Secondary battery

Abstract

The present invention provides a secondary battery capable of increasing durability, reinforcing the rigidity of the cap plate, and reducing cell weight. As an example, a secondary battery is disclosed comprising: an electrode assembly; a case in which the electrode assembly is received; a cap plate coupled to the case and sealing the electrode assembly; a terminal connected to the electrode assembly and exposed through the cap plate; and a projection formed in the region of the cap plate to which the terminal is coupled, the projection protruding toward the terminal.

Description

Technology Field

[0001] The present invention relates to a secondary battery capable of increasing durability, reinforcing the rigidity of the cap plate, and reducing cell weight. Background Technology

[0003] Rechargeable batteries are power storage systems that provide excellent energy density by converting electrical energy into the form of chemical energy for storage. Unlike primary batteries, which are non-rechargeable, rechargeable batteries are widely used in IT devices such as smartphones, cellular phones, laptops, and tablet PCs. Recently, interest in electric vehicles has increased due to the need to prevent environmental pollution, leading to the adoption of high-capacity rechargeable batteries in these vehicles. These rechargeable batteries require characteristics such as high density, high output, and stability.

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

[0007] The present invention provides a secondary battery capable of increasing durability, reinforcing the rigidity of the cap plate, and reducing cell weight. means of solving the problem

[0009] A secondary battery according to the present invention comprises: an electrode assembly; a case in which the electrode assembly is accommodated; a cap plate coupled to the case and sealing the electrode assembly; a terminal connected to the electrode assembly and exposed through the cap plate; and a projection protruding toward the terminal may be formed in the area of ​​the cap plate to which the terminal is coupled.

[0010] Here, the protrusion of the cap plate may be formed along the periphery of the terminal penetrating the cap plate.

[0011] And it may include a charged member interposed between the above cap plate and the above terminal.

[0012] In addition, the above-mentioned charging member may include a first projection that protrudes downward and is coupled to the inner side of the projection of the cap plate.

[0013] In addition, the first projection of the above-mentioned charging member can be coupled within the through hole of the cap plate through which the terminal passes, on the inner side of the projection of the cap plate.

[0014] In addition, the first projection of the above-mentioned charging member may include an inner surface that contacts the terminal or a sealing gasket formed around the terminal.

[0015] In addition, the above-mentioned charging member may include a second projection protruding upward along the edge.

[0016] In addition, the second projection of the above-mentioned charging member wraps around the lower side of the terminal plate exposed at the top of the terminal, thereby accommodating at least a portion of the terminal plate.

[0017] Additionally, the cap plate includes a groove corresponding to the height of the protrusion in the lower region of the protrusion, and a sealing gasket coupled to the terminal can be coupled to the groove at the lower part of the protrusion.

[0018] Additionally, the above-mentioned charged member comprises a polymer and a conductive filler, wherein the polymer comprises any one or a combination thereof selected from PPS (polyphenylene sulfide), PA (polyacetylene), PPV (polyphenylene vinylene), PPY (polypyrrole), PANI (polyaniline), PT (polythiophene) and PEDOT (poly3,4-etylenedioxythiophene), and the conductive filler may comprise any one or a combination thereof selected from carbon black, carbon fibers and carbon nanotubes. Effects of the invention

[0020] The secondary battery according to the present invention can increase durability by preventing an alloy (e.g., lithium aluminum (LiAl) alloy) from being formed on the inner surface of the case by the electrolyte, as the case is charged as a positive electrode by a high-resistance charging member, and can prevent the secondary battery from igniting by discharging energy from the charging member even if the negative electrode is short-circuited.

[0021] In addition, the secondary battery according to the present invention can secure a rigid structure against bending and deformation of the cap plate by forming a coupling protrusion on the cap plate.

[0022] In addition, the secondary battery according to the present invention can reduce the cell weight by reducing the thickness of the terminal plate. Brief explanation of the drawing

[0024] FIG. 1 is a perspective view illustrating an exemplary secondary battery according to an embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating an exemplary secondary battery shown in FIG. 1. Figure 3 is an enlarged view of part A of Figure 2. FIG. 4 is a partial perspective view illustrating an exemplary secondary battery according to an embodiment of the present invention. Fig. 5 is an exploded perspective view of Fig. 4. Specific details for implementing the invention

[0025] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0026] The embodiments of the present invention are provided to more fully explain the invention to those skilled in the art, and the following embodiments may be modified in various different forms, and the scope of the invention is not limited to the following embodiments. Rather, these embodiments are provided to make the disclosure more faithful and complete and to fully convey the spirit of the invention to those skilled in the art.

[0027] Additionally, in the drawings below, the thickness or size of each layer is exaggerated for convenience and clarity of explanation, and like reference numerals in the drawings refer to like elements. As used herein, the term "and / or" may include any one of the listed items and all combinations of one or more thereof. Furthermore, in this specification, the meaning of "may be connected" refers not only to cases where Member A and Member B are directly connected, but also to cases where Member C is interposed between Member A and Member B so that Member A and Member B are indirectly connected.

[0028] The terms used herein are for describing specific embodiments and are not intended to limit the invention. As used herein, the singular form may include the plural form unless the context clearly indicates otherwise. Additionally, as used herein, “comprise, include” and / or “comprising, including” specify the presence of the mentioned features, numbers, steps, actions, parts, elements, and / or groups thereof, and do not exclude the presence or addition of one or more other features, numbers, actions, parts, elements, and / or groups.

[0029] Although terms such as "first," "second," etc. are used in this specification to describe various components, parts, regions, layers, and / or parts, it is obvious that these components, parts, regions, layers, and / or parts should not be limited by these terms. These terms are used solely to distinguish one component, part, region, layer, or part from another region, layer, or part. Accordingly, the first component, part, region, layer, or part described below may refer to the second component, part, region, layer, or part without departing from the teachings of the present invention.

[0030] Spatial terms such as "beneath," "below," "lower," "above," and "upper" may be used to facilitate understanding of one element or feature depicted in the drawings and another element or feature. These spatial terms are intended to facilitate understanding of the invention according to various process or usage conditions of the invention and are not intended to limit the invention. For example, if an element or feature in the drawings is inverted, an element or feature described as "beneath" or "below" becomes "upper" or "on top." Therefore, "beneath" is a concept that encompasses "upper" or "below."

[0032] FIG. 1 is a perspective view illustrating an exemplary secondary battery according to an embodiment of the present invention.

[0033] In the example illustrated in FIG. 1, the secondary battery (100) may include an electrode assembly (110, 210, see FIG. 3 and FIG. 4), a first terminal (120), a second terminal (130), a case (140), and a cap assembly (150).

[0034] In some examples, the first and second terminals (120, 130) may penetrate the cap assembly (150) and be exposed to the top. In some examples, the first terminal (120) may include or be referred to as a negative terminal, and the second terminal (130) may include or be referred to as a positive terminal.

[0035] In some examples, an upper insulating member (162) may be interposed between the first terminal (120) and the cap assembly (150), and a charging member (180) may be interposed between the second terminal (130) and the cap assembly (150). Thus, the first terminal (120) and the cap assembly (150) may be electrically insulated (i.e., separated) from each other. Additionally, the second terminal (130) and the cap assembly (150) may be electrically connected (i.e., connected) to each other, and accordingly, the case (140) may be charged, for example, as a positive (or negative) electrode.

[0036] In some examples, the case (140) may be formed by a deep drawing process using a metal plate or by a bending and welding process using a metal plate, and may also be in the shape of a roughly cuboid having a space to accommodate the electrode assembly (110, 120) and to which the cap assembly (150) can be seated. In some examples, the case (140) may include a rectangular bottom portion (141) having a long side and a short side, a long side portion (142, 143) that is bent and extended from each long side of the bottom portion (141) toward the cap assembly (150), and a short side portion (144, 145) that is extended from each short side of the bottom portion (141) toward the cap assembly (150). In some examples, the case (140) may include or be referred to as a case, housing, or outer casing.

[0037] In some examples, the cap assembly (150) may include a cap plate (151), a plug (152), and a safety vent (153). This will be explained again below.

[0039] FIG. 2 is a cross-sectional view illustrating an exemplary secondary battery shown in FIG. 1. FIG. 3 is an enlarged view of section A of FIG. 2.

[0040] First, as illustrated in FIG. 2, the secondary battery (100) may include an electrode assembly (110) in which the winding axis is in a horizontal direction (i.e., a direction approximately parallel to the length direction of the cap assembly (150)). In some examples, the electrode assembly may include a stack type as well as a wound type.

[0041] The electrode assembly (110) may be formed by winding or overlapping a laminate of a first electrode plate (111), a separator (113), and a second electrode plate (112) formed as a thin plate or film. In some examples, the first electrode plate (111) may act as a negative electrode, and the second electrode plate (112) may act as a positive electrode. Of course, the opposite is also possible. In some examples, the first electrode plate (111) is formed by coating a first electrode active material, such as graphite or carbon, onto a first electrode current collector formed of a metal foil such as copper, a copper alloy, nickel, or a nickel alloy, and may include a first electrode uncoated portion (111a), which is an area where the first electrode active material is not coated. In some examples, the second electrode plate (112) is formed by applying a second electrode active material, such as a transition metal oxide, to a second electrode current collector formed of a metal foil such as aluminum or an aluminum alloy, and may include a second electrode uncoated portion (112a), which is an area where the second electrode active material is not applied. In some examples, the separator (113) is positioned between the first electrode plate (111) and the second electrode plate (112) to prevent short circuits and enable the movement of lithium ions, and may include a polyethylene, polypropylene, or a composite film of polyethylene and polypropylene. Additionally, the separator (113) may include a functional film in which an inorganic layer is coated on a porous polymer film. Additionally, the separator (113) may be replaced with an inorganic solid electrolyte, such as a sulfide-based, oxide-based, or phosphate-based electrolyte, which does not require a liquid or gel-state electrolyte. At both ends of the electrode assembly (110) as described above, a first terminal (120) and a second terminal (130) electrically connected to a first electrode plate (111) and a second electrode plate (112), respectively, may be located. In some examples, the electrode assembly (110) may be housed in a case (140) together with an electrolyte.In some examples, the electrolyte may contain a lithium salt such as LiPF6 in an organic solvent such as EC (ethylene carbonate), DMC (dimethyl carbonate), DEC (diethyl carbonate), or EMC (ethyl-methyl carbonate). Additionally, the electrolyte may be liquid or gel. In some examples, if an inorganic solid electrolyte is used, the electrolyte may be omitted.

[0043] The first terminal (120) is formed of metal and can be electrically connected to the first electrode plate (111). In some examples, the first terminal (120) may include a first current collector plate (121), a first terminal column (122), and a first terminal plate (123).

[0044] In some examples, the first current collector plate (121) may be in contact with a first electrode non-removable portion (111a) protruding from one end of the electrode assembly (110). Substantially, the first current collector plate (121) may be welded to the first electrode non-removable portion (111a). In some examples, the first current collector plate (121) may be formed in a roughly 'L' shape. In some examples, a first terminal post (122) may be integrally formed on the first current collector plate (121), or the first terminal post (122) may be separately provided and riveted and / or welded to the first current collector plate (121). In some examples, the first current collector plate (121) may be made of copper or a copper alloy.

[0045] In some examples, the first terminal post (122) may penetrate the cap plate (151), which will be described later, and extend upward for a certain length, and may be electrically connected to the first current collector plate (121) at the bottom of the cap plate (151). Additionally, in some examples, the first terminal post (122) may include a flange (122a) that extends along the longitudinal direction of the cap plate (151) to prevent the first terminal post (122) from coming loose. The first terminal post (122) may be formed integrally with the first current collector plate (121), or may be riveted and / or welded after being fitted into the first current collector plate (121). In some examples, the first terminal post (122) may be electrically insulated from the cap plate (151). In some examples, the first terminal post (122) may be made of copper, a copper alloy, aluminum, or an aluminum alloy. The first terminal plate (123) may include a hole (123a), into which a first terminal post (122) may be joined and riveted and / or welded. In some examples, the interface between the first terminal post (122) and the first terminal plate (123) exposed above may be welded to each other. For example, a laser beam may be applied to the boundary area between the first terminal post (122) and the first terminal plate (123) exposed above, so that the boundary area may be melted to each other and then cooled to be joined. In some examples, a busbar (not shown) formed of aluminum or an aluminum alloy may be welded to the first terminal plate (123) so that a plurality of secondary batteries may be connected in series or parallel.

[0047] The second terminal (130) is also formed of metal and can be electrically connected to the second electrode plate (112). In some examples, the second terminal (130) may include a second current collector plate (131), a second terminal column (132), and a second terminal plate (133). The second current collector plate (131) may come into contact with the second electrode non-contact portion (112a) protruding from one end of the electrode assembly (110). In some examples, the second current collector plate (131) may be formed in a roughly 'L' shape. In some examples, the second terminal column (132) is integrally formed with the second current collector plate (131), or the second terminal column (132) is separately provided and fitted into the second current collector plate (131) to be coupled. This second collector plate (131) can be made of aluminum or an aluminum alloy, for example, but not limited to.

[0048] The second terminal column (132) penetrates the cap plate (151), which will be described later, and extends upward for a certain length, and can also be electrically connected to the second current collector plate (131) at the bottom of the cap plate (151). The second terminal column (132) may include a flange (132a) that extends upward for a certain length while preventing the second terminal column (132) from falling out of the bottom of the cap plate (151). The area of ​​the second terminal column (132) located at the bottom of the flange (132a) may be riveted and / or welded after being fitted into the second current collector plate (131). In some examples, the second terminal column (132) may be made of aluminum or an aluminum alloy.

[0049] The second terminal plate (133) may include a hole (133a) and may be joined to the second terminal column (132) in this hole (133a). Additionally, the second terminal column (132) and the second terminal plate (133) may be riveted and / or welded to each other. In some examples, the boundary area of ​​the second terminal column (132) and the second terminal plate (133) exposed to the top may be welded to each other. For example, by providing a laser beam to the boundary area of ​​the second terminal column (132) and the second terminal plate (133) exposed to the top, the boundary area may be melted and cooled to be joined to each other. Furthermore, a number of secondary batteries may be connected in series or parallel by welding a bus bar (not shown) of aluminum or aluminum alloy to the second terminal plate (133). In some examples, the second terminal plate (133) may be electrically connected to the cap plate (151), and thus the cap plate (151) and case (140) described below may have the same polarity (e.g., positive) as the second terminal (130).

[0051] The cap assembly (150) may be attached to the case (140). In some examples, the cap assembly (150) may include or be referred to as a cap plate (151). The cap plate (151) seals the space of the case (140) and may be formed of the same material as the case (140). In some examples, the cap plate (151) may be attached to the case (140) by laser welding. In some examples, the cap plate (151) may have the same polarity as the second terminal (130) as described above, so the cap plate (151) and the case (140) may have the same polarity. In some examples, the cap plate (151) may include a through hole through which the first terminal post (122) and the second terminal post (132) each pass. In some examples, the cap plate (151) may further include an injection hole (151c) into which the electrolyte is injected and a vent hole (151d) into which a safety vent is installed. In some examples, a plug (152) may block the injection hole (151c) to prevent leakage of the electrolyte contained inside the case (140). In some examples, the plug (152) may be laser welded to the cap plate (151) after being coupled to the injection hole (151c). In some examples, a safety vent (153) may block the vent hole (151d) and release the internal high-pressure gas to the outside when the internal pressure of the case (140) rises above a set pressure. In some examples, the safety vent (153) may be laser welded to the cap plate (151) after being coupled to the vent hole (151d).

[0052] In some examples, an insulating seal gasket (161) may be interposed between the first terminal post (122) and the through hole of the cap plate (151). That is, the seal gasket (161) is formed inside the through hole of the cap plate (151), and the first terminal post (122) may protrude upward through the through hole of the seal gasket (161).

[0053] In some examples, a lower insulating member (162) may be interposed between the first collector plate (121) and the cap plate (151). Also, in some examples, an upper insulating member (162) may be interposed between the first terminal plate (123) and the cap plate (151). Thus, the first terminal (120) can be electrically insulated (separated) from the cap plate (151).

[0054] In some examples, an insulating seal gasket (171) may be interposed between the second terminal post (132) and the through hole of the cap plate (151). That is, the seal gasket (171) is formed inside the through hole of the cap plate (151), and the second terminal post (132) may protrude upward through the through hole (171a) of the seal gasket (171). In addition, in some examples, a charged member (180) may be interposed between the second terminal plate (133) and the cap plate (151). Thus, the second terminal (130) may be electrically connected to the cap plate (151).

[0055] Additionally, the cap plate (151) may each have a projection (154, 155) that protrudes upward with respect to the area where the first terminal (120) and the second terminal (130) are formed.

[0056] The first projection (154) of the cap plate (151) may be formed to correspond to the insulating member (162) of the first terminal (120). The first projection (154) may be formed along the periphery of the first terminal column (122) of the first terminal (120) and may protrude upward from the cap plate (151). Additionally, an insulating member (162) is attached to the upper part of the first projection (154), and the insulating member (162) is formed to be in contact with the seal gasket (161) to maintain airtightness. Furthermore, the insulating member (162) is formed to surround the lower side of the upper first terminal plate (123), so that the insulating member (162) attached from the first projection (154) of the cap plate (151) and the first terminal plate (123) can be firmly attached. In addition, the cap plate (151) can secure thickness in the area where the first terminal (120) is coupled through the first protrusion (154), thereby preventing deformation or bending of the cap plate (151).

[0057] Additionally, the second projection (155) of the cap plate (151) may be formed to correspond to the charging member (180) of the second terminal (130). The second projection (155) may be formed along the periphery of the second terminal column (132) of the second terminal (130) and may protrude upward from the cap plate (151). Additionally, the charging member (180) is coupled to the upper part of the second projection (155), and the charging member (180) is formed to be in contact with the seal gasket (171) to maintain airtightness. Additionally, the charging member (180) is formed to surround the lower side of the upper second terminal plate (123), so that the charging member (180) coupled from the second projection (155) of the cap plate (151) and the second terminal plate (133) can be firmly coupled.

[0058] Meanwhile, the second protrusion (155) may be formed by forging the cap plate (151). In this case, a groove corresponding to the protrusion height of the second protrusion (155) may be formed in the area of ​​the cap plate (151) located below the second protrusion (155). Additionally, when the seal gasket (171) is coupled to the groove, the fastening force to the cap plate (151) of the second terminal (130) may be improved.

[0059] In addition, the cap plate (151) can secure thickness in the area where the second terminal (130) is joined through the second protrusion (155), thereby preventing deformation or bending of the cap plate (151).

[0061] FIG. 4 is a partial perspective view illustrating an exemplary secondary battery according to an embodiment of the present invention. FIG. 5 is an exploded perspective view of FIG. 4.

[0062] As illustrated in FIGS. 4 and 5, a charging member (180) may be interposed between a cap plate (151) and a positive terminal (130). The charging member (180) may also be referred to as a resistive positive terminal. The charging member (180) may comprise a polymer and a conductive filler. For example, the charging member (180) may be formed by dispersing a conductive filler comprising at least one of carbon black, carbon fibers, and carbon nanotubes or a combination thereof in a polymer comprising at least one of PPS (polyphenylene sulfide), PA (polyacetylene), PPV (polyphenylene vinylene), PPY (polypyrrole), PANI (polyaniline), PT (polythiophene), and PEDOT (poly3,4-etylenedioxythiophene). In some examples, the electrical resistance of the charging member (180) may be between approximately 1 kΩ and approximately 1000 MΩ. Additionally, in some examples, if the polymer itself is conductive, the conductive filler may be omitted. In some examples, if the conductive filler is dispersed in the polymer, the charged member (180) may be black.

[0063] By electrically connecting the second terminal (130) and the cap plate (151) by the above-mentioned charging member (180), the cap plate (151) and the case (140) can be charged as positive. Accordingly, an alloy (e.g., lithium aluminum (LiAl) alloy) is not formed on the inner surface of the case (140) by an electrolyte containing lithium ions, so corrosion on the inner surface of the case (140) can be prevented.

[0064] In addition, since the charging member (180) has a relatively high electrical resistance, even if the first terminal (120) of the negative electrode is short-circuited to the case (140) of the positive electrode, the charging member (180) mainly consumes the short-circuit current. In some examples, when the first terminal (120) is short-circuited to the case (140) of the positive electrode, the charging member (180) mainly consumes the energy of the battery (100), thereby preventing the ignition phenomenon of the secondary battery (100).

[0065] This charging member (180) is positioned between the cap plate (151) and the second terminal (130) and may include a first projection (181) inserted into the cap plate (150) and a second projection (183) that surrounds the terminal plate (133) of the second terminal (130). Additionally, the first projection (181) of the charging member (180) may be coupled in a manner that penetrates between the seal gasket (171) and the second projection (155), and the inner surface (182) may maintain surface contact with the seal gasket (171). Thus, the sealing performance of the secondary battery (100) can be enhanced through the charging member (180) and the seal gasket (171).

[0066] Additionally, the second protrusion (183) may have a shape that protrudes upward along the edge of the charging member (180), and the second terminal plate (133) may be inserted and accommodated in the inner area of ​​the second protrusion (183). In addition, in this case, since the lower side of the second terminal plate (133) is wrapped and protected by the charging member (180), the thickness required for rigidity can be reduced compared to the conventional method. Therefore, it may be possible to reduce the weight of the secondary battery (100) by reducing the thickness of the second terminal plate (133).

[0067] In addition, in the case of the insulating member (162) described above, since it wraps around the lower side of the first terminal plate (123) in a shape corresponding to the charging member (180), it is also possible to reduce the weight of the secondary battery (100) by reducing the required thickness of the first terminal plate (123).

[0069] The above description is merely one embodiment for implementing a secondary battery according to the present invention, and the embodiments of the present invention are not limited to the above-described embodiment. The technical spirit of the present invention extends to the scope in which various modifications can be made by anyone with ordinary knowledge in the field to which the invention belongs, without departing from the gist of the invention as claimed in the following patent claims. Explanation of the symbols

[0071] 100; secondary battery 110; electrode assembly 120; 1st terminal 130; 2nd terminal 140; Case 150; Cap assembly 151; Cap plate 180; Charge member 181; 1st projection 182; inner surface 183; 2nd projection

Claims

Claim 1 An electrode assembly; a case in which the electrode assembly is accommodated; a cap plate coupled to the case and sealing the electrode assembly; a terminal connected to the electrode assembly and exposed through the cap plate; a charging member interposed between the cap plate and the terminal; and a projection formed in the area of ​​the cap plate to which the terminal is coupled, which protrudes toward the terminal, wherein the cap plate includes a groove corresponding to the height of the projection in the lower area of ​​the projection, and a seal gasket coupled to the terminal is coupled to the groove at the lower part of the projection, and the thickness of the seal gasket increases toward the lower part of the terminal. Claim 2 In claim 1, the protrusion of the cap plate is formed along the periphery of the terminal penetrating the cap plate, in a secondary battery. Claim 3 A secondary battery according to claim 1, wherein the electrical resistance of the charged member is 1 kΩ to 1000 MΩ. Claim 4 In claim 1, the secondary battery comprises a first projection that protrudes downward and is coupled to the inner side of the projection of the cap plate. Claim 5 In claim 4, the first projection of the charging member is coupled within the through hole of the cap plate through which the terminal passes, on the inner side of the projection of the cap plate, for a secondary battery. Claim 6 In claim 4, the first projection of the charging member comprises an inner surface that contacts the terminal or a sealing gasket formed around the terminal, in a secondary battery. Claim 7 In claim 1, the secondary battery comprises a second projection protruding upward along the edge of the charging member. Claim 8 In claim 7, the second projection of the charging member wraps around the lower side of the terminal plate exposed at the upper part of the terminal, thereby accommodating at least a portion of the terminal plate, for a secondary battery. Claim 9 A secondary battery according to claim 1, wherein the thickness of the seal gasket placed in the groove is greater than the thickness of the seal gasket placed in another area. Claim 10 A secondary battery according to claim 1, wherein the charging member comprises a polymer and a conductive filler, the polymer comprises any one or a combination thereof selected from PPS (polyphenylene sulfide), PA (polyacetylene), PPV (polyphenylene vinylene), PPY (polypyrrole), PANI (polyaniline), PT (polythiophene) and PEDOT (poly3,4-etylenedioxythiophene), and the conductive filler comprises any one or a combination thereof selected from carbon black, carbon fiber and carbon nanotube.

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