Secondary battery

Abstract

A secondary battery according to an embodiment of the present invention comprises a case, an electrode assembly and a cap assembly. An opening is formed in the case. The electrode assembly is inserted into the case through the opening, and has an electrode unit and a plurality of foil tabs formed on the electrode unit. The cap assembly seals the opening of the case into which the electrode assembly has been inserted. In addition, the cap assembly includes a cap plate, an upper insulating plate and an electrode terminal. A through-hole is formed in the cap plate. The upper insulating plate is disposed on the cap plate, and includes an insulating layer and a heat fusion layer formed on upper and lower surfaces of the insulating layer. The electrode terminal is formed on the upper insulating plate.

Description

secondary battery

[0001] The present invention relates to a secondary battery. The present application is filed with the Korean Intellectual Property Office on February 10, 2025, and is based on Korean Patent Application No. 10-2025-0016993, the contents of which are incorporated in whole into the present application by reference herein, and claims priority thereof.

[0002] Secondary batteries, which possess electrical characteristics such as high energy density and high applicability across product categories, are widely applied not only to portable devices but also to electric vehicles (EVs) and hybrid electric vehicles (HEVs) driven by electric power sources.

[0003] These secondary batteries are attracting attention as a new energy source for improving eco-friendliness and energy efficiency, as they not only have the primary advantage of being able to drastically reduce the use of fossil fuels but also the advantage of not generating any by-products from the use of energy.

[0004] Currently, widely used types of secondary batteries include lithium-ion batteries, lithium-polymer batteries, nickel-cadmium batteries, nickel-hydrogen batteries, and nickel-zinc batteries. The operating voltage of these unit secondary battery cells is approximately 2.5V to 4.5V.

[0005] Secondary batteries can be classified according to the shape of the battery case into can-type secondary batteries, in which the electrode assembly is embedded in a metal can, and pouch-type secondary batteries, in which the electrode assembly is embedded in a pouch of aluminum laminate sheets. Can-type secondary batteries can be classified into cylindrical secondary batteries and prismatic secondary batteries depending on the shape of the metal can.

[0006] The present invention provides a secondary battery comprising a cap assembly that can reduce the overall resistance of the secondary battery, improve space utilization, and improve sealing by preventing the welded portion from being exposed to the outside.

[0007] A secondary battery according to an embodiment of the present invention comprises a case, an electrode assembly, and a cap assembly. An opening is formed in the case. The electrode assembly is inserted into the case through the opening and is provided with an electrode portion and a plurality of foil tabs formed on the electrode portion. The cap assembly seals the opening of the case into which the electrode assembly is inserted. Furthermore, the cap assembly includes a cap plate, an upper insulating plate, and electrode terminals. A through hole is formed in the cap plate. The upper insulating plate is disposed on the upper part of the cap plate and includes an insulating layer and a heat-sealable layer formed on the upper and lower surfaces of the insulating layer. The electrode terminals are formed on the upper part of the upper insulating plate.

[0008] The above insulating layer may include a thermosetting resin, and the heat-fusion layer may include a thermoplastic resin.

[0009] The above heat-fused layer may be a modified polyolefin-based resin.

[0010] The surface of the above-mentioned thermal fusion layer can be treated with a plasma surface using plasma, treated with corona discharge using a high-voltage electric field, treated with a nano-coating using a coating agent containing nanoparticles, or treated with a fine pattern surface using a laser.

[0011] An insertion groove into which a current collecting projection of a current collecting plate is inserted may be formed in the center of the above electrode terminal, communicating with a through hole.

[0012] A fitting groove may be formed on the inner surface of the insertion groove, and a fitting part that fits into the fitting groove may be formed on the outer surface of the current collection projection.

[0013] The above-mentioned fitting groove is formed in a sloping shape with a width that decreases toward the top, and the fitting part can be formed in a shape corresponding to the fitting groove.

[0014] The above secondary battery may include a lower insulating plate formed at the bottom of the cap plate and having an insertion projection formed in the center that is inserted into a through hole. In this case, the insertion projection may be formed to extend upward along the inner wall of the through hole.

[0015] The above-mentioned current collecting projection is inserted into an insertion hole formed within an insertion projection, and its cross-section may be formed in a cylindrical shape such that the diameter decreases from the bottom to the top. At this time, the lower diameter of the current collecting projection may be formed to be larger than the diameter of the insertion hole.

[0016] After the current collecting projection is inserted into the above insertion groove, welding can be performed on the upper surface of the electrode terminal to combine the electrode terminal and the current collecting projection.

[0017] The above insulating layer may include at least one through-hole.

[0018] The above plurality of foil tabs can be formed in one direction of the electrode assembly.

[0019] The above plurality of foil tabs can be formed in both directions of the electrode assembly.

[0020] After the electrode assembly and the current collector plate are combined, a first insulating member may be attached to the current collector plate. Then, after the outer surface of the electrode assembly is wrapped with a second insulating member, the electrode assembly may be inserted into a case. Then, the outer surface of the case into which the electrode assembly is inserted may be wrapped with a third insulating member.

[0021] According to another embodiment of the present invention, an electric vehicle comprising the secondary battery is provided.

[0022] A cap assembly according to another embodiment of the present invention is a structure for sealing an opening of a secondary battery case, wherein the cap assembly comprises: a cap plate having a through hole formed therein; an upper insulating plate formed on the upper portion of the cap plate and including an insulating layer and a heat-fusion layer formed on the upper and lower surfaces of the insulating layer, respectively; and an electrode terminal formed on the upper portion of the upper insulating plate; wherein the cap plate is heat-fused and joined to the electrode terminal and the heat-fusion layers on the upper and lower surfaces, respectively.

[0023] The above insulating layer comprises a thermosetting resin, and the above upper and lower heat-fusion layers comprise a thermoplastic resin.

[0024] The surfaces of the thermal fusion layers on the upper and lower surfaces are treated with plasma surface treatment using plasma, corona discharge treatment using a high-voltage electric field, nano-coating treatment using a coating agent containing nanoparticles, or fine pattern surface treatment using a laser.

[0025] According to the present invention, the overall resistance of a secondary battery can be reduced, space utilization can be improved, and sealing can be improved by preventing the welded part from being exposed to the outside.

[0026] The following drawings attached to this specification illustrate embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings.

[0027] FIG. 1 is a cross-sectional view showing a cap assembly according to the prior art.

[0028] FIG. 2 is a perspective view showing a secondary battery according to one embodiment of the present invention.

[0029] FIG. 3 is a perspective view showing an exploded cap assembly in a secondary battery according to one embodiment of the present invention.

[0030] FIG. 4 is a perspective view showing an electrode assembly having a plurality of first and second foil tabs formed on an electrode portion in a secondary battery according to one embodiment of the present invention.

[0031] FIG. 5 is a drawing showing a first electrode plate in a secondary battery according to one embodiment of the present invention.

[0032] FIG. 6 is a drawing showing a second electrode plate in a secondary battery according to one embodiment of the present invention.

[0033] FIGS. 7 and FIGS. 8 are cross-sectional views illustrating a cap assembly according to a first embodiment of the present invention.

[0034] FIG. 9 is a cross-sectional view showing a cap assembly according to a second embodiment of the present invention.

[0035] FIG. 10 is a cross-sectional view showing a cap assembly according to a third embodiment of the present invention.

[0036] FIG. 11 is a cross-sectional view showing a cap assembly according to a fourth embodiment of the present invention.

[0037] FIG. 12 is a plan view showing the insulating layer of a cap assembly according to a fourth embodiment of the present invention.

[0038] Figure 13 is a cross-sectional view taken from the AA' line of Figure 12.

[0039] FIG. 14 is a drawing illustrating the process of combining a foil tab and a current collector plate in a secondary battery according to one embodiment of the present invention.

[0040] FIG. 15 is a drawing illustrating the process of combining a cap assembly and a current collector plate in a secondary battery according to one embodiment of the present invention.

[0041] FIG. 16 is a drawing illustrating the process of combining a current collector plate and a foil tab when the foil tab is formed in both directions in a secondary battery according to one embodiment of the present invention.

[0042] Figure 17 is a drawing illustrating the process of combining a cap assembly with a current collector plate.

[0043] FIG. 18 is a drawing illustrating the process of attaching an insulating member while the electrode assembly and the current collector plate are combined.

[0044] FIG. 19 is a schematic perspective view of an automobile including a secondary battery according to one embodiment of the present invention.

[0045] In parts of the attached drawings, corresponding components are given the same reference numerals. Those skilled in the art understand that the drawings are intended to illustrate elements simply and clearly and are not necessarily drawn to scale. For example, to aid in understanding various embodiments, the dimensions of some elements depicted in the drawings may be exaggerated compared to others. Additionally, elements of known technology that are useful or essential in commercially viable embodiments may often be omitted so as not to hinder the spirit of the various embodiments of the present invention.

[0046] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0047] The terms used in this invention are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this invention, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0048] Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

[0049] In a prismatic secondary battery, an electrode assembly is housed within a metal case, and a cap assembly is attached to the open end.

[0050] FIG. 1 is a cross-sectional view showing a cap assembly in a secondary battery according to the prior art.

[0051] As shown in FIG. 1, a cap assembly (10) according to the prior art is manufactured by inserting a current collecting projection (13) of a current collecting plate (12) into the hollow of a rivet (11), and then welding (W) the upper end (11a) of the rivet (11) and the upper end (13a) of the current collecting projection (13).

[0052] In the cap assembly (10) according to this conventional technology, the number of parts increases because a rivet (11) is used to combine the electrode terminal (14) and the cap plate (15), and consequently, the overall resistance of the secondary battery increases, and space utilization may be reduced due to the rivet (11).

[0053] In addition, the gap in the welded portion (W) may be exposed to the outside, and the electrolyte or gas inside the case may leak out through the exposed welded portion (W), and external moisture or air may penetrate into the case, which may degrade the efficiency of the battery.

[0054] Considering these points, the present invention provides a technology that can reduce the overall resistance of a secondary battery and improve space utilization by forming a heat-fused layer between, for example, electrode terminals in a cap assembly instead of using rivets, and improve sealing by preventing the welded area from being exposed to the outside.

[0055] FIG. 2 is a perspective view showing a secondary battery according to an embodiment of the present invention, FIG. 3 is a perspective view showing an exploded cap assembly in a secondary battery according to an embodiment of the present invention, FIG. 4 is a perspective view showing an electrode assembly having a plurality of first and second foil tabs formed on an electrode portion in a secondary battery according to an embodiment of the present invention, FIG. 5 is a drawing showing a first electrode plate in a secondary battery according to an embodiment of the present invention, and FIG. 6 is a drawing showing a second electrode plate in a secondary battery according to an embodiment of the present invention.

[0056] As illustrated in FIGS. 2 and 3, a secondary battery (1000) according to one embodiment of the present invention includes a case (1100), an electrode assembly (1200), a current collector plate (1300), and a cap assembly (1400).

[0057] The case (1100) forms the exterior of the secondary battery (1000). The case (1100) has a space formed inside to accommodate an electrode assembly (1200) and may have an opening formed on one side. In this embodiment, the case (1100) has a rectangular shape, but is not limited thereto and can be modified in various ways. The material of the case (1100) may be made of a rigid material capable of protecting the electrode assembly (1200) accommodated inside. For example, the case (1100) may be made of a metal such as aluminum or stainless steel.

[0058] An electrolyte may be contained within the case (1100) along with an electrode assembly (1200). The electrolyte may consist of a lithium salt such as LiPF6 or LiBF4 in an organic solvent such as EC, PC, DEC, EMC, or DMC. The electrolyte may be in a liquid, solid, or gel form.

[0059] The electrode assembly (1200) is housed inside the case (1100). As illustrated in FIG. 4, the electrode assembly (1200) according to one embodiment comprises an electrode portion (1210), a plurality of first foil tabs (1220), and a plurality of second foil tabs (1230). The plurality of first and second foil tabs (1220, 1230) are disposed at one end of the electrode portion (1210). In another embodiment, the first foil tab (1220) may be disposed on one side of the electrode portion (1210), and the second foil tab (1230) may be disposed on the other side of the electrode portion (1210). The plurality of first foil tabs (1220) are aligned with each other, and the plurality of second foil tabs (1230) are aligned with each other.

[0060] As shown in FIGS. 5 and 6, the electrode portion (1210) comprises a plurality of first electrode plates (1211), a plurality of second electrode plates (1212), and a separator.

[0061] An active material may be applied to a plurality of first electrode plates (1211) and a plurality of second electrode plates (1212). An active material, such as a transition metal oxide, may be applied to a metal plate such as aluminum on a plurality of first electrode plates (1211). A plurality of first electrode plates (1211) may be positive electrode plates. An active material, such as graphite or carbon, may be applied to a metal plate such as copper or nickel on a plurality of second electrode plates (1212). A plurality of second electrode plates (1212) may be negative electrode plates.

[0062] A separator (not shown) is positioned between a plurality of first and second electrode plates (1211, 1212) to prevent short circuits between the plurality of first and second electrode plates (1211, 1212). The material of the separator may be polyethylene, polypropylene, or a composite thereof.

[0063] The electrode portion (1210) can be formed by positioning a separator between a first electrode plate (1211) and a second electrode plate (1212) that are arranged sequentially. In one embodiment, the electrode portion (1210) can be formed by stacking the first electrode plate (1211), the separator, the second electrode plate (1212), and the separator in the order of tens to hundreds of times.

[0064] In this embodiment, the electrode assembly (1200) has one electrode part (1210), but in other embodiments, the electrode assembly (1200) may have a plurality of electrode parts (1210). The plurality of electrode parts (1210) may be electrically connected to each other.

[0065] A foil tab (1220, 1230) without active material applied is formed at one end of a plurality of first and second electrode plates (1211, 1212). In one embodiment, the electrode plates (1211, 1212) and the foil tabs (1220, 1230) may be formed integrally by cutting a predetermined portion of a metal plate using a laser or the like to leave the electrode plates (1211, 1212) and the foil tabs (1220, 1230). A plurality of foil tabs (1220, 1230) may be formed in a direction toward the cap assembly (1400).

[0066] When a plurality of first and second electrode plates (1211, 1212) are stacked, a plurality of first foil tabs (1220) overlap each other at a first position. A plurality of second foil tabs (1230) overlap each other at a second position. For example, a plurality of first foil tabs (1220) having the same polarity are grouped at a first position, and a plurality of second foil tabs (1230) are grouped at a second position. The first position and the second position are separated from each other on the electrode plates (1211, 1212), and the plurality of first foil tabs (1220) and the plurality of second foil tabs (1230) grouped together may be spaced apart in the longitudinal direction of the electrode assembly (1200).

[0067] Multiple foil tabs (1220, 1230) overlapped at each location can be connected to a current collector plate, such as by ultrasonic welding or laser welding, to facilitate the movement of current.

[0068] The collector plate (1300) is equipped with a collector body (1310) and a collector projection (1320).

[0069] A plurality of foil tabs (1220, 1230) are bent and welded to the current collecting body (1310). A current collecting projection (1320) is formed in the center of the current collecting body (1310).

[0070] The current collection projection (1320) protrudes upward from the upper surface of the current collection body (1310) and is coupled to the electrode terminal (1420) by welding or the like at the upper surface (1421a) of the insertion groove (1421) of the electrode terminal (1420) to electrically connect the electrode assembly and the electrode terminal (1420) (see FIG. 8). In another embodiment, the current collection projection (1320) of the current collection body (1310) is coupled to the terminal projection (1422, see FIG. 9) of the electrode terminal (1420) to electrically connect the electrode assembly (1200) and the electrode terminal (1420).

[0071] The current collector plate (1300) may be made of the same material as the plurality of foil tabs (1220, 1230) and may have a predetermined thickness, for example, about 0.8 mm to 1.2 mm. By using a current collector plate (1300) with a thick thickness, insulation effect and damage to the separator can be prevented or suppressed.

[0072] An insulating material may be placed on the lower part of the current collector plate (1300). The insulating material may be an insulating plate or an insulating film.

[0073] After welding multiple first foil tabs (1220) together and multiple second foil tabs (1230) together, a current collector plate (1300) is placed on each of the first foil tabs (1220) and the second foil tabs (1230).

[0074] After bending a plurality of first foil tabs (1220) and a plurality of second foil tabs (1230), a collector plate (1300) is welded on the plurality of first foil tabs (1220) and a plurality of second foil tabs (1230). The welding may be performed using methods such as ultrasonic welding or laser welding.

[0075] The cap assembly (1400) seals the opening of a case (1100) in which an electrode assembly (1200) is housed. In the present invention, the cap assembly (1400) is provided to reduce the overall resistance of the secondary battery, improve space utilization, and enhance sealing by preventing the welded portion from being exposed to the outside. Various embodiments of such a cap assembly (1400) will be described in detail with reference to FIGS. 7 through 14.

[0076] FIGS. 7 and FIGS. 8 are cross-sectional views illustrating a cap assembly according to a first embodiment of the present invention, FIG. 7 is a cross-sectional view illustrating a state in which the current collector plate (1300) is omitted, and FIG. 8 is a cross-sectional view illustrating a state in which the current collector plate (1300) is combined.

[0077] As illustrated in FIGS. 7 and 8, a cap assembly (1400_1) according to a first embodiment of the present invention may include a cap plate (1410), an electrode terminal (1420), an upper insulating plate (1430), and a lower insulating plate (1440).

[0078] The cap plate (1410) is in the shape of a plate that covers the opening of the case (1100) and has at least one through hole (1410a). The cap plate (1410) may have a shape corresponding to the shape of the opening of the case (1100). The cap plate (1410) may be formed of the same material as the case (1100), and the cap plate (1410) may be fixed to the case (1100) by a method such as laser welding.

[0079] A vent portion (1411) and an electrolyte injection port (1412) may be formed in the cap plate (1410). The vent portion (1411) opens when the internal pressure of the case (1100) exceeds a reference value. In this embodiment, the vent portion (1411) is formed in the cap plate (1410), but in other embodiments, the vent portion (1411) may be formed in the case (1100). Electrolyte can be injected into the interior of the case (1100) through the electrolyte injection port (1412).

[0080] The electrode terminal (1420) may be formed on the upper part of the cap plate (1410). The electrode terminal (1420) is electrically connected to the foil tab (1220) through the current collector plate (1300). The electrode terminal (1420) may be in the shape of a circular or square plate.

[0081] An insertion groove (1421) having a predetermined diameter is formed in the center of the electrode terminal (1420). The insertion groove (1421) is formed by being recessed upward from the central lower surface of the electrode terminal (1420). The insertion groove (1421) is formed in communication with the through hole (1410a) of the cap plate (1410). The upper surface (1421a) of the insertion groove (1421) is formed at a position higher than the upper insulating plate (1430). The current collecting projection (1320) of the current collecting plate (1300) can be inserted into the insertion groove (1421).

[0082] An upper insulating plate (1430) is placed between the electrode terminal (1420) and the cap plate (1410). The upper insulating plate (1430) insulates the electrode terminal (1420) and the cap plate (1410).

[0083] A first step (1430a) may be formed at the outer end of the upper insulating plate (1430), and a second step (1420a) corresponding to the first step (1430a) may be formed at the outer end of the electrode terminal (1420). As the second step (1420a) is fitted into the first step (1430a), the electrode terminal (1420) and the upper insulating plate (1430) can be easily joined.

[0084] In the present invention, a rivetless cap assembly can be formed by heat-fusing the cap plate (1410) and the electrode terminal (1420) to the upper and lower surfaces of the upper insulating plate (1430).

[0085] According to one embodiment, the upper insulating plate (1430) includes an insulating layer (1431) positioned in the center in the height direction and a heat-fusion layer (1432) formed on the upper and lower surfaces of the insulating layer (1431).

[0086] The insulating layer (1431) is used for electrical insulation, thermal management, mechanical protection, etc., inside or outside the secondary battery, and may be polypropylene (PP), polyamide (PA), polycarbonate (PC), polyethylene (PE), polyimide (PI), etc., having excellent electrical insulation, high chemical resistance (resistance to electrolyte), and heat resistance. Additionally, the insulating layer (1431) may include a thermosetting resin to maintain heat resistance even if a portion of the upper insulating plate (1430) melts.

[0087] The heat-fusion layer (1432) comprises a thermoplastic resin that melts when heated. The heat-fusion layer (1432) is formed on the upper and lower surfaces of the insulating layer (1431) and melts and solidifies when heated, so that the cap plate (1410) and the electrode terminal (1420) are heat-fused and joined on the upper and lower surfaces of the insulating layer (1431).

[0088] A modified polyolefin-based resin may be used as the heat-sealable layer (1432), for example, as a copolymer of ethylene or propylene and a monomer having a polar group, such as an ethylene / acrylic acid copolymer, an ethylene / methacrylic acid copolymer, an ethylene / ethyl acrylate copolymer, an ethylene-butyl acrylate copolymer, an ethylene-vinyl acetate copolymer, an ethylene / itaconic acid copolymer, an ethylene / monomethyl maleate copolymer, an ethylene / maleic acid copolymer, an ethylene / acrylic acid / methyl methacrylate copolymer, an ethylene / methacrylic acid / ethyl acrylate copolymer, an ethylene / monomethyl maleate / ethyl acrylate copolymer, an ethylene / methacrylic acid / vinyl acetate copolymer, an ethylene / acrylic acid / vinyl alcohol copolymer, an ethylene / propylene / acrylic acid copolymer, an ethylene / styrene / acrylic acid copolymer. Ethylene / methacrylic acid / acrylonitrile copolymer, ethylene / fumaric acid / vinylmethyl ether copolymer, ethylene / vinyl chloride / acrylic acid copolymer, ethylene / vinylidene chloride / acrylic acid copolymer, ethylene / trifluoroethylene / methacrylic acid copolymer, ethylene / sodium methacrylate salt copolymer, ethylene / zinc acrylate salt copolymer, ethylene / sodium styrene sulfonate salt copolymer, styrene-ethylene-propylene copolymer, propylene / acrylic acid copolymer, propylene / methacrylic acid copolymer, propylene / ethyl acrylate, propylene-butyl acrylate copolymer, propylene-vinyl acetate copolymer, propylene / itaconic acid copolymer, propylene / monomethyl maleate copolymer, propylene / maleic acid copolymer, propylene / acrylic acid / methyl methacrylate Copolymer, Propylene / Methacrylic Acid / Ethyl Acrylate Copolymer, Propylene / Monomethyl Maleate / Ethyl Acrylate Copolymer, Propylene / Methacrylic Acid / Vinyl Acetate Copolymer, Propylene / Acrylic Acid / Vinyl Alcohol Copolymer, Propylene / Propylene / Acrylic Acid Copolymer, Propylene / Styrene / Acrylic Acid Copolymer, Propylene / Methacrylic Acid / Acrylonitrile Copolymer, Propylene / Fumaric Acid / Vinyl Methyl Ether Copolymer, Propylene / Vinyl Chloride / Acrylic Acid Copolymer, Propylene / Vinylidene Chloride / Acrylic Acid Copolymer,Propylene / chlorotrifluoroethylene / methacrylic acid copolymer, propylene / sodium methacrylate salt copolymer, propylene / zinc acrylate salt copolymer, propylene / sodium styrene sulfonate salt copolymer, styrene-propylene-propylene copolymer, and substituted polyolefin resins which are maleic anhydride-grafted polyethylene or polypropylene, may be maleic anhydride-grafted high-density polyethylene (m-HDPE), maleic anhydride-grafted propylene (m-PP), maleic anhydride-grafted polyethylene / propylene copolymer (m-cpp), chlorinated polyethylene, polypropylene (CM), chlorosulfonated polyethylene or polypropylene (CSM).

[0089] Additionally, the surface of the heat fusion layer (1432) can be treated with a plasma surface using plasma, treated with corona discharge using a high-voltage electric field, treated with a nano-coating using a coating agent containing nanoparticles, or treated with a fine pattern surface using a laser, thereby improving the bonding strength between the upper heat fusion layer (1432) and the electrode terminal (1420) placed on top thereof, and the bonding strength between the lower heat fusion layer (1432) and the cap plate (1410) placed on bottom thereof.

[0090] A lower insulating plate (1440) is positioned at the bottom of a cap plate (1410). In the center of the lower insulating plate (1440), an insertion projection (1441) is formed, which is inserted into a through hole (1410a) and has an insertion hole (1442) formed inside. With the insertion projection (1441) inserted into the through hole (1410a), the insertion hole (1442) and the insertion groove (1421) are connected, and the current collecting projection (1320) of the current collecting plate (1300) is inserted into the insertion hole (1442) and the insertion groove (1421).

[0091] The insertion projection (1441) extends upward along the inner wall of the through hole (1410a) to the lower surface of the electrode terminal (1420) and performs the function of a gasket. For example, the insertion projection (1441) prevents or inhibits the leakage of electrolyte or gas inside the case (1100) to the outside, and prevents or inhibits moisture or air from the outside from penetrating into the case (1100).

[0092] After configuring the cap assembly (1400_1) as shown in FIG. 7, the current collecting protrusion (1320) of the current collecting plate (1300) is inserted into the insertion hole (1442) and the insertion groove (1421), and then welding (W) is performed on the upper surface of the electrode terminal (1420) as shown in FIG. 8 to combine the electrode terminal (1420) and the current collecting protrusion (1320).

[0093] According to the cap assembly (1400_1) according to the first embodiment of the present invention configured as described above, the cap plate (1410) and the electrode terminal (1420) are heat-fused and joined on the upper and lower surfaces of the upper insulating plate (1430), thereby enabling the formation of a rivet-free cap assembly. For example, the upper insulating plate (1430) can replace the function of a rivet, thereby reducing the number of parts forming the cap assembly (1400_1). Accordingly, the overall resistance of the secondary battery can be reduced, and space utilization can be improved. In addition, since welding is performed on the upper surface of the electrode terminal (1420), there are no gaps in the welded area and it is not exposed to the outside, thereby improving sealing performance. According to one embodiment, the welding can be performed by laser welding, etc.

[0094] FIG. 9 is a cross-sectional view showing a cap assembly according to a second embodiment of the present invention.

[0095] Referring to FIG. 9, the cap assembly (1400_2) according to the second embodiment of the present invention may include a cap plate (1410), an electrode terminal (1420), an upper insulating plate (1430), and a lower insulating plate (1440). Since the shape of the insertion groove (1421) and the current collection projection (1320) is different, and the rest is substantially the same as the first embodiment described above, a repeated description is omitted.

[0096] In the second embodiment, a fitting groove (1422) is formed on the inner surface of an insertion groove (1421) formed in the center of an electrode terminal (1420), and a fitting part (1321) that fits into the fitting groove (1422) may be formed on the outer surface of a current collecting projection (1320).

[0097] The insertion groove (1422) can be formed in a sloping shape that becomes narrower from the bottom to the top. Additionally, the insertion part (1321) can be formed in a shape corresponding to the insertion groove (1422).

[0098] After configuring the cap assembly (1400_2) as shown in FIG. 9, the current collecting protrusion (1320) of the current collecting plate (1300) is inserted into the insertion hole (1442) (see FIG. 8) and the insertion groove (1421), and then welding (W) is performed on the upper surface of the electrode terminal (1420) to combine the electrode terminal (1420) and the current collecting protrusion (1320).

[0099] At this time, since the fitting part (1321) of the current collector projection (1320) is welded in a state where it is fitted into the fitting groove (1422), the bonding strength between the current collector plate (1300) and the electrode terminal (1420) can be improved.

[0100] In addition, since the fitting part (1321) and the fitting groove (1422) are formed in a slanted shape that is narrower at the top and wider at the bottom, friction between the fitting part (1321) and the insertion groove (1421) is minimized when the current collection projection (1320) is forcibly fitted into the insertion groove (1421), and the fitting operation can be made easier.

[0101] FIG. 10 is a cross-sectional view showing a cap assembly according to a third embodiment of the present invention.

[0102] Referring to FIG. 10, the cap assembly (1400_3) according to the third embodiment of the present invention may include a cap plate (1410), an electrode terminal (1420), an upper insulating plate (1430), and a lower insulating plate (1440). Since the shape of the current collection protrusion (1320) is different, and the rest is substantially the same as the first embodiment described above, a repeated description is omitted.

[0103] In this third embodiment, the current collecting projection (1320) may be formed in a cylindrical shape having a cross-section that is narrower at the top and wider at the bottom. That is, the current collecting projection (1320) may be formed in a cylindrical shape in which the diameter decreases from the bottom to the top.

[0104] On the other hand, the insertion hole (1442) may be formed with the same diameter at the top and bottom. At this time, the current collection projection (1320) may be inserted into the insertion hole (1442) in a press-fit manner.

[0105] After configuring the cap assembly (1400_3) as shown in FIG. 10, the current collecting protrusion (1320) of the current collecting plate (1300) is inserted into the insertion hole (1442) and the insertion groove (1421), and then welding (W) is performed on the upper surface of the electrode terminal (1420) to combine the electrode terminal (1420) and the current collecting protrusion (1320).

[0106] At this time, the current collection protrusion (1320) is welded while inserted into the insertion hole (1442) and insertion groove (1421) in a press-fit manner, so the bonding strength between the current collection plate (1300) and the electrode terminal (1420) can be improved.

[0107]

[0108] FIG. 11 is a cross-sectional view showing a cap assembly according to a fourth embodiment of the present invention, FIG. 12 is a plan view showing an insulating layer of a cap assembly according to a fourth embodiment of the present invention, and FIG. 13 is a cross-sectional view viewed from the AA' line of FIG. 12.

[0109] Referring to FIG. 11, the cap assembly (1400_4) according to the fourth embodiment of the present invention may include a cap plate (1410), an electrode terminal (1420), an upper insulating plate (1430), and a lower insulating plate (1440). Since the shape and manufacturing process of the upper insulating plate (1430) are different, and the rest is substantially the same as the first embodiment described above, a repeated description is omitted.

[0110] In the fourth embodiment, the upper insulating plate (1430) includes an insulating layer (1431) and a heat-fused layer (1432) formed on the upper and lower surfaces thereof, and the insulating layer (1431) may include at least one through hole (1431a, 1431b).

[0111] Referring to FIG. 12, through holes (1431a, 1431b) may be formed in multiple numbers radially around the center of the insulating layer (1431). At this time, the through hole (1431a) closer to the center may be formed to have a relatively small first diameter, and the through hole (1431b) far from the center may be formed to have a second diameter larger than the first diameter.

[0112] Referring to FIG. 13, during the manufacturing process of the upper insulating plate (1430), a heat-fused layer (1432) may be formed only on the upper surface of the insulating layer (1431). Additionally, a support (1433) that supports the lower surface of the insulating layer (1431) may be formed on the cap plate (1410). The lower surface of the insulating layer (1431) and the support (1433) form a space of a predetermined volume.

[0113] When the material forming the heat-fusion layer (1432) is melted during the manufacturing process, at least a portion of the melted heat-fusion material may move to the space on the lower side of the insulating layer (1431) through the through holes (1431a, 1431b). Subsequently, when solidified by cooling, the heat-fusion layer (1432) may be formed on both the upper and lower surfaces of the insulating layer (1431).

[0114] FIG. 14 is a drawing illustrating the process of combining a foil tab and a current collector plate in a secondary battery according to one embodiment of the present invention, and FIG. 15 is a drawing illustrating the process of combining a cap assembly and a current collector plate in a secondary battery according to one embodiment of the present invention.

[0115] As illustrated in FIGS. 14 and 15, foil tabs (1220, 1230) are welded onto a collector plate (1300). On one collector plate (1300), the foil tabs (1220, 1230) rise up onto the collector plate from different directions centered around the collector projection (1320). The foil tabs (1220, 1230) can be positioned so as not to interfere with each other. Accordingly, the welding location of the foil tabs (1220, 1230) can be between the collector plate (1300) and the insulating member of the cap assembly (1400).

[0116] The current collector plate (1300) can be installed on each of the positive and negative electrodes. At this time, an insulating member is located at the bottom of the current collector plate so that the current collector plate and the electrode assembly are insulated.

[0117] FIG. 16 is a drawing illustrating the process of combining a current collector plate and a foil tab when a foil tab is formed in both directions in a secondary battery according to one embodiment of the present invention, FIG. 17 is a drawing illustrating the process of combining a cap assembly with a current collector plate, and FIG. 18 is a drawing illustrating the process of attaching an insulating member when the electrode assembly and the current collector plate are combined.

[0118] In FIGS. 14 and 15, the positive foil tab and the negative foil tab are both formed in the same direction. However, as shown in FIGS. 16 and 17, the electrode assembly may have the positive foil tab and the negative foil tab formed in different directions. Accordingly, the current collector plate (1300) may also be attached to both sides of the electrode assembly (1200).

[0119] Meanwhile, as shown in FIG. 18, a first insulating member (I1) can be attached to the current collector (1300) after the electrode assembly (1200) and the current collector (1300) are combined. This prevents a short circuit between the foil tab and the cap assembly (1400).

[0120] After attaching the first insulating member (I1), the outer surface of the electrode assembly (1200) is wrapped with the second insulating member (I2), and then the electrode assembly (1200) can be inserted into the case (1100).

[0121] Next, the manufacturing of the secondary battery can be completed by wrapping the outer surface of the case (1100) with a third insulating member (I3). Here, the first to third insulating members (I1 to I3) may be insulating tape, etc.

[0122] FIG. 19 is a schematic perspective view of an automobile including a secondary battery according to one embodiment of the present invention.

[0123] Referring to FIG. 19, a vehicle (30) according to one embodiment of the present invention may include one or more battery packs (20) that include one or more secondary batteries according to the aforementioned embodiments. The vehicle (30) according to the present invention may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle (30) includes various types of vehicles, such as four-wheeled vehicles, two-wheeled vehicles, or three-wheeled vehicles. The vehicle (30) may operate by receiving power from the battery pack (20) according to one embodiment of the present invention.

[0124] Although embodiments of the present invention have been described above, those skilled in the art may modify and change the present invention in various ways by adding, changing, deleting, or adding components, etc., without departing from the spirit of the present invention as described in the claims, and such modifications and changes are also to be included within the scope of the rights of the present invention.

Claims

1. A case in which an opening is formed; An electrode assembly inserted into the case through the opening and having an electrode portion and a plurality of foil tabs formed on the electrode portion; and It includes a cap assembly that seals the opening of the case into which the electrode assembly is inserted; wherein the cap assembly is Cap plate with a through hole formed therein; An upper insulating plate formed on the upper part of the above-mentioned cap plate and comprising an insulating layer and a heat-fusion layer formed on the upper and lower surfaces of the insulating layer; and A secondary battery comprising an electrode terminal formed on the upper portion of the upper insulating plate.

2. In Paragraph 1, A secondary battery in which the insulating layer comprises a thermosetting resin and the heat-fusion layer comprises a thermoplastic resin.

3. In Paragraph 2, The above heat-fused layer is a modified polyolefin-based resin in a secondary battery.

4. In Paragraph 1, The surface of the above-mentioned thermal fusion layer is treated with a plasma surface using plasma, treated with corona discharge using a high-voltage electric field, treated with a nanocoating using a coating agent containing nanoparticles, or treated with a micro-pattern surface using a laser for a secondary battery.

5. In Paragraph 1, A secondary battery in which an insertion groove into which a current collecting projection of a current collecting plate is inserted is formed in the center of the electrode terminal, communicating with the through hole.

6. In Paragraph 5, A secondary battery having a fitting groove formed on the inner surface of the insertion groove and a fitting part formed on the outer surface of the current collection projection to be fitted into the fitting groove.

7. In Paragraph 6, A secondary battery in which the above-mentioned fitting groove is formed in a sloping shape with a width that decreases toward the top, and the above-mentioned fitting portion is formed in a shape corresponding to the above-mentioned fitting groove.

8. In Paragraph 5, A secondary battery comprising a lower insulating plate formed on the lower part of the cap plate, with an insertion projection formed in the center that is inserted into the through hole.

9. In Paragraph 8, The above insertion projection is formed by extending upward along the inner wall of the through hole, forming a secondary battery.

10. In Paragraph 8, A secondary battery in which the above-mentioned current collection protrusion is inserted into an insertion hole formed within the above-mentioned insertion protrusion, and the cross-section thereof is formed in a cylindrical shape such that the diameter decreases from the bottom to the top.

11. In Paragraph 10, A secondary battery in which the lower diameter of the above-mentioned current collection protrusion is formed to be larger than the diameter of the above-mentioned insertion hole.

12. In Paragraph 5, A secondary battery in which, after the current collecting projection is inserted into the insertion groove, welding is performed on the upper surface of the electrode terminal to combine the electrode terminal and the current collecting projection.

13. In Paragraph 1, The above insulating layer is a secondary battery comprising at least one through-hole.

14. In Paragraph 1, The plurality of foil tabs above are formed in one direction of the electrode assembly, forming a secondary battery.

15. In Paragraph 1, The above plurality of foil tabs are formed in both directions of the electrode assembly in a secondary battery.

16. In Paragraph 1, After the electrode assembly and the current collector plate are combined, a first insulating material is attached to the current collector plate, and After the outer surface of the electrode assembly is wrapped with a second insulating material, the electrode assembly is inserted into the case, and A secondary battery in which the outer surface of the case into which the above electrode assembly is inserted is wrapped with a third insulating material.

17. An automobile comprising the secondary battery of paragraph 1.

18. A cap assembly for sealing the opening of a secondary battery case, wherein the cap assembly comprises: Cap plate with a through hole formed therein; An upper insulating plate formed on the upper part of the above-mentioned cap plate and comprising an insulating layer and a heat-fusion layer formed on the upper and lower surfaces of the insulating layer, respectively; and It includes an electrode terminal formed on the upper part of the upper insulating plate; and The above cap plate is a cap assembly joined by being heat-fused to the electrode terminal and the heat-fused layers of the upper and lower surfaces, respectively.

19. In Paragraph 18, A cap assembly in which the insulating layer comprises a thermosetting resin and the upper and lower heat-fusion layers comprise a thermoplastic resin.

20. In Paragraph 18, A cap assembly in which the surface of the heat-fusion layer on the upper and lower surfaces is treated with plasma surface treatment using plasma, corona discharge treatment using a high-voltage electric field, nano-coating treatment using a coating agent containing nanoparticles, or micro-pattern surface treatment using a laser.

Images