Cylindrical battery with enhanced sealing

Abstract

The present invention relates to: a cylindrical battery comprising a cylindrical can accommodating 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, wherein the upper portion of the cylindrical can is provided with a crimping portion that wraps around the outer periphery of the gasket, a bending portion that is bent further into the gasket is provided at the end of the crimping portion, and the length of the bending portion is less than 0.175 mm; a sealing method of the cylindrical battery; and a crimping device of the cylindrical battery. The present invention solves the problem of sealing degradation that occurs in primary crimping applying primary pressure and secondary crimping applying secondary pressure in the sealing of the cylindrical battery by the crimping portion. Accordingly, the sealing of the cylindrical battery according to the present invention is further enhanced by secondary sealing.

Description

Cylindrical battery with reinforced sealing

[0001] The present invention relates to a cylindrical battery with reinforced sealing. Specifically, it relates to a cylindrical battery with reinforced crimping sealing, a sealing method for the cylindrical battery, and a crimping device for the cylindrical battery.

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

[0003] Figures 1 and 2 are two examples of cross-sectional views illustrating a typical cylindrical battery. Figures 1 and 2 illustrate a cylindrical battery including an electrode assembly including a positive electrode, a negative electrode, and a separator. The battery includes a cylindrical can including a top opening, a cap assembly coupled to the cylindrical can by a crimping portion formed on an upper outer surface of the cylindrical can and formed by bending a portion of the top opening inward, and a gasket interposed between the cylindrical can and the cap assembly.

[0004] A crimping portion is formed on the upper end of a cylindrical can so that the cap assembly can be mounted on the open end of the cylindrical can. More specifically, the crimping portion is formed by forming an indentation inward by beading the upper end of the cylindrical can, inserting a gasket into the open end, sequentially inserting the outer surfaces of a top cap, a PTC element, and a safety vent, and then bending the upper end of the cylindrical can inward. As a result, the gasket located on the inner surface of the crimping portion is formed to surround the gasket, and the cap assembly is mounted by performing a crimping and pressing process.

[0005] The crimping portion is structured so that the end is bent inward so that the cap assembly can be stably mounted on the open top of the cylindrical can while the gasket is inserted. The side walls of the crimping portion are formed vertically, identical to the side surfaces of the battery.

[0006] The material of the cylindrical can is not particularly limited and may be formed from stainless steel, steel, aluminum, or any of their equivalents. Because cylindrical cans must be conductive, they utilize metal components, which can be susceptible to corrosion when exposed to moisture from the outside.

[0007] Referring to FIG. 1, a cylindrical battery (100) includes a cylindrical can (20) that houses an electrode assembly (10) together with an electrolyte, a cap assembly (30) that is sealingly connected to an open end of the cylindrical can (20), and a gasket (40) interposed between the cylindrical can (20) and the cap assembly (30).

[0008] The cap assembly (30) may be a top cap that seals the open end of the cylindrical can (20), one side of which is bent and arranged to contact all of the side, upper and lower surfaces of the top cap, and the other side of which is bent and arranged to contact the inner surface of the gasket (40), and may be a safety vent (36) electrically connected to the electrode assembly (10).

[0009] A battery equipped with such a cap assembly (30) can provide high output momentarily when used as a power source for a power tool such as an electric drill and can be stable even against external physical shocks such as vibration and dropping.

[0010] The cap assembly (30) in which the safety vent (36) is bent to wrap around the top cap can form one or more connection portions at the contact surfaces of the safety vent (36) and the top cap, and the connection portions are formed by welding or the like. The term "welding" used in the present invention is used as a concept that includes not only welding in the literal sense such as laser welding, ultrasonic welding, resistance welding, etc., but also fastening methods such as soldering. Welding may be performed during the assembly process of the cap assembly (30) itself, or may be performed when the cap assembly (30) is installed on the cylindrical can (20).

[0011] The safety vent (36) serves to cut off current or exhaust gas when pressure inside the battery rises, and is preferably made of metal. The thickness of the safety vent (36) may vary depending on the material and structure, and is not particularly limited as long as it can rupture and exhaust gas when a certain high pressure is generated inside the battery. For example, it may be 0.2 to 0.6 mm.

[0012] The thickness of the top cap portion in contact with the safety vent (36) is not particularly limited as long as it can protect various components of the cap assembly (30) from external pressure, and may be, for example, 0.3 to 0.5 mm. If the thickness of the top cap portion is too thin, it is difficult to exhibit mechanical rigidity, and conversely, if it is too thick, the capacity of the battery may be reduced compared to the same specification due to an increase in size and weight, which is not desirable.

[0013] The above gasket (40) has a cylindrical shape with both ends open overall, and it is preferable that one end facing the inner surface of the cylindrical can (20) is bent at a right angle toward the center so as to be placed on the open portion, i.e., the crimping portion, of the cylindrical can (20). The other end of the gasket (40) is initially straightened and faces the axial direction of the cylindrical gasket (40), and during the pressurizing process with the cylindrical can (20), it is bent at a right angle toward the center so that the inner and outer circumferential surfaces are folded in a state in which they are in close contact with the top cap of the cap assembly (30) and the inner surface of the cylindrical can (20), respectively.

[0014] The above gasket (40) is composed of an elastic polymer resin with electrical insulation properties, and the polymer resin must have electrical insulation properties, impact resistance, elasticity, and durability. In general, the gasket has insulating properties, must have excellent chemical resistance to the electrolyte to prevent leakage of the electrolyte, and must also have heat resistance to maintain the gasket's airtightness under the harsh conditions of high temperature and high humidity inside the battery. The gasket is generally made of polypropylene, but is not limited thereto. In addition, the gasket (40) may include a vaporizable rust inhibitor.

[0015] The electrode assembly (10) comprises two electrode plates (11) having different polarities and having a wide roll-shaped plate shape, and a separator (12) interposed between the electrode plates (11) or positioned on the left or right side of one of the electrode plates (11) to mutually insulate the electrode plates (11), and is preferably structured in a so-called 'jelly roll' shape. Of course, it may also be structured in which positive and negative electrode plates of a predetermined specification are laminated with the separator (12) interposed between them.

[0016] The two electrode plates (11) each have a structure in which an active material slurry is applied to a current collector in the form of a metal foil or metal mesh containing aluminum and copper. The slurry is typically formed by stirring a granular active material, an auxiliary conductor, a binder, a plasticizer, etc. in a state in which a solvent is added. The solvent is removed in a subsequent process. Non-coated portions, where the slurry is not applied, may exist at the beginning and end of the current collector in the direction in which the electrode plates (11) are wound. A pair of leads corresponding to each electrode plate (11) are attached to the non-coated portions. The first lead (13) attached to the upper end of the electrode assembly (10) is electrically connected to the cap assembly (30), and the 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 may be drawn out in the direction of the cap assembly (30). The electrode assembly (10) is preferably placed on a first insulating plate (not shown) installed on the bottom of a cylindrical can (20), and a second insulating plate (not shown) is preferably placed on the top of the electrode assembly (10). The first insulating plate insulates between the electrode assembly (10) and the bottom of the cylindrical can (20), and the second insulating plate insulates between the electrode assembly (10) and the cap assembly (30).

[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 having an open top and a sealed bottom opposite thereto. An electrode assembly (10) and an electrolyte (not shown) are accommodated in the internal space of the cylindrical can (20). The electrolyte is for moving lithium ions generated by an electrochemical reaction of an electrode plate (11) during charging and discharging of a secondary battery (100). The electrolyte may be a non-aqueous organic electrolyte that is a mixture of a lithium salt and a high-purity organic solvent, or a polymer using a polymer electrolyte, but the type of the 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) to prevent the electrode assembly (10) wound in a jelly roll shape from unwinding and to serve as a passage for the movement of gas inside the secondary battery (100). A beading portion (24) formed by pressing and bending from the outside to the inside is provided at the upper part of the cylindrical can (20), that is, the upper part of the electrode assembly (10), to prevent the electrode assembly (10) from flowing upward and downward.

[0019] The cap assembly (30) is assembled to the opening of a cylindrical can (20) in a sealed state by interposing a gasket (40), and includes a top cap and a safety vent (36). The top cap has an electrode terminal (not shown) formed to be electrically connected to the outside. The safety vent (36) is formed in a form that is bent and wraps around the outer surface of the top cap.

[0020] The cylindrical battery (100) may further include a current interrupting device welded to the lower end of the safety vent (36) and having a lower end that can be connected to the electrode assembly (10). Specifically, the safety vent (36) is welded to a current interrupting device (CID: current interrupt device) (38) that protrudes convexly in the center, and the current interrupting device (38) can be deformed 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 interrupting element (38) and is configured to surround the outer surface of the current interrupting element (38). In particular, the auxiliary gasket (42) contacts the upper and side surfaces of the outer surface of the current interrupting element (38) to support the upper and side surfaces of the current interrupting element (38). In addition, the auxiliary gasket (42) serves to electrically insulate the current interrupting element (38) and the safety vent (36) from each other except for the portion where the protruding portion of the safety vent (36) and the current interrupting element (38) come into contact.

[0022] The positive lead welded to the positive foil of the jelly-roll type electrode assembly (10) is electrically connected to the cap assembly (30) and connected to the protruding terminal on the top of the top cap, and the negative lead welded to the negative foil is welded to the sealed end of the cylindrical can (20) so that the cylindrical can (20) itself forms the negative terminal. The material of the cylindrical can (20) is not particularly limited and may be formed of any one of stainless steel, steel, aluminum, or an equivalent thereof. When the electrode assembly (10) is housed in the cylindrical can (20), an electrolyte is injected, and the cap assembly (30) is mounted on the open end of the cylindrical can (20) to seal it, the assembly of the secondary battery is completed.

[0023] The secondary battery may be a lithium (ion) secondary battery having high energy density, discharge voltage, and high output stability. The lithium secondary battery is composed of a positive electrode, a negative electrode, a separator (12), a non-aqueous electrolyte containing a lithium salt, etc. The positive electrode is manufactured, for example, by coating a mixture of a positive electrode active material, a conductive material, and a binder on a positive electrode current collector and drying it, and if necessary, a filler may be further added. The negative electrode is manufactured by coating a negative electrode active material on a negative electrode current collector and drying it, and if necessary, the above-mentioned components may be further included. The separator (12) is interposed between the negative electrode and the positive electrode, and a thin insulating film having high ion permeability and mechanical strength is used. The non-aqueous electrolyte containing a lithium salt is composed of a non-aqueous electrolyte and a lithium salt, and the non-aqueous electrolyte may be a liquid non-aqueous electrolyte, a solid electrolyte, an inorganic solid electrolyte, etc. Here, the current collector, electrode active material, conductive material, binder, filler, separator (12), electrolyte, lithium salt, etc. are widely known in the art, so a detailed description thereof is omitted.

[0024] Fig. 2 is another example of a cross-sectional view illustrating a typical cylindrical battery. Among the drawing symbols described in Fig. 2, the same components as the reference symbols described in Fig. 1 are the same members having the same function. Referring to Fig. 2, the cap assembly (30) may include a top cap that seals the open end of the cylindrical can (20) and is positioned to contact a protrusion of the gasket (40), a PTC element (positive temperature coefficient) (34) positioned to contact the top cap, and a safety vent (36) positioned such that one surface contacts the PTC element (34) and a portion of the other surface contacts the gasket (40). The gasket (40) is the same as the gasket used in Fig. 1.

[0025] The above PTC element (34) blocks current by significantly increasing battery resistance when the temperature inside the battery rises, and the thickness of the PTC element (34) may also vary depending on the material and structure, and may be, for example, 0.2 mm to 0.4 mm. If the thickness of the PTC element (34) is thicker than 0.4 mm, the internal resistance increases, and the size of the battery may increase, which may reduce the capacity of the battery compared to the same specification. Conversely, if the thickness of the PTC element (34) is thinner than 0.2 mm, it may be difficult to exhibit the desired current blocking effect at high temperatures and may be destroyed by even a weak external impact. Therefore, the thickness of the PTC element (34) may be appropriately determined within the above thickness range by comprehensively considering these points.

[0026] The thickness of the top cap portion that comes into contact with the PTC element (34) is not particularly limited as long as it can protect various components of the cap assembly (30) from externally applied pressure, and may be, for example, 0.3 to 0.5 mm. If the thickness of the top cap portion is too thin, it is difficult to exhibit mechanical rigidity, and conversely, if it is too thick, the capacity of the battery may be reduced compared to the same specification due to an increase in size and weight, which is not desirable.

[0027] A secondary battery including a top cap, a PTC element (34), and a cap assembly (30) with a safety vent can be used as a power source for a mobile phone, laptop, etc., which stably provides a constant output.

[0028] The present invention relates to a cylindrical battery with reinforced sealing, and more specifically, to a cylindrical battery with reinforced crimping portion sealing. The following description schematically illustrates components related to the crimping portion sealing, namely, a crimping portion, a beading portion, a gasket, a cylindrical can, and a cap assembly.

[0029] Cylindrical batteries have an open end and are sealed by a crimping portion formed at the open end. Cylindrical batteries are sealed by mechanical compression, and this mechanical compression sealing can operate as a leakage path if a minute gap occurs between the two interfaces. As a result, cylindrical batteries have a disadvantage in that their sealing properties are not as good as those of pouch-type batteries. When cylindrical batteries are used as power sources for electric vehicles, hybrid vehicles, etc., a long lifespan is required, and a large number of battery cells are densely packed, so the sealing properties of such batteries are very important.

[0030] Much research is being conducted on sealing can-shaped batteries containing cylindrical batteries.

[0031] Patent Document 1 describes a configuration in which an O-shaped positive electrode ring is inserted into the space formed between a gasket and a sealed can to fill the space, and Patent Document 2 describes a configuration in which the airtightness of the internal space between the gasket and the can is improved through a sealing film. Patent Document 3 describes a configuration in which the sealing performance is improved and electrical insulation is formed by filling the space between the gasket and the can, and between the can and the positive electrode plate, through a sealant and a binder.

[0032] The anode ring and sealing film of Patent Documents 1 and 2 only serve to seal the space between the gasket and the sealed can, and do not specify the basic characteristics of a washer, such as electrical insulation and corrosion prevention, so it does not appear that the anode ring is used as a washer. The sealant and binder of Patent Document 3 are not a type of component, but a type of substance that fills the space between the gasket and the can, or the can and the anode plate. Even if they have the functions of insulation and sealing, they cannot be considered washers. In addition, the configuration of injecting the sealant and binder of Patent Document 3 is simply for sealing and insulation, and it is difficult to view them as a washer between the gasket and the can to fill the microscopic gaps in the internal space through electrolyte absorption.

[0033] Patent Document 4 prevents leakage of electrolyte by suppressing the sealing portion from opening when subjected to external physical impacts such as vibration or dropping and when internal pressure increases by continuously bending the upper part of the crimping portion of a cylindrical can twice under predetermined conditions, and minimizes deformation such as wrinkles formed on the can when bent with a small radius of curvature.

[0034] Patent Document 5 relates to a cylindrical battery, which includes a first crimping mold that applies a first pressure so that an end of an upper opening portion forms a slope inclined toward the central axis of a metal can in a vertical cross-section, and a second crimping mold that applies a second pressure to the end of the upper opening portion where the slope is formed so that a flat section parallel to the lower surface of the metal can is formed in the crimping portion, and a flat section corresponding to the flat section is formed on the lower surface of the second crimping mold facing the end of the upper opening portion so as to form a flat section in the crimping portion.

[0035] Patent Document 4 aims to strengthen the seal, but fails to recognize that unusual phenomena may arise due to bending at the crimping area. Patent Document 5 simply aims to create a flat section at the crimping area to facilitate welding, and does not offer a solution for strengthening the seal.

[0036] In particular, the inventor of the present invention observed an abnormal phenomenon in which the sealing (pressure) actually decreased when additional crimping was performed two or more times in addition to the first crimping, but the prior art not only did not recognize this but also did not present a solution to this.

[0037] In relation to the above configuration, the characteristic of the pressing force of the crimping part changing from + to 0 or - depending on the bending length or angle was observed through simulation results. While it is generally recognized that the pressing force increases when the bending part is provided, the simulation results observed a negative effect in which the pressing force actually decreases beyond a certain length, which is not something that a person skilled in the art would easily predict.

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

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

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

[0041] Republic of Korea Patent Publication No. 2008-0053538 (Patent Document 4)

[0042] Republic of Korea Patent Publication No. 2018-0072990 (Patent Document 5)

[0043] The present invention is intended to solve the above-mentioned problem, and provides a cylindrical battery having reinforced sealing of a crimping portion and a method for reinforcing the sealing of a crimping portion of a cylindrical battery by solving the problem of sealing degradation occurring in the first crimping by applying the first pressure and the second crimping by applying the second pressure in sealing by a crimping portion of a cylindrical battery.

[0044] The secondary crimping mentioned here refers to additional crimping performed after the primary crimping. More specifically, it refers to the process of processing the final bend of the crimped section.

[0045] To achieve this purpose, the present invention comprises a cylindrical battery including a cylindrical can containing an electrode assembly, a cap assembly mounted on an opening of the cylindrical can, and a gasket interposed between the cylindrical can and the cap assembly.

[0046] The cylindrical can is provided with a cylindrical battery in which the upper part is provided with a crimping portion that wraps around the outer periphery of the gasket, and a bending portion is provided at the end of the crimping portion that is further bent into the inside of the gasket, and the length of the bending portion is less than 0.175 mm. The length of the bending portion corresponds to a case where it is less than 31.8% of the thickness of the gasket.

[0047] The length of the above-mentioned bending portion may be 0.15 mm or less. The length of the above-mentioned bending portion corresponds to 27.2% or less of the gasket thickness.

[0048] The angle at which the above-mentioned bending portion is bent may be 15 degrees or more downward from the horizontal or 90 degrees or less at a right angle.

[0049] The above gasket may comprise polybutylene terephthalate (PBT).

[0050] The above crimping portion may include a horizontal portion forming a horizontal plane at the top, and the bending portion may be provided at an end of the horizontal portion.

[0051] The length of the above horizontal portion may be 0.9 mm or more.

[0052] The thickness of the above cylindrical can may be 0.3 mm or more.

[0053] The present invention also relates to a sealing method for a cylindrical battery, comprising a cylindrical can containing an electrode assembly, a cap assembly mounted on an opening of the cylindrical can, and a gasket interposed between the cylindrical can and the cap assembly.

[0054] A method for sealing a cylindrical battery is provided, comprising: a step of forming a crimping portion that wraps around the outer periphery of the gasket by bending the upper portion of the cylindrical can; and a step of further bending the end of the crimping portion into the inside of the gasket to form a bending portion, wherein the length of the bending portion is less than 0.175 mm. The length of the bending portion corresponds to a case where it is less than 31.8% of the thickness of the gasket.

[0055] Additionally, the length of the above-mentioned bending portion may be 0.15 mm or less. The length of the above-mentioned bending portion corresponds to 27.2% or less of the thickness of the gasket.

[0056] The angle at which the above-mentioned bending portion is bent may be 15 degrees or more downward from the horizontal or 90 degrees or less at a right angle.

[0057] The above gasket may comprise polybutylene terephthalate (PBT).

[0058] The above crimping portion may include a horizontal portion forming a horizontal plane at the top, and the bending portion may be provided at an end of the horizontal portion.

[0059] The length of the above horizontal portion may be 0.9 mm or more.

[0060] The thickness of the above cylindrical can may be 0.3 mm or more.

[0061] The present invention also provides a battery pack including the cylindrical battery.

[0062] The present invention also provides a crimping device for a cylindrical battery, which forms a crimping portion that wraps around the outer periphery of a gasket by processing the upper portion of a cylindrical can of a cylindrical battery, comprising three jaws that secure a cylindrical side of the cylindrical can, at least one crimping portion that crimps the cylindrical battery in stages, and a final crimping portion that finally crimps the cylindrical battery, wherein the length of the bending portion that further bends the end of the crimping portion into the inside of the gasket is less than 0.175 mm. The length of the bending portion corresponds to a case where it is less than 31.8% of the thickness of the gasket.

[0063] The length of the above-mentioned bending portion may be 0.15 mm or less. The length of the above-mentioned bending portion corresponds to 27.2% or less of the gasket thickness.

[0064] The angle at which the above-mentioned bending portion is bent may be 15 degrees or more downward from the horizontal or 90 degrees or less at a right angle.

[0065] The above crimping portion may include a horizontal portion forming a horizontal plane at the top, and the bending portion may be provided at an end of the horizontal portion.

[0066] The length of the above horizontal portion may be 0.9 mm or more.

[0067] The thickness of the above cylindrical can may be 0.3 mm or more.

[0068] The present invention can also be provided in a configuration in which the problems to be solved are arbitrarily combined.

[0069] As described above, the present invention provides a cylindrical battery including a cylindrical can containing an electrode assembly, a cap assembly mounted on an opening of the cylindrical can, and a gasket interposed between the cylindrical can and the cap assembly, wherein the upper portion of the cylindrical can is provided with a crimping portion that wraps around the outer periphery of the gasket, and a bending portion is provided at an end of the crimping portion that is further bent into the inside of the gasket, and a length of the bending portion is less than 0.175 mm.

[0070] The present invention also provides a sealing method for a cylindrical battery, comprising a cylindrical can containing an electrode assembly, a cap assembly mounted on an opening of the cylindrical can, and a gasket interposed between the cylindrical can and the cap assembly, the method comprising the steps of: forming a crimping portion that wraps around the outer periphery of the gasket by bending the upper portion of the cylindrical can; and further bending an end of the crimping portion into the inside of the gasket to form a bent portion, wherein the length of the bent portion is less than 0.175 mm.

[0071] The present invention also provides a crimping device for a cylindrical battery, which forms a crimping portion that wraps around the outer periphery of a gasket by processing the upper portion of a cylindrical can of a cylindrical battery, comprising three jaws that secure a cylindrical side of the cylindrical can, one or more crimping portions that stepwise crimp the cylindrical battery, and a final crimping portion that finally crimps the cylindrical battery, wherein the length of the bending portion that further bends the end of the crimping portion into the inside of the gasket is less than 0.175 mm.

[0072] Through this, the problem of sealing degradation occurring during the first crimping by applying the first pressure and the second crimping by applying the second pressure in sealing by the crimping section of the cylindrical battery was solved. The cylindrical battery according to the present invention has the characteristic of further strengthening the sealing by the second sealing.

[0073] Figure 1 is an example of a cross-sectional view illustrating a cylindrical battery.

[0074] Figure 2 is another example of a cross-sectional view showing a cylindrical battery.

[0075] Figure 3 is a schematic diagram of a crimping part according to the present invention.

[0076] Figure 4 is an example of a calculation method for conducting a simulation according to the present invention.

[0077] Figure 5 is another example of a calculation method for conducting a simulation according to the present invention.

[0078] Figure 6 is a simulation result according to the present invention.

[0079] Figure 7 is an exploded perspective view of a creeping device according to the present invention.

[0080] Figure 8 is a cross-sectional view of a creeping device according to the present invention.

[0081] Figure 9 is a partially enlarged view of the final creeping processing section according to the present invention.

[0082] Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail, so that those with ordinary skill in the art can easily implement the present invention. However, when describing the operating principles of preferred embodiments of the present invention in detail, if a detailed description of a related known function or configuration is judged to unnecessarily obscure the gist of the present invention, such detailed description will be omitted.

[0083] Additionally, the same drawing reference numerals are used for parts with similar functions and actions throughout the drawings. Throughout the specification, when a part is said to be connected to another part, this includes not only direct connections but also indirect connections with other elements intervening. Furthermore, inclusion of a component does not exclude other components unless specifically stated otherwise, but rather implies the inclusion of additional components.

[0084] Fig. 3 is a schematic diagram of a crimping part according to the present invention. Fig. 3 is a simple schematic diagram of the crimping part for simulation. The cylindrical battery is provided with a beading part (24), and the gasket (40) is primarily sealed by the crimping part (21), and the cap assembly (30) is also sealed by the gasket (40). The crimping part (21) includes a horizontal part (26) forming a horizontal plane at the top, and a bending part (25) is provided at the end of the horizontal part (26). The length of the bending part (25) and the angle (25D) at which the bending part is bent are variables used in the simulation.

[0085] Table 1 is a list of sets for which simulations were conducted in embodiments according to the present invention.

[0086]

[0087] The simulation was conducted using the following interpretation method.

[0088] Secondary crimping was simulated through interference fit analysis. Third crimping was simulated by applying hinge (corner) and boundary conditions to the bending part of a cylindrical can. The contact pressure of the gasket (PBT) according to the angle of the bending part was calculated. The gasket used in the simulation had a thickness of 0.55 mm and was made of PBT. The PBT properties were calculated by dividing it into elastic and plastic regions. When the plastic stress is less than 42 MPa, it is considered as an elastic region, and the stress is calculated by multiplying the elastic modulus of 1567 by the elongation. For the plastic region, the plastic stress-plastic strain curve was used.

[0089] The length of the horizontal section was calculated based on a minimum of 0.9 mm. The material of the cylindrical can was nickel-plated steel, and the thickness of the crimping area was considered to be 0.3 mm.

[0090] Figure 4 is an example of a calculation method for performing a simulation according to the present invention, and Figure 5 is another example of a calculation method for performing a simulation according to the present invention.

[0091] Referring to FIGS. 4 and 5, the red-marked portion on the left side of FIGS. 4 and 5 is the portion where the contact pressure was calculated. FIGS. 4 and 5 show the pressure inside and outside the gasket for one case. The upper left of the portion marked in red, that is, the starting point of the U-shape, was designated as 0, and the contact pressure corresponding to each portion was calculated by moving along it. The calculation result according to one example is shown on the right side of FIGS. 4 and 5. The contact pressure in the graph on the right is integrated along the length to calculate the contact pressure for each portion, and all cases in FIGS. 4 and 5 are combined to derive the total contact pressure for one case. The portions marked in red in FIGS. 4 and 5 are areas where sealing actually occurs by the gasket, and the contact pressure in all of these portions was calculated to determine the pressure generated by the overall sealing.

[0092] Figure 6 is a simulation result according to the present invention.

[0093] Referring to Fig. 6, when the bending length (Bending) of the bending portion is 0.15 mm or less, the contact pressure increases as the bending angle of the bending portion increases. In other words, it appears that sealing by an additional bending portion is effective only when the bending portion length is 0.15 mm or less, and it was found to have the opposite effect when it exceeds 0.15 mm. This corresponds to a case where the gasket thickness is 27.3% or less when compared to a gasket thickness of 0.55 mm.

[0094] When the bending length (Bending) of the bending part exceeds 0.175mm, the contact pressure actually decreases as the bending angle of the bending part increases. This corresponds to a case where the bending angle is 31.8% or more of the gasket thickness compared to a gasket thickness of 0.55mm. In other words, it was found that sealing by an additional bending part actually has the opposite effect. This is interpreted as a dead space created between the gasket and the cylindrical can by the bending part, which reduces the contact pressure. In addition, it is interpreted as a large plastic deformation of the gasket caused by the bending part, which reduces the contact pressure.

[0095] In this way, when performing secondary sealing through the bend, it can be observed that, contrary to conventional expectations, the contact pressure (sealing degree) actually decreases. In order to strengthen the seal through the bend, the bend should not create a dead space between the gasket and the cylindrical can, and the size and angle of the bend should be limited so that the gasket does not significantly deform plastically due to the bend.

[0096] The crimping process usually consists of two or more stages, and the upper part of a cylindrical can is crimped by gradually bending it. Three groups fix the cylindrical can based on the beading part of the cylindrical can, and the end of the cylindrical can is bent and deformed by the crimping process that descends from the upper part.

[0097] In the crimping device according to the present invention, the crimping process that is typically performed is identical to that of conventional crimping devices. The step-by-step crimping process is sequentially performed along a circular orbit by a cam-type device. However, the crimping device according to the present invention has a unique feature in the final crimping process section, and Figures 7 to 9 illustrate only this section.

[0098] Fig. 7 is an exploded perspective view of a crimping device according to the present invention, Fig. 8 is a cross-sectional view of a crimping device according to the present invention, and Fig. 9 is a partially enlarged view of a final crimping processing section according to the present invention.

[0099] Referring to FIGS. 7 to 9, a crimping device for a cylindrical battery (100) is provided, which forms a crimping portion that wraps around the outer periphery of a gasket by processing the upper portion of a cylindrical can, including three jaws (50) that fix a cylindrical side of the cylindrical can, one or more crimping portions that stepwise crimp the cylindrical battery, and a final crimping portion (60) that finally crimps the cylindrical battery, wherein the length of the bending portion that further bends the end of the crimping portion into the inside of the gasket is less than 0.175 mm. The length of the bending portion corresponds to a case where it is less than 31.8% of the thickness of the gasket.

[0100] In order to show the state of the connection between the cylindrical battery and the final crimping processing section (60), the cylindrical battery is omitted in Fig. 8. The four lower drawings of Fig. 9 are enlarged views of the portion where actual crimping occurs in the final crimping processing section (60). Referring to Fig. 9 and Fig. 3, the portion indicated by the dotted square in the four lower drawings of Fig. 9 is the portion that contacts the horizontal portion (26) that forms the horizontal plane at the top of the crimping section (21) of the cylindrical battery. In actual processing, the horizontal portion (26) is already bent by the crimping processing section in the previous stage, but it also contacts it in the final crimping processing.

[0101] In Fig. 9, the part indicated by the dotted circle is the part for processing the bending part (25) provided at the end of the horizontal part (26). The length of the bending part (25) is 0.175 mm, which corresponds to a case where it is less than 31.8% of the gasket thickness. Since the final crimping processing part (60) according to Fig. 9 only bends the cylindrical can (20) without performing separate cutting, the length of the inclined surface among the parts indicated by the circle in Fig. 9 should not be excessively longer than the length of the bending part (25), which is 0.175 mm. Since the bending part (25) can be inserted into the gasket (40) by coming into contact with it, the length of the inclined surface among the parts indicated by the circle in Fig. 9 should be shorter than or similar to the length of the bending part (25). This is because if the length of the inclined surface of the final crimping processing part (60) becomes excessively long, the gasket may be damaged.

[0102] The angle at which the bending portion (25) is bent is 15 degrees or more downward from the horizontal and 90 degrees or less at a right angle, so the angle of the inclined surface among the parts indicated by a circle in Fig. 9 must also be 15 degrees or more and 90 degrees or less at a right angle. The lower part of Fig. 9 schematically illustrates each case separately.

[0103] That is, the final crimping processing section according to the present invention includes a horizontal processing section that comes into contact with the horizontal section (26), and a bending processing section for processing the bending section (25). The length of the bending processing section should be shorter than or similar to the length of the bending section (25), and preferably, it is less than or equal to the length of the bending section (25), and the angle formed by the horizontal processing section and the bending processing section is 15 degrees or more and 90 degrees or less, which is a right angle.

[0104] Anyone with ordinary knowledge in the field to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

[0105] (Explanation of symbols)

[0106] 10: Electrode assembly

[0107] 11: Electrode plate

[0108] 12: Membrane

[0109] 13: First Lead

[0110] 20: Cylindrical can

[0111] 21: Crimping section

[0112] 24: Bidding Department

[0113] 25: Bend section

[0114] 25D: Bending angle of the bending part

[0115] 26: Horizontal section

[0116] 30: Cap assembly

[0117] 34: PTC element

[0118] 36: Safety vent

[0119] 38: Current breaker

[0120] 40: Gasket

[0121] 42: Auxiliary gasket

[0122] 50: Jaw

[0123] 60: Final crimping processing section

[0124] 100: Cylindrical battery

Claims

1. A cylindrical can containing an electrode assembly; A cap assembly mounted on the opening of the cylindrical can; and A gasket interposed between the cylindrical can and the cap assembly; In a cylindrical battery including: The upper part of the above cylindrical can is provided with a crimping portion that wraps around the outer periphery of the above gasket, At the end of the above crimping portion, a bending portion is provided that is further bent into the inside of the gasket, A cylindrical battery having a length of the above-mentioned bending portion of less than 0.175 mm.

2. In paragraph 1, A cylindrical battery having a length of the above-mentioned bending portion of 0.15 mm or less.

3. In paragraph 1, A cylindrical battery in which the angle at which the above-mentioned bending portion is bent is 15 degrees or more downward from the horizontal and 90 degrees or less at a right angle.

4. In paragraph 1, The above crimping portion includes a horizontal portion forming a horizontal plane at the top, A cylindrical battery in which the above-mentioned bending portion is provided at the end of the above-mentioned horizontal portion.

5. In paragraph 4, A cylindrical battery having a length of the horizontal portion of 0.9 mm or more.

6. In paragraph 1, A cylindrical battery having a thickness of the above cylindrical can of 0.3 mm or more.

7. Cylindrical can containing the electrode assembly; A cap assembly mounted on the opening of the cylindrical can; and A gasket interposed between the cylindrical can and the cap assembly; In a sealing method of a cylindrical battery including: A step of forming a crimping portion that wraps around the outer periphery of the gasket by bending the upper portion of the cylindrical can; A step of further bending the end of the crimping portion into the inside of the gasket to form a bend portion; A sealing method for a cylindrical battery having a length of the above-mentioned bending portion of less than 0.175 mm.

8. In paragraph 7, A sealing method for a cylindrical battery having a length of the above-mentioned bending portion of 0.15 mm or less.

9. In paragraph 7, A sealing method for a cylindrical battery in which the angle at which the above-mentioned bending portion is bent is 15 degrees or more downward from the horizontal and 90 degrees or less at a right angle.

10. In paragraph 7, The above crimping portion includes a horizontal portion forming a horizontal plane at the top, A sealing method for a cylindrical battery in which the above-mentioned bending part is provided at the end of the above-mentioned horizontal part.

11. In paragraph 7, A sealing method for a cylindrical battery having a length of the horizontal portion of 0.9 mm or more.

12. In a crimping device for a cylindrical battery, the upper part of the cylindrical can is processed to form a crimping part that wraps around the outer periphery of the gasket. Three jaws for fixing the cylindrical sides of the cylindrical can; One or more crimping processing units for stepwise crimping the cylindrical battery; It includes a final crimping processing unit that finally crimps the cylindrical battery; A crimping device for a cylindrical battery, wherein the length of the bending portion that further bends the end of the crimping portion into the inside of the gasket is less than 0.175 mm.

13. In paragraph 12, A crimping device for a cylindrical battery having a length of the above-mentioned bending portion of 0.15 mm or less.

14. In paragraph 12, A crimping device for a cylindrical battery, wherein the angle at which the above-mentioned bending portion is bent is 15 degrees or more downward from the horizontal and 90 degrees or less at a right angle.

15. In paragraph 12, The above crimping portion includes a horizontal portion forming a horizontal plane at the top, The above-mentioned bending part is a crimping device for a cylindrical battery provided at the end of the above-mentioned horizontal part.

16. In paragraph 12, A crimping device for a cylindrical battery having a length of the horizontal portion of 0.9 mm or more.

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