Rechargeable batteries and battery packs

Abstract

We provide a secondary battery that maximizes the space in which the secondary battery realizes energy. [Solution] The present invention relates to a secondary battery comprising an electrode assembly; a case having an opening on one side and housing the electrode assembly inside; a vent coupled to the opening of the case; and a first current collector plate electrically connected to the electrode assembly, wherein the first current collector plate is electrically connected to one or more of the case and the vent by welding.

Description

[Technical Field]

[0001] This application claims the benefit of the filing dates of Korean Patent Application No. 10-2021-0160477 filed with the Korean Intellectual Property Office on November 19, 2021 and Korean Patent Application No. 10-2022-0133231 filed with the Korean Intellectual Property Office on October 17, 2022, the entire contents of which are incorporated herein.

[0002] The present invention relates to a secondary battery. Specifically, the present invention relates to a secondary battery in which the space for the secondary battery to achieve energy output is maximized. [Background Art]

[0003] In general, a secondary battery, unlike non-rechargeable primary batteries, refers to a battery capable of being charged and discharged. Such secondary batteries are widely used in the field of advanced electronic devices such as mobile phones, notebook computers, and video cameras.

[0004] The stability of a secondary battery can be ensured by performing a stability test in which one surface of the secondary battery is pressed with a crimping machine to measure internal short circuits.

[0005] According to the shape of the battery case, secondary batteries can be classified into cylindrical batteries and prismatic batteries, in which an electrode assembly (or battery assembly) is housed in a cylindrical or prismatic metal case, and pouch-type batteries, in which an electrode assembly is housed in a pouch-type case made of an aluminum laminate sheet.

[0006] Further, the electrode assembly housed in the battery case is a chargeable and dischargeable power generating element having a stacked structure of positive electrode / separator / negative electrode. It is classified into a jelly-roll type electrode assembly (jelly roll) obtained by winding a long sheet-shaped positive electrode coated with an active material and a negative electrode with a separator interposed therebetween, and a stacked-type electrode assembly obtained by sequentially stacking a plurality of positive electrodes and negative electrodes of a predetermined size with separators interposed therebetween. Among them, jelly rolls have the advantages of being easy to manufacture and having high energy density per unit weight.

[0007] Conventional rechargeable batteries include beading and crimping sections in the case, and the physical space occupied by these sections, such as their width and height, limits the internal space of the case that can realize energy. [Overview of the project] [Problems that the invention aims to solve]

[0008] Focusing on the problems of the prior art described above, the present invention aims to provide a secondary battery that maximizes the space in which the secondary battery realizes energy. [Means for solving the problem]

[0009] One embodiment of the present invention provides a secondary battery comprising: an electrode assembly; a case having an opening on one side and housing the electrode assembly inside; a vent coupled to the opening of the case; and a first current collector plate electrically connected to the electrode assembly, the first current collector plate being electrically connected by welding to one or more of the case and the vent.

[0010] One embodiment of the present invention provides a secondary battery including a first welded joint to which the first current collector plate and the case are welded, and a third welded joint to which the first current collector plate and the vent are welded.

[0011] One embodiment of the present invention provides a secondary battery in which the first weld and the third weld are located along the periphery of the outer surface of the vent.

[0012] One embodiment of the present invention provides a secondary battery in which the diameter of the vent is smaller than the diameter of the inner wall of the case.

[0013] One embodiment of the present invention provides a secondary battery including a first weld where the first current collector plate and the case are welded, and a second weld where the case and the vent are welded.

[0014] One embodiment of the present invention provides a secondary battery in which the first weld and the second weld are located along the periphery of the inner wall of the case.

[0015] One embodiment of the present invention provides a secondary battery in which the diameter of the vent is smaller than the diameter of the inner wall of the case.

[0016] One embodiment of the present invention provides a secondary battery in which the case comprises a first case adjacent to the opening and having a first case thickness, and a second case having a second case thickness greater than that of the first case, wherein the thickness of the second case is three times or less that of the thickness of the first case.

[0017] One embodiment of the present invention provides a secondary battery in which the length of the first case is 5% or less of the total length of the case.

[0018] One embodiment of the present invention provides a secondary battery in which the vent includes a first vent having a first vent thickness in the direction from the center outward, and a second vent having a second vent thickness that is thinner than the first vent thickness, wherein the first vent thickness is three times or less the thickness of the second vent.

[0019] One embodiment of the present invention provides a secondary battery including a second welded joint where the contact surface of the case and the vent are welded, and a third welded joint where the contact surface of the first current collector plate and the vent are welded.

[0020] One embodiment of the present invention provides a secondary battery in which the second weld is located along the periphery of the vent, and the third weld is located along the periphery of the lower surface of the vent.

[0021] One embodiment of the present invention provides a secondary battery in which the case comprises a first case adjacent to the opening and having a first thickness, and a second case that is thicker than the first case, wherein the thickness of the second case is three times or less the thickness of the first case.

[0022] One embodiment of the present invention provides a secondary battery, wherein the length of the first case is 5% or less based on 100% of the total length of the case.

[0023] One embodiment of the present invention provides a secondary battery, wherein the vent includes a first vent having a first vent thickness from a center toward an outside direction and a second vent having a second vent thickness thinner than the first vent thickness, and the first vent thickness is 3 times or less of the second vent thickness.

[0024] One embodiment of the present invention provides a secondary battery, wherein the diameter of the vent is smaller than the diameter of the inner wall of the case.

[0025] One embodiment of the present invention provides a secondary battery, wherein the first current collector plate is bent one or more times, and an end portion thereof is positioned to face any one of the opening direction, the outward direction of the first current collector plate, and the center direction of the first current collector plate.

[0026] One embodiment of the present invention provides a secondary battery, wherein the first current collector plate includes a flat portion horizontal to the vent, and a bent portion bent to form a predetermined angle with the flat portion.

[0027] One embodiment of the present invention provides a secondary battery, wherein the bent portion is parallel to the inner wall of the case.

[0028] One embodiment of the present invention provides a secondary battery, wherein the bent portion is in contact with the inner wall of the case.

[0029] One embodiment of the present invention provides a secondary battery, wherein the bent portion includes a first bent portion bent to form a predetermined angle with the flat portion, and a second bent portion bent to form a predetermined angle with the first bent portion. Effects of the Invention

[0030] The secondary battery according to the embodiment of the present invention can maximize the space in which the secondary battery realizes energy. [Brief explanation of the drawing]

[0031] [Figure 1] This is a cross-sectional view showing a secondary battery according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view showing a secondary battery according to another embodiment of the present invention. [Figure 3] This is a cross-sectional view showing a secondary battery according to yet another embodiment of the present invention. [Figure 4] This is an enlarged view showing the contact surfaces of the case, vent, and first current collector plate according to one embodiment of the present invention. [Figure 5] This is an enlarged view of the welded portion between the vent and the first current collector plate according to one embodiment of the present invention. [Figure 6] Figure 6(a) is a perspective view showing a first current collector plate according to one embodiment of the present invention; Figure 6(b) is a perspective view showing a first current collector plate according to another embodiment of the present invention; Figure 6(c) is a perspective view showing a first current collector plate according to yet another embodiment of the present invention; Figure 6(d) is a perspective view showing a first current collector plate according to yet another embodiment of the present invention; Figure 6(e) is a perspective view showing a first current collector plate according to yet another embodiment of the present invention; and Figure 6(f) is a perspective view showing a first current collector plate according to yet another embodiment of the present invention. [Modes for carrying out the invention]

[0032] The detailed description of the present invention is intended to fully explain the invention to a person having ordinary skill in the art. Throughout the specification, where a part of the specification “includes” a component or “characterizes” a structure and shape, this does not exclude other components or other structures and shapes, unless otherwise stated, and means that other components, structures, and shapes may be included.

[0033] While the present invention may involve various transformations and have various embodiments, we will present a specific embodiment and explain it in detail in the detailed description. However, this is not intended to limit the scope of the invention by embodiment, but rather should be understood to include all transformations, equivalents, or substitutes that fall within the spirit and technical scope of the present invention.

[0034] The present invention will be described in detail below with reference to the drawings. However, the drawings are for illustrative purposes only, and the scope of the present invention is not limited by the drawings.

[0035] Figure 1 is a cross-sectional view showing a secondary battery 100a according to one embodiment of the present invention.

[0036] A secondary battery 100a according to one embodiment of the present invention includes an electrode assembly 10, a case 20, a vent 30, and a first current collector plate 51.

[0037] The electrode assembly 10 is a charge-dischargeable power generation element consisting of a laminated structure of electrodes (not shown) and separators (not shown), and may include a jelly roll type structure in which separators are interposed between long sheet-like electrodes coated with an active material and wound up.

[0038] For example, the electrodes may include a negative electrode and a positive electrode, and the negative electrode, separator, and positive electrode can be sequentially stacked to form an electrode assembly 10. Furthermore, in one embodiment of the present invention, the electrode assembly 10 can be formed by stacking multiple electrode assemblies 10, each in which a negative electrode, separator, and positive electrode are sequentially stacked.

[0039] In one embodiment of the electrode assembly 10, the electrode has an active material portion (not shown) coated with an active material along the length direction of the current collector, and plain portions (not shown) without an active material can be located on both sides of the active material portion, i.e., on both sides of the active material portion located in the length direction of the active material portion. Here, the length of the current collector may mean the direction in which the distance between the two ends is longest when the wound electrode assembly 10 is unfolded.

[0040] The active material may include a positive electrode active material and a negative electrode active material. The positive electrode active material may include lithium cobalt oxide, which has a high operating voltage and excellent capacity characteristics; lithium nickel oxide, which has high reversible capacity and facilitates the realization of large-capacity batteries; lithium nickel cobalt oxide, in which part of the nickel is replaced with cobalt; lithium nickel cobalt metal oxide, in which part of the nickel is replaced with manganese, cobalt, or aluminum; lithium manganese-based oxide, which has excellent thermal stability and is inexpensive; and lithium iron phosphorus oxide, which has excellent stability.

[0041] The negative electrode active material may be, for example, a carbon material such as crystalline carbon, amorphous carbon, carbon composite, or carbon fiber, a lithium metal, or a lithium alloy. In this case, the negative electrode active material may further contain, for example, non-graphite-based SiO (silica) or SiC (silicon carbide) for high-capacity design.

[0042] The electrode assembly 10 can be folded towards the center of the electrode assembly 10 by notching the plain sections located at both ends of the electrodes wound on the outermost side of the electrode assembly 10, opposite the winding center (or core section). Alternatively, the entire plain section wound onto the electrode assembly 10 can be notched, and the notched portion can be folded outwards from the electrode assembly 10.

[0043] In other embodiments, the electrode may include an active material portion and a blank portion on one surface of the current collector. The blank portion may be located at one or more ends of the surface of the current collector, or in an intermediate region.

[0044] Furthermore, electrode tabs (not shown) may be provided on at least a portion of the plain surface. The electrode tabs may be positioned so that a portion of them is in contact with the plain surface, and the portion protrudes in the width (W) direction of the current collector. The electrode tabs can transmit electrons collected by the current collector to an external circuit.

[0045] In a secondary battery 100a according to one embodiment of the present invention, the electrode assembly 10 may be provided with a core portion 11 formed by removing the winding core from the center. The secondary battery 100a may further include a center pin (not shown) in the core portion 11. The center pin prevents the electrode assembly 10, which is wound in a jelly roll shape, from unraveling and can act as a gas passage inside the cylindrical secondary battery 100a.

[0046] The case 20 may have a columnar structure with an internal space. The case 20 can house an electrode assembly 10 including electrodes and separators, and an electrolyte (not shown) in its internal space. One side of the case 20 may have an open structure, and the other side may have a through hole (not shown). The through hole may be circular or polygonal, and the diameter or width of the through hole may be less than the diameter of the case 20. Here, one side and the other side of the case 20 refer to the ends located at the top and bottom along the direction of gravity or the central axis of the case 20.

[0047] A case 20 according to one embodiment of the present invention may have a columnar shape with a uniform diameter or a diameter that narrows or widens along the axial direction of the case 20. A case 20 according to one embodiment of the present invention is joined to the vent 30 and the first current collector plate 51 by welding and does not include beading or crimping portions.

[0048] Therefore, in the secondary battery 100a according to one embodiment of the present invention, the gap between the electrode assembly 10 formed by the beading portion and the crimping portion and the vent 30 can be eliminated, thereby maximizing the space for realizing energy.

[0049] Furthermore, the case 20 can be set to be the same height as or higher than the height of the electrode assembly 10.

[0050] Case 20 can be made of a lightweight conductive metal material such as aluminum or an aluminum alloy.

[0051] The dimensions of case 20 may be such that the diameter of the circular parts at both ends is 30mm to 55mm and the height is 60mm to 120mm. For example, the diameter × height of the circular part of a cylindrical battery case may be 40mm × 60mm, 40mm × 80mm, 40mm × 90mm, or 40mm × 120mm.

[0052] The vent 30 is an electrically conductive thin-film structure and can be located in an opening in the case 20. In one embodiment, the diameter of the vent 30 may be the same as the internal diameter of the case 20. The vent 30 may include a first surface 31 facing the first current collector plate 51 and a second surface 32 facing the first surface 31. The side surface of the vent 30 can be in contact with the inner surface of the case 20, and the vent can be fixed to the case 20 by welding the contact surface between the side surface of the vent 30 and the case 20. Here, the side surface of the vent 30 is the surface connecting the first surface 31 and the second surface 32, and means a surface located perpendicular to the first surface 31 and the second surface 32.

[0053] The vent 30 can protrude downwards as it moves from the edge towards the center. In other words, the vent 30 can protrude in stages in the direction in which the first current collector plate 51 is located as it moves from the edge towards the center.

[0054] The vent 30 may include one or more vent notches 33 that rupture when the internal pressure of the case 20 exceeds a threshold. The vent notches 33 may be provided on one or more of the first surface 31 and second surface 32 of the vent 30. The vent notches 33 may have a continuous or discontinuous circular pattern, a linear pattern, or other pattern on the surface of the vent 30. The depth and width of the vent notches 33 are determined when the internal pressure of the case 20 exceeds 15 kgf / cm². 2 ~35 kgf / cm² 2 It can be formed to burst when it is within a certain range.

[0055] A secondary battery 100a according to one embodiment of the present invention may further include a current-blocking member (not shown). The current-blocking member is a conductive plate material member and may have through holes formed therein for discharging gas.

[0056] The current interruption member can be positioned between the vent 30 and the first current collector plate 51. The current interruption member may include a contact portion that protrudes in the direction of the first surface 31 of the vent 30 and contacts the vent 30.

[0057] A secondary battery 100a according to one embodiment of the present invention may include a first electrode terminal 40. The first electrode terminal 40 is connected to a through-hole in the battery case 20 and can be electrically connected to the electrode assembly 10.

[0058] The first electrode terminal 40 can be made of a conductive metal material. For example, the first electrode terminal 40 can be made of aluminum, but is not limited to this. Furthermore, the first electrode terminal 40 can exhibit a different polarity from the battery case 20. For example, if the battery case 20 is negative, the first electrode terminal 40 can be positive.

[0059] In one embodiment of the present invention, the secondary battery 100a may include a first terminal gasket 41 between the first electrode terminal 40 and the inner surface of the through hole, so that the first electrode terminal 40 exhibits a different polarity from the battery case 20. The first terminal gasket 41 can be made of a polymer resin having insulating and elastic properties, thereby preventing contact between the first electrode terminal 40 and the battery case 20.

[0060] The first terminal gasket 41 can be made of, for example, polypropylene, polybutylene terephthalate, polyfluoroethylene, etc., but the present invention is not limited thereto.

[0061] Figure 6(a) is a perspective view showing a first current collector plate (51_1) according to one embodiment of the present invention; Figure 6(b) is a perspective view showing a first current collector plate (51_2) according to another embodiment of the present invention; Figure 6(c) is a perspective view showing a first current collector plate (51_3) according to yet another embodiment of the present invention; Figure 6(d) is a perspective view showing a first current collector plate (51_4) according to yet another embodiment of the present invention; Figure 6(e) is a perspective view showing a first current collector plate (51_5) according to yet another embodiment of the present invention; and Figure 6(f) is a perspective view showing a first current collector plate (51_6) according to yet another embodiment of the present invention.

[0062] The first current collector plate 51 is located on one side of the electrode assembly 10, between the electrode assembly 10 and the vent 30, and can be electrically connected to the electrode assembly 10 and the vent 30. By welding the first current collector plate 51 to the plain portion of the electrode assembly 10 and the vent 30, it is possible to prevent the electrode assembly 10 from vibrating due to the gap between the electrode assembly 10 and the case 20 when the battery vibrates up and down.

[0063] The first current collector plate 51 can be bent one or more times so that its end faces the opening direction of the case 20, the outward direction of the first current collector plate 51, or the center direction of the first current collector plate 51.

[0064] In one embodiment, the first current collector plates 51_1 and 51_4 include a plate-shaped flat portion 51b that is horizontal to the vent 30, and a bent portion 51c that is bent at a predetermined angle with respect to the flat portion 51b.

[0065] The bent portion 51c may include a surface horizontal to the inner wall of the case 20. For example, the bent portion 51c can be bent at a 90-degree angle to the flat portion 51b.

[0066] The bent portion 51c can be positioned away from the inner wall of the case 20, or it can be positioned in contact with the inner wall of the case 20. When the bent portion 51c is in contact with the inner wall of the case 20, the bent portion 51c can support the first current collector plates 51_1 and 51_4 so that they do not move due to external vibrations and pressure.

[0067] In other embodiments, the first current collector plates 51_2 and 51_5 may include a plate-shaped flat portion 51b horizontal to the vent 30, a first bent portion 51c bent at a predetermined angle with respect to the flat portion 51b, and a second bent portion 51d bent at a predetermined angle with respect to the first bent portion 51c.

[0068] The first current collector plates 51_2 and 51_5 may have either the first bent portion 51c or the second bent portion 51d, which may have a surface horizontal to the inner wall of the case 20. For example, the first bent portion 51c may be bent at a 90-degree angle with the flat portion 51b, and may have a surface horizontal to the inner wall of the case 20. The second bent portion 51d may be bent at a 90-degree angle with the first bent portion 51c, so that the ends of the first current collector plates 51_2 and 51_5 face outward. That is, the second bent portion 51d may be stacked on top of the end face of the case 20.

[0069] In other embodiments, the first current collector plates 51_3 and 51_6 may include a plate-shaped flat portion 51b horizontal to the vent 30, a first bent portion 51c bent at a predetermined angle with respect to the flat portion 51b, and a second bent portion 51d bent at a predetermined angle with respect to the first bent portion 51c.

[0070] The first current collector plates 51_3 and 51_6 may have either the first bent portion 51c or the second bent portion 51d that includes a surface horizontal to the inner wall of the case 20. For example, the first bent portion 51c may be bent at a 90-degree angle with the flat portion 51b and include a surface horizontal to the inner wall of the case 20. The second bent portion 51d may be bent at a 90-degree angle with the first bent portion 51c, so that the ends of the first current collector plates 51_3 and 51_6 can be directed towards the center of the first current collector plates 51_3 and 51_6. That is, the second bent portion 51d may be stacked on top of the end face of the case 20.

[0071] Referring to Figures 6(a), 6(b), and 6(c), the first current collector plate 51 can have a disc shape. The flat portion 51b can include a plate hole 51a at a position corresponding to the core portion 11 of the electrode assembly 10.

[0072] Alternatively, referring to Figures 6(d), 6(e), and 6(f), the first current collector plates 51_4, 51_5, and 51_6 may have plate holes 51a formed at positions corresponding to the core portion 11 of the electrode assembly 10, and may include a plurality of subplates 51' extending radially from the center where the plate holes 51a are formed.

[0073] One or more of the subplates 51' may include a flat portion 51b and a folded portion 51c.

[0074] For example, the first current collection plates 51_3 and 51_4 may include eight subplates. Any one of the eight subplates may be designated as the first plate, and the second, third, and eighth plates in a clockwise direction. Here, odd-numbered subplates may have only a flat portion 51b, while even-numbered subplates may include both a flat portion 51b and a folded portion 51c. The shape of the flat portion 51b of the odd-numbered and even-numbered subplates may be the same or different.

[0075] The diameter of the plate hole 51a can be the same as or smaller than the diameter of the core portion of the electrode assembly 10.

[0076] The first current collector plate 51 may be provided with a ring-shaped second electrode terminal 60 that protrudes in the direction in which the vent 30 is located in the plate hole 51a. In other words, the second electrode terminal 60 can protrude from one surface of the first current collector plate 51 in a position corresponding to the core portion, along the periphery of the core portion, in the direction in which the vent 30 is located.

[0077] A secondary battery 100a according to one embodiment of the present invention may include welded parts 1, 2, and 3. The positions of the welded parts 1, 2, and 3 can be changed according to the shape of the vent 30 and the first current collector plate 51.

[0078] A secondary battery 100a according to one embodiment may include a first welded portion 1 where the contact surfaces of the first current collector plate 51 and the case 20 are welded, and a second welded portion 2 where the contact surfaces of the case 20 and the vent 30 are welded.

[0079] The case 20 can be provided as a cylindrical structure having a constant thickness and containing a space inside that can accommodate an electrode assembly and an electrolyte. The thickness of the case 20 can decrease towards the opening. In particular, the thickness of the case 20 can decrease by a certain length in the direction of gravity from the end of the case 20 where the opening is formed. Here, the certain length may correspond to the sum of the thicknesses of the vent 30 and the first current collector plate 51, or may be greater than the sum of the thicknesses of the vent 30 and the first current collector plate 51.

[0080] Case 20 may include a first case adjacent to the opening and having a first case thickness, and a second case having a second case thickness greater than the first case. The second case thickness may be three times or less the thickness of the first case. Preferably, the second case thickness may be two to three times the thickness of the first case.

[0081] For example, the first case thickness may be 0.5 mm or less, and the second case thickness may be 1.5 mm or less. Preferably, the first case thickness may be 0.4 mm or less, and the second case thickness may be 1.2 mm or less, and more preferably, the first case thickness may be 0.2 mm to 0.3 mm or less, and the second case thickness may be 0.4 mm to 0.9 mm.

[0082] Furthermore, the length of the first case may be 5% or less based on 100% of the total length of case 20. Preferably, the length of the first case is 2% or less, and more preferably 1.5% or less.

[0083] The first weld 1 and the second weld 2 can be welded by one of the following welding methods: seam welding, ultrasonic welding, laser welding, and cold welding. Preferably, the first weld 1 and the second weld 2 may be welded by seam welding, which is advantageous for preventing weld pinholes. Welding can be performed using seam welding.

[0084] Therefore, if the thickness of the first case welded to the vent 30 and the first current collector plate 51 exceeds 0.4 mm, electrical resistance heat cannot pass through the case 20, and heat is not transferred to the contact surface between the case 20 and the first current collector plate 51 and the contact surface between the case 20 and the vent 30. This leads to a deterioration in the quality of the first and second welds 1 and 2, and an increase in the frequency of failures in the secondary battery.

[0085] The diameter of vent 30 may be smaller than the diameter of the inner wall of case 20. More specifically, the diameter of vent 30 may be smaller than the diameter of the inner wall of the first case.

[0086] Furthermore, the first current collector plate 51 can be bent one or more times, so that the end of the first current collector plate 51 is positioned outward, that is, in the opposite direction to the center of the first current collector plate 51. The length from the center of the first current collector plate 51 to the outward-facing end (the radius of the first current collector plate 51) may be smaller than the radius of the inner wall of the first case.

[0087] The first weld 1 can be located below the second weld 2. Therefore, the first current collector plate 51 is not exposed to the outside, preventing damage to the first current collector plate 51 by external forces, and preventing a decrease in the performance of the secondary battery 100b due to increased resistance caused by damage to the first current collector plate 51.

[0088] The thickness of the bent 30 can decrease from the center outward. The bent 30 may include a first bent having a first bent thickness in the direction from the center outward, and a second bent having a second bent thickness different from that of the first bent. The second bent may be located at the edge of the bent 30, where the edge includes a constant width from the outer surface of the bent 30 toward the center.

[0089] The thickness of the first vent may be three times or less the thickness of the second vent. Preferably, the thickness of the first vent may be 1.5 to 3 times the thickness of the second vent.

[0090] For example, the first vent thickness may be 0.9 mm to 7.5 mm and the second vent thickness may be 0.6 mm to 2.5 mm. Preferably, the first vent thickness may be 0.75 mm to 4.5 mm and the second vent thickness may be 0.5 mm to 1.5 mm, and more preferably, the first vent thickness may be 0.6 mm to 2.25 mm and the second vent thickness may be 0.4 mm to 0.75 mm.

[0091] Furthermore, if the first current collector plate 51 includes a flat portion, a first bent portion, and a second bent portion, the edge of the vent 30, i.e., the width of the second vent, may correspond to the width of the second bent portion of the first current collector plate 51, or may be wider than the second bent portion 51d.

[0092] For example, the width of the second vent may be 20% or less of the radius of the vent 30. Preferably, the width of the second vent and the width of the second bent portion 51d may be 5% to 15% of the radius of the vent 30, and more preferably, the width of the second vent and the width of the second bent portion 51d may be 7% to 15% of the radius of the vent 30.

[0093] In one embodiment of the secondary battery 100a, the contact surface between the second vent and the second bent portion can be welded, and the vent 30 and the first current collector plate 51 can be welded to increase the fixing force of the first current collector plate 51, thereby increasing the durability of the secondary battery 100a against external vibrations.

[0094] Figure 2 is a cross-sectional view showing a secondary battery 100b according to another embodiment of the present invention. The secondary battery 100b according to the other embodiment may include a first weld 1 where the contact surfaces of the first current collector plate 51 and the case 20 are welded, and a third weld 3 where the contact surfaces of the first current collector plate 51 and the vent 30 are welded.

[0095] Furthermore, the diameter of the vent 30 may be smaller than the inner diameter of the case 20, the first current collector plate 51 may be bent one or more times, and the end of the first current collector plate 51 may be positioned in the direction of the opening of the case 20.

[0096] In detail, the first current collector plate 51 can be positioned between the inner surface of the case 20 and the outer surface of the vent 30. Therefore, the first weld 1 and the third weld 3 can be positioned along the periphery of the outer surface of the vent 30. In other words, the first weld 1 and the third weld 3 can be provided on the upper surface of the secondary battery 100a, that is, on the surface in the direction in which the opening is located.

[0097] In another embodiment of the secondary battery 100b, the ends of the case 20, vent 30, and first current collector plate 51 can be located on the same line. In other words, the ends of the case 20, vent 30, and first current collector plate 51 can be located on a line perpendicular to the inner wall of the case 20.

[0098] Alternatively, the ends of the case 20 and vent 30 and the first current collector plate 51 can form a step.

[0099] The ends of case 20 and vent 30 are located on the same line, and the end of the first current collector plate 51 may be located below case 20 and vent 30. Here, the lower part is defined as the direction toward the lower surface of case 20, with the upper part being the direction in which the opening in case 20 is formed and the lower part being the opposite direction.

[0100] A secondary battery 100b according to another embodiment may further include an additional weld formed by welding the first weld 1 and the third weld 3. The additional weld may be welded by an arc welding method. The additional weld may be located along the periphery of the case 20 and the vent 30. The additional weld formed by arc welding may include a weld material, which may include a conductive material. The weld material may cover the case 20, the vent 30, and the edges of the first current collector plate 51, preventing the first current collector plate 51 from being exposed to the outside.

[0101] Figure 3 is a cross-sectional view showing a secondary battery 100c according to another embodiment of the present invention. The secondary battery 100c according to another embodiment may include a second weld 2 where the contact surfaces of the case 20 and the vent 30 are welded, and a third weld 3 where the contact surfaces of the first current collector plate 51 and the vent 30 are welded.

[0102] Figure 4 is an enlarged view of the contact surfaces of the case 20, vent 30, and first current collector plate 51 of the secondary battery 100c according to yet another embodiment of the present invention, and Figure 5 is an enlarged view of the welded portion of the vent 30 and first current collector plate 51 of the secondary battery 100c according to yet another embodiment of the present invention.

[0103] In another embodiment, the secondary battery 100c may have a second weld 2 located along the outer periphery of the vent 30, and a third weld 3 located along the periphery of the edge of the lower surface of the vent 30. Here, the lower surface is the surface facing the first current collector plate 51 and refers to the first surface 31 of the vent 30.

[0104] For example, the first current collector plate 51 may be bent one or more times, with its end pointing towards the center of the first current collector plate 51, and may include a flat portion 51b, a first bent portion 51c, and a second bent portion 51d. In this case, a portion of the first bent portion 51c contacts the inner wall of the case 20. That is, the first bent portion 51c may include a surface parallel to the inner wall of the case 20.

[0105] Furthermore, the second bent portion 51d can come into contact with the first surface 31 of the vent 30, and therefore the second bent portion 51d may further include a surface parallel to the first surface 31 of the vent 30.

[0106] Alternatively, the first current collector plate 51 may be bent one or more times, with its end facing toward the center of the first current collector plate 51, and may include a flat portion 51b and a first bent portion 51c having a surface parallel to the inner wall of the case 20, the end of the first bent portion 51c facing toward the opening direction. In this case, the end of the first bent portion 51c may be in contact with and welded to the first surface 31 of the vent 30.

[0107] The case 20 can be provided as a cylindrical structure having a constant thickness and containing a space inside that can accommodate an electrode assembly and an electrolyte. The thickness of the case 20 can decrease towards the opening. In particular, the thickness of the case 20 can decrease by a certain length in the direction of gravity from the end of the case 20 where the opening is formed. Here, the certain length can correspond to the thickness of the vent 30.

[0108] The case 20 can be provided as a cylindrical structure having a constant thickness and containing a space inside that can accommodate an electrode assembly and an electrolyte. The thickness of the case 20 can decrease towards the opening. In particular, the thickness of the case 20 can decrease by a certain length in the direction of gravity from the end of the case 20 where the opening is formed. Here, the certain length may correspond to the sum of the thicknesses of the vent 30 and the first current collector plate 51, or may be greater than the sum of the thicknesses of the vent 30 and the first current collector plate 51.

[0109] Case 20 may include a first case adjacent to the opening and having a first case thickness, and a second case having a second case thickness greater than the first case. The second case thickness may be three times or less the thickness of the first case. Preferably, the second case thickness may be two to three times the thickness of the first case.

[0110] For example, the first case thickness may be 0.5 mm or less, and the second case thickness may be 1.5 mm or less. Preferably, the first case thickness may be 0.4 mm or less, and the second case thickness may be 1.2 mm or less, and more preferably, the first case thickness may be 0.2 mm to 0.3 mm or less, and the second case thickness may be 0.4 mm to 0.9 mm.

[0111] Furthermore, the length of the first case may be 5% or less based on 100% of the total length of case 20. Preferably, the length of the first case is 2% or less, and more preferably 1.5% or less.

[0112] The diameter of vent 30 may be smaller than the diameter of the inner wall of case 20. More specifically, the diameter of vent 30 may be smaller than the diameter of the inner wall of the first case.

[0113] The thickness of the bent 30 can decrease from the center outward. The bent 30 can include a first bent with the same thickness from the center outward, and a second bent with a different thickness from the first bent. The second bent can be located at the edge of the bent 30, where the edge includes a constant width from the outer surface of the bent 30 toward the center.

[0114] The thickness of the first vent may be three times or less the thickness of the second vent. Preferably, the thickness of the first vent may be 1.5 to 3 times the thickness of the second vent.

[0115] For example, the first vent thickness may be 0.9 mm to 7.5 mm and the second vent thickness may be 0.6 mm to 2.5 mm. Preferably, the first vent thickness may be 0.75 mm to 4.5 mm and the second vent thickness may be 0.5 mm to 1.5 mm, and more preferably, the first vent thickness may be 0.6 mm to 2.25 mm and the second vent thickness may be 0.4 mm to 0.75 mm.

[0116] The width of the second vent may correspond to or be wider than the width of the second bent portion 51d or the thickness of the end of the first bent portion 51c. The contact surface between the second vent and the second bent portion 51d or the first bent portion 51c can be welded (third weld). If the second vent satisfies the above numerical thickness, welding heat is transferred to the contact surface between the second vent and the second bent portion 51d or the first bent portion 51c, making it easier to weld the third weld 3.

[0117] For example, the width of the second vent may be 20% or less of the radius of the vent 30. Preferably, the width of the second vent and the width of the second bent portion 51d may be 5% to 15% of the radius of the vent 30, and more preferably, the width of the second vent and the width of the second bent portion 51d may be 7% to 15% of the radius of the vent 30.

[0118] One or more of the first weld 1, second weld 2, and third weld 3 according to one embodiment, another embodiment, and yet another embodiment may be located.

[0119] For example, if the first current collector plate 51 has a plate shape, one first weld 1, a second weld 2, and a third weld 3 may be provided. If the first current collector plate 51 includes multiple sub-plates arranged radially, multiple first welds 1, 2, and 3 welds 3 may be provided at intervals from each other.

[0120] A secondary battery 100a according to one embodiment of the present invention may further include a second current collector plate 52. The second current collector plate 52 is provided in a position opposite to the first current collector plate 51 and can be located between the electrode assembly 10 and the first electrode terminal 40. The second current collector plate 52 is made of a conductive material and can electrically connect the electrode assembly 10 and the first electrode terminal 40.

[0121] Another embodiment of the present invention provides a battery module and battery pack including a secondary battery according to the embodiment described above.

[0122] While preferred embodiments of the present invention have been described above with reference to those skilled in the art, a person skilled in the art will understand that the present invention can be modified and altered in various ways without departing from the spirit and scope of the invention as described in the following claims.

[0123] Furthermore, the present invention may include the following embodiments. [Section 1] electrode assembly; A case with one side open, in which the electrode assembly is housed; A vent connected to the opening of the case, First current collector plate electrically connected to the electrode assembly. Includes, A secondary battery in which the first current collector plate is electrically connected by welding to one or more of the case and the vent. [Section 2] The secondary battery according to item 1, comprising a first welded portion where the contact surface between the first current collector plate and the case is welded, and a third welded portion where the contact surface between the first current collector plate and the vent is welded. [Section 3] The secondary battery according to item 2, wherein the first weld and the third weld are located along the periphery of the outer surface of the vent. [Section 4] The secondary battery according to item 2, wherein the first and third welds are located along the periphery of the case adjacent to the opening. [Section 5] The secondary battery according to item 2, wherein the diameter of the vent is smaller than the diameter of the inner wall of the case. [Section 6] The secondary battery according to item 1, comprising a first welded portion where the contact surface between the first current collector plate and the case is welded, and a second welded portion where the contact surface between the case and the vent is welded. [Section 7] The secondary battery according to item 6, wherein the first weld and the second weld are located along the periphery of the inner wall of the case. [Section 8] The secondary battery according to item 6, wherein the diameter of the vent is smaller than the diameter of the inner wall of the case. [Section 9] The case includes a first case adjacent to the opening and having a first case thickness, and a second case having a second case thickness greater than that of the first case. The secondary battery according to item 6, wherein the second case thickness is no more than three times the first case thickness. [Section 10] The secondary battery according to item 9, wherein the length of the first case is 5% or less of the total length of the case. [Section 11] The vent includes a first vent having a first vent thickness in the direction from the center outward, and a second vent having a second vent thickness that is thinner than the first vent thickness. The secondary battery according to item 6, wherein the thickness of the first vent is no more than three times the thickness of the second vent. [Section 12] The secondary battery according to item 1, comprising a second welded joint where the contact surfaces of the case and the vent are welded, and a third welded joint where the contact surfaces of the first current collector plate and the vent are welded. [Section 13] The secondary battery according to item 12, wherein the second weld is located along the periphery of the vent, and the third weld is located along the periphery of the lower surface of the vent. [Section 14] The case includes a first case adjacent to the opening and having a first case thickness, and a second case having a second case thickness greater than that of the first case. The secondary battery according to item 12, wherein the second case thickness is no more than three times the first case thickness. [Section 15] The secondary battery according to item 14, wherein the length of the first case is 5% or less of the total length of the case. [Section 16] The vent includes a first vent having a first vent thickness in the direction from the center outward, and a second vent having a second vent thickness that is thinner than the first vent thickness. The secondary battery according to item 12, wherein the thickness of the first vent is no more than three times the thickness of the second vent. [Section 17] The secondary battery according to item 12, wherein the diameter of the vent is smaller than the diameter of the inner wall of the case. [Section 18] The secondary battery according to item 1, wherein the first current collector plate is bent one or more times, and its end is positioned toward one of the following directions: toward the opening, toward the outside of the first current collector plate, and toward the center of the first current collector plate. [Section 19] The secondary battery according to claim 18, wherein the first current collector plate includes a flat portion horizontal to the vent and a bent portion bent at a predetermined angle to the flat portion. [Section 20] The secondary battery according to item 19, wherein the bent portion is horizontal to the inner wall of the case. [Section 21] The secondary battery according to claim 19, wherein the bent portion includes a first bent portion bent at a predetermined angle with the flat portion, and a second bent portion bent at a predetermined angle with the first bent portion. [Section 22] A battery pack containing at least one rechargeable battery as described in any one of items 1 to 21. [Explanation of Symbols]

[0124] 100a, 100b, 100c... secondary battery 10...electrode assembly 11 ···Core section 20...cases 30 ···Bent 31...Front page 32...Second side 33 ···Bent Notch 40...1st electrode terminal 41 ···First terminal gasket 51, 51_1, 51_2, 51_3, 51_4, 51_5, 51_6... First current collection plate 51' ···Subplate 51a ···Plate hole 51b...Flat area 51c ···Folded section, first folded section 51d ···Second folding section 52 ···Second current collector plate 60...Second electrode terminal 1 ···First weld 2 ···Second weld 3 ···Third weld section

Claims

1. electrode assembly; A case with one side open, in which the electrode assembly is housed; A vent connected to the opening of the case, First current collector plate electrically connected to the electrode assembly. Includes, The first current collector plate is, The vent and the horizontal flat section, A bent portion is positioned parallel to the inner wall of the case and bent from the end of the flat portion so as to be in direct contact with the inner wall. Includes, A secondary battery, wherein the vent is electrically connected to the case and welded to the case so as to be fixed thereto.

2. The secondary battery according to claim 1, wherein the vent is welded to the case along the periphery of the outer surface of the vent.

3. The secondary battery according to claim 1, wherein the bent portion is welded to the inner wall of the case.

4. The electrode assembly includes a plain section, The plain portion has notches formed in it so that it can be bent. The secondary battery according to claim 1, wherein the first current collector plate is welded to the plain portion.

5. The vent is welded to the case along the periphery of the outer surface of the vent. The secondary battery according to claim 1, wherein the bent portion is welded to the inner wall of the case.

6. The vent is welded to the case along the periphery of the outer surface of the vent. The bent portion is welded to the inner wall of the case. The electrode assembly includes a plain section, The plain portion has notches formed in it so that it can be bent. The secondary battery according to claim 1, wherein the first current collector plate is welded to the plain portion.

7. The secondary battery according to claim 1, wherein the bent portion is welded to the vent so as to be electrically connected to the vent.

8. The secondary battery according to claim 1, wherein the bent portion is formed in an annular shape.

9. The secondary battery according to claim 1, wherein the bent portion includes a first bent portion bent at a predetermined angle with the flat portion, and a second bent portion bent at a predetermined angle with the first bent portion.

10. The vent includes a first vent having a first vent thickness in the direction from the center outward, and a second vent having a second vent thickness that is thinner than the first vent thickness. The secondary battery according to claim 1, wherein the thickness of the first vent is three times or less the thickness of the second vent.

11. The case includes a first case adjacent to the opening and having a first case thickness, and a second case having a second case thickness greater than that of the first case. The secondary battery according to claim 10, wherein the second case thickness is three times or less the thickness of the first case.

12. A battery pack comprising at least one secondary battery according to any one of claims 1 to 11.

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