Cylindrical battery with enhanced sealing

Abstract

The present invention relates to: a cylindrical battery comprising a cylindrical can receiving an electrode assembly, a cap assembly mounted on an opening portion of the cylindrical can, and a gasket interposed between the cylindrical can and the cap assembly, in which the cylindrical can is provided at an upper portion thereof with a crimping portion wrapping an outer periphery of the gasket, a bent part further bent into the gasket is arranged at the tail end of the crimping part, and the length of the bent part is smaller than 0.175 mm; a method for sealing a cylindrical battery; and a crimping device for a cylindrical battery. The present invention solves the problem of sealing degradation caused by primary crimping to which primary pressure is applied and secondary crimping to which secondary pressure is applied when a cylindrical battery is sealed by a crimping portion. Correspondingly, the sealing of the cylindrical battery according to the invention is further enhanced by secondary sealing.

Description

Technical Field

[0001] The present invention relates to a cylindrical battery with enhanced sealing, and more particularly to a cylindrical battery with a crimping portion for enhanced sealing, a sealing method for a cylindrical battery, and a crimping device for a cylindrical battery. Background Art

[0002] Lithium secondary batteries are classified into cylindrical batteries, prismatic batteries, and pouch batteries based on the shape of the battery case. Cylindrical batteries have an electrode assembly housed in a cylindrical metal can; prismatic batteries have an electrode assembly housed in a prismatic metal can; and pouch batteries have an electrode assembly housed in a pouch-shaped case made of aluminum laminate. Cylindrical batteries have the advantages of relatively large capacity and structural stability.

[0003] Figure 1 and Figure 2 are cross-sectional views showing two examples of typical cylindrical batteries. Figure 1 and Figure 2 In the present invention, a cylindrical battery includes an electrode assembly including a positive electrode, a negative electrode, and a separator. The cylindrical battery includes a cylindrical can, a cap assembly, and a gasket. The cylindrical can includes an upper end opening. The cap assembly is coupled to the cylindrical can via a press-fit portion formed on the outer circumferential surface of the upper portion of the cylindrical can. The press-fit portion is formed by inward bending of a portion of the upper end opening. The gasket is interposed between the cylindrical can and the cap assembly.

[0004] A crimping portion is formed at the upper end of the cylindrical can to allow the cap assembly to be installed on the open end of the cylindrical can. More specifically, the crimping portion is formed by crimping the upper end of the cylindrical can to form an inward recess, attaching a gasket to the open end, sequentially inserting the outer circumferential surfaces of the top cap, the PTC element, and the safety vent, and then bending the upper end of the cylindrical can inward. Thus, the crimping portion is formed to enclose the gasket located on the inner surface of the crimping portion, and the cap assembly is installed by performing crimping and pressing.

[0005] The crimping portion has a structure in which the distal end of the crimping portion is bent inward, so that the cap assembly can be securely attached to the open upper end of the cylindrical can with the gasket inserted between the cap assembly and the cylindrical can. The side walls of such a crimping portion are formed vertically in the same manner as the side surfaces of the battery.

[0006] The material of the cylindrical tank is not particularly limited, and the cylindrical tank can be made of any one of stainless steel, steel, aluminum or their equivalents. Because the cylindrical tank must be conductive, metal parts are used, and such metal parts may be easily corroded due to contact with external moisture.

[0007] Reference Figure 1 The cylindrical battery 100 includes a cylindrical can 20, a cap assembly 30 and a gasket 40, the electrode assembly 10 is received in the cylindrical can 20 together with the electrolyte, the cap assembly 30 is airtightly connected to the open end of the cylindrical can 20, and the gasket 40 is placed between the cylindrical can 20 and the cap assembly 30.

[0008] The cap assembly 30 may include a top cap and a safety vent 36, the top cap being configured to seal the open end of the cylindrical can 20, one surface of the safety vent 36 being in contact with all of the side, upper, and lower surfaces of the top cap, and the other surface of the safety vent 36 being bent and arranged to contact the inner surface of the gasket 40, the safety vent being electrically connected to the electrode assembly 10.

[0009] A battery including such a cap assembly 30 can provide instantaneous high output when used as a power source for an electric tool such as an electric drill, and can be stable against external physical impacts such as vibration or dropping.

[0010] In the cap assembly 30 in which the safety vent 36 is bent to wrap around the top cover, the contact surface between the safety vent 36 and the top cover may form one or more connection portions formed by welding or the like. The term "welding" as used in the present invention is intended to include not only welding in the literal sense of the term, such as laser welding, ultrasonic welding, and resistance welding, but also fastening methods such as brazing, etc. Welding may be performed during assembly of the cap assembly 30 itself, or may be performed while the cap assembly 30 is mounted on the cylindrical can 20.

[0011] The safety vent 36 is used to cut off the current or discharge gas when the pressure in the battery increases, and is preferably made of metal. The thickness of the safety vent 36 can vary depending on the material and structure, and is not particularly limited, as long as the safety vent can rupture to discharge gas when the predetermined high pressure in the battery is reached. The thickness of the safety vent 36 can be, for example, 0.2 mm to 0.6 mm.

[0012] The thickness of the top cover, which contacts the safety vent 36, is not particularly limited, as long as it can protect the various components of the cap assembly 30 from external pressure. For example, the thickness of the top cover can be 0.3 mm to 0.5 mm. If the thickness of the top cover is too small, the mechanical rigidity is insufficient, which is not ideal. On the other hand, if the thickness of the top cover is too large, the size and weight increase, and the capacity of the battery may be reduced compared to batteries of the same specifications, which is also not ideal.

[0013] Preferably, the gasket 40 has an overall cylindrical shape with an open end, wherein one end of the gasket facing the inner surface of the cylindrical can 20 is bent toward the center at a right angle to rest on the open end, i.e., the crimped portion, of the cylindrical can 20. The other end of the gasket 40 is initially straight and faces the axial direction of the cylindrical gasket 40, and is bent toward the center at a right angle during the pressing of the cylindrical can 20, so that the inner and outer peripheral surfaces of the gasket are folded into close contact with the top cover of the cap assembly 30 and the inner surface of the cylindrical can 20, respectively.

[0014] The gasket 40 is made of an electrically insulating elastic polymer resin, ideally one that is electrically insulating, impact-resistant, resilient, and durable. Typically, the gasket must be insulating, have excellent chemical resistance to the electrolyte to prevent leakage, and be heat-resistant, as it must maintain airtightness under the harsh conditions of high temperature and humidity found in batteries. Such gaskets are typically made of polypropylene; however, the present invention is not limited thereto. Additionally, the gasket 40 may include a vaporizable rust inhibitor.

[0015] The electrode assembly 10 preferably has a structure in which two electrode plates 11 having different polarities and having a rolled wide plate shape and a separator 12 placed between the electrode plates 11 to insulate such electrode plates 11 from each other or provided on the left or right side of either electrode plate 11 are wound in a so-called "wound form." Of course, the electrode assembly may be constructed in a form in which positive and negative electrode plates having a predetermined standard are stacked with a separator interposed therebetween.

[0016] Each of the two electrode plates 11 has a structure in which an active material slurry is applied to a current collector in the form of a metal foil or metal mesh comprising aluminum or copper. The slurry is typically formed by stirring granular active material, auxiliary conductor, binder, plasticizer, etc. in the presence of a solvent. The solvent is removed in a subsequent process. In the direction in which the electrode plate 11 is wound, there may be uncoated portions to which the slurry is not applied at the starting and ending portions of the current collector. A pair of leads corresponding to each electrode plate 11 is attached to the uncoated portions. A first lead 13 attached to the upper end of the electrode assembly 10 is electrically connected to the cap assembly 30, and a second lead (not shown) attached to the lower end of the electrode assembly 10 is connected to the bottom of the cylindrical can 20. Of course, both the first lead 13 and the second lead can be led out in the direction toward the cap assembly 30. Preferably, the electrode assembly 10 is disposed on a first insulating plate (not shown) mounted on the bottom of the cylindrical can 20, and a second insulating plate (not shown) is disposed on the upper end of the electrode assembly 10. The first insulating plate insulates the electrode assembly 10 and the bottom of the cylindrical can 20 from each other, and the second insulating plate insulates the electrode assembly 10 and the cap assembly 30 from each other.

[0017] The cylindrical can 20 is made of a lightweight conductive metal material, such as aluminum or an aluminum alloy, and has a cylindrical structure with an open top and a closed bottom opposite to the open top. The electrode assembly 10 and the electrolyte (not shown) are received in the internal space of the cylindrical can 20. The electrolyte is configured to move lithium ions generated by the electrochemical reaction between the electrode plates 11 during charging and discharging of the secondary battery 100. Such an electrolyte can be a non-aqueous organic electrolyte, which is a mixture of a lithium salt and a high-purity organic solvent, or a polymer using a polymer electrolyte, but the type of electrolyte is not limited in the present invention.

[0018] Meanwhile, a center pin (not shown) may be inserted into the center of the cylindrical can 20, the center pin being configured to prevent the electrode assembly 10 wound in a jelly-like form from being unwound and serving as a passage for movement of gas in the secondary battery 100. The upper portion of the cylindrical can 20, that is, the upper end portion of the electrode assembly 10, is provided with a beading portion 24 that is bent by being pressed from the outside toward the inside to prevent the electrode assembly 10 from moving in the up and down directions.

[0019] The cap assembly 30, which is assembled to the opening of the cylindrical can 20 in an airtightly sealed state through the gasket 40, includes a top cap and a safety vent 36. The top cap has an electrode terminal (not shown) formed for electrical connection to the outside. The safety vent 36 is bent so as to wrap around the outer peripheral surface of the top cap.

[0020] The cylindrical battery 100 may further include a current interruption device welded to the lower end of the safety vent 36, which is connected to the electrode assembly 10. Specifically, the safety vent 36 may be convex at its center and welded to a current interruption device (CID) 38, wherein the current interruption device 38 may be deformable together with the safety vent 36 by the internal pressure of the secondary battery 100 and may be divided into a CID gasket and a CID filter.

[0021] The cylindrical battery 100 may further include an auxiliary gasket. The auxiliary gasket 42 is a gasket for the current interrupt device 38 and is configured to wrap around the outer peripheral surface of the current interrupt device 38. Specifically, the auxiliary gasket 42 contacts the upper and side portions of the outer peripheral surface of the current interrupt device 38 and supports the upper and side portions of the current interrupt device 38. Furthermore, the auxiliary gasket 42 serves to electrically isolate the current interrupt device 38 from the safety vent 36, except for the portion where the protruding portion of the safety vent 36 contacts the current interrupt device 38.

[0022] The positive electrode lead welded to the positive electrode foil of the wound electrode assembly 10 is electrically connected to the cap assembly 30 and connected to the protruding terminal on the upper end of the top cover, and the negative electrode lead welded to the negative electrode foil is welded to the closed end of the cylindrical can 20, so that the cylindrical can 20 itself constitutes the negative terminal. The material of the cylindrical can 20 is not particularly limited and can be any one of stainless steel, steel, aluminum, and their equivalents. In a state where the electrode assembly 10 is received in the cylindrical can 20, the electrolyte is injected into the cylindrical can, and the assembly of the secondary battery is completed by installing the cap assembly 30 to the open end of the cylindrical can 20 to seal the cylindrical can.

[0023] The secondary battery can be a lithium (ion) secondary battery with high energy density, high discharge voltage and high output stability. Such a lithium secondary battery includes a positive electrode, a negative electrode, a separator 12 and a non-aqueous electrolyte containing lithium salt, etc. For example, the positive electrode is manufactured by applying a mixture of a positive electrode active material, a conductive agent and a binder to a positive electrode current collector and drying it, and a filler can be further added as needed. The negative electrode is manufactured by applying a negative electrode active material to a negative electrode current collector and drying it, and the above components can be further included as needed. The separator 12 is inserted between the negative electrode and the positive electrode, and an insulating film with high ion permeability and mechanical strength is used. The non-aqueous electrolyte containing lithium salt consists of a non-aqueous electrolyte and a lithium salt, and a liquid non-aqueous electrolyte, a solid electrolyte or an inorganic solid electrolyte, etc. are used as the non-aqueous electrolyte. Here, the current collector, the electrode active material, the conductive agent, the binder, the filler, the separator 12, the electrolyte and the lithium salt, etc. are widely known in the art, and their detailed description will be omitted.

[0024] Figure 2 is a cross-sectional view showing another example of a conventional cylindrical battery. Figure 2 In the reference numerals described in Figure 1 Components with the same reference numerals are identical components having the same functions. Figure 2 The cap assembly 30 may include a top cap, a positive temperature coefficient (PTC) element 34, and a safety vent 36, the top cap being configured to seal the open end of the cylindrical can 20 and contacting a protrusion of a gasket 40, the positive temperature coefficient element 34 being configured to contact the top cap, and the safety vent 36 having one surface configured to contact the PTC element 34 and another surface configured to contact the gasket 40. The gasket 40 may be in contact with Figure 1 Same pads used in the.

[0025] The PTC element 34 is used to block current by significantly increasing the battery's resistance when the temperature in the battery rises. The thickness of such a PTC element 34 can also vary depending on the material and structure, and can be, for example, 0.2 mm to 0.4 mm. If the thickness of the PTC element 34 is greater than 0.4 mm, the internal resistance increases, and the size of the battery may increase, which may reduce the battery's capacity relative to batteries of the same size. On the other hand, if the thickness of the PTC element 34 is less than 0.2 mm, it will be difficult to achieve the required current blocking effect at high temperatures, and the PTC element may be damaged even by a weak external impact. Therefore, by taking these points into consideration, the thickness of the PTC element 34 can be appropriately determined within the above thickness range.

[0026] The thickness of the top cover in contact with the PTC element 34 is not particularly limited, as long as the thickness is within a range that can protect the various components of the cap assembly 30 from externally applied pressure, and the thickness of the top cover can be, for example, 0.3 mm to 0.5 mm. If the thickness of the top cover is too small, the mechanical rigidity is insufficient, which is not ideal. On the other hand, if the thickness of the top cover is too large, the size and weight increase, and the capacity of the battery may be reduced compared to batteries with the same specifications, which is also not ideal.

[0027] The secondary battery including the cap assembly 30 including the top cap, the PTC element 34 and the safety vent can be used as a power source for mobile phones, notebook computers and the like that require reliable, constant output.

[0028] The present invention relates to a cylindrical battery with enhanced sealing, and more particularly, to a cylindrical battery with a crimping portion with enhanced sealing, and hereinafter, components related to the sealing of the crimping portion, namely, the crimping portion, the crimping portion, the gasket, the cylindrical can and the cover assembly will be schematically shown and described.

[0029] The cylindrical battery has a structure in which an open end is formed and sealing is achieved by a crimping portion formed at the open end. The cylindrical battery is sealed by mechanical pressing, and when sealing is performed by mechanical pressing, when a small gap appears between the two joints, the gap may serve as a leakage path. Therefore, the cylindrical battery has a disadvantage that the sealing characteristics are lower than those of the pouch-shaped battery. When the cylindrical battery is used as a power source for electric vehicles, hybrid vehicles, etc., the sealing characteristics of the battery are very important due to the required long life and high density of the battery cells.

[0030] A great deal of research has been conducted on the sealing of can-shaped batteries including cylindrical batteries.

[0031] Patent Document 1 describes a configuration in which an O-shaped positive electrode ring is inserted into the space formed between the gasket and the sealing can to fill the space, and Patent Document 2 describes a configuration in which a sealing film is used to improve the airtightness of the internal space between the gasket and the can. Patent Document 3 describes a configuration in which the spaces between the gasket and the can, and between the can and the positive electrode plate, are filled with a sealant and an adhesive to improve sealing performance and provide electrical insulation.

[0032] The positive electrode rings and sealing films of Patent Documents 1 and 2 serve only to seal the space between the gasket and the sealed can, and do not specify essential gasket features such as electrical insulation and corrosion protection. Therefore, the positive electrode rings do not appear to function as gaskets. The sealant and adhesive of Patent Document 3 are not components but rather materials that fill the spaces between the gasket and can, and between the can and the positive electrode plate. Even if the sealant and adhesive have insulating and sealing functions, it is impossible to equate them with gaskets. Furthermore, the configuration of the injected sealant and adhesive of Patent Document 3 is solely for sealing and insulation, making it difficult to consider the sealant and adhesive as gaskets between the gasket and can, filling the minute gaps in the internal space by absorbing electrolyte.

[0033] In patent document 4, the upper end portion of the crimped portion of the cylindrical tank is bent continuously twice under predetermined conditions to suppress the opening of the sealing portion when an external physical shock, such as vibration or dropping, is applied or when the internal pressure increases, thereby preventing electrolyte leakage and minimizing deformation, such as wrinkles, formed in the tank when bent with a small curvature radius.

[0034] Patent document 5 relates to a cylindrical battery, which includes a primary crimping mold and a secondary crimping mold, the primary crimping mold is configured to apply primary pressure so that the end of the top opening forms an inclined surface inclined toward the central axis of the metal can in a vertical section, and the secondary crimping mold is configured to apply secondary pressure to the end of the top opening formed with the inclined surface to form a flat section parallel to the lower surface of the metal can on the crimping portion, wherein a flat section corresponding to the flat section is formed on the lower surface of the end of the second crimping mold facing the top opening so as to form a flat section on the crimping portion.

[0035] Patent Document 4 aims to enhance sealing, but fails to recognize that bending of the crimping portion may cause abnormal phenomena. Patent Document 5 only aims to form a flat section at the crimping portion to facilitate welding, but does not provide a solution to enhance sealing.

[0036] In particular, the inventors of the present invention have observed an unusual phenomenon in which sealing (pressing force) decreases if secondary or more additional crimping is performed in addition to primary crimping, but existing literature has neither recognized this nor provided a solution thereto.

[0037] Regarding the above configuration, simulation results show that the pressing force of the crimping portion varies between +, 0, or - depending on the bend length or bend angle. While it is generally recognized that the pressing force increases when a bend is provided, the simulation results show a negative effect of reduced crimping force beyond a certain length, which would not be easily anticipated by those skilled in the art.

[0038] Japanese Patent Application Publication No. 2016-213126 (“Patent Document 1”)

[0039] Japanese Patent Application Publication No. 2004-079355 ("Patent Document 2")

[0040] Japanese Registered Patent Publication No. 5238153 (“Patent Document 3”)

[0041] Korean Patent Application Publication No. 2008-0053538 (“Patent Document 4”)

[0042] Korean Patent Application Publication No. 2018-0072990 (“Patent Document 5”) Summary of the Invention

[0043] Technical issues

[0044] The present invention is made in view of the above problems, and an object of the present invention is to provide a cylindrical battery having a crimping portion for enhancing sealing and a method for enhancing the sealing of the crimping portion of a cylindrical battery, wherein the crimping portion is constructed so that when sealing is performed by the crimping portion of the cylindrical battery, the problem of sealing deterioration caused by primary crimping applying primary pressure and secondary crimping applying secondary pressure is solved.

[0045] Here, secondary crimping refers to additional crimping performed after primary crimping, and more specifically, secondary crimping refers to a process of crimping the last bent portion of the crimped portion.

[0046] Technical Solution

[0047] To achieve the above object, the present invention provides a cylindrical battery comprising: a cylindrical can configured to receive an electrode assembly; a cap assembly mounted to an opening of the cylindrical can; and a gasket interposed between the cylindrical can and the cap assembly, wherein

[0048] The cylindrical can is provided with a crimping portion at its upper portion, the crimping portion being configured to wrap around the outer periphery of the liner, and the crimping portion is provided with a bent portion at its end that is further bent into the liner, and the length of the bent portion is less than 0.175 mm. The length of the bent portion corresponds to less than 31.8% of the thickness of the liner.

[0049] The length of the bent portion may be 0.15 mm or less. The length of the bent portion corresponds to 27.2% or less of the thickness of the gasket.

[0050] The bending angle of the bent portion may be from 15 degrees downward from the horizontal to 90 degrees at right angles to the horizontal.

[0051] The liner may include polybutylene terephthalate (PBT).

[0052] The crimping portion may include a horizontal portion provided at an uppermost end portion thereof, the horizontal portion forming a horizontal plane, and the bent portion may be provided at a distal end of the horizontal portion.

[0053] The length of the horizontal portion may be 0.9 mm or greater.

[0054] The thickness of the cylindrical can may be 0.3 mm or more.

[0055] In addition, the present invention provides a sealing method for a cylindrical battery, the cylindrical battery including: a cylindrical can configured to receive an electrode assembly; a cap assembly mounted to an opening of the cylindrical can; and a gasket interposed between the cylindrical can and the cap assembly, the sealing method comprising:

[0056] The steps of bending the upper portion of the cylindrical can to form a crimped portion configured to wrap around the outer periphery of the liner; and further bending the distal end of the crimped portion into the liner to form a bent portion, wherein the bent portion has a length of less than 0.175 mm. The length of the bent portion corresponds to less than 31.8% of the thickness of the liner.

[0057] In addition, the length of the bent portion may be 0.15 mm or less. The length of the bent portion corresponds to 27.2% or less of the thickness of the gasket.

[0058] The bending angle of the bent portion may be from 15 degrees downward from the horizontal to 90 degrees at right angles to the horizontal.

[0059] The liner may include polybutylene terephthalate (PBT).

[0060] The crimping portion may include a horizontal portion provided at an uppermost end portion thereof, the horizontal portion forming a horizontal plane, and the bent portion may be provided at a distal end of the horizontal portion.

[0061] The length of the horizontal portion may be 0.9 mm or greater.

[0062] The thickness of the cylindrical can may be 0.3 mm or more.

[0063] In addition, the present invention provides a battery pack including the cylindrical batteries.

[0064] In addition, the present invention provides a crimping device for cylindrical batteries, the crimping device being used to crimp the upper portion of a cylindrical can of the cylindrical battery to form a crimped portion configured to wrap around the outer periphery of a gasket. The crimping device includes: three clamping jaws configured to secure the cylindrical side surface of the cylindrical can; at least one crimping unit configured to gradually crimp the cylindrical battery; and a final crimping unit configured to finally crimp the cylindrical battery. The final crimping unit further bends the distal end of the crimped portion into the gasket, the bent portion having a length of less than 0.175 mm. The bent portion length corresponds to less than 31.8% of the gasket thickness.

[0065] The length of the bent portion may be 0.15 mm or less. The length of the bent portion corresponds to 27.2% or less of the thickness of the gasket.

[0066] The bending angle of the bent portion may be from 15 degrees downward from the horizontal to 90 degrees at right angles to the horizontal.

[0067] The crimping portion may include a horizontal portion provided at an uppermost end portion thereof, the horizontal portion forming a horizontal plane, and the bent portion may be provided at a distal end of the horizontal portion.

[0068] The length of the horizontal portion may be 0.9 mm or greater.

[0069] The thickness of the cylindrical can may be 0.3 mm or more.

[0070] The present invention may provide any possible combination of the above solutions.

[0071] Beneficial effects

[0072] As is apparent from the above description, the present invention provides a cylindrical battery comprising: a cylindrical can configured to receive an electrode assembly; a cover assembly mounted to an opening of the cylindrical can; and a liner interposed between the cylindrical can and the cover assembly, wherein the cylindrical can is provided with a crimping portion at an upper portion thereof, the crimping portion being configured to wrap around an outer periphery of the liner, the crimping portion being provided with a bent portion at an end thereof that is further bent into the liner, and a length of the bent portion being less than 0.175 mm.

[0073] In addition, the present invention provides a sealing method for a cylindrical battery, which includes: a cylindrical can, which is configured to receive an electrode assembly; a cover assembly, which is mounted to the opening of the cylindrical can; and a gasket, which is inserted between the cylindrical can and the cover assembly. The sealing method includes: a step of bending the upper portion of the cylindrical can to form a crimping portion, which is configured to wrap the outer periphery of the gasket; and a step of further bending the end of the crimping portion into the gasket to form a bent portion, wherein the length of the bent portion is less than 0.175 mm.

[0074] In addition, the present invention provides a crimping device for a cylindrical battery, which is used to crimp the upper part of the cylindrical can of the cylindrical battery to form a crimping portion configured to wrap the outer periphery of the liner, and the crimping device includes: three clamping jaws, the three clamping jaws are configured to fix the cylindrical side surface of the cylindrical can; at least one crimping unit, at least one crimping unit is configured to perform step-by-step crimping on the cylindrical battery; and a final crimping unit, the final crimping unit is configured to perform final crimping on the cylindrical battery, wherein the length of the bent portion obtained by the final crimping unit further bending the end of the crimping portion into the liner is less than 0.175 mm.

[0075] Therefore, the problem of seal degradation caused by primary compression applying primary pressure and secondary compression applying secondary pressure in the sealing of the compression part of the cylindrical battery can be solved. The cylindrical battery according to the present invention is characterized in that the seal is further enhanced by the secondary sealing. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 is a cross-sectional view showing an example of a cylindrical battery.

[0077] Figure 2 is a cross-sectional view showing another example of a cylindrical battery.

[0078] Figure 3 is a schematic diagram of a crimping portion according to the present invention.

[0079] Figure 4 An example of a calculation method simulated according to the present invention is shown.

[0080] Figure 5 Another example of a calculation method simulated according to the present invention is shown.

[0081] Figure 6 Simulation results according to the present invention are shown.

[0082] Figure 7 is an exploded perspective view of a crimping apparatus according to the present invention.

[0083] Figure 8 is a cross-sectional view of a crimping apparatus according to the present invention.

[0084] Figure 9 It is a partial enlarged view of the final crimping unit according to the present invention. DETAILED DESCRIPTION

[0085] Now, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that the preferred embodiments of the present invention can be easily implemented by those skilled in the art. However, when describing the operating principles of the preferred embodiments of the present invention in detail, the detailed description of known functions and configurations incorporated herein will be omitted when it may obscure the subject matter of the present invention.

[0086] In addition, throughout the drawings, the same reference numerals will be used to refer to components that perform similar functions or operations. Throughout the specification, when a part is said to be connected to another part, the part may not only be directly connected to the other part, but also be indirectly connected to the other part via another part. In addition, the inclusion of a certain element does not mean the exclusion of other elements, but means that such elements may also be included unless otherwise mentioned.

[0087] Figure 3 is a schematic diagram of a crimping portion according to the present invention. Figure 3 2 is a simplified schematic diagram of the crimping section used in the simulation. The cylindrical battery is provided with a crimping portion 24. The gasket 40 is primarily sealed by the crimping portion 21, and the cap assembly 30 is also sealed by the gasket 40. The crimping portion 21 includes a horizontal portion 26 at its uppermost end, which forms a horizontal plane. A curved portion 25 is provided at the distal end of the horizontal portion 26. The length of the curved portion 25 and the angle 25D at which the curved portion is bent are variables used in the simulation.

[0088] Table 1 shows a simulation set in an embodiment according to the present invention.

[0089] Table 1

[0090]

[0091]

[0092] The simulation was performed using the following analytical method.

[0093] Secondary crimping was simulated by interference fit analysis. Tertiary crimping was simulated by applying hinge (edge) and boundary conditions to the bent portion of the cylindrical tank. The contact pressure of the gasket (PBT) was calculated based on the angle of the bent portion. The thickness of the gasket used in the simulation was 0.55 mm, and the material of the gasket was PBT. The physical properties of PBT were calculated for the elastic and plastic regions of PBT. If the plastic stress is 42 MPa or less, the region is considered to be an elastic region, and the stress is calculated by multiplying the elastic modulus 1567 by the elongation. For the plastic region, the plastic stress-plastic strain curve is used.

[0094] The length of the horizontal portion is calculated based on a minimum value of 0.9 mm. The material of the cylindrical can is nickel-plated steel, and the thickness of the crimping area is assumed to be 0.3 mm.

[0095] Figure 4 An example of a calculation method simulated according to the present invention is shown, and Figure 5 Another example of a calculation method simulated according to the present invention is shown.

[0096] Reference Figure 4 and Figure 5 , Figure 4 and Figure 5 The reddish portion on the left side of FIG. 1 is the portion for calculating the contact pressure. Figure 4 and Figure 5 The pressure on the inside and outside of the pad of an example is shown. The upper left side of the red part, that is, the start of the U shape is designated as zero, and the contact pressure corresponding to each part is calculated while moving along the red part. The calculation results according to the example are shown in FIG. Figure 4 and Figure 5 The contact pressure in the graph on the right is integrated over the length to calculate each contact pressure, and Figure 4 and Figure 5 All cases in the example are added together to give the total contact pressure for an instance. Figure 4 and Figure 5 The reddish colored areas in the diagram are the areas where the gasket actually seals, and the contact pressure of all these areas is calculated to determine the pressure generated by the overall seal.

[0097] Figure 6 Simulation results according to the present invention are shown.

[0098] Reference Figure 6When the length of the curved portion (bend length) is 0.15 mm or less, the contact pressure increases as the bending angle of the curved portion increases. Specifically, it was found that sealing by the additional curved portion is effective only when the curved portion length is 0.15 mm or less, while the sealing effect is reversed when the curved portion length exceeds 0.15 mm. This length corresponds to 27.3% or less of the gasket thickness of 0.55 mm.

[0099] When the length of the curved portion (bend length) is 0.175 mm or greater, contact pressure actually decreases as the bend angle of the curved portion increases. This length corresponds to 31.8% or greater of the liner thickness of 0.55 mm. In other words, sealing with an additional curved portion was found to be counterproductive. This is because the curved portion creates a dead zone between the liner and the cylindrical can, which reduces contact pressure. Furthermore, the curved portion causes significant plastic deformation of the liner, thereby reducing contact pressure.

[0100] Therefore, it can be seen that, contrary to common predictions, the contact pressure (sealing degree) decreases when secondary sealing is performed by the curved portion. In order to enhance the seal by the curved portion, it is necessary to ensure that the curved portion does not form a dead zone between the liner and the cylindrical can, and to limit the size and bending angle of the curved portion to a range where the curved portion does not cause significant plastic deformation of the liner.

[0101] The crimping unit is usually constructed in two or more stages, and the upper portion of the cylindrical can is crimped by bending the upper portion in stages. Three clamping jaws clamp the cylindrical can based on the curled portion of the cylindrical can, and the end of the cylindrical can is bent and deformed by moving the crimping unit from top to bottom.

[0102] In the crimping apparatus according to the present invention, the crimping is normally performed in the same manner as in conventional crimping apparatuses. The crimping is performed step by step sequentially along a circular track by a cam-type apparatus. However, the crimping apparatus according to the present invention is characterized in that the final crimping unit is Figures 7 to 9 Shown in.

[0103] Figure 7 is an exploded perspective view of a crimping device according to the present invention, Figure 8 is a cross-sectional view of a crimping apparatus according to the present invention, and Figure 9 It is a partial enlarged view of the final crimping unit according to the present invention.

[0104] Reference Figures 7 to 9The cylindrical battery crimping device for crimping the upper portion of the cylindrical can of the cylindrical battery 100 to form a crimped portion configured to wrap around the outer periphery of the gasket includes: three clamping jaws 50 configured to fix the cylindrical side surface of the cylindrical can; at least one crimping unit configured to gradually crimp the cylindrical battery; and a final crimping unit 60 configured to finally crimp the cylindrical battery, wherein the length of the bent portion obtained by further bending the end of the crimped portion into the gasket by the final crimping unit 60 is less than 0.175 mm. The length of the bent portion corresponds to less than 31.8% of the thickness of the gasket.

[0105] exist Figure 8 , the cylindrical battery is omitted in order to illustrate the coupling state between the clamping jaws and the final crimping unit 60. Figure 9 The bottom four figures are enlarged views showing the portion actually crimped by the final crimping unit 60. Figure 9 and Figure 3 , Figure 9 The portion indicated by the dashed squares in the bottom four figures is in contact with the horizontal portion 26 of the crimping portion 21 of the cylindrical battery. This horizontal portion 26 is located at the uppermost end of the crimping portion and forms a horizontal plane. In actual crimping, horizontal portion 26 is bent by the crimping unit in the previous step, but maintains contact during the final crimping.

[0106] exist Figure 9 , the portion indicated by the dotted circle is a portion for crimping the bent portion 25 provided at the end of the horizontal portion 26. The length of the bent portion 25 is 0.175 mm, which corresponds to less than 31.8% of the gasket thickness. Figure 9 The final crimping unit 60 only bends the cylindrical can 20 without performing separate cutting, so Figure 9 The length of the inclined surface of the circled portion must not be excessively greater than the length of the curved portion 25, ie, 0.175 mm. Since the curved portion 25 may contact the pad 40 and may be inserted into the pad 40, Figure 9 The length of the inclined surface of the circled portion must be smaller than or close to the length of the bent portion 25. This is because if the length of the inclined surface of the final crimping unit 60 is too large, the gasket may be damaged.

[0107] Since the bending angle of the bent portion 25 is from 15 degrees downward from the horizontal to 90 degrees at right angles to the horizontal, Figure 9 The angle of the inclined surface in the circled portion must also be from 15 degrees downward from the horizontal to 90 degrees at right angles to the horizontal. Figure 9 The lower end is a schematic diagram of the bending angle in each case.

[0108] That is, the final crimping unit according to the present invention includes a horizontal crimping portion in contact with the horizontal portion 26 and a bent portion configured to crimp the bent portion 25, wherein the length of the bent portion is less than or similar to the length of the bent portion 25, preferably less than or equal to the length of the bent portion 25, and the angle formed by the horizontal crimping portion and the bent portion is 15 degrees to 90 degrees, that is, a right angle.

[0109] Those skilled in the art to which the present invention pertains will appreciate that, based on the above description, various applications and modifications are possible within the scope of the present invention.

[0110] Description of Reference Signs

[0111] 10: Electrode assembly

[0112] 11: Electrode plate

[0113] 12: Separator

[0114] 13: First lead

[0115] 20: Cylindrical tank

[0116] 21: Crimping part

[0117] 24: Curling part

[0118] 25: curved part

[0119] 25D: Bending angle of the curved part

[0120] 26: Horizontal section

[0121] 30: Cover assembly

[0122] 34: PTC components

[0123] 36: Safety vents

[0124] 38: Current interruption device

[0125] 40: Padding

[0126] 42: Auxiliary pad

[0127] 50: Gripper

[0128] 60: Final crimping unit

[0129] 100: Cylindrical battery.

Claims

1. A cylindrical battery comprising: a cylindrical can configured to receive the electrode assembly; a cap assembly mounted to the opening of the cylindrical can; as well as a gasket interposed between the cylindrical can and the cap assembly, wherein The cylindrical can is provided with a press-fitting portion at an upper portion of the cylindrical can, the press-fitting portion being configured to wrap an outer circumference of the gasket, The crimping portion is provided at a distal end thereof with a bent portion further bent into the pad, and The length of the bent portion is less than 0.175 mm.

2. The cylindrical battery according to claim 1, wherein The length of the bent portion is 0.15 mm or less.

3. The cylindrical battery according to claim 1, wherein The bending angle of the bent portion ranges from 15 degrees downward from the horizontal to 90 degrees at right angles to the horizontal.

4. The cylindrical battery according to claim 1, wherein The crimping portion includes a horizontal portion provided at an uppermost end portion of the crimping portion, the horizontal portion forming a horizontal plane, and The curved portion is provided at a terminal end of the horizontal portion.

5. The cylindrical battery according to claim 4, wherein: The length of the horizontal portion is 0.9 mm or greater.

6. The cylindrical battery according to claim 1, wherein The thickness of the cylindrical can is 0.3 mm or more.

7. A method for sealing a cylindrical battery, the cylindrical battery comprising: a cylindrical can configured to receive the electrode assembly; a cap assembly mounted to the opening of the cylindrical can; as well as a gasket interposed between the cylindrical can and the lid assembly, The sealing method comprises: a step of bending an upper portion of the cylindrical can to form a crimped portion configured to wrap an outer peripheral edge of the liner; and The step of further bending the end of the crimping portion into the pad to form a bent portion, wherein The length of the bent portion is less than 0.175 mm.

8. The method for sealing a cylindrical battery according to claim 7, wherein: The length of the bent portion is 0.15 mm or less.

9. The method for sealing a cylindrical battery according to claim 7, wherein: The bending angle of the bent portion ranges from 15 degrees downward from the horizontal to 90 degrees at right angles to the horizontal.

10. The method for sealing a cylindrical battery according to claim 7, wherein The crimping portion includes a horizontal portion provided at an uppermost end portion of the crimping portion, the horizontal portion forming a horizontal plane, and The curved portion is provided at a terminal end of the horizontal portion.

11. The method for sealing a cylindrical battery according to claim 7, wherein: The length of the horizontal portion is 0.9 mm or greater.

12. A cylindrical battery crimping device for crimping an upper portion of a cylindrical can of the cylindrical battery to form a crimped portion, the crimped portion being configured to wrap around an outer periphery of a gasket, the crimping device comprising: three clamping jaws configured to secure the cylindrical side surface of the cylindrical can; at least one pressing unit configured to press the cylindrical battery step by step; as well as A final pressing unit is configured to perform final pressing on the cylindrical battery, wherein: The length of the bent portion obtained by further bending the end of the crimped portion into the gasket by the final crimping unit is less than 0.175 mm.

13. The cylindrical battery crimping device according to claim 12, wherein: The length of the bent portion is 0.15 mm or less.

14. The cylindrical battery crimping device according to claim 12, wherein: The bending angle of the bent portion ranges from 15 degrees downward from the horizontal to 90 degrees at right angles to the horizontal.

15. The cylindrical battery crimping device according to claim 12, wherein: The crimping portion includes a horizontal portion provided at an uppermost end portion of the crimping portion, the horizontal portion forming a horizontal plane, and The curved portion is provided at a terminal end of the horizontal portion.

16. The cylindrical battery crimping device according to claim 12, wherein: The length of the horizontal portion is 0.9 mm or greater.

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