Secondary battery

Abstract

Disclosed herein is a secondary battery including a cover assembly that reduces the overall resistance of the secondary battery, improves space utilization, and enhances sealing performance by preventing exposure of a welded portion. The secondary battery includes a case, an electrode assembly, and a cover assembly. The case includes an opening. The electrode assembly is inserted into the case through the opening and includes an electrode portion and a foil tab formed on the electrode portion. The cover assembly seals the opening of the case into which the electrode assembly is inserted. The cover assembly includes a cover plate, an upper insulating plate, and an electrode terminal. The cover plate includes a through-hole. The upper insulating plate is formed on the cover plate and includes a ceramic layer and a filler metal layer formed on upper and lower surfaces of the ceramic layer. The electrode terminal is formed on the upper insulating plate.

Description

Cross-reference to related applications

[0001] This application claims priority to Korean Patent Application No. 10-2025-0044346, filed on April 4, 2025, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] This disclosure relates to secondary batteries. Background Technology

[0003] Secondary batteries, which are easy to apply to various product groups and have electrical characteristics such as high energy density, are widely used not only in portable devices, but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs) powered by electric power sources.

[0004] Because secondary batteries can significantly reduce the use of fossil fuels and do not produce any byproducts from energy use, they have attracted attention as a new energy source for improving eco-friendliness and energy efficiency.

[0005] Currently, the secondary batteries widely used in this field include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries. The operating voltage range of a single secondary battery cell is approximately 2.5 V to approximately 4.5 V.

[0006] Secondary batteries can be classified into can-type and pouch-type secondary batteries based on the shape of their battery casing. In can-type secondary batteries, the electrode assembly is housed in a metal can, while in pouch-type secondary batteries, the electrode assembly is housed in a pouch formed of aluminum laminates. Based on the shape of the metal can, can-type secondary batteries can be further classified into cylindrical and prismatic secondary batteries.

[0007] The prismatic secondary battery includes an electrode assembly housed in a metal casing and a cover assembly connected to the open end of the metal casing.

[0008] In the cover assembly according to the relevant technology, the riveting is used to connect the electrode terminals to the cover plate, and thus increases the number of parts, thereby increasing the total resistance of the secondary battery and reducing space utilization due to the riveting.

[0009] Furthermore, the welded parts are exposed to the outside, and the electrolyte or gas inside the box may leak out of the box through the exposed welded parts, and external moisture or air may penetrate into the box, thereby reducing the efficiency of the battery. Summary of the Invention

[0010] Therefore, the purpose of this disclosure is to provide a secondary battery including a cover assembly that can reduce the total resistance of the secondary battery, improve space utilization, and enhance sealing performance by preventing welded portions from being exposed to the outside.

[0011] A secondary battery according to embodiments of the present disclosure may include a housing, an electrode assembly, and a cover assembly. The housing may include an opening. The electrode assembly can be inserted into the housing through the opening and may include electrode portions and a plurality of foil tabs formed on the electrode portions. The cover assembly may seal the opening of the housing into which the electrode assembly is inserted. The cover assembly may include a cover plate, an upper insulating plate, and electrode terminals. The cover plate may include through holes. The upper insulating plate may be disposed on the cover plate and may include a ceramic layer and filler metal layers formed on the upper and lower surfaces of the ceramic layer. Electrode terminals may be formed on the upper insulating plate.

[0012] In the secondary battery according to embodiments of the present disclosure, the cover plate and electrode terminals can each be made of a metal having a first melting point. The filler metal layer can have a second melting point lower than the first melting point.

[0013] In the secondary battery according to embodiments of the present disclosure, the filling metal layer may be made of an aluminum-silicon based alloy or an aluminum-germanium based alloy.

[0014] In the secondary battery according to embodiments of the present disclosure, the filling metal layer may include titanium (Ti), copper (Cu) or magnesium (Mg) as an additive.

[0015] The secondary battery according to embodiments of the present disclosure may further include a current collector, which includes a current collector body and a current collector protrusion. The electrode terminal may include an insertion recess in its central portion, into which the current collector protrusion is inserted, and the insertion recess communicates with a through hole.

[0016] In the secondary battery according to the embodiments of the present disclosure, a fitting groove may be formed in the inner peripheral surface of the insertion recess, and a fitting portion fitting into the fitting groove may be formed in the outer peripheral surface of the current collecting protrusion.

[0017] In the secondary battery according to an embodiment of the present disclosure, the fitting slot can be formed into a tapered shape with its width decreasing upwards. The fitting portion can be formed into a shape corresponding to the fitting slot.

[0018] In the secondary battery according to an embodiment of the present disclosure, the cover assembly may further include a lower insulating plate formed below the cover plate, and includes an insertion protrusion at its central portion that inserts into a through hole. The insertion protrusion may be formed to extend upward along the inner wall of the through hole.

[0019] The secondary battery according to embodiments of this disclosure may further include a current collector, which includes a current collector body and a current collector protrusion. The current collector protrusion can be inserted into an insertion hole formed in the current collector protrusion and can be formed into a cylindrical shape having a cross-section with a diameter decreasing from a lower portion to an upper portion. The diameter of the lower portion of the current collector protrusion can be larger than the diameter of the insertion hole.

[0020] In a secondary battery according to an embodiment of the present disclosure, the electrode terminals and the current collector protrusion inserted into the insertion recess can be connected to each other by welding.

[0021] In the secondary battery according to embodiments of the present disclosure, the ceramic layer may include at least one through-hole. The filler metal layer may include at least one of aluminum-silicon based alloys, aluminum-zinc based alloys, flux-based non-conductive brazing materials, and glass-ceramic brazing materials.

[0022] In a secondary battery according to an embodiment of the present disclosure, a plurality of foil tabs may be formed along one direction of the electrode assembly.

[0023] In a secondary battery according to an embodiment of the present disclosure, a plurality of foil tabs may be formed in opposite directions of the electrode assembly.

[0024] In the secondary battery according to an embodiment of the present disclosure, after the electrode assembly and the current collector are connected to each other, a first insulator can be attached to the current collector. After the outer surface of the electrode assembly is wrapped with a second insulator, the electrode assembly can be inserted into the housing. The outer surface of the housing with the electrode assembly inserted can be wrapped with a third insulator. Attached Figure Description

[0025] Figure 1 This is a perspective view of a secondary battery according to an embodiment of the present disclosure.

[0026] Figure 2 This is a partial exploded perspective view of a secondary battery according to an embodiment of the present disclosure.

[0027] Figure 3 This is a perspective view of an electrode assembly in a secondary battery according to an embodiment of the present disclosure, wherein a plurality of first foil tabs and a plurality of second foil tabs are formed on the electrode portion.

[0028] Figure 4 This is a view illustrating the first electrode plate in a secondary battery according to an embodiment of the present disclosure.

[0029] Figure 5 This is a view illustrating the second electrode plate in a secondary battery according to an embodiment of the present disclosure.

[0030] Figure 6 and Figure 7This is a cross-sectional view of the cover assembly according to a first embodiment of the present disclosure.

[0031] Figure 8 This is a cross-sectional view of the cover assembly according to a second embodiment of the present disclosure.

[0032] Figure 9 This is a cross-sectional view of the cover assembly according to the third embodiment of the present disclosure.

[0033] Figure 10 This is a cross-sectional view of the cover assembly according to the fourth embodiment of the present disclosure.

[0034] Figure 11 This is a plan view of the ceramic layer of the cover assembly according to the fourth embodiment of the present disclosure.

[0035] Figure 12 It is along Figure 11 A cross-sectional view taken from line A-A'.

[0036] Figure 13 This is a view illustrating the process of connecting a current collector to a foil in a secondary battery according to an embodiment of the present disclosure.

[0037] Figure 14 This is a view illustrating the process of connecting the cover assembly to the current collector in a secondary battery according to an embodiment of the present disclosure.

[0038] Figure 15 This is a view illustrating the process of connecting a current collector to a foil in a secondary battery according to an embodiment of the present disclosure, where the foil is formed in opposite directions.

[0039] Figure 16 This is a view illustrating the process of connecting each cover assembly to its corresponding collector.

[0040] Figure 17 This is a view illustrating the process of attaching an insulator to an interconnected electrode assembly and current collector.

[0041] Figure 18 This is a schematic cross-sectional view of a portion of a conventional cylindrical secondary battery.

[0042] Figure 19 This is a schematic cross-sectional view of a portion of a cylindrical secondary battery with an insulating plate structure according to the present disclosure. Detailed Implementation

[0043] Because this disclosure can be modified in various forms and has various implementations, specific implementations will be illustrated in the accompanying drawings and described in detail with reference to the drawings. However, this is not intended to limit this disclosure to a particular mode of practice, and it should be understood that all variations, equivalents, and alternatives that do not depart from the spirit and scope of this disclosure are included in this disclosure.

[0044] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. In this disclosure, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. It will also be further understood that the terms “comprising,” “including,” “having,” etc., as used in this specification, are intended to specify the presence of the stated features, integers, steps, operations, elements, components, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof.

[0045] In the following, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that throughout the drawings, the same reference numerals refer to the same elements. To avoid unnecessarily obscuring the spirit of the disclosure, details of well-known configurations and functions may be omitted. For the same reason, some elements in the drawings are enlarged, omitted, or depicted schematically.

[0046] Figure 1 This is a perspective view of a secondary battery according to an embodiment of the present disclosure. Figure 2 This is a partial exploded perspective view of a secondary battery according to an embodiment of the present disclosure. Figure 3 This is a perspective view of an electrode assembly in a secondary battery according to an embodiment of the present disclosure, wherein a plurality of first foil tabs and a plurality of second foil tabs are formed on the electrode portion. Figure 4 This is a view illustrating the first electrode plate in a secondary battery according to an embodiment of the present disclosure. Figure 5 This is a view illustrating the second electrode plate in a secondary battery according to an embodiment of the present disclosure.

[0047] like Figure 1 and Figure 2 As illustrated, the secondary battery 1000 according to an embodiment of the present disclosure includes a housing 1100, an electrode assembly 1200, a current collector 1300, and a cover assembly 1400.

[0048] The housing 1100 forms the external shape of the secondary battery 1000. The housing 1100 may define a space capable of housing the electrode assembly 1200 therein, and may have an opening on one of its surfaces. In this embodiment, the housing 1100 has a cuboid shape, but is not limited thereto, and can be modified in various ways. The housing 1100 may be made of a rigid material capable of protecting the electrode assembly 1200 housed therein. For example, the housing 1100 may be made of metal, such as aluminum or stainless steel.

[0049] The electrolyte can be housed together with the electrode assembly 1200 in a cartridge 1100. The electrolyte may include lithium salts such as LiPF6 or LiBF4 in organic solvents such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), or dimethyl carbonate (DMC). The electrolyte may be a liquid, solid, or gel phase.

[0050] The electrode assembly 1200 is housed in the housing 1100. The electrode assembly 1200 can be inserted into the housing 1100 through an opening in the housing 1100. Figure 3 As illustrated, the electrode assembly 1200 includes an electrode portion 1210, a plurality of first foil tabs 1220, and a plurality of second foil tabs 1230. The plurality of first foil tabs 1220 and the plurality of second foil tabs 1230 are disposed on one end of the electrode portion 1210. In other embodiments, the plurality of first foil tabs 1220 may be disposed on one side surface of the electrode portion 1210, and the plurality of second foil tabs 1230 may be disposed on the other side surface of the electrode portion 1210. The first foil tabs 1220 are aligned with each other, and the second foil tabs 1230 are aligned with each other.

[0051] like Figures 3 to 5 As shown in the figure, the electrode portion 1210 includes a plurality of first electrode plates 1211, a plurality of second electrode plates 1212, and a separator.

[0052] Active materials can be applied to multiple first electrode plates 1211 and multiple second electrode plates 1212. The multiple first electrode plates 1211 can be formed by applying an active material, such as a transition metal oxide, to a metal plate, such as an aluminum plate. The multiple first electrode plates 1211 can be positive electrode plates. The multiple second electrode plates 1212 can be formed by applying an active material, such as graphite or carbon, to a metal plate, such as a copper plate or a nickel plate. The multiple second electrode plates 1212 can be negative electrode plates.

[0053] A separator is provided between the plurality of first electrode plates 1211 and the plurality of second electrode plates 1212 to prevent short circuits between the plurality of first electrode plates 1211 and the plurality of second electrode plates 1212. The separator may be made of polyethylene, polypropylene, or composite materials thereof.

[0054] Electrode portion 1210 can be formed by positioning a spacer between alternately arranged first electrode plate 1211 and second electrode plate 1212. In other words, in an embodiment, electrode portion 1210 can be formed by stacking the first electrode plate 1211, the spacer, the second electrode plate 1212 and the spacer in the listed order dozens to hundreds of times.

[0055] Although the electrode assembly 1200 is illustrated as including a single electrode portion 1210 in this embodiment, in other embodiments, the electrode assembly 1200 may include multiple electrode portions 1210. The multiple electrode portions 1210 may be electrically connected to each other.

[0056] Foil tabs 1220 and 1230 without active material are formed at corresponding ends of a plurality of first electrode plates 1211 and a plurality of second electrode plates 1212. In an embodiment, each of the first electrode plates 1211 and the second electrode plates 1212, and a corresponding one of the foil tabs 1220 and 1230, can be integrally formed by cutting a predetermined portion of a single metal plate using a laser or the like, thus retaining the electrode plate 1211 or 1212 and the foil tab 1220 or 1230. The plurality of foil tabs 1220 and 1230 can be formed in a direction toward the cover assembly 1400.

[0057] When multiple first electrode plates 1211 and multiple second electrode plates 1212 are stacked, multiple first foil tabs 1220 overlap each other at a first position, and multiple second foil tabs 1230 overlap each other at a second position. In other words, multiple first foil tabs 1220 with the same polarity are grouped at the first position, and multiple second foil tabs 1230 with the same polarity are grouped at the second position. The first and second positions are spaced apart from each other on the electrode plates. The groups of multiple first foil tabs 1220 and groups of multiple second foil tabs 1230 may be spaced apart from each other in the longitudinal direction of the electrode assembly 1200.

[0058] Multiple foil pieces 1220 and 1230 overlapping in corresponding positions can be connected to the corresponding current collectors by ultrasonic welding, laser welding, etc., to facilitate current flow.

[0059] The collector 1300 includes a collector body 1310 and a collector protrusion 1320.

[0060] Each of the multiple foil tabs 1220 and 1230 can be bent and welded to the corresponding collector body 1310. The collector protrusion 1320 can be formed on the central portion of the collector body 1310.

[0061] The current collector protrusion 1320 can protrude upward from the upper surface of the current collector body 1310 and can be connected to the corresponding electrode terminal 1420 to electrically connect the electrode assembly 1200 to the electrode terminal 1420.

[0062] The current collector 1300 can be made of the same material as the plurality of foil tabs 1220 and 1230, and can have a predetermined thickness, for example, ranging from 0.8 mm to 1.2 mm. The use of a current collector with a relatively large thickness improves insulation and prevents damage to the separator.

[0063] Insulating material can be installed below the current collector 1300. The insulating material can be an insulating board or an insulating film.

[0064] After the plurality of first foil tabs 1220 are welded together and the plurality of second foil tabs 1230 are welded together, the current collector 1300 can be respectively disposed on the first foil tabs 1220 and the second foil tabs 1230.

[0065] After the multiple first foil tabs 1220 and multiple second foil tabs 1230 are bent, the current collector 1300 can be soldered to the multiple first foil tabs 1220 and multiple second foil tabs 1230 respectively. Soldering can be performed using ultrasonic welding, laser welding, etc.

[0066] The cover assembly 1400 seals the opening of the housing 1100 that accommodates the electrode assembly 1200. In this disclosure, the cover assembly 1400 can be configured to reduce the total resistance of the secondary battery, improve space utilization, and enhance sealing performance by preventing welded portions from being exposed to the outside. (See reference...) Figures 6 to 13 Various embodiments of the cover assembly 1400 are described in detail.

[0067] Figure 6 and Figure 7 This is a cross-sectional view of the cover assembly according to a first embodiment of the present disclosure. Figure 6 The diagram shows a cross-sectional view of the cover assembly, in which the collector 1300 is omitted. Figure 7 This is a cross-sectional view of the cover assembly connected to the collector 1300.

[0068] like Figure 6 and Figure 7 As illustrated in the figure, the cover assembly 1400_1 according to the first embodiment of the present disclosure may include a cover plate 1410, an electrode terminal 1420, an upper insulating plate 1430 and a lower insulating plate 1440.

[0069] The cover 1410 may have a plate-like shape that covers the opening of the box 1100 and may include at least one through hole 1410a. The cover 1410 may have a shape corresponding to the shape of the opening of the box 1100. The cover 1410 may be formed of the same material as the box 1100 and may be fixed to the box 1100 by a method such as laser welding.

[0070] The cover plate 1410 may have a venting portion 1411 and an electrolyte injection port 1412. The venting portion 1411 opens when the internal pressure of the casing 1100 exceeds a reference value. In this embodiment, the venting portion 1411 is formed in the cover plate 1410; however, in other embodiments, the venting portion 1411 may be formed in the casing 1100. Electrolyte can be injected into the casing 1100 through the electrolyte injection port 1412.

[0071] Electrode terminals 1420 may be formed above cover plate 1410. Electrode terminals 1420 may be electrically connected to foil tabs 1220 via current collector 1300. Electrode terminals 1420 may have a plate shape in the form of a circle or a rectangle.

[0072] An insertion recess 1421 with a predetermined diameter may be formed in the central portion of the electrode terminal 1420. The insertion recess 1421 may be formed to be recessed upward from the lower surface of the electrode terminal 1420. The insertion recess 1421 may be formed to communicate with the through hole 1410a of the cover plate 1410. The upper surface 1421a of the insertion recess 1421 may be formed at a position higher than the upper insulating plate 1430. The current collecting protrusion 1320 may be inserted into the insertion recess 1421.

[0073] The upper insulating plate 1430 can be disposed between the electrode terminal 1420 and the cover plate 1410. The upper insulating plate 1430 can electrically insulate the electrode terminal 1420 from the cover plate 1410.

[0074] A first step portion 1430a may be formed at the outer end of the upper insulating plate 1430, and a second step portion 1420a corresponding to the first step portion 1430a may be formed at the outer end of the electrode terminal 1420. When the second step portion 1420a is assembled into the first step portion 1430a, the electrode terminal 1420 and the upper insulating plate 1430 can be easily connected to each other.

[0075] In this disclosure, since the electrode terminals 1420 and the cover plate 1410 are welded and connected to the upper and lower surfaces of the upper insulating plate 1430 by an active brazing method, a rivetless cover assembly can be constructed. In this disclosure, the cover plate 1410 and the electrode terminals 1420 are made of metal, such as aluminum, and active brazing is a high-temperature joining technique for joining metals such as aluminum as well as ceramics or other non-metallic materials.

[0076] More specifically, the upper insulating plate 1430 may include a ceramic layer 1431 disposed at an intermediate position in the height direction and a filler metal layer 1432 formed on the upper and lower surfaces of the ceramic layer 1431.

[0077] The ceramic layer 1431 can be used for electrical insulation, thermal management, and mechanical protection inside or outside the secondary battery, and can be made of polypropylene (PP), polyamide (PA), polycarbonate (PC), polyethylene (PE), polyimide (PI), etc., exhibiting excellent electrical insulation properties, high chemical resistance (electrolyte resistance), and heat resistance. Additionally, the ceramic layer 1431 can contain a thermosetting resin to maintain heat resistance even when a portion of the upper insulating plate 1430 is melted.

[0078] The filler metal layer 1432 may be made of an aluminum-based alloy with a melting point lower than that of aluminum (approximately 660ºC). When the melting point of aluminum is defined as the first melting point, the filler metal layer 1432 may have a second melting point lower than the first melting point.

[0079] For example, the filler metal layer 1432 may be an aluminum-silicon based alloy (Al-Si alloy) with a melting point in the range of about 577ºC to about 582ºC. Alternatively, the filler metal layer 1432 may be an aluminum-germanium based alloy (Al-Ge alloy) with excellent oxidation resistance.

[0080] The filler metal layer 1432 may contain titanium (Ti), which is an active element that forms chemical bonds with the surface of the ceramic layer 1431 to improve the bonding strength. Alternatively, the filler metal layer 1432 may contain zirconium (Zr), which is an active element that removes oxide layers or promotes interaction with the ceramic surface. As another alternative, the filler metal layer 1432 may contain hafnium (Hf), which is an active element that performs a similar function to titanium and zirconium.

[0081] The filler metal layer 1432 may also contain copper (Cu) as an additive to adjust the melting temperature and improve the bonding strength, or magnesium (Mg) to help remove the oxide layer and improve the bonding strength.

[0082] As a filler metal layer 1432 reflecting the above-mentioned active elements and additives, the filler metal layer 1432 can be made of, for example, Al-12Si-Ti, Al-10Ge-Ti, Al-5Si-2Zr or Al-6Cu-1Ti.

[0083] In the manufacturing process of a secondary battery, an upper insulating plate 1430, formed by stacking a filler metal layer 1432 and a ceramic layer 1431, can be disposed on a cover plate 1410, and electrode terminals 1420 can be disposed on the upper insulating plate 1430. Subsequently, when heat is applied at a temperature between a first melting point and a second melting point, the filler metal layer 1432 can be melted. The molten lower filler metal layer 1432 can diffuse into the cover plate 1410 and the ceramic layer 1431, thereby bonding and sealing them. The molten upper filler metal layer 1432 can diffuse into the electrode terminals 1420 and the ceramic layer 1431, thereby bonding and sealing them. In this way, the electrode terminals 1420, the upper filler metal layer 1432, the ceramic layer 1431, the lower filler metal layer 1432, and the cover plate 1410 can be securely connected to each other.

[0084] A lower insulating plate 1440 is disposed below the cover plate 1410. The lower insulating plate 1440 has an insertion protrusion 1441 that inserts into a through hole 1410a and has an insertion hole 1442 formed therein. With the insertion protrusion 1441 inserted into the through hole 1410a, the insertion hole 1442 communicates with the insertion recess 1421. The insertion protrusion 1441 extends upward along the inner wall of the through hole 1410a to the lower surface of the electrode terminal 1420, thereby acting as a gasket. In other words, the insertion protrusion 1441 prevents electrolyte or gas inside the housing 1100 from leaking out of the housing 1100 and prevents external moisture or air from penetrating into the housing 1100.

[0085] like Figure 6 As illustrated, after constructing the cover assembly 1400_1, the current collecting protrusion 1320 of the current collector 1300 can be inserted into the insertion hole 1442 and the insertion recess 1421. Thereafter, as shown... Figure 7 As illustrated, welding W can be performed on the upper surface 1421a of the insertion recess 1421 of the electrode terminal 1420 to connect the electrode terminal 1420 and the current collector protrusion 1320 to each other.

[0086] According to the cover assembly 1400_1 of the first embodiment of this disclosure having the above-described structure, since the electrode terminal 1420 and the cover plate 1410 are welded and connected to the upper and lower surfaces of the upper insulating plate 1430 by an active brazing method, a rivet-free cover assembly can be constructed. In other words, the upper insulating plate 1430, including the filling metal layer 1432, can replace the function of a rivet, thereby reducing the number of components constituting the cover assembly 1400_1. Therefore, the total resistance of the secondary battery can be reduced, and space utilization can be improved. In addition, since welding is performed on the upper surface 1421a of the insertion recess 1421 of the electrode terminal 1420, there are no gaps at the welded portion and the welded portion is not exposed to the outside, thereby improving the sealing performance.

[0087] Figure 8 This is a cross-sectional view of the cover assembly according to a second embodiment of the present disclosure.

[0088] Reference Figure 8 The cover assembly 1400_2 according to the second embodiment of this disclosure may include a cover plate 1410, electrode terminals 1420, an upper insulating plate 1430, and a lower insulating plate 1440. Except for the shapes of the insertion recess 1421 and the current collecting protrusion 1320, which differ from the shapes of the insertion recess and current collecting protrusion in the first embodiment described above, the cover assembly 1400_2 is substantially the same as that in the first embodiment, and therefore its redundant description will be omitted.

[0089] In the second embodiment of this disclosure, a fitting groove 1422 may be formed in the inner peripheral surface of the insertion recess 1421 formed in the central portion of the electrode terminal 1420, and a fitting portion 1321 fitted into the fitting groove 1422 may be formed on the outer peripheral surface of the current collecting protrusion 1320.

[0090] The fitting slot 1422 can be formed into a tapered shape in which its width decreases from the lower portion to the upper portion. In addition, the fitting portion 1321 can be formed into a shape corresponding to the fitting slot 1422.

[0091] like Figure 8 As illustrated, after constructing the cover assembly 1400_2, the current collecting protrusion 1320 of the current collector 1300 can be inserted into the insertion hole 1442 and the insertion recess 1421. Thereafter, welding W can be performed on the upper surface 1421a of the electrode terminal 1420 insertion recess 1421 to connect the electrode terminal 1420 and the current collecting protrusion 1320 to each other.

[0092] In this case, since welding is performed after the mounting portion 1321 of the current collector protrusion 1320 is fastened to the mounting groove 1422 by fitting, the connection strength between the current collector 1300 and the electrode terminal 1420 can be enhanced.

[0093] In addition, since the fitting portion 1321 and the fitting groove 1422 are formed into a tapered shape that is narrower in the upper portion and wider in the lower portion, the friction between the fitting portion 1321 and the fitting groove 1421 can be minimized when the flow collecting protrusion 1320 is press-fitted into the insertion recess 1421, thereby facilitating the fitting operation.

[0094] Figure 9 This is a cross-sectional view of the cover assembly according to the third embodiment of the present disclosure.

[0095] Reference Figure 9 The cover assembly 1400_3 according to the third embodiment of this disclosure may include a cover plate 1410, an electrode terminal 1420, an upper insulating plate 1430, and a lower insulating plate 1440. Except for the shape of the current collecting protrusion 1320, which differs from the shape of the current collecting protrusion in the first embodiment described above, the cover assembly 1400_3 is substantially the same as that in the first embodiment, and therefore its redundant description will be omitted.

[0096] In the third embodiment of this disclosure, the flow-collecting protrusion 1320 can be formed as a truncated cone shape that is narrower at the upper portion and wider at the lower portion. In other words, the flow-collecting protrusion 1320 can be formed as a cylindrical shape whose diameter decreases from the lower portion to the upper portion.

[0097] The insertion hole 1442 can be formed such that the diameter of its upper portion is the same as the diameter of its lower portion. In this case, the diameter of the lower portion of the collecting protrusion 1320 can be formed to be larger than the diameter of the insertion hole 1442, so that the collecting protrusion 1320 can be force-fitted into the insertion hole 1442.

[0098] In the cover component 1400_3, such as Figure 9 After being constructed as illustrated, the current collector protrusion 1320 of the current collector 1300 can be inserted into the insertion hole 1442 and the insertion recess 1421, and then welding W can be performed on the upper surface 1421a of the insertion recess 1421 of the electrode terminal 1420 to connect the electrode terminal 1420 and the current collector protrusion 1320 to each other.

[0099] In this case, the current collector protrusion 1320 can be welded after being force-fitted into the insertion hole 1442 and the insertion recess 1421, thereby improving the connection strength between the current collector 1300 and the electrode terminal 1420.

[0100] Figure 10 This is a cross-sectional view of the cover assembly according to the fourth embodiment of the present disclosure. Figure 11This is a plan view of the ceramic layer of the cover assembly according to the fourth embodiment of the present disclosure. Figure 12 It is along Figure 11 A cross-sectional view taken from line A-A'.

[0101] Reference Figure 10 The cover assembly 1400_4 according to the fourth embodiment of this disclosure may include a cover plate 1410, electrode terminals 1420, an upper insulating plate 1430, and a lower insulating plate 1440. Except for the shape and manufacturing process of the upper insulating plate 1430, which differ from the shape and manufacturing process of the upper insulating plate in the first embodiment described above, the cover assembly 1400_4 is substantially the same as that in the first embodiment, and therefore its redundant description will be omitted.

[0102] In the fourth embodiment of this disclosure, the upper insulating plate 1430 may include a ceramic layer 1431 and a filler metal layer 1432 formed on the upper and lower surfaces of the ceramic layer 1431, and the ceramic layer 1431 may include at least one through hole 1431a or 1431b.

[0103] Reference Figure 11 Multiple through holes 1431a and 1431b can be formed radially around the center of the ceramic layer 1431. In this case, each through hole 1431a located near the center can be formed with a relatively small first diameter, and each through hole 1431b located away from the center can be formed with a second diameter larger than the first diameter.

[0104] Reference Figure 12 During the manufacturing process of the secondary battery, the filler metal layer 1432 may be formed only on the upper surface of the ceramic layer 1431. Additionally, a support member 1433 configured to support the lower surface of the ceramic layer 1431 may be formed on the cover plate 1410. The lower surface of the ceramic layer 1431 and the support member 1433 may define a space with a predetermined volume.

[0105] Then, when heat is applied at a temperature between the first melting point and the second melting point, the filler metal layer 1432 on the upper surface of the ceramic layer 1431 can be melted, and a portion of the molten filler metal layer 1432 can be firmly bonded to the ceramic layer 1431 and the electrode terminal 1420. Furthermore, the remaining portion of the molten filler metal layer 1432 can move through the through holes 1431a and 1431b to the space on the lower surface side of the ceramic layer 1431. Subsequently, when the molten filler metal layer 1432 solidifies by cooling, the filler metal layer 1432 can be formed on both the upper and lower surfaces of the ceramic layer 1431, and the lower portion of the filler metal layer 1432 can be firmly bonded to the cover plate 1410.

[0106] In this embodiment, since the upper filler metal layer 1432 and the lower filler metal layer 1432 are connected to each other through through holes 1431a and 1431b, the filler metal layer 1432 can be made of a material whose melting point is lower than that of aluminum and has insulating properties.

[0107] In other words, in this embodiment, the filler metal layer 1432 can be made of an aluminum-silicon based alloy, such as an Al-Si alloy, or an aluminum-zinc based alloy, such as an Al-Zn alloy, which have insulating properties. Alternatively, the filler metal layer 1432 can be made of a flux-based non-conductive brazing material, such as Al2O3 or B2O3, with a melting point in the range of about 400ºC to about 600ºC. Alternatively, a glass-ceramic brazing material with a melting point in the range of about 450ºC to about 600ºC can be used.

[0108] Figure 13 This is a view illustrating the process of connecting foil tabs to a current collector in a secondary battery according to an embodiment of the present disclosure. Figure 14 This is a view illustrating the process of connecting the cover assembly to the current collector in a secondary battery according to an embodiment of the present disclosure.

[0109] like Figure 13 and Figure 14 As illustrated, foil tabs 1220 and 1230 can be soldered to the corresponding current collector 1300. Each current collector 1300 can be mounted on a corresponding foil tab 1220 or 1230. Foil tabs 1220 and 1230 can be positioned so as not to interfere with each other. Therefore, the soldering position of foil tabs 1220 and 1230 can be located between the current collector 1300 and the insulator of the cover assembly 1400.

[0110] The current collector 1300 can be installed at the positive and negative terminals respectively. In this case, an insulator is placed below the current collector 1300, thereby electrically isolating the current collector 1300 from the electrode assembly.

[0111] Figure 15 This is a view illustrating the process of connecting a current collector to a foil in a secondary battery according to an embodiment of the present disclosure, where the foil is formed in opposite directions. Figure 16 This is a view illustrating the process of connecting each cover assembly to its corresponding collector. Figure 17 This is a view illustrating the process of attaching an insulator to an interconnected electrode assembly and current collector.

[0112] exist Figure 13 and Figure 14 In this configuration, both the foil contacts on the positive electrode and the foil contacts on the negative electrode are formed in the same direction. However, as... Figure 15 and Figure 16As illustrated, the electrode assembly can be configured such that the foil tabs on the positive electrode and the foil tabs on the negative electrode are formed in different directions. Therefore, the current collector 1300 can also be connected to the opposite side surface of the electrode assembly 1200.

[0113] like Figure 17 As illustrated, after the electrode assembly 1200 and the current collector 1300 are connected to each other, the first insulator I1 can be attached to the current collector 1300. Therefore, short circuits between the foil tab and the cover assembly 1400 can be prevented.

[0114] After the first insulator I1 is attached, the outer surface of the electrode assembly 1200 can be wrapped with the second insulator I2, and then the electrode assembly 1200 can be inserted into the housing 1100.

[0115] Subsequently, the outer surface of the box 1100 can be wrapped with a third insulator I3, thereby completing the manufacture of the secondary battery. Here, the first insulator I1 to the third insulator I3 can be formed from insulating tape or the like.

[0116] The structure of the insulating plate disclosed in this disclosure can be applied to cylindrical secondary batteries, and will be referred to Figure 18 and 19 Describe it.

[0117] Figure 18 This is a schematic cross-sectional view of a portion of a conventional cylindrical secondary battery. Figure 19 This is a schematic cross-sectional view of a portion of a cylindrical secondary battery with an insulating plate structure according to the present disclosure.

[0118] like Figure 18 As illustrated, a conventional cylindrical secondary battery includes a can-shaped casing 110 serving as the negative electrode and a terminal plate 120 serving as the positive electrode. The can-shaped casing 110 and the terminal plate 120 can be connected to each other by a riveting member 130.

[0119] like Figure 19 As illustrated, a cylindrical secondary battery employing the structure of an insulating plate according to this disclosure may include a can-shaped housing 110 serving as the negative electrode and a terminal plate 120 serving as the positive electrode. The can-shaped housing 110 and the terminal plate 120 may be connected to each other via an insulating plate 140.

[0120] The insulating plate 140 may have a stacked structure of a filler metal layer 1432 / ceramic layer 1431 / filler metal layer 1432. The upper filler metal layer 1432 may be brazed to the can-shaped housing 110, and the lower filler metal layer 1432 may be brazed to the terminal plate 120. In other words, the insulating plate 140 having the same structure as the stacked structure of filler metal layer 1432 / ceramic layer 1431 / filler metal layer 1432 can be applied to a cylindrical secondary battery, thereby constructing a rivetless cover assembly.

[0121] According to this disclosure, the total resistance of the secondary battery can be reduced, space utilization can be improved, and sealing performance can be enhanced by preventing welded parts from being exposed to the outside.

[0122] Although this disclosure has been described with reference to specific embodiments, it will be apparent to those skilled in the art that various changes or modifications may be made to this disclosure by adding, altering, or deleting components without departing from the spirit of this disclosure as defined in the appended claims. It should be noted that such changes or modifications also fall within the scope of this disclosure.

Claims

1. A secondary battery, comprising: A box, the box including an opening; An electrode assembly, which is inserted into the housing through the opening, and includes an electrode portion and a plurality of foil tabs formed on the electrode portion; as well as A cover assembly configured to seal the opening of the housing into which the electrode assembly is inserted. The cover assembly includes: Cover plate, the cover plate including through holes; An upper insulating plate, formed on the cover plate, comprising a ceramic layer and filler metal layers formed on the upper and lower surfaces of the ceramic layer; and Electrode terminals are formed on the upper insulating plate.

2. The secondary battery according to claim 1, in, The cover plate and the electrode terminals are each made of a metal having a first melting point, and The filling metal layer has a second melting point lower than the first melting point.

3. The secondary battery according to claim 2, wherein, The filler metal layer is made of an aluminum-silicon based alloy or an aluminum-germanium based alloy.

4. The secondary battery according to claim 3, wherein, The filler metal layer contains titanium, copper, or magnesium as additives.

5. The secondary battery according to claim 1, wherein, The secondary battery also includes a current collector, which includes a current collector body and a current collector protrusion. The electrode terminal includes an insertion recess in its central portion. The current collector protrusion is inserted into the insertion recess, and the insertion recess communicates with the through hole.

6. The secondary battery according to claim 5, wherein, A fitting groove is formed in the inner peripheral surface of the insertion recess, and a fitting portion fitting into the fitting groove is formed in the outer peripheral surface of the flow collecting protrusion.

7. The secondary battery according to claim 6, wherein, The fitting slot is formed into a tapered shape with its width decreasing upwards, and the fitting portion is formed into a shape corresponding to the fitting slot.

8. The secondary battery according to claim 1, wherein, The cover assembly also includes a lower insulating plate formed below the cover plate, the lower insulating plate including an insertion protrusion at its central portion that inserts into the through hole.

9. The secondary battery according to claim 8, wherein, The insertion protrusion is formed to extend upward along the inner wall of the through hole.

10. The secondary battery according to claim 8, wherein, The secondary battery also includes a current collector, which includes a current collector body and a current collector protrusion. The current collector protrusion is inserted into an insertion hole formed in the insertion protrusion and is formed in a cylindrical shape with a cross-section having a diameter that decreases from the lower portion to the upper portion.

11. The secondary battery according to claim 10, wherein, The diameter of the lower portion of the flow collecting protrusion is larger than the diameter of the insertion hole.

12. The secondary battery according to claim 5, wherein, The electrode terminals and the current collector protrusion inserted into the insertion recess are connected to each other by welding.

13. The secondary battery according to claim 1, wherein, The ceramic layer includes at least one through-hole.

14. The secondary battery according to claim 13, wherein, The filler metal layer includes at least one of aluminum-silicon based alloy, aluminum-zinc based alloy, flux-based non-conductive brazing material, and glass-ceramic brazing material.

15. The secondary battery according to claim 1, wherein, The plurality of foil tabs are formed along one direction of the electrode assembly.

16. The secondary battery according to claim 1, wherein, The plurality of foil tabs are formed in opposite directions along the electrode assembly.

17. The secondary battery according to claim 1, in, After the electrode assembly and the current collector are connected to each other, a first insulator is attached to the current collector. After the outer surface of the electrode assembly is wrapped with a second insulator, the electrode assembly is inserted into the box, and The outer surface of the box into which the electrode assembly is inserted is wrapped with a third insulator.

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