Secondary batteries and battery packs

Abstract

This utility model provides a secondary battery and battery pack. The secondary battery includes: a casing, including an end wall and a side wall surrounding the end wall, the end wall having an electrode post hole; an electrode post passing through the electrode post hole and including an inner flange disposed on the side of the end wall facing the interior of the casing; and a lower plastic assembly disposed between the end wall and the inner flange; wherein the inner flange is riveted to the lower plastic assembly, the lower plastic assembly has a protrusion surrounding the electrode post on the side facing the inner flange, the inner flange is pressed against the protrusion, and the radially inclined end of the inner flange is pressed against the lower plastic assembly, the pressing position of the end of the inner flange and the lower plastic assembly being located radially outside the protrusion. This technical solution can at least improve the battery's sealing performance.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and more specifically, to a secondary battery and battery pack. Background Technology

[0002] In the field of new energy power batteries, secondary batteries generally include electrode components, housings, and cover plates. Electrode components include positive electrode plates, negative electrode plates, and a separator located between the positive and negative electrode plates. These positive electrode plates, negative electrode plates, and separators are stacked together to form electrode components directly or wound together, and then encapsulated in the housing.

[0003] Typically, the lower plastic seal is located between the electrode assembly and the end wall of the housing. The internal electrode post and the lower plastic seal are riveted together to prevent the electrode assembly from shifting and to provide insulation. However, the sealing performance of the lower plastic seal still needs further improvement. Utility Model Content

[0004] 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 sealing performance of the lower plastic.

[0005] To achieve the above objectives, this utility model provides a secondary battery, which includes: a housing, including an end wall and a side wall surrounding the end wall, the end wall having an electrode post hole; an electrode post passing through the electrode post hole and including an inner flange disposed on the side of the end wall facing the interior of the housing; and a lower plastic disposed between the end wall and the inner flange; wherein, the inner flange is riveted to the lower plastic, the lower plastic having a protrusion surrounding the electrode post on the side facing the inner flange, the inner flange being pressed against the protrusion, and the radial end of the inner flange being pressed against the lower plastic, the pressing position of the end of the inner flange and the lower plastic being located radially outside the protrusion.

[0006] In some embodiments, the protrusion includes a first sidewall and a second sidewall that are radially opposed, and a top wall that contacts the inner flange, wherein the first sidewall and the second sidewall gradually approach each other in the direction from the end wall toward the inner flange.

[0007] In some embodiments, the first sidewall is closer to the pole hole in the radial direction than the second sidewall, and the first sidewall and the top wall are connected by a rounded transition, the radius of which ranges from 0.05 mm to 0.4 mm.

[0008] In some embodiments, the radial distance between the outer edge of the end portion and the radial distance between the protrusion and the end portion is a, where a ≥ 0.1 mm.

[0009] In some embodiments, the pole post further includes a column portion that passes through the pole post hole and is connected to an inner flange. The inner flange has a rounded corner connected to the column portion on the side facing the end wall. The radial distance between the rounded corner and the protrusion is b, where b ≥ 0.1 mm.

[0010] In some embodiments, the end portion includes a first surface facing down plastic, a second surface facing away from down plastic, and a side surface. The side surface is connected between the first surface and the second surface. The included angle between the first surface and the side surface is N°, wherein 60° < N° ≤ 90°. The end portion is pressed into the lower plastic to form a receiving groove in the lower plastic to receive the end portion.

[0011] In some embodiments, the pole post further includes a column portion that passes through the pole post hole and is connected to an inner flange. The inner flange has a rounded corner connected to the column portion on the side facing the end wall. The distance between the end of the rounded corner near the end and the outer edge of the end in the radial direction is L. The width of the protrusion in the radial direction is T3, and the value of T3 / L ranges from 13% to 40%.

[0012] In some embodiments, the compression ratio of the protrusion ranges from 50% to 80%, and the lower plastic is made of soluble polytetrafluoroethylene plastic.

[0013] In some embodiments, the thickness of the pressed protrusion is T1, and the value of T1 ranges from 0.05 mm to 0.2 mm.

[0014] This utility model also provides a battery pack, which includes the aforementioned secondary battery.

[0015] The beneficial technical effects of this utility model include:

[0016] By providing a protrusion on the lower plastic being pressed against the inner flange, the riveting force and extrusion force of the inner flange on the lower plastic can be increased. The protrusion can reduce or eliminate the gap between the inner flange and the lower plastic, thereby improving the battery's sealing performance. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic cross-sectional view of an existing secondary battery on one side of the terminal post is shown.

[0019] Figure 2 A front view of a secondary battery according to an embodiment of this application is shown.

[0020] Figure 3 It shows along Figure 2 A cross-sectional view taken from line C1-C1.

[0021] Figure 4 It shows Figure 3 A magnified view of the region Ap in the image.

[0022] Figure 5 An enlarged view of the protrusion according to an embodiment of this application is shown.

[0023] Figure 6 A comparison graph showing the weight loss of DMC at 60℃ is shown.

[0024] Figure 7 A schematic diagram of an electronic device according to an embodiment of this application is shown. Detailed Implementation

[0025] To better understand the spirit of the embodiments of this application, the following description is based on some preferred embodiments of this application.

[0026] 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.

[0027] As used herein, the terms “approximately,” “generally,” “substantially,” and “about” are used to describe and indicate minor variations. When used in conjunction with an event or situation, these terms may refer to examples in which the event or situation occurred precisely or in examples in which the event or situation occurred very approximately.

[0028] 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.

[0029] 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.

[0030] With the rapid development of new energy vehicles, small cylindrical batteries can no longer meet the demand, necessitating the development of large cylindrical batteries to pursue higher energy performance. During high-temperature storage of large cylindrical cells, the casing corrodes and turns black, and the resulting decrease in OCV (Open Circuit Voltage) has become an industry challenge.

[0031] The seal of the housing is key to improving OCV descent. See also Figure 1 As shown, the lower plastic 21 is a component that assists in sealing the housing, and its tight fit with the housing interface is an important factor in improving the sealing performance. However, the current lower plastic 21 has a planar structure. When the riveted inner flange 11 of the electrode post 10 compresses the lower plastic 21, it forms an inner corner 32, resulting in a groove 11r near the inner corner 32, which weakens the sealing performance of the lower plastic 21. Embodiments of this application provide a secondary battery to at least solve the above-mentioned technical problems.

[0032] Figure 2 A front view of a secondary battery 100 according to an embodiment of this application is shown. Figure 3 It shows along Figure 2 A cross-sectional view taken along line C1-C1. See [reference needed]. Figure 2 and Figure 3 As shown, the secondary battery 100 may include a housing assembly, which includes a housing 200 and a cover plate 220. The housing 200 may include an end wall 110 and a side wall 112 surrounding the end wall 110. The side wall 112 is connected to the outer edge of the end wall 110. The end wall 110 and the side wall 112 may define a receiving cavity to receive the electrode assembly of the secondary battery 100. The side wall 112 may have an opening at one end opposite to the end wall 110, and the cover plate 220 closes to the opening to seal the electrode assembly within the receiving cavity.

[0033] As long as a stable seal and electrical connection can be formed, the connection between the end wall 110 and the side wall 112 can be achieved in various ways, such as integral stamping, integral casting, or separate welding. The circumference of the side wall 112 is not limited; it can be cylindrical or prismatic, or follow any other closed-loop contour that matches the end wall. A receiving cavity is formed within the housing 200, which, in addition to the electrode assembly, can also accommodate the electrolyte, current collector, and other necessary battery components. The diameter of the housing 200 can be determined based on the specific dimensions of the electrode assembly. The housing 200 can be made of various materials, such as copper, iron, aluminum, steel, or aluminum alloy. To prevent rusting during long-term use, a rust-preventive material such as nickel can be plated onto the surface of the housing 200. The secondary battery 100 can be a cylindrical battery, such as a 4680 cylindrical battery with a height of 80mm and an outer diameter of 46mm; or, for example, a battery with a height of 150mm and an outer diameter of 46mm.

[0034] The secondary battery 100 may further include a lower plastic 130 and a terminal post 150. The lower plastic 130 is disposed on the inner surface 110a of the end wall 110 facing the interior of the housing 200, and the lower plastic 130 has a through hole for the terminal post 150 to pass through, that is, the lower plastic 130 can be disposed around the terminal post 150. The end wall 110 has a terminal post hole 118, through which the terminal post 150 passes. In addition, a portion of the lower plastic 130 may be disposed within the terminal post hole 118 and located radially between the terminal post 150 and the end wall 110 of the housing 200. The radial direction of the housing 200 is parallel to the X direction. The terminal post 150 includes an inner flange 152, which is disposed on one side of the inner surface 110a of the end wall 110. The lower plastic 130 is disposed between the end wall 110 and the inner flange 152, and the inner flange 152 is riveted to the lower plastic 130. The inner flange 152 can also be referred to as a riveted flange. The lower plastic 130 can be used to electrically insulate the retaining post 150 from the end wall 110.

[0035] More specifically, the pole post 150 may further include an outer flange 153 and a cylindrical portion 151. The outer flange 153 is located outside the housing 200, and the cylindrical portion 151 passes through the pole post hole 118. The cylindrical portion 151 may be the portion of the pole post 150 located within the pole post hole 118 along the axial direction of the pole post hole 118. The axial direction of the pole post hole 118 is parallel to the Z direction. The cylindrical portion 151 may be cylindrical. The outer flange 153 is connected to the end of the cylindrical portion 151 facing the outside of the housing 200, and the inner flange 152 is connected to the end of the cylindrical portion 151 facing the inside of the housing 200. The inner flange 152 and the outer flange 153 may each extend radially beyond the pole post hole 118 of the housing. When riveting the electrode post, the electrode post 150 passes through the electrode post hole 118 and the through hole of the lower plastic 130 in sequence. The inner flange 152 is bent towards the lower plastic 130 relative to the column body 151 so that the electrode post 180 is fixed to the end wall 110. Specifically, before riveting, the inner flange 152 extends along the axial direction of the column body 151. When riveting the electrode post, the inner flange 152 is bent towards the lower plastic 130 relative to the column body 151. The side of the inner flange 152 facing the end wall 110 has a rounded corner 152r that connects to the column body 151.

[0036] The secondary battery 100 may further include a sealing ring 170, which is located between the outer surface 110b of the end wall 110 facing the outside of the housing and the outer flange 153 of the terminal post 150, and is circumferentially disposed around the post portion 151 to form a circumferential seal. The sealing ring 170 may also surround a portion of the side surface of the outer flange 153. In some embodiments, the sealing ring 170 may be made of FKM (fluororubber-based elastomer) material.

[0037] Figure 4 It shows Figure 3 A magnified view of region Ap in the image. (Reference) Figure 3 and Figure 4 As shown, the lower plastic 130 has a protrusion 135 on the side facing the inner flange 152. The protrusion 135 can surround the terminal post 150. The inner flange 152 is pressed against the protrusion 135. The radial end 154 of the inner flange 152 is pressed against the lower plastic 130. The pressing position of the end 154 against the lower plastic 130 is located radially outside the protrusion 135. That is, the protrusion 135 is provided in the area of ​​the lower plastic 130 pressed against by the inner flange 152. By providing the protrusion 135 on the pressed lower plastic 130 facing the inner flange 152, the riveting force and extrusion force of the inner flange 152 on the lower plastic 130 can be increased. The protrusion 135 can reduce or eliminate the gap between the inner flange 152 and the lower plastic 130, improving the battery sealing performance. Furthermore, the problem of OCV decline can be improved.

[0038] Figure 5 An enlarged view of the protrusion 135 is shown. (Combined) Figures 3 to 5As shown, the protrusion 135 may specifically include a first sidewall 135a and a second sidewall 135b that are radially opposite each other, and a top wall 135c that contacts the inner flange 152. The first sidewall 135a is closer to the pole hole 118 in the radial direction than the second sidewall 135b. The first sidewall 135a and the second sidewall 135b extend obliquely, respectively. And along the direction Z, the first sidewall 135a and the second sidewall 135b gradually approach each other. In this way, the first sidewall 135a, the second sidewall 135b and the top wall 135c form a trapezoidal or similar trapezoidal structure for the protrusion 135. By setting the protrusion 135 in such a structure, the protrusion 135 can be prevented from affecting the folding of the inner flange 152 when riveting the pole.

[0039] The first sidewall 135a and the top wall 135c can be connected by a fillet 135m. Since the first sidewall 135a is closer to the bending angle between the inner flange 152 and the column portion 151, the fillet 135m at the transition between the first sidewall 135a and the top wall 135c can avoid affecting the folding of the inner flange 152 and facilitate the bending of the inner flange 152.

[0040] In some embodiments, the radius of the fillet 135m can range from 0.05mm to 0.4mm. If the radius of the fillet 135m reaches 0.05mm, the influence of the protrusion 135 on the bending and riveting of the inner flange 152 can be avoided; if the radius of the fillet 135m exceeds 0.4mm, it may lead to a reduction in the top wall 135c, which can form a better seal.

[0041] In some embodiments, the first sidewall 135a and the top wall 135c can be connected by a fillet 135n. The radius of the fillet 135n can range from 0.05mm to 0.4mm. A fillet 135u can also be provided at the opposite end of the first sidewall 135a and the fillet 135n. A fillet 135v can also be provided at the opposite end of the second sidewall 135b and the fillet 135n.

[0042] The end portion 154 of the inner flange 152 may include a first surface 154a pressed against and in contact with the lower plastic 130, a side surface 154b connected to the first surface 154a, and a second surface 154c facing away from the lower plastic 130, the side surface 154b connecting the first surface 154a and the second surface 154c. An angle 158 is formed between the first surface 154a and the side surface 154b of the end portion 154, the included angle being N°. In some embodiments, 60° < N° ≤ 90°. An included angle 158 less than or equal to 90° facilitates the inner flange 152 being pressed into the lower plastic 130. An included angle 158 greater than 60° prevents the end portion 154 from being too sharp and cracking the lower plastic 130. In some embodiments, the end portion 154 is pressed against the lower plastic 130, causing the lower plastic 130 to form a receiving groove for accommodating the end portion 154.

[0043] The radial distance between the outer edge of the end portion 154 and the radial distance between the protrusion 135 and the end portion 154 is a. In some embodiments, a ≥ 0.1 mm, to ensure that the distance between the protrusion 135 and the outer edge of the end portion 154 is not less than 0.1 mm, to avoid the protrusion 135 having an adverse effect on the folding and pressing of the end portion 154, and to ensure that the end portion 154 can be effectively riveted to the lower plastic 130.

[0044] The radial distance between the fillet 152r and the protrusion 135 is b. Specifically, b is the distance between the ends of the fillet 152r and the fillet 135u that are close to each other. In some embodiments, b ≥ 0.1 mm to ensure that the distance between the protrusion 135 and the fillet 152r at the bending position of the inner flange 152 is not less than 0.1 mm, so as to avoid the protrusion 135 having an adverse effect on the folding and pressing of the inner flange 152.

[0045] The distance L between the end of the fillet 152r near the end 154 and the outer edge of the end 154 in the radial direction is 152r. The radial width of the protrusion 135 is T3. In some embodiments, the width T3 of the protrusion 135 ranges from 0.2 mm to 0.6 mm. In some embodiments, the value of T3 / L ranges from 13% to 40%. When T3 / L is less than 30%, the protrusion 135 does not fill the gap between the inner flange 152 and the lower plastic 130 sufficiently, resulting in poor sealing. When T3 / L is greater than 40%, the end 154 is difficult to press against the lower plastic 130 during the riveting and folding process due to the influence of the protrusion 135, and an effective riveting cannot be formed.

[0046] The inner flange 152 presses against the protrusion 135, thereby compressing the protrusion 135. In some embodiments, the compression rate of the protrusion 135 is in the range of 50% to 80%. A compression rate of less than 80% can prevent the protrusion 135 from cracking. By providing a large riveting force through the inner flange 152 to rivet the lower plastic, a compression rate of more than 50% for the protrusion 135 can effectively improve the sealing performance. In this application, the compression rate = 1 - T1 / T2, the thickness of the pressed protrusion 135 is T1, that is, T1 is the thickness of the protrusion 135 after compression, and T2 is the thickness of the protrusion 135 before compression. In some embodiments, the value of T1 ranges from 0.05 mm to 0.2 mm.

[0047] In some embodiments, the lower plastic 130 may be made of PFA (soluble polytetrafluoroethylene), which reduces the likelihood of the lower plastic 130 being crushed. It should be understood that the material of the lower plastic 130 is not limited to PFA, and other suitable materials may also be used.

[0048] The beneficial effects of the technical solution of this application can be verified by DMC (dimethyl carbonate) weight loss verification (DMC is one of the main solvents of lithium-ion battery electrolyte), that is, the effect of the setting of the protrusion 135 on the sealing performance of the secondary battery 100. Figure 6 A comparison graph showing the weight loss of DMC at 60°C is presented. Figure 6 In the diagram, curve S1 represents the DMC weight loss fitting curve of the secondary battery 100 without the protrusion 135, and S1 is obtained by fitting multiple measurement points P1 of the DMC weight loss at different storage days. Curve S2 represents the DMC weight loss fitting curve of the secondary battery 100 with the protrusion 135 provided in this application, and S2 is obtained by fitting multiple measurement points P2 of the DMC weight loss at different storage days.

[0049] Depend on Figure 6 The verification results shown indicate that, with increasing storage days, the lower plastic with protrusion 135 results in less battery weight loss. This suggests that the lower plastic with protrusion 135 provides better sealing.

[0050] See Figure 7This application also provides an electronic device 1000 and its battery pack 1002, the battery pack 1002 including any of the aforementioned secondary batteries. For ease of explanation, the following embodiments use a vehicle as an example to illustrate the electronic device 1000. The battery pack 1002 is installed inside the vehicle and can be located at the bottom, front, or rear of the vehicle body. The battery pack 1002 can be used to power the vehicle; for example, it can serve as the vehicle's operating power source. The working part of the electronic device 1000 is electrically connected to the battery pack 1002 to obtain electrical power support. The vehicle 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 working part is the vehicle body, and the battery pack 1002 is located at the bottom of the vehicle body, providing electrical power support for the vehicle's operation or the operation of electrical components within the vehicle. However, in some other embodiments, the electronic device 1000 can also be a mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, power tool, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; the working unit can obtain electrical energy from the battery pack 1002 and perform 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. The embodiments of this application do not impose special limitations on the above-mentioned electronic device 1000.

[0051] 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 includes an end wall and a side wall surrounding the end wall, the end wall being provided with pole post holes; The electrode post passes through the electrode post hole and includes an inner flange disposed on the side of the end wall facing the interior of the housing; as well as The lower plastic is disposed between the end wall and the inner flange; The inner flange is riveted to the lower plastic, and the lower plastic has a protrusion surrounding the pole on the side facing the inner flange. The inner flange is pressed against the protrusion, and the end of the inner flange in the radial direction of the housing is pressed against the lower plastic. The pressing position of the end of the inner flange and the lower plastic is located on the outside of the protrusion in the radial direction.

2. The secondary battery according to claim 1, characterized in that, The protrusion includes a first sidewall and a second sidewall that are radially opposite each other, and a top wall that contacts the inner flange, wherein the first sidewall and the second sidewall gradually approach each other in the direction from the end wall toward the inner flange.

3. The secondary battery according to claim 2, characterized in that, The first sidewall is closer to the pole hole in the radial direction than the second sidewall, and the first sidewall and the top wall are connected by a rounded transition, the radius of which ranges from 0.05 mm to 0.4 mm.

4. The secondary battery according to claim 1, characterized in that, The distance between the outer edge of the end portion in the radial direction and the convex portion in the radial direction is a, where a ≥ 0.1 mm.

5. The secondary battery according to claim 1, characterized in that, The pole post also includes a column portion, which passes through the pole post hole and is connected to the inner flange. The inner flange has a rounded corner on the side facing the end wall that is connected to the column portion. The distance between the rounded corner and the protrusion in the radial direction is b, where b ≥ 0.1 mm.

6. The secondary battery according to claim 1, characterized in that, The end portion includes a first surface facing the lower plastic, a second surface facing away from the lower plastic, and a side surface. The side surface is connected between the first surface and the second surface. The included angle between the first surface and the side surface is N°, wherein 60° < N° ≤ 90°. The end portion is pressed against the lower plastic to form a receiving groove in the lower plastic to accommodate the end portion.

7. The secondary battery according to claim 1, characterized in that, The pole post also includes a column portion, which passes through the pole post hole and is connected to the inner flange. The inner flange has a rounded corner on the side facing the end wall that connects to the column portion. Wherein, the distance between the end of the fillet near the end and the outer edge of the end in the radial direction is L, the width of the protrusion in the radial direction is T3, and the value of T3 / L ranges from 13% to 40%.

8. The secondary battery according to claim 7, characterized in that, The compression ratio of the protrusion ranges from 50% to 80%, and the lower plastic is made of soluble polytetrafluoroethylene plastic.

9. The secondary battery according to any one of claims 1-8, characterized in that, The thickness of the protrusion being pressed is T1, and the value of T1 ranges from 0.05 mm to 0.2 mm.

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

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