different components of a figure or a series of figures. "First," "second," "third," etc., are not intended to describe the corresponding components.

[0029] Figure 1 A front view of a secondary battery 100 according to an embodiment of this application is shown. Figure 2 A top view of a secondary battery 100 according to an embodiment of this application is shown. An embodiment of this application provides a secondary battery 100, which includes a housing 10 and a cover plate 30. The housing 10 has an end wall 14 and a side wall 12 forming a cavity, one end of the side wall 12 (… Figure 1 The lower end (shown) is an opening, a cover plate 30 covers the opening and is welded to the side wall 12, and an end wall 14 is disposed at the other end opposite the opening. The secondary battery 100 also includes an electrode assembly 20 housed in a cavity of the housing 10. In some embodiments, the secondary battery 100 is a cylindrical battery.

[0030] The sidewall 12 surrounds the end wall 14. As long as a stable seal and electrical connection can be formed, the connection between the end wall 14 and the sidewall 12 can be achieved in various ways, such as integral stamping, integral casting, or separate welding. The circumference of the sidewall 12 is not limited; it can be cylindrical or prismatic, or it can surround along any other closed-loop contour that matches the end wall 14. In this embodiment, the outer edge of the end wall 14 is circular, and the sidewall 12 is cylindrical, surrounding the outer edge of the end wall 14, with a circular opening formed at the end of the sidewall 12 facing away from the end wall 14. A cavity is formed within the housing 10 formed by the end wall 14 and the sidewall 12 to accommodate the electrode assembly 20, electrolyte, and other necessary battery components. Specifically, the diameter of the housing 10 can be determined according to the specific size of the electrode assembly 20, such as 18mm, 21mm, 46mm, etc. The shell 10 can be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. In order to prevent the shell 10 from rusting during long-term use, a layer of anti-rust material such as metallic nickel can be plated on the surface of the shell 10.

[0031] Figure 3 It shows along Figure 1 A cross-sectional view taken from the BB line. Figure 4 It shows along Figure 2 A cross-sectional view taken from the JJ line. Figure 5 A top view of the manifold 70 and electrode assembly 20 according to an embodiment of this application is shown. Figure 6 It shows along Figure 5 A cross-sectional view taken from the CC line, where compared to Figure 5 Insulating tape 80 is also shown.

[0032] Electrode assembly 20 is a component in the secondary battery 100 where electrochemical reactions occur. The housing 10 may contain one or more electrode assemblies 20. Electrode assembly 20 includes an electrode and a separator, which are wound to form a wound structure. Specifically, in this embodiment, electrode assembly 20 includes a positive electrode, a separator, and a negative electrode wound around an axis of the housing 10.

[0033] See Figure 3 The electrode post (also called electrode terminal) 40 passes through the end wall 14. Along the axial direction A of the housing, a welding area 46 is provided at the end of the electrode post 40 near the opening of the housing 10. The lower plastic 60 is sandwiched between the inner surface of the end wall 14 facing the electrode assembly 20 and the electrode post 40. This application illustrates the lower plastic 60 as a single-piece molded part. In actual implementation, the lower plastic 60 can be a separate part, including a first part sandwiched between the electrode post and the end wall, and a second part sandwiched between the first part and the end wall. The second part is located radially outside the first part. A collector plate 70 is disposed between the electrode post 40 and the electrode assembly 20. The collector plate 70 includes a first partition 71 and a second partition 72 connected radially R along the electrode post 40 to the outside of the first partition 71. The collector plate 70 is a flat plate, also called a flat collector plate.

[0034] The reasons for the gap between the current collector 70 and the electrode post 40 include, for example, when the current collector 70 is welded to the tab of the electrode assembly 20, the heat generated during the welding process causes the current collector 70 to deform thermally, which will cause a gap at the welding position between the current collector 70 and the electrode post 40, resulting in poor welding between the electrode post 40 and the current collector 70, or even problems such as explosion point (due to heat or gap during the welding process, resulting in holes in the molten pool).

[0035] In this embodiment, the lower plastic 60 has a protrusion 62. The protrusion 62 is closer to the electrode assembly 20 than the welding area 46 of the electrode post 40 along the axial direction A of the housing 10. It presses against the second partition 72 in the direction toward the electrode assembly 20, thereby causing the first partition 71 to fit against the welding area 46, and the first partition 71 to weld with the welding area 46 of the electrode post 40. In this embodiment, the collector plate 70 and the protrusion 62 of the lower plastic 60 cooperate. By pressing against the second partition 72 located on the outer ring of the collector plate 70, the first partition 71 at the center of the collector plate 70 tilts upward toward the electrode post 40 to fit snugly against the electrode post 40, preventing the first partition 71 from shifting along the axial direction A toward the cover plate 30, increasing the fit between the first partition 71 of the collector plate 70 and the electrode post 40, and improving the welding yield.

[0036] It is understandable that the tabs of the electrode assembly 20 are usually soft and thin. After they are connected to the collector plate 70, they can be deformed by external pressure. Therefore, by pressing the second partition 72 located on the outer ring of the collector plate 70 with the protrusion 62 of the lower plastic 60, the first partition 71 in the center of the collector plate 70 can be raised toward the pole post 40.

[0037] See Figure 3 Along the axial direction A from the electrode post 40 to the electrode assembly 20, the protrusion height of the protrusion 62 relative to the welding area 46 of the electrode post 40 is h1 mm, where 0.05 ≤ h1 ≤ 0.6. The protrusion height of the protrusion 62 relative to the welding area 46 of the electrode post 40 is ≥0.05 mm, which ensures a good fit between the electrode post 40 and the first partition 71, while avoiding excessive protrusion height (e.g., greater than 0.6). If the protrusion 62 is too high, it will increase the dislocations of the electrode plates near the outer periphery of the electrode assembly 20, and reduce the overhang (OH) of the active material region of the negative electrode plate, leading to a short circuit.

[0038] See Figure 3 and Figure 6 After the current collector 70 and the electrode assembly 20 are electrically connected, first apply insulating tape 80 to the sides of the current collector 70 and the electrode assembly 20, then... Figure 6 The whole shown ( Figure 6 Not indicated: Figure 4 The second current collector 120, connected to the tab at the other end of the middle electrode assembly 20, is inserted into the housing 10, which has been assembled with the electrode post 40, upper plastic 90 (for insulating the electrode post 40 and end wall 14), sealing ring 92 (for sealing the electrode post 40 and end wall 14), and lower plastic 60. In some embodiments, the housing 10 is negatively charged, the current collector 70 is a positive current collector, and is electrically connected (e.g., welded) to the positive electrode tab of the electrode assembly 20. The insulating tape 80 is also referred to as positive electrode protective adhesive. The portion of the insulating tape 80 attached to the electrode assembly 20 allows the electrode assembly 20 and the housing 10 to be insulated. The insulating tape 80 includes a first portion 81 attached to the outer peripheral side of the electrode assembly 20 and a second portion 82 connected to the first portion 81. The second portion 82 extends from the top of the first portion 81 to be attached to the second partition 72, and the protrusion 62 presses the second portion 82 against the surface of the second partition 72 away from the electrode assembly 20. The protrusion 62 can press the second part 82 of the insulating tape 80 together, preventing the insulating tape 80 from falling off due to long-term immersion in the electrolyte inside the housing 10. The insulating tape 80 enhances the insulation between the housing 10 and the electrode assembly 20, and if nickel is deposited in the housing 10, the insulating tape 80 can prevent the deposited nickel dendrites from entering the electrode assembly 20, piercing the diaphragm in the electrode assembly 20, and causing abnormal performance of the electrode assembly 20.

[0039] The current collector 70 is welded to the tabs of the electrode assembly 20 facing the pole post 40 to form a first weld mark 74. A second portion 82 covers at least a portion of the current collector 70 and the first weld mark 74. The width of the second portion 82 in the radial direction R is W1 mm, and the radius of the electrode assembly 20 is W2 mm, 0.1≤W1 / W2≤0.5. The second portion 82 of the insulating tape 80 covers the current collector 70 and at least a portion of the first weld mark 74 between the current collector 70 and the tab, covering foreign matter generated during welding (e.g., weld slag). The first portion 81 of the insulating tape 80 covers the outer periphery of the electrode assembly 20 to ensure insulation between the electrode assembly 20 and the housing 10. When the insulating tape 80 attached to the outer periphery of the electrode assembly 20 is folded towards the upper end face of the electrode assembly 20 and the current collector 70, wrinkles will be generated, with the wrinkles being more severe closer to the axis a. The wrinkles are related not only to the length of the fold (the width of the second part 82 in the radial direction R), but also to the radius of the electrode assembly 20. The smaller the radius, the easier it is to produce wrinkles. 0.1≤W1 / W2≤0.5, to avoid an excessively large ratio (e.g., greater than 0.5). If the second part 82 of the insulating tape 80 has too many folds at the end near the center of the current collector 70, and these folds overlap with the protrusion height of the protrusion 62, it will increase the dislocations of the electrode plates near the outer periphery of the electrode assembly 20. This will reduce the amount of overhang (OH) of the active material region of the negative electrode plate, leading to a short circuit. At the same time, if the ratio is too small (e.g., less than 0.1), the area covered by the second part 82 of the current collector 70 and the first weld mark 74 formed by welding the electrode tabs will be too small, increasing the risk of weld slag falling off. Also, if the portion of the insulating tape 80 pressed by the protrusion 62 of the lower plastic 60 is too small, the insulating tape 80 will easily fall off due to long-term immersion in the electrolyte inside the housing 10.

[0040] See also Figure 3 The distance from the protrusion 62 to the axis a of the pole post 40 is a mm, and the radius of the collector plate 70 is b mm, with 0.6 ≤ a / b ≤ 0.95. The protrusion 62 corresponds to the second section 72 of the outer ring of the collector plate 70, and can exert a downward squeezing force on the second section 72, allowing the first section 71 in the center of the collector plate 70 to tilt upwards and fit against the welding area 46 of the pole post 40. However, if the protrusion 62 is too close to the axis a of the housing 10, it may instead push the first section 71 in the center of the collector plate 70 downwards, resulting in a lower fit between the first section 71 and the welding area 46 of the pole post 40. 0.6≤a / b≤0.95, to avoid the ratio being lower than the lower limit (e.g., lower than 0.6), which would increase the gap between the first partition 71 and the welding area 46 of the pole post 40, and would be detrimental to the fit between the first partition 71 and the welding area 46 of the pole post 40; at the same time, to avoid the ratio being higher than the upper limit (e.g., greater than 0.95), the contact surface between the protrusion 62 and the second partition 72 of the collector plate 70 would be smaller, making it difficult to provide sufficient compressive force.

[0041] Outward along the radial direction R, the outermost edge of the lower plastic 60 extends beyond the outer periphery of the electrode assembly 20. The outermost edge of the lower plastic 60 is closer to the sidewall 12 of the housing 10 than the outer periphery of the electrode assembly 20, thus providing shielding for the electrode assembly 20 and preventing dislocations of the electrode plates near the outer periphery of the electrode assembly 20 from entering the space between the lower plastic 60 and the sidewall 12. In other words, the outermost edge of the lower plastic 60 extends beyond the outer periphery of the electrode assembly 20 to limit or reduce dislocations of the electrode plates near the outer periphery of the electrode assembly 20.

[0042] The tabs of the current collector 70 and the electrode assembly 20 facing the electrode post 40 are welded (e.g., through-welded). The second weld mark 76 formed by welding the electrode post 40 and the first partition 71 (e.g., through-welded) and the first weld mark 74 formed by welding the current collector 70 and the tab are not overlapped and are separated by a distance W3 mm in the radial direction R, where W3 ≥ 0.5. This avoids the second weld mark 76 and the first weld mark 74 overlapping, which would cause heat concentration during welding and result in problems such as weld burn-through and spalling, leading to poor welding.

[0043] The electrode post 40 has a groove 42 with an opening facing away from the collector plate 70. The bottom wall of the groove 42 has an injection hole 48. The bottom wall is a welding area 46, and a second weld mark 76 formed by welding with the first partition 71 is located at the portion where the first partition 71 overlaps with the bottom wall. The electrode assembly 20 is a wound body with a central hole 22. The collector plate 70 has a through hole 78 connecting the injection hole 48 and the central hole 22. The diameter of the through hole 78 is D1 mm, and the diameter of the injection hole 48 is D2 mm, where 0.4 ≤ D2 / D1 ≤ 0.9. (Refer to reference...) Figure 3 and Figure 4 The sealing nail 140 seals the injection hole 48. When assembling the sealing nail 140, it must pass through both the injection hole 48 and the through hole 78. The ratio 0.4 ≤ D2 / D1 ≤ 0.9 is used to avoid an excessively large ratio (e.g., greater than 0.9) affecting the welding area of ​​the manifold 70 and the pole post 40. Simultaneously, the manifold 70 may shift during assembly; if the ratio is too small (e.g., less than 0.4), the manifold 70 will block the injection hole 48, affecting the assembly of the sealing nail 140. In this embodiment, the injection hole 48 and the through hole 78 are coaxially or substantially coaxially arranged.

[0044] The projection of the through hole 78 onto the electrode assembly 20 along the axial direction A falls into the central hole 22. That is, the collector plate 70 blocks the edge of the central hole 22 of the electrode assembly 20. On the one hand, the radius of the through hole 78 of the collector plate 70 is smaller than the radius of the central hole 22, which can ensure that the welding area between the collector plate 70 and the electrode post 40 is as large as possible. On the other hand, the collector plate 70 blocks the edge of the central hole 22 of the electrode assembly 20 and presses the inner ring of the electrode assembly 20, which can prevent the electrode assembly 20 from being pulled up (the electrode sheet wound around the inner ring of the inner ring is pulled up from the through hole 78 of the collector plate 70).

[0045] See Figure 7 This application also provides a battery pack 300, which includes the aforementioned secondary battery 100. In one embodiment of the battery pack 300, the battery pack 300 includes a housing 101, a cover 102, and multiple secondary batteries 100. The multiple secondary batteries 100 are placed in the housing 101 and are connected in series or parallel, or a combination of series and parallel connections. The cover 102 seals the housing 101 to protect the multiple secondary batteries 100. It should be noted that the battery pack 300 may also include a thermal management system, circuit board, etc., in addition to the secondary battery 100. The battery pack 300 can be a battery module, a battery pack, an energy storage cabinet, etc.; these will not be described in detail here.

[0046] See Figure 8 This application also provides an electrical device 1000, which includes the aforementioned battery pack 300. The working part of the electrical device 1000 is connected to the battery pack 300 to obtain electrical power. As an example, the electrical device 1000 is a vehicle, which can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc., but are not limited thereto. The battery pack 30 is, for example, located at the bottom of the vehicle 1001 and provides electrical power for the vehicle's operation or the operation of electrical components within the vehicle. However, in some other embodiments, the electrical device 1000 can also be a mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, and power tool, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; the working part can be a unit component capable of obtaining electrical power from the battery pack 300 and performing corresponding work, such as a fan blade rotation unit or a vacuum cleaner suction unit. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric boat toys, and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the aforementioned electrical device 1000.

[0047] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A secondary battery, characterized in that, include: The housing has an opening at one end and an end wall at the other end opposite to the opening; A pole post is inserted through the end wall, and a welding area is provided at the end of the pole post near the opening along the axial direction of the housing; Electrode assemblies are disposed within the housing; The lower plastic is clamped between the inner surface of the end wall facing the electrode assembly and the electrode post; A current collector is disposed between the electrode post and the electrode assembly. The current collector includes a first partition and a second partition, with the second partition connected to the outside of the first partition along the radial direction of the housing. The lower plastic part has a protrusion that is closer to the electrode assembly in the axial direction than the welding area of ​​the pole post. The protrusion presses against the second partition in the direction toward the electrode assembly, thereby causing the first partition to fit into the welding area and the first partition to be welded to the welding area.

2. The secondary battery according to claim 1, characterized in that, Also includes: The insulating tape includes a first portion adhered to the outer periphery of the electrode assembly and a second portion connected to the first portion, the second portion being adhered to a second partition, and the protrusion pressing the second portion against the surface of the second partition away from the electrode assembly.

3. The secondary battery according to claim 1, characterized in that, Along the axial direction from the pole post to the electrode assembly, the protrusion height of the protrusion relative to the welding area of ​​the pole post is h1 mm, 0.05≤h1≤0.

6.

4. The secondary battery according to claim 1, characterized in that, The distance from the protrusion to the axis of the housing is a mm, the radius of the collector plate is b mm, and 0.6 ≤ a / b ≤ 0.

95.

5. The secondary battery according to claim 1, characterized in that, Outward along the radial direction, the outermost edge of the lower plastic extends beyond the outer periphery of the electrode assembly.

6. The secondary battery according to claim 2, characterized in that, The current collector is welded to the tab of the electrode assembly facing the pole to form a first weld mark. The second part covers at least a portion of the current collector and the first weld mark. The width of the second part in the radial direction is W1 mm. The radius of the electrode assembly is W2 mm. 0.1≤W1 / W2≤0.

5.

7. The secondary battery according to claim 1, characterized in that, The current collector is welded to the tabs of the electrode assembly facing the pole to form a first weld mark, and the welding area of ​​the pole and the first partition are welded to form a second weld mark. The first weld mark and the second weld mark do not overlap and are separated by a distance ≥0.5mm in the radial direction.

8. The secondary battery according to claim 1, characterized in that, The electrode post has a groove with an opening facing away from the collector plate. The bottom wall of the groove has a liquid injection hole. The bottom wall is the welding area and is welded to the first partition to form a second weld mark. The electrode assembly is a wound body with a central hole. The manifold has a through hole connecting the injection hole and the central hole. The diameter of the through hole is D1 mm, and the diameter of the injection hole is D2 mm, where 0.4 ≤ D2 / D1 ≤ 0.

9. The sealing nail seals the injection hole and passes through the through hole.

9. The secondary battery according to claim 8, characterized in that, The projection of the through hole onto the electrode assembly along the axial direction falls into the central hole.

10. A battery pack, characterized in that, The battery pack includes a secondary battery as described in any one of claims 1 to 9.

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