Cylindrical secondary battery, battery pack, and electric device

Abstract

A cylindrical secondary battery, a battery pack (200), and an electric device (300), the cylindrical secondary battery including a case (10), an electrode assembly (20), a first electrode terminal (30), and a current cutoff device (40) electrically connecting the electrode assembly (20) and the first electrode terminal (30), the first electrode terminal (30) being a negative electrode of the cylindrical secondary battery.

Description

Technical Field

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

[0002] Secondary batteries, such as lithium-ion batteries, have high energy density and long service life, and are therefore widely used.

[0003] The casing of cylindrical lithium-ion batteries is typically made of steel to accommodate various operating conditions. A current interruption device (CID) is usually installed inside the casing. The CID is electrically connected to the positive electrode of the lithium-ion battery, while the casing acts as the negative electrode. When the internal pressure of the lithium-ion battery casing becomes too high, the CID can disconnect the charging and discharging circuit, providing safety protection for the battery.

[0004] As the demand for battery capacity increases, the size of the casing also increases. When a longer casing is required, it is difficult to process steel casings to the required length due to the low ductility of steel. Summary of the Invention

[0005] The purpose of this application is to provide a cylindrical secondary battery, a battery pack, and an electrical device to facilitate the fabrication of long-sized secondary batteries.

[0006] The first aspect of this application provides a cylindrical secondary battery, comprising: a casing; an electrode assembly disposed within the casing; a first electrode terminal insulated from and connected to the casing; and a current-cutting device electrically connected to the electrode assembly and the first electrode terminal, wherein the first electrode terminal is the negative electrode of the cylindrical secondary battery. The current-cutting device facilitates improved safety of the secondary battery. Since the casing of the cylindrical secondary battery is not exposed to the low potential environment of the negative electrode, it facilitates the selection of casing materials, enabling the fabrication of long-sized secondary batteries.

[0007] In one or more embodiments, the casing serves as the positive electrode of the cylindrical secondary battery, thereby saving the need for electrode terminals that would otherwise be used as the positive electrode.

[0008] In one or more embodiments, the casing material comprises aluminum or an aluminum alloy; and / or, the first electrode terminal material comprises aluminum or an aluminum alloy. The casing material, comprising aluminum or an aluminum alloy, has good ductility, which facilitates stretching the sidewalls to a longer dimension, making it easier to fabricate large-volume, high-capacity cylindrical secondary batteries. The first electrode terminal material, comprising aluminum or an aluminum alloy, facilitates the welding of the positive or negative electrode of the cylindrical secondary battery to the aluminum busbar.

[0009] In one or more embodiments, the housing includes a top wall, a first electrode terminal, and an insulated connection between the top wall and the first electrode terminal; both the top wall and the first electrode terminal are made of aluminum-manganese alloy. When the top wall is the positive electrode of a cylindrical secondary battery, since both the positive and negative electrodes of the cylindrical secondary battery are made of aluminum-manganese alloy, it facilitates the welding of the positive or negative electrode of the cylindrical secondary battery to the aluminum busbar.

[0010] In one or more embodiments, the casing includes sidewalls made of an aluminum-manganese alloy. Using an aluminum-manganese alloy for the sidewalls facilitates stretching them into longer dimensions, making it easier to fabricate large-volume, high-capacity cylindrical secondary batteries.

[0011] In one or more embodiments, the current interruption device includes an explosion-proof plate and a connecting plate electrically connected to each other. The explosion-proof plate is electrically connected to a first electrode terminal, and the connecting plate is electrically connected to an electrode assembly. After the gas pressure inside the cylindrical secondary battery casing rises to a first threshold, the explosion-proof plate and the connecting plate disconnect from the electrical connection, thereby disconnecting the current loop between the positive and negative terminals of the cylindrical secondary battery and improving the safety of the secondary battery.

[0012] In one or more embodiments, the connecting plate is made of steel, nickel, copper, nickel-plated copper, or a copper-nickel alloy; the explosion-proof sheet is made of steel, nickel, copper, nickel-plated copper, or a copper-nickel alloy. The connecting plate and explosion-proof sheet are located in a low-potential environment at the negative electrode. The materials selected for these components, including steel, nickel, copper, nickel-plated copper, or a copper-nickel alloy, are less likely to chemically react with lithium ions and corrode in this low-potential environment, thus making them suitable for cylindrical lithium-ion secondary batteries.

[0013] In one or more embodiments, both the explosion-proof plate and the connecting plate are made of copper; or, both the explosion-proof plate and the connecting plate are made of nickel-plated copper. Copper has low electrical resistance, which helps to reduce the resistance of the cylindrical secondary battery and reduce its heat generation. Nickel-plated copper has good rust resistance, which facilitates the improvement of the weldability and rust resistance of the explosion-proof plate of the cylindrical secondary battery. Using the same material for the explosion-proof plate and the connecting plate facilitates welding.

[0014] In one or more embodiments, the connecting plate includes a first part and a second part connected to each other, the first part surrounding the second part, the first part being connected to the electrode assembly, and the second part being connected to the explosion-proof sheet; the thickness of the first part is H1, the thickness of the second part is H2, and 0.3≤H2 / H1≤0.8. Because the thickness of the second part of the connecting plate is less than the thickness of the first part, when the explosion-proof sheet is flipped, the second part is easily separated from the first part by the flipping action of the explosion-proof sheet, thereby disconnecting the electrical connection between the connecting plate and the explosion-proof sheet.

[0015] In one or more embodiments, 0.1mm≤H1≤0.5mm, using the above-mentioned thickness range of H1, the resistance of the connecting plate is small and meets the current transfer capability of the cylindrical secondary battery.

[0016] In one or more embodiments, the explosion-proof sheet includes a third part and a fourth part connected to each other. Along the axial direction of the cylindrical secondary battery, the projection of the fourth part surrounds the projection of the third part. The third part and the second part are connected, and the fourth part is connected to the first electrode terminal. The thickness of the third part is H3, where 1.3 ≤ H3 / H2 ≤ 3. Because the thickness of the third part of the explosion-proof sheet is greater than the thickness of the second part of the connecting plate, the third part has good strength, which is beneficial for the explosion-proof sheet to separate the second part and the first part when flipped, thereby disconnecting the electrical connection between the connecting plate and the explosion-proof sheet.

[0017] In one or more embodiments, the connecting plate is welded to the explosion-proof sheet, and the welding area is S, 0.8 mm. 2 ≤S≤4mm 2 The welding area S, while ensuring a good electrical connection between the connecting plate and the explosion-proof sheet, facilitates a relatively quick disconnection of the electrical connection between the explosion-proof sheet and the connecting plate when the gas pressure inside the casing reaches the first threshold.

[0018] In one or more embodiments, the cylindrical secondary battery includes a first insulating member, at least a portion of which is disposed between a first part and a fourth part; the thickness of the first insulating member disposed between the first part and the fourth part is H4, and 1.5 ≤ H4 / H2 ≤ 5. After the explosion-proof sheet is flipped, if the second part produces residue that separates freely during the breakage process with the first part, since the thickness of the first insulating member is greater than the thickness of the second part, the residue will fall between the first part and the fourth part and is unlikely to make simultaneous electrical connection with both the first part and the fourth part, thus short-circuiting the explosion-proof sheet and the connecting plate; if the value of H4 / H2 is too large, it will easily lead to an increase in the length of the cylindrical secondary battery, resulting in a loss of energy density.

[0019] In one or more embodiments, 0.3mm≤H4≤0.7mm, and the range of H4 values ​​is beneficial for maintaining good insulation performance between the first part and the fourth part with a reasonable thickness.

[0020] In one or more embodiments, the first insulating element is made of ceramic. Ceramic has a high melting point and is not easily melted, which is beneficial for maintaining good insulation between the first and fourth parts in the high-temperature environment inside a large-capacity cylindrical secondary battery, reducing the risk of CID failure.

[0021] In one or more embodiments, the ceramic includes oxide ceramics or non-oxide ceramics; oxide ceramics include at least one of Al2O3, ZrO, MgO, CaO, B2O3, ThO2, Cr2O3, SiO2, BeO, and 3Al2O3·2SiO2; non-oxide ceramics include at least one of carbide ceramics, boride ceramics, nitride ceramics, or silicide ceramics. The above materials have high melting points and are not easily melted, which is beneficial for maintaining good insulation performance between the first and fourth parts in the high-temperature environment inside a large-capacity cylindrical secondary battery, reducing the risk of CID failure.

[0022] In one or more embodiments, the melting point of the first insulating element is t, where t ≥ 300°C. The high melting point of the first insulating element makes it less likely to melt in the cylindrical secondary battery under high-temperature conditions, which helps maintain good insulation between the first and fourth parts and reduces the risk of CID failure.

[0023] In one or more embodiments, t ≥ 500°C. The first insulating element has a higher melting point, making it less likely to melt in the cylindrical secondary battery under high-temperature conditions. This helps the first insulating element maintain good insulation between the first and fourth parts, reducing the risk of CID failure.

[0024] In one or more embodiments, t ≥ 800°C. The first insulating element has a higher melting point, making it less likely to melt in a cylindrical secondary battery under high-temperature conditions. This helps the first insulating element maintain good insulation between the first and fourth parts, reducing the risk of CID failure.

[0025] In one or more embodiments, it further includes: a support member; the housing includes a top wall, and the first electrode terminal and the top wall are insulatedly connected; the support member is disposed between the electrode assembly and the top wall, and the support member supports the electrode assembly, which helps to suppress the movement of the electrode assembly and improve the service life of the cylindrical secondary battery.

[0026] In one or more embodiments, the device further includes: a current collector plate electrically connected to the electrode assembly, a portion of which is disposed between the electrode assembly and the support member; the support member includes a through hole, a portion of which is disposed in the through hole and electrically connected to the current collector plate. The support member provides support for the current collector plate, which helps improve the positional stability of the current collector plate. The portion of the current cut-off device being disposed in the through hole of the support member helps the support member to radially limit the current cut-off device within the cylindrical secondary battery.

[0027] In one or more embodiments, the current cut-off device is configured to disconnect when the gas pressure inside the housing reaches a first threshold, thereby disconnecting the electrode assembly and the first electrode terminal from the electrical connection, so as to disconnect the current loop between the positive and negative terminals of the cylindrical secondary battery and improve the safety of the secondary battery.

[0028] In one or more embodiments, the cylindrical secondary battery is a round secondary battery with a diameter D of 25mm ≤ D ≤ 65mm; and / or, the length L of the round secondary battery is 80mm ≤ L ≤ 250mm. The cylindrical secondary battery of this embodiment has a relatively long size and a large capacity, making it suitable for use in high-power or large battery packs and electrical devices.

[0029] A second aspect of this application provides a battery pack including the cylindrical secondary battery of any of the above embodiments.

[0030] A third aspect of this application provides an electrical device including a cylindrical secondary battery or battery pack of any of the above embodiments.

[0031] The beneficial effects of this application are:

[0032] This application provides a cylindrical secondary battery, a battery pack, and an electrical device. The cylindrical secondary battery includes a casing, an electrode assembly, a first electrode terminal, and a current cutting-off device. The current cutting-off device is electrically connected to the electrode assembly and the first electrode terminal to improve the safety of the secondary battery. Furthermore, compared to existing technologies, in this embodiment, the first electrode terminal is the negative electrode of the cylindrical secondary battery, and the first electrode terminal is insulated from the casing. This prevents the casing from being in a low-potential environment like a negative electrode, making it less susceptible to corrosion of materials with higher ductility than steel (such as aluminum). This allows for the selection of materials with higher ductility for the casing, facilitating the fabrication of long-sized secondary batteries. Attached Figure Description

[0033] The accompanying drawings, which are provided to further illustrate this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application.

[0034] Figure 1 This is a schematic diagram of the structure of a cylindrical secondary battery according to one embodiment of this application;

[0035] Figure 2 This is a schematic diagram of the exploded structure of a cylindrical secondary battery according to one embodiment of this application;

[0036] Figure 3 This is a partially exploded cross-sectional view of a cylindrical secondary battery according to one embodiment of this application.

[0037] Figure 4 This is a partial cross-sectional view of a cylindrical secondary battery according to one embodiment of this application.

[0038] Figure 5 for Figure 4 Enlarged view of A in the middle;

[0039] Figure 6This is a schematic diagram of the connection plate of a cylindrical secondary battery according to one embodiment of this application;

[0040] Figure 7 This is a cross-sectional view of the connecting plate of a cylindrical secondary battery according to one embodiment of this application.

[0041] Figure 8 This is a schematic diagram of the explosion-proof sheet of a cylindrical secondary battery according to one embodiment of this application;

[0042] Figure 9 This is a cross-sectional view of the explosion-proof sheet of a cylindrical secondary battery according to one embodiment of this application.

[0043] Figure 10 This is a schematic diagram of the structure of the first insulating component of a cylindrical secondary battery according to one embodiment of this application;

[0044] Figure 11 This is a cross-sectional view of the first insulating component of a cylindrical secondary battery according to one embodiment of this application.

[0045] Figure 12 This is a schematic diagram of the support structure for a cylindrical secondary battery according to one embodiment of this application;

[0046] Figure 13 This is a cross-sectional structural schematic diagram of the support structure of a cylindrical secondary battery according to one embodiment of this application;

[0047] Figure 14 This is a schematic diagram of the current collector of a cylindrical secondary battery according to one embodiment of this application;

[0048] Figure 15 This is a schematic diagram of the battery pack structure provided in the embodiments of this application;

[0049] Figure 16 This is a schematic diagram of the structure of the first type of electrical device provided in the embodiments of this application;

[0050] Figure 17 This is a schematic diagram of the structure of the second type of electrical device provided in the embodiments of this application.

[0051] The attached figures are labeled as follows:

[0052] Housing 10, top wall 11, second limiting part 111, annular groove 1111, side wall 12, electrode assembly 20, first electrode terminal 30, current cutting device 40, explosion-proof sheet 41, third part 411, fourth part 412, second annular groove 4121, flipping body 413, connecting plate 42, first part 421, vent hole 4211, second part 422, first annular groove 4221, first insulating part 43, fifth part 431, sixth part 432, welding wire 44, support member 50, first surface 50a, second surface 50b, through hole 51, first limiting part 52, first protrusion 521, second protrusion 53, groove 54, second through hole 55, collector plate 60, base 61, stack 62;

[0053] 100 cylindrical secondary batteries, 200 battery packs, and 300 electrical devices;

[0054] Axial direction Y, radial direction X, axis L0. Detailed Implementation

[0055] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0056] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items.

[0057] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0058] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. Where there is no conflict, the various embodiments in this application can be combined with each other.

[0059] In related technologies, steel is typically used for casings because it is not easily corroded by lithium ions in a low-potential negative electrode environment. However, steel has low ductility, making it difficult to process into long cylindrical secondary batteries. If a more ductile material such as aluminum is used for the casing, the aluminum casing will be corroded by lithium ions inside the lithium-ion battery in a low-potential negative electrode environment. The cylindrical secondary battery provided in this invention has a first electrode terminal that is the negative electrode, and this first electrode terminal is insulated from the casing. The casing itself is not the negative electrode, thus avoiding a low-potential negative electrode environment. This facilitates the use of materials with higher ductility than steel (such as aluminum) and the fabrication of long cylindrical secondary batteries using a stretching process. Furthermore, the cylindrical secondary battery has a CID structure, resulting in higher safety.

[0060] This application does not impose any particular limitation on the shape of the cylindrical secondary battery, as long as the inventive purpose of this application is achieved. In one or more embodiments, the cylindrical secondary battery is at least one of a cylindrical secondary battery, an elliptical cylindrical secondary battery, and a polygonal secondary battery (including a secondary battery with a regular polygonal cross-section or a secondary battery with an irregular polygonal cross-section).

[0061] To better understand the present invention, the cylindrical secondary battery of the present invention will be described in detail below with reference to the embodiments of the present invention.

[0062] It should be noted that the dimensions of various components and cylindrical secondary batteries shown in the accompanying drawings in the embodiments of this application are merely illustrative and should not constitute any limitation on this application.

[0063] Figure 1 This is a schematic diagram of the structure of a cylindrical secondary battery according to one embodiment of this application, as shown below. Figure 1 As shown, in a first aspect, embodiments of this application provide a cylindrical secondary battery 100, the axis of which is L0. The radial direction of the cylindrical secondary battery 100 is X, which is the direction from the axis L0 to the outer side of the cylindrical secondary battery 100 in a plane perpendicular to the axis L0. The axial direction of the cylindrical secondary battery 100 is Y, which is parallel to the axis L0 of the cylindrical secondary battery 100. The length of the cylindrical secondary battery 100 is L, and the diameter of the cylindrical battery is D.

[0064] Figure 2 This is a schematic diagram of the exploded structure of a cylindrical secondary battery according to one embodiment of this application. Figure 3 This is a partially exploded cross-sectional view of a cylindrical secondary battery according to one embodiment of this application. Figure 4 This is a partial cross-sectional view of a cylindrical secondary battery according to one embodiment of this application, as shown below. Figure 2 , Figure 3 and Figure 4As shown, the cylindrical secondary battery 100 includes: a housing 10, an electrode assembly 20, a first electrode terminal 30, and a current cutting-off device 40. The electrode assembly 20 is disposed inside the housing 10; the first electrode terminal 30 is insulated from and connected to the housing 10; the current cutting-off device 40 is electrically connected to the electrode assembly 20 and the first electrode terminal 30.

[0065] The first electrode terminal 30 is the negative electrode of the cylindrical secondary battery 100.

[0066] In one or more embodiments, the current cut-off device 40 is configured to disconnect when the air pressure inside the housing 10 reaches a first threshold, thereby disconnecting the electrode assembly 20 and the first electrode terminal 30 from electrical connection.

[0067] In one or more embodiments, the first threshold is P1, where 1.0 MPa ≤ P1 ≤ 1.6 MPa. For example, P1 can be: 1.0 MPa, 1.02 MPa, 1.04 MPa, 1.06 MPa, 1.08 MPa, 1.1 MPa, 1.12 MPa, 1.14 MPa, 1.16 MPa, 1.18 MPa, 1.2 MPa, 1.22 MPa, 1.24 MPa, 1.26 MPa. The pressure range is P1, which can be 1.28MPa, 1.3MPa, 1.32MPa, 1.34MPa, 1.36MPa, 1.38MPa, 1.4MPa, 1.42MPa, 1.44MPa, 1.46MPa, 1.48MPa, 1.5MPa, 1.52MPa, 1.54MPa, 1.56MPa, 1.58MPa, or any two values ​​within this range. When the internal pressure of the cylindrical secondary battery 10 rises to within the range P1, the current cut-off device 40 cuts off the electrical connection between the electrode assembly 20 and the first electrode terminal 30, facilitating the formation of an external circuit and improving the safety of the cylindrical secondary battery 100.

[0068] The casing 10 is not the negative electrode of the cylindrical secondary battery 100. Since the casing 10 is not in a low-potential negative electrode environment, it is convenient to select a material with higher ductility than steel and to use a stretching process to prepare a long cylindrical secondary battery 100.

[0069] This application does not impose any particular limitation on the material of the casing 10. In one or more embodiments, the casing 10 is made of a material with high ductility. For example, in one or more embodiments, the material of the casing 10 includes aluminum or an aluminum alloy. That is, the material of the casing 10 can be pure aluminum or an aluminum alloy. In one or more embodiments, the aluminum alloy includes an aluminum-manganese alloy. Because pure aluminum, aluminum alloys, and aluminum-manganese alloys have good ductility, in the preparation of the casing 10, compared with the casing 10 made of steel, the casing 10 made of aluminum is easier to prepare to the required length by a stretching process, which is convenient for the preparation of long cylindrical secondary batteries 100.

[0070] In one or more embodiments, the diameter of the cylindrical secondary battery 100 is D, where 25mm ≤ D ≤ 65mm, but is not limited thereto. For example, D can be: 25mm, 27mm, 29mm, 31mm, 33mm, 35mm, 37mm, 39mm, 41mm, 43mm, 45mm, 47mm, 49mm, 51mm, 53mm, 55mm, 57mm, 59mm, 61mm, 63mm, 65mm, or a range of any two values ​​within this range. In one or more embodiments, the length of the cylindrical secondary battery 100 is L, where 80mm ≤ L ≤ 250mm, but is not limited thereto. For example, L can be 80mm, 90mm, 100mm, 110mm, 120mm, 130mm, 140mm, 150mm, 160mm, 170mm, 180mm, 190mm, 200mm, 210mm, 220mm, 230mm, 240mm, 250mm, or a range of any two values ​​within this range. In related technologies, the diameter of the cylindrical secondary battery 100 is typically small, such as 18650, 21700, or 46800 batteries. The cylindrical secondary battery 100 in this embodiment is relatively long to facilitate its application in high-power or large battery packs and electrical devices.

[0071] This application does not impose any particular limitation on the positive electrode arrangement of the cylindrical secondary battery 100. In one or more embodiments, the cylindrical secondary battery further includes a second electrode terminal (not shown), which is insulated from the housing 10 and electrically connected to the electrode assembly 20. The second electrode terminal is the positive electrode of the cylindrical secondary battery 100, while the housing 10 is neither the positive nor the negative electrode of the cylindrical secondary battery 100. The cylindrical secondary battery 100 has a first electrode terminal 30 and a second electrode terminal, which are located at both ends of the cylindrical secondary battery 100. Due to the distance between them, they are unlikely to come into contact and short-circuit.

[0072] In one or more embodiments, unlike the embodiments described above, the cylindrical secondary battery 100 does not have a second electrode terminal. The housing 10 is electrically connected to the electrode assembly 20, and the housing 10 is the positive electrode of the cylindrical secondary battery 100. That is, the housing 10 is electrically connected to the positive electrode of the electrode assembly 20, and the first electrode terminal 30 is electrically connected to the negative electrode of the electrode assembly 20, so that the housing 10 is the positive electrode of the cylindrical secondary battery 100, and the first electrode terminal 30 is the negative electrode of the cylindrical secondary battery 100. Since there is no need to provide a second electrode terminal, the components for the second electrode terminal are saved, the number of components is reduced, the cylindrical secondary battery is easier to process and assemble, and the overall battery is shorter, which is beneficial to improving the energy density of the cylindrical secondary battery 100.

[0073] This application does not impose any particular limitation on the material of the first electrode terminal 30. In one or more embodiments, the material of the first electrode terminal 30 includes aluminum. The aluminum first electrode terminal 30 and the aluminum housing 10 or the aluminum alloy housing 10 are used together. The housing 10 is the positive electrode of the cylindrical secondary battery, and the first electrode terminal 30 is the negative electrode of the cylindrical secondary battery, which facilitates the welding of the positive or negative electrode of the cylindrical secondary battery to the aluminum busbar.

[0074] In one or more embodiments, the material of the first electrode terminal 30 is not limited to aluminum, but may also include aluminum alloy. The first electrode terminal 30 of aluminum alloy and the housing 10 of aluminum material or aluminum alloy are used together, which is also beneficial for welding the positive or negative electrode of the cylindrical secondary battery and the aluminum busbar.

[0075] In one or more embodiments, the housing 10 includes a top wall 11, a side wall 12, and a bottom wall (not shown). The first electrode terminal 30 is insulated from the top wall 11. Both the top wall 11 and the first electrode terminal 30 are made of aluminum-manganese alloy. The top wall 11 is the positive electrode of the cylindrical secondary battery 100. In one or more embodiments, the bottom wall is electrically connected to the positive electrode of the electrode assembly 20, and the side wall 12 is electrically connected to the top wall 11 and the bottom wall. When the cylindrical secondary battery 100 is used in a battery pack, the positive and negative electrodes of multiple cylindrical secondary batteries 100 are electrically connected by corresponding aluminum busbars. Since the positive and negative electrodes of the cylindrical secondary battery are both made of aluminum-manganese alloy, it is convenient to weld the positive or negative electrode of the cylindrical secondary battery 100 to its corresponding aluminum busbar (because the same metal material is easy to weld).

[0076] This application does not impose any particular limitation on the structure of the current cutting-off device 40 for the cylindrical secondary battery 100. In one or more embodiments, the current cutting-off device 40 includes an explosion-proof plate 41 and a connecting plate 42 electrically connected to each other. The explosion-proof plate 41 is electrically connected to the first electrode terminal 30, and the connecting plate 42 is electrically connected to the electrode assembly 20. The explosion-proof plate 41 is configured to flip relative to the connecting plate 42 when the gas pressure inside the housing 10 reaches a first threshold, thereby disconnecting the electrical connection between the explosion-proof plate 41 and the connecting plate 42, and thus disconnecting the first electrode terminal 30 from the electrode assembly 20. After the gas pressure inside the cylindrical secondary battery housing 10 rises to the first threshold, the current in the positive and negative circuits of the cylindrical secondary battery 100 is disconnected, improving the safety of the cylindrical secondary battery 100.

[0077] Figure 5 for Figure 4 Enlarged view of A in the diagram, as shown Figure 5As shown, this application does not impose any particular limitation on the structure of the connecting plate 42 of the cylindrical secondary battery 100. In one or more embodiments, the connecting plate 42 includes a first portion 421 and a second portion 422 that are interconnected. The first portion 421 surrounds the second portion 422. The first portion 421 is connected to the electrode assembly 20, and the second portion 422 is connected to the explosion-proof sheet 41. This application does not impose any particular limitation on the structure of the explosion-proof sheet 41 of the cylindrical secondary battery 100. In one or more embodiments, the explosion-proof sheet 41 includes a third portion 411 and a fourth portion 412 that are interconnected. Along the axial direction Y of the cylindrical secondary battery, the projection of the fourth portion 412 surrounds the projection of the third portion 411. The third portion 411 and the second portion 422 are connected, and the fourth portion 412 is connected to the first electrode terminal 30.

[0078] When the cylindrical secondary battery 100 experiences a short circuit or high temperature, high-pressure gas is generated inside the casing 10. When the gas pressure inside the casing 10 reaches a first threshold, the third part 411 of the explosion-proof sheet 41 flips relative to the connecting plate 42 under the action of the high-pressure gas. The second part 422 of the connecting plate 42, which is connected to the third part 411, is carried away from the first part 421 of the connecting plate 42 by the third part 411 under the tension of the third part 411, and breaks off from the first part 421 of the connecting plate 42. The electrical connection between the connecting plate 42 and the explosion-proof sheet 41 is disconnected, thereby forming an open circuit inside the cylindrical secondary battery 100 and reducing the probability of severe situations such as smoke or fire.

[0079] Figure 6 This is a schematic diagram of the connection plate 42 of a cylindrical secondary battery 100 according to one embodiment of this application. Figure 7 This is a cross-sectional view of the connecting plate 42 of a cylindrical secondary battery 100 according to one embodiment of this application, as shown below. Figure 5 , Figure 6 and Figure 7 As shown, in one or more embodiments, the first part 421 is provided with a vent 4211. When the cylindrical secondary battery 100 experiences a short circuit or high temperature externally, the high-pressure gas inside the casing 10 passes through the vent 4211 and applies pressure to the explosion-proof sheet 41, causing the explosion-proof sheet 41 to rapidly rotate relative to the connecting plate 42. In one or more embodiments, there are at least two vents 4211, arranged around the axis L0.

[0080] This application does not impose any particular limitation on the thickness of the first portion 421 and the second portion 422 of the connecting plate 42, as long as the inventive purpose of this application is met. In one or more embodiments, along the axial direction Y of the cylindrical secondary battery 100, the thickness of the first portion 421 is H1, the thickness of the second portion 422 is H2, and 0.3≤H2 / H1≤0.8. For example, H2 / H1 can be: 0.3, 0.32, 0.34, 0.36, 0.38, 0.4, 0.42, 0.44, 0.46, 0.48, 0.5, 0.52, 0.54, 0.56, 0.58, 0.6, 0.62, 0.64, 0.66, 0.68, 0.7, 0.72, 0.74, 0.76, 0.78, 0.8, or a range consisting of any two values ​​in between.

[0081] In one or more embodiments, 0.1mm ≤ H1 ≤ 0.5mm. For example, H1 can be: 0.1mm, 0.12mm, 0.14mm, 0.16mm, 0.18mm, 0.2mm, 0.22mm, 0.24mm, 0.26mm, 0.28mm, 0.3mm, 0.32mm, 0.34mm, 0.36mm, 0.38mm, 0.4mm, 0.42mm, 0.44mm, 0.46mm, 0.48mm, 0.5mm, or a range consisting of any two values ​​in between.

[0082] In one or more embodiments, 0.03mm ≤ H2 ≤ 0.4mm, for example, H2 can be: 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0. 2mm, 0.21mm, 0.22mm, 0.23mm, 0.24mm, 0.25mm, 0.26mm, 0.27mm, 0.28mm, 0.29mm, 0.3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, 0.36mm, 0.37mm, 0.38mm, 0.39mm, 0.4mm, or a range of any two values ​​within these ranges.

[0083] By using the thickness ranges of H1 and H2 mentioned above, the resistance of the connecting plate 42 is relatively small and meets the current transmission capacity of the cylindrical secondary battery 100. By using the ratio range of H2 and H1 mentioned above, since the thickness of the second part 422 of the connecting plate 42 is less than the thickness of the first part 421 of the connecting plate 42, after the explosion-proof sheet 41 is flipped, the second part 422 is easily separated from the first part 421 by the flipping force of the explosion-proof sheet 41, so as to realize the rapid disconnection of the electrical connection between the connecting plate 42 and the explosion-proof sheet 41, thereby further reducing the occurrence of adverse conditions of the cylindrical secondary battery 100.

[0084] In one or more embodiments, the connecting plate 42 is welded to the explosion-proof sheet 41, with a welding area of ​​S = 0.8 mm. 2 ≤S≤4mm 2 For example, S can be 0.8mm. 2 1.0mm 2 1.2mm 2 1.4mm 2 1.6mm 2 1.8mm 2 2.0mm 2 2.2mm 2 2.4mm 2 2.6mm 2 2.8mm 2 3.0mm 2 3.2mm 2 3.4mm 2 3.6mm 2 3.8mm 2 4.0mm 2 Or it can be a range of any two values. This application does not impose any particular limitation on the shape of the weld between the connecting plate 42 and the explosion-proof sheet 41, as long as it meets the inventive purpose of this application. In one or more embodiments, the connecting plate 42 and the explosion-proof sheet 41 are laser welded, and a weld line 44 is exposed on the weld surface. The area surrounded by the weld line 44 is the weld area S. The area surrounded by the weld line 44 can be considered as the surface where the connecting plate 42 and the explosion-proof sheet 41 are electrically connected. Under this weld area S, in order to achieve good electrical connection strength and provide a stable current path for the connecting plate 42 and the explosion-proof sheet 41, it is also beneficial that when the gas pressure inside the housing 10 reaches the first threshold, the explosion-proof sheet 41 flips over and the electrical connection with the connecting plate 42 is broken relatively quickly.

[0085] In one or more embodiments, the second portion 422 of the connecting plate 42 includes a first annular groove 4221 along the axial direction Y of the cylindrical secondary battery. The projection of the first annular groove 4221 surrounds the projection of the welding line 44. The bottom of the first annular groove 4221 is thinner so that after the explosion-proof sheet 41 is flipped over, the welding surface of the second portion 422 and the explosion-proof sheet 41 is broken by the first annular groove 4221, so as to quickly disconnect the electrical connection with the first portion 421.

[0086] This application does not impose any particular limitation on the material of the connecting plate 42 of the cylindrical secondary battery 100. In one or more embodiments, the material of the connecting plate 42 includes one of steel, nickel, copper, nickel-plated copper, or a copper-nickel alloy. The negative electrode current collector of the electrode assembly 20 is typically made of copper foil. The connecting plate 42 is electrically connected to the negative electrode of the electrode assembly 20. The material selected for the connecting plate 42 includes one of steel, nickel, copper, nickel-plated copper, or a copper-nickel alloy, which results in lower resistance of the connecting plate 42 and facilitates reduction of heat generation during the operation of the cylindrical secondary battery 100. Nickel-plated copper refers to electroplating nickel onto the surface of a copper substrate. Nickel has good corrosion resistance, thus protecting the copper substrate. Using nickel-plated copper for the connecting plate 42 helps to extend the service life of the cylindrical secondary battery connecting plate 42.

[0087] Figure 8 This is a schematic diagram of the explosion-proof sheet 41 of a cylindrical secondary battery 100 according to one embodiment of this application. Figure 9 This is a cross-sectional view of the explosion-proof sheet 41 of a cylindrical secondary battery 100 according to one embodiment of this application, as shown below. Figure 5 , Figure 8 and Figure 9 As shown, this application does not impose any particular limitation on the thickness of the third portion 411 of the cylindrical secondary battery 100, as long as it meets the inventive purpose of this application. In one or more embodiments, along the axial direction Y of the cylindrical secondary battery 100, the thickness of the third portion 411 is H3, where 1.3 ≤ H3 / H2 ≤ 3. For example, H3 / H2 can be: 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, or a range consisting of any two values ​​in between. Using the above-mentioned ratio range of H3 and H2, since the thickness of the third part 411 of the explosion-proof sheet 41 is greater than the thickness of the second part 422 of the connecting plate 42, after the explosion-proof sheet 41 is flipped, the third part 411 has good strength and carries the second part 422 and the first part 421 to separate, thereby realizing the disconnection of the electrical connection between the connecting plate 42 and the explosion-proof sheet 41.

[0088] In one or more embodiments, 0.039mm ≤ H3 ≤ 1.2mm, for example, H3 can be: 0.039mm, 0.04mm, 0.06mm, 0.08mm, 0.1mm, 0.12mm, 0.14mm, 0.16mm, 0.18mm, 0.2mm, 0.22mm, 0.24mm, 0.26mm, 0.28mm, 0.3mm, 0.32mm, 0.34mm, 0.36mm, 0.38mm, 0.4mm, 0.42mm, 0.44mm, 0.46mm, 0.48mm, 0.5mm, 0.52mm, 0.54mm, 0.56mm, 0.58mm, 0.6mm, 0.62mm, 0.6 4mm, 0.66mm, 0.68mm, 0.7mm, 0.72mm, 0.74mm, 0.76mm, 0.78mm, 0.8mm, 0.82mm, 0.84mm, 0.86mm, 0.88mm, 0.9mm, 0.92mm, 0.94mm, 0.96mm, 0.98mm, 1.0mm, 1.02mm, 1.04mm, 1.06mm, 1.08mm, 1.1mm, 1.12mm, 1.14mm, 1.16mm, 1.18mm, 1.2mm, or a range of any two values ​​within these ranges.

[0089] In one or more embodiments, along the axial direction Y of the cylindrical secondary battery, the cylindrical secondary battery includes a first insulating member 43, at least a portion of which is disposed between a first portion 421 and a fourth portion 412. The thickness of this portion of the first insulating member 43, i.e., the thickness of the first insulating member 43 disposed between the first portion 421 and the fourth portion 412, is H4.

[0090] In one or more embodiments, 0.3mm ≤ H4 ≤ 0.7mm. For example, H4 can be: 0.3mm, 0.32mm, 0.34mm, 0.36mm, 0.38mm, 0.4mm, 0.42mm, 0.44mm, 0.46mm, 0.48mm, 0.5mm, 0.52mm, 0.54mm, 0.56mm, 0.58mm, 0.6mm, 0.62mm, 0.64mm, 0.66mm, 0.68mm, 0.7mm, or a range of any two values ​​in between. The range of values ​​for H4 is beneficial for providing good insulation between the first part 421 and the fourth part 412.

[0091] In one or more embodiments, 1.5 ≤ H4 / H2 ≤ 5. For example, H4 / H2 can be: 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, or a range consisting of any two values ​​in between. In this embodiment of the solution, the ratio range of H4 and H2 is adopted. Since the ratio of the thickness of the first insulating member 43 to the thickness of the second part 422 is 1.5≤H4 / H2≤5, after the explosion-proof sheet 41 is flipped, if the second part 422 produces free separation residue during the breakage process with the first part 421, the residue will fall between the first part 421 and the fourth part 412. Since the thickness of the first insulating member 43 is greater than the thickness of the second part 422, the thickness of the residue is less than the distance between the first part 421 and the fourth part 412. The residue is not likely to be electrically connected to the first part 421 and the fourth part 412 at the same time, thus short-circuiting the explosion-proof sheet 41 and the connecting plate 42. If the value of H4 / H2 is too large, it will easily lead to an increase in the length of the cylindrical secondary battery 100, resulting in a loss of energy density.

[0092] In one or more embodiments, the fourth portion 412 of the explosion-proof sheet 41 includes a second annular groove 4121 along the axial direction Y of the cylindrical secondary battery, the projection of the second annular groove 4121 surrounding the projection of the third portion 411. The portion of the fourth portion 412 within the second annular groove 4121 and the third portion 411 form a flip body 413.

[0093] When the air pressure inside the housing 10 reaches the first threshold, the flipping body 413 flips relative to the connecting plate 42. The explosion-proof plate 41 is configured such that when the air pressure inside the housing 10 reaches the second threshold, the second annular groove 4121 breaks to form an exhaust port, so that the gas inside the housing 10 is discharged to the outside of the housing 10 through the exhaust port.

[0094] In one or more embodiments, the second annular groove 4121 is not a closed ring, so that after the second annular groove 4121 breaks, the flipped body 413 is not easily separated from the fourth part 412, reducing the splashing of residue to the external environment when the cylindrical secondary battery 100 is depressurized.

[0095] In one or more embodiments, the second threshold is P2, where 1.9 MPa ≤ P2 ≤ 2.5 MPa. For example, P2 can be: 1.90 MPa, 1.92 MPa, 1.94 MPa, 1.96 MPa, 1.98 MPa, 2.00 MPa, 2.02 MPa, 2.04 MPa, 2.06 MPa, 2.08 MPa, 2.10 MPa, 2.12 MPa, 2.14 MPa, 2.16 MPa. The pressure range is defined as follows: 2.18 MPa, 2.20 MPa, 2.22 MPa, 2.24 MPa, 2.26 MPa, 2.28 MPa, 2.30 MPa, 2.32 MPa, 2.34 MPa, 2.36 MPa, 2.38 MPa, 2.40 MPa, 2.42 MPa, 2.44 MPa, 2.46 MPa, 2.48 MPa, 2.50 MPa, or any two values ​​within this range. When the internal pressure of the cylindrical secondary battery 100 rises to the range of P2 due to an external short circuit or high temperature environment, the second annular groove 4121 of the explosion-proof plate 41 breaks to form a vent, facilitating the discharge of high-pressure gas from the casing 100, reducing the probability of explosion or fire of the cylindrical secondary battery 100, and improving the safety of the secondary battery.

[0096] This application does not impose any particular limitation on the material of the explosion-proof sheet 41 of the cylindrical secondary battery 100. In one or more embodiments, the material of the explosion-proof sheet 41 includes one of steel, nickel, copper, copper plated with nickel, or copper-nickel alloy, so that the resistance of the connecting plate 42 is small, which makes it easier to reduce the heat generated during the operation of the cylindrical secondary battery 100.

[0097] In one or more embodiments, the explosion-proof sheet 41 is made of the same material as the connecting plate 42, which facilitates the welding of the explosion-proof sheet 41 and the connecting plate 42.

[0098] Similarly, the explosion-proof sheet 41 is made of copper plated with nickel, which helps to improve the service life of the explosion-proof sheet 41 of the cylindrical secondary battery 100.

[0099] The copper used in these embodiments is pure copper, also known as red copper, with a copper content of 99.5% or higher. The nickel used in the above embodiments is pure nickel, with a nickel content of 99.5% or higher. In one or more embodiments, both the explosion-proof sheet 41 and the connecting plate 42 are made of copper. Copper has low resistance, which helps reduce the resistance of the cylindrical secondary battery 100, and also helps reduce the heat generated by the cylindrical secondary battery 100 during current output.

[0100] In one or more embodiments, the explosion-proof sheet 41 and the connecting plate 42 are both made of copper plated with nickel, which facilitates welding and also helps to improve the rust resistance of the explosion-proof sheet 41 and the connecting plate 42 of the cylindrical secondary battery.

[0101] As the length of the cylindrical secondary battery 100 increases, its size also increases, and its capacity can be increased accordingly. The inventors noted that, unlike smaller cylindrical secondary batteries, larger cylindrical secondary batteries generate more heat and have a relatively higher internal temperature when they experience failure and heat generation.

[0102] like Figure 5 As shown, in one or more embodiments, the material of the first insulating member 43 includes ceramic. When the gas pressure inside the housing 10 reaches a first threshold, the explosion-proof sheet 41 flips over and disconnects from the connecting plate 42. Because ceramic has a high melting point and is not easily melted, it helps to maintain good insulation performance in the high-temperature environment inside the large-capacity cylindrical secondary battery 100. This maintains good insulation between the first part 421 of the connecting plate 42 and the fourth part 412 of the explosion-proof sheet 41, reducing the probability that the first insulating member 43 will melt at high temperature, causing the first part 421 of the connecting plate 42 and the fourth part 412 of the explosion-proof sheet 41 to become electrically connected, resulting in the failure of the current cutting-off device 40 to disconnect.

[0103] In one or more embodiments, the ceramic includes oxide ceramics or non-oxide ceramics; oxide ceramics include at least one of Al2O3, ZrO, MgO, CaO, B2O3, ThO2, Cr2O3, SiO2, BeO, and 3Al2O3·2SiO2; non-oxide ceramics include at least one of carbide ceramics, boride ceramics, nitride ceramics, or silicide ceramics. The above materials have high melting points and are not easily melted, which is beneficial for maintaining good insulation performance in the high-temperature internal environment of the large-capacity cylindrical secondary battery 100.

[0104] This application does not impose any particular limitation on the melting point of the first insulating element 43, as long as the inventive purpose of this application is achieved. In one or more embodiments, the melting point of the first insulating element 43 is t, where t ≥ 300℃. For example, t can be: 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, 1100℃, 1150℃, 1200℃, 1250℃, 1300℃, 1350℃, 1400℃, 1450℃, 1500℃, or a range consisting of any two values ​​in between. The first insulating element 43 has a high melting point and is not easily melted in high-temperature environments. This helps the first insulating element 43 maintain good insulation between the first part 421 and the fourth part 412, reducing the risk of failure of the current cutting-off device 40.

[0105] In one or more embodiments, t ≥ 500℃. For example, t can be: 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, 1100℃, 1150℃, 1200℃, 1250℃, 1300℃, 1350℃, 1400℃, 1450℃, 1500℃, or a range of any two values ​​in between. The first insulating element 43 has a higher melting point and can withstand higher temperatures. It is less likely to melt in high-temperature environments, which helps the first insulating element 43 maintain good insulation between the first part 421 and the fourth part 412, reducing the risk of failure of the current cutting-off device 40.

[0106] In one or more embodiments, t ≥ 800℃. For example, t can be: 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, 1100℃, 1150℃, 1200℃, 1250℃, 1300℃, 1350℃, 1400℃, 1450℃, 1500℃, or a range of any two values ​​in between. The first insulating element 43 has a higher melting point and can withstand higher temperatures. It is less likely to melt in high-temperature environments, which helps the first insulating element 43 maintain good insulation between the first part 421 and the fourth part 412, reducing the risk of failure of the current cutting-off device 40.

[0107] Figure 10 This is a schematic diagram of the structure of the first insulating member 43 of a cylindrical secondary battery 100 according to one embodiment of this application. Figure 11 This is a cross-sectional view of the first insulating member 43 of a cylindrical secondary battery 100 according to one embodiment of this application, as shown below. Figure 5 , Figure 10 and Figure 11 As shown, the first insulating member 43 includes a fifth part 431 and a sixth part 432. The fifth part 431 surrounds the sixth part 432 along the axial direction Y of the cylindrical secondary battery 100. The sixth part 432 is insulatingly connected to the first part 421 of the connecting plate 42 and the fourth part 412 of the explosion-proof sheet 41 along the radial direction X of the cylindrical secondary battery 100. The fifth part 431 is insulatingly connected to the top wall 11 and the explosion-proof sheet 41.

[0108] Figure 12 This is a schematic diagram of the support structure for a cylindrical secondary battery according to one embodiment of this application. Figure 13 This is a cross-sectional structural schematic diagram of the support structure of a cylindrical secondary battery according to one embodiment of this application, as shown below. Figure 4 , Figure 12 and Figure 13As shown, in one or more embodiments, the cylindrical secondary battery 100 provided by the present invention further includes: a support member 50; the housing 10 includes a top wall 11, and the first electrode terminal 30 is insulatedly connected to the top wall 11; the support member 50 is disposed between the electrode assembly 20 and the top wall 11, and the support member 50 supports the electrode assembly 20, which is beneficial to suppress the movement of the electrode assembly 20 and improve the service life of the cylindrical secondary battery 100.

[0109] This application does not impose any particular restrictions on the structure of the support member 50, as long as the inventive purpose of this application is achieved. Figure 3 , Figure 4 , Figure 5 , Figure 12 and Figure 13 As shown, in one or more embodiments, the support member 50 includes a first limiting part 52; the top wall 11 includes a second limiting part 111. The first limiting part 52 and the second limiting part 111 cooperate to form a relative limiting between the support member 50 and the top wall 11, which is beneficial to improving the positional stability of the support member 50 inside the cylindrical secondary battery 100.

[0110] In one or more embodiments, the first limiting part 52 includes a first protrusion 521, and the second limiting part 111 includes an annular groove 1111. The annular groove 1111 is configured such that the first protrusion 521 is disposed in the annular groove 1111. The support member 50 and the top wall 11 can rotate relative to each other around the axis L0 of the cylindrical secondary battery 100. During the assembly process between the support member 50 and the top wall 11, the first protrusion 521 can be disposed at any position in the annular groove 1111, and the support member 50 and the top wall 11 can be rotatably connected around the axis L0 of the cylindrical secondary battery 100. When the limiting of both the support member 50 and the top wall 11 is achieved, the assembly of the support member 50 and the top wall 11 is facilitated.

[0111] In one or more embodiments, the difference from the above embodiments is that the first limiting portion 52 includes an annular groove 1111, and the second limiting portion 111 includes a first protrusion 521.

[0112] In one or more embodiments, the first protrusion 521 is an annular protrusion, which is rotatably disposed in the annular groove 1111. During the assembly process between the support member 50 and the top wall 11, the annular protrusion is inserted into the annular groove 1111, so that the support member 50 and the top wall 11 can be rotatably connected to each other around the axis L0 of the cylindrical secondary battery 100, which further facilitates the assembly of the support member 50 and the top wall 11.

[0113] Figure 14 This is a schematic diagram of the current collector of a cylindrical secondary battery according to one embodiment of this application. In one or more embodiments, such as Figure 4 , Figure 12 , Figure 13 and Figure 14 As shown, the cylindrical secondary battery 100 provided in this embodiment of the invention further includes: a current collector 60, which is electrically connected to the electrode assembly 20, and a portion of the current collector 60 is disposed between the electrode assembly 20 and the support member 50; the support member 50 includes a through hole 51, a portion of which is disposed in the through hole 51 and electrically connected to the current collector 60. The support member 50 supports the current collector 60, which helps to improve the positional stability of the current collector 60. The portion of the current cut-off device 40 is disposed in the through hole 51 of the support member 50, which helps the support member 50 to limit the current cut-off device 40 in the radial direction of the cylindrical secondary battery 100.

[0114] In one or more embodiments, the collector 60 includes an electrically connected substrate 61 and a stack 62, the substrate 61 being electrically connected to the electrode assembly 20 and the stack 62 being electrically connected to the current interruption device 40, so that the collector 60 is electrically connected to the electrode assembly 20 and the current interruption device 40.

[0115] In one or more embodiments, such as Figure 3 , Figure 4 , Figure 5 , Figure 12 and Figure 13 As shown, the support member 50 includes a first surface 50a facing the electrode assembly 20. The first surface 50a is provided with a second protrusion 53, which is in contact with the current collector 60 to limit the current collector 60 and improve the positional stability of the current collector 60 inside the cylindrical secondary battery 100.

[0116] In one or more embodiments, there are at least two second protrusions 53 surrounding the axis L0 of the cylindrical secondary battery 100. For example, there are two second protrusions 53, which are disposed on both sides of the axis L0 of the cylindrical secondary battery 100. The two second protrusions 53 are respectively in contact with the base 61 of the current collector 60, which further improves the positional stability of the current collector 60 inside the cylindrical secondary battery 100.

[0117] This application does not impose any particular restrictions on the structure of the second protrusion 53. In one or more embodiments, the second protrusion 53 is a cylinder, a rectangular cylinder, or an arc-shaped cylinder, etc.

[0118] In one or more embodiments, the second protrusion 53 is a solid structure to provide high-strength support for the collector plate 60.

[0119] Unlike the solid structure of the second protrusion 53 in the above embodiments, in one or more embodiments, the support member 50 includes a second surface 50b facing away from the electrode assembly 20. The second surface 50b is provided with a groove 54 extending into the second protrusion 53. The groove 54 extends from the second surface 50b into the second protrusion 53, which helps to reduce the amount of material used in the support member 50, reduce the weight of the cylindrical secondary battery 100, and increase the mass energy density of the cylindrical secondary battery 100.

[0120] In one or more embodiments, the groove 54 is provided with a second through hole 55, which connects the second surface 50b of the support member 50 and the first surface 50a of the support member 50. During the use of the cylindrical secondary battery 100, if a small amount of electrolyte at the electrode assembly 20 position enters the groove 54 from between the second surface 50b and the top wall 11 of the support member 50, the electrolyte entering the groove 54 can easily flow back to the electrode assembly 20 position through the second through hole 55, thereby reducing the probability that the electrolyte will remain in the groove 54 and improving the utilization rate of the electrolyte.

[0121] In one or more embodiments, when the second protrusion 53 is at least two around the axis L0 of the cylindrical secondary battery 100, correspondingly, the groove 54 is at least two around the axis L0 of the cylindrical secondary battery 100, each groove 54 extending from the second surface 50b into the corresponding second protrusion 53.

[0122] In one or more embodiments, at least two first protrusions 521 and at least two grooves 54 are arranged alternately around the axis L0 of the cylindrical secondary battery 100, and adjacent first protrusions 521 and grooves 54 are connected to improve the space utilization of the support 50 (it is difficult to arrange the first protrusions 521 due to the portion where the grooves 54 are arranged).

[0123] This application does not impose any particular limitation on the material of the support member 50, as long as the inventive purpose of this application is achieved. In one or more embodiments, the material of the support member 50 includes an insulating material, and the support member 50 is an insulating support member. The support member 50 is disposed between the collector plate 60 and the top wall 11, which is beneficial to maintaining the insulation between the collector plate 60 and the top wall 11.

[0124] In one or more embodiments, the material of the support member 50 includes at least one of polyphthalamide, polyimide, or polyetheretherketone. Polyphthalamide, polyimide, or polyetheretherketone have the advantages of high temperature resistance, corrosion resistance, and high strength, which are beneficial to improving the service life of the support member 50.

[0125] In one or more embodiments, the electrode assembly 20 includes a wound electrode assembly 20. In one or more embodiments, along the axial direction Y, the two ends of the electrode assembly 20 are a first flattened portion (not shown) and a second flattened portion (not shown), respectively, and the cylindrical secondary battery 100 is a full-tab battery.

[0126] In one or more embodiments, the cylindrical secondary battery 100 provided by the present invention can be cyclically charged and discharged to facilitate multiple uses. This application does not particularly limit the type of cylindrical secondary battery 100, which may include any device in which an electrochemical reaction occurs. In one or more embodiments, the cylindrical secondary battery 100 includes, but is not limited to, lithium-ion cylindrical secondary batteries to achieve higher volumetric energy density; for example, lithium-ion cylindrical secondary batteries include, but are not limited to, lithium cobalt oxide secondary batteries, ternary lithium secondary batteries, lithium iron phosphate secondary batteries, or lithium manganese oxide secondary batteries.

[0127] In the above embodiment, the cylindrical secondary battery 100 is a full-tab battery, and the electrode assembly 20 is formed by flattening the two ends along the axial direction Y to form a first flattened portion (not shown) and a second flattened portion (not shown), and the first flattened portion and the second flattened portion have different polarities.

[0128] Secondly, this application provides a battery pack 200. Figure 15 This is a schematic diagram of the structure of the battery pack 200 provided in the embodiments of this application, as shown below. Figure 15 As shown, the battery pack 200 includes a cylindrical secondary battery 100 according to any of the above embodiments. There is at least one cylindrical secondary battery 100. In one or more embodiments, there are multiple cylindrical secondary batteries 100, which may be connected in series or in parallel, or a combination of series and parallel connections.

[0129] Thirdly, this application provides an electrical device 300, including the cylindrical secondary battery 100 or battery pack 200 of any of the above embodiments.

[0130] In one or more embodiments, Figure 16 This is a schematic diagram of the structure of the first type of electrical device provided in the embodiments of this application, as shown below. Figure 16 As shown, the power-consuming device 300 includes the battery pack 200 in the above embodiment, and the battery pack 200 includes the cylindrical secondary battery 100 in the above embodiment.

[0131] In one or more embodiments, Figure 17 This is a schematic diagram of the structure of the second type of electrical device provided in the embodiments of this application, as shown below. Figure 17 As shown, the electrical device 300 includes the cylindrical secondary battery 100 in the above embodiment.

[0132] This application does not specifically limit the electrical device, which includes electrical devices known in the prior art. For example, electrical devices include, but are not limited to, computers, smartphones, backup power supplies, two-wheeled vehicles, drones, power tools, or energy storage devices.

[0133] Example

[0134] <Preparation of Cylindrical Secondary Cells>

[0135] The positive electrode, separator, and negative electrode are stacked sequentially, with the separator positioned between the positive and negative electrodes to provide insulation. The resulting electrode assembly is then wound. This wound electrode assembly is placed within an aluminum-manganese alloy casing, and a current cutoff device and a first electrode terminal are assembled to form a cylindrical secondary battery. The positive electrode is coated with NCM811 as the positive active material, and the negative electrode is coated with natural graphite as the negative active material. The positive electrode of the assembly is electrically connected to the casing, and the negative electrode is electrically connected to the first electrode terminal. The first insulating component is made of zirconia ceramic. The cylindrical secondary battery has a diameter D of 35 mm and a length L of 205 mm.

[0136] Comparative Example

[0137] Except for the material of the first insulating element, which is thermoplastic polyester (Polyethylene terephthalate, abbreviated as PET), the rest are the same as in the example.

[0138] Short circuit test method:

[0139] A 5 milliohm resistor is connected between the top wall 11 of the cylindrical secondary battery and the first electrode terminal 30 to form an external short circuit, and temperature sensing wires are attached to the top wall 11 and the first electrode terminal 30 to measure the temperature.

[0140] Short circuit test:

[0141] The cylindrical secondary battery of the embodiment and the cylindrical secondary battery of the comparative example were subjected to the above short-circuit test method in sequence.

[0142] In the embodiment, the current cut-off device 40 disconnects approximately 32 seconds after the cylindrical secondary battery is installed, and the cylindrical secondary battery does not catch fire or emit smoke. A simulation experiment using the temperatures of the top wall 11 and the first electrode terminal 30 revealed that the temperature at the current cut-off device 40 inside the cylindrical secondary battery was 281°C. Upon disassembling the cylindrical secondary battery, it can be seen that the connecting plate 42 has been broken, and the first insulating member 43 between the explosion-proof sheet 41 and the outer periphery of the connecting plate 42 is in good condition.

[0143] The cylindrical secondary battery in the comparative model smoked and caught fire after about 20 seconds. Simulations using the temperatures of the top wall 11 and the first electrode terminal 30 showed that the temperature at the current cutoff device 40 inside the cylindrical secondary battery was 278°C. Upon disassembling the cylindrical secondary battery, it was observed that the first insulating component 43 had melted, and the explosion-proof sheet 41 overlapped with the outer periphery of the connecting plate 42.

[0144] Short circuit test conclusion:

[0145] Based on the short-circuit test results above, it can be seen that in the comparative cylindrical secondary battery, after approximately 20 seconds of short-circuit testing, the first insulating component 43 melted, the explosion-proof sheet 41 overlapped with the outer periphery of the connecting plate 42, and the current cutting-off device 40 failed. However, in the embodiment's cylindrical secondary battery, after approximately 32 seconds of short-circuit testing, the first insulating component 43 between the explosion-proof sheet 41 and the outer periphery of the connecting plate 42 remained intact, and the current cutting-off device 40 remained effective.

[0146] The cylindrical secondary battery in this embodiment has a low risk of failure of the current cut-off device 40.

[0147] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A cylindrical secondary battery, characterized in that, include: case; Electrode assemblies are disposed within the housing; The first electrode terminal is insulated from the housing. A current-cutting device is electrically connected to the electrode assembly and the first electrode terminal; The first electrode terminal is the negative electrode of the cylindrical secondary battery.

2. The cylindrical secondary battery according to claim 1, characterized in that, The casing serves as the positive electrode of the cylindrical secondary battery.

3. The cylindrical secondary battery according to claim 1 or 2, characterized in that, The material of the housing includes aluminum or an aluminum alloy; and / or, The material of the first electrode terminal includes aluminum or an aluminum alloy.

4. The cylindrical secondary battery according to any one of claims 1 to 3, characterized in that, The housing includes a top wall, and the first electrode terminal is insulated from the top wall; The top wall and the first electrode terminal are both made of aluminum-manganese alloy.

5. The cylindrical secondary battery according to any one of claims 1 to 4, characterized in that, The housing includes sidewalls made of an aluminum-manganese alloy.

6. The cylindrical secondary battery according to any one of claims 1 to 5, characterized in that, The current cutting-off device includes an explosion-proof plate and a connecting plate that are electrically connected to each other. The explosion-proof plate is electrically connected to the first electrode terminal, and the connecting plate is electrically connected to the electrode assembly.

7. The cylindrical secondary battery according to claim 6, characterized in that, The material of the connecting plate includes one of steel, nickel, copper, nickel-plated copper, or copper-nickel alloy; The explosion-proof sheet is made of one of the following materials: steel, nickel, copper, nickel-plated copper, or copper-nickel alloy.

8. The cylindrical secondary battery according to claim 7, characterized in that, The explosion-proof sheet and the connecting plate are both made of copper; or, the explosion-proof sheet and the connecting plate are both made of copper plated with nickel.

9. The cylindrical secondary battery according to any one of claims 6 to 8, characterized in that, The connecting plate includes a first part and a second part that are connected to each other. The first part surrounds the second part. The first part is connected to the electrode assembly, and the second part is connected to the explosion-proof sheet. The thickness of the first part is H1, and the thickness of the second part is H2, where 0.3 ≤ H2 / H1 ≤ 0.

8.

10. The cylindrical secondary battery according to claim 9, characterized in that, 0.1mm≤H1≤0.5mm.

11. The cylindrical secondary battery according to claim 9 or 10, characterized in that, The explosion-proof sheet includes a third part and a fourth part that are connected to each other along the axial direction of the cylindrical secondary battery. The projection of the fourth part surrounds the projection of the third part. The third part is connected to the second part, and the fourth part is connected to the first electrode terminal. The thickness of the third part is H3, and 1.3≤H3 / H2≤3.

12. The cylindrical secondary battery according to any one of claims 9 to 11, characterized in that, The connecting plate is welded to the explosion-proof sheet, and the welding area is S, 0.8mm. 2 ≤S≤4mm 2 .

13. The cylindrical secondary battery according to claim 11, characterized in that, The cylindrical secondary battery includes a first insulating member, at least a portion of which is disposed between the first portion and the fourth portion; The thickness of this part is H4, and 1.5≤H4 / H2≤5.

14. The cylindrical secondary battery according to claim 13, characterized in that, 0.3mm≤H4≤0.7mm.

15. The cylindrical secondary battery according to claim 13 or 14, characterized in that, The material of the first insulating element includes ceramic.

16. The cylindrical secondary battery according to claim 15, characterized in that, The ceramics include oxide ceramics or non-oxide ceramics; The oxide ceramics include at least one of the following: Al2O3, ZrO, MgO, CaO, B2O3, ThO2, Cr2O3, SiO2, BeO, and 3Al2O3·2SiO2; The non-oxide ceramics include at least one of carbide ceramics, boride ceramics, nitride ceramics, or silicide ceramics.

17. The cylindrical secondary battery according to any one of claims 13 to 16, characterized in that, The melting point of the first insulating component is t, where t ≥ 300℃.

18. The cylindrical secondary battery according to claim 17, characterized in that, t≥500℃。 19. The cylindrical secondary battery according to claim 18, characterized in that, t≥800℃。 20. The cylindrical secondary battery according to any one of claims 1 to 19, characterized in that, Also includes: Support components; The housing includes a top wall, and the first electrode terminal is insulated from the top wall; The support is disposed between the electrode assembly and the top wall.

21. The cylindrical secondary battery according to claim 20, characterized in that, Also includes: A current collector, which is electrically connected to the electrode assembly, and a portion of the current collector is disposed between the electrode assembly and the support member; The support includes a through hole, a portion of which is disposed in the through hole and electrically connected to the current collector.

22. The cylindrical battery according to any one of claims 1 to 21, characterized in that, The current cut-off device is configured to disconnect when the gas pressure inside the housing reaches a first threshold, thereby disconnecting the electrode assembly and the first electrode terminal from electrical connection.

23. The cylindrical secondary battery according to any one of claims 1 to 22, characterized in that, The cylindrical secondary battery is a cylindrical secondary battery; The diameter of the cylindrical secondary battery is D, where 25mm ≤ D ≤ 65mm; and / or, The length of the cylindrical secondary battery is L, where 80mm ≤ L ≤ 250mm.

24. A battery pack, characterized in that, The cylindrical secondary battery includes any one of claims 1 to 23 above.

25. An electrical appliance, characterized in that, The battery pack includes the cylindrical secondary battery described in any one of claims 1 to 23 or the battery pack described in claim 24.

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