Secondary battery

Abstract

The present disclosure relates to a secondary battery. The technical problem to be solved is to provide a secondary battery, wherein a separate terminal is configured to be connected by welding, thereby reducing the overall thickness of the terminal compared to the prior art, and thus ensuring a relatively large battery capacity. To this end, the present disclosure provides a secondary battery comprising: an electrode assembly having a first electrode plate, a separator, and a second electrode plate; a cylindrical case in which the electrode assembly is accommodated; and a terminal coupled to a through-hole formed in the upper surface of the case. The terminal comprises: a first terminal plate coupled to the through-hole of the case; and a second terminal plate and a third terminal plate coupled to one side and the other side of the first terminal plate, respectively. The first terminal plate and the second terminal plate are coupled to each other by welding, and the first terminal plate and the third terminal plate are coupled to each other by welding.

Description

secondary batteries

[0001] This disclosure relates to a secondary battery.

[0002] Secondary batteries (rechargeable batteries) are rechargeable, unlike primary batteries, which are non-rechargeable. Low-capacity secondary batteries are used in small, portable electronic devices such as smartphones, feature phones, tablet computers, laptops, digital cameras, and camcorders, while large-capacity secondary batteries are widely used for motor drive and power storage in hybrid and electric vehicles.

[0003] These secondary batteries can be classified into cylindrical, square, and pouch types depending on their external shape. Among these, cylindrical secondary batteries may typically include an electrode assembly, a can, a cap assembly, etc.

[0004] Additionally, the cell capacity of a secondary battery can vary depending on the structure of its internal components and the bonding structure of those components. For example, the size of the rivets can affect the cell capacity. The purpose of these rivets is to separate the terminals and prevent leakage. Therefore, it is important to achieve slimness while satisfying the fundamental purpose of cell components such as the rivets.

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

[0006] The present disclosure provides a secondary battery in which the overall thickness of the terminal is reduced compared to the conventional one by forming a separation terminal connected by welding.

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

[0008] According to one embodiment of the present invention for solving the above technical problem, a secondary battery includes an electrode assembly having a first electrode plate, a separator, and a second electrode plate; a cylindrical case in which the electrode assembly is accommodated; and a terminal coupled to a through hole in an upper surface of the case, wherein the terminal includes a first terminal plate coupled to the through hole of the case, and a second terminal plate and a third terminal plate coupled to one side and the other side of the first terminal plate, respectively, and the first terminal plate and the second terminal plate, and the first terminal plate and the third terminal plate, can be respectively coupled by welding.

[0009] The first terminal plate and the second terminal plate can be welded inside the case.

[0010] The first terminal plate and the third terminal plate can be welded on the outside of the case.

[0011] It may further include a first insulating member interposed between the first terminal plate and the through hole of the case.

[0012] It may further include a second insulating member interposed between the second terminal plate and the lower surface of the case.

[0013] It may further include a third insulating member interposed between the third terminal plate and the upper surface of the case.

[0014] The first insulating member may be formed of a material having the same or higher heat resistance as the second insulating member and the third insulating member.

[0015] The case includes a terminal groove formed in a central area of ​​the upper surface of the case centered around the through hole, and the third terminal plate and the third insulating member can be seated in the terminal groove.

[0016] The case includes a crimping portion formed along the end of the terminal groove, and the crimping portion can be formed in a shape that wraps around the edge of the third terminal plate.

[0017] A gasket may further be included between the crimping portion and the third terminal plate.

[0018] The above gasket may be formed in a shape that surrounds the side and upper edges of the third terminal plate.

[0019] A circular hole may be formed in the center of each of the gasket, the first insulating member, the second insulating member, and the third insulating member.

[0020] The above gasket may protrude toward the center from the end of the above crimping portion.

[0021] The diameter of the second terminal plate may be equal to or smaller than the outer diameter of the second insulating member.

[0022] The diameter of the third terminal plate may be the same as the outer diameter of the third insulating member.

[0023] The diameter of the second terminal plate and the third terminal plate may be smaller than the outer diameter of the second insulating member and the third insulating member.

[0024] At least one of the second insulating member and the third insulating member may be formed of a heat-sealing material.

[0025] At least one pair of the second terminal plate and the second insulating member, and the third terminal plate and the third insulating member can be joined by a heat-fusion method.

[0026] A circular hole may be formed in the center of each of the first insulating member, the second insulating member, and the third insulating member.

[0027] The thickness of each of the second terminal plate and the third terminal plate may be thinner than or equal to the thickness of each of the second insulating member and the third insulating member.

[0028] According to the present invention, by forming a separation terminal connected by welding, the overall thickness of the terminal can be reduced compared to the conventional one, thereby securing a relatively large battery capacity.

[0029] However, the effects that can be obtained through the present invention are not limited to the effects described above, and other technical effects not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0030] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0031] Figure 1 is a cross-sectional view of the upper side of a secondary battery according to an embodiment of the present invention.

[0032] Figure 2 is an enlarged view of part A of Figure 1.

[0033] Figure 3 is an enlarged view of the upper side of a secondary battery according to another embodiment of the present invention.

[0034] Figure 4 is a cross-sectional view of the upper side of a secondary battery according to various embodiments of the present invention.

[0035] Figure 5 is an enlarged view of part B of Figure 4.

[0036] Figure 6 is an enlarged view of part B of Figure 4 after fusion.

[0037] Figures 7a to 7c are cross-sectional views for explaining the bonding process of Figure 4.

[0038] FIG. 8a and FIG. 8b are drawings schematically showing the configuration of a secondary battery pack according to an embodiment of the present invention.

[0039] Figure 9a is a perspective view illustrating an exemplary body.

[0040] FIG. 9b is a drawing for explaining a vehicle including the secondary battery pack of FIG. 8.

[0041] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms or words used in this specification and claims should not be interpreted as limited to their typical or dictionary meanings, and should be interpreted with meanings and concepts that conform to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of a term to best explain his or her own invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as substitutes for them at the time of filing this application.

[0042] Additionally, when used herein, the terms "comprise", "include" and / or "comprising", "including" specify the presence of stated features, numbers, steps, operations, elements, elements and / or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, elements and / or groups thereof.

[0043] Additionally, to facilitate understanding of the invention, the attached drawings are not drawn to scale and some components may be exaggerated in size. Furthermore, identical components may be assigned the same reference numbers in different embodiments.

[0044] The statement that two compared objects are "identical" means "substantially identical." Therefore, "substantially identical" may include deviations considered low in the art, such as deviations of less than 5%. Furthermore, uniformity of a parameter over a given region may imply uniformity on average.

[0045] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0046] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0047] Any configuration being placed "on (or under)" or "above (or below)" a component may mean not only that any configuration is placed in contact with the upper surface (or lower surface) of said component, but also that other configurations may intervene between said component and any configuration placed on (or below) said component.

[0048] Additionally, when it is described that a component is "connected," "coupled," or "connected" to another component, it should be understood that the components may be directly connected or connected to each other, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through another component. Furthermore, when it is said that a part is electrically coupled to another part, this includes not only cases where they are directly connected, but also cases where they are connected with another element in between.

[0049] When reference is made throughout the specification to "A and / or B," this means A, B, or A and B, unless otherwise stated. In other words, "and / or" includes all or any combination of the listed items. When reference is made to "C through D," this means C or more and D or less, unless otherwise stated.

[0050] The terminology used herein is for the purpose of describing embodiments of the present disclosure and is not intended to be limiting of the present disclosure.

[0051] In exemplary embodiments of cylindrical batteries according to the embodiments of the present disclosure, one of the cylindrical batteries is selected and the selected battery is described as having a general structure, and in the case of a generally applicable technology, the general structure of the cylindrical battery is described.

[0052] FIG. 1 is a cross-sectional view of the upper side of a secondary battery according to an embodiment of the present invention, and FIG. 2 is an enlarged view of part A of FIG. 1.

[0053] Referring to FIGS. 1 and 2, a secondary battery (100) may include an electrode assembly (110), a cylindrical case (120) that accommodates the electrode assembly (110) and an electrolyte therein, a terminal (130) installed in a through hole (122a) provided at one end of the case (120), and an insulating member (140) interposed between the terminal (130) and the case (120). In addition, the secondary battery (100) may include a cap plate (not shown) that seals an opening at the other end of the case (120).

[0054] The electrode assembly (110) may include a separator, a first electrode plate (111) positioned with the separator between them, and a second electrode plate (not shown), and may be wound in a jelly-roll shape.

[0055] The first electrode plate (111) may include a first substrate and a first active material layer positioned on the first substrate. A first non-conductive portion of the first substrate, where the first active material layer is not positioned, may extend outward, and the first electrode plate (111) may be electrically connected to a terminal (130) via a first current collector plate (160). The first current collector plate (160) and the first electrode plate (111) may be electrically and mechanically connected to each other by welding.

[0056] The second electrode plate may include a second substrate and a second active material layer positioned on the second substrate. A second non-conductive portion of the second substrate, where the second active material layer is not positioned, may extend outward, and the second electrode plate may be electrically connected to the case (120) via the second current collector plate.

[0057] The first electrode plate (111) and the second electrode plate may extend in opposite directions. The first electrode plate (111) may protrude in one direction of the case (120), for example, in the upward direction in FIGS. 1 and 2 , and the second electrode plate may protrude in the other direction of the case (120).

[0058] The first electrode plate (111) can function as an anode. In this case, the first substrate can be composed of, for example, aluminum foil, and the first active material layer can include, for example, a transition metal oxide. The second electrode plate can function as an anode. In this case, the second substrate can be composed of, for example, copper foil or nickel foil, and the second active material layer can include, for example, graphite.

[0059] The separator functions to prevent short circuiting between the first electrode plate (111) and the second electrode plate while allowing the movement of lithium ions. The separator may be composed of, for example, a polyethylene film, a polypropylene film, a polyethylene-polypropylene film, etc.

[0060] The case (120) can accommodate the electrode assembly (110) and the electrolyte, and can form the outer shape of the secondary battery (100). The case (120) can include a body part (121) having a roughly cylindrical shape, and an upper surface (122) connected to the upper side of the body part (121). That is, the upper surface (122) of the case (120) can be formed in a circular shape, and the body part (121) can extend downward by a certain length from the edge of the upper surface (122). The body part (121) and the upper surface (122) can be formed as an integral body.

[0061] However, the present invention is not limited thereto, and the can may be configured in various shapes such as a square shape or a pouch shape. In addition, the can may be configured of a metal such as aluminum, an aluminum alloy, nickel-plated steel, or a laminate film or plastic forming a pouch.

[0062] Meanwhile, in some examples, a compound capable of reversible intercalation and deintercalation of lithium (a lithiated intercalation compound) may be used as the cathode active material. Specifically, one or more of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof may be used.

[0063] The above composite oxide may be a lithium transition metal composite oxide, and specific examples thereof include lithium nickel-based oxide, lithium cobalt-based oxide, lithium manganese-based oxide, lithium iron phosphate-based compound, cobalt-free nickel-manganese-based oxide, or a combination thereof.

[0064] As an example, a compound represented by any one of the following chemical formulas may be used: Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-cD c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b X c About 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b X c About 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3(0≤f≤2); Li a FePO4(0.90≤a≤1.8).

[0065] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; L 1 is Mn, Al or a combination thereof.

[0066] A positive electrode for a lithium secondary battery may include a current collector and a positive electrode active material layer formed on the current collector. The positive electrode active material layer includes a positive electrode active material and may further include a binder and / or a conductive material.

[0067] The content of the positive electrode active material may be 90 wt% to 99.5 wt% with respect to 100 wt% of the positive electrode active material layer, and the contents of the binder and conductive material may be 0.5 wt% to 5 wt%, respectively, with respect to 100 wt% of the positive electrode active material layer.

[0068] Al may be used as the above current collector, but is not limited thereto.

[0069] The negative electrode active material includes a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0070] The material capable of reversibly intercalating / deintercalating the lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0071] As the material capable of doping and dedoping the lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used. The Si-based negative electrode active material is silicon, a silicon-carbon composite, SiO x (0 < x < 2), Si-based alloys or combinations thereof.

[0072] The above silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles.

[0073] The silicon-carbon composite may further comprise crystalline carbon. For example, the silicon-carbon composite may comprise a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer positioned on the surface of the core.

[0074] A negative electrode for a lithium secondary battery includes a current collector and a negative electrode active material layer positioned on the current collector. The negative electrode active material layer includes a negative electrode active material and may further include a binder and / or a conductive material.

[0075] For example, the negative electrode active material layer may include 90 to 99 wt% of the negative electrode active material, 0.5 to 5 wt% of the binder, and 0 to 5 wt% of the conductive material.

[0076] The above binder may be a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof. When an aqueous binder is used as the negative electrode binder, a cellulose-based compound capable of imparting viscosity may be further included.

[0077] The negative electrode current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and a combination thereof.

[0078] The electrolyte for a lithium secondary battery contains a non-aqueous organic solvent and a lithium salt.

[0079] The above non-aqueous organic solvent acts as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0080] The above non-aqueous organic solvent may be a carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvent, an aprotic solvent, or a combination thereof, and may be used alone or in combination of two or more thereof.

[0081] Additionally, when using a carbonate solvent, a mixture of cyclic carbonate and chain carbonate can be used.

[0082] Depending on the type of lithium secondary battery, a separator may be present between the positive and negative electrodes. Such separators may be polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film comprising two or more layers of these materials.

[0083] The above separator may include a porous substrate and a coating layer comprising an organic material, an inorganic material, or a combination thereof, positioned on one or both sides of the porous substrate.

[0084] The organic material may include a polyvinylidene fluoride polymer or a (meth)acrylic polymer.

[0085] The above inorganic material may include inorganic particles selected from, but not limited to, Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0086] The organic and inorganic substances may be mixed and present in one coating layer, or a coating layer including an organic substance and a coating layer including an inorganic substance may be present in a laminated form.

[0087] Referring to FIG. 2, the upper surface (122) of the case (120) may include a through hole (122a) formed in the central region, and a terminal groove (122b) formed on the lower surface of the upper surface (122) with a step centered around the through hole (122a). That is, the through hole (122a) may be provided within the terminal groove (122b). In addition, the upper surface (122) of the case (120) may include a crimping portion (122c) formed on the upper surface of the upper surface (122) with the through hole (122a) as the center. The crimping portion (122c) may be formed along the end of the terminal groove (122b).

[0088] In some examples, the terminal (130) may be formed of a plurality of separable plates including a first terminal plate (131), a second terminal plate (132), and a third terminal plate (133). At this time, the first terminal plate (131) may be coupled to the through hole (122a), and the second terminal plate (132) and the third terminal plate (133) may be coupled to one side and the other side of the first terminal plate (131), respectively.

[0089] The third terminal plate (133) may be coupled to the other side of the first terminal plate (131), for example, the upper side of the case (120), and may be exposed to the outside. This third terminal plate (133) may be seated and coupled to the terminal groove (122b). The second terminal plate (132) may be supported on one side of the first terminal plate (131), for example, on the inner surface of the case (120).

[0090] The terminal groove (122b) may be interposed between the second terminal plate (132) and the third terminal plate (133). The second terminal plate (132) may be interposed under the terminal groove (122b). Accordingly, the second terminal plate (132) and the first current collector plate (160) may come into contact, thereby forming an electrical and mechanical connection between the terminal (130) and the first current collector plate (160). Accordingly, when the first electrode plate (111) of the electrode assembly (110) is a positive electrode, the terminal (130) may function as a positive terminal. The terminal (130) and the case (120) may have different polarities.

[0091] In some examples, the first terminal plate (131) and the second terminal plate (132), and the first terminal plate (131) and the third terminal plate (133) may be joined by welding, respectively. That is, the first terminal plate (131) and the second terminal plate (132) may be welded inside the case (120). In addition, the first terminal plate (131) and the third terminal plate (133) may be welded outside the case (120). That is, the contact points of the first terminal plate (131), the second terminal plate (132), and the third terminal plate (133) may be formed by welding. In some examples, the welding may be possible by ultrasonic, laser, or resistance.

[0092] Accordingly, the terminal (130) of one embodiment can form a slim separation terminal by connecting multiple terminal plates by welding rather than separating the terminals by mechanical force. For example, the thickness (T1) from the lower surface of the second terminal plate (132) to the upper surface of the crimping portion (122c) can be 2 mm or less.

[0093] In some examples, an insulating member (140) may be interposed for sealing and electrical insulation between the terminal (130) and the case (120). More specifically, the insulating member (140) may include a first insulating member (141) interposed between a first terminal plate (131) and a through hole (122a) of the case (120), and a second insulating member (142) interposed between a second terminal plate (132) and an inner surface of the case (120). In addition, the insulating member (140) may include a third insulating member (143) interposed between a third terminal plate (133) and an outer surface of the case (120).

[0094] In one embodiment, after the first insulating member (141), the second insulating member (142), and the third insulating member (143) are joined to the upper surface (122) of the case (120), the first terminal plate (131) can be joined. Then, after the second terminal plate (132) and the third terminal plate (133) are interposed, the first terminal plate (131), the second terminal plate (132), and the third terminal plate (133) can be welded.

[0095] The insulating member (140) may be formed of a resin material such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), perfluoroalkoxy (PFA), etc. In some examples, the first insulating member (141) may use a PFA material having high heat resistance, and the second insulating member (142) and the third insulating member (143) may use PP. However, the present invention is not limited thereto, and the first insulating member (141) may be formed of a material having the same or higher heat resistance as the second insulating member (142) and the third insulating member (143).

[0096] The first insulating member (141) may be formed in a ring shape with a circular hole formed in the center. In addition, the first insulating member (141) may be formed with the same thickness as the thickness of the first terminal plate (131) (length based on the vertical direction in FIG. 1). The first insulating member (141) may be interposed in the through hole (122a) in a form that surrounds the perimeter of the first terminal plate (131). That is, the outer diameter (length based on the horizontal direction in FIG. 1) of the first insulating member (141) may be the same as the diameter of the through hole (122a).

[0097] The second insulating member (142) may be formed in a ring shape with a circular hole formed in the center. The inner diameter of the second insulating member (142) may be equal to the sum of the diameter of the first terminal plate (131) and the outer diameter of the first insulating member (141). In addition, the outer diameter of the second insulating member (142) may be equal to or greater than the diameter of the second terminal plate (132) so that the second terminal plate (132) does not come into contact with the case (120).

[0098] The third insulating member (143) may be formed in a ring shape with a circular hole formed in the center. The inner diameter of the third insulating member (143) may be equal to the sum of the diameter of the first terminal plate (131) and the outer diameter of the first insulating member (141). In addition, the outer diameter of the third insulating member (143) may be equal to the diameter of the third terminal plate (133), but is not limited thereto.

[0099] In some examples, the crimping portion (122c) may be formed to surround at least a portion of the third terminal plate (133) and the third insulating member (143) after the third terminal plate (133) and the third insulating member (143) are seated in the terminal groove (122b). For example, the crimping portion (122c) may be formed to surround the upper surface edge and the side surface of the third terminal plate (133). That is, the crimping portion (122c) may be formed at the connection portion between the end of the terminal groove (122b) and the upper surface side of the upper surface (122) of the case (120), thereby holding the third terminal plate (133) and the third insulating member (143) seated in the terminal groove (122b).

[0100] At this time, the secondary battery (100) may further include a gasket (150) interposed to seal and / or electrically insulate between the crimping portion (122c) and the third terminal plate (133) and the third insulating member (143). The gasket (150) may be formed in a shape that wraps around the upper edge and side of the third terminal plate (133) and the side of the third insulating member (143). The gasket (150) may be formed in a ring shape with a circular hole formed in the center. The gasket (150) may protrude toward the center more than the end of the crimping portion (122c). Accordingly, the third terminal plate (133) and the crimping portion (122c) may not come into contact. The gasket (150) may be formed of a resin material such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), or the like.

[0101] As described above, stress is generated on the third terminal plate (133) side and the gasket (150) by the crimping portion (122c), so that the terminal (130) can be fixed. For example, the phenomenon of the second terminal plate (132) and the third terminal plate (133) rotating or lifting after welding of the terminal (130) can be prevented by the crimping portion (122c).

[0102] Meanwhile, the first terminal plate (131) may be formed in a cylindrical shape as a pin connecting the second terminal plate (132) and the third terminal plate (133). The second terminal plate (132) and the third terminal plate (133) may be formed in a circular shape that is coupled to both sides of the first terminal plate (131). Accordingly, the through hole (122a) may also be formed in a circular shape. However, the shapes of the first terminal plate (131), the second terminal plate (132), and the third terminal plate (133) are not limited thereto, and may be formed in various shapes such as a square shape. If the shape of the first terminal plate (131) changes, the shape of the through hole (122a) may also change correspondingly. However, since the first insulating member (141) is interposed between the first terminal plate (131) and the through hole (122a), when the shape of the first terminal plate (131) and the outer surface shape of the first insulating member (141) are different, the shape of the through hole (122a) may change in response to the outer surface shape of the first insulating member (141).

[0103] The second terminal plate (132) may be formed in a circular shape. However, it is not limited thereto and may be formed in various shapes, such as an angular plate shape.

[0104] The second insulating member (142) may be formed so that the inner surface corresponds to the shape of the first terminal plate (131), and the outer surface corresponds to the shape of the second terminal plate (132). However, the present invention is not limited thereto, and the outer surface of the second insulating member (142) may be formed in various shapes with an outer diameter that is equal to or larger than that of the second terminal plate (132) so that the second terminal plate (132) does not come into contact with the case (120).

[0105] The third terminal plate (133) may be formed in a circular shape. However, it is not limited thereto and may be formed in various shapes, such as an angular plate shape.

[0106] The inner surface of the third insulating member (143) may be formed to correspond to the shape of the first terminal plate (131), and the outer surface may be formed to correspond to the shape of the third terminal plate (133). However, the present invention is not limited thereto, and when the outer surface of the third insulating member (143) and the shape of the third terminal plate (133) are different, the gasket (150) may be formed to correspond to the inner surface thereof.

[0107] Since the gasket (150) and the crimping portion (122c) are formed in a shape that wraps around the edge of the third terminal plate (133), they can be formed to correspond to the planar shape of the third terminal plate (133). For example, if the third terminal plate (133) is formed in a circular shape on a planar surface, the gasket (150) and the crimping portion (122c) can be formed along the circumference of the circle.

[0108] In some examples, the thickness of each of the second terminal plate (132) and the third terminal plate (133) may be thinner or equal to the thickness of each of the second insulating member (142) and the third insulating member (143). That is, as the thickness of the terminal plates decreases, the length of the step decreases, which may be useful for slimming.

[0109] FIG. 3 is an enlarged view of the upper side of a secondary battery according to another embodiment of the present invention. Referring to FIG. 3, it can be confirmed that the width (W2) of the first terminal plate (1131) is reduced compared to the width (W1) of the first terminal plate (131) of FIG. 2. In one embodiment, when the width of the first terminal plate (131, 1131) is small, the gap becomes smaller, which may be effective in terms of leakage. Here, when the first terminal plate (131, 1131) has a cylindrical structure, the width (W1, W2) may refer to the diameter of the first terminal plate (131, 1131). In some examples, as the width (W2) of the first terminal plate (1131) decreases, the through holes in the central areas of the second terminal plate (1132) and the third terminal plate (1133) may decrease, and the through hole (1122a) of the case may also decrease.

[0110] FIG. 4 is a cross-sectional view of the upper side of a secondary battery according to various embodiments of the present invention, FIG. 5 is an enlarged view of portion B of FIG. 4, and FIG. 6 is an enlarged view of portion B of FIG. 4 after fusion. In addition, FIGS. 7a to 7c are cross-sectional views for explaining the bonding process of FIG. 4.

[0111] Referring to FIGS. 3 to 7, the secondary battery (200) may include an electrode assembly (210), a cylindrical case (220) that accommodates the electrode assembly (210) and an electrolyte therein, a terminal (230) installed in a through hole (222a) provided at one end of the case (220), and an insulating member (240) interposed between the terminal (230) and the case (220). In addition, the secondary battery (200) may include a cap plate (not shown) that seals an opening at the other end of the case (220). In addition, the first electrode plate (211) may be electrically connected to the terminal (230) through the first current collector plate (260). The first current collector plate (260) and the first electrode plate (211) may be electrically and mechanically coupled to each other by welding. These components are described identically to the secondary battery (100) above, so their description is omitted. Below, the terminal (230) and insulating member (240) that are different will be described.

[0112] Referring to FIG. 5, the upper surface (222) of the case (220) may include a through hole (222a) formed in the central region. In some examples, the terminal (230) may be formed of a plurality of separable plates including a first terminal plate (231), a second terminal plate (232), and a third terminal plate (233). At this time, the first terminal plate (231) may be coupled to the through hole (222a), and the second terminal plate (232) and the third terminal plate (233) may be coupled to one side and the other side of the first terminal plate (231), respectively.

[0113] The third terminal plate (233) may be coupled to the other side of the first terminal plate (231), for example, the upper side of the case (220), and may be exposed to the outside. The second terminal plate (232) may be supported on one side of the first terminal plate (231), for example, on the inner surface of the case (220). Accordingly, the second terminal plate (232) and the first current collector plate (260) may come into contact, so that an electrical and mechanical connection between the terminal (230) and the first current collector plate (260) may be formed. Accordingly, when the first electrode plate (211) of the electrode assembly (210) is a positive electrode, the terminal (230) may function as a positive terminal. The terminal (230) and the case (220) may have different polarities.

[0114] In some examples, the first terminal plate (231) and the second terminal plate (232), and the first terminal plate (231) and the third terminal plate (233) may be joined by welding, respectively. That is, the first terminal plate (231) and the second terminal plate (232) may be welded inside the case (220). In addition, the first terminal plate (231) and the third terminal plate (233) may be welded outside the case (220). That is, the contact points of the first terminal plate (231), the second terminal plate (232), and the third terminal plate (233) may be formed by welding. In some examples, the welding may be possible by ultrasonic, laser, or resistance.

[0115] Accordingly, as described above, the terminal (230) of one embodiment can form a slim separation terminal by connecting multiple terminal plates by welding rather than separating the terminals by mechanical force. For example, the thickness (T2) from the lower surface of the second terminal plate (232) to the upper surface of the third terminal plate (233) can be 2 mm or less.

[0116] In some examples, an insulating member (240) may be interposed for sealing and electrical insulation between the terminal (230) and the case (220). More specifically, the insulating member (240) may include a first insulating member (241) interposed between the first terminal plate (231) and the through hole (222a) of the case (220), and a second insulating member (242) interposed between the second terminal plate (232) and the lower surface of the case (220). In addition, the insulating member (240) may include a third insulating member (243) interposed between the third terminal plate (233) and the upper surface of the case (220).

[0117] The insulating member (240) may be formed of a resin material such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), perfluoroalkoxy (PFA), etc.

[0118] The first insulating member (241) may be formed in a ring shape with a circular hole formed in the center. In addition, the first insulating member (241) may be formed with the same thickness as the thickness of the first terminal plate (231) (length based on the vertical direction in FIG. 3). The first insulating member (241) may be interposed in the through hole (222a) in a form that surrounds the perimeter of the first terminal plate (231). That is, the outer diameter (length based on the horizontal direction in FIG. 3) of the first insulating member (241) may be the same as the diameter of the through hole (222a).

[0119] The second insulating member (242) may be formed in a ring shape with a circular hole formed in the center. The inner diameter of the second insulating member (242) may be equal to the sum of the diameter of the first terminal plate (231) and the outer diameter of the first insulating member (241). In addition, the outer diameter of the second insulating member (242) may be larger than the diameter of the second terminal plate (232) so that the second terminal plate (232) is included in the second insulating member (242) during fusion. For example, the difference (D2 / 2) between the outer diameter of the second insulating member (242) and the diameter of the second terminal plate (232) may be 0.2 mm (see FIG. 5).

[0120] The second insulating member (242) may be formed of a heat-melting material and may be combined with the second terminal plate (232) by a heat-melting method. In this case, referring to FIG. 5, the thickness (T3) from the lower surface of the second terminal plate (132) to the upper surface of the second insulating member (142) after melding may be shorter than the thickness (T2) before melding. For example, before melding, the length of the portion where the second terminal plate (232) contacts the second insulating member (242) may be 0 mm (see FIG. 4), and after melding, the length (D1) of the portion where the second terminal plate (232) contacts the second insulating member (242) may be -1 mm (see FIG. 5).

[0121] The third insulating member (243) may be formed in a ring shape with a circular hole formed in the center. The inner diameter of the third insulating member (243) may be equal to the sum of the diameter of the first terminal plate (231) and the outer diameter of the first insulating member (241). In addition, the outer diameter of the third insulating member (243) may be larger than the diameter of the third terminal plate (233) so that the third terminal plate (233) is included in the third insulating member (243) during fusion. In addition, the third insulating member (243) may be interposed between the third terminal plate (233) and the outer surface of the upper surface (122) of the case (120) and may be exposed to the outside. As described above, the third insulating member (243) may be formed of a heat-fusion material and may be combined with the third terminal plate (233) by a heat-fusion method.

[0122] In some examples, the secondary battery (200) may not include a gasket (150), unlike the secondary battery (100), and thus leakage problems may occur. Accordingly, in one embodiment, the sealing may be maintained by welding after compression. That is, the sealing may be maintained by compression on an insulating member having good adhesion and sealing properties. For example, the first insulating member (241) may use a PFA material having high heat resistance, and the second insulating member (242) and the third insulating member (243) may use PP. However, the present invention is not limited thereto, and the first insulating member (241) may be formed of a material having the same or higher heat resistance as or than the second insulating member (242) and the third insulating member (243).

[0123] Meanwhile, in one embodiment, referring to FIGS. 7A to 7C, after the first insulating member (241), the second insulating member (242), and the third insulating member (243) are coupled to the upper surface (222) of the case (220), the first terminal plate (231) may be coupled. Then, after the second terminal plate (232) and the third terminal plate (233) are interposed, the first terminal plate (231), the second terminal plate (232), and the third terminal plate (233) may be welded. The secondary battery (100) according to the above-described embodiment may be used to manufacture a secondary battery pack (30). FIGS. 8A and 8B are drawings schematically showing the configuration of a secondary battery pack (30) according to an embodiment of the present invention.

[0124] Referring to FIGS. 8A and 8B, the secondary battery pack (30) may include a plurality of secondary battery modules (20) and a housing (31) for accommodating the plurality of secondary battery modules (20). For example, the housing (31) may include first and second housings (31-1, 31-2) that are coupled in a direction facing each other with the plurality of secondary battery modules (20) interposed therebetween. The plurality of secondary battery modules (20) may be electrically connected to each other using a bus bar (25), and the plurality of secondary battery modules (20) may be electrically connected to each other in a series / parallel or series-parallel mixed manner to obtain a required electrical output. In the drawing, for the convenience of illustration, components such as a bus bar, a cooling unit, and an external terminal for electrically connecting the secondary batteries (batteries) are omitted.

[0125] The secondary battery pack (30) can be mounted on a vehicle (50). The vehicle (50) may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle includes a four-wheeled vehicle or a two-wheeled vehicle.

[0126] Fig. 9a is a perspective view illustrating an exemplary vehicle body (40). Fig. 9b is a drawing for explaining a vehicle (50) including the secondary battery pack (30) of Fig. 8. In Fig. 9a, the secondary battery pack (30) may include a secondary battery pack cover (31-1) (which may correspond to the first housing) which is a part of a vehicle underbody (41) and a pack frame (31-2) (which may correspond to the second housing) which is disposed at the lower part of the vehicle underbody (41). The secondary battery pack cover (31-1) and the pack frame (31-2) may be formed integrally with the vehicle floor (42). The vehicle underbody (41) separates the inside and the outside of the vehicle, and the pack frame (12) may be disposed at the outside of the vehicle.

[0127] Referring to FIG. 9B, the vehicle (50) may be formed by combining additional components such as a hood (51) at the front of the vehicle and fenders (52) positioned at the front and rear of the vehicle, respectively, with the vehicle body (40). The vehicle (50) includes a secondary battery pack (30) including a secondary battery pack cover (31-1) and a pack frame (31-2), and the secondary battery pack (30) may be combined with the vehicle body (40). That is, the vehicle operates by receiving power from the secondary battery pack (30) according to one embodiment of the present invention.

[0128] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

Claims

1. An electrode assembly having a first electrode plate, a separator, and a second electrode plate; a cylindrical case in which the electrode assembly is accommodated; and Includes a terminal coupled to the through hole on the upper surface of the case, The terminal includes a first terminal plate coupled to the through hole of the case, and a second terminal plate and a third terminal plate coupled to one side and the other side of the first terminal plate, respectively. A secondary battery in which the first terminal plate and the second terminal plate, and the first terminal plate and the third terminal plate are each joined by welding.

2. In paragraph 1, A secondary battery in which the first terminal plate and the second terminal plate are welded inside the case.

3. In paragraph 1, A secondary battery in which the first terminal plate and the third terminal plate are welded on the outside of the case.

4. In paragraph 1, A secondary battery further comprising a first insulating member interposed between the first terminal plate and the through hole of the case.

5. In paragraph 4, A secondary battery further comprising a second insulating member interposed between the second terminal plate and the inner surface of the case.

6. In paragraph 5, A secondary battery further comprising a third insulating member interposed between the third terminal plate and the outer surface of the case.

7. In paragraph 6, A secondary battery in which the first insulating member is formed of a material having the same or higher heat resistance as the second insulating member and the third insulating member.

8. In paragraph 6, The above case includes a terminal groove formed in the central area of ​​the upper surface of the case centered around the through hole, The third terminal plate and the third insulating member are a secondary battery mounted in the terminal groove.

9. In paragraph 8, The above case includes a crimping portion formed along the end of the terminal groove, A secondary battery in which the crimping portion is formed in a shape that wraps around the edge of the third terminal plate.

10. In paragraph 9, A secondary battery further comprising a gasket interposed between the crimping portion and the third terminal plate.

11. In paragraph 10, A secondary battery in which the above gasket is formed in a form that wraps around the side and upper edges of the third terminal plate.

12. In paragraph 10, A secondary battery in which a circular hole is formed in the center of each of the gasket, the first insulating member, the second insulating member, and the third insulating member.

13. In paragraph 10, The above gasket is a secondary battery that protrudes toward the center from the end of the crimping portion.

14. In paragraph 10, A secondary battery wherein the diameter of the second terminal plate is equal to or smaller than the outer diameter of the second insulating member.

15. In paragraph 10, A secondary battery in which the diameter of the third terminal plate is the same as the outer diameter of the third insulating member.

16. In paragraph 6, A secondary battery wherein the diameters of the second terminal plate and the third terminal plate are smaller than the outer diameters of the second insulating member and the third insulating member.

17. In paragraph 16, A secondary battery wherein at least one of the second insulating member and the third insulating member is formed of a heat-sealing material.

18. In paragraph 16, A secondary battery in which at least one pair of the second terminal plate and the second insulating member, and the third terminal plate and the third insulating member are joined by a heat-fusion method.

19. In paragraph 16, A secondary battery in which a circular hole is formed in the center of each of the first insulating member, the second insulating member, and the third insulating member.

20. In paragraph 6, A secondary battery wherein the thickness of each of the second terminal plate and the third terminal plate is thinner or equal to the thickness of each of the second insulating member and the third insulating member.

Images