Secondary battery

Abstract

A secondary battery includes: an electrode assembly; a can configured to accommodate the electrode assembly, the can including an open upper portion, a side portion, and a crimp portion and a crimp portion on the side portion of the can; a cover plate located between the rolled portion and the crimped portion of the can, the cover plate configured to close the open upper portion of the can; a first gasket located between the can and an edge portion of the cover plate, the first gasket including an upper end located at the same height as or lower than an upper surface of the edge portion of the cover plate; and a terminal electrically connected to the electrode assembly.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to a secondary battery. Background Art

[0002] Lithium ion secondary batteries are used as power sources for hybrid vehicles, electric vehicles, and portable electronic devices due to their relatively high operating voltage and relatively high energy density per unit weight.

[0003] Such secondary batteries can be classified into cylindrical, prismatic, or pouch-shaped secondary batteries according to their shapes. A cylindrical secondary battery is generally assembled by inserting an electrode assembly together with an electrolyte into a can formed in a cylindrical shape. Then, a crimping portion is formed in the can such that the upper portion of the side portion of the can is recessed inward. Then, a cover plate and a gasket are positioned on the crimping portion. Then, the upper portion of the can is closed by forming a crimping portion that is bent inward together with the gasket so that the upper end of the side portion of the can covers the edge portion of the cover plate. However, in the process of forming the crimping portion, the gasket may be radially bent or otherwise deformed inward, which generates undesirable wrinkles in the gasket.

[0004] The information disclosed in this background art section is for enhancing the understanding of the background art of the present disclosure, and thus, it may include information that does not constitute related art. Summary of the Invention

[0005] Embodiments of the present disclosure provide a secondary battery capable of improving the quality of a gasket when forming a crimping portion.

[0006] A secondary battery according to an embodiment of the present disclosure includes: an electrode assembly; a can accommodating the electrode assembly and including an open upper portion, a side portion, and a crimping portion and a crimping portion on the side portion of the can; a cover plate positioned between the crimping portion and the crimping portion of the can and configured to close the upper portion of the can; a first gasket positioned between the can and the edge portion of the cover plate and having an upper end at a height equal to or lower than the upper surface of the edge portion of the cover plate; and a terminal electrically connected to the electrode assembly.

[0007] In addition, the upper end of the side portion of the can may be in direct contact with the upper surface of the edge portion of the cover plate.

[0008] In addition, the upper end of the side portion of the can may be welded to the upper surface of the edge portion of the cover plate.

[0009] In addition, a second gasket may be positioned between the upper end of the side portion of the can and the upper surface of the edge portion of the cover plate.

[0010] In addition, the second gasket may be formed in an annular shape having a width in a direction parallel to the upper surface of the edge portion of the cover plate.

[0011] In addition, the second gasket may extend radially inward further than the upper end of the side portion of the can.

[0012] In addition, the first gasket and the second gasket may be separately formed.

[0013] In addition, the first gasket may include: a side section located between the area between the crimping portion and the caulking portion of the can and the outer surface of the edge portion of the cover plate, including the upper end of the first gasket; and a lower section located between the crimping portion of the can and the lower surface of the edge portion of the cover plate.

[0014] In addition, the upper end of the side section may be located at the same height as the upper surface of the edge portion of the cover plate or lower than the upper surface of the edge portion of the cover plate.

[0015] In addition, the side section and the lower section may be integrally formed.

[0016] In addition, the ratio of the height of the side section to the distance between the crimping portion and the caulking portion of the can may be in the range of approximately 30% to approximately 60%.

[0017] In addition, the ratio of the total height of the first gasket to the distance between the crimping portion and the caulking portion of the can may be in the range of approximately 65% to approximately 90%.

[0018] In addition, the ratio of the height of the side section to the total height of the first gasket may be in the range of approximately 35% to approximately 70%.

[0019] In addition, the cover plate may include a step such that the upper surface of the edge portion of the cover plate is lower than the upper surface of the central portion of the cover plate.

[0020] In addition, the step may include a portion connecting the edge portion of the cover plate to the central portion of the cover plate, and the portion is inclined.

[0021] In addition, a part of the upper surface of the edge portion of the cover plate may be cut to form the step.

[0022] In addition, the terminal may be mounted in the cover plate, and the secondary battery may include an insulating member located between the cover plate and the terminal.

[0023] In addition, the lower portion of the can may include a notch configured to serve as a safety vent.

[0024] In addition, the terminal may be mounted in the lower portion of the can, and the secondary battery may further include an insulating member located between the can and the terminal.

[0025] In addition, the cover plate may include a notch configured to serve as a safety vent. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a cross-sectional view of a secondary battery according to a first embodiment of the present disclosure.

[0027] Figure 2 is Figure 1 an enlarged view of part II of

[0028] Figure 3 is a cross-sectional view of a secondary battery according to a second embodiment of the present disclosure.

[0029] Figure 4 is Figure 3 an enlarged view of part IV of

[0030] Figure 5 is a cross-sectional view of a secondary battery according to a third embodiment of the present disclosure.

[0031] Figure 6 is Figure 5 an enlarged view of part VI of

[0032] Figure 7 is a cross-sectional view of a secondary battery according to a fourth embodiment of the present disclosure.

[0033] Figure 8 is Figure 7 an enlarged view of part VIII of DETAILED DESCRIPTION

[0034] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the drawings.

[0035] Embodiments of the present disclosure are provided to more fully describe the present disclosure to those skilled in the art, and the following embodiments may be modified in many different forms, and the scope of the present disclosure is not limited to the following embodiments. On the contrary, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the spirit of the present disclosure to those skilled in the art.

[0036] In addition, in the following drawings, for the convenience and clarity of illustration, the thickness or size of each layer is enlarged, and the same reference numerals refer to the same elements in the drawings. As used in this specification, the term "and / or" may include any and all combinations of one or more of the associated listed items. Additionally, in this specification, it should be understood that when component A is referred to as being "connected to" component B, component A may be directly connected to component B, or component C may be interposed between component A and component B such that component A is indirectly connected to component B.

[0037] The terms used herein are for the purpose of describing particular embodiments and are not intended to limit the disclosure. As used in this specification, the singular forms may include the plural forms unless specifically indicated otherwise by the context. Additionally, the terms "comprises" and / or "comprising," when used in this specification, specifically specify the presence of the stated features, quantities, steps, operations, components, elements, and / or groups thereof, but do not preclude the presence or addition of one or more other features, quantities, steps, operations, components, elements, and / or groups thereof.

[0038] In this specification, although terms such as "first," "second," etc. may be used to describe various components, parts, regions, layers, and / or portions, these components, parts, regions, layers, and / or portions are not limited by these terms. These terms are used to distinguish one component, part, region, layer, or portion from another component, part, region, layer, or portion. Thus, without departing from the teachings of the disclosure, the first component, part, region, layer, or portion described below may also be the second component, part, region, layer, or portion.

[0039] Spatial relative terms such as "beneath," "below," "lower," "above," and "upper" may be used herein to facilitate an understanding of one element or feature illustrated in the drawings in relation to another element or feature. These spatial relative terms are intended to facilitate an understanding of the disclosure in accordance with various process states or usage states of the disclosure and are not intended to limit the disclosure. For example, when an element or feature in the drawings is flipped, an element or feature described as "beneath" or "lower" may be described as "above" or "upper." Thus, the term "beneath" may encompass the terms "above" or "below."

[0040] Figure 1 is a cross-sectional view of a secondary battery 100 according to a first embodiment of the present disclosure, and Figure 2 is Figure 1 an enlarged view of part II of

[0041] Refer to Figure 1 and Figure 2, a secondary battery 100 according to a first embodiment of the present disclosure includes an electrode assembly 110, a can 120, a cover plate 130, a first gasket 140, terminals 150, an insulating member 160, a first electrode lead 170, and a second electrode lead 180.

[0042] The electrode assembly 110 includes a first electrode plate 111, a second electrode plate 112, and a separator 113.

[0043] The first electrode plate 111 may be a negative electrode plate or a positive electrode plate. In an embodiment where the first electrode plate 111 is a negative electrode plate, the first electrode plate 111 includes a base material (negative electrode base material) having a coated portion (negative electrode coated portion) coated with an active material (negative electrode active material) and an uncoated portion (negative electrode uncoated portion) not coated with the active material (negative electrode active material). The base material may be made of a conductive metal thin plate (e.g., copper foil, nickel foil, or mesh). The negative electrode active material may include, for example, carbon-based materials, Si, Sn, tin oxide, tin alloy composites, transition metal oxides, lithium nitrite, or metal oxides.

[0044] The second electrode plate 112 may be the other of the negative electrode plate and the positive electrode plate. In an embodiment where the second electrode plate 112 is a positive electrode plate, the second electrode plate 112 includes a base material (positive electrode base material) having a coated portion (positive electrode coated portion) coated with a positive electrode active material and an uncoated portion (positive electrode uncoated portion) not coated with the active material (positive electrode active material). The base material (positive electrode base material) may be made of a conductive metal thin plate, such as aluminum foil or mesh. The positive electrode active material may include chalcogen compounds, such as composite metal oxides, such as LiCoO2, LiMn2O4, LiNiO2, LiNiMnO2, etc.

[0045] The separator 113 is located between the first electrode plate 111 and the second electrode plate 112 and is configured to prevent a short circuit between the first electrode plate 110 and the second electrode plate 112. The separator 113 may be made of, for example, polyethylene, polypropylene, a porous copolymer of polyethylene and polypropylene, etc.

[0046] The electrode assembly 110 may be formed by sequentially stacking the first electrode plate 111, the separator 113, the second electrode plate 112, and the separator 113 and winding the first electrode plate 111, the separator 113, the second electrode plate 112, and the separator 113 into a so-called pole core shape.

[0047] The can 120 may be formed in a cylindrical shape. In one or more embodiments, the can 120 may include a lower portion 121 formed in a disk shape and a side portion 122 extending upward from the circumference of the lower portion 121. The upper portion of the can 120 is open, so that the electrode assembly 110 may be inserted into the can 120 together with the electrolyte through the upper portion of the can 120. The upper portion of the can 120 may be closed using a cover plate 130.

[0048] In the can 120, the lower portion 121 may be integrally formed with the side portion 122.

[0049] The can 120 may include a notch 121a configured to serve as a safety vent in the lower portion 121. Thus, when gas is generated due to abnormal operation of the secondary battery 100 and the internal pressure of the secondary battery 100 rises above a certain pressure, the pressure may cause a cut along the notch 121a to allow the notch 121a to open and discharge the gas, thereby preventing an explosion.

[0050] In addition, the can 120 may include a caulking portion 122a and a crimping portion 122b on the side portion 122. The caulking portion 122a is configured to fix the electrode assembly 110 in place and accommodate the cover plate 130. The caulking portion 122a is formed by recessing the upper portion of the side portion 122 of the can 120 inward. The crimping portion 122b is configured to fix the cover plate 130 and is formed by bending the upper end of the side portion 122 of the can 120 inward to cover the edge portion 131 of the cover plate 130.

[0051] The can 120 may be made of, for example, steel, steel alloy, aluminum, aluminum alloy, etc.

[0052] The cover plate 130 is coupled to the upper portion of the can 120 and is located between the caulking portion 122a and the crimping portion 122b of the can 120.

[0053] In one or more embodiments, during the assembly process of accommodating the electrode assembly 110 in the can 120, the caulking portion 122a may be formed such that the upper portion of the side portion 122 of the can 120 is recessed inward, and then the cover plate 130 may be placed on the caulking portion 122a together with the first gasket 140. Then, the crimping portion 122b may be formed such that the upper end of the side portion 122 of the can 120 is bent inward to cover the edge portion 131 of the cover plate 130, thereby installing the cover plate 130.

[0054] In addition, the upper end of the side portion 122 of the can 120 may be welded in direct contact with the edge portion 131 of the cover plate 130. In one or more embodiments, the welding may be performed by irradiating the upper end of the side portion 122 of the can 120 with a laser from above, and the welding may be performed continuously along the edge portion 131 of the cover plate 130, that is, in a circular manner. Accordingly, the gap between the upper end of the side portion 122 of the can 120 and the edge portion 131 of the cover plate 130 may be minimized or at least reduced, so that the can 120 and the cover plate 130 are tightly joined together.

[0055] In addition, the cover plate 130 may include a step such that the upper surface of the edge portion 131 of the cover plate 130 is lower than the upper surface of the central portion 132 of the cover plate 130. In one or more embodiments, the portion connecting the edge portion 131 of the cover plate 130 to the central portion 132 may be bent to be inclined (i.e., oblique) such that the edge portion 131 may be completely located below the central portion 132, or the upper surface of the edge portion 131 of the cover plate 130 may be partially cut such that the upper surface of the edge portion 131 may be lower than the upper surface of the central portion 132. The former case is illustrated in the drawings. The height of the step may correspond to (or substantially correspond to) the thickness of the can 120. Therefore, when the upper end of the side portion 122 of the can 120 is bent inward to cover the edge portion 131 of the cover plate 130, it is possible to prevent the upper end of the side portion 122 of the can 120 from protruding upward relative to the cover plate 130.

[0056] The cover plate 130 includes a terminal hole 132a for mounting the terminal 150. The terminal hole 132a may be formed through the center (or substantially the center) of the central portion 132 of the cover plate 130.

[0057] The first gasket 140 is located between the can 120 and the edge portion 131 of the cover plate 130 and is configured to prevent electrolyte from leaking to the outside and to prevent foreign substances such as moisture or dust from flowing into the interior of the can 120.

[0058] In one or more embodiments, the first gasket 140 includes a side section 141 between the outer surface of the edge portion 131 of the cover plate 130 and the area between the crimping portion 122a and the crimping portion 122b of the can 120, and a lower section 142 between the crimping portion 122a of the can 120 and the lower surface of the edge portion 131 of the cover plate 130.

[0059] The side section 141 surrounds the outer surface of the edge portion 131 of the cover plate 130. In one or more embodiments, the side section 141 may not protrude higher than the upper surface of the edge portion 131 of the cover plate 130. In one or more embodiments, the upper end of the side section 141 may be located at a height substantially the same as or slightly lower than the upper surface of the edge portion 131 of the cover plate 130. In the drawings, the upper end of the side section 141 is illustrated as being located at the same height as the upper surface of the edge portion 131 of the cover plate 130. Thus, when forming the crimp portion 122b, the upper end of the side portion 122 of the can 120 can be in full close contact with the edge portion 131 of the cover plate 130 so as not to interfere with the side section 141.

[0060] To ensure the sealing strength of the cover plate 130, the ratio T2 / T1 of the height T2 of the side section 141 to the distance T1 between the curled portion 122a and the crimp portion 122b of the can 120 may be in the range of approximately 30% to approximately 60%. In one or more embodiments, the distance T1 between the curled portion 122a and the crimp portion 122b of the can 120 may be about (approx.) 2.25 mm, and the height T2 of the side section 141 may be about (approx.) 1.00 mm, such that the ratio T2 / T1 is about (approx.) 44.4%.

[0061] The lower section 142 contacts the lower surface of the edge portion 131 of the cover plate 130. The thickness of the lower section 142 may be slightly compressed relative to its initial thickness during the process of forming the crimp portion 122b.

[0062] To ensure the sealing strength of the cover plate 130 while avoiding interference with other components (such as the electrode assembly 110 and / or the second electrode lead 180), the ratio T3 / T1 of the total height T3 of the first gasket 140 to the distance T1 between the curled portion 122a and the crimp portion 122b of the can 120 may be in the range of approximately 65% to approximately 95%. In one or more embodiments, the distance T1 between the curled portion 122a and the crimp portion 122b of the can 120 may be about (approx.) 2.25 mm, and the total height T3 of the first gasket 140 may be about (approx.) 1.90 mm, such that the ratio of T3 / T1 is about (approx.) 84.4%. Additionally, the ratio T2 / T3 of the height T2 of the side section 141 to the total height T3 of the first gasket 140 may be in the range of approximately 35% to approximately 70%. In one or more embodiments, the total height T3 of the first gasket 140 may be about (approx.) 1.90 mm, and the height T2 of the side section 141 may be about (approx.) 1.00 mm, such that the ratio T2 / T3 is about (approx.) 52.6%.

[0063] In the first gasket 140, the side section 141 may be integrally formed with the lower section 142.

[0064] In addition, the first gasket 140 can be made of, for example, polypropylene (PP), polyethylene (PE), ethylene propylene diene monomer (EPDM), nitrile butadiene rubber (NBR), etc.

[0065] The terminal 150 is installed in the terminal hole 132a of the cover plate 130.

[0066] The terminal 150 can be installed, for example, by riveting. In one or more embodiments, after the terminal 150 is inserted into the terminal hole 132a from above the cover plate 130, the downward insertion portion (i.e., the lower side portion) of the terminal 150 can be deformed to have a diameter larger than the diameter of the terminal hole 132a, such that the terminal 150 is supported on the lower surface of the central portion 132 of the cover plate 130 and fixed to the lower surface of the central portion 132 of the cover plate 130. In one or more embodiments, the upper side portion of the terminal 150 located above the cover plate 130 can be formed to have a diameter larger than the diameter of the terminal hole 132a, and the upper side portion of the terminal 150 can be supported on the upper surface of the central portion 132 of the cover plate 130. After the terminal 150 is inserted into the terminal hole 132a from below the cover plate 130, the upwardly protruding upper side portion of the terminal 150 can be deformed to have a diameter larger than the diameter of the terminal hole 132a, such that the upper side portion of the terminal 150 is supported on the upper surface of the central portion 132 of the cover plate 130 and fixed to the upper surface of the central portion 132 of the cover plate 130. The lower side portion of the terminal 150 located below the cover plate 130 can have a diameter larger than the diameter of the terminal hole 132a, and the lower side portion of the terminal 150 can be supported on the lower surface of the central portion 132 of the cover plate 130.

[0067] The insulating member 160 is located between the cover plate 130 and the terminal 150, and is configured to electrically insulate the cover plate 130 and the terminal 150 from each other, and prevent the electrolyte from leaking to the outside and prevent foreign substances such as moisture or dust from flowing into the interior of the can 120.

[0068] In one or more embodiments, the insulating member 160 can include a portion between the upper surface of the central portion 132 of the cover plate 130 and the upper side portion of the terminal 150, a portion between the inner peripheral surface of the terminal hole 132a of the cover plate 130 and the portion connecting the upper side portion and the lower side portion of the terminal 150, and a portion between the lower surface of the central portion 132 of the cover plate 130 and the lower side portion of the terminal 150. In order to further prevent other components (such as the electrode assembly 110 and / or the second electrode lead 180) from inadvertently contacting the cover plate 130, the entire portion of the insulating member 160 between the lower surface of the central portion 132 of the cover plate 130 and the lower side portion of the terminal 150 can be widely formed over the lower surface of the central portion 132 of the cover plate 130.

[0069] The first electrode lead 170 is configured to electrically connect the first electrode plate 111 of the electrode assembly 110 to the can 120. In one or more embodiments, the first electrode lead 170 may have one end welded to the uncoated portion of the first electrode plate 111 and the other end welded to the lower portion 121 of the can 120.

[0070] Accordingly, when the first electrode plate 111 is the negative electrode plate as described above, the can 120 serves as the negative electrode.

[0071] The second electrode lead 180 is used to electrically connect the second electrode plate 112 of the electrode assembly 110 to the terminal 150. In one or more embodiments, the second electrode lead 180 may have one end welded to the uncoated portion of the second electrode plate 112 and the other end welded to the terminal 150.

[0072] Thus, when the second electrode plate 112 is the positive electrode plate as described above, the terminal 150 serves as the positive electrode.

[0073] Figure 3 is a cross-sectional view of the secondary battery 200 according to the second embodiment of the present disclosure, and Figure 4 is Figure 3 an enlarged view of part IV of

[0074] Referring to Figure 3 and Figure 4 According to the second embodiment of the present disclosure, the secondary battery 200 includes an electrode assembly 210, a can 220, a cover plate 230, a first gasket 240, a terminal 250, an insulating member 260, a first electrode lead 270, a second electrode lead 280, and a second gasket 290.

[0075] The electrode assembly 210, the first gasket 240, the terminal 250, the insulating member 260, the first electrode lead 270, and the second electrode lead 280 of the secondary battery 200 according to the second embodiment of the present disclosure are substantially the same as the electrode assembly 110, the first gasket 140, the terminal 150, the insulating member 160, the first electrode lead 170, and the second electrode lead 180 according to the first embodiment of the present disclosure, respectively. Therefore, further description of these components will be omitted, and the following description will focus on the second gasket 290.

[0076] The second gasket 290 is located between the upper end of the side portion 222 of the can 220 and the upper surface of the edge portion 231 of the cover plate 230.

[0077] Accordingly, in the secondary battery 100 according to the first embodiment of the present disclosure, the upper end of the side portion 122 of the can 120 is welded to the edge portion 131 of the cover plate 130 to tightly close the gap therebetween, while in the secondary battery 200 according to the second embodiment of the present disclosure, the gap between the upper end of the side portion 222 of the can 220 and the edge portion 231 of the cover plate 230 is filled (or substantially filled) with a second gasket 290.

[0078] The second gasket 290 is formed in an annular shape having a width in a direction substantially parallel to the upper surface of the edge portion 231 of the cover plate 230. In one or more embodiments, the first gasket 240 and the second gasket 290 may be formed separately. Accordingly, when the crimping portion 222b is formed, the second gasket 290 may not be deformed to bend radially inward (although the thickness of the second gasket 390 may be slightly compressed relative to its initial thickness), so that unwanted wrinkles and / or other deformations can be prevented or at least reduced.

[0079] The second gasket 290 may extend further radially inward than the upper end of the side portion 222 of the can 220.

[0080] In addition, the second gasket 290 may be made of, for example, polypropylene (PP), polyethylene (PE), ethylene propylene diene monomer (EPDM), nitrile butadiene rubber (NBR), or the like.

[0081] In one or more embodiments, the can 220 may be formed in a cylindrical shape. In one or more embodiments, the can 220 may include a lower portion 221 formed in a disk shape and a side portion 222 extending upward from the circumference of the lower portion 221. Since the upper portion of the can 220 is open, the electrode assembly 210 may be inserted into the can 220 together with the electrolyte through the upper portion of the can 220, and then the lower portion of the can 220 may be closed using the cover plate 230. In the can 220, the lower portion 221 may be integrally formed with the side portion 222. The can 220 may include a notch 221a configured to serve as a safety vent in the lower portion 221. Thus, when gas is generated due to abnormal operation of the secondary battery 200 and the internal pressure of the secondary battery 200 rises above a certain pressure, the pressure may cause a cut along the notch 221a to allow the notch 221a to open and discharge the gas, thereby preventing an explosion. Additionally, the can 220 may include a crimping portion 222a and a caulking portion 222b on the side portion 222. The crimping portion 222a is configured to fix the electrode assembly 210 and seat the cover plate 230, and the crimping portion 222a is formed by indenting the upper portion of the side portion 222 of the can 220 inward. The caulking portion 222b is configured to fix the cover plate 230 and is formed by bending the upper end of the side portion 222 of the can 220 inward to cover the edge portion 231 of the cover plate 230, and the second gasket 290 is between the edge portion 231 and the caulking portion 222b. The can 220 may be made of, for example, steel, steel alloy, aluminum, aluminum alloy, etc.

[0082] In addition, the cover plate 230 is coupled to the upper portion of the can 220. In one or more embodiments, in the manufacturing process of accommodating the electrode assembly 210 in the can 220, a crimping portion 222a may be formed such that the upper portion of the side portion 222 of the can 220 is recessed inward, and then the cover plate 230 may be disposed in the crimping portion 222a together with the first gasket 240. Then, a caulking portion 222b may be formed such that the upper end of the side portion 222 of the can 220 is bent inward to cover the edge portion 231 of the cover plate 230 with the second gasket 290 interposed therebetween, thereby installing the cover plate 230. Additionally, the cover plate 230 may include a step such that the upper surface of the edge portion 231 of the cover plate 230 is lower than the upper surface of the central portion 232 of the cover plate 230. In one or more embodiments, the portion connecting the edge portion 231 of the cover plate 230 to the central portion 232 may be bent obliquely (i.e., inclined) such that the edge portion 231 may be below the central portion 232, or the upper surface of the edge portion 231 of the cover plate 230 may be partially cut such that the upper surface of the edge portion 231 may be formed to be lower than the upper surface of the central portion 232. The former case is illustrated in the drawings. The height of the step in the cover plate 230 may correspond to (or substantially correspond to) the sum of the thickness of the can 220 and the thickness of the second gasket 290. Accordingly, when the upper end of the side portion 222 of the can 220 is bent inward to cover the edge portion 231 of the cover plate 230 with the second gasket 290 interposed therebetween, it prevents the upper end of the side portion 222 of the can 220 from protruding upward relative to the cover plate 230. The cover plate 230 includes a terminal hole 232a for installing the terminal 250. The terminal hole 232a may be formed through the center (or substantially the center) of the central portion 232 of the cover plate 230.

[0083] Figure 5 is a cross-sectional view of a secondary battery 300 according to a third embodiment of the present disclosure, and Figure 6 is Figure 5 an enlarged view of part VI of

[0084] Reference Figure 5 and Figure 6 , a secondary battery 300 according to a third embodiment of the present disclosure includes an electrode assembly 310, a can 320, a cover plate 330, a first gasket 340, a terminal 350, an insulating member 360, a first current collector plate 370, and a second current collector plate 380.

[0085] The electrode assembly 310 includes a first electrode plate 311, a second electrode plate 312, and a separator 313.

[0086] The first electrode plate 311 can be a negative electrode plate or a positive electrode plate. In an embodiment where the first electrode plate 311 is a negative electrode plate, the first electrode plate 311 includes a substrate material (negative electrode substrate material) having a coated portion (negative electrode coated portion) coated with an active material (negative electrode active material) and an uncoated portion (negative electrode uncoated portion) not coated with the active material (negative electrode active material). The substrate material (negative electrode substrate material) can be made of a conductive metal thin plate (e.g., copper foil, nickel foil, or mesh). The negative electrode active material can include, for example, carbon-based materials, Si, Sn, tin oxide, tin alloy composites, transition metal oxides, lithium nitrite, or metal oxides. Additionally, the negative electrode uncoated portion can be along the upper end of the first electrode plate 311.

[0087] The second electrode plate 312 can be the other of a negative electrode plate or a positive electrode plate. In an embodiment where the second electrode plate 312 is a positive electrode plate, the second electrode plate 312 includes a substrate material (positive electrode substrate material) having a coated portion (positive electrode coated portion) coated with a positive electrode active material and an uncoated portion (positive electrode uncoated portion) not coated with the active material (positive electrode active material). The substrate material (positive electrode substrate material) can be made of a conductive metal thin plate (e.g., aluminum foil or mesh). The positive electrode active material can include chalcogen compounds, such as composite metal oxides, such as LiCoO2, LiMn2O4, LiNiO2, LiNiMnO2, etc. Additionally, the positive electrode uncoated portion can be along the lower end of the second electrode plate 312.

[0088] The separator 313 is located between the first electrode plate 311 and the second electrode plate 312 and is configured to prevent a short circuit between the first electrode plate 311 and the second electrode plate 312. The separator 313 can be made of, for example, polyethylene, polypropylene, a porous copolymer of polyethylene and polypropylene, etc.

[0089] The electrode assembly 310 can be formed by sequentially stacking the first electrode plate 311, the separator 313, the second electrode plate 312, and the separator 313 and winding the first electrode plate 311, the separator 313, the second electrode plate 312, and the separator 313 into a so-called pole core shape.

[0090] The can 320 can be formed in a cylindrical shape. In one or more embodiments, the can 320 can include a lower portion 321 formed in a disk shape and a side portion 322 extending upward from the circumference of the lower portion 321. The upper portion of the can 320 is open, and the electrode assembly 310 can be inserted into the can 320 together with the electrolyte through the upper portion of the can 320. The upper portion of the can 320 can be closed using a cover plate 330.

[0091] In the can 320, the lower portion 321 can be integrally formed with the side portion 322.

[0092] The can 320 includes a terminal hole 321a for installing a terminal 350 in the lower portion 321. The terminal hole 321a may be formed through the center (or substantially the center) of the lower portion 321 of the can 320.

[0093] In addition, the can 320 may include a caulking portion 322a and a crimping portion 322b on the side portion 322. The caulking portion 322a is configured to fix the electrode assembly 310 and accommodate the cover plate 330, and the caulking portion 322a is formed by recessing the upper portion of the side portion 322 of the can 320 inward. The crimping portion 322b is configured to fix the cover plate 330, and the crimping portion 322b is formed by bending the upper end of the side portion 322 of the can 320 inward to cover the edge portion 331 of the cover plate 330.

[0094] The can 320 may be made of, for example, steel, steel alloy, aluminum, aluminum alloy, etc.

[0095] The cover plate 330 is coupled to the upper portion of the can 320.

[0096] In one or more embodiments, during the manufacturing process of accommodating the electrode assembly 310 in the can 320, the caulking portion 322a may be formed such that the upper portion of the side portion 322 of the can 320 is recessed inward, and then the cover plate 330 may be placed on the caulking portion 322a together with the first gasket 340. Then, the crimping portion 322b may be formed such that the upper end of the side portion 322 of the can 320 is bent inward to cover the edge portion 331 of the cover plate 330, thereby installing the cover plate 330.

[0097] In one or more embodiments, the upper end of the side portion 322 of the can 320 may be welded in direct contact with the edge portion 331 of the cover plate 330. In one or more embodiments, the welding may be performed by irradiating the upper end of the side portion 322 of the can 320 with a laser from above, and may be performed continuously along the edge portion 331 of the cover plate 330, i.e., in a circular manner. Accordingly, the gap between the upper end of the side portion 322 of the can 320 and the edge portion 331 of the cover plate 330 may be minimized or at least reduced, such that the edge portion 331 of the can 320 and the cover plate 330 may be tightly joined.

[0098] In addition, the cover plate 330 may include a step such that the upper surface of the edge portion 331 of the cover plate 330 is lower than the upper surface of the central portion 332 of the cover plate 330. In one or more embodiments, the portion connecting the edge portion 331 to the central portion 332 of the cover plate 330 may be bent to be inclined (i.e., slanted) such that the edge portion 331 may be positioned below the central portion 332, or the upper surface of the edge portion 331 of the cover plate 330 may be partially cut such that the upper surface of the edge portion 331 may be formed to be lower than the upper surface of the central portion 332. The former case is illustrated in the drawings. The height of the step may correspond to (or substantially correspond to) the thickness of the can 320. Accordingly, when the upper end of the side portion 322 of the can 320 is bent inward to cover the edge portion 331 of the cover plate 330, it is possible to prevent the upper end of the side portion 322 of the can 320 from protruding upward relative to the cover plate 330.

[0099] The cover plate 330 may include a notch 332a configured to serve as a safety vent at the central portion 332. Accordingly, when gas is generated due to an abnormal operation of the secondary battery 300 and the internal pressure of the secondary battery 300 rises above a certain pressure, the pressure may cause a cut along the notch 332a to allow the notch 332a to open and discharge the gas, thereby preventing an explosion.

[0100] The first gasket 340 is located between the can 320 and the cover plate 330 and is configured to prevent the electrolyte from leaking to the outside and prevent foreign substances such as moisture or dust from flowing into the inside of the can 320.

[0101] In one or more embodiments, the first gasket 340 includes a side section 341 and a lower section 342. The side section 341 is between the outer surface of the edge portion 331 of the cover plate 330 and the area between the crimping portion 322a and the caulking portion 322b of the can 320, and the lower section 342 is between the crimping portion 322a of the can 320 and the lower surface of the edge portion 331 of the cover plate 330.

[0102] The side section 341 surrounds the outer surface of the edge portion 331 of the cover plate 330. The side section 341 may not protrude higher than the upper surface of the edge portion 331 of the cover plate 330. In one or more embodiments, the upper end of the side section 341 may be at a height substantially the same as or slightly lower than the upper surface of the edge portion 331 of the cover plate 330. In the drawings, the upper end of the side section 341 is illustrated as being at the same height as the upper surface of the edge portion 331 of the cover plate 330. Accordingly, when the caulking portion 322b is formed, the upper end of the side portion 322 of the can 320 may be in close contact with the edge portion 331 of the cover plate 330 so as not to interfere with the side section 341 of the first gasket 340.

[0103] To ensure the sealing strength of the cover plate 330, the ratio T2 / T1 of the height T2 of the side section 341 to the distance T1 between the crimping part 322a and the crimping part 322b of the can 320 can be in the range of approximately 30% to approximately 60%. In one or more embodiments, the distance T1 between the crimping part 322a and the crimping part 322b of the can 320 can be about (approximate) 2.25 mm, and the height T2 of the side section 341 can be about (approximate) 1.00 mm, such that the ratio T2 / T1 is about (approximate) 44.4%.

[0104] The lower section 342 surrounds the lower surface of the edge part 331 of the cover plate 330. The thickness of the lower section 342 can be slightly compressed relative to its initial thickness during the process of forming the crimping part 322b.

[0105] To ensure the sealing strength of the cover plate 330 while avoiding interference with other components (such as the electrode assembly 310 and / or the second electrode lead 380), the ratio T3 / T1 of the total height T3 of the first gasket 340 to the distance T1 between the crimping part 322a and the crimping part 322b of the can 320 can be in the range of approximately 65% to approximately 95%. In one or more embodiments, the distance T1 between the crimping part 322a and the crimping part 322b of the can 320 can be about (approximate) 2.25 mm, and the total height T3 of the first gasket 340 can be about (approximate) 1.90 mm, such that the ratio T3 / T1 is about (approximate) 84.4%. Additionally, the ratio T2 / T3 of the height T2 of the side section 341 to the total height T3 of the first gasket 340 can be in the range of approximately 35% to approximately 70%. In one or more embodiments, the total height T3 of the first gasket 340 can be about (approximate) 1.90 mm, and the height T2 of the side section 341 can be about (approximate) 1.00 mm, such that the ratio T2 / T3 is about (approximate) 52.6%.

[0106] In the first gasket 340, the side section 341 can be integrally formed with the lower section 342.

[0107] In addition, the first gasket 340 can be made of, for example, polypropylene (PP), polyethylene (PE), ethylene propylene diene monomer (EPDM), nitrile butadiene rubber (NBR), etc.

[0108] The terminal 350 is installed in the terminal hole 321a of the can 320.

[0109] Terminal 350 can be installed, for example, by riveting. In one or more embodiments, after terminal 350 is inserted into terminal hole 321a from below the lower portion 321 of can 320, the inward insertion portion (inner portion) of terminal 350 can be deformed to have a diameter larger than the diameter of terminal hole 321a, such that the inner portion of terminal 350 is supported on the inner surface of the lower portion 321 of can 320 and fixed to the inner surface of the lower portion 321 of can 320. The outer portion of terminal 350 located outside the lower portion 321 of can 320 can be formed to have a diameter larger than the diameter of terminal hole 321a, and the outer portion of terminal 350 can be supported on the outer surface of the lower portion 321 of can 320. After terminal 350 is inserted into terminal hole 321a from above the lower portion 321 of can 320, the outward insertion portion (outer portion) of terminal 350 can be deformed to have a diameter larger than the diameter of terminal hole 321a, such that the outer portion of terminal 350 is supported on the outer surface of the lower portion 321 of can 320 and fixed to the outer surface of the lower portion 321 of can 320. The portion (inner portion) of terminal 350 located on the inner side of the lower portion 321 of can 320 can be formed to have a diameter larger than the diameter of terminal hole 321a, such that the inner portion of terminal 350 is supported on the inner surface of the lower portion 321 of can 320.

[0110] Insulating member 360 is located between can 320 and terminal 350, and is configured to electrically insulate can 320 and terminal 350 from each other, prevent electrolyte from leaking to the outside, and prevent foreign substances such as moisture or dust from flowing into the interior of can 320.

[0111] In one or more embodiments, insulating member 360 can include a portion between the outer surface of the lower portion 321 of can 320 and the outer portion of terminal 350, a portion between the inner circumferential surface of terminal hole 321a of can 320 and the portion connecting the outer portion and the inner portion of terminal 350, and a portion between the inner surface of the lower portion 321 of can 320 and the inner portion of terminal 350.

[0112] The first current collector plate 370 is used to electrically connect the first electrode plate 311 of the electrode assembly 310 to can 320. More specifically, the first current collector plate 370 can have a central portion welded to the uncoated portion of the first electrode plate 311 of the electrode assembly 310, and its edge portion can contact the side portion 322 of can 320, particularly the crimped portion 322a.

[0113] Accordingly, in an embodiment where the first electrode plate 311 is a negative electrode plate as described above, can 320 serves as the negative electrode.

[0114] The second current collector plate 380 is configured to electrically connect the second electrode plate 312 of the electrode assembly 310 to the terminal 350. In one or more embodiments, the second current collector plate 380 has one surface welded to the uncoated portion of the second electrode plate 312 and another surface welded to the inner portion of the terminal 350.

[0115] Thus, in an embodiment where the second electrode plate 312 is a positive electrode plate as described above, the terminal 350 serves as a positive electrode.

[0116] Figure 7 is a cross-sectional view of a secondary battery 400 according to a fourth embodiment of the present disclosure, and Figure 8 is Figure 7 an enlarged view of part VIII of

[0117] Referring to Figure 7 and Figure 8 , a secondary battery 400 according to a fourth embodiment of the present disclosure includes an electrode assembly 410, a can 420, a cover plate 430, a first gasket 440, a terminal 450, an insulating member 460, a first current collector plate 470, a second current collector plate 480, and a second gasket 490.

[0118] The electrode assembly 410, the first gasket 440, the terminal 450, the insulating member 460, the first current collector plate 470, and the second current collector plate 480 of the secondary battery 400 according to the fourth embodiment of the present disclosure are substantially the same as the electrode assembly 310, the first gasket 340, the terminal 350, the insulating member 360, the first current collector plate 370, and the second current collector plate 380 according to the third embodiment of the present disclosure. Accordingly, further description of these components will be omitted, and the following description will focus on the second gasket 490.

[0119] The second gasket 490 is located between the upper end of the side portion 422 of the can 420 and the upper surface of the edge portion 431 of the cover plate 430.

[0120] Thus, in the secondary battery 300 according to the third embodiment of the present disclosure, the upper end of the side portion 322 of the can 320 is welded to the edge portion 331 of the cover plate 330 to tightly seal the gap therebetween, while in the secondary battery 400 according to the fourth embodiment of the present disclosure, the gap between the upper end of the side portion 422 of the can 420 and the edge portion 431 of the cover plate 430 is filled (or substantially filled) with the second gasket 490.

[0121] The second gasket 490 has an annular shape with a width in a direction substantially parallel to the upper surface of the edge portion 431 of the cover plate 430. In one or more embodiments, the first gasket 440 and the second gasket 490 are formed separately. Thus, during the manufacturing process of forming the crimp portion 422b, the second gasket 490 does not bend or deform radially inward (although the thickness of the second gasket 490 may be slightly compressed relative to its initial thickness), such that undesired wrinkles and / or other deformations can be prevented.

[0122] The second gasket 490 may extend radially inward further than the upper end of the side portion 422 of the can 420.

[0123] In addition, the second gasket 490 may be made of, for example, polypropylene (PP), polyethylene (PE), ethylene propylene diene monomer (EPDM), nitrile butadiene rubber (NBR), etc.

[0124] In one or more embodiments, the can 420 may be formed in a cylindrical shape. In one or more embodiments, the can 420 may include a lower portion 421 formed in a disk shape and a side portion 422 extending upward from the circumference of the lower portion 421. The upper portion of the can 420 is open, and the electrode assembly 410 may be inserted into the can 420 together with the electrolyte through the upper portion of the can 420. The upper portion of the can 420 may be closed using the cover plate 430. In the can 420, the lower portion 421 may be integrally formed with the side portion 422. The can 420 includes a terminal hole 421a for mounting the terminal 450 in the lower portion 421. The terminal hole 421a may be formed through the center (or substantially the center) of the lower portion 421 of the can 420. Additionally, the can 420 may include a crimping portion 422a and a crimp portion 422b on the side portion 422. The crimping portion 422a is configured to fix the electrode assembly 410 and position the cover plate 430, and the crimping portion 422a may be formed by inwardly recessing the upper portion of the side portion 422 of the can 420. The crimp portion 422b is configured to fix the cover plate 430, and the crimp portion 422b may be formed by bending the upper end of the side portion 422 of the can 420 inward to cover the edge portion 431 of the cover plate 430, with the second gasket 490 interposed therebetween. The can 420 may be made of, for example, steel, steel alloy, aluminum, aluminum alloy, etc.

[0125] In addition, the cover plate 430 is coupled to the upper portion of the can 420. In one or more embodiments, during a manufacturing process of accommodating the electrode assembly 410 in the can 420, a crimping portion 422a may be formed such that an upper portion of the side portion 422 of the can 420 is recessed inward. The cover plate 430 may be disposed on the crimping portion 422a together with the first gasket 440, and then a crimping portion 422b may be formed such that an upper end of the side portion 422 of the can 420 is bent inward to cover an edge portion 431 of the cover plate 430, with the second gasket 490 interposed therebetween, thereby mounting the cover plate 430. Additionally, the cover plate 430 may include a step such that an upper surface of the edge portion 431 of the cover plate 430 is lower than an upper surface of a central portion 432 of the cover plate 430. In one or more embodiments, a portion connecting the edge portion 431 of the cover plate 430 to the central portion 432 may be bent to be inclined (i.e., slanted) such that the edge portion 431 may be located below the central portion 432, or an upper surface of the edge portion 431 of the cover plate 430 may be partially cut such that the upper surface of the edge portion 431 may be formed to be lower than the upper surface of the central portion 432. The former case is illustrated in the drawings. A height of the step in the cover plate 430 may correspond to (or substantially correspond to) a sum of a thickness of the can 420 and a thickness of the second gasket 490. Accordingly, during a manufacturing process in which an upper end of the side portion 422 of the can 420 is bent inward to cover the edge portion 431 of the cover plate 430 with the second gasket 490 interposed therebetween, an upper end of the side portion 422 of the can 420 is prevented from protruding upward with respect to the cover plate 430. The cover plate 430 may include a notch 432a configured to serve as a safety vent at the central portion 432. Thus, when gas is generated due to an abnormal operation of the secondary battery 400 and an internal pressure of the secondary battery 400 rises above a certain pressure, the pressure may cause a cut along the notch 432a to allow the notch 432a to open and discharge the gas, thereby preventing an explosion.

[0126] Embodiments of the present disclosure may provide a secondary battery configured to prevent a gasket from being radially bent inward or otherwise deformed inward when a crimping portion is formed in a can, thereby solving a problem of an undesired wrinkle that typically occurs due to the gasket being deformed together with the can.

[0127] The above description is only for implementing some embodiments of the secondary battery according to the present disclosure, and the present disclosure is not limited to the embodiments described above. As claimed in the claims, the technical spirit of the present disclosure includes a scope in which those skilled in the art can make various changes without departing from the gist of the present disclosure.

Claims

1. A secondary battery, comprising: an electrode assembly; a can configured to accommodate the electrode assembly, the can including an open upper portion, side portions, and a crimping portion and a caulking portion on the side portions of the can; a cover plate positioned between the crimping portion and the caulking portion of the can, the cover plate being configured to close the open upper portion of the can; a first gasket positioned between the can and an edge portion of the cover plate, the first gasket including an upper end at a height equal to or lower than an upper surface of the edge portion of the cover plate; and a terminal electrically connected to the electrode assembly.

2. The secondary battery according to claim 1, wherein an upper end of the side portion of the can is in direct contact with the upper surface of the edge portion of the cover plate.

3. The secondary battery according to claim 1, wherein the upper end of the side portion of the can is welded to the upper surface of the edge portion of the cover plate.

4. The secondary battery according to claim 1, further comprising a second gasket positioned between the upper end of the side portion of the can and the upper surface of the edge portion of the cover plate.

5. The secondary battery according to claim 4, wherein the second gasket has an annular shape, and the annular shape has a width in a direction parallel to the upper surface of the edge portion of the cover plate.

6. The secondary battery according to claim 4, wherein the second gasket extends radially inward farther than the upper end of the side portion of the can.

7. The secondary battery according to claim 4, wherein the first gasket and the second gasket are formed separately.

8. The secondary battery according to claim 1, wherein the first gasket includes: a side section positioned between a region between the crimping portion and the caulking portion of the can and an outer surface of the edge portion of the cover plate, including the upper end of the first gasket; and a lower section positioned between the crimping portion of the can and a lower surface of the edge portion of the cover plate.

9. The secondary battery according to claim 8, wherein the side section and the lower section are integrally formed.

10. The secondary battery according to claim 8, wherein a ratio of a height of the side section to a distance between the crimping portion and the caulking portion of the can is in a range of 30% to 60%.

11. The secondary battery according to claim 8, wherein a ratio of a total height of the first gasket to a distance between the crimping portion and the caulking portion of the can is in a range of 65% to 95%.

12. The secondary battery according to claim 8, wherein a ratio of a height of the side section to a total height of the first gasket is in a range of 35% to 70%.

13. The secondary battery according to claim 1, wherein the cover plate further includes a step such that the upper surface of the edge portion of the cover plate is lower than an upper surface of a central portion of the cover plate.

14. In the secondary battery according to claim 13, the step includes a portion connecting the edge portion of the cover plate to the central portion of the cover plate, and the portion is inclined.

15. The secondary battery according to claim 13, wherein a part of the upper surface of the edge portion of the cover plate is cut to form the step.

16. The secondary battery according to claim 1, wherein: the terminal is mounted in the cover plate, and the secondary battery further includes an insulating member located between the cover plate and the terminal.

17. The secondary battery according to claim 16, wherein the lower portion of the can includes a notch configured to serve as a safety vent.

18. The secondary battery according to claim 1, wherein: the terminal is mounted in the lower portion of the can, and the secondary battery further includes an insulating member located between the can and the terminal.

19. The secondary battery according to claim 18, wherein the cover plate includes a notch configured to serve as a safety vent.

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