Manufacturing method of cylindrical lithium secondary battery, appratus for manufacturing cylindrical lithium secondary battery and cylindrical lithium secondary battery

Abstract

The present application relates to a method for manufacturing a cylindrical lithium secondary battery, an apparatus for manufacturing a cylindrical lithium secondary battery, and a cylindrical lithium secondary battery.

Description

Technology Field

[0001] The present application relates to a method for manufacturing a cylindrical lithium secondary battery, an apparatus for manufacturing a cylindrical lithium secondary battery, and a cylindrical lithium secondary battery. Background Technology

[0002] Due to the rapid increase in the use of fossil fuels, there is a growing demand for alternative or clean energy. As part of this effort, the fields of power generation and energy storage utilizing electrochemical reactions are the most actively researched.

[0003] Currently, a representative example of an electrochemical device utilizing such electrochemical energy is the secondary battery, and its scope of application is steadily expanding.

[0004] With the increasing technological development and demand for mobile devices, the demand for secondary batteries as an energy source is rapidly rising. Among these secondary batteries, lithium-ion batteries, which possess high energy density and voltage, long cycle life, and low self-discharge rates, have been commercialized and are widely used. Furthermore, active research is being conducted on methods to manufacture high-density electrodes with higher energy density per unit volume for use in such high-capacity lithium-ion batteries.

[0005] Generally, a secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. The negative electrode includes a negative electrode active material that inserts and extracts lithium ions from the positive electrode, and silicon-based particles with a large discharge capacity may be used as the negative electrode active material.

[0006] These lithium secondary batteries are typically manufactured using lithium-inserted compounds, such as LiCoO2 and LiMn2O4, for the positive electrode and non-lithium-inserted materials, such as carbon-based or silicon-based materials, for the negative electrode; during charging, lithium ions inserted in the positive electrode move to the negative electrode through the electrolyte, and during discharging, lithium ions move back from the negative electrode to the positive electrode.

[0007] Lithium-ion batteries are classified according to the shape of the battery case into cylindrical or prismatic batteries, in which the electrode assembly is housed in a cylindrical or prismatic metal can, and pouch-type batteries, in which the electrode assembly is housed in a pouch-type case made of aluminum laminate sheets. Among these, cylindrical batteries have the advantage of relatively high capacity and structural stability.

[0008] Generally, a cylindrical secondary battery includes a cylindrical electrode assembly, a cylindrical can that accommodates the electrode assembly and an electrolyte, and an upper cap assembly that is coupled to the upper opening of the can to seal the can and allow current generated from the electrode assembly to flow to an external device.

[0009] Looking briefly at the structure and manufacturing process of the aforementioned cylindrical secondary battery, the electrode assembly is formed by winding it into a jelly roll shape while the positive plate, separator, and negative plate are arranged in that order. Additionally, a cylindrical center pin is inserted into the center of the electrode assembly. This center pin prevents deformation of the electrode assembly and serves to discharge internal gases generated due to heat generation to the top of the battery. Furthermore, upper and lower insulating plates are formed on the top and bottom of the electrode assembly. These upper and lower insulating plates serve to prevent the electrode assembly from coming into contact with the upper cap assembly or the cylindrical can.

[0010] Such an electrode assembly is housed inside a cylindrical case, and a beading portion is formed on the upper side wall of the case to prevent the electrode assembly from moving inside the case. Additionally, a gasket is installed on the inner wall of the upper opening of the case to seat and connect the components and to seal the interior, and an upper cap assembly is installed inside the gasket to seal the upper opening of the can.

[0011] In order to prevent explosions when the secondary battery is overcharged, the above-mentioned cap assembly is equipped with a safety vent that deforms when the internal pressure changes due to overcharging, and a current interrupt device (CID), which collectively refers to a circuit board that cuts off the current due to the deformation of the safety vent.

[0012] Unlike prismatic or pouch-type secondary batteries, cylindrical secondary batteries configured as described above lack a separate device or process for removing internally generated gases during the manufacturing process. Consequently, there was a problem in that the current cutoff element could malfunction due to increased internal pressure caused by internal gas generation even before the product was shipped. In other words, since cylindrical secondary batteries undergo an activation process after assembly is complete, there is no separate provision for removing gases generated during this activation process. Because the aforementioned current cutoff element is a single-use device and cannot be restored, this resulted in the problem of product defects in the secondary battery prior to shipment.

[0013] Therefore, research is needed on a method to efficiently remove gas generated during the activation process in cylindrical secondary batteries. Prior art literature

[0014] Japanese Patent Publication No. 2009-080971 The problem to be solved

[0015] The present application relates to a method for manufacturing a cylindrical lithium secondary battery, an apparatus for manufacturing a cylindrical lithium secondary battery, and a cylindrical lithium secondary battery. means of solving the problem

[0016] One embodiment of the present specification provides a method for manufacturing a cylindrical lithium secondary battery, comprising the steps of: manufacturing a jellyroll electrode assembly by winding a laminated sheet of a positive electrode, a negative electrode, and a separator around a winding core; positioning the jellyroll electrode assembly inside a cylindrical can; welding a cap assembly to an opening of the cylindrical can; activating the cylindrical can; degassing the opening of the cylindrical can to lower the internal pressure of the cylindrical can; and restoring the swaged cylindrical can.

[0017] In another embodiment, an electrode assembly manufacturing unit that manufactures a jellyroll electrode assembly by winding a laminated sheet of an anode, a cathode, and a separator around a winding core;

[0018] The present invention provides an apparatus for manufacturing a cylindrical lithium secondary battery comprising: a conveying unit for conveying the above-manufactured jelly roll electrode assembly; an assembly unit for positioning and welding the above-manufactured jelly roll electrode assembly in a cylindrical can; an activation unit for activating the above-manufactured cylindrical can; and a degassing unit for lowering the internal pressure of the cylindrical can by swaging the opening of the above-manufactured cylindrical can.

[0019] Finally, one embodiment of the present application aims to provide a cylindrical lithium secondary battery manufactured according to the method for manufacturing a cylindrical lithium secondary battery according to the present application. Effects of the invention

[0020] The method for manufacturing a cylindrical lithium secondary battery according to the present application is characterized by including a degassing step after the steps of assembling and activating a cylindrical can, wherein the opening of the cylindrical can is swaged to lower the internal pressure of the cylindrical can. That is, rather than degassing by applying pressure to the entire assembled cylindrical can, the opening of the cylindrical can is swaged so as not to affect the interior of the cylindrical can, and by lowering the internal pressure of the cylindrical can through such a process, the method has the characteristic of being able to resolve problems such as CID short circuits caused by the increase in internal pressure due to gas generated during the activation process.

[0021] Generally, cylindrical secondary batteries are equipped with a CID as a safety device that prevents charging / discharging by insulating when a certain pressure is reached. Consequently, if high temperatures or high external pressures are repeatedly applied, the battery may operate even at pressures lower than the designed value. However, the manufacturing method of the cylindrical lithium secondary battery according to the present application involves swaging only the opening of the cylindrical can without affecting the interior of the can, rather than degassing by applying high pressure to the entire assembled cylindrical can. This allows for a reduction in internal pressure while simultaneously preventing high pressure from being transmitted to the exterior of the can, thereby increasing the reliability of guaranteeing the designed cycle performance. Specific details for implementing the invention

[0022] Before describing the present invention, we will first define some terms.

[0023] In this specification, when a part is described as "comprising" a certain component, it means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0024] In this specification, 'p to q' means a range of 'p or more and q or less'.

[0025] In this specification, "specific surface area" is measured by the BET method, specifically calculated from the amount of nitrogen gas adsorbed at a liquid nitrogen temperature (77K) using BELSORP-mino II of BEL Japan. That is, in this application, the BET specific surface area may refer to the specific surface area measured by the above measurement method.

[0026] In this specification, "Dn" refers to the particle size distribution and represents the particle size at the n% point of the cumulative distribution of the number of particles according to particle size. That is, D50 is the particle size (average particle size) at the 50% point of the cumulative distribution of the number of particles according to particle size, D90 is the particle size at the 90% point of the cumulative distribution of the number of particles according to particle size, and D10 is the particle size at the 10% point of the cumulative distribution of the number of particles according to particle size. Meanwhile, the particle size distribution can be measured using the laser diffraction method. Specifically, after dispersing the powder to be measured in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500) and the difference in diffraction patterns according to particle size is measured as the particles pass through the laser beam to calculate the particle size distribution.

[0027] In this specification, the meaning that a polymer contains a monomer in monomer units means that the monomer participates in a polymerization reaction and is included as a repeating unit within the polymer. In this specification, when it is stated that a polymer contains a monomer, this is interpreted as the same as the polymer containing the monomer in monomer units.

[0028] In this specification, the term "polymer" is understood to be used in a broad sense including copolymers unless specified as "homopolymer."

[0029] In this specification, the weight-average molecular weight (Mw) and the number-average molecular weight (Mn) are polystyrene equivalent molecular weights measured by gel permeation chromatography (GPC), using commercially available monodisperse polystyrene polymers of various degrees of polymerization (standard samples) for molecular weight measurement as standard materials. In this specification, the term "molecular weight" means weight-average molecular weight unless otherwise specified.

[0030] Hereinafter, the present invention will be described in detail with reference to the drawings so that those skilled in the art can easily practice the present invention. However, the present invention may be embodied in various different forms and is not limited to the description below.

[0031] One embodiment of the present specification provides a method for manufacturing a cylindrical lithium secondary battery, comprising the steps of: manufacturing a jellyroll electrode assembly by winding a laminated sheet of a positive electrode, a negative electrode, and a separator around a winding core; positioning the jellyroll electrode assembly inside a cylindrical can; welding a cap assembly to an opening of the cylindrical can; activating the cylindrical can; degassing the opening of the cylindrical can to lower the internal pressure of the cylindrical can; and restoring the swaged cylindrical can.

[0032] The method for manufacturing a cylindrical lithium secondary battery according to the present application is characterized by including a degassing step after the steps of assembling and activating a cylindrical can, wherein the opening of the cylindrical can is swaged to lower the internal pressure of the cylindrical can. That is, rather than degassing by applying pressure to the entire assembled cylindrical can, the opening of the cylindrical can is swaged so as not to affect the interior of the cylindrical can, and by lowering the internal pressure of the cylindrical can through such a process, the method has the characteristic of being able to resolve problems such as unusual CID short circuits caused by the increase in internal pressure due to gas generated during the activation process.

[0033] That is, the method for manufacturing a cylindrical lithium secondary battery according to the present application is characterized by including a specific degassing process, and specifically relates to a manufacturing method that can minimize damage to the assembled cylindrical can while simultaneously effectively controlling the gas generated inside the cylindrical can.

[0034] In one embodiment of the present application, a step of manufacturing a jellyroll electrode assembly by winding a laminated sheet of an anode, a cathode, and a separator around a winding core is provided.

[0035] In one embodiment of the present application, the electrode assembly comprises: an anode including an anode current collector; a cathode including a cathode current collector; and a separator between the anode and the cathode; and has a structure in which the electrode assembly is wound.

[0036] Specifically, according to one embodiment of the present application, the positive electrode may include a positive electrode current collector; and a positive electrode active material layer provided on one or both sides of the positive electrode current collector.

[0037] A cathode according to one embodiment of the present application may include a cathode current collector; and a cathode active material layer provided on one or both sides of the cathode current collector.

[0038] In one embodiment of the present application, the positive active material layer may comprise one or more selected from the group consisting of a positive active material; a positive conductive material; and a positive binder.

[0039] In one embodiment of the present application, the negative electrode active material layer may comprise one or more selected from the group consisting of a negative electrode active material; a negative electrode conductive material; and a negative electrode binder.

[0040] In one embodiment of the present application, the positive electrode active material may be a commonly used positive electrode active material. Specifically, the positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; a lithium iron oxide such as LiFe3O4; or a compound with the chemical formula Li 1+c 1Mn 2-c1 Lithium manganese oxides such as O4 (0≤c1≤0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7, etc.; chemical formula LiNi 1-c2 M c2 Ni-site type lithium nickel oxide represented by O2 (wherein M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, satisfying 0.01≤c2≤0.3); chemical formula LiMn 2-c3 M c3 Examples include lithium manganese composite oxides represented by O2 (where M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn and Ta, satisfying 0.01≤c3≤0.1) or Li2Mn3MO8 (where M is at least one selected from the group consisting of Fe, Co, Ni, Cu and Zn); and LiMn2O4 in which a portion of the Li in the chemical formula is substituted with alkaline earth metal ions, but are not limited thereto. The anode may also be Li-metal.

[0041] The above-described positive active material layer may include a positive conductive material and a positive binder together with the positive active material described above.

[0042] At this time, the positive electrode conductive material is used to impart conductivity to the electrode, and in the battery being constructed, any material that has electronic conductivity without causing chemical changes can be used without special limitations. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, or silver; conductive whiskey such as zinc oxide or potassium titanate; conductive metal oxide such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and one of these alone or a mixture of two or more may be used.

[0043] In addition, the anode binder serves to improve adhesion between anode active material particles and adhesion between the anode active material and the anode current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these alone or a mixture of two or more may be used.

[0044] In one embodiment of the present application, the active material composition may be a negative active material composition, and the negative active material composition may include one or more selected from the group consisting of a negative active material; a negative conductive material; and a negative binder.

[0045] In one embodiment of the present application, the negative electrode active material composition may include a negative electrode active material comprising one or more selected from the group consisting of silicon-based materials and carbon-based materials.

[0046] In addition, in one embodiment of the present application, the cathode active material composition may include a cathode conductive material; and a cathode binder.

[0047] In one embodiment of the present application, the cathode active material; the cathode conductive material; and the cathode binder may be any material used in the art without limitation.

[0048] The above-mentioned cathode binder may include at least one selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluororubber, polyacrylic acid, and materials in which the hydrogens thereof are substituted with Li, Na, or Ca, etc., and may also include various copolymers thereof.

[0049] The above-mentioned cathode conductive material is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, Farnes black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; conductive tubes such as carbon nanotubes; metal powders such as fluorocarbon, aluminum, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives may be used.

[0050] In one embodiment of the present application, the separator separates the negative electrode and the positive electrode and provides a pathway for the movement of lithium ions. Any separator commonly used in secondary batteries may be used without special limitations, and it is particularly desirable that it has low resistance to the movement of electrolyte ions and excellent electrolyte moisture retention capacity. Specifically, a porous polymer film, such as a porous polymer film made of a polyolefin-based polymer like an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof may be used. In addition, a conventional porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fibers or polyethylene terephthalate fibers, may be used. Furthermore, a coated separator containing a ceramic component or a polymer material may be used to ensure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

[0051] In one embodiment of the present application, the steps of: positioning the jelly roll electrode assembly inside a cylindrical can; and welding a cap assembly to an opening of the cylindrical can.

[0052] In one embodiment of the present application, the method may include the step of welding a cap assembly to the opening of the cylindrical can; or the step of positioning the jellyroll electrode assembly inside the cylindrical can; and the step of injecting an electrolyte into the cylindrical can containing the jellyroll electrode assembly.

[0053] In the case of a cylindrical secondary battery according to the present application, an electrode assembly can be placed in a cylindrical can, an electrolyte can be added, and then a cap assembly can be sealed.

[0054] In one embodiment of the present application, in the step of welding a cap assembly to the opening of the cylindrical can, any welding used in the art may be adopted without limitation as long as the welding can seal the cap assembly to the opening of the cylindrical can.

[0055] At this time, the above electrolyte may include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc., which can be used when manufacturing lithium secondary batteries, but is not limited to these.

[0056] Specifically, the electrolyte may include a non-aqueous organic solvent and a metal salt.

[0057] As the above-mentioned non-aqueous organic solvent, for example, aprotic organic solvents such as N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyl lactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolone, formamide, dimethylformamide, dioxolone, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxymethane, dioxolone derivative, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ether, methyl propionate, ethyl propionate, etc. may be used.

[0058] In particular, among the above carbonate-based organic solvents, ethylene carbonate and propylene carbonate, which are cyclic carbonates, are high-viscosity organic solvents with high dielectric constants that effectively dissociate lithium salts, so they can be used preferably. Furthermore, if low-viscosity, low-dielectric constant linear carbonates such as dimethyl carbonate and diethyl carbonate are mixed with these cyclic carbonates in appropriate proportions, an electrolyte with high electrical conductivity can be produced, making it even more preferable to use.

[0059] The metal salt mentioned above may be a lithium salt, and the lithium salt is a substance that dissolves well in the non-aqueous electrolyte; for example, as the anion of the lithium salt, F - , Cl - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , PF6-, (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , CF3CF2SO3- , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - One or more types selected from the group consisting of can be used.

[0060] In addition to the above electrolyte components, the above electrolyte may further include one or more additives for the purpose of improving the lifespan characteristics of the battery, suppressing the decrease in battery capacity, and improving the discharge capacity of the battery, such as, for example, a haloalkylene carbonate-based compound such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, triamide hexaphosphate, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, or aluminum trichloride.

[0061] In one embodiment of the present application, the step of activating the cylindrical can is included.

[0062] In one embodiment of the present application, the step of activating the cylindrical can is to activate the cylindrical can for 10 to 60 seconds in an atmosphere of 0 to 50°C, thereby providing a method for manufacturing a cylindrical lithium secondary battery.

[0063] In one embodiment of the present application, gas is generated in an electrode assembly contained within the cylindrical can through the activation of the cylindrical can, and the generated gas is contained within, causing the pressure inside the can to increase.

[0064] The method for manufacturing a cylindrical lithium secondary battery according to the present application is intended to solve the above-mentioned problems, and its main purpose is to solve the above problems by including the degassing process described below.

[0065] In one embodiment of the present application, a method for manufacturing a cylindrical lithium secondary battery is provided, comprising: a degassing step of lowering the internal pressure of the cylindrical can by swaging the opening of the cylindrical can; and a step of restoring the swaged cylindrical can.

[0066] In one embodiment of the present application, the degassing step comprises the steps of swaging the opening of the activated cylindrical can to deform it into an elliptical shape, discharging the gas formed in the activation step to lower the internal pressure of the cylindrical can, and swaging the opening to restore it to a cylindrical shape. A method for manufacturing a cylindrical lithium secondary battery is provided.

[0067] That is, the degassing step according to the present application comprises the step of swaging the opening of the activated cylindrical can to deform it into an elliptical shape, discharging the gas formed in the activation step to lower the internal pressure of the cylindrical can, and restoring the opening to a cylindrical shape by swaging it. It is characterized by deforming the opening of the cylindrical can into an elliptical shape by swaging it, rather than discharging the gas by applying pressure to the front of the cylindrical can.

[0068] Although gas can be removed when external pressure is applied to the front, cylindrical secondary batteries generally feature a CID as a safety device that insulates the battery to prevent charging or discharging when pressure exceeds a certain level. Consequently, if high temperatures or high external pressures are repeatedly applied, the battery may activate even at pressures lower than the designed value, leading to reliability issues with the cylindrical secondary battery.

[0069] In one embodiment of the present application, the pressure in the process of swaging the opening of the degassing step to deform it into an elliptical shape is 10 kgf / cm² 2 Below, preferably 5 kgf / cm² 2 It can satisfy the following range, and 3kgf / cm² 2 The above range can be satisfied.

[0070] The method for manufacturing a cylindrical lithium secondary battery according to the present application involves swaging only the opening of the cylindrical can to the pressure range, rather than degassing by applying high pressure to the entire assembled cylindrical can, so as not to affect the interior of the cylindrical can, thereby reducing internal pressure and simultaneously ensuring that high pressure is not transmitted to the exterior of the cylindrical can, thus increasing the reliability of guaranteeing the designed cycle performance.

[0071] Ultimately, the degassing step according to the present application involves swaging the upper part of the manufactured cylindrical can to equalize the increased internal pressure with the external pressure, and is characterized by the ability to remove the gas generated inside during the process.

[0072] In one embodiment of the present application, the degassing step is at atmospheric pressure (1 kgf / cm²). 2 A method for manufacturing a cylindrical lithium secondary battery is provided, which is applied in a ) atmosphere; a low vacuum atmosphere; or a medium vacuum atmosphere.

[0073] In the present application, the above atmosphere may refer to an external environment in which the cylindrical can is included.

[0074] In the present application, the above atmospheric pressure may refer to conditions of general atmospheric pressure, and 1 kgf / cm² 2 It may mean the conditions of, but is not limited to.

[0075] In the present application, the low vacuum atmosphere is a cylindrical can with a vacuum applied thereto, and the low vacuum may include the meaning of a generally used low vacuum, specifically meaning a range of 760 Torr to 1 Torr.

[0076] In the present application, the medium vacuum atmosphere is a vacuum applied to the cylindrical can, and the medium vacuum may include the meaning of a generally used low vacuum, specifically meaning a range of 1 / 1000 Torr to 1 / 10000000 Torr.

[0077] In one embodiment of the present application, the degassing process can be applied at atmospheric pressure, and in particular, when applied in a low vacuum atmosphere or a medium vacuum atmosphere, the internal pressure of the cylindrical can can be lowered more easily, thereby facilitating gas discharge, and in particular, the side reaction of oxygen and the electrode assembly contained inside the cylindrical can can also be suppressed.

[0078] In one embodiment of the present application, the degassing step is at atmospheric pressure (1 kgf / cm²). 2 It is applied in an atmosphere, and through the step of activating the cylindrical can, the internal pressure of the cylindrical can is 1.3 kfg / cm² 2 Above 3 kfg / cm 2 Satisfying the following range, the internal pressure of the cylindrical can through the degassing step is 1.2 kfg / cm² 2 A method for manufacturing a cylindrical lithium secondary battery that satisfies the following range is provided.

[0079] That is, the degassing step according to the present application was carried out in an atmospheric pressure atmosphere, and through the activation process, the internal pressure of the cylindrical can is 1.3 kfg / cm² 2 Above 3 kfg / cm 2 In the range below, the internal pressure of the cylindrical can is 1.5 kfg / cm² 2 Above 2 kfg / cm 2 In the range below, the internal pressure of the cylindrical can is 1.5 kfg / cm² 2 Above 1.7 kfg / cm 2 The following range may be formed, and through the degassing step, the internal pressure of the cylindrical can is 1.2 kfg / cm² 2 It can be reduced to the following range.

[0080] Specifically, by performing the degassing step in an atmospheric pressure atmosphere, the internal pressure of the cylindrical can can be lowered to the same level as the external atmospheric pressure conditions, and specifically, the internal pressure of the cylindrical can is 1.2 kfg / cm² 2 Below, 1.1 kfg / cm³ 2 Below, 1 kfg / cm² 2 It can be formed within the following range, 0.9 kfg / cm² 2 The above range can be satisfied.

[0081] In one embodiment of the present application, the degassing step is applied in a low vacuum atmosphere; or a medium vacuum atmosphere, and through the step of activating the cylindrical can, the internal pressure of the cylindrical can is 1.3 kfg / cm² 2 Above 3 kfg / cm 2 Satisfying the following range, the internal pressure of the cylindrical can through the degassing step is 0.5 kfg / cm² 2 A method for manufacturing a cylindrical lithium secondary battery that satisfies the following range is provided.

[0082] That is, the degassing step according to the present application is performed in a low vacuum or medium vacuum atmosphere, and through the activation process, the internal pressure of the cylindrical can is 1.3 kfg / cm² 2 Above 3 kfg / cm 2 In the range below, the internal pressure of the cylindrical can is 1.5 kfg / cm² 2 Above 2 kfg / cm 2 In the range below, the internal pressure of the cylindrical can is 1.5 kfg / cm² 2 Above 1.7 kfg / cm 2 The following range may be formed, and through the degassing step, the internal pressure of the cylindrical can is 0.5 gfg / cm² 2 It can be reduced to the following range.

[0083] Specifically, the degassing step is performed in a vacuum atmosphere (low vacuum or medium vacuum), thereby lowering the internal pressure of the cylindrical can to a level equivalent to that of an external vacuum condition; specifically, the internal pressure of the cylindrical can is 0.5 kfg / cm² 2 Below, 0.4 kfg / cm 2 Below, 0.3 kfg / cm 2 It can be formed within the following range, 0.1 kfg / cm² 2 The above range can be satisfied.

[0084] As can be seen from the above, especially when applied in a low vacuum or medium vacuum atmosphere, the internal pressure of the cylindrical can can be lowered more easily, facilitating gas discharge; furthermore, especially when conducted in a vacuum atmosphere, it has the characteristic of being able to suppress side reactions in which oxygen reacts with the electrode assembly contained inside the cylindrical can.

[0085] In one embodiment of the present application, a method for manufacturing a cylindrical lithium secondary battery is provided, wherein the degassing step is performed for 10 to 60 seconds in an atmosphere of 0 to 50°C.

[0086] In one embodiment of the present application, a method for manufacturing a cylindrical lithium secondary battery is provided, comprising the step of crimping the cylindrical can after the step of recovering the swaged cylindrical can.

[0087] A method for manufacturing a cylindrical lithium secondary battery according to one embodiment of the present application may be applied to all generally used methods for manufacturing cylindrical lithium secondary batteries, except that it includes a degassing process after the activation process as described above.

[0088] In one embodiment of the present application, an apparatus for manufacturing a cylindrical lithium secondary battery is provided, comprising: an electrode assembly manufacturing unit that manufactures a jellyroll electrode assembly by winding a laminated sheet of a positive electrode, a negative electrode, and a separator around a winding core; a transfer unit that transports the manufactured jellyroll electrode assembly; an assembly unit that positions and welds the jellyroll electrode assembly in a cylindrical can; an activation unit that activates the cylindrical can; and a degassing unit that lowers the internal pressure of the cylindrical can by swaging the opening of the cylindrical can.

[0089] In the above-described manufacturing apparatus, the internal composition included in each apparatus may be the same as described above.

[0090] In one embodiment of the present application, the degassing unit provides a manufacturing apparatus for a cylindrical lithium secondary battery comprising: a jig for fixing the cylindrical can; a pressure unit for applying pressure to the opening of the cylindrical can on the upper part of the jig; and a pressure limiting unit for controlling the pressure of the pressure unit.

[0091] The degassing unit according to the present application has a pressure unit that applies pressure to the opening of a cylindrical can, and is characterized by degassing by applying pressure within a specific range rather than applying high pressure as described above, and may additionally include a pressure limiting unit on the manufacturing device.

[0092] The pressure limiting unit according to the present application sets the pressure of the pressure unit to 10 kgf / cm² 2 Limiting to the following, preferably 8 kgf / cm² 2 Below, 5 kgf / cm² 2 It can be limited to the following.

[0093] Finally, one embodiment of the present application aims to provide a cylindrical lithium secondary battery manufactured according to the method for manufacturing a cylindrical lithium secondary battery according to the present application.

[0094] In the case of a lithium secondary battery manufactured according to the method for manufacturing a cylindrical lithium secondary battery according to the present application, the generated gas is more efficiently removed after the activation step, thereby lowering the internal pressure and having the advantage of being able to produce a battery with high reliability regarding the guarantee of cycle performance designed in the safety device.

[0095] Hereinafter, preferred embodiments are presented to aid in understanding the present invention; however, the above embodiments are merely illustrative of the description, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of the description, and that such variations and modifications fall within the scope of the appended claims.

Claims

Claim 1 A method for manufacturing a cylindrical lithium secondary battery comprising: a step of manufacturing a jellyroll electrode assembly by winding a laminated sheet of a positive electrode, a negative electrode, and a separator around a winding core; a step of positioning the jellyroll electrode assembly inside a cylindrical can; a step of welding a cap assembly to an opening of the cylindrical can; a step of activating the cylindrical can; a degassing step of lowering the internal pressure of the cylindrical can by swaging the opening of the cylindrical can; and a step of restoring the swaged cylindrical can. Claim 2 A method for manufacturing a cylindrical lithium secondary battery according to claim 1, wherein the degassing step comprises the step of swaging the opening of the activated cylindrical can to deform it into an elliptical shape, discharging the gas formed in the activation step to lower the internal pressure of the cylindrical can, and swaging the opening to restore it to a cylindrical shape. Claim 3 In claim 1, the degassing step is at atmospheric pressure (1 kgf / cm²). 2 A method for manufacturing a cylindrical lithium secondary battery applied in an atmosphere; a low vacuum atmosphere; or a medium vacuum atmosphere. Claim 4 In claim 3, the degassing step is at atmospheric pressure (1 kgf / cm²). 2 It is applied in an atmosphere, and through the step of activating the cylindrical can, the internal pressure of the cylindrical can is 1.3 kfg / cm² 2 Above 3 kfg / cm 2 Satisfying the following range, the internal pressure of the cylindrical can through the degassing step is 1.2 kfg / cm² 2 A method for manufacturing a cylindrical lithium secondary battery that satisfies the following ranges. Claim 5 In claim 3, the degassing step is applied in a low vacuum atmosphere; or a medium vacuum atmosphere, and through the step of activating the cylindrical can, the internal pressure of the cylindrical can is 1.3 kfg / cm² 2 Above 3 kfg / cm 2 Satisfying the following range, the internal pressure of the cylindrical can through the degassing step is 0.5 kfg / cm² 2 A method for manufacturing a cylindrical lithium secondary battery that satisfies the following ranges. Claim 6 A method for manufacturing a cylindrical lithium secondary battery according to claim 1, wherein the degassing step is to degassing for 10 to 60 seconds in an atmosphere of 0 to 50°C. Claim 7 A method for manufacturing a cylindrical lithium secondary battery according to claim 1, comprising the step of crimping the cylindrical can after the step of recovering the swaged cylindrical can. Claim 8 A method for manufacturing a cylindrical lithium secondary battery according to claim 1, wherein the step of activating the cylindrical can is to activate the cylindrical can in an atmosphere of 0°C to 50°C for 10 to 60 seconds. Claim 9 An apparatus for manufacturing a cylindrical lithium secondary battery, comprising: an electrode assembly manufacturing unit that manufactures a jellyroll electrode assembly by winding a laminated sheet of a positive electrode, a negative electrode, and a separator around a winding core; a conveying unit that conveys the manufactured jellyroll electrode assembly; an assembly unit that positions and welds the jellyroll electrode assembly in a cylindrical can; an activation unit that activates the cylindrical can; and a degassing unit that lowers the internal pressure of the cylindrical can by swaging the opening of the cylindrical can. Claim 10 The manufacturing apparatus for a cylindrical lithium secondary battery according to claim 9, wherein the degassing unit comprises: a jig for fixing the cylindrical can; a pressure unit for applying pressure to the opening of the cylindrical can on the upper part of the jig; and a pressure limiting unit for adjusting the pressure of the pressure unit. Claim 11 In claim 10, the pressure limiting unit sets the pressure of the pressure unit to 10 kgf / cm² 2 A manufacturing apparatus for cylindrical lithium secondary batteries that is limited to the following. Claim 12 A cylindrical lithium secondary battery manufactured according to the method for manufacturing a cylindrical lithium secondary battery according to any one of claims 1 to 8.