Can for secondary battery and method for manufacturing can for secondary battery

Abstract

The present disclosure relates to a can for a secondary battery, and a technical problem to be solved is to provide a can having a reinforced corner portion. For this purpose, the can for a secondary battery of the present disclosure includes: a first surface including a long side extending in a first direction; a second surface opposite to the first surface and including a long side extending in the first direction; a third surface perpendicular to the first surface and in contact with the long side of the first surface and the long side of the second surface; and a fourth surface opposite to the third surface and in contact with the long side of the first surface and the long side of the second surface. The corner portion formed by the long side of the first surface and the fourth surface in contact with the long side of the first surface has a diagonal thickness greater than the thickness of the first surface and the fourth surface.

Description

Cans for secondary batteries and methods for manufacturing secondary battery cans

[0001] The present disclosure relates to a can for a secondary battery and a method for manufacturing the can for a secondary battery. Specifically, the present disclosure relates to a method for manufacturing a secondary battery-only can and a secondary battery can including a corner portion having a thick diagonal thickness.

[0002] Secondary batteries are rechargeable batteries capable of being charged and discharged multiple times. These batteries are primarily used in a variety of applications, including electronic devices (smartphones, laptops, tablets, etc.), electric vehicles, solar power generation, and emergency power supplies. Lithium-ion batteries, in particular, are used in various electronic devices and electric vehicles due to their high energy density and high charge-discharge efficiency.

[0003] Secondary batteries can be classified into cylindrical, prismatic, and pouch-type secondary batteries, depending on the shape of their housings. Prismatic secondary batteries have an electrode assembly housed within a prismatic metal can. The electrode assembly is inserted into the prismatic metal can, and a cap plate is welded to seal the can.

[0004] Among square metal cans, the length of side-terminal type cans is increasing as battery capacity increases. This decreases the rigidity of the can in the longitudinal direction, causing buckling. Buckling refers to the phenomenon in which a column suddenly bends when a compressive load is applied to both ends of the column when the length of the column is greater than the cross-sectional dimensions. Similarly, cans also bend when a load is applied when the length of the can is greater than the cross-sectional dimensions. To prevent this buckling phenomenon, the rigidity of the can needs to be increased.

[0005] The above-described information disclosed in the background technology of this invention is only intended to improve understanding of the background of the present invention, and therefore may include information that does not constitute prior art.

[0006] The problem to be solved by the present invention is to provide a can for a secondary battery, a secondary battery, and a method for manufacturing a secondary battery to solve the above-mentioned problems.

[0007] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0008] According to one embodiment of the present invention for solving the above technical problem, a can for a secondary battery includes a first surface including a long side extending in a first direction, a second surface opposite the first surface and including a long side extending in the first direction, a third surface perpendicular to the first surface and connected to the long side of the first surface and the long side of the second surface, and a fourth surface opposite the third surface and connected to the long side of the first surface and the long side of the second surface. A corner portion formed by the long side of the first surface and the fourth surface connected to the long side of the first surface has a diagonal thickness that is thicker than the thicknesses of the first surface and the fourth surface.

[0009] According to one embodiment of the present invention, the corner portion includes an inner surface having a first radius of curvature and an outer surface having a second radius of curvature different from the first radius of curvature, wherein the first radius of curvature is larger than the second radius of curvature.

[0010] According to one embodiment of the present invention, the first radius of curvature is equal to or greater than the second radius of curvature plus R0.5.

[0011] According to one embodiment of the present invention, the first radius of curvature is equal to or greater than R2.5.

[0012] According to one embodiment of the present invention, the second radius of curvature is equal to or less than R2.0.

[0013] According to one embodiment of the present invention, the present invention further includes a cap plate fastened to an opening formed by the first to fourth surfaces, wherein the opening and the cap plate are fastened by welding.

[0014] According to one embodiment of the present invention, the thickness of the first side and the thickness of the second side are the same.

[0015] According to one embodiment of the present invention, the diagonal thickness corresponds to a value obtained by adding the difference between the first radius of curvature and the second radius of curvature to the thickness of the first surface.

[0016] According to one embodiment of the present invention, the first to fourth sides are formed of a material including aluminum.

[0017] According to one embodiment of the present invention for solving the technical problem, a method for manufacturing a can for a secondary battery includes a step of inserting a metal material into a mold, and a step of manufacturing a can by plastically deforming the metal material. The plastically deforming step includes a step of forming a first surface including a long side extending in a first direction, a second surface opposite the first surface and including a long side extending in the first direction, a third surface perpendicular to the first surface and connected to the long side of the first surface and the long side of the second surface, and a fourth surface opposite the third surface and connected to the long side of the first surface and the long side of the second surface, and forming a corner portion formed by the long side of the first surface and the fourth surface connected to the long side of the first surface to have a diagonal thickness thicker than the thicknesses of the first surface and the fourth surface.

[0018] According to one embodiment of the present invention, plastic deformation is caused by extrusion processing.

[0019] According to one embodiment of the present invention, the corner portion includes an inner surface having a first radius of curvature and an outer surface having a second radius of curvature different from the first radius of curvature (R1), wherein the first radius of curvature is larger than the second radius of curvature.

[0020] According to one embodiment of the present invention, the first radius of curvature is equal to or greater than the second radius of curvature plus R0.5.

[0021] According to one embodiment of the present invention, the first radius of curvature is equal to or greater than R2.5.

[0022] According to one embodiment of the present invention, the second radius of curvature is equal to or less than R2.0.

[0023] According to one embodiment of the present invention, the method further comprises the step of fastening a cap plate to an opening formed by the first to fourth surfaces, wherein the opening and the cap plate are fastened by welding.

[0024] According to one embodiment of the present invention, the thickness of the first side and the thickness of the second side are the same.

[0025] According to one embodiment of the present invention, the diagonal thickness corresponds to a value obtained by adding the difference between the first radius of curvature and the second radius of curvature to the thickness of the first surface.

[0026] According to one embodiment of the present invention for solving the above technical problem, a can for a secondary battery includes a first surface including a long side extending in a first direction, a second surface opposite the first surface and including a long side extending in the first direction, a third surface perpendicular to the first surface and connected to the long side of the first surface and the long side of the second surface, a fourth surface opposite the third surface and connected to the long side of the first surface and the long side of the second surface, a fifth surface connected to the short side of each of the first to fourth surfaces, and an opening opposite the fifth surface. A corner portion formed by the short side of the first surface and the fifth surface connected to the short side of the first surface has a diagonal thickness that is thicker than the thicknesses of the first surface and the fifth surface.

[0027] According to one embodiment of the present invention, the corner portion includes an inner side having a third radius of curvature and an outer side having a fourth radius of curvature different from the third radius of curvature, the third radius of curvature is larger than the fourth radius of curvature, the thickness of the first side and the thickness of the fifth side are the same, and the diagonal thickness corresponds to a value obtained by adding the difference between the third radius of curvature and the fourth radius of curvature to the thickness of the first side.

[0028] According to some embodiments of the present invention, by forming the thickness of the corner portion of the can thick, the buckling phenomenon of the can can be prevented.

[0029] According to some embodiments of the present invention, buckling of a long side terminal can be prevented by improving the longitudinal rigidity of the can.

[0030] According to some embodiments of the present invention, it is possible to secure space for welding a cap plate to an opening while increasing the thickness of a corner portion of a can.

[0031] However, the effects that can be obtained through the present invention are not limited to the effects described above, and other technical effects that are not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0032] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0033] FIG. 1 is a perspective view and a cross-sectional view of a can for a secondary battery according to one embodiment of the present invention.

[0034] FIG. 2 is a perspective view and a cross-sectional view of a can for a secondary battery according to another embodiment of the present invention.

[0035] FIG. 3 is a perspective view and a cross-sectional view of a can for a secondary battery according to another embodiment of the present invention.

[0036] FIGS. 4 and 5 are perspective views of a secondary battery assembled using a secondary battery can according to the present disclosure.

[0037] FIG. 6 is a flowchart illustrating a method for manufacturing a secondary battery including a secondary battery can according to the present disclosure of the present invention.

[0038] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms or words used in this specification and claims should not be interpreted as limited to their typical or dictionary meanings, and should be interpreted with meanings and concepts that conform to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of a term to best explain his or her own invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as substitutes for them at the time of filing this application.

[0039] Additionally, when used herein, the terms "comprise", "include" and / or "comprising", "including" specify the presence of stated features, numbers, steps, operations, elements, elements and / or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, elements and / or groups thereof.

[0040] Additionally, to facilitate understanding of the invention, the attached drawings may not be drawn to scale and some components may be exaggerated in size. Furthermore, identical components may be assigned the same reference numbers in different embodiments.

[0041] The statement that two compared objects are "identical" means "substantially identical." Therefore, "substantially identical" may include deviations considered low in the art, such as deviations of less than 5%. Furthermore, uniformity of a parameter over a given region may imply uniformity on average.

[0042] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0043] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0044] Any configuration being placed "on (or under)" or "above (or below)" a component may mean not only that any configuration is placed in contact with the upper surface (or lower surface) of said component, but also that other configurations may intervene between said component and any configuration placed on (or below) said component.

[0045] Additionally, when it is described that a component is "connected," "coupled," or "connected" to another component, it should be understood that the components may be directly connected or connected to each other, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through another component. Furthermore, when it is said that a part is electrically coupled to another part, this includes not only cases where they are directly connected, but also cases where they are connected with another element in between.

[0046] When reference is made throughout the specification to "A and / or B," this means A, B, or A and B, unless otherwise stated. In other words, "and / or" includes all or any combination of the listed items. When reference is made to "C through D," this means C or more and D or less, unless otherwise stated.

[0047] The terminology used herein is for the purpose of describing embodiments of the invention and is not intended to limit the invention.

[0048] FIG. 1 is a perspective view and a cross-sectional view of a can for a secondary battery according to one embodiment of the present invention.

[0049] Referring to FIG. 1, a can (100) for a secondary battery may correspond to a structure for accommodating an electrode assembly. Although not shown, the electrode assembly may include a first electrode plate, a second electrode plate, a separator, etc. The first electrode plate, the second electrode plate, and the separator may each be formed in a thin plate shape or a film shape. The electrode assembly may include a structure in which the first electrode plate, the separator, and the second electrode plate are sequentially laminated and wound, or are repeatedly laminated. When the electrode assembly includes a wound laminate, the winding axis may be a first direction (X-axis). Here, the first direction (X-axis) may correspond to the longitudinal direction of the can (100).

[0050] The can (100) can accommodate an electrode assembly and an electrolyte. The can (100) can include a first side (101), a second side (102), a third side (103), a fourth side (104), a first opening (105), and a second opening (106).

[0051] The first side (101) may include a long side extending in a first direction (X-axis) and a short side extending in a second direction (Y-axis). The first side (101) may have a rectangular shape. The first direction (X-axis) may be the longitudinal direction of the can (100). Here, the first direction (X-axis) may be perpendicular to the second direction (Y-axis).

[0052] The second surface (102) may include a long side extending in the first direction (X-axis) and a short side extending in the second direction (Y-axis). The second surface (102) may have a rectangular shape. The second surface (102) may be opposite the first surface (101). Specifically, the second surface (102) may face the first surface (101) in a third direction (Z-axis). Here, the third direction (Z-axis) may be perpendicular to the first direction (X-axis) and the second direction (Y-axis).

[0053] The length of the long side of the first side (101) and the length of the long side of the second side (102) may be the same. The length of the short side of the first side (101) and the length of the short side of the second side (102) may be the same. The shapes of the first side (101) and the second side (102) may be the same.

[0054] The third side (103) may include a long side extending in the first direction (X-axis) and a short side extending in the third direction (Z-axis). The third side (103) may have a rectangular shape. The third side (103) may be connected to each of the long sides of the first side (101) and the long sides of the second side (102). That is, one of the long sides of the third side (103) may be connected to the long side of the first side (101), and the other of the long sides of the third side (103) may be connected to the long side of the second side (102). The length of the short side of the third side (103) may be greater than the length of the short side of the first side (101).

[0055] The fourth surface (104) may include a long side extending in a first direction (X-axis) and a short side extending in a third direction (Z-axis). The fourth surface (104) may have a rectangular shape. The fourth surface (104) may be opposed to the third surface (103). Specifically, the fourth surface (104) may face the third surface (103) in the second direction (Y-axis). The fourth surface (104) may be connected to each of the long sides of the first surface (101) and the long sides of the second surface (102). That is, one of the long sides of the fourth surface (104) may be connected to the long side of the first surface (101), and the other of the long sides of the fourth surface (104) may be connected to the long side of the second surface (102). The length of the short side of the fourth side (104) may be greater than the length of the short side of the first side (101).

[0056] The first opening (105) may include a long side extending in the third direction (Z-axis) and a short side extending in the second direction (Y-axis). The first opening (105) may have a rectangular shape. The first opening (105) may be defined as a structure formed by the short sides of each of the first to fourth surfaces (101, 102, 103, 104).

[0057] The second opening (106) may be opposed to the first opening (105). Specifically, the second opening (106) may face the first opening (105) in the first direction (X-axis). The second opening (106) may be defined as a structure formed by the short sides of each of the first to fourth surfaces (101, 102, 103, 104). The second opening (106) may be a passage through which an electrode assembly is inserted.

[0058] The first surface (101) and the second surface (102) can cover the surfaces formed in the + Z-axis and - Z-axis directions of the electrode assembly, and the third surface (103) and the fourth surface (104) can cover the surfaces formed in the + Y-axis and - Y-axis directions of the electrode assembly. That is, the first to fourth surfaces (101, 102, 103, 104) surround the electrode assembly in the second direction (Y-axis) and the third direction (Z-axis).

[0059] The material of the can (100) may include a conductive metal such as aluminum, aluminum alloy, stainless steel, and nickel-plated steel.

[0060] According to one embodiment, a corner portion (110) may be formed by a long side of a first surface (101) and a fourth surface (104) that is adjacent to the long side of the first surface (101). A thickness (T1') of the first surface (101) and a thickness (T4') of the fourth surface (104) may be the same. A diagonal thickness (Td') of the corner portion may be the same as a thickness (T1') of the first surface (101) and a thickness (T4') of the fourth surface (104). Each thickness may satisfy the following formula.

[0061]

[0062] Mathematical formula 1

[0063] Diagonal thickness (Td') of the corner (110) = Thickness (T1') of the first surface (101) = Thickness (T4') of the fourth surface (104)

[0064]

[0065] To this end, the corner portion (110) includes an inner surface having a first radius of curvature (R1') and an outer surface having a second radius of curvature (R2') different from the first radius of curvature (R1'). The second radius of curvature (R2') may be larger than the first radius of curvature (R1'). For example, the second radius of curvature (R2') may be equal to a value obtained by adding the thickness (T1') of the first surface or the thickness (T4') of the fourth surface to the first radius of curvature (R1'). That is, each radius of curvature may satisfy the following equation.

[0066]

[0067] Mathematical formula 2

[0068] The second radius of curvature (R2') of the corner portion (110) = the first radius of curvature (R1') of the corner portion (110) + the diagonal thickness (Td') of the corner portion (110) (wherein, the diagonal thickness (Td') of the corner portion (110) = the thickness (T1') of the first surface (101) = the thickness (T4') of the fourth surface (104))

[0069]

[0070] When such a formula is satisfied, a buckling phenomenon of the can (100) may frequently occur. For example, when an uneven load is applied to the can in the Z-axis direction, a phenomenon in which a can formed long in the X-axis direction bends easily occurs. This can be solved by forming the diagonal thickness (Td') of the corner portion (110) thicker than the thickness (T1') of the first surface to the thickness (T4') of the fourth surface.

[0071] FIG. 2 is a perspective view and a cross-sectional view of a can for a secondary battery according to another embodiment of the present invention.

[0072] The can (200) can accommodate an electrode assembly and an electrolyte. The can (200) can include a first side (201), a second side (202), a third side (203), a fourth side (204), a first opening (205), and a second opening (206).

[0073] The can (200) illustrated in FIG. 2 may correspond to a can whose length in the X-axis direction has increased compared to the can (100) illustrated in FIG. 1. For example, the can (200) illustrated in FIG. 2 may have a structure in which the length in the X-axis direction has increased by more than twice compared to the can (100) illustrated in FIG. 1. Since a can (200) having such a structure may more easily undergo a buckling phenomenon, a reinforcing structure is required to prevent this.

[0074] The first side (201) may include a long side extending in a first direction (X-axis) and a short side extending in a second direction (Y-axis). For example, the long side of the first side (201) may have a length that is at least twice as long as the long side of the first side (101) illustrated in FIG. 1. The first side (201) may have a rectangular shape. The first direction (X-axis) may be a longitudinal direction of the can (200). Here, the first direction (X-axis) may be perpendicular to the second direction (Y-axis).

[0075] The second side (202) may include a long side extending in the first direction (X-axis) and a short side extending in the second direction (Y-axis). The second side (202) may have a rectangular shape. The second side (202) may be opposite the first side (201). Specifically, the second side (202) may face the first side (201) in a third direction (Z-axis). Here, the third direction (Z-axis) may be perpendicular to the first direction (X-axis) and the second direction (Y-axis).

[0076] The length of the long side of the first side (201) and the length of the long side of the second side (202) may be the same. The length of the short side of the first side (201) and the length of the short side of the second side (202) may be the same. The shapes of the first side (201) and the second side (202) may be the same.

[0077] The third side (203) may include a long side extending in the first direction (X-axis) and a short side extending in the third direction (Z-axis). The third side (203) may have a rectangular shape. The third side (203) may be connected to each of the long sides of the first side (201) and the long sides of the second side (202). That is, one of the long sides of the third side (203) may be connected to the long side of the first side (201), and the other of the long sides of the third side (203) may be connected to the long side of the second side (202). The length of the short side of the third side (203) may be greater than the length of the short side of the first side (201).

[0078] The fourth side (204) may include a long side extending in a first direction (X-axis) and a short side extending in a third direction (Z-axis). The fourth side (204) may have a rectangular shape. The fourth side (204) may be opposed to the third side (203). Specifically, the fourth side (204) may face the third side (203) in the second direction (Y-axis). The fourth side (204) may be connected to each of the long sides of the first side (201) and the long sides of the second side (202). That is, one of the long sides of the fourth side (204) may be connected to the long side of the first side (201), and the other of the long sides of the fourth side (204) may be connected to the long side of the second side (202). The length of the short side of the fourth side (204) may be greater than the length of the short side of the first side (201).

[0079] The first opening (205) may include a long side extending in the third direction (Z-axis) and a short side extending in the second direction (Y-axis). The first opening (205) may have a rectangular shape. The first opening (205) may be defined as a structure formed by the short sides of each of the first to fourth surfaces (201, 202, 203, 204).

[0080] The second opening (206) may be opposed to the first opening (205). Specifically, the second opening (206) may face the first opening (205) in the first direction (X-axis). The second opening (206) may be defined as a structure formed by the short sides of each of the first to fourth surfaces (201, 202, 203, 204). The second opening (206) may be a passage through which an electrode assembly is inserted.

[0081] According to one embodiment, a corner portion (210) may be formed by a long side of a first surface (201) and a fourth surface (204) connected to the long side of the first surface (201). A diagonal thickness (Td) of the corner portion (210) may be thicker than the thicknesses of the first surface and the fourth surface. To this end, the corner portion (210) includes an inner surface having a first radius of curvature (R1) and an outer surface having a second radius of curvature (R2) different from the first radius of curvature (R1). The first radius of curvature (R1) may be larger than the second radius of curvature (R2). For example, the first radius of curvature (R1) may correspond to a value equal to or greater than the second radius of curvature (R2) plus R0.5. The relationship between the first radius of curvature (R1) and the second radius of curvature (R2) may be expressed as follows.

[0082]

[0083] Mathematical formula 3

[0084] First radius of curvature (R1) > Second radius of curvature (R2)

[0085] Mathematical formula 4

[0086] First radius of curvature (R1) ≥ second radius of curvature (R2) + R0.5

[0087]

[0088] In one embodiment, the first radius of curvature (R1) may be equal to or greater than R2.5. In one embodiment, the second radius of curvature (R2) may be equal to or less than R2.0. With this design, space for welding between the opening of the can and the cap plate is secured, facilitating welding.

[0089] According to one embodiment, the thickness (T1) of the first side (201) and the thickness (T4) of the fourth side (204) are the same, and the diagonal thickness (Td) of the corner portion may be different from the thickness (T1) of the first side (201) and the thickness (T4) of the fourth side (204). That is, each thickness may satisfy the following formula.

[0090]

[0091] Mathematical Formula 5

[0092] Diagonal thickness (Td) of the corner (210) ≠ thickness (T1) of the first surface (201) = thickness (T4) of the fourth surface (204)

[0093]

[0094] More specifically, the diagonal thickness (Td) of the corner portion may be thicker than the thickness (T1) of the first face (201) and the thickness (T4) of the fourth face (204). For example, the diagonal thickness (Td) of the corner portion may correspond to a value obtained by adding the difference between the first radius of curvature (R1) and the second radius of curvature (R2) to the thickness (T1) of the first face (201) when the thickness (T1) of the first face (201) and the thickness (T4) of the fourth face (204) are the same.

[0095]

[0096] Mathematical formula 6

[0097] Diagonal thickness (Td) of the corner portion (210) = thickness (T1) of the first surface (201) + (first radius of curvature (R1) - second radius of curvature (R2)) (At this time, thickness (T1) of the first surface (201) = thickness (T4) of the fourth surface (204))

[0098]

[0099] When designing the corner portion of the can as shown in Fig. 2, compared to Fig. 1, the diagonal thickness of the corner portion can be designed to be thicker than the thickness of the first side and / or the fourth side, thereby more effectively preventing the buckling phenomenon that may occur in the X-axis direction.

[0100] The secondary battery can (200) illustrated in FIG. 2 can be manufactured by extrusion processing. For example, the can (200) may be provided by extrusion into a rectangular cross-section having an internal space. Extrusion is a processing method that allows a rigid material, such as metal, to pass through a die to produce a long product having a cross-section shape identical to the die hole. Since extrusion exerts a high compressive force during processing, the product has a dense structure and excellent mechanical properties. Extrusion methods include cold extrusion and hot extrusion. For example, the can (200) can be manufactured by hot extrusion. Hot extrusion forms an oxide film (insulating film) on the surface of the can (200), thereby preventing an electrical short between the electrode assembly and the can (200). In addition, hot extrusion facilitates the provision of a seamless can (200) (e.g., without a welded area). The thickness of each side, the diagonal thickness of the corners, and the radius of curvature can be adjusted by designing the die.

[0101]

[0102] Fig. 3 is a perspective view and a cross-sectional view of a secondary battery can according to another embodiment of the present invention. Detailed descriptions of components corresponding to those illustrated in Fig. 2 will be omitted, but components different from those illustrated in Fig. 2 will be described.

[0103] The can (300) may include a first side (301), a second side (302), a third side (303), a fourth side (304), a fifth side (305), and an opening (306). Compared to the cans (100, 200) disclosed in FIGS. 1 and 2, the secondary battery can (300) disclosed in FIG. 3 differs in that it has one opening and a fifth side (305) is formed in a direction opposite to the opening.

[0104] The first side (301) may include a long side extending in the first direction (X-axis) and a short side extending in the second direction (Y-axis). The first side (301) may have a rectangular shape.

[0105] The second side (302) may include a long side extending in the first direction (X-axis) and a short side extending in the second direction (Y-axis). The second side (302) may have a rectangular shape. The second side (302) may be opposite to the first side (301).

[0106] The length of the long side of the first side (301) and the length of the long side of the second side (302) may be the same. The length of the short side of the first side (301) and the length of the short side of the second side (302) may be the same. The shapes of the first side (301) and the second side (302) may be the same.

[0107] The third side (303) may include a long side extending in the first direction (X-axis) and a short side extending in the third direction (Z-axis). The third side (303) may have a rectangular shape. The third side (303) may be connected to each of the long side of the first side (301) and the long side of the second side (302).

[0108] The fourth side (304) may include a long side extending in the first direction (X-axis) and a short side extending in the third direction (Z-axis). The fourth side (304) may have a rectangular shape. The fourth side (304) may be opposite the third side (303). The fourth side (304) may be connected to each of the long side of the first side (301) and the long side of the second side (302).

[0109] The fifth surface (305) may include a long side extending in the third direction (Z-axis) and a short side extending in the second direction (Y-axis). The fifth surface (305) may have a rectangular shape. The fifth surface (305) may correspond to a surface formed by connecting to the short sides of each of the first to fourth surfaces (301, 202, 203, 204). Specifically, the long side of the fifth surface (305) may be connected to the short side of the third surface (303) and the short side of the fourth surface (304), respectively. The short side of the fifth surface (305) may be connected to the short side of the first surface (301) and the short side of the second surface (302), respectively.

[0110] The opening (306) may be opposed to the fifth surface (305). Specifically, the opening (306) may face the fifth surface (305) in the first direction (X-axis). The opening (306) may be defined as a structure formed by a short side of each of the first to fourth surfaces (301, 302, 303, 304). The opening (306) may be a passage through which an electrode assembly is inserted.

[0111] According to one embodiment, a corner portion (310) may be formed by a short side of a first surface (301) and a fifth surface (305) connected to the short side of the first surface (301). A diagonal thickness (Td) of the corner portion (310) may be thicker than the thicknesses of the first surface and the fifth surface. To this end, the corner portion (310) includes an inner surface having a third radius of curvature (R3) and an outer surface having a fourth radius of curvature (R4) different from the third radius of curvature (R3). The third radius of curvature (R3) may be larger than the fourth radius of curvature (R4). For example, the third radius of curvature (R3) may correspond to a value equal to or greater than the fourth radius of curvature (R4) plus R0.5. The relationship between the third radius of curvature (R3) and the fourth radius of curvature (R4) may be expressed as follows.

[0112]

[0113] Mathematical formula 7

[0114] Third radius of curvature (R3) > Fourth radius of curvature (R4)

[0115] Mathematical formula 8

[0116] Third radius of curvature (R3) ≥ fourth radius of curvature (R4) + R0.5

[0117]

[0118] According to one embodiment, the thickness (T1) of the first side (301) and the thickness (T5) of the fifth side (305) are the same, and the diagonal thickness (Td) of the corner portion may be different from the thickness (T1) of the first side (301) and the thickness (T5) of the fifth side (305). That is, each thickness may satisfy the following formula.

[0119]

[0120] Mathematical formula 9

[0121] Diagonal thickness (Td) of the corner (310) ≠ thickness (T1) of the first surface (301) = thickness (T5) of the fifth surface (304)

[0122]

[0123] More specifically, the diagonal thickness (Td) of the corner portion may be thicker than the thickness (T1) of the first face (301) and the thickness (T5) of the fifth face (304). For example, the diagonal thickness (Td) of the corner portion may correspond to a value obtained by adding the difference between the third radius of curvature (R3) and the fourth radius of curvature (R4) to the thickness (T1) of the first face (301) when the thickness (T1) of the first face (301) and the thickness (T5) of the fifth face (305) are the same.

[0124]

[0125] Mathematical formula 10

[0126] Diagonal thickness (Td) of the corner (310) = thickness (T1) of the first surface (301) + (third radius of curvature (R3) - fourth radius of curvature (R4)) (At this time, thickness (T1) of the first surface (301) = thickness (T5) of the fifth surface (304))

[0127]

[0128] When designing the corner portion of the can as shown in Fig. 3, compared to Fig. 1, the diagonal thickness of the corner portion can be designed to be thicker than the thickness of the first side and / or the fifth side, thereby more effectively preventing a buckling phenomenon that may occur in a direction other than the X-axis.

[0129] The first to fifth sides (301, 302, 303, 304, 305) of the secondary battery can (300) illustrated in FIG. 3 can be formed integrally. The first to fifth sides (301, 102, 303, 304, 305) of the can (300) can be formed integrally, for example, by a deep drawing process. The deep drawing process is a process in which, in press processing of a plate material, a punch and a die are used to press the outer periphery of the plate inward, thereby producing a container having a bottom and a seamless joint. In the deep drawing process, the thickness of each side, the diagonal thickness of the corners, and the radius of curvature can be adjusted through the design of the punch and the die.

[0130] FIGS. 4 and 5 are perspective views of a secondary battery assembled using a secondary battery can according to the present disclosure.

[0131] The secondary battery may include a can (400), an electrode assembly (410), a vent member (460), a first terminal plate (431), a first insulating member (not shown), and a cap assembly (430).

[0132] The electrode assembly (410) may be accommodated inside the can (100). Although not shown, the electrode assembly (410) may include a first electrode plate, a second electrode plate, a separator, etc. The first electrode plate, the second electrode plate, and the separator may each be formed in a thin plate shape or a film shape. The electrode assembly (410) may include a structure in which the first electrode plate, the separator, and the second electrode plate are sequentially laminated and wound, or are repeatedly laminated. When the electrode assembly (410) includes a wound laminate, the winding axis may be a first direction (X-axis). Here, the first direction (X-axis) may be a longitudinal direction of the can (400).

[0133] The first electrode plate can function as a cathode. The first electrode plate can include a cathode coated portion in which a cathode active material is coated on a conductive metal thin plate made of copper, a copper alloy, nickel, or a nickel alloy, and a cathode uncoated portion in which the cathode active material is not coated. The cathode active material can include, for example, a carbon-based material, silicon, or the like. However, the cathode active material according to the present disclosure is not limited thereto.

[0134] The second electrode plate can function as an anode. The second electrode plate can include a cathode-coated portion, in which a cathode active material is coated on a conductive metal thin plate, such as aluminum, and a cathode-free portion, in which the cathode active material is not coated. The cathode active material can include, for example, lithium cobalt oxide. However, the composition of the cathode active material according to the present disclosure is not limited thereto.

[0135] A separator may be interposed between the first electrode plate and the second electrode plate. The separator may prevent an electrical short between the first electrode plate and the second electrode plate. The separator may include, for example, polyethylene, polypropylene, a porous hollow polymer of polyethylene and polypropylene, etc. However, the composition of the separator according to the present disclosure is not limited thereto.

[0136] The sub-plate assembly (420) may be disposed on one side of the electrode assembly (410). The sub-plate assembly (420) may be electrically connected to the first electrode plate (e.g., the negative electrode plate) and the second electrode plate (e.g., the positive electrode plate) of the electrode assembly (410), respectively. The sub-plate assembly (420) may be electrically connected to a terminal plate (431) to be described later. The electrode assembly (410) may be electrically connected to the terminal plate (431) through the sub-plate assembly (420). The sub-plate assembly (420) may also be disposed on the other side of the electrode assembly (410). Specifically, the sub-plate assembly (420) may be disposed on both sides of the electrode assembly (410).

[0137] The electrode assembly (410) may be provided with the sub-plate assembly (420) coupled to one end of the electrode assembly (410) and then coupled to the other end. The electrode assembly (410) may be inserted in the first direction (X-axis) through the second opening (406) of the can (400).

[0138] In one embodiment, the subplate assembly (420) may include a subplate and a current collecting structure. The subplate may be connected to a tab formed on the negative electrode non-conductive portion. The current collecting structure may be disposed on the subplate. The current collecting structure may include a protrusion (421). The protrusion (421) of the current collecting structure may contact the terminal plate (431).

[0139] The cap assembly (430) may include a cap plate (433), an insulating member (432), and a terminal plate (431).

[0140] The cap plate (433) can be welded to the opening (405, 406) of the can (400). The cap plate (433) can seal one or both ends of the can (400).

[0141] The cap plate (433) can be welded and joined to the openings (405, 406) of the can (400). Specifically, the cap plate (433) of the cap assembly (430) is placed on the openings (405, 406) of the can (400) and can be welded to the short sides of each of the first to fourth sides (401, 402, 403, 404). The cap plate (433) is welded to the can (100), so that the can (100) can be sealed.

[0142] The cap plate (433) may have a rectangular plate shape. A hole may be formed in the cap plate (433). An insulating member (432) may be coupled onto the hole. A terminal plate (431) may be coupled onto the insulating member (432). The insulating member (432) may seal between the cap plate (433) and the terminal plate (431). At least a portion of the cap plate (433) and the terminal plate (431) may be insulated by the insulating member (432).

[0143] The terminal plate (431) can be in contact with the sub-plate assembly (420). The terminal plate (431) can be electrically connected to the electrode assembly (410) through the sub-plate assembly (420).

[0144] The terminal plate (431) can be welded and joined to the sub-plate assembly (420). As a result, the cap assembly (430) can be joined to the sub-plate assembly (420). The sub-plate assembly (420) and the terminal plate (431) can be welded after the cap assembly (430) is joined.

[0145] The cap assembly (430) can be coupled to the first opening (405) and the second opening (406) of the can (400). The cap assembly (430) can be positioned in the openings (405, 406) and welded along the openings (405, 406) to seal the can (400). In FIG. 4, the cap assembly (430) is shown as being positioned spaced apart from the electrode assembly (410), but this is for illustrating the structure of the cap assembly (430), and the present disclosure is not limited thereto.

[0146] The vent member (460) may be disposed on the first surface (401) of the can (400). Specifically, a vent hole may be formed on the first surface (401) of the can (400), and the vent member (460) may be coupled to the vent hole. The vent hole may have a shape corresponding to the vent member (460). Additionally, the vent hole may be formed on the second surface (402) of the can (400). Alternatively, the vent hole may not be formed on the first surface (401) of the can (400), but may be formed only on the second surface (402) of the can (400). The vent member (460) may be configured to open when the internal pressure of the secondary battery exceeds a predetermined threshold pressure. The vent member (460) can prevent explosion of the secondary battery or prevent a chain heating reaction of another secondary battery placed in close proximity to one secondary battery.

[0147] In some embodiments, the vent member (460) may include a notch. The notch may be removed from the first surface (401) by a predetermined thickness or may be at least one flaw. The notch may be ruptured when the internal pressure of the can (400) exceeds a critical pressure.

[0148] A can having openings (405, 406) on both sides can be manufactured and formed by welding a cap plate to each opening. In FIG. 4, the first opening (405) is shown as having already been welded by the cap plate, and the second opening (406) is shown as having not yet been welded by the cap plate. However, the present disclosure is not limited to this welding order. After the electrode assembly (410) is inserted into the can (400), one of the first opening (405) and the second opening (406) can be sealed by the cap plate, and then the other can be sealed by the cap plate.

[0149] FIG. 6 is a flowchart illustrating a method for manufacturing a secondary battery including a can for a secondary battery according to the present disclosure.

[0150] A method for manufacturing a secondary battery according to one embodiment of the present invention may begin with a step of inserting a metal material into a mold (S610). The metal material may include a conductive metal such as aluminum, an aluminum alloy, stainless steel, and nickel-plated steel.

[0151] Next, a can is manufactured by plastically deforming the metal material (S620). By applying pressure to the metal material using a mold, the metal material can be plastically deformed into a specific shape. For example, plastic deformation can be achieved through extrusion. Through extrusion, the can can be extruded into a rectangular cross-section with an internal space.

[0152] In the plastic deformation step, a first surface including a long side extending in a first direction, a second surface opposite the first surface and including a long side extending in the first direction, a third surface perpendicular to the first surface and connected to the long side of the first surface and the long side of the second surface, and a fourth surface opposite the third surface and connected to the long side of the first surface and the long side of the second surface can be formed. In addition, in the plastic deformation step, a corner portion formed by the long side of the first surface and the fourth surface connected to the long side of the first surface can be formed to have a diagonal thickness that is thicker than the thicknesses of the first surface and the fourth surface.

[0153] At this time, the corner portion includes an inner surface having a first radius of curvature (R1) and an outer surface having a second radius of curvature (R2) different from the first radius of curvature (R1), and the first radius of curvature is larger than the second radius of curvature.

[0154] In one embodiment, the first radius of curvature is equal to or greater than the second radius of curvature plus R0.5.

[0155] In one embodiment, the first radius of curvature is equal to or greater than R2.5, and the second radius of curvature is equal to or less than R2.0. By designing the radius of curvature in this manner, space for welding between the opening of the can and the cap plate is secured, thereby facilitating welding.

[0156] In one embodiment, the thickness of the first side and the thickness of the second side are the same.

[0157] According to one embodiment, the diagonal thickness of the corner portion corresponds to a value obtained by adding the difference between the first radius of curvature and the second radius of curvature to the thickness of the first surface.

[0158] Subsequently, the electrode assembly is inserted into the can (S630). The subplate assembly is connected to both ends of the electrode assembly and can be inserted in the first direction (X-axis), for example, through an opening in the can.

[0159] Next, the cap assembly is welded to the can (S640). The cap plate of the cap assembly can be welded to the opening of the can. The cap plate can seal one or both ends of the can. The cap plate of the cap assembly is positioned over the opening of the can and can be welded to the short sides of each of the first to fourth sides.

[0160] A can can be formed by manufacturing a can having openings at both ends and welding a cap plate to each of the openings. After the electrode assembly is inserted into the can, one of the first opening and the second opening can be sealed by the cap plate, and then the other can be sealed by the cap plate.

[0161] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

Claims

1. A first surface including a long side extending in a first direction; A second side including a longitudinal side extending in the first direction and facing the first side; A third surface perpendicular to the first surface and connected to the long side of the first surface and the long side of the second surface; A fourth surface facing the third surface and connected to the long side of the first surface and the long side of the second surface Including, A can for a secondary battery, wherein a corner portion formed by a long side of the first surface and a fourth surface connected to the long side of the first surface has a diagonal thickness that is thicker than the thicknesses of the first surface and the fourth surface.

2. In paragraph 1, The above corner portion includes an inner surface having a first radius of curvature and an outer surface having a second radius of curvature different from the first radius of curvature, A can for a secondary battery, wherein the first radius of curvature is larger than the second radius of curvature.

3. In paragraph 2, A can for a secondary battery, wherein the first radius of curvature is equal to or greater than the second radius of curvature plus R0.

5.

4. In paragraph 3, A can for secondary batteries with a first radius of curvature of R2.5 or greater.

5. In paragraph 4, A can for secondary batteries with a second radius of curvature of R2.0 or less.

6. In paragraph 5, A cap plate fastened to an opening formed by the first to fourth surfaces Including more, A can for a secondary battery, wherein the above opening and the cap plate are connected by welding.

7. In paragraph 2, A can for a secondary battery, wherein the thickness of the first side and the thickness of the second side are the same.

8. In paragraph 7, A can for a secondary battery, wherein the above diagonal thickness corresponds to a value obtained by adding the difference between the first radius of curvature and the second radius of curvature to the thickness of the first surface.

9. In paragraph 8, A can for a secondary battery, wherein the first to fourth sides are formed of a material containing aluminum.

10. A method for manufacturing a can for a secondary battery, A step of inserting a metal material into a mold; and A step for manufacturing a can by plastically deforming the above metal material. Including, The above plastic deformation step is, A first surface including a longitudinal side extending in a first direction; A second side including a longitudinal side extending in the first direction and facing the first side; A third surface perpendicular to the first surface and connected to the long side of the first surface and the long side of the second surface; A fourth surface facing the third surface and connected to the long side of the first surface and the long side of the second surface , and form A method for manufacturing a can for a secondary battery, comprising a step of forming a corner portion formed by a long side of the first surface and a fourth surface connected to the long side of the first surface to have a diagonal thickness thicker than the thicknesses of the first surface and the fourth surface.

11. In paragraph 10, A method for manufacturing a can for a secondary battery, wherein the above plastic deformation is performed by extrusion processing.

12. In paragraph 11, The above corner portion includes an inner surface having a first radius of curvature and an outer surface having a second radius of curvature different from the first radius of curvature, A method for manufacturing a can for a secondary battery, wherein the first radius of curvature is larger than the second radius of curvature.

13. In paragraph 12, A method for manufacturing a can for a secondary battery, wherein the first radius of curvature is equal to or greater than the second radius of curvature plus R0.

5.

14. In paragraph 13, A method for manufacturing a can for a secondary battery, wherein the first radius of curvature is R2.5 or greater.

15. In paragraph 14, A method for manufacturing a can for a secondary battery, wherein the second radius of curvature is R2.0 or less.

16. In paragraph 14, A step of attaching a cap plate to the opening formed by the first to fourth surfaces. Including more, A method for manufacturing a can for a secondary battery, wherein the above opening and the cap plate are connected by welding.

17. In paragraph 12, A method for manufacturing a can for a secondary battery, wherein the thickness of the first side and the thickness of the second side are the same.

18. In paragraph 17, A method for manufacturing a can for a secondary battery, wherein the above diagonal thickness corresponds to a value obtained by adding the difference between the first radius of curvature and the second radius of curvature to the thickness of the first side.

19. A first surface including a longitudinal side extending in a first direction; A second side including a longitudinal side extending in the first direction and facing the first side; A third surface perpendicular to the first surface and connected to the long side of the first surface and the long side of the second surface; A fourth surface opposite to the third surface and connected to the long side of the first surface and the long side of the second surface; A fifth surface connected to each of the short sides of the first to fourth surfaces; and An opening opposite to the fifth side above Including, A can for a secondary battery, wherein a corner portion formed by a short side of the first surface and a fifth surface connected to the short side of the first surface has a diagonal thickness that is thicker than the thicknesses of the first surface and the fifth surface.

20. In paragraph 19, The above corner portion includes an inner surface having a third radius of curvature and an outer surface having a fourth radius of curvature different from the third radius of curvature, The above third radius of curvature is larger than the above fourth radius of curvature, The thickness of the first side and the thickness of the fifth side are the same, A can for a secondary battery, wherein the above diagonal thickness corresponds to a value obtained by adding the difference between the third radius of curvature and the fourth radius of curvature to the thickness of the first surface.

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