Sealed lithium secondary battery and manufacturing method thereof

Abstract

The present invention relates to a sealed lithium secondary battery and a manufacturing method thereof. More specifically, a sealed lithium secondary battery of the present invention comprises: an electrode assembly including a positive electrode terminal and a negative electrode terminal; a first case for accommodating a first portion of the electrode assembly; a second case for accommodating the remaining second portion of the electrode assembly; and a first weld line formed along a boundary between the first case and the second case. The first portion has a first thickness, the second portion has a second thickness, the thickness of the electrode assembly is substantially equal to the sum of the first thickness and the second thickness, and the upper surface of the first case and the upper surface of the second case are welded and thus form a sealed upper surface, thereby forming a sealed upper surface.

Description

Sealed lithium secondary battery and manufacturing method thereof

[0001] The present invention relates to a sealed lithium secondary battery and a method for manufacturing the same.

[0002] Recent industrial demands have led to the active development of batteries with high energy density and safety. For example, lithium-ion batteries are being used not only in information and communication devices, but also in the automotive sector. Safety is particularly important in the automotive sector, as it is directly related to life.

[0003] Meanwhile, lithium-ion batteries currently on the market contain electrolytes containing flammable organic dispersions, which pose a risk of overheating and fire in the event of a short circuit. Considering these issues, all-solid-state batteries, which replace the electrolyte with a solid electrolyte, are being proposed. By eliminating flammable organic dispersions, all-solid-state batteries significantly reduce the risk of fire or explosion in the event of a short circuit. Therefore, these all-solid-state batteries can significantly improve safety compared to lithium-ion batteries that use electrolytes.

[0004] The cathode layer of an all-solid-state battery contains, in addition to the cathode active material, a sulfide-based solid electrolyte with excellent ionic conductivity.

[0005] The problem to be solved by the present invention is to provide a sealed lithium secondary battery having a direct welding structure, thereby having low internal resistance and excellent rapid charging and heating characteristics.

[0006] Another problem to be solved by the present invention is to provide a sealed lithium secondary battery in which the parts used and manufacturing process are minimized by being sealed without a separate cap member.

[0007] Another problem that the present invention seeks to solve is to provide a method for manufacturing a sealed lithium secondary battery without a separate cap member.

[0008] A sealed lithium secondary battery according to the concept of the present invention may include: an electrode assembly including a positive terminal and a negative terminal; a first case accommodating a first portion of the electrode assembly; a second case accommodating a remaining second portion of the electrode assembly; and a first welding line formed along a boundary between the first case and the second case. The first portion may have a first thickness, the second portion may have a second thickness, and the thickness of the electrode assembly may be substantially equal to the sum of the first thickness and the second thickness. An upper surface of the first case and an upper surface of the second case may be welded to form a sealed upper surface of the sealed lithium secondary battery.

[0009] According to another concept of the present invention, a sealed lithium secondary battery may include: an electrode assembly including a positive terminal and a negative terminal; a first case accommodating a first portion of the electrode assembly; and a second case accommodating a remaining second portion of the electrode assembly. The first portion may have a first thickness, the second portion may have a second thickness, and the thickness of the electrode assembly may be substantially equal to the sum of the first thickness and the second thickness. The positive terminal may include: a first positive tab portion; a second positive tab portion, the first positive tab portion and the second positive tab portion being arranged in parallel in a length direction; and a positive lead attached to the first positive tab portion and the second positive tab portion. The first positive tab portion, the second positive tab portion, and the positive lead may be electrically connected to each other, and an upper surface of the first case and an upper surface of the second case may be welded to form a sealed upper surface of the sealed lithium secondary battery.

[0010] According to another concept of the present invention, a method for manufacturing a sealed lithium secondary battery comprises: an electrode assembly including a positive terminal and a negative terminal; a first case accommodating a first portion of the electrode assembly; and a second case accommodating a remaining second portion of the electrode assembly; the method may include accommodating the electrode assembly between the first case and the second case facing each other; and performing a first welding process along a boundary between the first case and the second case such that an upper surface of the first case and an upper surface of the second case are welded to form a sealed upper surface. The first portion may have a first thickness, the second portion may have a second thickness, and the thickness of the electrode assembly may be substantially equal to the sum of the first thickness and the second thickness.

[0011] A sealed lithium secondary battery according to one embodiment of the present invention has a direct welding structure, thereby having low internal resistance and excellent rapid charging characteristics and heat generation characteristics.

[0012] A sealed lithium secondary battery according to one embodiment of the present invention is sealed without a separate cap member, so that the parts used and the manufacturing process can be minimized.

[0013] An electrode assembly accommodated in a sealed lithium secondary battery according to one embodiment of the present invention has a pair of positive (or negative) tab portions bent in opposite directions, so that all electrodes within the electrode assembly can be electrically connected to each other with the positive (or negative) terminal.

[0014] A method for manufacturing a sealed lithium secondary battery according to one embodiment of the present invention can seal a lithium secondary battery without a separate cap member, thereby minimizing the parts used and the manufacturing process.

[0015] Figure 1 is a schematic diagram illustrating a lithium secondary battery according to embodiments of the present invention.

[0016] FIG. 2a is an exploded perspective view of a sealed lithium secondary battery according to embodiments of the present invention. FIG. 2b is a cross-sectional view of an electrode assembly accommodated in a sealed lithium secondary battery according to embodiments of the present invention.

[0017] Fig. 3a is a perspective view of a sealed lithium secondary battery according to one embodiment of the present invention. Fig. 3b is a cross-sectional view illustrating one section of the sealed lithium secondary battery of Fig. 3a. Fig. 3c is a plan view illustrating the upper surface of the sealed lithium secondary battery of Fig. 3a.

[0018] FIG. 4 is a cross-sectional view illustrating one section of a sealed lithium secondary battery according to another embodiment.

[0019] Fig. 5a is a perspective view of a sealed lithium secondary battery according to another embodiment of the present invention. Fig. 5b is a cross-sectional view illustrating one section of the sealed lithium secondary battery of Fig. 5a. Fig. 5c is a plan view illustrating the upper surface of the sealed lithium secondary battery of Fig. 5a.

[0020] FIG. 6 is a perspective view of an electrode assembly accommodated in a sealed lithium secondary battery according to one embodiment.

[0021] Fig. 7a is a cross-sectional view illustrating an anode constituting an electrode assembly according to one embodiment. Fig. 7b is a cross-sectional view illustrating an anode constituting an electrode assembly according to one embodiment.

[0022]

[0023] To fully understand the structure and effects of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and subject to various modifications. However, the description of these embodiments is provided solely to ensure a complete disclosure of the present invention and to fully inform those skilled in the art of the invention of the scope of the invention.

[0024] In this specification, when a component is referred to as being on another component, it means that it can be formed directly on the other component, or a third component may be interposed between them. Furthermore, in the drawings, the thicknesses of the components are exaggerated for the sake of clarity. Parts designated by the same reference numerals throughout the specification represent the same components.

[0025] Unless otherwise specified herein, the singular may also include the plural. Furthermore, unless otherwise specified, "A or B" may mean "including A, including B, or including A and B." As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components.

[0026] As used herein, “combination thereof” may mean mixtures, laminates, composites, copolymers, alloys, blends, and reaction products of the components.

[0027] Unless otherwise defined herein, the particle size may be the average particle size. In addition, the particle size refers to the average particle size (D50), which means the diameter of particles with a cumulative volume of 50% by volume in a particle size distribution. The average particle size (D50) can be measured by a method well known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope (TEM) photograph or a scanning electron microscope (SEM) photograph. Alternatively, the average particle size (D50) value can be obtained by measuring with a measuring device that utilizes dynamic light-scattering, performing data analysis to count the number of particles for each particle size range, and calculating from the counted number. Alternatively, the average particle size (D50) value can be obtained by measuring with a laser diffraction method. When measuring by laser diffraction, more specifically, after the particles to be measured are dispersed in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasonic waves of approximately 28 kHz at an output of 60 W, and the average particle size (D50) based on 50% of the particle size distribution in the measuring device can be calculated.

[0028]

[0029] Figure 1 is a schematic conceptual diagram illustrating a lithium secondary battery according to embodiments of the present invention. Referring to Figure 1, the lithium secondary battery may include a positive electrode (10), a negative electrode (20), a separator (30), and an electrolyte (ELL).

[0030] The positive electrode (10) and the negative electrode (20) may be spaced apart from each other with a separator (30) therebetween. The separator (30) may be placed between the positive electrode (10) and the negative electrode (20). The positive electrode (10), the negative electrode (20), and the separator (30) may be in contact with the electrolyte (ELL). The positive electrode (10), the negative electrode (20), and the separator (30) may be impregnated in the electrolyte (ELL).

[0031] The electrolyte (ELL) may be a medium for transferring lithium ions between the positive electrode (10) and the negative electrode (20). Within the electrolyte (ELL), the lithium ions may pass through the separator (30) and move toward the positive electrode (10) or the negative electrode (20).

[0032]

[0033] Bipolar (10)

[0034] A positive electrode (10) for a lithium secondary battery may include a current collector (COL1) and a positive electrode active material layer (AML1) formed on the current collector (COL1). The positive electrode active material layer (AML1) includes a positive electrode active material and may further include a binder and / or a conductive material.

[0035] For example, the anode (10) may further include an additive that can act as a sacrificial anode.

[0036] The content of the positive electrode active material in the positive electrode active material layer (AML1) may be 90 wt% to 99.5 wt% with respect to 100 wt% of the positive electrode active material layer (AML1). The contents of the binder and the conductive material may each be 0.5 wt% to 5 wt% with respect to 100 wt% of the positive electrode active material layer (AML1).

[0037] The above binder serves to adhere the positive electrode active material particles well to each other and also to adhere the positive electrode active material well to the current collector (COL1). Representative examples of the binder include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, etc.

[0038] The conductive material is used to provide conductivity to the electrode, and any material that does not cause chemical changes and is electronically conductive can be used in the battery. Examples of the conductive material include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube; metal-based materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0039] Al can be used as the current collector (COL1), but is not limited thereto.

[0040]

[0041] positive electrode active material

[0042] As the cathode active material in the cathode active material layer (AML1), a compound capable of reversible intercalation and deintercalation of lithium (lithiated intercalation compound) can be used. Specifically, one or more of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof can be used.

[0043] The above composite oxide may be a lithium transition metal composite oxide, and specific examples thereof include lithium nickel-based oxide, lithium cobalt-based oxide, lithium manganese-based oxide, lithium iron phosphate-based compound, cobalt-free nickel-manganese-based oxide, or a combination thereof.

[0044] As an example, a compound represented by any one of the following chemical formulas may be used: Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Lia Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3(0≤f≤2); Li a FePO4(0.90≤a≤1.8).

[0045] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; L 1 is Mn, Al or a combination thereof.

[0046] For example, the cathode active material may be a high-nickel cathode active material in which the nickel content is 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more and 99 mol% or less, based on 100 mol% of metals excluding lithium in the lithium transition metal composite oxide. The high-nickel cathode active material can realize high capacity and thus can be applied to high-capacity, high-density lithium secondary batteries.

[0047]

[0048] Cathode (20)

[0049] A negative electrode (20) for a lithium secondary battery includes a current collector (COL2) and a negative electrode active material layer (AML2) positioned on the current collector (COL2). The negative electrode active material layer (AML2) includes a negative electrode active material and may further include a binder and / or a conductive material.

[0050] For example, the negative active material layer (AML2) may include 90 to 99 wt% of the negative active material, 0.5 to 5 wt% of the binder, and 0 to 5 wt% of the conductive material.

[0051] The above binder serves to adhere the negative electrode active material particles well to each other and also to adhere the negative electrode active material well to the current collector (COL2). The binder may be a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof.

[0052] Examples of the non-aqueous binder include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or combinations thereof.

[0053] The above-mentioned aqueous binder may be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluoroelastomer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0054] When using an aqueous binder as the above-mentioned negative electrode binder, a cellulose-based compound capable of imparting viscosity may be further included. The cellulose-based compound may be a mixture of one or more of carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or an alkali metal salt thereof. The alkali metal may be Na, K, or Li.

[0055] The above dry binder is a polymeric material capable of being fiberized, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a combination thereof.

[0056] The conductive material is used to provide conductivity to the electrode, and any material that does not cause chemical changes and is electronically conductive can be used in the battery. Specific examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metal-based materials in the form of metal powder or metal fibers, including copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0057] The current collector (COL2) may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with a conductive metal, and combinations thereof.

[0058]

[0059] Negative active material

[0060] The negative active material in the negative active material layer (AML2) includes a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0061] The material capable of reversibly intercalating / deintercalating the lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite in an amorphous, plate-like, flake-like, spherical, or fibrous form, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0062] As the above lithium metal alloy, an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn can be used.

[0063] As the material capable of doping and dedoping the lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material may be used. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiOx (0 < x < 2), a Si-Q alloy (wherein Q is selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements (excluding Si), Group 15 elements, Group 16 elements, transition metals, rare earth elements, and combinations thereof), or a combination thereof. The Sn-based negative electrode active material may be Sn, SnO2, a Sn-based alloy, or a combination thereof.

[0064] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, the composite may include secondary particles (cores) in which silicon primary particles are assembled and an amorphous carbon coating layer (shell) positioned on the surface of the secondary particles. The amorphous carbon may also be positioned between the silicon primary particles, such that, for example, the silicon primary particles may be coated with amorphous carbon. The secondary particles may be dispersed and present in an amorphous carbon matrix.

[0065] The silicon-carbon composite may further comprise crystalline carbon. For example, the silicon-carbon composite may comprise a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer positioned on the surface of the core.

[0066] The above Si-based negative electrode active material or Sn-based negative electrode active material can be used in a mixture with a carbon-based negative electrode active material.

[0067]

[0068] Separator (30)

[0069] Depending on the type of lithium secondary battery, a separator (30) may be present between the positive electrode (10) and the negative electrode (20). As the separator (30), a multilayer film of two or more layers of polyethylene, polypropylene, polyvinylidene fluoride, or these may be used, and of course, a mixed multilayer film such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, or a polypropylene / polyethylene / polypropylene three-layer separator may be used.

[0070] The separator (30) may include a porous substrate and a coating layer including an organic material, an inorganic material, or a combination thereof located on one or both sides of the porous substrate.

[0071] The above porous substrate may be a polymer film formed of any one polymer selected from polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyacetal, polyamide, polyimide, polycarbonate, polyether ketone, polyarylether ketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene oxide, cyclic olefin copolymer, polyphenylene sulfide, polyethylene naphthalate, glass fiber, Teflon, and polytetrafluoroethylene, or a copolymer or mixture of two or more thereof.

[0072] The organic material may include a polyvinylidene fluoride polymer or a (meth)acrylic polymer.

[0073] The above inorganic materials are Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, It may include inorganic particles selected from, but not limited to, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0074] The organic and inorganic substances may be mixed and present in one coating layer, or a coating layer including an organic substance and a coating layer including an inorganic substance may be present in a laminated form.

[0075]

[0076] electrolyte

[0077] The lithium secondary battery according to embodiments of the present invention may include a liquid electrolyte, a solid electrolyte, or a combination thereof. In one embodiment, the liquid electrolyte may be an electrolyte (ELL) described below. In one embodiment, the solid electrolyte may include a sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics. The sulfide-based solid electrolyte may include, for example, Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m, n are positive numbers, capital letter “” is Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, capital letter “” is one of P, Si, Ge, B, Al, Ga In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I xIt may include at least one selected from (0≤x≤2).

[0078] Sulfide-based solid electrolytes include, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x (0≤x≤2) may be an argyrodite-type compound including at least one selected from. In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I. The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. Since the argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state battery is reduced, and the defect of the solid electrolyte membrane being penetrated and short-circuited due to the formation of lithium dendrites can be prevented. The elastic modulus of the solid electrolyte may be, for example, 15 GPa to 35 GPa.

[0079] Although not shown, the lithium secondary battery may include a solid electrolyte layer provided between the positive electrode (10) and the negative electrode (20) instead of the separator (30). For example, the solid electrolyte layer may include the above-described sulfide-based solid electrolyte.

[0080]

[0081] Electrolyte (ELL)

[0082] The electrolyte (ELL) for a lithium secondary battery contains a non-aqueous organic solvent and a lithium salt.

[0083] The above non-aqueous organic solvent acts as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0084] The above non-aqueous organic solvent may be a carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvent, an aprotic solvent, or a combination thereof.

[0085] Examples of the above carbonate solvents that can be used include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC).

[0086] Ester solvents that can be used include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanolide, mevalonolactone, valerolactone, and caprolactone.

[0087] Examples of ether solvents that can be used include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and tetrahydrofuran. In addition, examples of ketone solvents that can be used include cyclohexanone. Examples of alcohol solvents that can be used include ethyl alcohol and isopropyl alcohol, and examples of aprotic solvents that can be used include nitriles such as R-CN (where R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond, an aromatic ring, or an ether group); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane and 1,4-dioxolane; and sulfolanes.

[0088] The above non-aqueous organic solvents can be used alone or in combination of two or more.

[0089] In addition, when using a carbonate solvent, a cyclic carbonate and a chain carbonate can be mixed and used, and the cyclic carbonate and the chain carbonate can be mixed in a volume ratio of 1:1 to 1:9.

[0090] The above lithium salt is a substance that dissolves in an organic solvent and acts as a source of lithium ions in the battery, enabling the basic operation of a lithium secondary battery and promoting the movement of lithium ions between the positive and negative electrodes. Representative examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide (LiFSI), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2) (x and y are integers from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluoro(oxalato)borate (LiDFOB), lithium difluorobis(oxalato)phosphate (LiDFBOP), and lithium bis(oxalato)borate (LiBOB).

[0091]

[0092] sealed lithium secondary battery

[0093] FIG. 2a is an exploded perspective view illustrating a sealed lithium secondary battery according to embodiments of the present invention. FIG. 2b is a cross-sectional view illustrating an electrode assembly accommodated in a sealed lithium secondary battery according to embodiments of the present invention.

[0094] Referring to FIG. 2A, a sealed lithium secondary battery according to embodiments of the present invention includes a first case (CAS1), a second case (CAS2), and an electrode assembly (ESA). A first part (P1) of the electrode assembly (ESA) may be accommodated in the first case (CAS1), and the remaining second part (P2) may be accommodated in the second case (CAS2). The first part (P1) of the electrode assembly (ESA) may have a first thickness (TK1) in the width direction (WD), and the second part of the electrode assembly (ESA) may have a second thickness (TK2) in the width direction (WD). The electrode assembly (ESA) may have a third thickness (TK3) in the width direction (WD). The third thickness (TK3) of the electrode assembly may be substantially equal to the sum of the first thickness (TK1) and the second thickness (TK2).

[0095] The first case (CAS1) includes a first plate (PLT1). An electrode assembly receiving portion (EAR), a positive electrode groove (CEG), and a negative electrode groove (AEG) may be formed on the first plate (PLT1). In one embodiment, each of the positive electrode groove (CEG) and the negative electrode groove (AEG) may be formed on the upper surface of the first plate (PLT1).

[0096] The first case (CAS1) may include a first insulating member (ISM1) provided in the anode groove (CEG) and a second insulating member (ISM2) provided in the cathode groove (AEG). In one embodiment, the first insulating member (ISM1) may be attached to the inner surface of the anode groove (CEG). The second insulating member (ISM2) may be attached to the inner surface of the cathode groove (CEG).

[0097] The first insulating member (ISM1) can surround the inner surface of the anode groove (CEG). The second insulating member (ISM2) can surround the inner surface of the cathode groove (CEG).

[0098] A first case (CAS1) may include a first external terminal (OUT1) and a second external terminal (OUT2). In one embodiment, the first external terminal (OUT) may be provided on a first insulating member (ISM1). The second external terminal (OUT2) may be provided on a second insulating member (ISM2).

[0099] The second case (AS2) may have the same configuration as the first case (CAS1). The second case (CAS2) includes a second plate (PLT2). Like the first plate (PLT1), the second plate (PLT2) may be formed with an electrode assembly receiving portion (EAR), a positive electrode groove (CEG), and a negative electrode groove (AEG). In one embodiment, each of the positive electrode groove (CEG) and the negative electrode groove (AEG) may be formed on the upper surface of the second plate (PLT2).

[0100] The second case (CAS2) may include a first insulating member (ISM1) provided in the anode groove (CEG) and a second insulating member (ISM2) provided in the cathode groove (AEG). In one embodiment, the first insulating member (ISM1) may be attached to the inner surface of the anode groove (CEG). The second insulating member (ISM2) may be attached to the inner surface of the cathode groove (CEG). The first insulating member (ISM1) may surround the inner surface of the anode groove (CEG). The second insulating member (ISM2) may surround the inner surface of the cathode groove (CEG).

[0101] The second case (CAS2) may include a first external terminal (OUT1) and a second external terminal (OUT2), similar to the first case (CAS1). In one embodiment, the first external terminal (OUT) may be provided on the first insulating member (ISM1). The second external terminal (OUT2) may be provided on the second insulating member (ISM2).

[0102]

[0103] Referring to FIGS. 2A and 2B, the electrode assembly (ESA) may include an electrode stack, a positive electrode terminal (CNT), and a negative electrode terminal (ANT). The electrode stack may include a plurality of positive electrodes (10), separators (30), and negative electrodes (20) described with reference to FIG. 1. Alternatively, the electrode stack may include the solid electrolyte layer described above instead of the separator (30).

[0104] The positive terminal (CNT) may include a first positive tab portion (CTP1), a second positive tab portion (CTP2), and a positive lead (CLD).

[0105] In one embodiment, the positive electrode lead (CLD) may be attached to the first positive electrode tab portion (CTP1) and the second positive electrode tab portion (CTP2). Specifically, the positive electrode lead (CLD) may be welded to the first positive electrode tab portion (CTP1) and the second positive electrode tab portion (CTP2).

[0106] The first positive electrode tab portion (CTP1) and the second positive electrode tab portion (CTP2) can be arranged side by side in the length direction (LD).

[0107] Each of the first and second positive electrode tab portions (CTP1, CTP2) can be attached to the electrode laminate. Specifically, each of the first and second positive electrode tab portions (CTP1, CTP2) can be welded to the electrode laminate.

[0108] Each of the first and second positive electrode tabs (CTP1, CTP2) can be electrically connected to an electrode stack (EST).

[0109] The negative terminal (ANT) may include a first negative tab portion (ATP1), a second negative tab portion (ATP2), and a negative lead (ALD).

[0110] In one embodiment, the negative lead (ALD) may be attached to the first negative tab portion (ATP1) and the second negative tab portion (ATP2). Specifically, the negative lead (ALD) may be welded to the first negative tab portion (ATP1) and the second negative tab portion (ATP2).

[0111] The first negative tab portion (ATP1) and the second negative tab portion (ATP2) can be arranged parallel in the length direction (LD).

[0112] Each of the first and second negative tab portions (ATP1, ATP2) can be attached to an electrode stack (EST). Specifically, each of the first and second negative tab portions (ATP1, ATP2) can be welded to the electrode stack (EST).

[0113] Each of the first and second cathode tabs (ATP1, ATP2) can be electrically connected to an electrode stack (EST).

[0114]

[0115] FIG. 3A is a perspective view illustrating a sealed lithium secondary battery according to one embodiment of the present invention. FIG. 3B is a cross-sectional view illustrating one section (S) of the sealed lithium secondary battery of FIG. 3A. FIG. 3C is a plan view illustrating the upper surface of the sealed lithium secondary battery of FIG. 3A.

[0116] Referring to FIGS. 3A and 3C, the sealed lithium secondary battery may include a first welding line (WL1) formed along a boundary between a first case (CAS1) and a second case (CAS2). Specifically, the first welding line (WL1) may be formed along a boundary between a first plate (PLT1) and a second plate (PLT2) that face each other. For example, the first welding line (WL1) may be formed along side boundaries (SBR), a lower boundary (BBR), and an upper boundary (UBR) of the first plate (PLT1) and the second plate (PLT2). By having the first welding line (WL1) formed along the boundary between the first plate (PLT1) and the second plate (PLT2), the lithium secondary battery may be sealed without a separate cap plate covering the upper surfaces of the first case (CAS1) and the second case (CAS2).

[0117] Referring again to FIG. 3A, the upper surface of the first case (CAS1) and the upper surface of the second case (CAS2) may be welded to form a sealed upper surface of a sealed lithium secondary battery. In one embodiment, the upper surface of the first case (CAS1) and the upper surface of the second case (CAS2) may be welded to form a common surface. For example, the upper surface of the first plate (PLT1) of the first case (CAS1) and the upper surface of the second plate (PLT2) of the second case (CAS2) may be welded to form a sealed upper surface of a sealed lithium secondary battery.

[0118] In one embodiment, the upper surface of the first case (CAS1) may be the surface on which the first external terminal (OUT1) of the first case (CAS1) is located. The upper surface of the second case (CAS2) may be the surface on which the first external terminal (OUT1) of the second case (CAS2) is located. The upper surface of the sealed secondary battery may be the surface on which the first external terminal (OUT1) of the sealed secondary battery is located.

[0119] Referring to FIGS. 3B and 3C , in one embodiment, the sealed lithium secondary battery may include a second weld line (WL2) formed along a boundary between the first external terminal (OUT1) and the positive terminal (CNT) of the first case (CAS1). The sealed lithium secondary battery may further include a third weld line (WL3) formed along a boundary between the first external terminal (OUT1) and the positive terminal (CNT) of the second case (CAS2).

[0120] FIG. 4 is a cross-sectional view illustrating a cross-section (S) of a sealed lithium secondary battery for explaining a sealed lithium secondary battery according to another embodiment.

[0121] Referring to FIG. 4, the first plate (PLT1) of the first case (CAS1) may include a first lower contact surface (LCS1) that contacts the second plate (PLT2) of the second case (CAS2). The second plate (PLT2) of the second case (CAS2) may include a second lower contact surface (LCS2) that contacts the first plate (PLT1) of the first case (CAS1). The first lower contact surface (LCS1) and the second lower contact surface (LCS2) may face each other and contact each other.

[0122] In one embodiment, one of the first lower contact surface (LCS1) and the second lower contact surface (LCS2) may include a protrusion, and the other may include a concave portion corresponding to the protrusion. The protrusion and the concave portion may extend in the width direction (WD). For example, the first lower contact surface (LCS1) may include a concave portion, and the second lower contact surface (LCS2) may include a protrusion.

[0123] The first lower contact surface (LCS1) and the second lower contact surface (LCS2) each have a protrusion or a corresponding concave portion to prevent warping. This improves welding quality and prevents the occurrence of defective products.

[0124]

[0125] Fig. 5a is a perspective view illustrating a sealed lithium secondary battery according to another embodiment of the present invention. Fig. 5b is a cross-sectional view illustrating one section (S) of the sealed lithium secondary battery of Fig. 5a. Fig. 5c is a plan view illustrating the upper surface of the sealed lithium secondary battery of Fig. 5a.

[0126] Referring to FIGS. 5a and 5b, the first external terminal (OUT1) of the first case (CAS1) and the first external terminal (OUT1) of the second case (CAS2) may protrude higher than the positive terminal (CNT) in the height direction (HD).

[0127] Referring to FIG. 5B, the first external terminal (OUT1) of the first case (CAS1) may include a first inclined portion (SLP1) extending to the upper surface of the positive terminal (CNT). The first external terminal (OUT1) of the second case (CAS2) may include a second inclined portion (SLP2) extending to the upper surface of the positive terminal (CNT). The first inclined portion (SLP1) and the second inclined portion (SLP2) may face each other. The positive terminal (CNT) may be partially exposed between the first inclined portion (SLP1) and the second inclined portion (SLP2).

[0128] Referring to FIGS. 5b and 5c, in one embodiment, a fourth welding line (WL4) may be formed along a boundary between the first inclined portion (SLP1) and the second inclined portion (SLP). The fourth welding line (WL4) may be connected to the first welding line (WL1) in the longitudinal direction (LD).

[0129] Although not shown, the second external terminal (OUT2) of the first case (CAS1) and the second external terminal (OUT2) of the second case (CAS2) may protrude higher than the negative terminal (ANT) in the height direction (HD).

[0130] The second external terminal (OUT2) of the first case (CAS1) may include a third inclined portion extending toward the upper surface of the negative terminal (ANT). The second external terminal (OUT2) of the second case (CAS2) may include a fourth inclined portion extending toward the upper surface of the negative terminal (ANT). The third inclined portion and the fourth inclined portion may face each other. The negative terminal (ANT) may be partially exposed between the third inclined portion and the fourth inclined portion.

[0131] In one embodiment, a fourth welding line (WL4) may be formed along the boundary between the third and fourth inclined portions. The fourth welding line (WL4) may be connected to the first welding line (WL1) in the longitudinal direction (LD).

[0132]

[0133] Figure 6 is a perspective view illustrating an electrode assembly accommodated in a sealed lithium secondary battery.

[0134] Referring to FIG. 6, the electrode assembly (ESA) may include a positive terminal (CNT) and a negative terminal (ANT) previously described with reference to FIG. 2B. As described above, the positive terminal (CNT) may include a first positive tab portion (CTP1), a second positive tab portion (CTP2), and a positive lead (CLD). The negative terminal (ANT) may include a first negative tab portion (ATP1), a second negative tab portion (ATP2), and a negative lead (ALD).

[0135] The positive lead (CLD) may include a first connection portion (CNP1) attached to a first positive tab portion (CTP1), a second connection portion (CNP2) attached to a second positive tab portion (CTP2), and an outlet portion (INP). The outlet portion (INP) may connect the first connection portion (CNP1) and the second connection portion (CNP2) to each other. The outlet portion (INP) may be extended into a positive groove (CEG) of a first plate (PLT1) and a positive groove (CEG) of a second plate (PLT2). The outlet portion (INP) may be in contact with and electrically connected to a first external terminal (OUT1) of each of the first and second cases (CAS1, CAS2).

[0136] The negative lead (CLD) may also include a first connection portion (CNP1) attached to the first negative tab portion (ATP1), a second connection portion (CNP2) attached to the second negative tab portion (ATP2), and a lead portion (INP). The lead portion (INP) may connect the first connection portion (CNP1) and the second connection portion (CNP2) to each other. The lead portion (INP) may be led into the negative groove (AEG) of the first plate (PLT1) and the negative groove (AEG) of the second plate (PLT2). The lead portion (INP) may be in contact with and electrically connected to the first external terminal (OUT1) of each of the first and second cases (CAS1, CAS2).

[0137]

[0138] The first positive electrode tab portion (CTP1) and the second positive electrode tab portion (CTP2) can be arranged parallel in the length direction (LD).

[0139] In one embodiment, the first positive electrode tab portion (CTP1) may include a plurality of first positive electrode tabs (CTB1). The plurality of first positive electrode tabs (CTB1) may be arranged to be spaced apart in the width direction (WD). The second positive electrode tab portion (CTP2) may include a plurality of second positive electrode tabs (CTB2). The plurality of second positive electrode tabs (CTB2) may be arranged to be spaced apart in the width direction (WD).

[0140] Referring again to FIG. 6, in one embodiment, the plurality of first positive electrode tabs (CTB1) and the plurality of second positive electrode tabs (CTB2) may be bent. The plurality of first positive electrode tabs (CTB1) and the plurality of second positive electrode tabs (CTB2) may be bent in different directions. For example, the plurality of first positive electrode tabs (CTB1) may be bent in the a direction (WaD) of the width direction (WD). The plurality of second positive electrode tabs (CTB2) may be bent in the b direction (WbD) of the width direction (WD).

[0141] In one embodiment, a first positive electrode tab portion (CTP1) including bent first positive electrode tabs (CTB1) can be welded to a first connection portion (CNP1) of the positive electrode lead (CLD).

[0142] A second positive electrode tab portion (CTP2) including bent second positive electrode tabs (CTB2) can be welded to a second connection portion (CNP2) of the positive electrode lead (CLD).

[0143] FIG. 7A is a cross-sectional view illustrating a positive electrode (10) included in an electrode assembly (ESA) according to one embodiment. Referring to FIG. 7A, the positive electrode (10) may include a first positive electrode tab (CTB1) and a second positive electrode tab (CTB2). Since the positive electrode (10) includes first and second positive electrode tabs (CTB1, CTB2), when at least one of the first positive electrode tab (CTB1) and the second positive electrode tab (CTB2) is attached to the positive electrode terminal (CNT), the positive electrode (10) may be electrically connected to the positive electrode terminal (CNT). In one embodiment, the first positive electrode tab (CTB1) and the second positive electrode tab (CTB2) may be bent in opposite directions.

[0144] For example, referring again to FIG. 6, among the first positive electrode tabs (CTB1) bent in the a-direction (WaD), some of the first positive electrode tabs (CTB1) positioned at the outermost corner in the a-direction (WaD) may not be welded to the first connection portion (CNPT1) of the positive electrode lead (CLD). That is, the first positive electrode tabs (CTB1) of each of the positive electrodes (10) positioned at the outermost corner in the a-direction (WaD) may not be electrically connected to the positive electrode lead (CLD). However, since the second positive electrode tabs (CTB2) bent in the b-direction (WbD) are electrically connected to the positive electrode lead (CLD), as a result, some of the positive electrodes (10) positioned at the outermost corner in the a-direction (WaD) may also be electrically connected to the positive electrode lead (CLD). Similarly, among the second positive electrode tabs (CTB2) bent in the b direction (WbD), some of the second positive electrode tabs (CTB2) positioned at the outermost side in the b direction (WbD) may not be welded to the second connecting portion (CNPT2). That is, the second positive electrode tabs (CTB2) of each of the several positive electrodes (10) positioned at the outermost side in the b direction (WbD) may not be electrically connected to the positive electrode lead (CLD). However, since the first positive electrode tabs (CTB1) bent in the a direction (WaD) are electrically connected to the positive electrode lead (CLD), as a result, some of the positive electrodes (10) positioned at the outermost side in the b direction (WbD) may also be electrically connected to the positive electrode lead (CLD). Through this, all the anodes (10) within the electrode assembly (ESA) can be electrically connected to each other with the anode terminal (CNT), and similarly, all the cathodes (20) within the electrode assembly (ESA) can be electrically connected to each other with the cathode terminal (ANT).

[0145]

[0146] Hereinafter, a method for manufacturing a sealed secondary battery according to embodiments of the present invention will be described.

[0147] Referring to FIGS. 2A and 3A, a method for manufacturing a sealed secondary battery according to embodiments of the present invention may include: accommodating the electrode assembly (ESA) between a first case (CAS1) and a second case (CAS2) facing each other; and performing a first welding process along a boundary between the first case (CAS1) and the second case (CAS2) so that the upper surface of the first case (CAS1) and the upper surface of the second case (CAS2) are welded to form a sealed upper surface.

[0148] Referring to FIG. 2a, accommodating the electrode assembly (ESA) between the first case (CAS1) and the second case (CAS2) may specifically be such that the first part (P1) of the electrode assembly (ESA) is accommodated in the electrode assembly accommodation portion (EAR) of the first plate (PLT1), and the second part (P2) of the electrode assembly (ESA) is accommodated in the electrode assembly accommodation portion (EAR) of the second plate (PLT2).

[0149] In one embodiment, the upper surface of the first case (CAS1) may be the surface on which the first external terminal (OUT1) of the first case (CAS1) is located. The upper surface of the second case (CAS2) may be the surface on which the first external terminal (OUT1) of the second case (CAS2) is located. The upper surface of the sealed secondary battery may be the surface on which the first external terminal (OUT1) of the sealed secondary battery is located.

[0150] Referring to FIGS. 3A and 3B, before the first welding process, the positive terminal (CNT) of the electrode assembly (ESA) may be arranged side by side with the first external terminal (OUT1) of each of the first and second cases (CAS1, CAS2) along the width direction (WD). The positive terminal (CNT) of the electrode assembly (ESA) may be adjacent to the first external terminal (OUT1) of each of the first and second cases (CAS1, CAS2). Through this, the first external terminal (OUT1) of each of the first and second cases (CAS1, CAS2) and the positive terminal (CNT) of the electrode assembly (ESA) may be electrically connected to each other.

[0151] Performing the first welding process along the boundary between the first case (CAS1) and the second case (CAS2) may be, specifically, performing the first welding process along the boundary between the first plate (PLT1) of the first case (CAS1) and the second plate (PLT2) of the second case (CAS2). For example, the first welding process may be, for example, laser welding the left side, lower side, right side, and upper side boundaries between the first plate (PLT1) and the second plate (PLT2). Through this, the first welding line (WL1) may be formed. The laser welding may be performed continuously in a clockwise or counterclockwise direction.

[0152] Through the first welding process, the upper surface of the first case (CAS1) and the upper surface of the second case (CAS2) can be welded to form a sealed upper surface of a sealed lithium secondary battery.

[0153] In one embodiment, referring to FIG. 3C, the method for manufacturing a sealed lithium secondary battery may further include performing a second welding process. The second welding process may include welding along a boundary between a first external terminal (OUT1) and a positive terminal (CNT) of a first case (CAS1). The second welding process may include welding along a boundary between a second external terminal (OUT2) and a negative terminal (ANT) of the first case (CAS1). Through this, a second welding line (WL2) may be formed.

[0154] Referring to FIG. 3c, the method for manufacturing a sealed lithium secondary battery may further include performing a third welding process. The third welding process may include welding along a boundary between the first external terminal (OUT1) and the positive terminal (CNT) of the second case (CAS2). The third welding process may include welding along a boundary between the second external terminal (OUT2) and the negative terminal (ANT) of the second case (CAS2). Through this, a third welding line (WL3) may be formed.

[0155] In another embodiment, referring to FIGS. 5A to 5C, the method for manufacturing a sealed lithium secondary battery may not perform the second welding process and the third welding process. When the second and third welding processes are not performed, the first welding process may further include welding along a boundary between the first external terminal (OUT1) of the first case (CAS1) and the first external terminal (OUT1) of the second case (CAS2). In addition, the method may further include welding along a boundary between the second external terminal (OUT2) of the first case (CAS1) and the second external terminal (OUT2) of the second case (CAS2).

[0156] Specifically, the first external terminal (OUT1) of the first case (CAS1) and the first external terminal (OUT1) of the second case (CAS2) may each protrude higher than the positive terminal (CNT). In addition, the first external terminal (OUT1) of the first case (CAS1) and the first external terminal (OUT1) of the second case (CAS2) may each include an inclined portion extending toward the upper surface of the positive terminal (CNT). Similarly, the second external terminal (OUT2) of the first case (CAS1) and the second external terminal (OUT2) of the second case (CAS2) may each protrude higher than the negative terminal (ANT). In addition, the second external terminal (OUT2) of the first case (CAS1) and the second external terminal (OUT2) of the second case (CAS2) may each include an inclined portion extending toward the upper surface of the negative terminal (ANT). By having such a structure, when performing the first welding process along the upper surface boundary between the first plate (PLT1) and the second plate (PLT2), it is possible to continuously weld i) the boundary between the first external terminal (OUT1) of the first case (CAS1) and the first external terminal (OUT1) of the second case (CAS2); and ii) the boundary between the second external terminal (OUT2) of the first case (CAS1) and the second external terminal (OUT2) of the second case (CAS2) without changing the path.

[0157] i) a boundary between a first external terminal (OUT1) of a first case (CAS1) and a first external terminal (OUT1) of a second case (CAS2); and ii) a boundary between a second external terminal (OUT2) of a first case (CAS1) and a second external terminal (OUT2) of a second case (CAS2), and the fourth welding line (WL4) and the first welding line (WL1) may be formed as one welding line connected in the longitudinal direction (LD).

[0158] A method for manufacturing a sealed lithium secondary battery according to one embodiment may further include a process for forming an electrode terminal of an electrode assembly (ESA). The electrode terminal forming process may include a process for forming a positive terminal by welding a positive electrode lead (CLD) onto a first positive electrode tab portion (CTP1) and a second positive electrode tab portion (CTP2). Specifically, a first connection portion (CNP1) of the positive electrode lead (CLD) may be welded to the first positive electrode tab portion (CTP1), and a second connection portion (CNP2) may be welded to the second positive electrode tab portion (CTP2). Through this, a positive electrode terminal (CNT) including the first positive electrode tab portion (CTP1), the second positive electrode tab portion (CTP2), and the positive electrode lead (CLD) may be formed.

[0159] The electrode terminal forming process may include a negative terminal forming process of welding a negative lead (ALD) onto a first negative tab portion (ATP1) and a second negative tab portion (ATP2) of an electrode assembly (ESA). Specifically, the first connection portion (CNP1) of the negative lead (ALD) may be welded to the first negative tab portion (ATP1), and the second connection portion (CNP2) may be welded to the second negative tab portion (ATP2). Through this, a negative terminal (ANT) including the first negative tab portion (ATP1), the second negative tab portion (ATP2), and the negative lead (ALD) may be formed.

[0160] Referring to FIG. 6, a method for manufacturing a sealed lithium secondary battery according to one embodiment may include performing a tab processing process before the electrode terminal forming process.

[0161] The above tab processing process may include bending a plurality of first positive electrode tabs (CTB1); and bending a plurality of second positive electrode tabs (CTB2). Specifically, the tab processing process may bend the plurality of first positive electrode tabs (CTB1) and the plurality of second positive electrode tabs (CTB2) in opposite directions. For example, the plurality of first positive electrode tabs (CTB1) may be bent in an a direction (WaD) in the width direction (WD). The plurality of second positive electrode tabs (CTB2) may be bent in a b direction (WbD) in the width direction (WD).

[0162] The above tab processing process may further include bending a plurality of first negative electrode tabs (ATB1); and bending a plurality of second negative electrode tabs (ATB2). Specifically, the tab processing process may bend the plurality of first negative electrode tabs (ATB1) and the plurality of second negative electrode tabs (ATB2) in opposite directions. For example, the plurality of first negative electrode tabs (ATB1) may be bent in an a direction (WaD) in the width direction (WD). The plurality of second negative electrode tabs (ATB2) may be bent in a b direction (WbD) in the width direction (WD).

[0163] Through this, all the positive electrodes (10) and negative electrodes (20) in the electrode assembly (ESA) as described above can be electrically connected to each other with the positive electrode lead (CLD) and the negative electrode lead (ALD), respectively.

Claims

1. An electrode assembly including a positive terminal and a negative terminal; A first case accommodating a first portion of the electrode assembly; a second case accommodating the remaining second portion of the electrode assembly; and Including a first welding line formed along the boundary between the first case and the second case, The first portion has a first thickness, the second portion has a second thickness, and the thickness of the electrode assembly is substantially equal to the sum of the first thickness and the second thickness, A sealed lithium secondary battery, wherein the upper surface of the first case and the upper surface of the second case are welded to form a sealed upper surface.

2. In paragraph 1, Each of the above first and second cases: A plate including an electrode assembly receiving portion, an anode groove, and a cathode groove; An insulating member surrounding the inner surface of the above anode groove; and Including an external terminal on the above insulating member, A sealed lithium secondary battery, wherein the positive terminal of the electrode assembly is electrically connected to the external terminals of each of the first and second cases, positioned side by side along the width direction.

3. In paragraph 2, A second welding line formed along the boundary between the external terminal and the positive terminal of the first case; and A sealed lithium secondary battery further comprising a third welding line formed along a boundary between the external terminal of the second case and the positive terminal.

4. In paragraph 2, The plate of the first case includes a first lower contact surface, and the plate of the second case includes a second lower contact surface, The first lower contact surface and the second lower contact surface face each other and are in contact, The first lower contact surface includes a protrusion extending in the width direction, A sealed lithium secondary battery, wherein the second lower contact surface includes a concave portion corresponding to the protrusion.

5. In paragraph 2, Each of the external terminals of the first case and the external terminals of the second case protrude higher than the positive terminal, Each of the external terminals of the first case and the external terminals of the second case includes an inclined portion facing the upper surface of the positive terminal, A sealed lithium secondary battery further comprising a fourth welding line formed along a boundary between the inclined portion of the external terminal of the first case and the inclined portion of the external terminal of the second case.

6. In paragraph 5, A sealed lithium secondary battery, wherein the fourth welding line is connected longitudinally to the first welding line.

7. In paragraph 2, The above positive terminal: First positive electrode tab; The second anode tab portion, the first anode tab portion and the second anode tab portion are arranged longitudinally in parallel; and including a positive lead attached to the first positive tab portion and the second positive tab portion, A sealed lithium secondary battery, wherein the first positive electrode tab portion, the second positive electrode tab portion, and the positive electrode lead are electrically connected to each other.

8. In paragraph 7, The first anode tab portion includes a plurality of first anode tabs spaced apart from each other in the width direction, The second anode tab portion includes a plurality of second anode tabs spaced apart from each other in the width direction, A sealed lithium secondary battery, wherein the plurality of first positive electrode tabs and the plurality of second positive electrode tabs are bent in opposite directions.

9. In paragraph 7, The above positive lead is: A first connecting portion attached to the first positive electrode tab portion; a second connecting portion attached to the second positive electrode tab portion; and A sealed lithium secondary battery comprising a lead portion that is drawn out into the positive electrode groove while connecting the first connecting portion and the second connecting portion to each other.

10. An electrode assembly including a positive terminal and a negative terminal; a first case accommodating a first portion of the electrode assembly; and A second case comprising a second portion accommodating the remaining second portion of the electrode assembly, The first portion has a first thickness, the second portion has a second thickness, and the thickness of the electrode assembly is substantially equal to the sum of the first thickness and the second thickness, The above positive terminal: First positive electrode tab; The second anode tab portion, the first anode tab portion and the second anode tab portion are arranged longitudinally in parallel; and including a positive lead attached to the first positive tab portion and the second positive tab portion, The first positive electrode tab portion, the second positive electrode tab portion, and the positive electrode lead are electrically connected to each other, A sealed lithium secondary battery in which the upper surface of the first case and the upper surface of the second case are welded to form a sealed upper surface.

11. In paragraph 10, The first anode tab portion includes a plurality of first anode tabs spaced apart in the width direction, The second anode tab portion includes a plurality of second anode tabs spaced apart in the width direction, A sealed lithium secondary battery, wherein the plurality of first positive electrode tabs and the plurality of second positive electrode tabs are bent in opposite directions.

12. In paragraph 10, Each of the above first and second cases: A plate including an electrode assembly receiving portion, an anode groove, and a cathode groove; An insulating member surrounding the inner surface of the above anode groove; and Including an external terminal on the above insulating member, The positive terminal of the electrode assembly is electrically connected to the external terminals of each of the first and second cases, positioned side by side along the width direction, A sealed lithium secondary battery comprising a first welding line formed along a boundary between a plate of the first case and a plate of the second case.

13. In paragraph 12, A second welding line formed along the boundary between the external terminal and the positive terminal of the first case; and A sealed lithium secondary battery further comprising a third welding line formed along a boundary between the external terminal and the positive terminal of the second case.

14. In paragraph 12, Each of the external terminals of the first case and the external terminals of the second case protrude higher than the positive terminal, Each of the external terminals of the first case and the external terminals of the second case includes an inclined portion facing the upper surface of the positive terminal, A sealed lithium secondary battery further comprising a fourth welding line formed along a boundary between the inclined portion of the external terminal of the first case and the inclined portion of the external terminal of the second case.

15. Electrode assembly including a positive terminal and a negative terminal; a first case accommodating a first portion of the electrode assembly; and A method for manufacturing a sealed lithium secondary battery comprising a second case accommodating the remaining second part of the electrode assembly, The first portion has a first thickness, the second portion has a second thickness, and the thickness of the electrode assembly is substantially equal to the sum of the first thickness and the second thickness, Accommodating the electrode assembly between the first case and the second case facing each other; and A method for manufacturing a sealed lithium secondary battery, comprising performing a first welding process along a boundary between the first case and the second case so as to weld the upper surface of the first case and the upper surface of the second case to form a sealed upper surface.

16. In paragraph 15, Each of the above first and second cases: An insulating member surrounding the inner surface of the above anode groove; and Further comprising an external terminal on the insulating member, A method for manufacturing a sealed lithium secondary battery, further comprising, before the first welding process, arranging the positive terminal of the electrode assembly so that it is positioned side by side with the external terminal of each of the first and second cases in the width direction.

17. In paragraph 16, Performing a second welding process along the boundary between the external terminal and the positive terminal of the first case; and A method for manufacturing a sealed lithium secondary battery, further comprising performing a third welding process along a boundary between the external terminal and the positive terminal of the second case.

18. In paragraph 16, The external terminal of the first case and the external terminal of the second case protrude higher than the positive terminal, Each of the external terminals of the first case and the external terminals of the second case includes an inclined portion extending to the upper surface of the positive terminal, A method for manufacturing a sealed lithium secondary battery, wherein the first welding process further includes welding along a boundary between the external terminal of the first case and the external terminal of the second case.

19. In paragraph 15, The electrode assembly includes a first positive electrode tab portion and a second positive electrode tab portion arranged longitudinally side by side, A method for manufacturing a sealed lithium secondary battery, further comprising a positive terminal forming process of welding the positive lead onto the first positive tab portion and the second positive tab portion.

20. In paragraph 19, The first anode tab portion includes a plurality of first anode tabs spaced apart in the width direction, The second anode tab portion includes a plurality of second anode tabs spaced apart in the width direction, It may include performing a tab processing process before performing the above positive terminal forming process. The above tap processing process is: Bending the plurality of first anode tabs in the a direction; and comprising bending the plurality of second anode tabs in the b direction, A method for manufacturing a sealed lithium secondary battery, wherein the a direction and the b direction are opposite to each other.

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