Cylinder type rechargeable battery

Abstract

A cylinder-type rechargeable battery of the present invention comprises: an electrode assembly; a case including a body part and a recess part which is recessed toward the inside of the body part and of which a part is flat, and accommodating the electrode assembly; and a negative electrode current collecting plate including a base part having a portion connected to the electrode assembly and a contact part extending from an edge of the base part toward the recess part and contacting a portion formed of a flat surface in the inner surface of the case, and electrically connected to the electrode assembly.

Description

cylindrical secondary battery

[0001] The present invention relates to a cylindrical secondary battery.

[0002] Secondary batteries, unlike primary batteries that cannot be recharged, are batteries that can be charged and discharged. Low-capacity batteries with one electrode assembly packaged in a pack form are used in small portable electronic devices such as mobile phones and camcorders, and large-capacity batteries with dozens of electrode assemblies connected are widely used as power sources for driving motors in electric scooters, hybrid cars, and electric vehicles.

[0003] Secondary batteries are manufactured in various shapes, among which a cylindrical secondary battery includes an electrode assembly, a cylindrical can that accommodates the electrode assembly and an electrolyte, and a cap assembly that is joined to the upper opening of the can to seal the can and allow current generated from the electrode assembly to flow to an external device.

[0004] Among cylindrical secondary batteries, some have a structure with the negative and positive electrodes at the top. Therefore, welding may be required between the negative electrode collector and the can, and the case and collector are welded inside the secondary battery. During welding, foreign matter may be generated inside the case.

[0005] The present invention is intended to overcome the above-described conventional problems, and an object of the present invention is to provide a cylindrical secondary battery capable of preventing foreign substances from being generated inside a case.

[0006] A cylindrical secondary battery according to the present invention includes an electrode assembly, a body portion, an inlet portion that is introduced into the inside of the body portion and has a portion that is flat, a case that accommodates the electrode assembly, a base portion that has a portion that is connected to the electrode assembly, and a contact portion that extends from an edge of the base portion toward the inlet portion and comes into contact with a portion that is flat on the inner surface of the case, and includes a negative electrode current collector that is electrically connected to the electrode assembly.

[0007] The contact portion may include a first elastic portion extending from an edge of the base portion toward the inlet portion, and a second elastic portion extending from the first elastic portion, contacting a portion of the inlet portion formed in a plane, and surrounding at least a portion of the inlet portion.

[0008] The first elastic part and the second elastic part may be made of an elastically deformable material.

[0009] The negative electrode collector plate may have a first through hole positioned at the center of the negative electrode collector plate and formed to penetrate the base portion.

[0010] The negative electrode collector plate may have one or more second through holes positioned at a certain angle based on the center portion of the base portion and formed to penetrate the base portion.

[0011] The above second through hole may be in the shape of a slot.

[0012] The above negative electrode collector plate includes four second through holes, and the four second through holes can be positioned at 90-degree intervals based on the center portion of the base portion.

[0013] The above negative electrode collector plate may include one or more cut portions that are partially cut from the base portion and connected to the negative electrode plate of the electrode assembly.

[0014] The above negative electrode collector plate includes four cutouts, and the four cutouts can be positioned at 90-degree intervals based on the center of the base portion.

[0015] The above-mentioned cut portion may be a portion of the base portion cut in the shape of the alphabet U.

[0016] The inlet portion of the above case may include a first flat portion and a second flat portion positioned so that their outer surfaces face each other, and a connecting portion connecting the first flat portion and the second flat portion.

[0017] The above contact portion may be in the shape of an arc.

[0018] The cylindrical secondary battery according to the present invention can be welded from the outside by allowing the contact portion of the negative electrode current collector to contact the inlet portion of the case. This allows welding to be performed from the outside, preventing the generation of foreign substances within the case. Furthermore, the cylindrical secondary battery can also be prevented from experiencing increased resistance due to foreign substances.

[0019] Therefore, the manufacturing defect rate of cylindrical secondary batteries can be reduced, thereby improving productivity and reducing manufacturing costs.

[0020] FIG. 1 is a perspective view illustrating a cylindrical secondary battery according to one embodiment of the present invention.

[0021] Figure 2 is a cross-sectional view illustrating the cylindrical secondary battery of Figure 1.

[0022] FIG. 3 is a cross-sectional view illustrating a cylindrical secondary battery including an electrode assembly according to a modified example.

[0023] FIG. 4 is a perspective view illustrating a case and a negative electrode collector plate from a cylindrical secondary battery according to one embodiment of the present invention.

[0024] Fig. 5 is a cross-sectional view taken along line V-V' of the cylindrical secondary battery of Fig. 4.

[0025] Figure 6 is a cross-sectional perspective view illustrating the cylindrical secondary battery of Figure 5.

[0026] Fig. 7 is an enlarged cross-sectional view of area A in the cylindrical secondary battery of Fig. 5.

[0027] Fig. 8 is a plan view illustrating the negative electrode collector plate extracted from Fig. 4.

[0028] Fig. 9 is a cross-sectional view showing a negative electrode collector plate according to a modified example.

[0029] The embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. The following embodiments may be modified in various ways, and the scope of the present invention is not limited to the embodiments described below. Rather, these embodiments are provided to more faithfully and completely explain the present disclosure and fully convey the spirit of the present invention to those skilled in the art.

[0030] In addition, in the drawings below, the thickness and size of each layer are exaggerated for convenience and clarity of explanation, and the same reference numerals in the drawings indicate the same elements. As used herein, the term "and / or" includes any one and all combinations of one or more of the listed items. In addition, the meaning of "connected" in this specification means not only when member A and member B are directly connected, but also when member C is interposed between member A and member B, so that member A and member B are indirectly connected.

[0031] The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of the present invention. As used herein, the singular forms "a," "an," and "the" may include the plural forms unless the context clearly dictates otherwise. Furthermore, as used herein, the words "comprise" and "include" and / or "comprising" and "including" specify the presence of stated features, numbers, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, components, and / or groups thereof.

[0032] Although the terms first, second, etc. are used herein to describe various elements, components, regions, layers, and / or portions, it is to be understood that these elements, components, regions, layers, and / or portions are not limited by these terms. These terms are only used to distinguish one element, component, region, layer, or portion from another element, layer, or portion. Accordingly, a first element, component, region, layer, or portion described below may also refer to a second element, component, region, layer, or portion without departing from the teachings of the present invention.

[0033] In addition, terms related to space, such as "beneath," "below," "lower," "above," and "upper," may be used to facilitate understanding of one element or feature depicted in the drawings and other elements or features. These terms related to space are provided to facilitate understanding of the present invention in various process states or usage states, and are not intended to limit the present invention. For example, if an element or feature in the drawing is flipped, an element or feature described as "beneath" or "below" becomes "above" or "above." Therefore, "below" is a concept that encompasses "upper" or "below."

[0034] Hereinafter, a cylindrical secondary battery according to an embodiment of the present invention will be described with reference to the attached drawings.

[0035] Fig. 1 is a perspective view illustrating a cylindrical secondary battery according to one embodiment of the present invention, and Fig. 2 is a cross-sectional view illustrating the cylindrical secondary battery of Fig. 1. For convenience, the upper side is defined as the upper direction and the lower side is defined as the lower direction with reference to Figs. 1 and 2.

[0036] Referring to FIGS. 1 and 2, a cylindrical secondary battery (1000) according to an embodiment of the present invention may include a cylindrical case (100), an electrode assembly (200), a positive electrode collector plate (300), and a negative electrode collector plate (400A) accommodated inside the case (100), a terminal portion (500) positioned on one side of the case (100), and a cap assembly (600) positioned on the other side of the case (100).

[0037] The case (100) may include a circular belt-shaped upper surface (110), a cylindrical body portion (120) extending from the upper surface (110), and an inlet portion (130).

[0038] Since one side of the body part (120) is open, the case (100) can be formed into a cylindrical shape with one side open. The upper end of the body part (120) can be connected to the upper surface part (110). That is, the body part (120) and the upper surface part (110) can be formed as one piece.

[0039] Based on the direction shown in the drawing, the lower end of the body part (120) is open, and a cap assembly (600) is installed at the open end.

[0040] The lead-in portion (130) may be formed adjacent to the lower portion of the body portion (120). The lead-in portion (130) may be formed concavely inward from the body portion (120). The lead-in portion (130) prevents the electrode assembly (200) from being detached.

[0041] The crimping portion (134) is an end portion spaced apart from the inlet portion (130). The crimping portion (134) extends from the body portion (120) and is bent toward the inside of the case (100).

[0042] A cap assembly (600) can be placed between the crimping portion (134) and the inlet portion (130). The crimping portion (134) secures the cap assembly (600) to seal the case (100).

[0043] A detailed description of the case (100) as described above will be provided later while describing the negative electrode collector plate (400A).

[0044] The case (100) of the above-described structure may be formed of steel, steel alloy, aluminum, aluminum alloy, or an equivalent thereof, but the material is not limited thereto. Inside the case (100), an electrode assembly (200), a positive electrode collector plate (300), and a negative electrode collector plate (400A) are accommodated together with an electrolyte.

[0045] The electrolyte allows lithium ions generated by an electrochemical reaction between the first and second electrodes within the battery to move. The electrolyte may be composed of an organic solvent, such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), and / or dimethyl carbonate (DMC), and a lithium salt, such as LiPF6 or LiBF4. The electrolyte may be liquid, solid, or gel-like. Details regarding the electrolyte are as described above.

[0046] The electrode assembly (200) may be in the form of a first electrode (210), a second electrode (220), and a separator (230) interposed therebetween, rolled into a cylindrical shape. For example, the electrode assembly (200) may be rolled into the form of a jelly roll.

[0047] In this embodiment, the first electrode (210) may be an anode and the second electrode (220) may be a cathode. However, conversely, the first electrode (210) may be a cathode and the second electrode (220) may be an anode.

[0048] The first electrode (210) may be a substrate made of a thin metal plate, at least one surface of which is coated with a positive electrode active material (first active material). For example, the substrate may be aluminum (Al), and the positive electrode active material may be a transition metal oxide (LiCoO2, LiNiO2, LiMn2O4, etc.), and the details are as described above.

[0049] The edge of the first electrode (210) may have a first electrode non-coated portion (not shown), which is an area where the substrate is exposed because the positive electrode active material is not coated. In the present embodiment, the first electrode non-coated portion may be positioned toward the upper surface (110) of the case (100).

[0050] Additionally, the first electrode non-conductive portion (not shown) may protrude upward from the separator (230) and be electrically connected to the positive electrode collector plate (300). The first electrode non-conductive portion may also be referred to as a first tab, a first non-conductive portion tab, or a first substrate tab.

[0051] The second electrode (220) may be a substrate made of a thin metal plate, at least one surface of which is coated with a negative electrode active material (second active material). For example, the substrate may be copper (Cu), nickel (Ni), or an alloy of copper and nickel, and the negative electrode active material may be graphite, carbon, etc., but the details are as described above.

[0052] The edge of the second electrode (220) may have a second electrode non-coated portion (not shown), which is an area where the substrate is exposed because the negative active material is not coated. In the present embodiment, the second electrode non-coated portion may be positioned toward the bottom of the case (100).

[0053] Additionally, the second electrode non-conductive portion may protrude downward from the separator (230) and be electrically connected to the negative electrode collector plate (400A). A portion of the second electrode non-conductive portion may be electrically connected to the inlet portion (130) of the case (100). The second electrode non-conductive portion may also be referred to as a second tab, a second non-conductive portion tab, or a second substrate tab.

[0054] The separator (230) may be polyethylene (PE) or polypropylene (PP), but the details are as described above. The separator (230) can prevent electrical shorts between the first electrode (210) and the second electrode (220) and only allow the movement of lithium ions.

[0055] The electrode assembly (200) of the above-described structure is electrically connected to the positive electrode collector plate (300) and the negative electrode collector plate (400A), and can be electrically connected to the terminal portion (500) and the case (100), respectively.

[0056] The positive electrode collector plate (300) has a circular shape and can be manufactured from the same material as the first electrode (210). For example, the positive electrode collector plate (300) can be made of aluminum or an aluminum alloy.

[0057] The positive electrode collector plate (300) may be smaller in size than the upper surface (110) of the case (100). This is to prevent the positive electrode collector plate (300) from being electrically connected to the case (100).

[0058] The positive electrode collector plate (300) can be welded with its lower surface in contact with the first electrode non-conductive portion of the first electrode (210). Accordingly, the positive electrode collector plate (300) and the first electrode (210) can be electrically connected.

[0059] Additionally, the positive electrode collector plate (300) may have its upper surface welded to the second terminal (520) of the terminal portion (500) described later. Accordingly, the positive electrode collector plate (300) and the second terminal (520) may be electrically connected.

[0060] Therefore, the first electrode (210) and the second terminal (520) can be electrically connected by the positive electrode collector plate (300). That is, the positive electrode collector plate (300) becomes a passage for current flow between the first electrode (210) and the second terminal (520).

[0061] Meanwhile, although not shown in the drawing, the positive electrode collector plate (300) may include a short-circuit prevention means (not shown) such as a fuse. The positive electrode collector plate (300) may include a central region in contact with the second terminal (520), a peripheral region surrounding the central region and in contact with the first electrode non-conductive region, and a fuse region between the central region and the peripheral region.

[0062] For example, a circular slit may be formed in a circular-shaped positive electrode collector (300) to divide a central region and a peripheral region, and the fuse portion may have a smaller cross-sectional area than the central region.

[0063] The negative electrode collector plate (400A) can be electrically connected to the second electrode (220) of the electrode assembly (200). For this purpose, the negative electrode collector plate (400A) can be made of the same material as the second electrode (220). For example, the negative electrode collector plate (400A) can be made of copper.

[0064] The negative electrode collector plate (400A) may also be electrically connected to the body portion (120) of the aforementioned case (100). A portion of the negative electrode collector plate (400A) may be welded while in contact with the second electrode non-conductive portion (not shown) of the second electrode (220). Accordingly, the negative electrode collector plate (400A) and the second electrode (220) may be electrically connected. A detailed description of the negative electrode collector plate (400A) will be provided later.

[0065] The cap assembly (600) may include a cap plate (610) for sealing the case (100) and a gasket (620) for insulating between the case (100) and the cap plate (610).

[0066] The cap plate (610) may include a flat surface (612) in the shape of a disk, a first inclined surface (616) connected to the flat surface (612), and an extension surface (614) connected to the first inclined surface (616).

[0067] The flat portion (612) may be arranged approximately parallel to the negative electrode collector plate (400A). The first inclined surface (616) may extend downwardly from the edge of the flat portion (612). The extension surface (614) may extend from the edge of the inclined surface (616) and be parallel to the flat portion (612).

[0068] The extension surface (614) may further include a second inclined surface (617) extending upwardly and a joining surface (618) extending parallel to the extension surface (614) from the second inclined surface (617).

[0069] The mating surface (618) can be placed between the inlet portion (130) and the crimping portion (134) while being surrounded by a gasket (620).

[0070] Meanwhile, a notch (612a) may be on the extension surface (614). The notch (612a) may be ruptured when the pressure inside the secondary battery (1000) exceeds a certain pressure. Gas inside the secondary battery (1000) may be discharged by the rupture of the notch (612a). In other words, the notch (612a) functions as a vent.

[0071] These notches (612a) may be on one side, the other side, or both sides of the extension surface (614). Alternatively, the notches (612a) may be on one side, the other side, or both sides of the flat portion (612). In addition, there may be a plurality of notches (612a).

[0072] In another form, the cap plate (610) may not include an inclined surface (616, 617) and may be formed only of a flat surface portion (612).

[0073] The gasket (620) is placed between the lower portion of the inlet portion (130) and the crimping portion (134) and can surround the mating surface (618) of the cap plate (610). Accordingly, the gasket (620) can seal the space between the cap plate (610) and the case (100). That is, the case (100) can be sealed by the gasket (620) and the cap plate (610). The gasket (620) can surround part or all of the mating surface (618).

[0074] The side where the gasket (620) and the mating surface (618) come into contact can be defined as the inside, and the side where the gasket (620) comes into contact with the inlet portion (130) can be defined as the outside. At this time, a part of the contact portion (420A) of the negative electrode collector (400A) can be inserted between the outer upper portion of the gasket (620) and the inlet portion (130).

[0075] Accordingly, the contact portion (420A) of the negative electrode collector (400A) and the joining surface (618) of the cap plate (610) may not come into contact with each other due to the gasket (620). That is, the gasket (620) may mutually insulate the cap plate (610) and the case (100), and mutually insulate the cap plate (610) and the negative electrode collector (400A).

[0076] However, it is not limited thereto, and in another form, the joining surface (618) of the cap plate (610) may be in contact with the negative electrode collector (400A) or the case (100). Even in this form, the gasket (620) can perform the function of sealing the cap plate (610) and the case (100).

[0077] As described above, the positive electrode collector plate (300) and the negative electrode collector plate (400A) can be electrically connected to the electrode assembly. In addition, the positive electrode collector plate (300) can be electrically connected to the terminal portion (500) (or, the second terminal (520)). In addition, the negative electrode collector plate (400A) can be electrically connected to the case (100). Accordingly, the second terminal (520) can have a positive polarity, and the case (100) can have a negative polarity.

[0078] The terminal portion (500) may include, for example, a first terminal (510), a second terminal (520), and a first to third insulating members (530, 540, 550).

[0079] The shape of the first terminal (510) may be, for example, a circular plate. The first terminal (510) may be referred to as a terminal plate. The first terminal (510) may be arranged on the outside of the upper surface (110) of the case (100) and may be coupled to the second terminal (520). The first terminal (510) may be made of the same material as the second terminal (520). For example, the first terminal (510) may be made of aluminum or an aluminum alloy.

[0080] After the first terminal (510) and the second terminal (520) are joined, the upper surfaces of the first terminal (510) and the second terminal (520) can be arranged on the same plane. A bus bar can be electrically connected to the upper surface that is finally formed after the first terminal (510) and the second terminal (520) are joined.

[0081] The second terminal (520) may have a roughly cylindrical shape and may be referred to as a rivet terminal. The second terminal (520) may be riveted and connected to the first terminal (510) and the upper surface (110) of the case (100). The second terminal (520) may be made of the same material as the first terminal (510) and the positive electrode collector (300). For example, the second terminal (520) may be made of aluminum or an aluminum alloy.

[0082] The first terminal (510) and the second terminal (520) as described above can be insulated from the upper surface (110) of the case (100) by the first insulating member (530), the second insulating member (540), and the third insulating member (550).

[0083] The first insulating member (530) is disposed between the upper surface (110) of the case (100) and the second terminal (520) to insulate the upper surface (110) and the second terminal (520). That is, the first insulating member (530) may be disposed inside the case (100). The first insulating member (530) may have a shape corresponding to the stepped shape of the upper surface (110).

[0084] Meanwhile, an insulating cover (555) can be placed between the first insulating member (530) and the positive electrode collector plate (300).

[0085] The insulating cover (555) may be made of an electrically insulating material and may cover a portion of the upper surface of the positive electrode collector plate (300). For example, the insulating cover (555) may cover an area of ​​the upper surface of the positive electrode collector plate (300) except for the central portion that is in contact with the second terminal (520).

[0086] Additionally, the insulating cover (555) may extend from the upper surface of the positive electrode collector plate (300) to cover a portion of the side surface of the electrode assembly (200). At this time, a cut portion may be formed at the end of the insulating cover (555) so that the end of the insulating cover (555) can be easily bent along the side surface of the electrode assembly (200).

[0087] Accordingly, the insulating cover (555) can prevent the electrode assembly (200) (or the positive electrode collector) and the case (100) from being electrically connected. In one form, the insulating cover (555) may include an insulating tape, but is not limited thereto. In another form, the insulating cover (555) may include an injection-molded product in the shape of a cap or cup.

[0088] The first to third insulating members (530, 540, 550) described above may be composed of the same material or different materials. For example, the third insulating member (550) and the first insulating member (530) may include an insulating material having a higher heat-resistant temperature than the second insulating member (540). As another example, the second insulating member (540) may include an insulating material having a higher heat-resistant temperature than the first insulating member (530) and the third insulating member (550).

[0089] A manufacturing process of a cylindrical secondary battery (1000) according to one embodiment of the present invention as described above will be briefly described.

[0090] First, the upper surface (110) can be placed upward. Then, a support jig (not shown) for pressure support is installed inside the case (100), and pressure is applied from the outside of the case (100) to connect the second terminal (520) to the first terminal (510) and the case (100). Accordingly, the terminal portion (500) can be fixed to the case (100).

[0091] Next, the upper surface (110) can be placed downward. Then, the positive electrode collector plate (300), the electrode assembly (200), and the negative electrode collector plate (400A) can be inserted into the case (100). The positive electrode collector plate (300) and the electrode assembly (200) can be electrically connected to the first terminal (510).

[0092] Next, an inlet portion (130) can be formed after filling the inside of the case (100) with an electrolyte. The negative electrode collector plate (400A) can be electrically connected to the inlet portion (130). Next, a cap plate (610) can be placed on the inlet portion (130) via a gasket (620), and a crimping portion (134) can be created.

[0093] The detachment of the electrode assembly (200) and the negative electrode collector (400A) can be prevented by the lead-in portion (130). In addition, the cap assembly (600) can be fixed to the case (100) by the crimping portion (134).

[0094] According to the above-described process, the upper surface (110) of the case (100) may have a negative polarity, and the terminal portion (500) may have a positive polarity. That is, a secondary battery (1000) having both a positive and negative electrodes is formed on the upper side of the case (100). The above-described process order is arbitrary, and the order of each process may be changed or performed simultaneously.

[0095] Hereinafter, a cylindrical secondary battery according to another embodiment will be described with reference to the drawings. The cylindrical secondary battery of the embodiment described below may include an electrode assembly having a different shape from that of the embodiment described above.

[0096] In this embodiment, since the configuration other than the electrode assembly can be applied in the same manner as the above-described embodiment, a detailed description of the configuration other than the electrode assembly is omitted.

[0097] FIG. 3 is a cross-sectional view illustrating a cylindrical secondary battery including an electrode assembly according to a modified example.

[0098] Referring to FIG. 3, a cylindrical secondary battery (2000) according to the present embodiment includes an electrode assembly (201).

[0099] The electrode assembly (201) includes a first electrode (211), a separator (212), and a second electrode (213) that are sequentially stacked. The electrode assembly (201) may be formed by stacking the first electrode (211), the separator (212), and the second electrode (213) and then rolling them into a cylindrical shape. For example, the electrode assembly (201) may be rolled into a jelly roll shape.

[0100] A first electrode (211) includes a first electrode active portion having an active material layer (e.g., a transition metal oxide (LiCoO2, LiNiO2, LiMn2O4, etc.)) formed on at least one surface of a substrate (e.g., aluminum), and a first electrode non-conductive portion formed at an edge along the electrode active portion, which is an area where the substrate is exposed because the active material layer is not formed. An end of the active material layer may be covered with an insulating layer or the like, and the first electrode non-conductive portion is a portion formed only of a substrate on which no other layer, such as an insulating layer, is formed in addition to the active material layer.

[0101] The second electrode (213) includes a second electrode active portion having an active material layer (e.g., graphite, carbon, etc.) formed on at least one surface of a substrate (e.g., copper, nickel, or an alloy of copper and nickel), and a second electrode non-conductive portion formed at an edge along the electrode active portion, which is an area where the substrate is exposed because the active material layer is not formed. An end of the active material layer may be covered with an insulating layer, etc., and the second electrode non-conductive portion is a portion formed only of the substrate on which no other layer, such as an insulating layer or the like, is formed, in addition to the active material layer.

[0102] Meanwhile, the cylindrical secondary battery (1000) according to one embodiment of the present invention is not necessarily limited to the structure described above, and can be applied to most cylindrical secondary batteries including a negative electrode collector plate (400A) and a case (100).

[0103] Hereinafter, the case (100) and the negative electrode collector plate (400A) of the cylindrical secondary battery (1000) according to one embodiment of the present invention will be described in more detail with reference to the drawings.

[0104] FIG. 4 is a perspective view illustrating a case and a negative electrode collector in a cylindrical secondary battery according to an embodiment of the present invention, FIG. 5 is a cross-sectional view taken along line V-V' of the cylindrical secondary battery of FIG. 4, FIG. 6 is a cross-sectional perspective view illustrating the cylindrical secondary battery of FIG. 5, FIG. 7 is an enlarged cross-sectional view illustrating area A of the cylindrical secondary battery of FIG. 5, and FIG. 8 is a plan view illustrating an extract of the negative electrode collector in FIG. 4. In FIGS. 4 to 8, the cylindrical secondary battery (1000) illustrated in FIG. 2 is illustrated upside down for convenience of explanation.

[0105] Referring to FIGS. 4 to 8, in a cylindrical secondary battery (1000) according to one embodiment of the present invention, the case (100) includes a body portion (120) and an inlet portion (130) as described above.

[0106] The body (120) is formed in a cylindrical shape and accommodates an electrode assembly (200). A positive electrode collector plate (300) may be installed on one side of the body (120), and a negative electrode collector plate (400A), which will be described later, may be installed on the other side of the body (120).

[0107] The lead-in portion (130) is inserted into the inside of the body portion (120) and has a portion that is flat. After the electrode assembly (200, see FIG. 2) is inserted through the open end of the body portion (120), the lead-in portion (130) can be created by processing the case (100) through a separate process, but the method of installing the electrode assembly is not limited to this method.

[0108] The above-mentioned introduction portion (130) may include, for example, a first flat portion (131), a second flat portion (132), and a connection portion (133).

[0109] The first flat portion (131) and the second flat portion (132) are positioned so that their outer surfaces face each other. The first flat portion (131) and the second flat portion (132) may be positioned at a certain distance apart from each other in a parallel state. The first flat portion (131) and the second flat portion (132) may have a flat shape.

[0110] Welding can be performed while a portion of the negative electrode collector plate (400A) described later is in contact with either the first flat portion (131) or the second flat portion (132). The width of the first flat portion (131) and the second flat portion (132) may be approximately 0.1 mm to 1 mm, but is not limited thereto.

[0111] The connecting portion (133) connects the first flat portion (131) and the second flat portion (132). The overall shape of the inlet portion (130) may be in the shape of the alphabet U.

[0112] As described above, in a cylindrical secondary battery (1000) according to one embodiment of the present invention, the negative electrode collector plate (400A) is electrically connected to the electrode assembly (200). This negative electrode collector plate (400A) includes, for example, a base portion (410A) and a contact portion (420A).

[0113] A portion of the base portion (410A) is connected to the electrode assembly (200). The base portion (410A) may be shaped like a disk. One surface of the base portion (410A) may be fixed and electrically connected to the negative electrode plate exposed from the electrode assembly by welding while in contact with the lower surface of the electrode assembly (200).

[0114] The contact portion (420A) extends from the edge of the base portion (410A) toward the inlet portion (130) and contacts a flat portion on the inner surface of the case (100). The contact portion (420A) may have an arc shape. The contact portion (420A) may have shapes corresponding to each other so as to make seamless contact with the aforementioned inlet portion (130).

[0115] The welding method between the contact portion (420A) and the inlet portion (130) of the case (100) may be performed, for example, on the outside of the case (100) after the case (100) is sealed. More specifically, the welding may be performed at a portion of the first flat portion (131) and the second flat portion (132) of the inlet portion (130) that comes into contact with the contact portion (420A). By performing the welding on a flat surface rather than a curved surface in this way, the welding can be performed more stably.

[0116] In this embodiment, the negative electrode collector plate (400A) may not be electrically connected to the cap assembly (600) described above. However, this is not limited to the present invention, and the negative electrode collector plate (400A) may be electrically connected to the cap assembly (600), and the cap assembly (600) may have the same polarity as the second electrode (220).

[0117] Meanwhile, although not shown in the drawing, when welding is performed on the first flat portion (131), there may be four or more areas where welding is performed. For example, when there are four welding areas, each area may be located at a 90-degree angle based on the center of the base portion (410A) on the first flat portion (131). In addition, the length of welding performed on each area may be approximately 4 mm, but is not limited thereto.

[0118] Meanwhile, after the welding process is performed, it may be possible to prevent rust from occurring by performing a rust prevention process on the inlet portion (130).

[0119] In the manufacturing process of conventional cylindrical secondary batteries, the case and collector plate are welded inside the battery. Consequently, foreign matter generated during welding can accumulate inside the case. Furthermore, this foreign matter can increase resistance.

[0120] However, in the cylindrical secondary battery (1000) according to one embodiment of the present invention, the contact portion (420A) of the negative electrode collector plate (400A) can be brought into contact with the inlet portion (130) of the case (100) so that welding can be performed from the outside. Accordingly, since welding can be performed from the outside, the generation of foreign substances inside the case (100) can be prevented. In addition, the resistance of the cylindrical secondary battery (1000) can be prevented from increasing due to foreign substances.

[0121] Therefore, the manufacturing defect rate of the cylindrical secondary battery (1000) can be reduced, thereby improving productivity and reducing manufacturing costs.

[0122] Meanwhile, the first through hole (450A) may be located in the aforementioned negative electrode collector plate (400A). The first through hole (450A) is positioned at the center of the negative electrode collector plate (400A) and is formed to penetrate the base portion (410A). An electrolyte may be injected through the first through hole (450A).

[0123] In addition, one or more second through holes (460A) may be present in the aforementioned negative electrode collector plate (400A). Electrolyte may be injected through the second through holes (460A). To this end, the second through holes (460A) are positioned at a certain angle based on the center portion of the base portion (410A) and are formed to penetrate the base portion (410A).

[0124] More specifically, the negative electrode collector plate (400A) may include four second through holes (460A). In this case, the four second through holes (460A) may be positioned at 90-degree intervals based on the center portion of the base portion (410A). These second through holes (460A) may have a slot shape.

[0125] The base portion (410A) of the negative electrode collector plate (400A) is welded to the negative electrode plate of the electrode assembly. Therefore, the base portion (410A) may require a large area for welding. If the second through hole (460A) is circular rather than a long hole, the area required for welding may be insufficient, making it difficult to weld the base portion (410A) and the negative electrode plate.

[0126] However, in the cylindrical secondary battery (1000) according to one embodiment of the present invention, since the second through hole (460A) of the negative electrode current collector (400A) has a long hole shape, the area required for welding with the negative electrode plate in the base portion (410A) can be secured to the maximum extent possible.

[0127] Meanwhile, the electrolyte can be injected not only through the first through hole (450A) described above, but also through the second through hole (460A). Accordingly, the second through hole (460A) can increase the impregnation speed of the electrolyte, thereby improving impregnation properties compared to conventional cylindrical secondary batteries.

[0128] Meanwhile, the negative electrode collector plate (400A) may include one or more cutouts (470A).

[0129] The cut portion (470A) is partially cut from the base portion (410A) and is connected to the negative electrode plate of the electrode assembly. The negative electrode plate and the cut portion (470A) can be connected by welding.

[0130] The negative electrode collector plate (400A) may include four cutouts (470A). In this case, the four cutouts (470A) may be positioned at 90-degree intervals based on the center of the base portion (410A). The cutouts (470A) may be a portion of the base portion (410A) cut in the shape of the letter U.

[0131] Fig. 9 is a cross-sectional view showing a negative electrode collector plate according to a modified example.

[0132] Referring to FIG. 9, as a modified example of the negative electrode collector plate (400B), the contact portion (420B) may include a first elastic portion (421B) and a second elastic portion (422B).

[0133] The first elastic portion (421B) extends from the edge of the base portion (410A) toward the inlet portion (130).

[0134] The second elastic portion (422B) extends from the first elastic portion (421B), comes into contact with a flat portion of the inlet portion (130), and surrounds at least a portion of the inlet portion (130). More specifically, the second elastic portion (422B) may be configured to surround not only one of the first flat portion (131) and the second flat portion (132), but also the connecting portion (133).

[0135] The first elastic part (421B) and the second elastic part (422B) may be made of an elastically deformable material.

[0136] The aforementioned contact portion (420B) can be welded while simply contacting one selected from the first flat portion (131) and the second flat portion (132). However, as described above, the contact portion (420B) according to the modified example is preferentially hung on the inlet portion (130) by elastic force. Thereafter, when welding is performed from the outside of the case (100), the contact portion (420B) and the inlet portion (130) can be joined to each other.

[0137] At this time, the contact portion (420B) of the negative electrode collector plate (400B) according to the modified example is also in contact with the connection portion (133) of the lead portion (130). Therefore, welding may be performed not only at the first flat portion (131) or the second flat portion (132) but also at the connection portion (133). When welding is performed at the sunken connection portion (133), welding can be performed relatively more smoothly and accurately than when welding is performed at the first flat portion (131) or the second flat portion (132) which is a flat shape.

[0138] In addition, the contact portion (420B) of the negative electrode collector plate (400B) according to the modified example has an increased contact area with the lead portion (130) compared to the contact portion (420B) of the negative electrode collector plate (400A, see FIG. 7) described above, so that the bonding strength can be improved.

[0139] While various embodiments of the present invention have been described above, the drawings and detailed description of the invention described so far are merely illustrative of the present invention, and are used solely for the purpose of explaining the present invention and are not intended to limit the meaning or scope of the present invention as set forth in the claims. Therefore, those skilled in the art will understand that various modifications and equivalent embodiments are possible. Accordingly, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

[0140] - Explanation of symbols -

[0141] 1000, 2000: Cylindrical secondary battery

[0142] 100: Case 120: Body

[0143] 130: Inlet 131: First flat section

[0144] 132: Second flat section 133: Connection section

[0145] 200: Electrode assembly 300: Positive current collector

[0146] 400A, 400B: Negative collector plate 410A: Base

[0147] 420A, 420B: Contact portion 421B: First elastic portion

[0148] 422B: Second elastic member 450A: First through hole

[0149] 460A: Second through hole 470A: Cutout

Claims

1. Electrode assembly; A case including a body portion and an inlet portion that is introduced into the inside of the body portion and has a portion that is flat, and that accommodates the electrode assembly; and A cylindrical secondary battery comprising a base portion connected to the electrode assembly, a contact portion extending from an edge of the base portion toward the inlet portion and contacting a portion formed of the plane on the inner surface of the case, and a negative electrode collector electrically connected to the electrode assembly.

2. In paragraph 1, The above contact part, A first elastic member extending from the edge of the base member toward the inlet member; and A cylindrical secondary battery including a second elastic member extending from the first elastic member, contacting a portion formed in a plane at the inlet portion, and surrounding at least a portion of the inlet portion.

3. In paragraph 2, A cylindrical secondary battery in which the first elastic portion and the second elastic portion are made of an elastically deformable material.

4. In paragraph 1, A cylindrical secondary battery having a first through hole positioned at the center of the negative electrode collector plate and formed to penetrate the base portion.

5. In paragraph 1, A cylindrical secondary battery having at least one second through hole positioned at a certain angle based on the center portion of the base portion and formed to penetrate the base portion.

6. In paragraph 5, The above second through hole is a cylindrical secondary battery having a slot shape.

7. In paragraph 5, A cylindrical secondary battery in which the negative electrode collector plate includes four second through holes, and the four second through holes are positioned at 90-degree intervals based on the center portion of the base portion.

8. In paragraph 1, The above negative electrode collector plate is, A cylindrical secondary battery comprising one or more cut portions cut from the base portion and connected to the negative plate of the electrode assembly.

9. In paragraph 8, A cylindrical secondary battery in which the negative electrode collector plate includes four cutouts, and the four cutouts are positioned at 90-degree intervals based on the center of the base portion.

10. In paragraph 8, The above-mentioned cut portion is a cylindrical secondary battery in which a portion of the base portion is cut in the shape of the alphabet U.

11. In paragraph 1, The inlet portion of the above case is, A first flat portion and a second flat portion positioned so that their outer surfaces face each other; and A cylindrical secondary battery comprising a connecting portion connecting the first flat portion and the second flat portion.

12. In paragraph 1, The above contact portion is a cylindrical secondary battery having an arc shape.

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