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 comprises a casing (10), an electrode assembly (20), a first electrode terminal (30), and a current interrupt device (40). The current interrupt device (40) is electrically connected to the electrode assembly (20) and the first electrode terminal (30), and the first electrode terminal (30) is a negative electrode of the cylindrical secondary battery.

Description

Cylindrical secondary battery, battery pack and electric device TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage, in particular to a cylindrical secondary battery, a battery pack and an electric device. BACKGROUND

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

[0003] The shell of a cylindrical lithium ion battery is usually made of steel to achieve application in multiple working conditions. A current interrupt device (CID) is generally arranged in the shell of the lithium ion battery. The CID is electrically connected to the positive electrode of the lithium ion battery, and the shell serves as the negative electrode. When the air pressure in the shell of the lithium ion battery is too large, the CID can disconnect the charging and discharging circuit of the lithium ion battery to provide safety protection for the lithium ion battery.

[0004] As the demand for battery capacity increases, the size of the shell also increases. In the case of a long shell size requirement, it is difficult to process the steel shell to the required length due to the low ductility of steel.

[0005] SUMMARY

[0006] The present application aims to provide a cylindrical secondary battery, a battery pack and an electric device to facilitate the preparation of a long secondary battery.

[0007] The first aspect of the present application provides a cylindrical secondary battery, comprising: a shell; an electrode assembly arranged in the shell; a first electrode terminal insulatedly connected to the shell; and a current interrupt device electrically connected to the electrode assembly and the first electrode terminal, the first electrode terminal being the negative electrode of the cylindrical secondary battery. The current interrupt device facilitates improving the safety of the secondary battery. The shell of the cylindrical secondary battery is not in a low potential environment of the negative electrode, which facilitates the selection of the shell material to facilitate the preparation of a long secondary battery.

[0008] In one or more embodiments, the shell is the positive electrode of the cylindrical secondary battery, thereby saving the electrode terminal as the positive electrode.

[0009] In one or more embodiments, the material of the shell comprises aluminum or an aluminum alloy; and / or, the material of the first electrode terminal comprises aluminum or an aluminum alloy. The material of the shell comprises aluminum or an aluminum alloy, which has good ductility and is beneficial to stretching the side wall to a longer size, facilitating the preparation of a cylindrical secondary battery with large volume and large capacity. The material of the first electrode terminal comprises aluminum or an aluminum alloy, which facilitates the welding of the positive electrode or negative electrode of the cylindrical secondary battery and the aluminum busbar.

[0010] In one or more embodiments, the shell comprises a top wall, the first electrode terminal is insulatedly connected with the top wall, and the top wall and the first electrode terminal are both made of aluminum-manganese alloy. In the case that the top wall is the positive electrode of the cylindrical secondary battery, since the positive electrode and the negative electrode of the cylindrical secondary battery are both made of aluminum-manganese alloy, the positive electrode or the negative electrode of the cylindrical secondary battery is facilitated to be welded with the aluminum busbar.

[0011] In one or more embodiments, the shell comprises a side wall, and the side wall is made of aluminum-manganese alloy. The side wall is made of aluminum-manganese alloy, which is beneficial to stretching the side wall to a longer size, and is beneficial to preparing a cylindrical secondary battery with large volume and large capacity.

[0012] In one or more embodiments, the current cut-off device comprises an explosion-proof sheet and a connecting plate which are electrically connected with each other, the explosion-proof sheet is electrically connected with the first electrode terminal, and the connecting plate is electrically connected with the electrode assembly. After the air pressure in the shell of the cylindrical secondary battery rises to a first threshold value, the explosion-proof sheet and the connecting plate are disconnected, so as to disconnect the current loop of the positive electrode and the negative electrode of the cylindrical secondary battery, and improve the safety of the secondary battery.

[0013] In one or more embodiments, the material of the connecting plate comprises one of steel, nickel, copper, copper-nickel plated nickel, and copper-nickel alloy, and the material of the explosion-proof sheet comprises one of steel, nickel, copper, copper-nickel plated nickel, and copper-nickel alloy. The connecting plate and the explosion-proof sheet are in a low potential environment of the negative electrode, and the material thereof comprises one of steel, nickel, copper, copper-nickel plated nickel, and copper-nickel alloy, which is not easy to be corroded by chemical reaction with lithium ions in the low potential environment of the negative electrode, so as to be suitable for the cylindrical secondary battery of lithium ions.

[0014] In one or more embodiments, the material of the explosion-proof sheet and the connecting plate is copper, or the material of the explosion-proof sheet and the connecting plate is copper-nickel plated. The resistance of copper is small, which is beneficial to reducing the resistance of the cylindrical secondary battery and reducing the heat generation of the cylindrical secondary battery. The copper-nickel plated has good anti-rust performance, which is beneficial to improving the welding capacity and the anti-rust performance of the explosion-proof sheet of the cylindrical secondary battery. The explosion-proof sheet and the connecting plate use the same material, which is easy to be welded.

[0015] In one or more embodiments, the connecting plate comprises a first part and a second part which are connected with each other, the first part surrounds the second part, the first part is connected with the electrode assembly, and the second part is connected with 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. Since the thickness of the second part of the connecting plate is smaller than the thickness of the first part, when the explosion-proof sheet is turned over, the second part is easy to be separated from the first part under the driving of the turning over of the explosion-proof sheet, so as to disconnect the electrical connection between the connecting plate and the explosion-proof sheet.

[0016] In one or more embodiments, 0.1mm≤H1≤0.5mm. By using the thickness range of H1, the resistance of the connecting plate is small and meets the current transmission capacity of the cylindrical secondary battery.

[0017] In one or more embodiments, the rupture disc comprises a third portion and a fourth portion connected to each other, a projection of the fourth portion encircles a projection of the third portion along an axial direction of the cylindrical secondary battery, the third portion is connected to the second portion, the fourth portion is connected to the first electrode terminal, a thickness of the third portion is H3, and 1.3≤H3 / H2≤3. Since the thickness of the third portion of the rupture disc is greater than the thickness of the second portion of the connecting plate, the third portion has good strength, which is conducive to the rupture disc driving the second portion and the first portion to separate when the rupture disc is turned over, so as to realize the disconnection of the connecting plate and the rupture disc.

[0018] In one or more embodiments, the connecting plate is welded to the rupture disc, a welding area is S, and 0.8mm 2 ≤S≤4mm 2 . The welding area S is conducive to the relatively rapid disconnection of the connecting plate and the rupture disc after the rupture disc is turned over when the air pressure in the shell reaches the first threshold, while achieving good electrical connection strength of the connecting plate and the rupture disc.

[0019] In one or more embodiments, the cylindrical secondary battery comprises a first insulating member, at least a part of the first insulating member is arranged between the first portion and the fourth portion, a thickness of the first insulating member arranged between the first portion and the fourth portion is H4, and 1.5≤H4 / H2≤5. After the rupture disc is turned over, if the second portion generates a free separated residue in the process of being disconnected from the first portion, since the thickness of the first insulating member is greater than the thickness of the second portion, the residue falls between the first portion and the fourth portion and is not easy to be electrically connected to the first portion and the fourth portion at the same time, thereby short-circuiting the rupture disc and the connecting plate; if H4 / H2 is too large, the length of the cylindrical secondary battery is easy to increase, and the energy density is lost.

[0020] In one or more embodiments, 0.3mm≤H4≤0.7mm, and the value range of H4 is conducive to maintaining good insulation performance between the first portion and the fourth portion at a relatively reasonable thickness.

[0021] In one or more embodiments, the material of the first insulating member comprises ceramic. The melting point of ceramic is relatively high and is not easy to melt, which is conducive to maintaining good insulation performance between the first portion and the fourth portion in a high-temperature environment inside the cylindrical secondary battery with large capacity, thereby reducing the risk of CID failure.

[0022] In one or more embodiments, the ceramic comprises an oxide ceramic or a non-oxide ceramic; the oxide ceramic comprises at least one of Al2O3, ZrO, MgO, CaO, B2O3, ThO2, Cr2O3, SiO2, BeO, 3Al2O3·2SiO2; the non-oxide ceramic comprises at least one of a carbide ceramic, a boride ceramic, a nitride ceramic, or a silicide ceramic. The above-mentioned materials have high melting points and are not easy to melt, which is conducive to maintaining good insulation performance between the first portion and the fourth portion in a high-temperature environment inside the cylindrical secondary battery, and reducing the risk of CID failure.

[0023] In one or more embodiments, the first insulating piece has a melting point t, t≥300℃. The first insulating piece has a high melting point and is not easy to melt in a high-temperature environment, which is conducive to the first insulating piece maintaining good insulation between the first portion and the fourth portion, and reducing the risk of CID failure.

[0024] In one or more embodiments, t≥500℃. The first insulating piece has a higher melting point and is more difficult to melt in a high-temperature environment, which is conducive to the first insulating piece maintaining good insulation between the first portion and the fourth portion, and reducing the risk of CID failure.

[0025] In one or more embodiments, t≥800℃. The first insulating piece has a higher melting point and is more difficult to melt in a high-temperature environment, which is conducive to the first insulating piece maintaining good insulation between the first portion and the fourth portion, and reducing the risk of CID failure.

[0026] In one or more embodiments, further comprising: a support; the shell comprises a top wall, and the first electrode terminal is insulatedly connected to the top wall; the support is arranged between the electrode assembly and the top wall, and the support supports the electrode assembly, which is conducive to inhibiting the movement of the electrode assembly and improving the service life of the cylindrical secondary battery.

[0027] In one or more embodiments, further comprising: a current collector, the current collector is electrically connected to the electrode assembly, and part of the current collector is arranged between the electrode assembly and the support; the support comprises a through hole, and part of the current interrupting device is arranged in the through hole and electrically connected to the current collector. The support supports the current collector, which is conducive to improving the positional stability of the current collector. Part of the current interrupting device is arranged in the through hole of the support, which is conducive to the support limiting the current interrupting device in the radial direction of the cylindrical secondary battery.

[0028] In one or more embodiments, the current interrupting device is configured to be disconnected when the air pressure in the shell reaches a first threshold value, so as to disconnect the electrode assembly and the first electrode terminal, thereby disconnecting the current loop of the positive electrode and the negative electrode of the cylindrical secondary battery, and improving the safety of the secondary battery.

[0029] In one or more embodiments, the cylindrical secondary battery is a cylindrical secondary battery, a diameter of the cylindrical secondary battery is D, 25mm≤D≤65mm; and / or, a length of the cylindrical secondary battery is L, 80mm≤L≤250mm. The cylindrical secondary battery of the present embodiment has a long size and a large capacity, so as to be suitable for use in high-power or large battery packs and electric devices.

[0030] The second aspect of the present application provides a battery pack comprising the cylindrical secondary battery of any one of the above embodiments.

[0031] The third aspect of the present application provides an electric device comprising the cylindrical secondary battery or the battery pack of any one of the above embodiments.

[0032] The beneficial effects of the present application are as follows:

[0033] The present application provides a cylindrical secondary battery, a battery pack and an electric device. The cylindrical secondary battery comprises a shell, an electrode assembly, a first electrode terminal and a current cut-off device. The current cut-off device is electrically connected to the electrode assembly and the first electrode terminal, so as to improve the safety of the secondary battery. In addition, compared with the prior art, in the embodiments of the present application, the first electrode terminal is the negative electrode of the cylindrical secondary battery, and the first electrode terminal is insulatedly connected to the shell. Therefore, the shell is not in a low potential environment of the negative electrode, and some materials with higher ductility (such as aluminum materials) are not easy to be corroded. Therefore, the shell can be made of a material with higher ductility, so as to facilitate the preparation of a long-size secondary battery. BRIEF DESCRIPTION OF DRAWINGS

[0034] The accompanying drawings, which are included to provide a further understanding of the present application and are incorporated in and constitute a part of this application, illustrate embodiments of the present application and serve to explain the present application. Features of the present application, both as to organization and method of operation, together with an understanding of the same, can be best understood by reference to the following detailed description, taken in connection with the accompanying drawings.

[0035] FIG. 1 is a structural schematic diagram of a cylindrical secondary battery according to an embodiment of the present application;

[0036] FIG. 2 is an exploded structural schematic diagram of the cylindrical secondary battery according to an embodiment of the present application;

[0037] FIG. 3 is a partial exploded sectional structural schematic diagram of the cylindrical secondary battery according to an embodiment of the present application;

[0038] FIG. 4 is a partial sectional structural schematic diagram of the cylindrical secondary battery according to an embodiment of the present application;

[0039] FIG. 5 is an enlarged view of A in FIG. 4;

[0040] FIG. 6 is a structural schematic diagram of a connecting plate of the cylindrical secondary battery according to an embodiment of the present application;

[0041] FIG. 7 is a cross-sectional structural schematic view of a connecting plate of a cylindrical secondary battery according to an embodiment of the present application;

[0042] FIG. 8 is a structural schematic view of an explosion-proof sheet of a cylindrical secondary battery according to an embodiment of the present application;

[0043] FIG. 9 is a cross-sectional structural schematic view of an explosion-proof sheet of a cylindrical secondary battery according to an embodiment of the present application;

[0044] FIG. 10 is a structural schematic view of a first insulating member of a cylindrical secondary battery according to an embodiment of the present application;

[0045] FIG. 11 is a cross-sectional structural schematic view of a first insulating member of a cylindrical secondary battery according to an embodiment of the present application;

[0046] FIG. 12 is a structural schematic view of a support member of a cylindrical secondary battery according to an embodiment of the present application;

[0047] FIG. 13 is a cross-sectional structural schematic view of a support member of a cylindrical secondary battery according to an embodiment of the present application;

[0048] FIG. 14 is a structural schematic view of a current collecting plate of a cylindrical secondary battery according to an embodiment of the present application;

[0049] FIG. 15 is a structural schematic view of a battery pack according to an embodiment of the present application;

[0050] FIG. 16 is a structural schematic view of a first power consuming device according to an embodiment of the present application;

[0051] FIG. 17 is a structural schematic view of a second power consuming device according to an embodiment of the present application.

[0052] The reference signs are as follows: housing 10, top wall 11, second limiting portion 111, annular groove 1111, side wall 12, electrode assembly 20, first electrode terminal 30, current interrupting device 40, explosion-proof sheet 41, third portion 411, fourth portion 412, second annular groove 4121, turnover body 413, connecting plate 42, first portion 421, vent hole 4211, second portion 422, first annular groove 4221, first insulating member 43, fifth portion 431, sixth portion 432, welding wire 44, support member 50, first face 50a, second face 50b, through hole 51, first limiting portion 52, first protrusion 521, second protrusion 53, groove 54, second through hole 55, current collecting plate 60, base 61, laminated layer 62; cylindrical secondary battery 100, battery pack 200, power consuming device 300; axial direction Y, radial direction X, axis L0. DETAILED DESCRIPTION

[0053] With reference to the drawings and the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application.

[0054] In the present application, unless specifically defined and limited otherwise, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium, or can be connected inside two elements. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0055] In the description of the embodiments of the present application, the technical terms "first", "second" and the like are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise specifically limited.

[0056] In this paper, the term "embodiment" means that the specific features, structures or properties described in conjunction with the embodiment can be included in at least one embodiment of the present application. The phrase appears at various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment to other embodiments. In the case of no conflict, each embodiment in the present application can be combined with each other.

[0057] In the related art, since the steel material is not easy to be corroded by lithium ions in the low potential negative electrode environment, the shell is usually made of steel material. However, the ductility of steel material is not high, and it is difficult to process and prepare long cylindrical secondary batteries. If a material with higher ductility such as aluminum material is selected to prepare the shell, the aluminum material shell will be corroded by lithium ions in the lithium ion battery in the low potential negative electrode environment. The first electrode terminal of the cylindrical secondary battery provided in the embodiments of the present application is a negative electrode, the first electrode terminal is insulatedly connected with the shell, and the shell is not a negative electrode, so that the shell is not in the low potential negative electrode environment, and it is convenient to select a material with higher ductility than steel (such as aluminum) and use a stretching process to prepare a long cylindrical secondary battery. Moreover, the cylindrical secondary battery has a CID structure, and has high safety.

[0058] The shape of the cylindrical secondary battery is not particularly limited in the present application, as long as the object of the present application is achieved. In one or more embodiments, the cylindrical secondary battery is at least one of a round cylindrical secondary battery, an elliptical cylindrical secondary battery, a polygonal secondary battery (including a secondary battery having a regular polygonal cross section or a secondary battery having an irregular polygonal cross section).

[0059] For better understanding of the present application, the cylindrical secondary battery according to an embodiment of the present application will be described in detail below.

[0060] It should be noted that the sizes of various components in the embodiments of the present application shown in the drawings, as well as the sizes of the cylindrical secondary battery, are only exemplary and should not constitute any limitation on the present application.

[0061] FIG. 1 is a structural schematic diagram of a cylindrical secondary battery according to an embodiment of the present application. As shown in FIG. 1, in a first aspect, the present application provides a cylindrical secondary battery 100, and the axis of the cylindrical secondary battery 100 is L0. The radial direction of the cylindrical secondary battery 100 is X, which is a direction in a plane perpendicular to the axis L0, pointing to the outside of the cylindrical secondary battery 100 from 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 secondary battery is D.

[0062] FIG. 2 is an exploded structural schematic diagram of a cylindrical secondary battery according to an embodiment of the present application, FIG. 3 is a partial exploded sectional structural schematic diagram of a cylindrical secondary battery according to an embodiment of the present application, and FIG. 4 is a partial sectional structural schematic diagram of a cylindrical secondary battery according to an embodiment of the present application. As shown in FIGS. 2, 3 and 4, the cylindrical secondary battery 100 includes a housing 10, an electrode assembly 20, a first electrode terminal 30 and a current cutoff device 40. The electrode assembly 20 is arranged in the housing 10; the first electrode terminal 30 is insulatedly connected with the housing 10; and the current cutoff device 40 is electrically connected with the electrode assembly 20 and the first electrode terminal 30.

[0063] The first electrode terminal 30 is a negative electrode of the cylindrical secondary battery 100.

[0064] In one or more embodiments, the current cutoff device 40 is configured to be disconnected when the air pressure in the housing 10 reaches a first threshold value, so as to disconnect the electrode assembly 20 and the first electrode terminal 30 from electrical connection.

[0065] In one or more embodiments, the first threshold value is P1, 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, 1.28 MPa, 1.3 MPa, 1.32 MPa, 1.34 MPa, 1.36 MPa, 1.38 MPa, 1.4 MPa, 1.42 MPa, 1.44 MPa, 1.46 MPa, 1.48 MPa, 1.5 MPa, 1.52 MPa, 1.54 MPa, 1.56 MPa, 1.58 MPa, 1.6 MPa, or a range between any two of the above values. When the pressure in the shell 10 of the cylindrical secondary battery 100 increases to the range of P1, the current cutoff device 40 cuts off the electrical connection between the electrode assembly 20 and the first electrode terminal 30, thereby facilitating the formation of an open circuit to the outside and improving the safety of the cylindrical secondary battery 100.

[0066] The shell 10 is not the negative electrode of the cylindrical secondary battery 100. Since the shell 10 is not in the 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.

[0067] The material of the shell 10 is not particularly limited in the present application. In one or more embodiments, the shell 10 is made of a material with high ductility, for example, in one or more embodiments, the material of the shell 10 includes aluminum or aluminum alloy, that is, the material of the shell 10 can be pure aluminum or aluminum alloy, and in one or more embodiments, the aluminum alloy includes aluminum-manganese alloy. Since pure aluminum, aluminum alloy, and aluminum-manganese alloy have good ductility, in the preparation of the shell 10, compared with the shell 10 prepared from steel, the shell 10 prepared from aluminum is easy to be prepared to the required length by stretching process, which is convenient for the preparation of long cylindrical secondary battery 100.

[0068] In one or more embodiments, the diameter of the cylindrical secondary battery 100 is D, and 25 mm≤D≤65 mm, but is not limited thereto. For example, D can be 25 mm, 27 mm, 29 mm, 31 mm, 33 mm, 35 mm, 37 mm, 39 mm, 41 mm, 43 mm, 45 mm, 47 mm, 49 mm, 51 mm, 53 mm, 55 mm, 57 mm, 59 mm, 61 mm, 63 mm, 65 mm, or a range between any two of them. In one or more embodiments, the length of the cylindrical secondary battery 100 is L, and 80 mm≤L≤250 mm, but is not limited thereto. For example, L can be 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm, 160 mm, 170 mm, 180 mm, 190 mm, 200 mm, 210 mm, 220 mm, 230 mm, 240 mm, 250 mm, or a range between any two of them. In the related art, the diameter of the cylindrical secondary battery 100 is usually small, such as a 18650 battery, a 21700 battery, or a 46800 battery. The cylindrical secondary battery 100 of the present embodiment is long in size, so as to be suitable for use in a high-power or large battery pack and a power-consuming device.

[0069] The present application does not have a particular limitation on the arrangement of the positive electrode of the cylindrical secondary battery 100. In one or more embodiments, the cylindrical secondary battery further includes a second electrode terminal (not shown) that is insulatedly connected to the housing 10 and electrically connected to the electrode assembly 20, and the second electrode terminal is the positive electrode of the cylindrical secondary battery 100. The housing 10 is neither the positive electrode nor the negative electrode of the cylindrical secondary battery 100. The cylindrical secondary battery 100 has the first electrode terminal 30 and the second electrode terminal, and is arranged at both ends of the cylindrical secondary battery 100. Since the distance is far, it is not easy for them to contact each other and short-circuit.

[0070] In one or more embodiments, different from the above-mentioned embodiments, in the present embodiment, the cylindrical secondary battery 100 does not have the 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 the second electrode terminal is not needed, the parts of the second electrode terminal are saved, the number of parts is reduced, the processing and assembly of the cylindrical secondary battery are easy, and the overall length of the battery is shortened, which is conducive to improving the energy density of the cylindrical secondary battery 100.

[0071] The material of the first electrode terminal 30 is not particularly limited, and in one or more embodiments, the material of the first electrode terminal 30 includes aluminum. The first electrode terminal 30 made of aluminum and the shell 10 made of aluminum or the shell 10 made of an aluminum alloy are used in combination. The shell 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. This facilitates welding of the positive electrode or the negative electrode of the cylindrical secondary battery to the aluminum bus bar.

[0072] In one or more embodiments, the material of the first electrode terminal 30 is not limited to aluminum, and can also include an aluminum alloy. The first electrode terminal 30 made of an aluminum alloy and the shell 10 made of aluminum or the shell 10 made of an aluminum alloy are used in combination. This also facilitates welding of the positive electrode or the negative electrode of the cylindrical secondary battery to the aluminum bus bar.

[0073] In one or more embodiments, the shell 10 includes a top wall 11, a side wall 12, and a bottom wall (not shown). The first electrode terminal 30 is insulatedly connected to the top wall 11. The material of the top wall 11 and the first electrode terminal 30 is an 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 electrically connects the top wall 11 and the bottom wall. The cylindrical secondary battery 100 is applied to a battery pack. The positive electrodes and the negative electrodes of a plurality of cylindrical secondary batteries 100 are respectively electrically connected to corresponding aluminum bus bars. Since the material of the positive electrode and the negative electrode of the cylindrical secondary battery is an aluminum-manganese alloy, it is convenient to weld the positive electrode or the negative electrode of the cylindrical secondary battery 100 to the corresponding aluminum bus bar (since the same metal material is easy to weld).

[0074] The structure of the current cutoff device 40 of the cylindrical secondary battery 100 is not particularly limited. In one or more embodiments, the current cutoff device 40 includes an explosion-proof sheet 41 and a connecting plate 42 that are electrically connected to each other. The explosion-proof sheet 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 sheet 41 is configured to flip relative to the connecting plate 42 when the air pressure inside the shell 10 reaches a first threshold value. The explosion-proof sheet 41 and the connecting plate 42 are disconnected electrically connected, so as to disconnect the first electrode terminal 30 and the electrode assembly 20 electrically connected. After the air pressure inside the cylindrical secondary battery shell 10 rises to the first threshold value, the current in the positive electrode and the negative electrode loop of the cylindrical secondary battery 100 is conveniently disconnected, and the safety of the cylindrical secondary battery 100 is improved.

[0075] Figure 5 is an enlarged view of A in Figure 4, as shown in Figure 5, the structure of the connecting plate 42 of the cylindrical secondary battery 100 is not particularly limited in the present application, in one or more embodiments, the connecting plate 42 comprises a first portion 421 and a second portion 422 connected to each other, 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 rupture disc 41. The structure of the rupture disc 41 of the cylindrical secondary battery 100 is not particularly limited in the present application. In one or more embodiments, the rupture disc 41 comprises a third portion 411 and a fourth portion 412 connected to each other, 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 is connected to the second portion 422, and the fourth portion 412 is connected to the first electrode terminal 30.

[0076] When the cylindrical secondary battery 100 is externally short-circuited or in a high-temperature environment, high-pressure gas is generated inside the casing 10, when the gas pressure inside the casing 10 reaches the first threshold value, the third portion 411 of the rupture disc 41 is flipped over relative to the connecting plate 42 under the action of the high-pressure gas, wherein the second portion 422 of the connecting plate 42 is carried away from the first portion 421 of the connecting plate 42 by the third portion 411 of the rupture disc 41 under the pulling force of the third portion 411 of the rupture disc 41 and is broken away from the first portion 421 of the connecting plate 42, the electrical connection between the connecting plate 42 and the rupture disc 41 is disconnected, thereby forming a circuit break in the cylindrical secondary battery 100, reducing the probability of occurrence of adverse conditions such as smoking or fire.

[0077] Figure 6 is a schematic view of the structure of the connecting plate 42 of the cylindrical secondary battery 100 according to an embodiment of the present application, and Figure 7 is a schematic view of the cross-sectional structure of the connecting plate 42 of the cylindrical secondary battery 100 according to an embodiment of the present application, as shown in Figures 5, 6 and 7, in one or more embodiments, the first portion 421 is provided with a vent hole 4211, when the cylindrical secondary battery 100 is externally short-circuited or in a high-temperature environment, the high-pressure gas inside the casing 10 exerts pressure on the rupture disc 41 through the vent hole 4211, causing the rupture disc 41 to quickly flip over relative to the connecting plate 42. In one or more embodiments, the vent hole 4211 is at least two and is arranged around the axis L0.

[0078] The thickness of the first portion 421 and the thickness of the second portion 422 of the connecting plate 42 are not particularly limited in the present application, as long as the object of the present application is achieved. 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, and the thickness of the second portion 422 is H2, 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 between any two of the above values.

[0079] 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 between any two of the above values.

[0080] 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 between any two of the above values.

[0081] With the thickness range of H1 and H2 as described above, the resistance of the connecting plate 42 is small and meets the current transmission capability of the cylindrical secondary battery 100, with the ratio range of H2 and H1 as described 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 rupture disc 41 is flipped, the second part 422 is easy to be separated from the first part 421 under the driving of the flipping force of the rupture disc 41, and the connecting plate 42 and the rupture disc 41 are quickly disconnected, so as to further reduce the occurrence of the adverse situation of the cylindrical secondary battery 100.

[0082] In one or more embodiments, the connecting plate 42 is welded with the rupture disc 41, and the welding area is S, 0.8mm 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 a range between any two of the above values. The application does not particularly limit the shape of the welding of the connecting plate 42 and the rupture disc 41, as long as the application purpose is met. In one or more embodiments, the connecting plate 42 and the rupture disc 41 are laser welded, and the welding line 44 is exposed on the welding surface, and the area surrounded by the welding line 44 is the welding area S. The area surrounded by the welding line 44 can be considered as the surface of the electrically connected connecting plate 42 and the rupture disc 41, and under the welding area S, the connecting plate 42 and the rupture disc 41 achieve good electrical connection strength and provide a stable current path, which is also conducive to the relatively rapid electrical disconnection of the connecting plate 42 after the rupture disc 41 is flipped when the air pressure in the shell 10 reaches the first threshold.

[0083] In one or more embodiments, the second portion 422 of the connecting plate 42 comprises a first annular groove 4221, a projection of the first annular groove 4221 along the axial direction Y of the cylindrical secondary battery 100 encircles a projection of the welding wire 44, and a groove bottom of the first annular groove 4221 is thin, so that, after the rupture disk 41 is flipped, the welding surface of the second portion 422 and the rupture disk 41 is broken by the first annular groove 4221, and the quick electrical connection between the second portion 422 and the first portion 421 is disconnected.

[0084] The material of the connecting plate 42 of the cylindrical secondary battery 100 is not particularly limited in the present application, and in one or more embodiments, the material of the connecting plate 42 comprises one of steel, nickel, copper, copper-nickel plated copper, or copper-nickel alloy. The negative current collector of the electrode assembly 20 is usually made of copper foil, and the material of the connecting plate 42 for electrical connection with the negative electrode of the electrode assembly 20 comprises one of steel, nickel, copper, copper-nickel plated copper, or copper-nickel alloy, so that the resistance of the connecting plate 42 is small, and the heat generated during the operation of the cylindrical secondary battery 100 is reduced. Copper-nickel plated copper refers to the surface of a copper substrate covered with nickel by electroplating. Nickel has good corrosion resistance, and thus can protect the copper substrate. The material of the connecting plate 42 is copper-nickel plated copper, which is beneficial to prolong the service life of the connecting plate 42 of the cylindrical secondary battery.

[0085] FIG. 8 is a structural schematic diagram of the rupture disk 41 of the cylindrical secondary battery 100 according to an embodiment of the present application, and FIG. 9 is a sectional structural schematic diagram of the rupture disk 41 of the cylindrical secondary battery 100 according to an embodiment of the present application. As shown in FIGS. 5, 8, and 9, the thickness of the third portion 411 of the rupture disk 41 is not particularly limited in the present application, as long as the purpose of the present application is achieved. In one or more embodiments, the thickness of the third portion 411 along the axial direction Y of the cylindrical secondary battery 100 is H3, and 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 between any two of the above values. By using the above range of H3 / H2, since the thickness of the third portion 411 of the rupture disk 41 is greater than the thickness of the second portion 422 of the connecting plate 42, after the rupture disk 41 is flipped, the third portion 411 has good strength and separates the second portion 422 from the first portion 421, so that the connecting plate 42 and the rupture disk 41 are disconnected in electrical connection.

[0086] 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, 0.64mm, 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 between any two of the foregoing values.

[0087] In one or more embodiments, along the axial direction Y of the cylindrical secondary battery, the cylindrical secondary battery comprises a first insulating member 43, at least a portion of the first insulating member 43 is arranged between the first portion 421 and the fourth portion 412. The thickness of the portion of the first insulating member 43, i.e. the thickness of the first insulating member 43 arranged between the first portion 421 and the fourth portion 412, is H4.

[0088] 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 between any two of the foregoing values, the range of H4 is conducive to good insulation of the first portion 421 and the fourth portion 412.

[0089] 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 between any two of the above values. In the embodiments of the present application, the ratio of the thickness of the first insulating member 43 and the thickness of the second portion 422 is 1.5≤H4 / H2≤5. After the rupture disc 41 is flipped, if the second portion 422 generates a free-standing residue during the rupture process of the first portion 421, the residue falls between the first portion 421 and the fourth portion 412. Since the thickness of the first insulating member 43 is greater than the thickness of the second portion 422, the thickness of the residue is less than the distance between the first portion 421 and the fourth portion 412, and the residue is not easily electrically connected to the first portion 421 and the fourth portion 412, thereby short-circuiting the rupture disc 41 and the connecting plate 42. If the value of H4 / H2 is too large, the length of the cylindrical secondary battery 100 increases, and the energy density is lost.

[0090] In one or more embodiments, the fourth portion 412 of the rupture disc 41 includes a second annular groove 4121, and the projection of the second annular groove 4121 surrounds the projection of the third portion 411 along the axial direction Y of the cylindrical secondary battery. The portion inside the second annular groove 4121 in the fourth portion 412 and the third portion 411 form a flip body 413.

[0091] The flip body 413 flips relative to the connecting plate 42 when the air pressure in the housing 10 reaches a first threshold value, and the rupture disc 41 is configured to rupture the second annular groove 4121 to form an exhaust port when the air pressure in the housing 10 reaches a second threshold value, so that the gas in the housing 10 is discharged to the outside of the housing 10 through the exhaust port.

[0092] In one or more embodiments, the second annular groove 4121 is not a closed loop, so that after the second annular groove 4121 is ruptured, the flip body 413 is not easily separated from the fourth portion 412, thereby reducing the splashing of residues to the external environment when the cylindrical secondary battery 100 is depressurized.

[0093] In one or more embodiments, the second threshold value is P2, 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, 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 a range between any two of the above values. When the cylindrical secondary battery 100 is caused by external short circuit or high temperature environment, the pressure in the shell 10 rises to the range of P2, the second annular groove 4121 of the explosion-proof sheet 41 is broken to form an exhaust port, so as to facilitate the external exhaust of the high-pressure gas in the shell 10, reduce the probability of explosion or fire of the cylindrical secondary battery 100, and improve the safety of the secondary battery.

[0094] The material of the explosion-proof sheet 41 of the cylindrical secondary battery 100 is not particularly limited in the present application, and 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, and the heat generated during the operation of the cylindrical secondary battery 100 is easily reduced.

[0095] In one or more embodiments, the material of the explosion-proof sheet 41 is the same as that of the connecting plate 42, which is conducive to the welding of the explosion-proof sheet 41 and the connecting plate 42.

[0096] Similarly, the material of the explosion-proof sheet 41 is copper plated with nickel, which is conducive to improving the service life of the explosion-proof sheet 41 of the cylindrical secondary battery 100.

[0097] The copper in the above embodiments is pure copper, also known as red copper, and the copper content is above 99.5%. The nickel in the above embodiments is pure nickel, and the nickel content is above 99.5%. In one or more embodiments, the materials of the explosion-proof sheet 41 and the connecting plate 42 are both copper. The resistance of copper is small, which is conducive to reducing the resistance of the cylindrical secondary battery 100, and reducing the heat generated by the cylindrical secondary battery 100 during external output of current.

[0098] In one or more embodiments, the materials of the explosion-proof sheet 41 and the connecting plate 42 are both copper plated with nickel, which is conducive to welding, and also improves the rust resistance of the explosion-proof sheet 41 and the connecting plate 42 of the cylindrical secondary battery.

[0099] As the length of the cylindrical secondary battery 100 increases, the size increases, and the capacity can also increase accordingly. The inventor has noticed that, unlike a cylindrical secondary battery with a small capacity, in the event of a failure heat generation in a large-size cylindrical secondary battery, the heat generation is higher, and the internal temperature can also be relatively high.

[0100] As shown in FIG. 5, in one or more embodiments, the material of the first insulating piece 43 includes ceramic. After the air pressure inside the shell 10 reaches the first threshold, the rupture disc 41 flips over, and the connecting plate 42 breaks the electrical connection, due to the high melting point of the ceramic, which is not easy to melt, and is conducive to maintaining good insulation performance in a high-temperature environment inside the large-capacity cylindrical secondary battery 100, maintaining good insulation between the first portion 421 of the connecting plate 42 and the fourth portion 412 of the rupture disc 41, and reducing the probability that the first insulating piece 43 melts due to high temperature, causing the first portion 421 of the connecting plate 42 and the fourth portion 412 of the rupture disc 41 to be electrically connected, causing the current cutoff device 40 to fail to cut off the current.

[0101] In one or more embodiments, the ceramic includes oxide ceramic or non-oxide ceramic; the oxide ceramic includes at least one of Al2O3, ZrO, MgO, CaO, B2O3, ThO2, Cr2O3, SiO2, BeO, 3Al2O3·2SiO2; the non-oxide ceramic includes at least one of carbide ceramic, boride ceramic, nitride ceramic, or silicide ceramic. The above-mentioned materials have a high melting point and are not easy to melt, which is conducive to maintaining good insulation performance in a high-temperature environment inside the large-capacity cylindrical secondary battery 100.

[0102] The present application does not have a special limitation on the melting point of the first insulating piece 43, as long as the purpose of the present application is achieved. In one or more embodiments, the melting point of the first insulating piece 43 is t, 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 between any two of the above values. The first insulating piece 43 has a high melting point and is not easy to melt in a high-temperature environment, which is conducive to the first insulating piece 43 maintaining good insulation between the first portion 421 and the fourth portion 412, and reducing the risk of failure of the current cutoff device 40.

[0103] 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 between any two of them. The melting point of the first insulating member 43 is higher, which can withstand higher temperature and is not easy to melt in high temperature environment, which is conducive to the first insulating member 43 to maintain good insulation between the first part 421 and the fourth part 412, and reduce the risk of failure of the current cut-off device 40.

[0104] 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 between any two of them. The melting point of the first insulating member 43 is higher, which can withstand higher temperature and is not easy to melt in high temperature environment, which is conducive to the first insulating member 43 to maintain good insulation between the first part 421 and the fourth part 412, and reduce the risk of failure of the current cut-off device 40.

[0105] FIG. 10 is a structural schematic diagram of the first insulating member 43 of the cylindrical secondary battery 100 according to an embodiment of the present application, and FIG. 11 is a sectional structural schematic diagram of the first insulating member 43 of the cylindrical secondary battery 100 according to an embodiment of the present application. As shown in FIGS. 5, 10 and 11, 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 insulatingly connects the first part 421 of the connecting plate 42 and the fourth part 412 of the explosion-proof sheet 41, and along the radial direction X of the cylindrical secondary battery 100, the fifth part 431 insulatingly connects the top wall 11 and the explosion-proof sheet 41.

[0106] FIG. 12 is a structural schematic diagram of the support member of the cylindrical secondary battery according to an embodiment of the present application, and FIG. 13 is a sectional structural schematic diagram of the support member of the cylindrical secondary battery according to an embodiment of the present application. As shown in FIGS. 4, 12 and 13, in one or more embodiments, the cylindrical secondary battery 100 provided by the embodiments of the present application further includes: a support member 50; the shell 10 includes a top wall 11, and the first electrode terminal 30 and the top wall 11 are insulatingly connected; the support member 50 is arranged between the electrode assembly 20 and the top wall 11, and the support member 50 supports the electrode assembly 20, which is conducive to inhibiting the movement of the electrode assembly 20 and improving the service life of the cylindrical secondary battery 100.

[0107] The structure of the support 50 is not particularly limited in the present application, as long as the purpose of the present application is achieved. As shown in FIGS. 3, 4, 5, 12 and 13, in one or more embodiments, the support 50 comprises a first limiting portion 52; the top wall 11 comprises a second limiting portion 111, the first limiting portion 52 and the second limiting portion 111 cooperate to facilitate the relative limiting between the support 50 and the top wall 11, which is conducive to improving the position stability of the support 50 inside the cylindrical secondary battery 100.

[0108] In one or more embodiments, the first limiting portion 52 comprises a first protrusion 521, and the second limiting portion 111 comprises an annular groove 1111, which is configured to accommodate the first protrusion 521. The support 50 and the top wall 11 can be rotatably connected around the axis L0 of the cylindrical secondary battery 100. During the assembly of the support 50 and the top wall 11, the first protrusion 521 can be positioned at any position in the annular groove 1111, and the support 50 and the top wall 11 can be rotatably connected around the axis L0 of the cylindrical secondary battery 100. In this way, the support 50 and the top wall 11 can be assembled while achieving the limiting of both.

[0109] In one or more embodiments, the first limiting portion 52 comprises an annular groove 1111, and the second limiting portion 111 comprises a first protrusion 521.

[0110] In one or more embodiments, the first protrusion 521 is an annular protrusion, which is rotatably arranged in the annular groove 1111. During the assembly of the support 50 and the top wall 11, the annular protrusion is inserted into the annular groove 1111, and the support 50 and the top wall 11 are rotatably connected around the axis L0 of the cylindrical secondary battery 100. In this way, the support 50 and the top wall 11 can be further assembled.

[0111] FIG. 14 is a schematic structural diagram of a current collector disc of a cylindrical secondary battery according to an embodiment of the present application. As shown in FIGS. 4, 12, 13 and 14, in one or more embodiments, the cylindrical secondary battery 100 provided by the embodiments of the present application further comprises: a current collector disc 60, which is electrically connected to the electrode assembly 20, and part of the current collector disc 60 is arranged between the electrode assembly 20 and the support 50; the support 50 comprises a through hole 51, and part of the current interrupting device 40 is arranged in the through hole 51 and electrically connected to the current collector disc 60. The support 50 supports the current collector disc 60, which is conducive to improving the position stability of the current collector disc 60. Part of the current interrupting device 40 is arranged in the through hole 51 of the support 50, which is conducive to limiting the current interrupting device 40 in the radial direction X of the cylindrical secondary battery 100 by the support 50.

[0112] In one or more embodiments, the current collector plate 60 comprises a base 61 electrically connected to the electrode assembly 20 and a stack 62 electrically connected to the current interrupt device 40, so that the current collector plate 60 is electrically connected to the electrode assembly 20 and the current interrupt device 40.

[0113] In one or more embodiments, as shown in FIG. 3, FIG. 4, FIG. 5, FIG. 12 and FIG. 13, the support 50 comprises a first face 50a facing the electrode assembly 20, and the first face 50a is provided with a second protrusion 53, the second protrusion 53 is in contact with the current collector plate 60 to limit the position of the current collector plate 60 and improve the position stability of the current collector plate 60 inside the cylindrical secondary battery 100.

[0114] In one or more embodiments, the second protrusion 53 is at least two around the axis L0 of the cylindrical secondary battery 100, for example, the second protrusion 53 is two, and the two second protrusions 53 are arranged on both sides of the axis L0 of the cylindrical secondary battery 100, and the two second protrusions 53 are in contact with the base 61 of the current collector plate 60, respectively, to further improve the position stability of the current collector plate 60 inside the cylindrical secondary battery 100.

[0115] The structure of the second protrusion 53 is not particularly limited in the present application, and in one or more embodiments, the second protrusion 53 is a cylinder, a rectangular column or an arc column, etc.

[0116] In one or more embodiments, the second protrusion 53 is a solid structure to provide higher strength support for the current collector plate 60.

[0117] Unlike the solid structure of the second protrusion 53 in the above embodiments, in one or more embodiments, the support 50 comprises a second face 50b facing away from the electrode assembly 20, and the second face 50b is provided with a groove 54 extending into the second protrusion 53, and the groove 54 extends from the second face 50b into the second protrusion 53, which is beneficial to reduce the amount of material of the support 50, reduce the weight of the cylindrical secondary battery 100, and improve the mass energy density of the cylindrical secondary battery 100.

[0118] In one or more embodiments, the groove 54 is provided with a second through hole 55, and the second through hole 55 communicates the second face 50b of the support 50 and the first face 50a of the support 50. During use of the cylindrical secondary battery 100, if a small amount of electrolyte from the electrode assembly 20 position enters the groove 54 between the second face 50b of the support 50 and the top wall 11, the electrolyte entering the groove 54 can flow back to the electrode assembly 20 position through the second through hole 55, thereby reducing the probability of the electrolyte being stored in the groove 54 all the time and improving the utilization rate of the electrolyte.

[0119] In one or more embodiments, when the second protrusions 53 are at least two around the axis L0 of the cylindrical secondary battery 100, correspondingly, the grooves 54 are at least two around the axis L0 of the cylindrical secondary battery 100, each groove 54 is extended by the second surface 50b into the corresponding second protrusion 53.

[0120] In one or more embodiments, the at least two first protrusions 521 and the at least two grooves 54 are sequentially and alternately arranged around the axis L0 of the cylindrical secondary battery 100, and adjacent first protrusions 521 and grooves 54 are connected, so as to improve the space utilization of the support 50 (it is difficult to arrange the first protrusions 521 due to the part arranged with the grooves 54).

[0121] The material of the support 50 is not particularly limited in the present application, as long as the purpose of the application is achieved. In one or more embodiments, the material of the support 50 includes an insulating material, the support 50 is an insulating support, and the support 50 is arranged between the current collector plate 60 and the top wall 11, which is conducive to maintaining the insulation between the current collector plate 60 and the top wall 11.

[0122] In one or more embodiments, the material of the support 50 includes at least one of polyphthalamide, polyimide or polyether ether ketone, which has the advantages of high temperature resistance, corrosion resistance and high strength, and is conducive to improving the service life of the support 50.

[0123] In one or more embodiments, the electrode assembly 20 includes a winding type electrode assembly 20. In one or more embodiments, along the axial direction Y, the two ends of the electrode assembly 20 are respectively a first flattened portion (not shown in the figure) and a second flattened portion (not shown in the figure), and the cylindrical secondary battery 100 is a full tab battery.

[0124] In one or more embodiments, the cylindrical secondary battery 100 provided by the embodiments of the present application can be cycled for charging and discharging operation, so as to be used for multiple times. The present application does not have a particular limitation on the type of the cylindrical secondary battery 100, which can include any device that can generate an electrochemical reaction. In one or more embodiments, the cylindrical secondary battery 100 includes but is not limited to a lithium ion cylindrical secondary battery, so as to have a higher volumetric energy density, for example: the lithium ion cylindrical secondary battery includes but is not limited to a lithium cobaltate secondary battery, a ternary lithium secondary battery, a lithium iron phosphate secondary battery or a lithium manganate secondary battery, etc.

[0125] In the above embodiments, the cylindrical secondary battery 100 is a full tab battery, and the two ends of the electrode assembly 20 along the axial direction Y are formed into a first flattened portion (not shown in the figure) and a second flattened portion (not shown in the figure) by flattening, and the first flattened portion and the second flattened portion have different polarities.

[0126] In a second aspect, the application provides a battery pack 200, and FIG. 15 is a structural schematic diagram of the battery pack 200 according to an embodiment of the application. As shown in FIG. 15, the battery pack 200 includes the 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 are connected in series or in parallel, or a combination of series and parallel connection.

[0127] In a third aspect, the application provides a power consuming device 300, which includes the cylindrical secondary battery 100 or the battery pack 200 according to any of the above embodiments.

[0128] In one or more embodiments, FIG. 16 is a structural schematic diagram of a first power consuming device according to an embodiment of the application. As shown in FIG. 16, the power consuming device 300 includes the battery pack 200 according to the above embodiments, and the battery pack 200 includes the cylindrical secondary battery 100 according to the above embodiments.

[0129] In one or more embodiments, FIG. 17 is a structural schematic diagram of a second power consuming device according to an embodiment of the application. As shown in FIG. 17, the power consuming device 300 includes the cylindrical secondary battery 100 according to the above embodiments.

[0130] The power consuming device is not particularly limited in the application, and includes power consuming devices known in the prior art. For example, the power consuming device includes, but is not limited to, a computer, a smart phone, a backup power supply, a two-wheeled vehicle, a drone, a power tool, or an energy storage device, etc.

[0131] Embodiments

[0132] Preparation of the cylindrical secondary battery

[0133] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, with the separator between the positive electrode sheet and the negative electrode sheet to play a role of separation, and the electrode assembly is obtained by winding. The electrode assembly obtained by winding is placed in an aluminum-manganese alloy shell, and a current cutoff device and a first electrode terminal are assembled to form a cylindrical secondary battery. The positive electrode active material coated on the positive electrode sheet is NCM811, and the negative electrode active material coated on the negative electrode sheet is natural graphite. The positive electrode of the electrode assembly is electrically connected to the shell, and the negative electrode of the electrode assembly is electrically connected to the first electrode terminal. The material of the first insulating member is zirconia ceramic. The length diameter D of the cylindrical secondary battery is 35 mm, and the length L is 205 mm.

[0134] Comparative example

[0135] Except that the material of the first insulating member is polyethylene terephthalate (PET), the rest is the same as in the embodiment.

[0136] Short circuit test method:

[0137] A 5-megaohm resistor is connected between the top wall 11 and the first electrode terminal 30 of the cylindrical secondary battery to form an external short circuit, and a temperature indicator is attached to the top wall 11 and the first electrode terminal 30, respectively, to measure the temperature.

[0138] Short circuit test experiment:

[0139] The cylindrical secondary battery of the example and the cylindrical secondary batteries of the comparative examples are subjected to the above short circuit test method in turn.

[0140] After about 32 seconds, the current cutoff device 40 of the cylindrical secondary battery of the example is disconnected, and the cylindrical secondary battery does not catch fire or emit smoke. Through simulation experiments on the temperature of the top wall 11 and the first electrode terminal 30, it is found that the temperature at the current cutoff device 40 inside the cylindrical secondary battery is 281℃. When the cylindrical secondary battery is disassembled, it can be seen that the connecting plate 42 is pulled apart, and the first insulating member 43 between the outer periphery of the connecting plate 42 and the explosion-proof sheet 41 is in good shape.

[0141] After about 20 seconds, the cylindrical secondary battery of the comparative example emits smoke and catches fire. Through simulation experiments on the temperature of the top wall 11 and the first electrode terminal 30, it is found that the temperature at the current cutoff device 40 inside the cylindrical secondary battery is 278℃. When the cylindrical secondary battery is disassembled, it can be seen that the first insulating member 43 is melted, and the explosion-proof sheet 41 is lapped with the outer periphery of the connecting plate 42.

[0142] Short circuit test conclusion:

[0143] According to the above short circuit test results, the cylindrical secondary battery of the comparative example has the first insulating member 43 melted and the explosion-proof sheet 41 lapped with the outer periphery of the connecting plate 42 after about 20 seconds of short circuit test, and the current cutoff device 40 is ineffective. However, the cylindrical secondary battery of the example has the first insulating member 43 between the outer periphery of the connecting plate 42 and the explosion-proof sheet 41 in good shape, and the current cutoff device 40 remains effective after about 32 seconds of short circuit test.

[0144] The cylindrical secondary battery of the example of the present scheme has a lower risk of current cutoff device 40 failure.

[0145] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A cylindrical secondary battery characterized by comprising: Comprising: a housing; an electrode assembly disposed in the housing; a first electrode terminal insulatedly connected with the housing; a current interrupt device electrically connecting the electrode assembly and the first electrode terminal; the first electrode terminal is a negative electrode of the cylindrical secondary battery.

2. The cylindrical secondary battery according to claim 1, wherein the housing is a positive electrode of the cylindrical secondary battery.

3. The cylindrical secondary battery according to claim 1 or 2, wherein a material of the housing comprises aluminum or an aluminum alloy; and / or a material of the first electrode terminal comprises aluminum or an aluminum alloy.

4. The cylindrical secondary battery according to any one of claims 1 to 3, wherein the housing comprises a top wall, the first electrode terminal is insulatedly connected with the top wall; materials of the top wall and the first electrode terminal are both aluminum-manganese alloy.

5. The cylindrical secondary battery according to any one of claims 1 to 4, wherein the housing comprises a side wall, a material of the side wall is aluminum-manganese alloy.

6. The cylindrical secondary battery according to any one of claims 1 to 5, wherein the current interrupt device comprises a rupture disc and a connecting plate electrically connected with each other, the rupture disc is electrically connected with the first electrode terminal, and the connecting plate is electrically connected with the electrode assembly.

7. The cylindrical secondary battery according to claim 6, wherein a material of the connecting plate comprises one of steel, nickel, copper, copper-nickel plated nickel, or copper-nickel alloy; a material of the rupture disc comprises one of steel, nickel, copper, copper-nickel plated nickel, or copper-nickel alloy.

8. The cylindrical secondary battery according to claim 7, wherein the materials of the rupture disc and the connecting plate are both copper; or, the materials of the rupture disc and the connecting plate are both copper-nickel plated nickel.

9. The cylindrical secondary battery according to any one of claims 6 to 8, wherein the connecting plate comprises a first portion and a second portion connected with each other, the first portion surrounds the second portion, the first portion is connected with the electrode assembly, and the second portion is connected with the rupture disc; a thickness of the first portion is H1, a thickness of the second portion is H2, and 0.3≤H2 / H1≤0.

8.

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

11. The cylindrical secondary battery according to claim 9 or 10, wherein the rupture disc comprises a third portion and a fourth portion connected with each other, in an axial direction of the cylindrical secondary battery, a projection of the fourth portion surrounds a projection of the third portion, the third portion is connected with the second portion, and the fourth portion is connected with the first electrode terminal; a thickness of the third portion is H3, and 1.3≤H3 / H2≤3.

12. The cylindrical secondary battery according to any one of claims 9 to 11, wherein The connecting plate is welded with the anti-explosion sheet, the welding area is S, 0.8mm 2 ≤S≤4mm 2 .

13. The cylindrical secondary battery according to claim 11, wherein the cylindrical secondary battery comprises a first insulating member, at least a portion of the first insulating member is disposed between the first portion and the fourth portion; a thickness of the portion is H4, and 1.5≤H4 / H2≤5.

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

15. The cylindrical secondary battery according to claim 13 or 14, characterized by The material of the first insulating piece comprises ceramic.

16. The cylindrical secondary battery according to claim 15, characterized by The ceramic comprises oxide ceramic or non-oxide ceramic. The oxide ceramic comprises at least one of Al2O3, ZrO, MgO, CaO, B2O3, ThO2, Cr2O3, SiO2, BeO, 3Al2O3·2SiO2. The non-oxide ceramic comprises at least one of carbide ceramic, boride ceramic, nitride ceramic or silicide ceramic.

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

18. The cylindrical secondary battery according to claim 17, characterized by t≥500℃。 19. The cylindrical secondary battery according to claim 18, characterized by t≥800℃。 20. The cylindrical secondary battery according to any one of claims 1 to 19, characterized by, Further comprising: a support piece; The shell comprises a top wall, the first electrode terminal and the top wall are insulatedly connected; The support piece is arranged between the electrode assembly and the top wall.

21. The cylindrical secondary battery according to claim 20, characterized by Further comprising: a current collecting plate, the current collecting plate is electrically connected with the electrode assembly, part of the current collecting plate is arranged between the electrode assembly and the support piece; The support piece comprises a through hole, part of the current cut-off device is arranged in the through hole and is electrically connected with the current collecting plate.

22. The cylindrical battery according to any one of claims 1 to 21, wherein The current cut-off device is configured to be disconnected when the air pressure in the shell reaches a first threshold value, so as to disconnect the electrode assembly and the first electrode terminal.

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

24. A battery pack, characterized by The cylindrical secondary battery according to any one of claims 1 to 23.

25. An electrical device, comprising: The battery pack according to claim 24.

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