KR20210088179A - Method of preparing electrode assembly comprising at least two distinct separator an electrode assembly manufactured thereby - Google Patents

Abstract

The present invention provides a method for manufacturing an electrode assembly including at least two kinds of separators and the electrode assembly using the same, wherein the electrode assembly includes at least two kinds of separators, has excellent electrolyte impregnation properties of the electrode assembly and high density and high density, and gives less damage to the separator when forming the electrode assembly.

Description

Method of preparing electrode assembly comprising at least two distinct separator an electrode assembly manufactured thereby

The present invention relates to a method for manufacturing an electrode assembly including at least two kinds of separators, and an electrode assembly according thereto. Specifically, the present invention relates to a method for manufacturing an electrode assembly using a wet separator for the outermost portion of an electrode assembly, and a dry separator for the portion excluding the outermost portion, and an electrode assembly according thereto.

Secondary batteries that can be charged and discharged are being used as alternative sources of various petroleum and fossil fuels such as mobile devices, electric vehicles, and hybrid electric vehicles.

As the field of using secondary batteries increases, high-output, high-capacity secondary batteries are required. In order to meet the demand, an electrode assembly in which a plurality of positive and negative plates and separators are stacked is being manufactured. One battery module is formed by electrically connecting the electrode assembly, and one battery pack is constituted by collecting the battery modules.

The electrode assembly may be transferred from one manufacturing line to another during the assembly process. In order to transport the electrode assembly to another place, a device called a Pick and Place (P&P) is used. The pick and place adsorbs one surface of the electrode assembly, and then transfers the electrode assembly to another location or changes the direction of the electrode assembly.

In order for the pick and place to adsorb the electrode assembly, a strong suction force is needed momentarily. Due to the strong suction force, the outermost surface of the electrode assembly, that is, the surface adsorbed by the pick and place may be damaged. In particular, in the case of an electrode assembly for forming a battery having a large capacity, the outermost surface is easily damaged by its width and weight.

If the separator, which is the outermost surface of the battery, is damaged, the safety of the battery may be compromised due to poor insulation or the like. In order to prevent this, the electrode assembly according to the prior art may wrap the entire exterior of the electrode assembly with a separator or a separator film, as shown in FIG. 1 . As can be seen in FIG. 1 , in the related art, a positive electrode 11 , a separator, and a negative electrode 13 are laminated to form a laminate, and then the laminate is wrapped with a separation film 14 to form an electrode assembly 10 . In this case, the separation film 14 may be replaced with the existing separation film 12 . However, since the electrode assembly 10 has a shape in which the side portion is blocked by the separation film 14 as shown in FIG. 1 , penetration of the electrolyte is difficult.

In the case of Patent Document 1, although the second separator to which a high tensile force is applied during winding is provided as a wet separator, this relates to a cylindrical battery, and since the separator is placed inside, the direction of the electrode assembly can be changed or other places as in the present invention. They do not recognize the problems that occur during movement.

In the case of Patent Document 2, in order to suppress a short circuit when the electrode assembly is damaged by foreign substances, the stretching direction of the two-layer separator is different, but the direction of the electrode assembly is changed in that several separators are used between each electrode. Or, it does not solve the problem of membrane damage that occurs when moving to another location.

As such, while preventing damage to the separator that may occur during direction change or transport, a technology for providing an electrode assembly having excellent electrolyte impregnation property and high density has not been provided yet.

Republic of Korea Patent Publication No. 2015-0071251 (2015.06.26) Japanese Patent Laid-Open No. 2018-49758 (2018.03.29)

The present invention is intended to solve the above problems, and specifically, in a stacked electrode assembly, the electrolyte impregnation property is excellent and the density is high, and the separation membrane is not damaged when changing the direction of the electrode assembly or moving it to another place, at least An object of the present invention is to provide a method for manufacturing an electrode assembly including two types of separators and an electrode assembly according thereto.

In order to achieve this object, the present invention provides (S1) a first unit cell comprising a first separator, a first electrode, a second separator, a second electrode, a third separator, and a first electrode; and a second unit cell including a fourth separator, a second electrode, and a fifth separator; (S2) forming an electrode assembly by stacking the second unit cell on the outermost first electrode of the first unit cell so that the fourth separator faces each other, wherein the first separator is a wet separator , The second separator, the third separator, and the fourth separator provide a method of manufacturing an electrode assembly in which the dry separator is a dry separator. In addition, the fifth separation membrane may be a wet separation membrane.

between the step (S1) and the step (S2), (S1-1) forming a third unit cell including a sixth separator, a second electrode, a seventh separator, and a first electrode; (S1-2) stacking one or more of the third unit cells on the outermost first electrode of the first unit cell so that the sixth separator faces each other.

One or more of the third unit cells may exist between the first unit cell and the second unit cell.

The sixth separator and the seventh separator may be dry separators.

In step (S2), the electrode assembly may have a stack type or a lamination/stack type structure.

The wet separation membrane may be manufactured by biaxial stretching, and the dry separation membrane may be manufactured by uniaxial stretching.

The present invention may be an electrode assembly manufactured according to the method for manufacturing an electrode assembly according to the above description.

The electrode assembly may not include a separate separator or insulating sheet surrounding the anode, the cathode, and the separator.

The side surface of the electrode assembly may be in an open shape.

The separator of the electrode assembly may be larger than the positive electrode and the negative electrode.

The secondary battery manufacturing method according to the present invention may include transferring the electrode assembly manufactured according to the electrode assembly manufacturing method according to the above description according to the adsorption method.

The electrode assembly may be transported by pick and place equipment.

The electrode assembly may be transported and accommodated in a pouch-type case.

In the present invention, one or two or more non-conflicting components among the above components may be selected and combined.

In the electrode assembly manufacturing method of the present invention, a wet separator is disposed at the uppermost and lowermost ends of the electrode assembly to prevent damage to the separator that may occur during direction change and transport of the electrode assembly.

In addition, since the electrode assembly is not wrapped with a separate separator or a separator film, a secondary battery having high electrolyte impregnation property can be formed, and the performance and capacity of the secondary battery can be increased.

By disposing the biaxially-stretched separator on the outermost side, damage due to external impact is less, and since multiple separators are not used, the density of the electrode assembly is also improved.

In addition, it is possible to obtain a secondary battery with a low possibility of damage to the outermost part by arranging a wet separator in the outermost part while having economic feasibility by using a dry separator in the central part.

In addition, a method for preventing damage to the separator when moving the electrode assembly while driving is provided, so that a secondary battery can be manufactured quickly and efficiently.

1 is a schematic diagram of an electrode assembly according to the prior art.
2 is a schematic diagram of a method for manufacturing an electrode assembly according to a first embodiment of the present invention.
3 is a schematic diagram of a method for manufacturing an electrode assembly according to a second embodiment of the present invention.

Hereinafter, embodiments in which those of ordinary skill in the art to which the present invention pertains can easily practice the present invention will be described in detail. However, when it is determined that a detailed description of a related well-known function or configuration may unnecessarily obscure the gist of the present invention in describing the operating principle of the preferred embodiment of the present invention in detail, the detailed description thereof will be omitted.

Throughout the specification, when a part is said to be connected to another part, it includes not only a case in which it is directly connected, but also a case in which it is indirectly connected with another element interposed therebetween. In addition, the inclusion of a certain component does not exclude other components unless otherwise stated, but means that other components may be further included.

The separator referred to in the present invention includes all separators having a coating layer added to one or both sides in addition to a porous substrate to which a coating layer is not added.

Hereinafter, the present invention will be described in more detail.

anode

The positive electrode according to the present invention may be manufactured by, for example, applying a positive electrode mixture in which a positive electrode active material composed of positive electrode active material particles, a conductive material and a binder are mixed on a positive electrode current collector, and, if necessary, a filler in the positive electrode mixture can be further added.

The positive electrode current collector is generally manufactured to have a thickness of 3 μm to 500 μm, and is not particularly limited as long as it has high conductivity without causing chemical change in the battery, for example, stainless steel, aluminum, nickel, Titanium, and one selected from a surface treatment of carbon, nickel, titanium, or silver on the surface of aluminum or stainless steel may be used, and specifically aluminum may be used. The current collector may increase the adhesion of the positive electrode active material by forming fine irregularities on the surface thereof, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam body, and a nonwoven body are possible.

The positive active material may include, in addition to the positive active material particles, _{a layered compound such as lithium nickel oxide (LiNiO 2} ) or a compound substituted with one or more transition metals; lithium manganese oxides such as Formula Li _1+x Mn _2-x O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , and LiMnO _{2 ;} lithium copper oxide (Li ₂ CuO ₂ ); vanadium oxides such as LiV ₃ O ₈ , LiV ₃ O ₄ , V ₂ O ₅ , and Cu ₂ V ₂ O _{7 ;} Ni site-type lithium nickel oxide represented by the formula LiNi _1-x M _x O ₂ (wherein M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3); Formula LiMn _2-x M _x O ₂ (where M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li ₂ Mn ₃ MO ₈ (where M = Fe, Co, lithium manganese composite oxide represented by Ni, Cu or Zn; _{LiMn 2} O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; disulfide compounds; Fe ₂ (MoO ₄ ) ₃ It may be configured, and the like, but is not limited thereto.

The conductive material is typically added in an amount of 0.1 wt% to 30 wt% based on the total weight of the mixture including the positive electrode active material. Such a conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery. For example, graphite such as natural graphite or artificial graphite; carbon black, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskeys such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; A conductive material such as a polyphenylene derivative may be used.

The binder included in the positive electrode is a component that assists in bonding between the active material and the conductive material and bonding to the current collector, and is usually added in an amount of 0.1 wt% to 30 wt% based on the total weight of the mixture including the cathode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, and various copolymers.

cathode

The negative electrode according to the present invention is manufactured by coating and drying the negative electrode active material on the negative electrode current collector, and if necessary, the above-described components may be optionally further included.

The negative electrode current collector is generally made to have a thickness of 3 μm to 500 μm. Such a negative current collector is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface. Carbon, nickel, titanium, a surface treated with silver, etc., an aluminum-cadmium alloy, etc. may be used. In addition, like the positive electrode current collector, the bonding force of the negative electrode active material may be strengthened by forming fine irregularities on the surface, and may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a non-woven body.

Examples of the negative electrode active material include carbon such as non-graphitizable carbon and graphitic carbon; Li _x Fe ₂ O ₃ (0≤x≤1), Li _x WO ₂ (0≤x≤1), Sn _x Me _1-x Me' _y O _z (Me: Mn, Fe, Pb, Ge; Me' : metal composite oxides such as Al, B, P, Si, elements of Groups 1, 2, and 3 of the periodic table, halogen; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8); lithium metal; lithium alloy; silicon-based alloys; tin-based alloys; SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ , and metal oxides such as _{Bi 2} O _{5 ;} conductive polymers such as polyacetylene; A Li-Co-Ni-based material or the like can be used.

separator

The separator according to the present invention is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used.

The porous substrate can be used without any particular limitation as long as it can be used as a separator material for secondary batteries among porous membranes with high resistance to electrolyte and fine pores. The pore diameter of the porous substrate is generally 0.01 μm to 10 μm, and the thickness is generally 5 μm to 300 μm. Examples of the porous substrate include olefin-based polymers such as chemical-resistant and hydrophobic polypropylene; A sheet or nonwoven fabric made of glass fiber or polyethylene is used. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as a separator.

The separator according to the present invention may include a coating layer including an inorganic material formed on at least one surface of the porous substrate.

The inorganic material used in the coating layer functions to improve the thermal and mechanical strength of the separator. The type of the inorganic material is not particularly limited as long as the thickness of the coating layer is uniformly formed and oxidation and/or reduction reactions do not occur within the operating voltage range of the applied secondary battery. When inorganic particles having ion transport ability are used, ion conductivity in the electrochemical device can be increased to improve battery performance. When inorganic particles having a high dielectric constant are used as the inorganic particles, the ionic conductivity of the electrolyte may be improved by contributing to an increase in the degree of dissociation of an electrolyte salt, such as a lithium salt, in a liquid electrolyte.

The thickness of the coating layer may be 0.1 μm to 30 μm. The porosity of the coating layer may be in the range of 10% to 90%, preferably 30% to 70%. The particle size of the inorganic material is not particularly limited, but considering the purpose of forming a coating layer having a uniform thickness and having an appropriate porosity, D ₅₀ may be in the range of 20 nm to 10 μm, specifically, 100 nm to 2 μm.

The content of the inorganic material may be 50 parts by weight to 95 parts by weight, preferably 60 parts by weight to 95 parts by weight, based on 100 parts by weight of the total solid content of the coating layer. When the content of the inorganic material is less than 50 parts by weight based on 100 parts by weight of the total solid content of the coating layer, the amount of the binder is excessively large, so that the void space formed between the inorganic particles is reduced. For this reason, the pore size and porosity of the coating layer may be reduced, and thus the performance of the battery may be deteriorated. In addition, when the content of the inorganic material exceeds 95 parts by weight based on 100 parts by weight of the total solid content of the coating layer, the content of the binder is too small, so that the adhesion between the inorganic materials is weakened, and the mechanical properties of the separator itself may be reduced.

The coating layer may further include a binder. The binder serves to stably fix the inorganic material to the surface of the porous substrate, for example, the binder is polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride- Trichloroethylene (polyvinylidene fluoride-trichlorethylene), polymethylmethacrylate (polymethylmethacrylate), polybutylacrylate (polybutylacrylate), polyacrylonitrile (polyacrylonitrile), polyvinylpyrrolidone (polyvinylpyrrolidone), polyvinylacetate (polyvinylacetate) , polyethylene-co-vinylacetate, polyethyleneoxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate ( cellulose acetate propionate), cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan and carboxymethylcellulose (carboxylmethylcellulose) may be any one selected from the group consisting of or a mixture of two or more thereof.

Separator manufacturing method

The separation membrane according to the present invention is divided into a dry separation membrane and a wet separation membrane according to a formation method.

In the case of dry separation membrane, 1) melts porous substrate components such as polypropylene to form a primary film, 2) forms a lamellar structure film with a mixed structure of amorphous/crystalline structure called lamellar structure by stretching and heat setting the formed primary film a little, 3) uniaxially stretching the lamellar structure film to form pores to form a porous substrate.

In the dry separation membrane, pores are regularly formed in the vertical direction of the membrane, and the straightness of the pores is high, so that lithium ions can move easily and the electrical properties are excellent. In addition, the thermal stability is higher than that of the wet membrane.

In the case of a wet separator, 1) a polymer resin and wax are mixed, melted, and then extruded to form a film, 2) the formed film is biaxially stretched to form pores, and 3) wax is removed to form a porous substrate. to form

In the case of the wet separator, the pores are irregular, so the electrical properties are inferior to that of the dry separator, and the thermal stability is poor, but the strength is superior to that of the dry separator.

The above characteristics can be seen through the characteristics of dry and wet separators specified in 『Separator for Lithium Ion Battery Using Dry Stretching Process to Increase Economical and Productivity』 provided by the Technology Evaluation Information Distribution System. Table 1 below shows the characteristics of the dry separation membrane and the wet separation membrane.

The separator according to the present invention may form a coating layer on one or both surfaces of the porous substrate formed by the above method. The coating layer may be formed by applying a coating solution to one or both surfaces of the porous substrate, or by applying a slurry containing a coating layer forming material to one or both surfaces of the porous substrate.

A method of applying the coating solution or slurry to the porous substrate may use a conventional method widely known in the art, for example, dip coating, die coating, roll coating, comma (commna). ) coating or a mixture of these methods can be used.

The application of the coating solution or slurry may be performed one or more times, and when performed two or more times, particles having different sizes or materials having different distributions may be used.

After application as described above, the porous substrate may be dried. For drying the porous substrate, an oven or a heating chamber may be used in a temperature range in consideration of the medium atmospheric pressure of the solvent, and a method of leaving the solvent to volatilize by leaving it at room temperature is also possible. At this time, the temperature range may consider a temperature condition of 25 ° C. to 100 ° C. and a relative humidity of 40% or more.

Non-limiting examples of the solvent that can be used when preparing the slurry include aromatic hydrocarbon solvents, ester solvents, ketone solvents, alcohol solvents, halogen solvents or aqueous solvents, and aprotic polar organic solvents selected from the group consisting of solvents can be mentioned. Examples of the aromatic hydrocarbon-based solvent include benzene, toluene, xylene, mesitylene, ethylbenzene, diethylbenzene, propylbenzene, chlorobenzene, o-dichlorobenzene or t-butylbenzene. Examples of the ester solvent include ethyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate. Examples of the ketone solvent include acetone and cyclohexanone. Examples of the alcohol-based solvent include ethanol, methanol, and examples of the halogen-based solvent include methylene chloride, chloroform, bromoform or carbon tetrachloride. Examples of the aprotic polar organic solvent include dimethylformaldehyde (DMF), dimethylsulfoxide (DMSO), N-methylpyrrolidone (NMP), and N,N-dimethylacetamide (DMAc). These may be used alone, or two or more may be mixed and used. Preferably, acetone, ethanol, NMP (N-Methyl-2-pyrrolidone) may be used, and more preferably NMP (N-Methyl-2-pyrrolidone) may be used.

The content of the solvent is preferably 500 to 1000 parts by weight of the solvent based on 100 parts by weight of the inorganic material. When the solvent is included in less than 500 parts by weight, it is difficult to properly disperse the solid content, and when it exceeds 1000 parts by weight, it is uneconomical to use an excess of the solvent. However, this may vary depending on the type of inorganic material.

In addition, a dispersing agent may be further included in the preparation of the slurry.

As the dispersant, any one can be used as long as it allows the inorganic material to be properly dispersed in the solvent, but tertiary amines; ether; thiol; an ester having a functional group having 3 or more carbon atoms bonded to a carbon atom of the ester bond and a functional group having 4 or more carbon atoms bonded to an oxygen atom of the ester bond; and at least one selected from the group consisting of esters having a benzene ring bonded to a carbon atom of an ester bond, and other low molecular weight compounds and the like. As for carbon number of the said ether compound, 10 or less are preferable. However, it is not limited thereto.

The dispersant may be included in an amount of 2 to 20 parts by weight based on 100 parts by weight of the inorganic material. This is because, when the dispersant is added in too little amount, the dispersing power may be low, and when the dispersing agent is added in a large amount, the dispersing power improvement effect is not large and may affect the characteristics of the battery. However, this may vary depending on the type of dispersant.

The type of the binder that can be used in preparing the slurry is not limited as long as it is inert to the battery. Examples of the binder include nitrile butadiene rubber, polyamide-imide (PAI), polyimide (PI), polyamide (PA), polyamic acid, polyethylene oxide (PEO) , polystyrene (PS), PEP-MNB (poly(ethylene-co-propyleneco-5-methylene-2-norbornene)), PVDF (polyvinylidene fluoride), PVDF-HFP (poly(vinylidene fluoride-co-hexafluoropropylene)) , PS-NBR (polystyrene nitrile-butadiene rubber), PMMA-NBR (poly(methacrylate) nitrile-butadiene rubber), epoxy resins, cyano resins, and a compound selected from the group consisting of mixtures thereof. The content of the binder is preferably 10 to 50 parts by weight based on 100 parts by weight of the flame retardant or inorganic material.

electrolyte

The electrolyte used in the secondary battery according to the present invention is not limited as long as it is an electrolyte that can be used in a battery in general. As an example of the electrolytic solution as described above, a lithium salt-containing non-aqueous electrolytic solution is exemplified.

The non-aqueous electrolyte solution containing lithium salt consists of a non-aqueous electrolyte solution and a lithium salt. As the non-aqueous electrolyte, a non-aqueous organic solvent, an organic solid electrolyte, an inorganic solid electrolyte, and the like are used, but are not limited thereto.

Examples of the non-aqueous organic solvent include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma -Butyl lactone, 1,2-dimethoxy ethane, tetrahydroxy franc, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane , acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbo An aprotic organic solvent such as a nate derivative, a tetrahydrofuran derivative, ether, methyl propionate, or ethyl propionate can be used.

Examples of the organic solid electrolyte include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphoric acid ester polymers, poly agitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, ions A polymer containing a sexually dissociating group or the like can be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides, sulfates, etc. of Li such as Li ₄ SiO ₄ -LiI-LiOH, Li ₃ PO ₄ -Li ₂ S-SiS _{2 and the like may be used.}

The lithium salt is a material easily soluble in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF _{6 , LiAlCl 4} , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, (CF ₃ SO ₂ ) ₂ NLi, lithium chloroborane, lithium lower aliphatic carboxylate, lithium 4-phenyl borate, imide, etc. may be used. .

In addition, for the purpose of improving charge/discharge characteristics, flame retardancy, etc. in the nonaqueous electrolyte, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphate triamide, Nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, aluminum trichloride, etc. may be added. have. In some cases, in order to impart incombustibility, a halogen-containing solvent such as carbon tetrachloride and ethylene trifluoride may be further included, and carbon dioxide gas may be further included to improve high-temperature storage characteristics, and FEC (Fluoro-Ethylene) Carbonate), PRS (Propene Sultone), etc. may be further included.

Electrode assembly manufacturing method

2 shows a schematic diagram of a method for manufacturing an electrode assembly according to a first embodiment of the present invention. As can be seen in FIG. 2 , in the method for manufacturing an electrode assembly according to the present invention, (S1) the first separator 120, the first electrode 110, the second separator 121, the second electrode 130, and the third a first unit cell 100 including a separator 122 and a first electrode 110 ; and a second unit cell 200 including a fourth separator 221 , a second electrode 230 , and a fifth separator 220; forming each; (S2) stacking the second unit cell 200 on the outermost first electrode 110 of the first unit cell 100 so that the fourth separator 221 faces to form an electrode assembly; includes The first separator may be a wet separator, and the second separator, the third separator, and the fourth separator may be a dry separator. In this case, the fifth separation membrane may also be a wet separation membrane.

In this case, in addition to the above structure, the first unit cell includes a first separator, a first electrode, a first separator, a first electrode, and a second separator, a first separator, a first electrode, and a second separator. It may have a structure including two separators and a second electrode, or a structure including a first separator, a first electrode, a second separator, a second electrode, and a third separator. Correspondingly, the number of separators or the number of electrodes of the second unit cell may increase. However, when the first unit cell and the second unit cell are stacked, a separator should be interposed between each electrode and at the outermost part of the electrode assembly, and the outermost separator of the electrode assembly should be a separator manufactured by a wet method. do. In addition, it is preferable that the number of the first electrode and the second electrode is the same.

After laminating electrodes and separators, the first unit cell and the second unit cell are heated and pressed by a roll lamination process to adhere. The bonded unit cells may then be cut to a desired size by a cutter to form an electrode assembly.

In the present invention, the electrode assembly may be formed by stacking the first unit cell and the second unit cell formed in step (S1). At this time, the first unit cell and the second unit cell are stacked such that the wet separator is disposed at the outermost, that is, the uppermost and lowermost ends, with the separator interposed between the electrodes.

In the step (S2), the electrode assembly according to the present invention is manufactured in a stack-type or lamination stack-type structure. The electrode assembly according to the present invention may be laminated and then adhered by a lamination process.

It is preferable that the first separator of the first unit cell used in the method for manufacturing an electrode assembly of the present invention is a wet separator, and the second to fourth separators are dry.

In the case of the wet separation membrane, as mentioned above, it is manufactured by biaxial stretching, and thus the strength of the separation membrane is excellent. However, wet separation membranes have disadvantages in that ion conductivity and thermal stability are inferior compared to dry separation membranes. In order to compensate for this, a dry separator is used for the second to fourth separators to improve the capacity and safety of the battery.

In this case, a case of using only one separator in contact with the pick-and-place may be considered, but it is preferable that the fifth separator as well as the first separator be wet so that it can be moved using both surfaces of the electrode assembly.

3 is a schematic diagram of a method for manufacturing an electrode assembly according to a second embodiment of the present invention. 3 , the electrode assembly manufacturing method according to the present invention may stack a plurality of unit cells. For example, between the steps (S1) and (S2), (S1-1) the sixth separator 320, the second electrode 330, the seventh separator 321, and the first electrode 310 forming a third unit cell 300 composed of; (S1-2) stacking one or more of the third unit cells 300 on the outermost first electrode 110 of the first unit cell 100 so that the sixth separator 320 faces them; further and an electrode assembly manufacturing method comprising.

One or more of the third unit cells may be stacked between the first unit cell and the second unit cell. To this end, after laminating the third unit cell 300 , a fourth separator 221 of the second unit cell 200 is laminated on the first electrode 310 of the third unit cell 300 , An electrode assembly may be formed.

In this case, it is preferable that the 6th and 7th separation membranes, which are the separation membranes of the third unit cell, are dry separation membranes.

The present invention may be an electrode assembly manufactured by the manufacturing method as described above.

The electrode assembly may be an electrode assembly that does not include a separate separator or insulating sheet surrounding the positive electrode, the negative electrode, and the separator. In the present invention, there is an open space in which the electrolyte can be impregnated on the side surface of the stacked electrode assembly as shown in FIGS. 2 and 3 .

In addition, in the electrode assembly according to the present invention, each adhesive force between the first and second electrodes and each separator may be 20 gf/cm or more in order to prevent damage to the electrode assembly during movement. To this end, the adhesive force between each electrode and the separator may be improved by changing the type of binder used between each electrode and the separator, or by disposing an anode active material or a cathode active material on a coating layer of the separator.

The electrode assembly according to the present invention may be an electrode assembly for a large-capacity battery in which the weight of the electrode assembly is 500 g or more. In the case of moving the electrode assembly using pick and place, the heavier the electrode assembly, the higher the possibility of damage to the outermost separator. Therefore, the effect is maximized when an electrode assembly having a heavy weight and a large capacity is formed.

The positive electrode and the negative electrode used in the electrode assembly of the present invention are smaller in size than the separator. This is to prevent an electrical short circuit due to thermal contraction of the separator.

The secondary battery manufacturing method according to the present invention includes the step of moving the electrode assembly in another direction or moving the electrode assembly to another location while driving. In order to improve the manufacturing speed of the electrode assembly or the secondary battery, it is important to move the electrode assembly to a desired place or change the direction while driving using a conveyor belt. To this end, the secondary battery manufacturing method according to the present invention includes moving the electrode assembly manufactured according to the above-mentioned electrode assembly manufacturing method according to the adsorption method. The adsorption method is performed by pick-and-place equipment. In addition to the pick-and-place equipment, it may include any equipment that moves the electrode assembly by an adsorption method. In addition, the secondary battery manufacturing method according to the present invention includes the step of moving the electrode assembly in another direction or moving the electrode assembly to another place while driving.

In addition, the electrode assembly according to the present invention may be transported and accommodated in a pouch-type case. Such a pouch-type case is not limited in its material and form, as long as it is a form used in an existing secondary battery.

The present invention also provides a battery pack including the secondary battery and a device including the battery pack, and since the battery pack and device as described above are known in the art, a detailed description thereof will be omitted herein. do.

The device is, for example, a notebook computer, a netbook, a tablet PC, a mobile phone, an MP3, a wearable electronic device, a power tool, an electric vehicle (EV), a hybrid electric vehicle (HEV) , a Plug-in Hybrid Electric Vehicle (PHEV), an electric bicycle (E-bike), an electric scooter (E-scooter), an electric golf cart, or a system for power storage. However, of course, it is not limited only to these.

Those of ordinary skill in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above content.

10: electrode assembly
11: positive electrode
12: separator
13: cathode
14: separation film
100: first unit cell
110, 310: first electrode
120: first separator
121: second separator
122: third separator
130, 230, 330: second electrode
200: second unit cell
220: fifth separator
221: fourth separator
300: third unit cell
320: sixth separator
321: 7th separation membrane

Claims (14)

(S1) a first unit cell comprising a first separator, a first electrode, a second separator, a second electrode, a third separator, and a first electrode; and a second unit cell including a fourth separator, a second electrode, and a fifth separator; forming each;
(S2) stacking the second unit cell on the outermost first electrode of the first unit cell so that the fourth separator faces to form an electrode assembly;
The first separator is a wet separator, and the second separator, the third separator, and the fourth separator are dry separators. According to claim 1,
The fifth separator is a wet separator, an electrode assembly manufacturing method. According to claim 1,
Between the step (S1) and the step (S2),
(S1-1) forming a third unit cell composed of a sixth separator, a second electrode, a seventh separator, and a first electrode;
(S1-2) stacking one or more of the third unit cells on the outermost first electrode of the first unit cell so that the sixth separator faces each other; 4. The method of claim 3,
The third unit cell is an electrode assembly manufacturing method comprising one or more present between the first unit cell and the second unit cell. 4. The method of claim 3,
The sixth separator and the seventh separator are dry separators. According to claim 1,
In the step (S2), the electrode assembly is a stack type or a lamination/stack type structure of an electrode assembly manufacturing method. According to claim 1,
The wet separator is produced by biaxial stretching, and the dry separator is produced by uniaxial stretching. An electrode assembly manufactured according to the method for manufacturing an electrode assembly according to any one of claims 1 to 7. 9. The method of claim 8,
The electrode assembly does not include a separate separator or insulating sheet surrounding the positive electrode, the negative electrode, and the separator. 9. The method of claim 8,
The electrode assembly comprising the side of the electrode assembly is in an open shape. 9. The method of claim 8,
and the separator of the electrode assembly is larger than the positive electrode and the negative electrode. A method for manufacturing a secondary battery comprising: transferring an electrode assembly manufactured according to the method for manufacturing an electrode assembly according to any one of claims 1 to 7 according to an adsorption method. 13. The method of claim 12,
The electrode assembly is a secondary battery manufacturing method that is transferred by a pick and place equipment. 13. The method of claim 12,
The electrode assembly is a secondary battery manufacturing method that is transported and accommodated in a pouch-type case.

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