Secondary battery in which metal member is inserted into can body to improve safety

Abstract

The present invention relates to a secondary battery in which an electrode assembly including a positive electrode, a separator, and a negative electrode is accommodated together with an electrolyte solution in a battery case, in which the battery case is made of metal and includes a can body including an accommodation portion for accommodating the electrode assembly and the electrolyte solution and being open at an upper portion of the can body, and a cap assembly coupled to the open upper portion of the can body, in which the can body includes a curled portion inwardly curved at an upper portion of the accommodation portion, and a crimped portion curved from an upper portion of the curled portion in a direction toward the cap assembly, in which a metal member is inserted into at least one of a bottom portion of the can body and the crimped portion, and a melting point of the metal member is lower than a melting point of a metal of the can body.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of Korean Patent Application No. 10-2021-0069475, filed with the Korean Intellectual Property Office on May 28, 2021, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure relates to a secondary battery in which metal components are inserted into a canister to improve safety. Background Technology

[0004] Due to the rapid increase in the use of fossil fuels, the demand for alternative or clean energy sources is growing, and as part of this, the most active area of ​​research is the use of electrochemistry for power generation and energy storage.

[0005] Currently, secondary batteries are a representative example of electrochemical devices that utilize such electrochemical energy, and their application tends to gradually expand.

[0006] In recent years, with the increasing development of mobile devices such as portable computers, mobile phones, and camera devices, the demand for secondary batteries as energy sources for these devices has also increased dramatically. Among such secondary batteries, lithium-ion batteries exhibit high charge / discharge characteristics, long lifespan, and are environmentally friendly. Extensive research has been conducted on lithium-ion batteries, and they are now commercialized and widely used.

[0007] Furthermore, with growing concern for environmental issues, research on electric vehicles and hybrid electric vehicles is frequently conducted. These vehicles can replace fossil fuel-powered vehicles, such as gasoline and diesel vehicles, which are major contributors to air pollution. Although nickel-metal hydride batteries are primarily used as the power source for electric and hybrid electric vehicles, research on the use of lithium-ion batteries with high energy density and high discharge voltage is also actively underway, with some already in the commercialization stage.

[0008] Depending on the shape of the battery case, secondary batteries can typically include: cylindrical or prismatic secondary batteries that house stacked / folded or rolled electrode assemblies within a metal case serving as the battery case; pouch-type secondary batteries that incorporate stacked or stacked / folded electrode assemblies within a pouch-type battery case made of aluminum laminate; and so on.

[0009] Meanwhile, when cylindrical batteries are used as batteries for electric vehicles, the safety aspects of cylindrical batteries are becoming an increasingly important issue.

[0010] In particular, when a fire occurs in a vehicle, the ignition of one cylindrical battery that affects other batteries can lead to a chain reaction of fires, which could result in a larger accident.

[0011] Therefore, when the battery is exposed to high temperatures and catches fire, the side surface of the cylindrical can is damaged, and this situation needs to be resolved, but the current design of the cylindrical can does not guarantee that the side surface of the can will not be damaged.

[0012] Therefore, there is a need to develop technologies for secondary batteries that can solve these problems and prevent damage to the side surfaces of the battery. Summary of the Invention

[0013] [Technical Issues]

[0014] This disclosure was designed to address the problems mentioned above and other unresolved technical issues.

[0015] Specifically, the purpose of this disclosure is to provide a secondary battery that can prevent damage to the side surface of the canister and minimize the impact on surrounding secondary batteries to prevent continuous ignition, and the secondary battery also ensures that the pressure effect caused by pressure rise during internal ignition of the secondary battery is applied to the upper and lower ends of the canister rather than the side surface.

[0016] [Technical Solution]

[0017] According to one embodiment of this disclosure, a secondary battery is provided, wherein an electrode assembly including a cathode, a separator, and an anode, together with an electrolyte solution, is housed in a battery case.

[0018] The battery box is made of metal.

[0019] The battery case includes: a canister comprising a housing portion for accommodating electrode assemblies and an electrolyte solution, and the canister being open at the top; and a cover assembly coupled to the top of the opening in the canister.

[0020] The tank body includes: an inwardly curved flange at the upper part of the shell portion; and a crimped portion at the upper part of the flange that is curved in the direction of the cover assembly.

[0021] At least one of the bottom or crimping portion of the tank body has a metal member inserted therein, and

[0022] The melting point of the metal components is lower than that of the metal in the tank.

[0023] The tank body can be made of metal with a melting point of 1000°C to 2000°C, and the metal components can be made of metal with a melting point of 200°C to 600°C.

[0024] Specifically, the battery box may be made of a metal selected from the group consisting of aluminum, nickel, stainless steel (SUS), copper, iron, bronze and brass, and the metal components may be made of a metal selected from the group consisting of tin (Sn), zinc (Zn) and lead (Pb).

[0025] In addition, metal components may be included in both the bottom of the tank and the crimped portion.

[0026] The planar shape of the metal component contained in the bottom of the tank can be polygonal, circular or elliptical, and the metal component contained in the crimping portion can be included in a continuous or discontinuous strip shape formed in the circumferential direction of the crimping portion.

[0027] In the bottom of the tank, the metal component may be included in an area of ​​10% to 90% of the total area of ​​the bottom, and in the crimping part, the metal component may be included in an area of ​​10% to 90% of the total area of ​​the crimping part.

[0028] In addition, the metal components may be included with a thickness of 10% to 90%, preferably 20% to 90%, of the metal thickness forming the tank.

[0029] In one specific embodiment, the can body may be a cylindrical box, and the electrode assembly may be a wound or stacked / folded electrode assembly. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a secondary battery according to an embodiment of the present disclosure;

[0031] Figure 2 yes Figure 1 A top view of the bottom of the secondary battery; and

[0032] Figure 3 It is to virtually extend the portion corresponding to the crimped part along the circumferential direction in order to show Figure 1 A schematic diagram showing the state of the metal components in the crimping part of the secondary battery. Detailed Implementation

[0033] In order to better understand this disclosure, it will be described in more detail below.

[0034] The terms or words used in this specification and claims should not be construed as being limited to common or dictionary terms, and should be interpreted in a meaning and concept consistent with the technical concept of this disclosure based on the principle that the inventor can appropriately define the concepts of the terms to best describe the disclosure.

[0035] The technical terminology provided herein is for the purpose of describing only particular embodiments and is not intended to limit this disclosure. The singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0036] The terms “including” or “comprising” as used herein specify a particular feature, integer, step, action, component or combination thereof, but do not preclude the presence or addition of different particular features, integers, steps, components and / or combinations thereof.

[0037] According to one embodiment of this disclosure:

[0038] A secondary battery is provided, wherein an electrode assembly including a cathode, a separator, and an anode, together with an electrolyte solution, is housed in a battery case.

[0039] The battery box is made of metal.

[0040] The battery case includes: a canister comprising a housing portion for accommodating electrode assemblies and an electrolyte solution, and the canister being open at the top; and a cover assembly coupled to the top of the opening in the canister.

[0041] The tank body includes: an inwardly curved flange at the upper part of the shell portion; and a crimped portion at the upper part of the flange portion that is curved in the direction of the cover assembly.

[0042] At least one of the bottom or crimping portion of the tank body has a metal member inserted therein, and

[0043] The melting point of the metal components is lower than that of the metal in the tank.

[0044] Below, the term "metal" is a concept that includes not only single metals but also alloys.

[0045] In this case, the can is not limited as long as it is a metal with a high melting point, and for example, the can can be made of a metal with a melting point of 1000°C to 2000°C. More specifically, the can can be made of a metal selected from any of the group consisting of aluminum, nickel, stainless steel (SUS), copper, iron, bronze, and brass.

[0046] Here, when at least one of the above materials is included, the metal comprising any one of them is a concept that includes all alloys or a single metal.

[0047] However, specifically, the tank can be made of iron or stainless steel.

[0048] Meanwhile, the metal components can be made of metals with a melting point lower than that of the metals (alloys or single metals) that make up the tank.

[0049] Specifically, if the melting point of the metal component is lower than that of the metal in the can, the type of metal component is not limited. However, for example, the metal component can be made of a metal with a melting point of 200°C to 600°C, and more specifically, the metal component can be made of a metal selected from any of the group consisting of tin (Sn), zinc (Zn), and lead (Pb).

[0050] This is also the same as the description of the metal of the tank, and specifically, the metal components can be tin or zinc.

[0051] When a metal component with a low melting point is included in the metal forming the bottom or crimp portion of the can as described above, during internal ignition of the secondary battery, as the temperature rises, the bottom and / or crimp portion of the can becomes weaker, and therefore, the effect of pressure due to the increased pressure is applied to the bottom or crimp portion, thereby minimizing the effect of pressure on the side surface of the can and thus reducing the impact on the surrounding secondary batteries.

[0052] In this disclosure, Figure 1 The diagram shows a schematic of such a secondary battery.

[0053] Reference Figure 1 The secondary battery 100 according to the present disclosure is formed by an electrode assembly 120 including a cathode, a separator and an anode, together with an electrolyte solution, being housed in a can 110. The can 110 includes a housing portion 111 serving as a battery case and is open at the top of the can 110, and a cover assembly 130 is coupled to the top of the opening of the can 110.

[0054] Among them, tank 110 is a cylindrical box.

[0055] The tank body 110 includes: a shell portion 111 that supports the electrode assembly 120 and includes a bottom 114 and a side surface extending upward from the bottom; a rolled edge portion 112 that bends inward at the upper part of the shell portion 111; and a crimping portion 113 that bends at the upper part of the rolled edge portion 112 in the direction of the cover assembly 130.

[0056] At this time, in the bottom 114 and the crimping part 113 of the tank body 110, the corresponding metal components 160 and 170 are inserted into the metal forming the bottom 114 and the crimping part 113.

[0057] Of course, the metal component can be included in at least one of the bottom 114 and the crimping portion 113, but to further reduce the impact on the side surfaces of the can 110, it is advantageous to apply pressure to both the upper and lower sides. Therefore, more preferably, as Figure 1 In this manner, metal components 160 and 170 are respectively inserted into the bottom 114 and the crimping portion 113.

[0058] Meanwhile, the corresponding metal components 160 and 170 only need to be included in the bottom 114 and the crimping portion 113 of the tank body 110 to achieve the effect planned by this disclosure, and the shape, area, thickness, etc. of the metal components are not limited.

[0059] In this regard, to illustrate the metal component 160 inserted into the bottom 114 of the can body 110, Figure 2 A schematic top view of the bottom 114 is shown.

[0060] Reference Figure 2 The planar shape of the metal component 160 inserted into the bottom 114 of the can 110 can be polygonal (a), circular (b) or elliptical (c), and the planar shape is not limited.

[0061] At the same time, the planar area of ​​the metal component 160 is not particularly limited, as long as the area is sufficient to demonstrate the intended effect of this disclosure. However, in order to effectively demonstrate the intended effect of this disclosure, the area (S) can be 10% to 90%, specifically 20% to 90%, and more specifically 30% to 80% of the total area (A) of the bottom 114.

[0062] If the area is too small and falls outside the above range, the intended effect of this disclosure may not be significant, while if the area is too large, the rigidity of the tank 110 itself may be weakened, which is not preferred.

[0063] at the same time, Figure 3 The following state is schematically shown: the portion corresponding to the crimping portion 113 is virtually extended in the circumferential direction to illustrate the metal member 170 inserted into the crimping portion 113 of the can body 110.

[0064] The metal member 170 included in the crimping portion 113 is not limited in its shape, but is preferably formed from the side surface along the circumferential direction. Therefore, as... Figure 3 As shown, the metal member 170 may be included in a strip shape in part or all of the longitudinal direction around the crimp portion 113.

[0065] Meanwhile, the metal component 170 may include, for example, Figure 3 In the continuous strip shape shown in (a), and can be formed in, for example Figure 3 In the discontinuous strip shape shown in (b).

[0066] Additionally, similar to the bottom 114, the forming area (S') of the metal component 170 can be considered to demonstrate the extent to which the intended effect of this disclosure is achieved. a +S' b +S' c +S' d The area (S') is not limited. However, in order to effectively demonstrate the effects planned in this disclosure, the area (S') may be 10% to 90% of the total area (A') of the crimping portion 113, specifically 20% to 90%, and more specifically 30% to 80%.

[0067] Here, in the standard used to describe area, the following portion relative to the rolled edge 112 is considered as the crimped portion 113: a straight portion formed from the curved portion away from the rolled edge 112 in a direction parallel to the insertion direction of the electrode assembly 120 to the end of the can body 110 that is bent in the direction of the cover assembly 130 and coupled to the cover assembly 130.

[0068] The meaning of the numerical limit is the same as the rationale for the numerical limit on the area of ​​the metal component 160 at the bottom 114.

[0069] At the same time, refer to again Figure 1 The thickness t of the corresponding metal members 160 and 170 in the bottom 114 and / or crimping portion 113 of the can body 110 may include 10% to 90%, more specifically 20% to 80%, and more specifically 30% to 60% of the metal thickness T forming the can body 110.

[0070] If the thickness is too thin and falls outside the above range, the intended effect of this disclosure may not be significant, while if the thickness is too thick, the rigidity of the tank 110 itself may be weakened, which is not preferred.

[0071] The configurations of other secondary batteries will be described in detail below.

[0072] Electrode assembly 120 is, but is not limited to, a wound or stacked / folded electrode assembly.

[0073] The wound electrode assembly is manufactured by inserting and winding sheet spacers between sheet cathodes and sheet anodes.

[0074] Stacked / folded electrode assemblies are manufactured by winding unit electrodes, unit electrodes and separators on a sheet separator film, stacking fully charged cells such that electrodes of the same polarity are positioned at both ends, and stacking two cells such that electrodes of different polarities are positioned at both ends.

[0075] The specific configurations of such wound electrode assemblies and stacked / folded electrode assemblies are conventionally known, and therefore their detailed descriptions will be omitted in this document.

[0076] Furthermore, since the specific configuration of the electrode assembly, as well as the specific descriptions of the cathode, anode, separator, and electrolyte solution, are conventionally known, their detailed descriptions will be omitted herein.

[0077] Furthermore, the secondary battery 100 according to this disclosure includes a gasket 140 mounted on the upper part of the rolled edge portion 112 of the canister 110, and the cover assembly is formed by a structure including: an upper cover 131; a current interruption safety device (PTC device) 132 and a safety vent 133 for internal pressure drop, which are stacked below the upper cover 131; and a current interruption device (CID) 134 formed at the lower end of the safety vent 133.

[0078] Additionally, cathode tab 121 and anode tab 122 are removed from electrode assembly 120. Cathode tab 121 is electrically connected to cover assembly 130, and anode tab 122 is connected to bottom 114 of tank body 110.

[0079] Here, the current interruption safety device 132, the safety vent 133, and the current interruption device 134 are preferably the entire structure through which the current flows, and are configured to ensure the safety of the secondary battery.

[0080] Since other specific details are generally known, their descriptions will be omitted in this article.

[0081] Furthermore, the secondary battery 100 according to this disclosure includes a center pin 150 having a hollow structure that is inserted into the center of the electrode assembly 120.

[0082] At this time, similar to the can body 110, the center pin 150 may also be made of metal, specifically including any metal selected from the group consisting of aluminum, nickel, stainless steel (SUS), copper, iron, bronze and brass.

[0083] Those skilled in the art will be able to make various applications and modifications based on the above content within the scope of this disclosure.

[0084] [Industrial Applicability]

[0085] As described above, the secondary battery according to embodiments of the present disclosure is configured such that a metal member with a melting point lower than that of the metal constituting the can is inserted into the bottom and / or crimping portion of the battery box can. During internal ignition of the secondary battery, as the temperature rises, the bottom and / or crimping portion of the can becomes weaker, and the pressure effect caused by the pressure increase is applied to the lower and upper ends of the secondary battery, thereby minimizing the pressure effect on the side of the can, thereby reducing the impact on the surrounding secondary batteries and preventing chain fires.

Claims

1. A secondary battery, wherein, The electrode assembly, including the cathode, separator, and anode, along with the electrolyte solution, is housed in the battery case. The battery box is made of metal. The battery case includes: a canister comprising a housing portion for accommodating the electrode assembly and the electrolyte solution, and the canister being open at its upper portion; and a cover assembly coupled to the upper portion of the opening in the canister. The can body includes: an inwardly curved rolled edge at the upper part of the shell portion; and a crimped portion at the upper part of the rolled edge that is curved in the direction of the cover assembly. Wherein, at least one of the bottom of the can body or the crimping portion has a metal member inserted inside the metal forming the bottom or the crimping portion. Wherein, the melting point of the metal component is lower than the melting point of the metal in the can body, and The metal components are included in a thickness of 10% to 90% of the metal thickness forming the tank body.

2. The secondary battery according to claim 1, wherein: The tank body is made of a metal with a melting point of 1000°C to 2000°C, and The metal component is made of a metal with a melting point of 200°C to 600°C.

3. The secondary battery according to claim 1, wherein: The battery box is made of a metal selected from the group consisting of aluminum, nickel, stainless steel (SUS), copper, iron, bronze, and brass. The metal component is made of a metal selected from the group consisting of tin (Sn), zinc (Zn) and lead (Pb).

4. The secondary battery according to claim 1, wherein: The metal component is included in both the bottom of the tank and the crimping portion.

5. The secondary battery according to claim 1, wherein: The planar shape of the metal component contained in the bottom of the tank is polygonal, circular, or elliptical.

6. The secondary battery according to claim 1, wherein: The metal member contained in the crimping portion is included in a continuous or discontinuous strip shape formed in the circumferential direction of the crimping portion.

7. The secondary battery according to claim 1, wherein: The metal component is included in the bottom of the tank, comprising 10% to 90% of the total area of ​​the bottom. In the crimping portion, the metal component is included in an area of ​​10% to 90% of the total area of ​​the crimping portion.

8. The secondary battery according to claim 1, wherein: The container is a cylindrical box.

9. The secondary battery according to claim 1, wherein: The electrode assembly is a wound electrode assembly or a stacked / folded electrode assembly.

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