Cylindrical secondary battery

Abstract

The present invention relates to a cylindrical secondary battery capable of preventing damage and / or leakage and facilitating sealing by adjusting a compression rate at which a compression portion of a lower terminal presses a compression insulation member. According to one embodiment, disclosed is a cylindrical secondary battery comprising: an electrode assembly including a first electrode plate, a separator, and a second electrode plate; a case accommodating the electrode assembly, having an open lower end, and electrically connected to the second electrode plate; a first current collector plate interposed between the upper surface of the electrode assembly and the case and electrically connected to the first electrode plate; a terminal penetrating the upper surface of the case and having a lower end electrically and mechanically coupled to the upper surface of the first current collector plate; and a cap plate sealing the lower end of the case, wherein the terminal includes a head positioned on the upper side of the upper surface of the case, a fastening portion penetrating the case, and a compression portion positioned on the lower side of the case, and the compression portion is formed of two layers that are overlapped and pressed together around a bend portion.

Description

cylindrical secondary battery

[0001] Various embodiments of the present invention relate to cylindrical secondary batteries.

[0002] Typically, a cylindrical secondary battery includes a cylindrical electrode assembly, a cylindrical case that accommodates the electrode assembly and an electrolyte, and a cap assembly that is coupled to an opening on one side of the case to seal the case and electrically connect to the electrode assembly, thereby serving as a means for electrically connecting between an external component and the electrode assembly.

[0003] In the case of a battery module that uses multiple cylindrical secondary batteries, bus bars must be connected to the upper and lower parts of the secondary batteries, which causes the structure to become complex and the process time to become longer.

[0004] To address these issues, the can is provided with terminal holes on one open side and the opposite side, and the positive rivet terminals within the terminal holes are connected in a structure that is insulated from the can. This structure allows the busbars to be positioned on the same side of the secondary battery, facilitating easy busbar connection in the secondary battery module.

[0005] However, the positive rivet terminal and the can are connected by riveting the rivet terminal, but it is not easy to control the degree of compression of the rivet terminal, so cracks may occur due to excessive riveting or the sealing force may decrease due to insufficient compression.

[0006]

[0007]

[0008] 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.

[0009] The present invention provides a cylindrical secondary battery that is easy to seal and prevents damage and / or leakage by controlling the compression rate at which a compression portion of a lower terminal presses a compression insulating member.

[0010] In addition, the present invention provides a cylindrical secondary battery capable of preventing welding impurities from occurring inside the case or the electrode assembly from being damaged by welding heat, by welding between the terminal and the collector plate from the outside of the case through a terminal groove provided in the lower terminal.

[0011] In addition, the present invention fills the terminal groove provided in the lower terminal with the upper terminal, so that the upper surface of the terminal has a substantially flat upper surface, thereby preventing welding defects due to misalignment that may occur due to the terminal groove when welding a plurality of secondary batteries through a bus bar, or increased resistance due to insufficient welding area.

[0012] A cylindrical secondary battery according to an embodiment of the present invention comprises: an electrode assembly having a first electrode plate, a separator, and a second electrode plate; a case in which the electrode assembly is accommodated, the case having an open lower portion and electrically connected to the second electrode plate; a first current collector plate interposed between an upper surface of the electrode assembly and the case and electrically connected to the first electrode plate; a terminal penetrating the upper surface of the case and having a lower portion electrically and mechanically coupled to the upper surface of the first current collector plate; and a cap plate sealing the lower portion of the case, wherein the terminal comprises a head positioned on an upper side of the upper surface of the case, a fastening portion penetrating the case, and a compression portion positioned on a lower side of the case, wherein the compression portion can be compressed by overlapping two layers centered on a bending portion.

[0013] The above compression member may have a plurality of folds extending from the center where the fastening member is located to the bending member.

[0014] The above-mentioned compression member is provided with wrinkles by bending with a uniform thickness, and the interval between the wrinkles can be constant.

[0015] The above compression member may have a pitch of 40 to 50 wrinkles.

[0016] The above compression member may have a width of the wrinkle between the high point and the low point of the wrinkle that is equal to the thickness of the above fastening member.

[0017] The molding part may further include a bottom plate having a flat plate shape and a side wall connected to the bottom of the bottom plate and extending upward from an edge of the bottom plate, and located at the lower side of the compression part.

[0018] The width of the wrinkle between the high point and the low point of the wrinkle of the above compression member may be less than 50% of the thickness of the side wall of the above molding member.

[0019] The inner surface of the above side wall may be provided with screw threads.

[0020] It may further include a compression insulating member interposed between the compression portion and the case.

[0021] The above-mentioned compression insulating member extends further outward than the compression portion in a plane, and the compression insulating member may have a thickness in an area located above the compression portion that is thinner than a thickness in an area located outside the compression portion due to compression.

[0022] The above-mentioned compression insulating member may be compressed by the compression portion to have a compression ratio of 30% to 50%.

[0023] The lower terminal may include a lower terminal having a terminal groove having a certain depth from the upper surface downward, the head positioned on the upper side of the case, the fastening portion penetrating the case, and the pressing portion positioned on the lower side of the case, and an upper terminal filling the terminal groove of the lower terminal.

[0024] The first collector plate may be welded from the outside of the lower terminal through the terminal groove in a state where the upper surface thereof is in contact with the lower surface of the lower terminal, so that a welding bead may be positioned within the terminal groove.

[0025] The upper terminal includes a flange having a substantially flat plate shape and a connecting portion extending downward from the center of the flange, and may include screw threads provided on the outer surface of the connecting portion.

[0026] The above-mentioned fastening portion has screw threads on the inner surface and can be screw-connected with the screw threads of the above-mentioned connecting portion of the upper terminal.

[0027] The flange of the upper terminal and the upper surface of the lower terminal may be positioned on the same plane.

[0028] The head of the lower terminal is provided with a ring-shaped stepped groove from the top to the bottom, and the flange of the upper terminal can be seated and inserted.

[0029] The above-mentioned connecting portion may be spaced apart from the lower surface of the terminal groove.

[0030] It may further include a first gasket interposed between the terminal and the case.

[0031] It further includes a second gasket interposed between the case and the cap plate, wherein the cap plate may be non-polar.

[0032] A cylindrical secondary battery according to various embodiments of the present invention can prevent damage due to excessive compression or leakage due to insufficient compression by controlling the compression rate at which the compression portion of the lower terminal presses the compression insulating member interposed between the case and the terminal, and can facilitate sealing between the case and the terminal.

[0033] Cylindrical secondary batteries according to various embodiments of the present invention can weld between a terminal and a current collector plate from the outside of the case through a terminal groove provided in the terminal, thereby preventing welding impurities from occurring inside the case or the electrode assembly from being damaged by welding heat.

[0034] In addition, in various embodiments of the present invention, the cylindrical secondary battery welds between the current collector and the terminal within the terminal groove of the terminal, so that the welding bead is positioned within the terminal groove, thereby preventing the terminal from protruding due to the welding bead being positioned above the terminal.

[0035] In addition, in various embodiments of the present invention, the cylindrical secondary battery has a terminal groove provided in the lower terminal filled with the upper terminal, so that the upper surface of the terminal has a substantially flat upper surface, and thus, when welding a plurality of secondary batteries through a bus bar, it is possible to prevent welding defects due to misalignment caused by the terminal groove or increased resistance due to insufficient welding area.

[0036] Figure 1 is a perspective view illustrating a cylindrical secondary battery according to the present invention.

[0037] Figure 2 is a cross-sectional view of the cylindrical secondary battery illustrated in Figure 1.

[0038] Figure 3 is an enlarged view of part 3 of Figure 2.

[0039] Figure 4 is an enlarged view showing the lower terminal before it is formed in Figure 3.

[0040] Fig. 5 is a cross-sectional view of the compression portion cut from the lower terminal of Fig. 4.

[0041] Fig. 6 is a cross-sectional view showing an example of a lower terminal being formed by a forming tool.

[0042] Fig. 7 is an enlarged cross-sectional view showing another example of the position of a compression insulating member in a cylindrical secondary battery according to the present invention.

[0043] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0044] 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.

[0045] 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.

[0046] 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" include plural forms unless the context clearly dictates otherwise. Furthermore, when used herein, the words "comprise" and / or "comprising" 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.

[0047] 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. Accordingly, a first element, component, region, layer, or portion described below may refer to a second element, component, region, layer, or portion without departing from the teachings of the present invention.

[0048] Spatial terms such as "beneath," "below," "lower," "above," and "upper" are used to facilitate understanding of one element or feature depicted in the drawings relative to another element or feature. These spatial terms are intended 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 a drawing is flipped, an element described as "beneath" or "below" becomes "above" or "above." Therefore, "beneath" is a concept encompassing "top" or "below."

[0049] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings so that a person having ordinary skill in the art to which the present invention pertains can easily carry out the present invention.

[0050] Here, parts with similar configurations and operations are designated by the same drawing reference numerals throughout the specification. Furthermore, when a part is said to be electrically coupled to another part, this includes not only direct connection but also connection with another element intervening between them.

[0051] FIG. 1 is a perspective view illustrating a cylindrical secondary battery (100) according to the present invention, and FIG. 2 is a cross-sectional view taken longitudinally of the cylindrical secondary battery (100) illustrated in FIG. 1. In addition, FIG. 3 is an enlarged cross-sectional view illustrating part 3 of FIG. 2. Hereinafter, the cylindrical secondary battery (100) will be described with reference to FIGS. 1 to 3.

[0052] As illustrated in FIGS. 1 and 2, a cylindrical secondary battery (100) according to the present invention may include a case (110), an electrode assembly (120) housed inside the case (110), a terminal (150) coupled to a terminal hole provided at one end of the case (110), and a cap plate (160) sealing an opening at the other end of the case (110).

[0053] The case (110) includes a circular upper surface (111) and a side surface (112) extending downward from the edge of the upper surface (111) by a certain length. The upper surface (111) and the side surface (112) of the case (110) may be formed as an integral body. In addition, a round-shaped folded portion may be further included between the upper surface (111) and the side surface (112).

[0054] The circular upper surface (111) may have a flat circular plate shape and may have a terminal hole (111a) penetrating the center. The upper surface (111) may be coupled by having a terminal (150) inserted into the terminal hole (111a). A first gasket (116) for sealing and electrical insulation may be further interposed between the terminal hole (111a) and the terminal (150). The first gasket (116) may block contact between the terminal (150) and the case (110), thereby electrically separating them. The first gasket (116) may seal the terminal hole (111a) of the upper surface (111) of the case (110). The first gasket (116) may be formed of a resin material such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), or the like. The first gasket (116) extends along the upper surface (111) of the case (110), and can be interposed between the area where the terminal (150) and the upper surface (111) overlap on a plane. Of course, the first gasket (116) is provided only in the area corresponding to the terminal hole (111a), and a separate upper insulating member can be interposed in the area where the terminal (150) and the upper surface (111) overlap on a plane. Hereinafter, for the convenience of explanation, the first gasket (116) will be described as extending between the terminal hole (111a) and the terminal (150), and between the terminal (150) and the upper side of the upper surface (111) of the case (110).

[0055] In addition, the case (110) may further include an inner insulating member (117) provided to cover the inner surface of the upper surface (111). Here, the inner insulating member (117) may be attached to the inner surface of the upper surface (111) by coating or adhesion. Here, the inner surface of the upper surface (111) is a surface facing the upper surface of the electrode assembly (120), and may be the lower surface of the upper surface (111). The inner insulating member (117) may prevent contact between the upper surface (111) of the case (110) and the first electrode plate (121) of the electrode assembly (120). As another example, the inner insulating member (117) may extend to the inner surface of the bent portion. The inner insulating member (117) may be provided to cover the upper surface (111) and the inner surface of the bent portion, or may be provided to cover only the inner surface of the upper surface (111).

[0056] The cylindrical secondary battery (100) has an open bottom of the case (110) during the manufacturing process. Therefore, the cylindrical secondary battery (100) can be inserted with an electrolyte through the open bottom of the case (110) during the manufacturing process. At this time, the electrolyte and the electrode assembly (120) can be inserted into the case (110) with the open bottom facing upward. After the electrolyte and the electrode assembly (120) are inserted into the case (110), a cap plate (160) can be coupled to the open bottom to seal the interior of the case (110). Here, the electrolyte serves to enable lithium ions to move between the positive electrode plate (121) and the negative electrode plate (122) constituting the electrode assembly (120). The electrolyte may be a non-aqueous organic electrolyte that is a mixture of a lithium salt and a high-purity organic solvent. In addition, the electrolyte may be a polymer using a polymer electrolyte or a solid electrolyte, and the type of electrolyte is not limited here.

[0057] The case (110) may be formed of steel, steel alloy, aluminum, aluminum alloy, or an equivalent thereof, but the material is not limited thereto. In addition, the case (110) may be provided with a crimping part (114) bent at the end of the side portion (112) to wrap the cap plate (160). A second gasket (118) may be further interposed between the crimping part (114) and the cap plate (160). The second gasket (118) may block contact between the cap plate (160) and the case (110), thereby electrically isolating them. The second gasket (118) may seal between the case (110) and the cap plate (160).

[0058] In some examples, the case (110) may further be provided with a beading part (113) that is recessed inwardly from the upper side of the cap plate (160). The lower part of the case (110) may have a beading part (113) that is recessed inwardly on the upper side centered on the cap plate (160) and a crimping part (114) that is bent to cover the lower side. After the electrode assembly (120) is inserted through the open lower part of the case (110), the beading part (113) is formed to prevent the electrode assembly (120) from being separated from the case (110).

[0059] The electrode assembly (120) includes a first electrode plate (121), a second electrode plate (122), and a separator (123). The first electrode plate (121) may be a positive electrode plate, and the second electrode plate (122) may be a negative electrode plate. Of course, the opposite is also possible. For convenience of explanation, the following description will describe a case where the first electrode plate (121) is a positive electrode plate, and the second electrode plate (122) is a negative electrode plate.

[0060] The first electrode plate (121) is a plate-shaped metal foil made of aluminum (Al) coated with a positive electrode active material made of a transition metal oxide on at least one surface. In addition, the first electrode plate (121) may have a positive electrode non-coated portion on the upper portion where the positive electrode active material is not coated. Such a positive electrode non-coated portion may protrude upward from the electrode assembly (120). That is, the positive electrode non-coated portion of the first electrode plate (121) may protrude further upward than the second electrode plate (122) and the separator (123).

[0061] The second electrode plate (122) is a plate-shaped metal foil made of copper (Cu) or nickel (Ni) coated with a negative electrode active material such as graphite or carbon on at least one surface. In addition, the second electrode plate (122) may have a negative electrode non-coated portion on the lower portion where the negative electrode active material is not coated. Such a negative electrode non-coated portion may protrude downward from the electrode assembly (120). That is, the negative electrode non-coated portion of the second electrode plate (122) may protrude further downward than the first electrode plate (121) and the separator (123).

[0062] The separator (123) may be polyethylene (PE) or polypropylene (PP), but is not limited thereto in the present invention. The separator can prevent electrical shorts between the first electrode plate (121) and the second electrode plate (122) and only allow the movement of lithium ions.

[0063] The electrode assembly (120) is wound from the winding end after the first electrode plate (121), the second electrode plate (122), and the separator (123) are laminated, and is wound in a roughly cylindrical shape. In addition, the electrode assembly (120) may have a positive electrode non-coated portion that is not coated with a positive active material protrude upward from the first electrode plate (121), and a negative electrode non-coated portion that is not coated with a negative active material protrude downward from the second electrode plate (122). In addition, the electrode assembly (120) may have an outermost positive electrode non-coated portion that does not protrude upward, and an outermost negative electrode non-coated portion that does not protrude downward. That is, the electrode assembly (120) may have a concave step difference at the outermost upper and lower portions compared to other regions. Such an electrode assembly (120) can prevent contact between the electrode assembly (120) and the case (110) even if an inner insulating member (117) is not formed in the bent portion of the case (110).

[0064] 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 the group consisting of cobalt, manganese, nickel, and combinations thereof may be used.

[0065] 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.

[0066] As an example, a compound represented by any one of the following chemical formulas may be used. LiaA1-bXbO2-cDc(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiaMn2-bXbO4-cDc(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiaNi1-b-cCobXcO2-αDα(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); LiaNi1-b-cMnbXcO2-αDα(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); LiaNibCocL1dGeO2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); LiaNiGbO2(0.90≤a≤1.8, 0.001≤b≤0.1); LiaCoGbO2(0.90≤a≤1.8, 0.001≤b≤0.1); LiaMn1-bGbO2 (0.90≤a≤1.8, 0.001≤b≤0.1); LiaMn2GbO4 (0.90≤a≤1.8, 0.001≤b≤0.1); LiaMn1-gGgPO4(0.90≤a≤1.8, 0≤g≤0.5); Li(3-f)Fe2(PO4)3(0≤f≤2); LiaFePO4(0.90≤a≤1.8).

[0067] In the 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; and L1 is Mn, Al, or a combination thereof.

[0068] 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.

[0069] 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.

[0070] Al may be used as the above current collector, but is not limited thereto.

[0071] 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.

[0072] 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.

[0073] 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 can be silicon, a silicon-carbon composite, SiOx (0 < x < 2), a Si-based alloy, or a combination thereof.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] An electrolyte for a lithium secondary battery contains a non-aqueous organic solvent and a lithium salt.

[0081] The above non-aqueous organic solvent acts as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0082] 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.

[0083] Additionally, when using a carbonate solvent, a mixture of cyclic carbonate and chain carbonate can be used.

[0084] 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.

[0085] 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.

[0086] The above organic material may include a polyvinylidene fluoride-based antibody or a (meth)acrylic polymer.

[0087] 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.

[0088] 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. The first collector plate (130) may be a circular metal plate having a shape corresponding to the upper surface of the electrode assembly (120). The planar size of the first collector plate (130) may be equal to or smaller than the size of the upper surface of the electrode assembly (120). The first collector plate (130) may be made of aluminum (Al). The first collector plate (130) may be fixed and electrically connected to the first electrode plate (121) exposed to the upper portion of the electrode assembly (120) by welding while the lower surface thereof is in contact with the upper surface of the electrode assembly (120). The first collector plate (130) may be fixed and electrically connected to the terminal (150) by welding while the upper surface thereof is in contact with the lower surface of the terminal (150). The first collector plate (130) serves as a passage for current flow between the first electrode plate (121) of the electrode assembly (120) and the terminal (150). The first collector plate (130) may be welded to the electrode assembly (120), then housed in the case (110), and then welded to the terminal (150). The thickness of the first collector plate (130) may be thinner than the lower thickness (151h) of the lower terminal (151) of the terminal (150) to improve weldability.

[0089] The second collector plate (140) may include a circular flat portion (141) corresponding to the lower surface of the electrode assembly (120), and an extension portion (142) extending downward from an edge of the flat portion (141). The upper surface of the flat portion (141) may be in contact with the lower surface of the electrode assembly (120). The upper surface of the flat portion (141) may be fixed and electrically connected to the second electrode plate (122) exposed to the lower surface of the electrode assembly (120) by welding while in contact with the lower surface of the electrode assembly (120).

[0090] The extension portion (142) may extend downward from the edge of the flat portion (141). For example, a plurality of extension portions (142) may be provided so as to be spaced apart from each other along the edge of the flat portion (141). The extension portions (142) may be provided so as to be symmetrical with respect to each other with respect to the flat portion (141), but the invention is not limited thereto. The extension portion (142) may be extended by being bent downward from the edge of the flat portion (141). In addition, the extension portion (142) may be in contact with the inner surface of the side surface (112) of the case (110). Here, the inner surface may be the inner surface of the case (110). The end of the extension portion (142) may be positioned between the side surface (112) of the case (110) and the second gasket (118). Such an extension part (142) can be in contact with and coupled to the beading part (113) when the case (110) is provided with a beading part (113). For example, the extension part (142) can be coupled by welding while in contact with the side part (112) of the case (110) or the inner surface of the beading part (113). The second current collector plate (140) serves as a current flow path between the second electrode plate (122) of the electrode assembly (120) and the case (110). That is, the case (110) can be a negative terminal. In some examples, the second current collector plate (140) can be provided with a hole penetrating between the upper and lower surfaces at the center of the flat part (141), and the electrolyte can be easily injected into the electrode assembly (120) through the hole.

[0091] The terminal (150) can be inserted into a terminal hole (111a) provided on the upper surface (111) of the case (110) and can be in contact with and electrically connected to the first collector plate (130). The terminal (150) can be electrically connected to the first electrode plate (121) of the electrode assembly (120) through the first collector plate (130). The terminal (150) may be a positive terminal. The terminal (150) and the case (110) may have different polarities. The terminal (150) may be made of the same or similar material as the first collector plate (130) and the first electrode plate (121) of the electrode assembly (120).

[0092] The terminal (150) may include a lower terminal (151) and an upper terminal (152). The lower terminal (151) may have a terminal groove (151x) provided downward from the center of the upper surface. In addition, the lower terminal (151) may include a head (1511), a fastening portion (1512), a pressing portion (1513), and a forming portion (1514) sequentially provided from the outside to the inside of the case (110).

[0093] First, the head (1511) is a flat plate of approximately circular shape exposed to the upper portion of the case (110), and may be provided with a hole penetrating through the center. Here, the hole may be a part of a terminal groove (151x). The head (1511) may have an approximately ring shape in plan view. The head (1511) may be located on the upper side of the upper surface (111). The head (1511) may have an area overlapping the upper surface (111) in plan view. An insulating member that blocks electrical contact may be interposed between the head (1511) and the upper surface (111).

[0094] For example, a first gasket (116) that blocks electrical contact may be interposed in an area where the head (1511) and the upper surface (111) overlap on a plane. In addition, the first gasket (116) may be interposed between the fastening portion (1512) and the terminal hole (111a) of the case (110). At this time, the end of the upper portion of the first gasket (116) may extend further outward than the head (1511). That is, the first gasket (116) may be interposed between the lower terminal (151) and the case (110), thereby electrically insulating the lower terminal (151) and the case (110). The first gasket (116) may be in contact with the upper surface of the upper surface (111) of the case (110). The lower end of the first gasket (116) can be in contact with the compression insulating member (119).

[0095] The head (1511) may be provided with a ring-shaped stepped groove (1511a) extending downward from the upper surface. Here, the head (1511) may have a central region that is thinner than other regions due to the stepped groove (1511a).

[0096] The fastening portion (1512) may extend inwardly from the center region of the head (1511) toward the case (110). The fastening portion (1512) may have a substantially cylindrical shape, and the upper end may be connected to the head (1511) and the lower end may be connected to the upper end of the compression portion (1513). Here, the head (1511) may extend outwardly from the upper end of the fastening portion (1512) toward the upper surface (111). The fastening portion (1512) may have a uniform thickness. In addition, a screw thread (1512x) may be provided on the inner surface of the fastening portion (1512). Here, the inner surface may be a surface located inside the cylindrical fastening portion (1512). The inner surface of the fastening portion (1512) may be a portion of the terminal groove (151x). The screw thread (1512x) of the fastening portion (1512) may be provided for screw connection with the upper terminal (152).

[0097] The compression member (1513) may be provided at the lower end of the fastening member (1512). The compression member (1513) may be located on the lower side of the upper surface (111) of the case (110). The compression member (1513) may be compressed to apply pressure to the lower side of the central region of the upper surface (111) of the case (110). Here, a compression insulating member (119) may be further interposed between the compression member (1513) and the central region of the upper surface (111) of the case (110). The compression insulating member (119) may be in contact with the inner insulation member (117). Here, the compression insulating member (119) may be in contact with an end of the inner insulation member (117). Here, the compression insulating member (119) and the inner insulation member (117) may be interposed between the compression portion (1513) and the upper surface (111) of the case (110) so as not to overlap on a plane. The compression insulating member (119) may have a thinner thickness in an area located above the compression portion (1513) than in other areas. The compression insulating member (119) may be pressed by the compression portion (1513) to change its thickness. The compression insulating member (119) may be made of a resin material such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), or the like.

[0098] Fig. 4 is an enlarged view showing the state before the crimping portion (1513) is formed in the lower terminal (151). In addition, Fig. 5 is a cross-sectional view taken horizontally along the crimping portion (1513) in Fig. 4. Hereinafter, with reference to Figs. 4 and 5, the structure and forming of the crimping portion (1513) of the lower terminal (151) before it is formed will be described.

[0099] The pressing portion (1513) may have a roughly corrugated pipe shape before being pressed. Such a pressing portion (1513) may have a plurality of corrugations extending along the first direction (x), which is the height direction of the electrode assembly (120). The pressing portion (1513) may have corrugations at equal intervals and may have a uniform thickness. The pitch, which is the number of corrugations of the pressing portion (1513), may be 40 to 50. Here, if the pitch of the corrugations of the pressing portion (1513) is less than 40, the strength of the pressing portion (1513) may increase due to an increase in the width of the pitch, making it difficult to press. In addition, if the pitch of the corrugations of the pressing portion (1513) exceeds 50, it may be difficult to manufacture, and the strength may increase due to an increase in the number of pitches. Here, the compression member (1513) may have a wrinkle width, which is the width between the high and low points of the wrinkle, that is equal to the thickness of the fastening member (1512).

[0100] The forming part (1514) may be connected to the lower side of the pressing part (1513) as a substantially flat plate. The forming part (1514) may have a groove formed in the center from the upper surface downward, and the groove may be a portion of the terminal groove (151x). That is, the terminal groove (151x) may be a groove that extends to a portion of the upper part of the forming part (1514) by penetrating the head (1511), the fastening part (1512), and the pressing part (1513). The forming part (1514) may have a substantially flat bottom plate (1514b) by the groove, and a side wall (1514a) that extends upward from an edge of the bottom plate (1514b) and has a cylindrical shape. The upper end of the side wall (1514b) of the forming part (1514) may be coupled to the lower side of the pressing part (1513). Here, the thickness of the side wall (1514b) of the molding portion (1514) may be greater than the width of the wrinkles of the pressing portion (1513) and the thickness of the fastening portion (1512). Preferably, the width of the wrinkles of the pressing portion (1513) may be smaller than 50% of the width of the wrinkles of the molding portion (1514). A screw thread (1514x) may be provided on the inner surface of the side wall (1514b) of the molding portion (1514). The inner surface of the molding portion (1514) may be a portion of the terminal groove (151x). The inner surface of the molding portion (1514) may be closer to the center of the lower terminal (151) than the inner surface of the fastening portion (1512) and the inner surface of the pressing portion (1513). In this way, the forming part (1514) can prevent the pressing part (1513) and the fastening part (1512) from being damaged by contact with the forming tool (A) during forming by combining the forming tool (A) with the screw thread (1514x).

[0101] The screw thread (1514x) of the forming part (1514) can be combined with a forming tool to press the pressing part (1513) of the lower terminal (151).

[0102] The lower terminal (151) can be formed by deforming and compressing the crimping portion (1513) by the rotation of the forming tool (A) after the forming tool (A) is coupled to the screw thread (1514) of the forming portion (1514), as illustrated in FIG. 6. The crimping portion (1513) can be formed by bending the center of the first direction (x) outward by the forming tool (A) to form a bending portion (1513a). Thereafter, the crimping portion (1513) can be formed by the forming tool (A) so that the bending portion (1513a) is positioned on the outer side in a plane, and the upper and lower ends are adjacent to each other. Thereafter, the crimping portion (1513) can be bent and compressed by the forming tool (A). This crimping portion (1513) can be pressed toward the upper surface (111) of the case (110). That is, the compression portion (1513) can be compressed by the compression insulating member (119) by the bending portion (1513a) being bent and the upper and lower portions being adjacent to each other, thereby undergoing compression deformation (compression molding). The lower terminal (151) can control the degree to which the compression portion (1513) presses the compression insulating member (119). The compression portion (1513) can press the compression insulating member (119) to seal the terminal hole (110a) of the case (110). The compression portion (1513) can be folded around the bending portion (1513a) to form two overlapping layers.

[0103] Referring to Table 1, there is test data for testing the sealing force according to the initial thickness of the compression insulating member (119) and the thickness and compression ratio by compression of the compression portion (1513). Here, the initial thickness of the compression insulating member (119) may be 5 mm.

[0104] Experimental example: Thickness after compression Compression ratio Sealing force 10.1mm 80% X 20.2mm 60% X 30.25mm 50% O 40.3mm 40% O 50.35mm 30% O 60.4mm 20% X 70.5mm 0% X

[0105] As shown in the results of Experimental Examples 3 to 5 in Table 1, when the thickness (compressibility) of the compression insulating member (119) is reduced to approximately 30% to 50% by the compression of the compression portion (1513), the sealing force can be easily achieved. In the case of Experimental Examples 1 and 2, when the compression capability of the compression insulating member (119) exceeds 50%, the compression insulating member (119) may be excessively compressed, causing a crack to occur, resulting in leakage. In addition, when the compression capability of the compression insulating member (119) is less than 30%, as in Experimental Examples 6 and 7, the sealing between the compression portion (1513) and the compression insulating member (119) may not be easy, resulting in leakage.

[0106] In this way, the compression insulating member (119) pressed by the compression unit (1513) has a reduced thickness compared to before being pressed, so that the thickness of the compression insulating member (119) located on the outer side on a plane may be thicker than the area pressed by the compression unit (1513). Here, the compression unit (1513) can pressurize the compression insulating member (119) at a desired compression ratio to seal the space between the lower terminal (151) and the case (110).

[0107] The compression portion (1513) may be formed so that the wrinkles extend parallel to the upper surface of the case (110). The compression portion (1513) may extend outwardly. The wrinkles of the compression portion (1513) may be bent and compressed to extend unevenly, and the bent center portion may extend outward as the wrinkles unfold. That is, the compression portion (1513) may be positioned further outward in plane compared to the upper and lower portions connected to the forming portion (1514) and the fastening portion (1512).

[0108] As another example, the compression insulating member (119) may be positioned on the lower side of the inner insulating member (117), as illustrated in FIG. 7. At this time, the upper surface of the compression insulating member (119) may be in contact with and adhere to the lower surface of the inner insulating member (117). That is, the compression insulating member (119) may be interposed between the case (110) and the compression portion (1513) of the lower terminal (151) so as to overlap the inner insulating member (117) on a plane.

[0109] The lower terminal (151) may have a head (1511) and a crimping portion (1513) having a larger diameter than other areas. The head (1511) and the crimping portion (1513) of the lower terminal (151) may overlap the case (110) on a plane. The lower terminal (151) may be pressed with the case (110) interposed between the head (1511) and the crimping portion (1513), so that the case (110) and the lower terminal (151) may be sealed. Of course, an insulating material may be interposed between the lower terminal (151) and the case (110), so as to insulate the lower terminal (151) and the case (110). Here, the insulating member is illustrated as a compression insulating member (119) and a first gasket (116), but the compression insulating member (119) may be formed integrally with the first gasket (116), and in this case, a separate insulating member may be provided between the head (1511) of the lower terminal (151) and the upper surface of the case (110).

[0110] The lower terminal (151) can be joined to the first collector plate (130) by welding through the terminal groove (151x) while the lower surface of the bottom plate (1514b) of the molded portion (1514) is in contact with the first collector plate (130). In addition, the lower terminal (151) is provided with a terminal groove (151x) so that welding with the first collector plate (130) is possible from the outside of the lower terminal (151), thereby preventing welding foreign substances from being generated inside the case (110) and preventing the electrode assembly (120) from being damaged by welding heat. The lower terminal (151) is provided with a terminal groove (151x), so that even when welding with the first collector plate (130) from the outside of the lower terminal (151), the welding bead can be positioned within the groove of the molded portion (1514) at the terminal groove (151x). Additionally, the terminal groove (151x) may have an upper inner diameter larger than a lower inner diameter.

[0111] The upper terminal (152) can be inserted into the terminal groove (151x) of the lower terminal (151) and coupled. The upper terminal (152) can include a flange (1521) having a substantially flat plate shape and a coupling portion (1522) extending downward from the center of the flange (1521).

[0112] The flange (1521) can be seated and inserted into the step groove (1511a) of the head (1511) of the lower terminal (151). The upper surface of the flange (1521) can be flush with the upper surface of the head (1511) of the lower terminal (151).

[0113] In addition, the connecting portion (1522) can be inserted into the terminal groove (151x) provided in the head (1511). Such connecting portion (1522) is provided with screw threads (1522x) on the outer surface and can be screw-connected with the screw threads (1512x) of the fastening portion (1512) of the lower terminal (151). The lower surface of such connecting portion (1522) can be spaced apart from the bottom plate (1514b) of the molding portion (1514).

[0114] The upper terminal (152) is coupled into the terminal groove (151x) of the lower terminal (151), so that the terminal (150) can have a flat upper surface.

[0115] The cap plate (160) is a circular metal plate and can be coupled to the lower portion of the case (110). The lower surface of the cap plate (160) can be exposed to the outside. The cap plate (160) can be coupled to the lower portion of the case (110) with a second gasket (118) interposed therebetween, thereby preventing electrical connection with the case (110). Since the cap plate (160) is not electrically connected to the positive or negative electrode of the electrode assembly (120), there may be no separate electrical polarity.

[0116] The cap plate (160) can be fixed at the edge region (162) by the crimping portion (114) of the case (110). More specifically, the cap plate (160) can be seated at the lower portion of the case (110) with the second gasket (118) interposed therebetween. Thereafter, the crimping portion (114) of the case (110) can be bent inwardly of the cap plate (160) to press the second gasket (118), thereby coupling the cap plate (160) and the case (110). The second gasket (118) can be formed of a resin material such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), or the like. This second gasket (118) can seal by applying pressure between the case (110) and the cap plate (160), and can prevent the cap plate (160) from being separated from the case (110). The upper portion of the second gasket (118) can be interposed between the case (110) and the cap plate (160). The lower portion of the second gasket (118) can protrude toward the center of the cap plate (160) compared to the crimping portion (114).

[0117] The cap plate (160) may include an outwardly protruding region, and the cap plate (160) is provided with a vent (161) so that the vent can be opened at a pressure set in the protruding region. The vent (161) may be thinner than other regions of the cap plate (160). The vent (161) may be a notch formed upward from the lower surface of the cap plate (160). Here, the protruding region may be provided in a roughly ring shape on a plane so as to be spaced apart from the center and the edge region where the second gasket (170) comes into contact with the cap plate (160).

[0118] The cylindrical secondary battery (100) can discharge the excessive internal pressure by rupturing the vent (161) when excessive internal pressure occurs inside the case (110). The vent (161) of the cap plate (160) can be formed to be spaced apart from the center and have a ring shape in a plane. As another example, the vent (161) can have at least one pattern having a straight or curved shape in a plane. The thickness of such a vent (161) can be thinner than the thickness of other areas of the cap plate (160).

[0119] Since the cylindrical secondary battery (100) can control the compression ratio at which the compression portion (1513) of the lower terminal (151) presses the compression insulating member (119), damage or leakage due to excessive compression or under-compression can be prevented and sealing can be facilitated.

[0120] The cylindrical secondary battery (100) can be welded between the terminal (150) and the first collector plate (130) from the outside of the case (110) through the terminal groove (151x) provided in the lower terminal (151). Therefore, the cylindrical secondary battery (100) can prevent welding impurities from occurring inside the case (110) or the electrode assembly (120) from being damaged by welding heat.

[0121] In addition, the cylindrical secondary battery (100) can be electrically connected to another adjacent cylindrical secondary battery (100) via a bus bar. The cylindrical secondary battery (100) can be contacted and coupled with the bus bar to a terminal (150) or a case (110). Since the cylindrical secondary battery (100) has a flat plate shape with an upper terminal (152) coupled to the upper side of a lower terminal (151) having a terminal groove (151x), welding with the bus bar can be easy.

[0122] The above description is only one embodiment for implementing the cylindrical secondary battery according to the present invention, and the present invention is not limited to the above-described embodiment, and as claimed in the following claims, it will be understood that the technical spirit of the present invention exists to the extent that various modifications can be implemented by anyone having ordinary skill in the art to which the present invention pertains without departing from the gist of the present invention.

Claims

1. An electrode assembly having a first electrode plate, a separator, and a second electrode plate; A case in which the electrode assembly is accommodated, the lower portion of which is open and electrically connected to the second electrode plate; A first collector plate interposed between the upper surface of the electrode assembly and the case and electrically connected to the first electrode plate; A terminal penetrating the upper surface of the case and having a lower surface electrically and mechanically connected to the upper surface of the first collector plate; and Includes a cap plate that seals the lower part of the case, The terminal includes a head positioned on the upper side of the upper surface of the case, a fastening portion penetrating the case, and a compression portion positioned on the lower side of the case. The above compression part is a cylindrical secondary battery in which two layers are overlapped and compressed around the bending part.

2. In paragraph 1, A cylindrical secondary battery having a plurality of wrinkles extending from the center where the fastening portion is located to the bending portion.

3. In paragraph 2, The above-mentioned compression member is a cylindrical secondary battery having wrinkles formed by bending with a uniform thickness and having a constant gap between the wrinkles.

4. In paragraph 2, The above-mentioned compression member is a cylindrical secondary battery having a pitch of 40 to 50 wrinkles.

5. In paragraph 2, The above-mentioned compression member is a cylindrical secondary battery in which the width of the wrinkle between the high point and the low point of the wrinkle is the same as the thickness of the above-mentioned fastening member.

6. In paragraph 2, Located on the lower side of the above compression part, A cylindrical secondary battery further comprising a molded portion having a bottom plate having a flat plate shape and a side wall joined to the lower side of the compression portion extending upward from an edge of the bottom plate.

7. In paragraph 6, The above-mentioned compression member is a cylindrical secondary battery in which the width of the wrinkle between the high point and the low point of the wrinkle is less than 50% of the thickness of the side wall of the above-mentioned molding member.

8. In paragraph 6, A cylindrical secondary battery having a screw thread on the inner surface of the side wall.

9. In paragraph 1, A cylindrical secondary battery further comprising a compression insulating member interposed between the compression portion and the case.

10. In paragraph 9, The above compression insulating member extends further outward than the compression portion on a plane, The above compression insulating member is a cylindrical secondary battery in which the thickness of the region located on the upper side of the compression portion is thinner than the thickness of the region located outside the compression portion.

11. In paragraph 10, A cylindrical secondary battery in which the above-mentioned compression insulating member is compressed by the compression portion to have a compression ratio of 30% to 50%.

12. In paragraph 1, The lower terminal has a terminal groove having a certain depth from the upper surface downward, and includes the head located on the upper side of the case, the fastening portion penetrating the case, and the pressing portion located on the lower side of the case. A cylindrical secondary battery comprising an upper terminal filling a terminal groove of the lower terminal.

13. In paragraph 12, A cylindrical secondary battery in which the first collector plate is welded from the outside of the lower terminal through the terminal groove in a state in which the upper surface is in contact with the lower surface of the lower terminal, and a welding bead is positioned within the terminal groove.

14. In paragraph 12, A cylindrical secondary battery having an upper terminal having a flange having a substantially flat plate shape and a connecting portion extending downward from the center of the flange, and a screw thread provided on the outer surface of the connecting portion.

15. In paragraph 14, A cylindrical secondary battery in which the above-mentioned fastening portion has screw threads on the inner surface and is screw-connected with the screw threads of the above-mentioned connecting portion of the upper terminal.

16. In paragraph 14, A cylindrical secondary battery in which the flange of the upper terminal and the upper surface of the lower terminal are located on the same plane.

17. In paragraph 14, A cylindrical secondary battery having a ring-shaped stepped groove from the top surface to the bottom of the head of the lower terminal, into which the flange of the upper terminal is seated and inserted.

18. In paragraph 14, The above-mentioned connecting portion is a cylindrical secondary battery having a lower surface spaced apart from the lower surface of the terminal groove.

19. In paragraph 1, A cylindrical secondary battery further comprising a first gasket interposed between the terminal and the case.

20. In paragraph 1, Further comprising a second gasket interposed between the case and the cap plate, The above cap plate is a non-polar cylindrical secondary battery.

Images