Secondary battery, battery pack, and electric device

Abstract

A secondary battery, an electrode terminal includes a penetrating portion passing through a mounting hole, a first fixing portion and a second fixing portion provided on the inner side and the outer side of an end wall in the axial direction; a seal surrounds the penetrating portion and is at least partially pressed between the first fixing portion and the end wall; a first insulating member surrounds the seal and is at least partially clamped between the first fixing portion and the end wall; a second insulating member surrounds the penetrating portion, the second fixing portion and the end wall are riveted, and at least part of the second insulating member is pressed between the second fixing portion and the end wall, the second insulating member includes a glue inlet and a fusion mark separated from the glue inlet in the circumferential direction of the second insulating member, and the second insulating member further includes a first groove avoiding the glue inlet and the fusion mark in the circumferential direction. The utility model aims at providing a secondary battery, a battery pack and an electric device, so as to improve the sealing property of the secondary battery at least.

Description

Technical Field

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

[0002] In secondary batteries, an insulating component is placed between the electrode terminals and the end walls of the casing to insulate both. As the performance of secondary batteries continues to improve, the requirements for their sealing performance are also increasing. Currently, there is room for improvement in the sealing performance between the electrode terminals and the end walls of existing secondary batteries. 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, battery pack and power device to at least improve the sealing performance of the secondary battery.

[0004] To achieve the above objectives, this utility model provides a secondary battery, comprising: a housing having an opening at one end in its axial direction and an end wall at the other end opposite to the opening, the end wall having a mounting hole; an electrode assembly disposed within the housing; an electrode terminal fixed to the end wall and electrically connected to the electrode assembly, the electrode terminal including a through portion passing through the mounting hole, and a first fixing portion and a second fixing portion disposed on the inner and outer sides of the end wall in its axial direction; a sealing member surrounding the through portion and at least partially pressed between the first fixing portion and the end wall; a first insulating member surrounding the sealing member and at least partially clamped between the first fixing portion and the end wall; and a second insulating member surrounding the through portion, the second fixing portion being riveted to the end wall and at least a portion of the second insulating member being pressed between the second fixing portion and the end wall, the second insulating member including an inlet and a weld line spaced apart from the inlet in the circumferential direction of the second insulating member, the second insulating member further including a first groove that avoids the inlet and the weld line in the circumferential direction.

[0005] The beneficial technical effect of this application is that: in the embodiments of this application, the second fixing part and the end wall are riveted together, at least a part of the second insulating member is squeezed, and the first groove avoids the glue inlet in the circumferential direction of the second insulating member, so as to avoid the first groove and the glue inlet coinciding and affecting the sealing effect of the interface between the second insulating member and the electrode terminal and the end wall. Furthermore, the second insulating component has low strength at the weld line. The weld line is the interface where molten plastic meets in the circumferential direction C during injection molding of the second insulating component. Compared to the non-interface area, the weld line is squeezed out, resulting in poor sealing between the second insulating component and the end wall and the second fixing part at the weld line location. In this embodiment, the first groove avoids the weld line in the circumferential direction to prevent the two from overlapping and further damaging the sealing between the second insulating component and the end wall and the second fixing part. It also prevents the strength of the second insulating component from being further reduced due to the overlap of the first groove and the weld line, which could lead to the second insulating component being crushed when squeezed by the second fixing part and the end wall. This ensures the structural strength of the second insulating component and improves the sealing reliability of the secondary battery at the interface between the second insulating component and the electrode terminals and the end wall.

[0006] In some embodiments, the inlet and the first groove are located on the same surface of the second insulating member perpendicular to the axial direction.

[0007] In some embodiments, the number of the first grooves is n, n≥2, and the n first grooves are equidistantly distributed along the circumference of the second insulating member.

[0008] In some embodiments, the same surface faces the outer side of the end wall, and the insulating member further includes a glue inlet, the glue inlet being disposed within the glue inlet.

[0009] In some embodiments, the depth of the injection port is H mm, the depth of the first groove is h mm, and 0.7 ≤ H / h ≤ 1.3.

[0010] In some embodiments, the second insulating member further includes a portion surrounding the outer edge of the electrode terminal and a portion located between the through portion and the end wall.

[0011] In some embodiments, the first insulating member includes a second groove located on the side of the first insulating member facing the end wall or the first fixing portion, and the second groove is exposed on the side of the first insulating member facing the seal.

[0012] In some embodiments, the first groove and / or the second groove are used for helium detection to determine whether the seal is missing.

[0013] An embodiment of this application also provides a battery pack, including any of the above-mentioned secondary batteries and a busbar, wherein the busbar is connected in series or in parallel to the electrode terminals of the secondary batteries, and the second insulating member is made of soluble polytetrafluoroethylene.

[0014] Embodiments of this application also provide an electrical device including the aforementioned battery pack. 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 1 A schematic diagram is shown when the electrical device in an embodiment of this application is a vehicle.

[0017] Figure 2 A battery pack according to an embodiment of this application is shown.

[0018] Figure 3 A top view of a secondary battery according to a first embodiment of this application is shown.

[0019] Figure 4 It shows along Figure 3 A cross-sectional view taken from the VV line.

[0020] Figure 5 It shows Figure 4 A magnified view of region J in the middle.

[0021] Figure 6 It shows Figure 4 Enlarged cross-sectional view of region K in the middle.

[0022] Figure 7 It shows Figure 6 A magnified view of the L region.

[0023] Figure 8 Another cross-sectional view of a secondary battery according to a first embodiment of this application is shown.

[0024] Figure 9 It shows Figure 8 A magnified view of region M in the middle.

[0025] Figure 10A top perspective view (isometric view) of a first insulating member according to a first embodiment of this application is shown.

[0026] Figure 11 A bottom perspective view of the second insulating member according to the first embodiment of this application is shown.

[0027] Figure 12 It shows Figure 11 A magnified view of the S-region.

[0028] Figure 13 A bottom view of the second insulating member according to the first embodiment of this application is shown.

[0029] Figure 14 It shows along Figure 13 A cross-sectional view taken from the NN line.

[0030] Figure 15 It shows Figure 14 A magnified view of the U-region.

[0031] Figure 16 It shows along Figure 13 A cross-sectional view taken from the OO line.

[0032] Figure 17 A top view of the second insulating member according to the first embodiment of this application is shown.

[0033] Figure 18 It shows along Figure 17 A cross-sectional view taken from the PP line.

[0034] Figure 19 It shows Figure 18 A magnified view of the Q region.

[0035] Figure 20 A top view of a secondary battery according to a second embodiment of this application is shown.

[0036] Figure 21 It shows along Figure 20 A sectional view taken from the BB line.

[0037] Figure 22 It shows Figure 21 A magnified view of region E in the middle.

[0038] Figure 23 It shows Figure 21 Enlarged cross-sectional view of region F in the middle.

[0039] Figure 24 It shows Figure 21 Enlarged cross-sectional view of region G in the middle.

[0040] Figure 25A top perspective view of the first insulating member according to a second embodiment of this application is shown.

[0041] Figure 26 A bottom perspective view of the first insulating member according to a second embodiment of this application is shown.

[0042] Figure 27 A bottom view of the first insulating member according to a second embodiment of this application is shown.

[0043] Figure 28 A top view of the first insulating member according to a second embodiment of this application is shown.

[0044] Figure 29 It shows along Figure 28 A cross-sectional view taken from the TT line.

[0045] Figure 30 It shows Figure 29 A magnified view of region I in the middle.

[0046] Figure 31 This is a schematic diagram of the electrode assembly of an example of the secondary battery of the present invention. Detailed Implementation

[0047] To better understand the spirit of the embodiments of this application, the following description is based on some preferred embodiments of this application.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] See Figure 1 This application provides an electrical device 1000, which includes a 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 300 is, for example, located at the bottom of the vehicle body 1001 and provides electrical power for the vehicle's operation or the operation of electrical components within the vehicle. However, in 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 is a unit component capable of obtaining electrical power from the battery pack 300 and performing corresponding work, such as the fan blade rotation unit of a fan, the vacuuming unit of a vacuum cleaner, etc. 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.

[0053] See Figure 2 This application also provides a battery pack 300, which includes secondary batteries 100 and busbars. 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 in parallel, or a combination of series and parallel connections. The busbars are connected in series or in parallel to the electrode terminals 40 of the secondary batteries 100. The cover 102 covers the housing 101 to protect the multiple secondary batteries 100. It should be noted that the secondary batteries 100 in this application are single cells. It should also be noted that the battery pack 300 may include a thermal management system, circuit boards, etc., in addition to the secondary batteries 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.

[0054] Figure 3 A top view of a secondary battery 100 according to a first embodiment of this application is shown. Figure 4 It shows along Figure 3 A cross-sectional view taken from the VV line. Figure 5 It shows Figure 4 Enlarged view of region J, where the positive current collector 141 and electrode assembly 120 are not shown. Figure 6It shows Figure 4 Enlarged cross-sectional view of region K, where the sealing pin 47, positive current collector 141 and electrode assembly 120 are not shown. Figure 7 It shows Figure 6 A magnified view of the L region.

[0055] Figure 8 Another cross-sectional view of a secondary battery 100 according to a first embodiment of this application is shown. Figure 9 It shows Figure 8 A magnified view of region M in the middle. (The image was captured.) Figure 8 The face of the sectional view shown is... Figure 4 Different, among them Figure 8 We cut to the 74mm inlet.

[0056] Figure 10 A top perspective view (isometric view) of the first insulating member 71 according to the first embodiment of this application is shown. Figure 11 A bottom perspective view of the second insulating member 72 according to the first embodiment of this application is shown. Figure 12 It shows Figure 11 A magnified view of the S-region.

[0057] Figure 13 A bottom view of the second insulating member 72 according to the first embodiment of this application is shown. Figure 14 It shows along Figure 13 A cross-sectional view taken from the NN line. Figure 15 It shows Figure 14 A magnified view of the U-region. Figure 16 It shows along Figure 13 A cross-sectional view taken from the OO line. Figure 17 A top view of the second insulating member 72 according to the first embodiment of this application is shown. Figure 18 It shows along Figure 17 A cross-sectional view taken from the PP line. Figure 19 It shows Figure 18 A magnified view of the Q region.

[0058] Figure 20 A top view of a secondary battery 100 according to a second embodiment of this application is shown. Figure 21 It shows along Figure 20 A sectional view taken from the BB line. Figure 22 It shows Figure 21 A magnified view of region E in the middle. Figure 23 It shows Figure 21 Enlarged cross-sectional view of region F in the middle, where sealing nail 47 is not shown. Figure 24 It shows Figure 21 Enlarged cross-sectional view of region G, where sealing nail 47 is not shown.

[0059] Figure 25 A top perspective view of the first insulating member 71 according to the second embodiment of this application is shown. Figure 26 A bottom perspective view of the first insulating member 71 according to the second embodiment of this application is shown. Figure 27 A bottom view of the first insulating member 71 according to the second embodiment of this application is shown. Figure 28 A top view of the first insulating member 71 according to the second embodiment of this application is shown. Figure 29 It shows along Figure 28 A cross-sectional view taken from the TT line. Figure 30 It shows Figure 29 A magnified view of region I in the middle.

[0060] 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. The housing 10 is located at one end in its axial direction A. Figure 4 The lower end shown is an opening, and the end wall 14 is located at the other end opposite to the opening.

[0061] 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 follow 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 120, 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 120, such as 18mm, 21mm, or 46mm. The shell 10 can be made of various materials, such as copper, iron, aluminum, steel with nickel layer, 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.

[0062] Figure 31 This is a schematic diagram of the electrode assembly 120 of an example of the secondary battery 100 of this utility model. The electrode assembly 120 is disposed inside the housing 10 and is a component in the secondary battery 100 where electrochemical reactions occur. The housing 10 may contain one or more electrode assemblies 120. The electrode assembly 120 includes an electrode sheet and a separator 122, which are wound to form a wound structure. Specifically, in this embodiment, the electrode assembly 120 includes a positive electrode sheet 121, a separator 122, and a negative electrode sheet 123 wound around the housing 10 axially.

[0063] The positive electrode 121 includes a positive current collector 1211 and a positive active material layer coated on the positive current collector 1211. A first coated area 1212 coated with the positive active material layer and a first uncoated area 1213 uncoated with the positive active material layer are formed on the positive current collector 1211. The first coated area 1212 and the first uncoated area 1213 are arranged along the axial direction A of the housing 10. The first uncoated area 1213 extends to one end of the secondary battery 100 in the height direction to the outside of the separator 122 and is bent towards the axis of the housing 10 to form a stacked positive electrode tab 125.

[0064] The negative electrode 123 includes a negative current collector 1231 and a negative active material layer coated on the negative current collector 1231. A second coated area 1232 coated with the negative active material layer and a second uncoated area 1233 uncoated with the negative active material layer are formed on the negative current collector 1231. The second coated area 1232 and the second uncoated area 1233 are arranged along the axial direction of the housing 10. The second uncoated area 1233 extends to the other end of the secondary battery 100 in the height direction to the outside of the separator 122 and is bent towards the axis of the housing 10 to form a stacked negative electrode tab 124.

[0065] A separator 122 is disposed between the positive electrode 121 and the negative electrode 123 to isolate the positive and negative active material layers. Taking a lithium-ion secondary battery 100 as an example, the positive current collector 1211 can be made of aluminum, and the positive active material layer includes positive active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative current collector 1231 can be made of copper, and the negative active material layer includes negative active material, which can be carbon or silicon, etc. The substrate material of the separator 122 can be polypropylene (PP) or polyethylene (PE), etc. To protect and insulate the battery cell, an insulating film can also be wrapped around the outside of the battery cell. The insulating film can be synthesized from PP, PE, polyethylene terephthalate (PET), polyvinyl chloride (PVC), or other polymer materials.

[0066] In this embodiment, the secondary battery 100 further includes a cover plate 30, which is sealed to the opening (e.g., by welding the cover plate 30 to the side wall 12). Electrode terminals 40 are fixed to the end wall 14 and electrically connected to the electrode assembly; electrode terminals 40 can also be referred to as terminals. In this invention, the positive electrode tab 125 faces the end wall 14 or the opening of the housing 10, while the negative electrode tab 124 faces the other end of the housing 10. In this embodiment, the positive electrode tab 125 faces the end wall 14 and is electrically connected to the electrode terminal 40 via the positive current collector 141, making the electrode terminal 40 positively charged. The negative electrode tab 124 faces the opening, and the housing 10 is electrically connected to the negative electrode tab 124 via the negative current collector 142, thus making it negatively charged. However, in another embodiment, the negative electrode tab 124 can be connected to the electrode terminal 40, and the positive electrode tab 125 can be connected to the housing 10.

[0067] The electrode terminal 40 includes a through portion 44 that passes through a mounting hole in the end wall 14, and a first fixing portion 41 and a second fixing portion 42 disposed on the inner and outer sides of the end wall 14 in the axial direction A. An insulating member 70 surrounds the through portion 44 and is at least partially clamped between the first fixing portion 41 and the end wall 14, and / or at least partially clamped between the second fixing portion 42 and the end wall 14.

[0068] The first fixing part 41 is disposed inside the housing 10, and the second fixing part 42 is disposed outside the housing 10. The insulating member 70 includes a first insulating member 71 disposed inside the housing 10 and a second insulating member 72 disposed outside the housing 10. The first insulating member 71 is at least partially clamped between the first fixing part 41 and the end wall 14, and the second insulating member 72 is at least partially clamped between the second fixing part 42 and the end wall 14. The insulating member 70 provides electrical insulation between the electrode terminal 40 and the end wall 14 of the housing 10. In some embodiments, the first insulating member 71 and the second insulating member 72 may also be referred to as the lower plastic and the upper plastic, respectively.

[0069] To prevent electrolyte leakage through the mounting hole to the outside of the secondary battery 100 and causing a safety accident, a seal 90 is generally installed inside the mounting hole to seal the electrode terminal 40 and the end wall 14. The seal 90 is arranged around the through portion 44 of the electrode terminal 40, and at least a portion of the seal 90 is clamped and compressed between the first fixing portion 41 and the end wall 14. A first insulating member 71 is arranged radially R along the outside of the seal. The seal 90 can also be called a sealing ring, and it is the component that plays a major sealing role between the electrode terminal 40 and the end wall 14. The material of the seal 90 is, for example, fluororubber.

[0070] After the secondary battery 100 is assembled, it is generally necessary to test its sealing performance. The commonly used testing method is helium leak detection (referred to as helium test). Helium leak detection is a sealing test method that uses helium as a leak indicator gas. During helium leak detection, the secondary battery 100 is first placed in a vacuum-sealed test chamber, and after the internal vacuum of the secondary battery 100 is evacuated, helium is injected. Then, a helium detector is used to detect the amount of helium leaked from the secondary battery 100 into the vacuum-sealed test chamber to determine the sealing performance of the secondary battery 100.

[0071] When testing the sealing performance of the secondary battery 100, some secondary batteries 100 that passed the sealing test still showed leakage after a period of use. The accuracy of the sealing performance test results for the secondary battery 100 is relatively low.

[0072] Research has revealed that when the seal 90 fails (e.g., the seal 90 is missing, making it difficult to detect by observation as it is not located on the surface of the housing 10), the insulating component 70 provides a certain degree of sealing, which can easily lead to a false seal in the secondary battery 100 (i.e., because the seal 90 is not effectively sealing). During the sealing test of the secondary battery 100, since the secondary battery 100 is not under actual operating conditions, the aforementioned false seal phenomenon allows the secondary battery 100 to meet the sealing test requirements, but it cannot meet the needs of actual operating conditions. For example, under certain conditions, when the gas pressure increases after internal circulation in the secondary battery 100, the absence of the seal 90 causes sealing failure.

[0073] Therefore, to improve the accuracy of the sealing test results of the secondary battery 100, the second insulating member 72 includes a first groove 728 connecting the exterior of the secondary battery 100 and the mounting hole, so that the exterior of the secondary battery 100 is connected to the interior of the housing 10 when the sealing member 90 fails. When testing the sealing of the secondary battery 100, if the sealing member 90 fails, the exterior of the secondary battery 100 and the interior of the housing 10 can be connected through the first groove 728. The helium gas filled into the secondary battery 100 can flow to the exterior of the secondary battery 100 through the first groove 728, causing an abnormal amount of helium gas detected by the helium detector. This reduces the interference of false sealing on the test results and improves the accuracy of the sealing test results of the secondary battery 100.

[0074] See Figure 5 , Figure 6 and Figure 9In the first embodiment of this application, the electrode terminal 40 is externally riveted, and the second fixing part 42 located outside the housing 10 is the riveting part. The second fixing part 42 of the electrode terminal 40 originally extends parallel to the axial direction A, that is, it is vertical. The second fixing part 42 passes through the mounting hole of the end wall 14 from the inside of the housing 10 outward. By flanging or pressing the second fixing part 42, the second fixing part 42 is made to extend radially R beyond the mounting hole of the end wall 14 and bend toward the end wall 14, and the second insulating member 72 is squeezed (see Figure 9 ).

[0075] For example, see Figure 11 and Figure 14 When the second insulating part 72 is formed by injection molding, the molten plastic slurry enters the mold through the sprue of the mold for the second insulating part 72. Therefore, the sprue 74 is the structure formed on the solidified second insulating part 72 by the sprue of the mold after demolding. The liquid molten plastic slurry flows from the sprue 74 along the circumferential direction C of the second insulating part 72 to both sides of the sprue 74. If the number of sprues 74 is 1, they converge at the symmetrical position of the sprues 74 about the axial direction A to form a weld line 75. If the number of sprues 74 distributed along the circumferential direction C is N, and N≥2, then the number of weld lines 75 is also N, and a weld line is formed in the middle of every two adjacent sprues 74 along the circumferential direction C.

[0076] See Figures 22 to 24 In the second embodiment of this application, the electrode terminal 40 is internally riveted, and the first fixing part 41 located inside the housing 10 is the riveting part. The first fixing part 41 of the electrode terminal 40 originally extends parallel to the axial direction A, that is, it is vertical. The first fixing part 41 is inserted into the mounting hole of the end wall 14 from the outside of the housing 10. By expanding or pressing the first fixing part 41, the first fixing part 41 extends beyond the mounting hole of the end wall 14 in the radial direction R and bends toward the end wall 14, and the first insulating member 71 is squeezed.

[0077] For example, see Figure 30 When the first insulating part 71 is injection molded, the molten plastic slurry enters the mold through the sprue of the first insulating part 71. Therefore, the sprue 74 is a structure formed on the cured first insulating part 71 by the sprue of the mold after demolding. See, for example. Figure 27 The liquid molten plastic slurry flows along the circumferential direction C to both sides of the inlet 74. If the number of inlets 74 is 1, they converge at the symmetrical position of the inlets 74 about the axial direction A to form a weld line 75. If the number of inlets 74 distributed along the circumferential direction C is N, and N≥2, then the number of weld lines 75 is also N, and a weld line 75 is formed in the middle of every two adjacent inlets 74 along the circumferential direction C.

[0078] Commonly used plastic materials include soluble polytetrafluoroethylene (PFA), polypropylene (PP), and polybutylene terephthalate (PBT). PFA has a melting point of approximately 310℃; its melt flow index (MFR, tested according to ISO R1133) is greater than or equal to 9 g / 10 min, for example, it includes two specifications: 14 g / 10 min and 30 g / 10 min; its yield strength is 10-20 MPa, and it has good thermal stability. PP has an MFR of 8.0 g / 10 min; its melting point is approximately 164-170℃; and its yield strength is 25-40 MPa. PBT has a melting point of approximately 225-275℃; compared to PFA, it has poorer thermal stability. Comparing the three materials, PFA exhibits better high-temperature resistance, crack resistance, resilience, and corrosion resistance.

[0079] In this embodiment, the portion of the insulating member 70 at the riveting location uses PFA material because PFA has low yield strength and better elasticity, thus providing a certain sealing performance. Compared to PFA, PP plastics are more brittle and prone to plastic deformation. When compressed by the electrode terminal 40, PP material is prone to cracking, affecting the sealing performance. Therefore, in the first embodiment, the material of the second insulating member 72 compressed by the second fixing part 42 is preferably PFA; in the second embodiment, the material of the first insulating member 71 compressed by the first fixing part 41 is preferably PFA, which is beneficial to the sealing effect at the electrode terminal 40.

[0080] See Figure 4 In some embodiments, the electrode terminal 40 is electrically connected to the electrode assembly via a positive current collector 141. For example, the positive current collector 141 is welded to the positive electrode tab of the electrode assembly, and then the electrode terminal 40 and the positive current collector 141 are welded from the outside of the housing 10 via through-welding. See also Figure 4 and Figure 5 A groove 46 is formed on the electrode terminal 40. The bottom wall of the groove 46 is welded to the positive current collector 141. The thinned part of the electrode terminal 40 is used for welding to the positive current collector 141, which improves the situation of thick welding thinning when penetrating from the outside, reduces welding difficulty, and avoids excessive welding temperature from burning the diaphragm in the electrode assembly. The electrode terminal 40 also includes a sealing pin 47 (see Figure 5 and Figure 22 The sealing pin 47 is welded to the opening of the groove 46 to seal the groove 46. Heat is generated during welding, therefore the material of the second insulating member 72, which is closer to the weld pool 49, needs to be heat-resistant. Additionally, heat is also generated when welding the electrode terminals 40 and busbars of the multiple secondary batteries 100 together.

[0081] In the first embodiment where the electrode terminal 40 is externally riveted, the external second insulating member 72 is preferably made of PFA material, which can withstand high temperatures and also provide partial sealing. The internal first insulating member 71, which does not require high temperature resistance and sealing, can be made of PP material or PFA material, preferably PP material, to reduce costs.

[0082] In the second embodiment where the electrode terminal 40 is riveted internally, the external second insulating member 72 is preferably made of PFA material to withstand high temperatures; the internal first insulating member 71 is preferably made of PFA material to provide partial sealing.

[0083] In summary, the electrode terminal 40 is riveted to the end wall 14 by the first fixing part 41 or the second fixing part 42 to compress the insulating part 70, which is made of PFA. Compared with other plastic materials (such as PP, PPS, etc.), PFA has better elasticity. The first fixing part 41 or the second fixing part 42 compresses the insulating part 70 to increase the contact between the insulating part 70, the housing 10 and the electrode terminal 40, thereby achieving a certain sealing effect at the interface between the insulating part 70 and the electrode terminal 40 and the housing 10. At the same time, PFA has a high melting point and good heat resistance, preventing the surrounding heat from affecting its sealing performance.

[0084] In the injection molding process of PFA materials, the shear rate of the molten plastic slurry represents the rate of velocity change between adjacent fluid layers during melt flow. When the melt passes through narrow runners or gates, the flow velocity difference between the outer and central layers is significant, creating a shearing effect, at which point the shear rate reaches a high value. Therefore, the shear rate is an important parameter describing the internal velocity gradient of the molten material flowing in the runner and cavity. It directly affects the material's flowability, viscosity, and the quality of the final product.

[0085] In the injection molding process of PFA material, the phenomenon of adjacent fluid layers during melt flow is a typical characteristic of laminar flow. During injection molding, the molten PFA material flows in a laminar state. The characteristics of laminar flow are that the fluid flows in parallel layers with no lateral mixing between layers; motion is transmitted only through shear stress. The velocity distribution of the flow layers is as follows: for the flow layer close to the mold wall, due to the adsorption of plastic molecules to the mold wall, the velocity of the flow layer close to the wall is the minimum (boundary layer effect); for the central flow layer, the velocity of the flow layer far from the wall is the maximum, forming a parabolic velocity gradient, i.e., a distribution that is fast in the middle and slow on both sides; for the relative sliding of adjacent flow layers, the velocity difference generated by the shear stress creates interlayer frictional resistance, hindering the overall flow. For circular tubes or cavities, taking a cylindrical flow channel as an example, the radial velocity distribution R is parabolic, with the highest velocity at the center and zero at the wall. For mold cavities or flow channels with non-circular cross-sections (such as rectangular or irregular cavities), the flow layer still follows the rule of "fast at the center and slow at the edge", but the velocity gradient may vary depending on the cross-sectional shape.

[0086] PFA materials have a melt flow index greater than or equal to 9 g / 10 min. Compared to materials with a lower melt flow index (such as PP), they have a faster flow rate, resulting in different shear stresses at the flow channel edges and center, and a large flow rate difference, which leads to the aforementioned stratification phenomenon. Therefore, in applications such as... Figure 19 and Figure 30 On the cross-section shown (which also corresponds to the cross-section of the mold cavity or runner), the melt is divided into multiple parallel thin layers (flow layers), each with a different flow velocity, creating a stratification region 79 (manifested as a gap) along the axial direction A. The stratification region 79 can be observed, for example, using a 4K resolution testing device like the Phoenix Vltomelx M300. Specific reasons for the formation of the stratification region 79 include: wall adhesion, where the flow layer adhering closely to the mold wall becomes stationary due to adhesion, forming a low-velocity boundary layer; shear stress transmission, where the high-speed movement of the central flow layer drives adjacent flow layers through shear stress, creating a gradient velocity distribution; and viscosity influence, where higher dynamic viscosity results in greater interlayer shear stress and more pronounced stratification. The stratification region 79 is parallel to the material flow direction. The tensile strength of the insulating component 70 decreases due to the formation of the stratification region 79. The tensile strength of the insulating component 70 without the formation of the stratification region 79 is approximately 10-25 MPa; after the formation of the stratification region 79, the tensile strength may decrease by 50%.

[0087] For the insulating component 70, the factors affecting the sealing performance at the electrode terminal 40 include: the sealing performance of the interface between the insulating component 70 and the end wall 14 during riveting, and the sealing performance of the material of the insulating component 70 itself.

[0088] For example, see Figures 13 to 16Since the weld line 75 is formed by the fusion of two fluids, the strength of the insulating component 70 is lower at the location of the weld line 75. The number of weld lines 75 is controlled to ensure the overall strength of the insulating component 70. In this embodiment, the maximum outer diameter of the insulating component 70 along the radial R direction of the housing 10 is D mm, and the number N of weld lines 75 is the integer part of the remainder of D / 6. In this embodiment, Figure 14 The maximum outer diameter of the second insulating element 72 shown is 18-20 mm; Figure 29 The maximum outer diameter of the first insulating member 71 shown is 18-22 mm. In the embodiments of this application, the first insulating member 71 and the second insulating member 72 each include, for example, three glue inlets 74, and correspondingly, each also has three weld lines 75.

[0089] In this embodiment, a first groove 728 is provided on the second insulating member 72 to allow communication between the exterior of the secondary battery 100 and the interior of the housing 10 when the seal 90 fails (e.g., the seal 90 is missing). This improves the accuracy of the sealing test results and allows for timely detection of poor sealing of the secondary battery 100 caused by the failure of the seal 90, thereby improving the long-term reliability of the secondary battery 100. Furthermore, the injection port 74 and the first groove 728 are prepared together during the injection molding of the second insulating member 72. The mold for forming the first groove 728 and the die head for forming the injection port 74 are staggered, so the position of the first groove 728 avoids the injection port 74.

[0090] In the embodiments of this application, the second fixing part 42 and the end wall 14 are riveted together, pressing at least a portion of the second insulating member 72. The first groove 728 avoids the glue inlet 74 on the circumferential C of the second insulating member 72, so as to avoid the first groove 728 and the glue inlet 74 from overlapping and affecting the sealing effect of the interface between the second insulating member 72 and the electrode terminal 40 and the end wall 14. Furthermore, the second insulating member 72 has low strength at the weld line 75. The weld line 75 is the interface where molten plastic meets in the circumferential direction C during the injection molding of the second insulating member 72. Compared to the non-interface area, the weld line 75 is squeezed, resulting in poor sealing of the interface between the second insulating member 72 and the end wall 14 and the second fixing part 42 at the weld line 75 position. In this embodiment, the first groove 728 avoids the weld line 75 in the circumferential direction C to prevent the two from overlapping and further damaging the sealing of the interface between the second insulating member 72 and the end wall 14 and the second fixing part 42. It also avoids further reducing the strength of the second insulating member 72 due to the overlap of the first groove 728 and the weld line 75, which would cause the second insulating member 72 to be crushed when squeezed by the second fixing part 42 and the end wall 14. This ensures the structural strength of the second insulating member 72 and improves the sealing reliability of the interface between the secondary battery 100 and the second insulating member 72 and the electrode terminal 40 and the end wall 14.

[0091] See also Figure 13 The number of first grooves 728 is n, where n ≥ 2. These n first grooves 728 are disposed on the same surface of the second insulating member 72 perpendicular to the axial direction A, and are equidistantly distributed along the circumferential direction C of the second insulating member 72 to ensure more uniform stress distribution on the compressed second insulating member 72. When n is even, the n first grooves 728 are symmetrical about the central axis of the second insulating member 72 to ensure symmetrical stress distribution on the compressed second insulating member 72, thereby improving the reliability of the second insulating member 72. In some embodiments, the number of first grooves 728, n = 2, 3, or 4, etc.

[0092] See Figures 13 to 16 The insulating component 70 (second insulating component 72) also includes N injection ports 76 (used to assist in fixing the injection mold head during injection molding). N inlet ports 74 are correspondingly arranged within the N injection ports 76, and the injection ports 76 are located on the outer surface 77 of the second insulating component 72 facing the end wall 14. The injection port 76 is a recessed groove from the surface 77 to assist in accurately positioning and matching the injection mold head with the inlet port 74. The diameter of the injection port 76 is larger than that of the inlet port 74. The injection ports 76 and the first groove 728 facing the end wall 14 can be identified by a CCD camera to determine whether the second insulating component 72 is installed backwards, thus achieving foolproof installation of the second insulating component 72. Furthermore, the injection ports 76 and the first groove 728 are not visible from the outside of the secondary battery 100, making the appearance of the secondary battery 100 more complete.

[0093] The injection port 74 and the first groove 728 are located on the same surface 77 of the second insulating member 72 perpendicular to the axial direction A. During injection molding of the second insulating member 72, the mold for forming the first groove 728 and the die head for forming the injection port 74 can be located on the same side of the second insulating member 72. Since both the injection port 74 and the first groove 728 are relatively weak parts of the second insulating member 72, uniformly placing these weak parts along the circumferential direction C on the same surface 77 of the second insulating member 72 helps to make the thickness distribution of the second insulating member 72 as consistent as possible, thereby improving the reliability of the second insulating member 72.

[0094] Furthermore, the depth of the injection port 76 is H mm, and the depth of the first groove 728 is h mm, where 0.7 ≤ H / h ≤ 1.3. The close proximity of the depths of the injection port 76 and the first groove 728 ensures a more uniform force distribution on the second insulating component 72 in the circumferential direction C when it is pressed by the second fixing part 42, thus improving the sealing performance of the second insulating component 72. After injection molding and material curing, due to the adhesive properties of the colloid, stringing (outward protrusion) will occur at the injection port 74 when the insulating component 70 is pulled out of the mold. The depth of the injection port 76 is controlled within the range of 0.1 mm to 0.4 mm to accommodate the protrusion caused by stringing. The depths of the injection port 76 and the first groove 728 cannot be too large (e.g., greater than 0.4 mm) to avoid affecting the overall strength of the insulating component 70.

[0095] See Figure 15 In the embodiment of external riveting, the second fixing part 42 is a riveting flange structure, the second insulating member 72 includes an outer edge 722 surrounding the outer edge of the electrode terminal 40 and an inner edge 724 located between the through part 44 and the end wall 14, the glue inlet 74 and the first groove 728 are located in the portion 726 of the second insulating member 72 that is clamped between the second fixing part 42 and the end wall 14, and are located on the side of the second insulating member 72 facing the end wall 14. The inner edge 724 located between the through-hole 44 and the end wall 14 is limited in the mounting hole, and the outer edge 722 surrounding the outer edge of the electrode terminal 40 further limits the second fixing part 42. This facilitates assembly while ensuring that the second fixing part 42 can press down on the second insulating member 72, minimizing the offset between the two. The force on the second insulating member 72 is more even, avoiding excessive force in some areas that could damage the second insulating member 72. This improves the sealing performance of the secondary battery 100 at the second insulating member 72 and prevents the second fixing part 42 from crossing the second insulating member 42 and contacting the end wall 14, ensuring that the second insulating member 72 provides insulation between the electrode terminal 40 and the end wall 14.

[0096] Reference Figure 7 and Figure 10 The first insulating member 71 includes a second groove 718, which is located on the side of the first insulating member 71 facing the end wall 14 or the first fixing part 41, and is exposed on the side of the first insulating member 71 facing the seal 90. The first groove 728 and / or the second groove 718 are used for helium gas detection to check whether the seal 90 is missing. When the seal 90 is missing, the second groove 718 connects with the mounting hole and the first groove 718 to form a connecting channel. During helium detection, gas flows from the second groove 718, the mounting hole, and the first groove 718 to the outside of the secondary battery 100, further increasing the reliability of the sealing detection.

[0097] The secondary battery 100 in this embodiment is, for example, a cylindrical battery. The casing 10 is made of nickel-coated steel, and the surface of the nickel-coated steel has a nickel coating. The nickel coating is mainly used to prevent the electrolyte from corroding the nickel-coated steel. Using nickel-coated steel as the casing of a cylindrical battery requires higher sealing performance. If the sealing performance is poor, water will enter the cylindrical battery and react with the electrolyte to produce hydrogen ions. The hydrogen ions will react with the nickel coating of the nickel-coated steel, corroding the casing 10 and generating nickel ions. The nickel ions will integrate into / enter the electrode assembly 120, generating nickel metal, which may cause a short circuit between the positive electrode 121 and the negative electrode 123 of the electrode assembly 120, affecting the safety of the cylindrical battery. The embodiments of this application improve the sealing reliability of the secondary battery 100 at the second insulating member 72 by ensuring the structural strength of the second insulating member 72, and further improve the sealing performance of the interface between the insulating member 70 and the electrode terminal 40 and the end wall 14, so as to prevent water molecules from seeping into the housing 10 from the electrode terminal 40, avoid the above-mentioned technical problems, and improve the safety of the secondary battery 100.

[0098] 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: A housing having an opening at one axial end and an end wall at the opposite end, the end wall having a mounting hole; Electrode assembly, disposed within the housing; An electrode terminal is fixed to the end wall and electrically connected to the electrode assembly. The electrode terminal includes a through portion passing through the mounting hole, a first fixing portion disposed on the inner side of the end wall in the axial direction, and a second fixing portion disposed on the outer side of the end wall in the axial direction (42). A seal surrounds the through portion and is at least partially pressed between the first fixing portion and the end wall; A first insulating element surrounds the seal and is at least partially clamped between the first fixing portion and the end wall; A second insulating member is riveted around the through portion, the second fixing portion, and the end wall, and at least a portion of the second insulating member is pressed between the second fixing portion and the end wall. The second insulating member includes an inlet and a weld line spaced apart from the inlet in the circumferential direction of the second insulating member. The second insulating member also includes a first groove that avoids the inlet and the weld line in the circumferential direction.

2. The secondary battery according to claim 1, characterized in that, The glue inlet and the first groove are located on the same surface of the second insulating member, perpendicular to the axial direction.

3. The secondary battery according to claim 2, characterized in that, The number of the first grooves is n, n≥2, and the n first grooves are equidistantly distributed along the circumference of the second insulating component.

4. The secondary battery according to claim 2 or 3, characterized in that, The same surface faces the outer side of the end wall, and the insulating component also includes a glue inlet, which is disposed inside the glue inlet.

5. The secondary battery according to claim 4, characterized in that, The depth of the injection port is H mm, and the depth of the first groove is h mm, where 0.7 ≤ H / h ≤ 1.

3.

6. The secondary battery according to claim 1, characterized in that, The second insulating member further includes an outer edge portion surrounding the outer periphery of the second fixing portion and an inner edge portion located between the through portion and the end wall.

7. The secondary battery according to claim 1, characterized in that, The first insulating member includes a second groove located on the side of the first insulating member facing the end wall or the first fixing portion, and the second groove is exposed on the side of the first insulating member facing the seal.

8. The secondary battery according to claim 7, characterized in that, The first groove and / or the second groove are used for helium gas detection to check whether the seal is missing.

9. A battery pack, characterized in that, Includes a secondary battery as described in any one of claims 1 to 8, and a busbar, wherein the busbar is connected in series or in parallel to the electrode terminals of the secondary battery, and the second insulating member is made of soluble polytetrafluoroethylene.

10. An electrical appliance, characterized in that, Includes the battery pack as described in claim 9.

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