Secondary battery

Abstract

A secondary battery includes a cylindrical can having an open end and a closed end, an electrode assembly received in the can, and a cap assembly. The cap assembly includes an upper cap closing the open end of the can, a lower cap spaced apart from the upper cap and facing the electrode assembly, a vent plate disposed between the upper cap and the lower cap, a notch formed in the vent plate, and an insulating washer interposed between the vent plate and the can. A diameter of the lower cap is smaller than a diameter of the notch.

Description

Technical Field

[0001] Some aspects of this disclosure relate to secondary batteries. Background Technology

[0002] Unlike primary batteries, which are not designed for (re)charging, secondary (or rechargeable) batteries are designed to discharge and be recharged. Low-capacity secondary batteries are used in portable small electronic devices such as smartphones, feature phones, laptops, digital cameras, and camcorders, while high-capacity secondary batteries are widely used as power sources for motors in hybrid and electric vehicles, as well as for storing electricity (e.g., household and / or utility-scale power storage). A secondary battery typically comprises an electrode assembly containing positive and negative electrodes, a casing housing the electrode assembly, and electrode terminals connected to the electrode assembly.

[0003] The information disclosed in this section is provided only to enhance the understanding of the background of this disclosure, and therefore may contain information that does not constitute related (or prior art). Summary of the Invention

[0004] This disclosure relates to a secondary battery capable of discharging debris from the electrode assembly in response to an increase in internal pressure.

[0005] These and other aspects and features of this disclosure will be described in or will become apparent from the following description of embodiments of this disclosure.

[0006] A secondary battery according to an embodiment of the present disclosure includes a cylindrical can having an open end and a closed end, an electrode assembly housed in the can, and a cover assembly, the cover assembly including: an upper cover that closes the open end of the can; a lower cover that is spaced apart from the upper cover and faces the electrode assembly; a vent plate disposed between the upper cover and the lower cover, a notch formed in the vent plate; and an insulating gasket inserted between the vent plate and the can, wherein the outer diameter of the lower cover is smaller than the diameter of the notch.

[0007] The secondary battery may be further included as an insulator between the exhaust plate and the lower cover.

[0008] The outer diameter of the insulator is smaller than the diameter of the notch.

[0009] The exhaust plate can be placed around the edge of the top cover.

[0010] The top cover can be formed in the shape of a disc and can include a first region surrounded by an exhaust plate, a second region protruding in a direction away from the electrode assembly, and a third region connecting the first region to the second region, with a plurality of exhaust holes formed in the third region.

[0011] The exhaust plate can be formed in the shape of a disc and can include a first portion disposed below a second region of the top cover, an inclined surface extending upward from the first region, a second portion extending outward from the inclined surface and contacting the lower surface of the first region of the top cover, a third portion extending from the second portion and contacting the side surface of the first region of the top cover, and a fourth portion extending from the third portion and contacting the upper surface of the first region of the top cover.

[0012] A notch can be formed in the first part of the exhaust plate.

[0013] The exhaust plate may further include a contact portion that protrudes from the lower surface of the first portion toward the lower cover.

[0014] The notch can be spaced apart from the contact area.

[0015] The lower cover can be formed in the shape of a disc and can include a support portion disposed below the second region of the upper cover and the first part of the exhaust plate, and a connecting portion extending inward from the support portion and electrically connected to a contact portion of the exhaust plate.

[0016] The secondary battery may further include a first electrode terminal electrically connected to a first electrode plate of the electrode assembly and a closed end of the can, and a second electrode terminal electrically connected to the lower surface of the support portion and a second electrode plate of the electrode assembly.

[0017] A secondary battery according to another embodiment of the present disclosure includes a cylindrical can having an open end and a closed end, an electrode assembly housed in the can, and a cover assembly, the cover assembly including: a vent plate disposed at the open end of the can, a notch formed in the vent plate; a lower cover disposed between the vent plate and the electrode assembly and facing the electrode assembly; and an insulating gasket inserted between the vent plate and the can, wherein the outer diameter of the lower cover is smaller than the diameter of the notch.

[0018] The secondary battery may be further included as an insulator between the exhaust plate and the lower cover.

[0019] The outer diameter of the insulator is smaller than the diameter of the notch.

[0020] The exhaust plate can be disc-shaped and can have folded edges.

[0021] Insulating washers can be placed around the folded edges of the exhaust plate.

[0022] The exhaust plate may include a contact portion that protrudes from the lower surface of the exhaust plate and faces the lower cover.

[0023] The notch can be spaced apart from the contact area.

[0024] The lower cover may be disc-shaped and may include a support portion disposed below the exhaust plate and a connecting portion extending inward from the support portion and electrically connected to a contact portion of the exhaust plate.

[0025] The secondary battery may further include a first electrode terminal electrically connected to a first electrode plate of the electrode assembly and a closed end of the can, and a second electrode terminal electrically connected to the lower surface of the support portion and a second electrode plate of the electrode assembly. Attached Figure Description

[0026] The following figures illustrate embodiments of the present disclosure, and together with the detailed description of the present disclosure, aspects and features of the present disclosure are further described. This disclosure should not be construed as limited to the figures.

[0027] Figure 1 This is a perspective view showing a cylindrical secondary battery;

[0028] Figure 2 yes Figure 1 A cross-sectional view of the cylindrical secondary battery shown.

[0029] Figure 3 yes Figure 2 An enlarged cross-sectional view of the cover assembly shown;

[0030] Figure 4 This is a plan view of a secondary battery according to an embodiment of the present disclosure;

[0031] Figure 5 It is along Figure 4 A cross-sectional view of the secondary battery taken by line AA in the diagram;

[0032] Figure 6 yes Figure 5 An enlarged cross-sectional view of the cover assembly shown;

[0033] Figure 7 This is a plan view of a secondary battery according to another embodiment of the present disclosure;

[0034] Figure 8 It is along Figure 7 A cross-sectional view of the secondary battery taken by line CC in the diagram;

[0035] Figure 9 yes Figure 8 An enlarged cross-sectional view of the cover assembly shown;

[0036] Figure 10 and Figure 11 This is a perspective view showing a battery pack including an exemplary secondary battery according to the present disclosure;

[0037] Figure 12 It is a perspective view of a vehicle body including an exemplary battery pack according to this disclosure. Figure 13 It is a side view of a vehicle including an exemplary battery pack according to this disclosure. Detailed Implementation

[0038] In the following, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The terms or words used in this specification and claims are not to be construed as having a general or dictionary meaning, and should be interpreted in a way consistent with the technical concept of the present disclosure, based on the principle that the inventor can be his / her own lexicographer to appropriately define the concepts of the terms in order to best describe his / her invention.

[0039] The embodiments described in this specification and the configurations shown in the accompanying drawings are only some of the embodiments of this disclosure and do not represent all the technical spirit, aspects, and features of this disclosure. Therefore, it should be understood that various equivalents and modifications may exist to replace or modify the embodiments described herein at the time of filing this application.

[0040] It will also be understood that, when used in this specification, the terms “comprising,” “including,” “containing,” and / or “comprising” indicate the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0041] Furthermore, for ease of understanding of this disclosure, the drawings are not drawn to scale, and the dimensions of some components may be exaggerated. Additionally, in different embodiments, the same reference numerals may be assigned to the same components.

[0042] Referring to two compared elements, features, etc., as “identical” can mean that they are “substantially identical.” Therefore, the phrase “substantially identical” can include cases with deviations considered low in the art (e.g., 5% or less). Furthermore, when a parameter is said to be uniform in a given region, it can mean that it is uniform in terms of average value.

[0043] It will be understood that although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Therefore, the first element, component, region, layer, or section discussed below may be referred to as the second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0044] Throughout this specification, unless otherwise stated, each element may be singular or plural.

[0045] Arranging any element "above (or below)" or "above (below)" another element can mean that the arbitrary element can be positioned to contact the upper (or lower) surface of the other element, or that another element can be inserted between the other element and the arbitrary element positioned above (or below) the other element.

[0046] Furthermore, it will be understood that when a component is referred to as “linked,” “combined,” or “connected” to another component, these components can be directly “linked,” “combined,” or “connected” to each other, or another component can be “inserted” between these components.

[0047] Throughout this specification, when “A and / or B” is stated, it means A, B, or A and B, unless otherwise stated. That is, “and / or” includes any or all combinations of the listed items. When “C to D” is stated, it means C or more and D or fewer, unless otherwise stated.

[0048] The terminology used in this specification is for describing embodiments of this disclosure and is not intended to limit this disclosure.

[0049] The structure of a cylindrical secondary battery will now be described.

[0050] Figure 1 This is a perspective view showing a cylindrical secondary battery. Figure 2 yes Figure 1 The diagram shows a cross-sectional view of a cylindrical secondary battery. Figure 3 yes Figure 2 The enlarged cross-sectional view of the cover assembly is shown.

[0051] Reference Figures 1 to 3 The secondary battery 10 is a cylindrical battery. The secondary battery 10 includes a canister 100, an electrode assembly 300, and a cover assembly 500. The electrode assembly 300 is electrically connected to the canister 100 and the cover assembly 500 via a first electrode connector 410 and a second electrode connector 430, respectively. A first insulating plate 450 is disposed between the electrode assembly 300 and the canister 100. A second insulating plate 470 is disposed between the electrode assembly 300 and the cover assembly 500.

[0052] The tank 100 includes a disc-shaped bottom portion 110 and a cylindrical side portion 130 extending upward from the bottom portion 110. A beading portion 132 and a rolled edge portion 134 are provided at the upper end of the side portion 130. A cover assembly 500 is disposed between the beading portion 132 and the rolled edge portion 134. An electrode assembly 300 is housed in the tank 100 together with the electrolyte.

[0053] The electrode assembly 300 includes a first electrode plate 310 as a negative electrode plate, a second electrode plate 320 as a positive electrode plate, and a diaphragm 330. The electrode assembly 300 is configured such that the first electrode plate 310, the second electrode plate 320 and the diaphragm 330 are wound into a cylindrical shape, and the diaphragm 330 is inserted between the first electrode plate 310 and the second electrode plate 320.

[0054] The first insulating plate 450 is disc-shaped and made of insulating material. The first insulating plate 450 prevents the first electrode plate 310, which serves as the negative electrode plate, from being electrically connected to the bottom portion 110 of the can 100. The first electrode terminal piece 410 is welded to the bottom portion 110 and extends through the opening 454 in the first insulating plate 450.

[0055] The second insulating plate 470 is disc-shaped and made of insulating material. The second insulating plate 470 prevents the second electrode plate 320, which serves as the positive electrode plate, from being electrically connected to the cover assembly 500. The aforementioned second electrode terminal piece 430 is welded to the lower cover 550 and extends through the second insulating plate 470.

[0056] The cover assembly 500 includes an upper cover 510, a vent plate 530, a lower cover 550, an insulator 570, and an insulating washer 590. The cover assembly 500 is inserted between the annular rib portion 132 and the rolled edge portion 134 of the can 100 via the insulating washer 590.

[0057] The top cover 510 is exposed to the outside of the tank 100. The top cover 510 has a shape in which the central area convexly protrudes from the disc-shaped metal plate. Here, as... Figure 3 As shown, the edge region of the cover 510 will be referred to as the first region 512, the protruding region will be referred to as the second region 514, and the sloping region of the cover 510 between the first region 512 and the second region 514 will be referred to as the third region. A plurality of exhaust holes 516 forming a gas exhaust channel are provided in the third region.

[0058] The vent plate 530 has a generally disc-shaped form and is configured such that the edge of the vent plate 530 surrounds a first region 512 of the upper cover 510. The vent plate 530 includes a first portion 531, an inclined surface 532, a second portion 533, a third portion 534, a fourth portion 535, and a contact portion 536. A notch 537 is provided in the first portion 531. The notch 537 may be disposed adjacent to an air hole 555 in the lower cover 550. The second portion 533 contacts the lower surface of the first region 512 of the upper cover 510. The third portion 534 contacts the side surface of the first region 512. The fourth portion 535 contacts a portion of the upper surface of the first region 512 of the upper cover 510. The contact portion 536 protrudes from the center of the lower surface of the first portion 531 toward the lower cover 550 and is welded to the lower cover 550. The welded area is indicated by "W" in the drawings.

[0059] The notch 537 is configured to rupture in response to an increase in internal pressure of the secondary battery 10, thereby opening the vent plate 530. If the notch 537 ruptures, the first portion 531 breaks at the notch 537, causing the first portion 531 located inside the diameter of the notch 537 to move toward the upper cover 510. As a result, the contact portion 536 separates from the lower cover 550, thereby allowing gas from the electrode assembly 300 to be released.

[0060] The lower cover 550 has a basically disc shape and is in Figure 3 The lower cover 550 is positioned below the exhaust plate 530 in the shown shape. The lower cover 550 has a smaller diameter than the upper cover 510 or the exhaust plate 530, but a larger diameter than the recess 537. The lower cover 550 includes a first support portion 551, an inclined portion 552, a second support portion 553, and a connecting portion 554.

[0061] A first support portion 551 is disposed below the first portion 531 of the exhaust plate 530. An inclined portion 552 extends upward from the outer diameter portion of the first support portion 551. A second support portion 553 is disposed below and spaced apart from the second portion 533 of the exhaust plate 530. A connecting portion 554 extends from the inner diameter portion of the first support portion 551 toward the center of the lower cover 550. The connecting portion 554 is thinner than the other portions of the lower cover 550. The connecting portion 554 contacts and is welded to the contact portion 536. The connecting portion 554 also contacts and is welded to the second electrode terminal piece 430. The welding area is... Figure 3 The "W" indicates this. If the internal pressure of the secondary battery 10 increases due to the generation of internal gas, the connecting portion 554 of the lower cover 550 and the contact portion 536 of the vent plate 530 become convex towards the upper cover 510. If the welded areas separate from each other due to the deformation of the connecting portion 554 and the contact portion 536, the current path is interrupted. Subsequently, as the internal gas continues to accumulate, the aforementioned notch 537 ruptures, and the gas is released.

[0062] The insulator 570 is formed of an insulating material to maintain separation and electrical insulation between the second portion 533 of the exhaust plate 530 and the second support portion 553 of the lower cover 550. The insulator 570 is disposed between the second support portion 553 of the lower cover 550 and the second portion 533 of the exhaust plate 530.

[0063] An insulating gasket 590 surrounds the outer side of the vent plate 530. The top cover 510 and the vent plate 530 are joined to the tank 100 via the insulating gasket 590 to provide electrical insulation from the tank 100.

[0064] In the secondary battery 10 configuration described above, if the notch 537 ruptures due to increased internal pressure of the secondary battery 10, the first portion 531 located inside the diameter of the notch 537 completely separates from the remainder of the vent plate 530 and moves toward the upper cover 510. In another example, the connecting portion 554 disconnects from the first support portion 551 of the lower cover 550 and moves toward the upper cover 510 together with the separation area of ​​the vent plate 530 (i.e., the area located inside the diameter of the notch 537). Because the diameter of the lower cover 550 is larger than the diameter of the notch 537, only a portion of the lower cover 550 detaches with the separation area of ​​the vent plate 530, while the remainder of the lower cover 550 remains intact. Therefore, although the internal pressure of the secondary battery 10 increases, the opening created by the rupture of the lower cover 550 is small, and the lower cover 550 still blocks a portion of the opening of the can 100, preventing debris from the electrode assembly 300 damaged by fire or increased internal pressure from being discharged from the can 100.

[0065] In an environment using multiple secondary batteries (cells), if a fire occurs within one of the cells, it is necessary to prevent the fire from spreading to adjacent cells and to prevent thermal runaway. However, if debris from the electrode assembly is not discharged towards the cover assembly, the ring ribs or side sections of the can may be damaged. In such cases, the fire could spread to adjacent cells. Therefore, when the internal pressure of a cell increases due to a fire, etc., discharging electrode assembly debris to the outside of the cell via the rupture of the notch helps prevent the spread of the fire. To achieve this, the structure of the cover assembly needs to be improved.

[0066] In the following, a secondary battery according to an embodiment of the present disclosure that can solve the above-mentioned problems will be described in detail with reference to the accompanying drawings.

[0067] Figure 4 This is a plan view of a secondary battery according to an embodiment of the present disclosure. Figure 5 It is along Figure 4 The cross-sectional view of the secondary battery taken by line AA in the diagram. Figure 6 yes Figure 5 The enlarged cross-sectional view of the cover assembly is shown.

[0068] Reference Figures 4 to 6 The secondary battery 10a according to embodiments of the present disclosure may be a cylindrical battery. The secondary battery 10a may include a canister 100a, an electrode assembly 300a, and a cover assembly 500a. The electrode assembly 300a may be electrically connected to the canister 100a and the cover assembly 500a via a first electrode connector 410a and a second electrode connector 430a, respectively. A first insulating plate 450a may be disposed between the electrode assembly 300a and the canister 100a, and a second insulating plate 470a may be disposed between the electrode assembly 300a and the cover assembly 500a.

[0069] The can 100a may define the external shape of the secondary battery 10a and may be a cylindrical shape with one end open. The can 100a may include, or be referred to as, a shell, housing, or exterior component. The can 100a may be formed of a metal (such as steel, nickel-plated steel, steel alloy, aluminum, aluminum alloy, or deep-drawing cold-rolled steel (SPCE)) or of a laminated film or plastic constituting a bag. The can 100a may include a disc-shaped bottom portion 110a and a cylindrical side portion 130a extending upward from the bottom portion 110a. The side portion 130a may have an open upper end to which the cap assembly 500a is joined. A ring rib portion 132a and a rolled edge portion 134a may be provided at the upper end of the side portion 130a. Although this embodiment is described based on a configuration where the upper end of the can 100a is open, in other embodiments, the lower end of the can 100a may be open. The electrode assembly 300a can be contained together with the electrolyte in the tank 100a.

[0070] The rib portion 132a may be recessed inward at a position adjacent to the end of the side portion 130a. The rolled edge portion 134a may be spaced apart from the rib portion 132a and may be formed by bending the end of the side portion 130a inward. The cover assembly 500a may be disposed between the rib portion 132a and the rolled edge portion 134a. Therefore, the cover assembly 500a may be fixed in place by the rib portion 132a and the rolled edge portion 134a, so as not to separate from the can 100a.

[0071] Electrode assembly 300a may include, or be referred to as, an electrode group, an electrode body, or an electrode core. Electrode assembly 300a may include a first electrode plate 310a, a second electrode plate 320a, and a separator 330a. Electrode assembly 300a may be configured such that the first electrode plate 310a, the second electrode plate 320a, and the separator 330a are wound into a cylindrical shape, with the separator 330a interposed between the first electrode plate 310a and the second electrode plate 320a. In some examples, electrode assembly 300a may have a substantially open central region, which may be referred to as a core 380. A cylindrical central pin (optionally) may be inserted into the core 380 to provide structural support. The core 380 may also serve as a pathway for releasing internal pressure when the internal pressure of the secondary battery 10a exceeds a certain level. In some examples, as the internal pressure increases, internal gas may travel upward through the core 380 and may cause the notch 537a of the vent plate 530a to rupture. Therefore, the gas can be discharged through the top cover 510a, thereby reducing the internal pressure of the secondary battery 10a.

[0072] The first electrode plate 310a may be a negative electrode plate or a positive electrode plate. The first electrode plate 310a may include a first substrate which is a metal foil and a first active material layer provided on at least one surface of the first substrate. The first electrode plate 310a may include a first uncoated portion where the first active material is not applied. The first electrode tab 410a may be electrically connected to the first uncoated portion. In some examples, the first electrode plate 310a may serve as a negative electrode plate, the first active material may be a negative electrode active material, and the first electrode tab 410a may serve as a negative electrode tab. The first electrode tab 410a may include copper or nickel.

[0073] The negative electrode active material may include a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0074] The material capable of reversibly intercalating / deintercalating lithium ions may be a carbon-based negative electrode active material, which may include, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of crystalline carbon may include graphite, such as natural graphite or artificial graphite, and examples of amorphous carbon may include soft carbon, hard carbon, pitch carbide, mesophase pitch carbide, sintered coke, and the like.

[0075] A Si-based negative electrode active material or a Sn-based negative electrode active material may be used as the material capable of doping and dedoping lithium. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiO x (0<x<2), a Si-based alloy, or a combination thereof.

[0076] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to an embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surfaces of the silicon particles.

[0077] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core comprising crystalline carbon and silicon particles, and an amorphous carbon coating layer on the surface of the core.

[0078] A negative electrode for a lithium secondary battery may include a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector. The negative electrode active material layer may include a negative electrode active material, and may further include a negative electrode binder and / or a negative electrode conductive material.

[0079] For example, the negative electrode active material layer may include about 90 weight percent (wt%) to about 99.5 wt% of the negative electrode active material, about 0.5 wt% to about 5 wt% of the negative electrode binder, and about 0 wt% to about 5 wt% of the negative electrode conductive material.

[0080] Non-aqueous binders, aqueous binders, dry binders, or combinations thereof can be used as negative electrode binders. When using aqueous binders as negative electrode binders, cellulose compounds capable of imparting viscosity may be further included.

[0081] As the negative electrode current collector, one can be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with conductive metal, and combinations thereof.

[0082] Electrolytes used in lithium secondary batteries may include non-aqueous organic solvents and lithium salts.

[0083] Non-aqueous organic solvents act as a medium through which ions participating in the electrochemical reactions of the battery can move.

[0084] Non-aqueous organic solvents can be carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents, or combinations thereof, and can be used alone or in combination of two or more.

[0085] In addition, when using carbonate solvents, a mixture of cyclic carbonates and chain carbonates can be used.

[0086] Depending on the type of lithium secondary battery, the separator 330a may be present between the first electrode plate 310a (e.g., the negative electrode plate) and the second electrode plate 320a (e.g., the positive electrode plate). As the separator 330a, polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof can be used.

[0087] The second electrode plate 320a can be a negative electrode plate or a positive electrode plate. The second electrode plate 320a may include a second substrate as a metal foil and a second active material layer provided on at least one surface of the second substrate. The second electrode plate 320a may include a second uncoated portion to which the second active material is not applied. The second electrode tab 430a may be electrically connected to the second uncoated portion. In some examples, the second electrode plate 320a may be used as a positive electrode plate, the second active material may be a positive electrode active material, and the second electrode tab 430a may be used as a positive electrode tab. The second electrode tab 430a may include aluminum.

[0088] In some embodiments, compounds capable of reversibly inserting / deintercalating lithium (e.g., lithiation intercalation compounds) can be used as the positive electrode active material. For example, at least one of lithium and a composite oxide of a metal selected from cobalt, manganese, nickel, and combinations thereof can be used.

[0089] The composite oxide can be a lithium transition metal composite oxide, examples of which may include lithium nickel-based oxides, lithium cobalt-based oxides, lithium manganese-based oxides, lithium iron phosphate-based compounds, cobalt-free nickel-manganese-based oxides, or combinations thereof.

[0090] As an example, a compound represented by any of the following chemical formulas can be used: Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05), Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05), Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2), Li a Ni 1-b- c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2), Li a Ni b Co c L 1 d G e O2 (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1), Li a NiG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1), Li a CoG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1), Li a Mn 1-b G b O2 (0.90≤a≤1.8, 0.001≤b≤0.1), Li a Mn2G b O4 (0.90≤a≤1.8, 0.001≤b≤0.1), Li a Mn 1-g G g PO4 (0.90≤a≤1.8, 0≤g≤0.5), Li (3-f) Fe2(PO4)3 (0≤f≤2) and Lia FePO4 (0.90≤a≤1.8).

[0091] In the above chemical formulas: A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; L 1 It is Mn, Al, or a combination thereof.

[0092] The positive electrode for a lithium secondary battery may include a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector. The positive electrode active material layer may include a positive electrode active material and may further include a positive electrode binder and / or a positive electrode conductive material.

[0093] Based on a 100wt% positive electrode active material layer, the content of the positive electrode active material is in the range of about 90wt% to about 99.5wt%, and based on the 100wt% positive electrode active material layer, the content of each of the positive electrode binder and the positive electrode conductive material is in the range of about 0.5wt% to about 5wt%.

[0094] The positive electrode current collector can be aluminum (Al), but is not limited to this.

[0095] The diaphragm 330a can be inserted between the first electrode plate 310a and the second electrode plate 320a to prevent short circuit between the first electrode plate 310a and the second electrode plate 320a.

[0096] The diaphragm 330a may include a porous substrate and a coating layer on one or both surfaces of the porous substrate, comprising an organic material, an inorganic material, or a combination thereof.

[0097] Organic materials may include polyvinylidene fluoride polymers or (meth)acrylic acid polymers.

[0098] Inorganic materials may include, but are not limited to, inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite and combinations thereof.

[0099] Organic and inorganic materials can be mixed in a single coating layer, or they can be in the form of coating layers containing organic materials and coating layers containing inorganic materials stacked on top of each other.

[0100] Electrolyte solutions used in rechargeable lithium batteries may include non-aqueous organic solvents and lithium salts.

[0101] Non-aqueous organic solvents can be used as media for transporting ions that participate in the electrochemical reactions of a battery. Non-aqueous organic solvents can be carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents, or combinations thereof, and can be used alone or in combination of two or more.

[0102] In addition, when using carbonate solvents, cyclic carbonates and chain carbonates can be used in combination.

[0103] The first insulating plate 450a may have a plate shape and may be made of an insulating material. The first insulating plate 450a prevents the first electrode plate 310a, which serves as the negative electrode plate, from being electrically connected to the bottom portion 110a of the tank 100a. For example, the first insulating plate 450a prevents direct contact between the first electrode plate 310a and the bottom portion 110a. The first insulating plate 450a may include a first hole 452a communicating with the core 380. A plurality of second holes 454a may also be formed through the first insulating plate 450a. When a large amount of gas is generated due to an abnormal condition of the secondary battery 10a, the first hole 452a and the second holes 454a may allow the gas to move toward the cover assembly 500a. The second holes 454a may also serve as flow paths for gas and electrolyte. The first electrode tab 410a may extend through the second hole 454a and may be welded to the bottom portion 110a. In some embodiments, the first insulating plate 450a may be replaced by an insulating tape or insulating sheet.

[0104] The second insulating plate 470a prevents the second electrode plate 320a, which serves as the positive electrode plate, from being electrically connected to the cover assembly 500a. For example, the second insulating plate 470a prevents direct contact between the second electrode plate 320a and the cover assembly 500a. One or more holes may be formed in the second insulating plate 470a. The second electrode tab 430a may extend through one of the holes and be electrically connected to the lower cover 550a. Some of the holes may serve as flow paths through which electrolyte is injected into the electrode assembly 300a during battery manufacturing.

[0105] Although not shown in the accompanying drawings, other current-collecting structures can be applied to the secondary battery 10a of this embodiment. For example, the first uncoated portion and the second uncoated portion described above can be notched into a predetermined shape to serve as a first base terminal and a second base terminal, respectively. The first base terminal and the second base terminal can be electrically connected to a first current collector and a second current collector, respectively. The first current collector can be electrically connected to the canister 100a. The second current collector can be electrically connected to the cover assembly 500a while being electrically insulated from the canister 100a.

[0106] The lid assembly 500a can be coupled to the open end of the can 100a. The lid assembly 500a may include an upper lid 510a, a vent plate 530a, a lower lid 550a, an insulator 570a, and an insulating gasket 590a. The lid assembly 500a can be inserted between the annular rib portion 132a and the rolled edge portion 134a of the can 100a via the insulating gasket 590a. The upper lid 510a, vent plate 530a, and lower lid 550a may be formed of aluminum, aluminum alloy, nickel-plated steel, steel alloy, or equivalents thereof. However, this disclosure is not limited to these examples.

[0107] The top cover 510a can be positioned at the outermost part of the cover assembly 500a (based on...) Figure 5 The top part of the cover 510a is located at the uppermost part of the cover 510a and can be exposed to the outside of the tank 100a. The cover 510a may have a shape in which a portion protrudes convexly from the disc-shaped metal plate. The protruding portion of the cover 510a may correspond to the central area of ​​the disc-shaped metal plate. The exhaust plate 530a may be disposed below the cover 510a and around the edge of the cover 510a. Here, as... Figure 6 As shown, the edge region of the upper cover 510a will be referred to as the first region 512a, the protruding portion of the upper cover 510a will be referred to as the second region 514a, and the inclined region between the first region 512a and the second region 514a will be referred to as the third region. Multiple discharge holes 516a may be formed in the third region. The discharge holes 516a can serve as passageways through which gas passing through the core 380 is discharged.

[0108] The exhaust plate 530a may have a generally disc-shaped form and may be formed such that the edge of the exhaust plate 530a surrounds a first region 512a of the cover 510a. More specifically, the edge of the exhaust plate 530a may surround a portion of the upper surface, side surface, and lower surface of the first region 512a. The exhaust plate 530a may have a larger diameter than the cover 510a. The exhaust plate 530a may include a first portion 531a, an inclined surface 532a, a second portion 533a, a third portion 534a, a fourth portion 535a, and a contact portion 536a. A notch 537a may be provided in the first portion 531a.

[0109] Here, the portion of the exhaust plate 530a located below the second region 514a of the upper cover 510a is referred to as the first portion 531a. Based on Figure 6 An inclined surface 532a extends upward from the outer diameter portion of the first portion 531a, and a second portion 533a extends outward from the inclined surface 532a. The second portion 533a can contact the lower surface of the first region 512a of the upper cover 510a. Thus, the inclined surface 532a obliquely connects the first portion 531a and the second portion 533a to each other, resulting in a height difference between the first portion 531a and the second portion 533a. Figure 6As shown, the first portion 531a can be located at a lower position than the second portion 533a and can be closer to the lower cover 550a. That is, the second portion 533a can be located at a higher position than the first portion 531a, and the inclined surface 532a is based on... Figure 6 The orientation shown is upwardly inclined. The third portion 534a can be bent substantially vertically from the second portion 533a and can extend upward. The third portion 534a can contact the side surface of the first region 512a of the upper cover 510a. The fourth portion 535a can be bent substantially vertically from the third portion 534a and can extend toward the center of the upper cover 510a. The fourth portion 535a can contact a portion of the upper surface of the first region 512a of the upper cover 510a. The contact portion 536a can be a region of predetermined area protruding from the center of the lower surface of the first portion 531a toward the lower cover 550a. The thickness of the portion of the exhaust plate 530a in the contact portion 536a can be equal to or greater than the thickness of the other portions of the exhaust plate 530a. The contact portion 536a can directly contact and be welded to the lower cover 550a. Except for the contact portion 536a, the other portions of the exhaust plate 530a may not contact the lower cover 550a. For example, because the contact portion 536a protrudes, the first portion 531a, the inclined surface 532a, and the second portion 533a can be spaced apart from the lower cover 550a. In some embodiments, the insulator 570a can be inserted between the exhaust plate 530a and the lower cover 550a. The first portion 531a, the inclined surface 532a, the second portion 533a, the third portion 534a, the fourth portion 535a, and the contact portion 536a can be integrally formed.

[0110] At least one notch 537a may be provided in the first portion 531a of the vent plate 530a. The notch 537a may be spaced apart from the contact portion 536a. In some examples, the notch 537a may be provided in the surface of the first portion 531a facing the upper cover 510a. In other examples, the notch 537a may be provided in the surface of the first portion 531a facing the lower cover 550a. If the outer diameter of the secondary battery 10a (outer diameter of the can 100a) is 21 mm, the diameter D1 of the notch 537a may be 8 mm or greater. In another example, if the outer diameter of the secondary battery 10a is 18 mm, the diameter D1 of the notch 537a may be 7 mm or greater. The notch 537a may be configured to rupture in response to an increase in the internal pressure of the secondary battery 10a, thereby opening the vent plate 530a. The opening of the exhaust plate 530a refers to the state in which the portion inside the diameter D1 of the notch 537a separates from the other parts of the exhaust plate 530a due to the breakage of the notch 537a. When the notch 537a breaks, the lower cover 550a can move toward the upper cover 510a. As a result, the notch 537a can provide a current interruption function caused by pressure (e.g., the internal pressure of the secondary battery 10a).

[0111] The lower cover 550a can be substantially disc-shaped and can have a smaller diameter (i.e., outer diameter) than the notch 537a. For example... Figure 6 As shown, the lower cover 550a can be disposed below the exhaust plate 530a. The lower cover 550a can be the innermost component of the cover assembly 500a, closest to the electrode assembly 300a. The lower cover 550a can support the upper cover 510a and the exhaust plate 530a to prevent the upper cover 510a from deforming due to external forces. The lower cover 550a may include a first support portion 551a and a connecting portion 552a.

[0112] The first support portion 551a can be disposed below the second region 514a of the upper cover 510a and the first portion 531a of the exhaust plate 530a, with the first support portion 551a spaced apart from the first portion 531a of the exhaust plate 530a. The second electrode terminal piece 430a can be electrically connected to the lower surface of the first support portion 551a. The connection can be made using ultrasonic welding or laser welding. The connecting portion 552a can extend inwardly from the first support portion 551a.

[0113] The connecting portion 552a can extend from the inner diameter portion of the first support portion 551a toward the center of the lower cover 550a. The connecting portion 552a can have a smaller thickness than the first support portion 551a (e.g., Figure 6(Thickness in the vertical direction shown). Because the thickness of the connecting portion 552a is less than the thickness of the first support portion 551a, the lower surface of the connecting portion 552a can be connected to the lower surface of the first support portion 551a in a stepped manner. Therefore, the lower surface of the connecting portion 552a can be closer to the contact portion 536a of the exhaust plate 530a than the lower surface of the first support portion 551a.

[0114] As described above, the outer diameter D2 of the lower cover 550a can be smaller than the diameter D1 of the notch 537a. The minimum outer diameter of the lower cover 550a required to reliably support the upper cover 510a and the vent plate 530a and stabilize variations can be 6 mm. For example, if the outer diameter of the secondary battery 10a is 21 mm, the outer diameter D2 of the lower cover 550a can be greater than or equal to 6 mm and less than 8 mm. In some examples where the outer diameter of the secondary battery 10a is 18 mm, the outer diameter D2 of the lower cover 550a can be greater than or equal to 6 mm and less than 7 mm.

[0115] The insulator 570a can be formed of an insulating material to maintain separation and electrical insulation between the exhaust plate 530a and the lower cover 550a. The insulator 570a can be disposed between the first support portion 551a of the lower cover 550a and the first portion 531a of the exhaust plate 530a. In this configuration, the insulator 570a can be disposed inside the recess 537a. The insulator 570a can be formed into an annular shape with a predetermined width. Figure 6 In the example shown, the lateral width of the insulator 570a is smaller than the lateral width of the first support portion 551a. In other embodiments, the insulator 570a may be... Figure 6 The cross-section shown has various cross-sectional shapes, such as L-shaped or U-shaped. The insulator 570a can have an outer diameter that does not affect the breakage of the notch 537a. For example, the outer diameter of the insulator 570a can be greater than or equal to 4.5 mm and less than the diameter D1 of the notch 537a. The insulator 570a can be formed of, for example, polyethylene (PE), polypropylene (PP), polystyrene (PS), ethylene-vinyl acetate copolymer (EVA), or equivalents thereof. However, this disclosure is not limited to these examples. The insulator 570a can be joined to the exhaust plate 530a and the lower cover 550a by ultrasonic welding, laser welding, thermoforming, etc.

[0116] Reference Figure 6 The insulating gasket 590a can be installed around the outside of the vent plate 530a while the cover 510a and the vent plate 530a are joined together. The cover 510a and the vent plate 530a can be joined to the tank 100a via the insulating gasket 590a to provide electrical insulation from the tank 100a. The insulating gasket 590a can be made of the same or similar material as the insulator 570a.

[0117] As described above, because the outer diameters of the lower cover 550a and the insulator 570a are smaller than the diameter D1 of the recess 537a, the lower cover 550a and the insulator 570a do not affect the breakage and operating area of ​​the recess 537a. Furthermore, because the outer diameters of the lower cover 550a and the insulator 570a are smaller than the diameter D1 of the recess 537a, when the recess 537a breaks, the lower cover 550a and the insulator 570a can be together with the area of ​​the upper cover 510a inside the recess 537a in the breakage. Figure 6 The arrows indicate the direction of discharge. These discharge areas are defined by... Figure 6 The dashed line B indicates that the area indicated by dashed line B can be fully opened when the notch 537a ruptures due to increased internal pressure of the secondary battery 10a. Figures 1 to 3 Compared to the embodiment shown where a portion of the lower cover 550 remains in place, the size of the opening can be increased. As a result of the increased opening size, debris from the electrode assembly 300a can be discharged through the opening while being pushed upwards by internal pressure. As debris from the electrode assembly 300a is pushed upwards by internal pressure... Figure 6 Discharge is directed in the direction indicated by the arrow, and the top cover 510a can also be pushed and opened. If the internal pressure increases due to fire, etc., debris from the electrode assembly 300a can be directed towards the top cover 510a (based on...). Figure 5 The fire can be discharged upwards, and flames or sparks can also be discharged upwards. Furthermore, the rapid discharge of debris and gas release from the electrode assembly 300a prevents the ribbed portion 132a or side portion 130a of the tank 100a from rupturing. Therefore, the fire can be prevented from spreading to adjacent secondary batteries.

[0118] Figure 7 This is a plan view of a secondary battery according to another embodiment of the present disclosure. Figure 8 It is along Figure 7 The cross-sectional view of the secondary battery taken from line CC. Figure 9 yes Figure 8 The enlarged cross-sectional view of the cover assembly is shown.

[0119] Reference Figures 7 to 9According to another embodiment of this disclosure, the secondary battery 10b can be a cylindrical battery. The secondary battery 10b may include a canister 100b, an electrode assembly 300b, and a cover assembly 500b. The canister 100b may include a bottom portion 110b and a side portion 130b. The electrode assembly 300b may include a first electrode plate 310b, a second electrode plate 320b, and a separator 330b. The electrode assembly 300b may be electrically connected to the canister 100b and the cover assembly 500b via a first electrode connector 410b and a second electrode connector 430b, respectively. A first insulating plate 450b may be disposed between the electrode assembly 300b and the canister 100b. A second insulating plate 470b may be disposed between the electrode assembly 300b and the cover assembly 500b. Because the configuration of the secondary battery 10b, except for the cover assembly 500b, is the same as in the above embodiment, its detailed description will be omitted.

[0120] The cover assembly 500b may include an exhaust plate 530b, a lower cover 550b, an insulator 570b, and an insulating gasket 590b.

[0121] The exhaust plate 530b may have a substantially disc shape and may be made of the same material as the exhaust plate 530a described above. The exhaust plate 530b may be formed into a disc shape with folded edges. The exhaust plate 530b may include a first portion 531b, a second portion 532b, a third portion 533b, a fourth portion 534b, and a fifth portion 535b. The first portion 531b to the fifth portion 535b may be integrally formed.

[0122] The first portion 531b may correspond to the central region of the disc-shaped structure. The upper surface of the first portion 531b may be flat, and the lower surface of the first portion 531b may protrude toward the electrode assembly 300b. The protruding lower surface may contact and be electrically connected to the lower cover 550b. This connection can be made by ultrasonic welding or laser welding. In other embodiments, the lower surface of the first portion 531b may have a flat shape rather than a protruding shape. That is, the protruding shape of the lower surface of the first portion 531b is optional.

[0123] The second portion 532b may extend outward from the outer diameter portion of the first portion 531b. The second portion 532b may have an area less than or equal to the area of ​​the first portion 531b, and a thickness less than or equal to the thickness of the first portion 531b. For example... Figure 9As shown, the second portion 532b can be positioned higher than the first portion 531b. Therefore, the second portion 532b can extend from the first portion 531b in a stepped manner. However, the stepped structure between the first portion 531b and the second portion 532b is optional. In other embodiments, the first portion 531b and the second portion 532b can be formed in the same plane without a step between them.

[0124] A notch 537b may be provided in the surface of the electrode assembly 300b facing the second portion 532b. The notch 537b may have the same diameter as the notch 537a in the above embodiment. For example, if the outer diameter of the secondary battery 10b (outer diameter of the can 100b) is 21 mm, the diameter D3 of the notch 537b may be 8 mm or greater. In another example, if the outer diameter of the secondary battery 10b is 18 mm, the diameter D3 of the notch 537b may be 7 mm or greater.

[0125] The third part 533b may extend outward from the outer diameter portion of the second part 532b. The upper surface of the third part 533b may be inclined upward, and the lower surface of the third part 533b may be aligned with the lower surface of the second part 532b. The third part 533b may be used to connect the second part 532b to the fourth part 534b. The third part 533b may have a thickness equal to or greater than the thickness of the second part 532b.

[0126] The fourth portion 534b may extend outward from the outer diameter portion of the third portion 533b and be surrounded by the insulating washer 590b. The fifth portion 535b may contact the upper or lower surface of the fourth portion 534b. In some examples, the fifth portion 535b may be folded upward or downward. Furthermore, the fourth portion 534b may have a greater thickness than the third portion 533b.

[0127] The fifth part 535b can extend outward from the outer diameter portion of the fourth part 534b and can be folded such that the lower surface of the fifth part 535b contacts the upper surface of the fourth part 534b (e.g., Figure 9 (As shown) or such that the upper surface of the fifth portion 535b contacts the lower surface of the fourth portion 534b. The fifth portion 535b and the fourth portion 534b may be surrounded by an insulating washer 590b. In some examples, the fifth portion 535b may have the same thickness as the fourth portion 534b.

[0128] Here, the exhaust plate 530b has been described as including a first portion 531b through a fifth portion 535b, but the shape of the exhaust plate 530b is not limited thereto. In one example, the exhaust plate 530b may include a first portion connected to the lower cover 550b, a second portion including a notch 537b and surrounded by an insulating washer 590b, and a third portion folded to fit tightly into the second portion.

[0129] The lower cover 550b can have a substantially disc shape and can have a smaller diameter than the notch 537b, as shown in the image. Figure 9 The lower cover 550b is positioned below the exhaust plate 530b. The lower cover 550b may be the innermost component of the cover assembly 500b, closest to the electrode assembly 300b. The lower cover 550b can support the exhaust plate 530b to prevent deformation due to external forces. The lower cover 550b may include a first support portion 551b and a connecting portion 552b.

[0130] The first support portion 551b can be disposed below the boundary region between the first portion 531b and the second portion 532b of the exhaust plate 530b. The first support portion 551b can be spaced apart from the first portion 531b and the second portion 532b of the exhaust plate 530b. The edge of the first support portion 551b can be closer to the electrode assembly 300b than other areas of the first support portion 551b. The edge of the first support portion 551b can be stepped relative to other areas of the first support portion 551b. The upper surface 5510b of the first support portion 551b can be spaced apart from the lower surface of the insulator 570b. A hole for gas release can be formed through the first support portion 551b. The second electrode terminal 430b can be electrically connected to the lower surface of the first support portion 551b. The connection can be made by ultrasonic welding or laser welding. The connecting portion 552b can extend inward from the first support portion 551b.

[0131] The connecting portion 552b can extend from the inner diameter portion of the first support portion 551b toward the center of the lower cover 550b. The connecting portion 552b can have a smaller thickness than the first support portion 551b. Figure 9 (Thickness in the vertical direction shown). Because the thickness of the connecting portion 552b is less than the thickness of the first support portion 551b, the lower surface of the connecting portion 552b can be connected to the lower surface of the first support portion 551b in a stepped manner. Compared to the lower surface of the first support portion 551b reaching the exhaust plate 530b, the lower surface of the connecting portion 552b can be closer to the contact portion 536b of the exhaust plate 530b.

[0132] As described above, the outer diameter D4 of the lower cover 550b can be smaller than the diameter D3 of the recess 537b. The minimum outer diameter of the lower cover 550b required to reliably support the vent plate 530b and stabilize its changes can be, for example, 6 mm. Furthermore, if the outer diameter of the exemplary secondary battery 10b described above is 21 mm, then the outer diameter D4 of the lower cover 550b can be, for example, greater than or equal to 6 mm and less than 8 mm. If the outer diameter of the secondary battery 10b is 18 mm, then the outer diameter D4 of the lower cover 550b can be, for example, greater than or equal to 6 mm and less than 7 mm.

[0133] The insulator 570b can be formed of the same material as the insulator 570a in the above embodiment and can perform the same function as the insulator 570a. The insulator 570b can be disposed between the first support portion 551b of the lower cover 550b and the first portion 531b of the vent plate 530b. In this configuration, the insulator 570b can be disposed inside the recess 537b. The insulator 570b can be formed into an annular shape with a predetermined width. For example, as... Figure 9 As shown, the lateral width of the insulator 570b can be smaller than the lateral width of the first support portion 551b. In other embodiments, the insulator 570b can be... Figure 9 The cross-section shown has various cross-sectional shapes, such as " "L-shaped" or " The insulator 570b may have an outer diameter that does not affect the breakage of the notch 537b. For example, the outer diameter of the insulator 570b may be greater than or equal to 4.5 mm and less than the diameter D3 of the notch 537b.

[0134] The insulating gasket 590b can be installed around the outside of the vent plate 530b. Furthermore, the vent plate 530b can be bonded to the tank 100b via the insulating gasket 590b to provide electrical insulation from the tank 100b. The insulating gasket 590b can be made of the same or similar material as the insulator 570b.

[0135] According to Figures 7 to 9 In the secondary battery 10b of the illustrated embodiment, because the outer diameters of the lower cover 550b and the insulator 570b are smaller than the diameter D3 of the notch 537b, when the notch 537b breaks, the lower cover 550b and the insulator 570b can break together with the area inside the notch 537b. Figure 9 Discharge is indicated by the arrow in the diagram. When notch 537b ruptures due to increased internal pressure of the secondary battery 10b, the area indicated by the dashed line D can be fully opened. Therefore, debris from the electrode assembly 300b can also be discharged in the direction indicated by the arrow. Figure 9The discharge is directed in the direction indicated by the arrow. Discharge of debris from electrode assembly 300b prevents rupture of the annular rib portion 132b or side portion 130b of tank 100b. Therefore, it prevents the fire from spreading to adjacent secondary batteries.

[0136] The secondary batteries 10a and 10b according to the above embodiments can be used to manufacture battery packs.

[0137] Figure 10 and Figure 11 This is a perspective view showing a battery pack 3000 including an exemplary secondary battery.

[0138] Reference Figure 10 and Figure 11 The battery pack 3000 may include a plurality of battery modules 2000 and a housing 3100 for accommodating the plurality of battery modules 2000. For example, the housing 3100 may include a battery pack cover 3110 and a pack frame 3120 joined together to define a space for accommodating the plurality of battery modules 2000. The plurality of battery modules 2000 may be electrically connected to each other using busbars 2510, and the plurality of battery modules 2000 may be electrically connected to each other in series / parallel or a series-parallel hybrid method to obtain a desired (e.g., required) electrical output. In the figures, for convenience, components such as busbars for electrical connections to individual battery cells, cooling units, and external terminals are omitted. In some examples, the battery pack 3000 may be installed in a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle may include a four-wheeled vehicle or a two-wheeled vehicle.

[0139] Figure 12 It is a perspective view of a vehicle body 4000 including an exemplary battery pack 3000 according to this disclosure. Figure 13 This is a side view of a vehicle 5000 including an exemplary battery pack 3000 according to this disclosure. Figure 12 In this design, the housing 3100 of the battery pack 3000 may include a battery pack cover 3110 and a battery pack frame 3120. The battery pack cover 3110 is part of the vehicle bottom 4100 and may correspond to a first housing, while the battery pack frame 3120 is disposed below the vehicle bottom 4100 and may correspond to a second housing. The battery pack cover 3110 and the battery pack frame 3120 may be integrally formed with the vehicle floor 4200. The vehicle bottom 4100 separates the interior and exterior of the vehicle, and the battery pack frame 3120 may be disposed on the exterior of the vehicle.

[0140] exist Figure 13In this embodiment, vehicle 5000 can be formed by combining an engine hood 5100 at the front of vehicle 5000 and additional portions of fenders 5200 located at the front and rear of vehicle 5000, respectively, to vehicle body 4000. Vehicle 5000 may include battery pack 3000, the housing 3100 of battery pack 3000 including battery pack cover 3110 and battery pack frame 3120, and battery pack 3000 can be integrated into vehicle body 4000.

[0141] According to embodiments of this disclosure, because the diameter (outer diameter) of the lower cover is smaller than the diameter of the recess in the vent plate, the lower cover can discharge from the secondary battery in response to the rupture of the vent plate (a portion of the vent plate separates from the rest) caused by an increase in the internal pressure of the secondary battery. Therefore, when the lower cover is discharged from the secondary battery along with the separated area of ​​the vent plate, debris from the electrode assembly can also be discharged from the secondary battery. Furthermore, due to the above structure and configuration, a discharge path to the upper terminal portion of the secondary battery, rather than other portions, can be ensured, and the spread of fire to adjacent secondary batteries can be prevented.

[0142] However, the aspects and features of this disclosure are not limited to those described above, and those skilled in the art will clearly understand from the detailed description below that other aspects and features not mentioned will be apparent.

[0143] Although this disclosure has been described above with reference to only a limited number of embodiments and accompanying drawings, this disclosure is not limited to the disclosed embodiments. Various changes and modifications can be made by those skilled in the art within the spirit and scope of this disclosure.

[0144] This application claims priority and benefit to Korean Patent Application No. 10-2025-0046194, filed on April 9, 2025, with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference.

Claims

1. A secondary battery, comprising: A cylindrical can with an open end and a closed end; The electrode assembly is housed in the can; as well as Cover components, including: The top cover closes the open end of the can. The lower cover is spaced apart from the upper cover and faces the electrode assembly. An exhaust plate is disposed between the upper cover and the lower cover, and a notch is formed in the exhaust plate. An insulating washer is inserted between the exhaust plate and the tank. The outer diameter of the lower cover is smaller than the diameter of the recess.

2. The secondary battery according to claim 1, further comprising an insulator between the vent plate and the lower cover.

3. The secondary battery according to claim 2, wherein, The outer diameter of the insulator is smaller than the diameter of the notch.

4. The secondary battery according to claim 1, wherein, The exhaust plate surrounds the edge of the upper cover.

5. The secondary battery according to claim 4, wherein, The upper cover is formed in the shape of a disk and includes: The first region is surrounded by the exhaust plate; The second region protrudes in a direction away from the electrode assembly; and A third region connects the first region to the second region, and a plurality of discharge holes are formed in the third region.

6. The secondary battery according to claim 5, wherein, The exhaust plate is formed in a disc shape and includes: The first part is disposed below the second region of the upper cover; An inclined surface extending upward from the first region; The second part extends outward from the inclined surface and contacts the lower surface of the first region of the upper cover; The third portion extends from the second portion and contacts the side surface of the first region of the upper cover; and The fourth part extends from the third part and contacts the upper surface of the first region of the top cover.

7. The secondary battery according to claim 6, wherein, The notch is formed in the first portion of the exhaust plate.

8. The secondary battery according to claim 7, wherein, The exhaust plate further includes a contact portion that protrudes from the lower surface of the first portion toward the lower cover.

9. The secondary battery according to claim 8, wherein, The notch is spaced apart from the contact portion.

10. The secondary battery according to claim 9, wherein, The lower cover is formed in the shape of a disk and includes: A support portion is disposed below the second region of the upper cover and the first portion of the exhaust plate; and The connecting portion extends inward from the supporting portion and is electrically connected to the contact portion of the exhaust plate.

11. The secondary battery according to claim 10, further comprising: The first electrode terminal is electrically connected to the first electrode plate of the electrode assembly and the closed end of the can; as well as The second electrode terminal is electrically connected to the lower surface of the support portion and the second electrode plate of the electrode assembly.

12. A secondary battery, comprising: A cylindrical can with an open end and a closed end; The electrode assembly is housed in the can; as well as Cover components, including: An exhaust plate is disposed at the open end of the can, and a notch is formed in the exhaust plate. The lower cover is disposed between the exhaust plate and the electrode assembly and faces the electrode assembly. An insulating gasket is placed between the exhaust plate and the tank. The outer diameter of the lower cover is smaller than the diameter of the recess.

13. The secondary battery according to claim 12, further comprising an insulator between the vent plate and the lower cover.

14. The secondary battery according to claim 13, wherein, The outer diameter of the insulator is smaller than the diameter of the notch.

15. The secondary battery according to claim 12, wherein, The exhaust plate is disc-shaped and has folded edges.

16. The secondary battery according to claim 15, wherein, The insulating gasket surrounds the folded edge of the exhaust plate.

17. The secondary battery according to claim 12, wherein, The exhaust plate includes a contact portion that protrudes from the lower surface of the exhaust plate and faces the lower cover.

18. The secondary battery according to claim 17, wherein, The notch is spaced apart from the contact portion.

19. The secondary battery according to claim 18, wherein, The lower cover is disc-shaped and includes: The support portion is located below the exhaust plate; and The connecting portion extends inward from the supporting portion and is electrically connected to the contact portion of the exhaust plate.

20. The secondary battery according to claim 19, further comprising: The first electrode terminal is electrically connected to the first electrode plate of the electrode assembly and the closed end of the can; as well as The second electrode terminal is electrically connected to the lower surface of the support portion and the second electrode plate of the electrode assembly.

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