Method for manufacturing an electrode laminate

Abstract

The method for manufacturing an electrode laminate according to the present invention includes a step of preparing an electrode, a step of coating an electrolytic solution on the electrode, a step of disposing an oxygen barrier member on the coated electrolytic solution, and a step of curing the electrolytic solution impregnated inside the electrode and the electrolytic solution coated on the surface of the electrode.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0109521, filed on August 30, 2022, and all the contents disclosed in the document of the Korean Patent Application are incorporated herein by reference in their entirety.

[0002] The present invention relates to a method for manufacturing an electrode laminate.

Background Art

[0003] As technology development and demand related to electric vehicles and energy storage systems (ESS) increase, the demand for batteries as an energy source thereof is rapidly increasing. Accordingly, various studies on batteries that can meet various requirements are being conducted in a diverse manner. In particular, research on lithium secondary batteries having a high energy density and excellent life and cycle characteristics as a power source for such devices is actively underway.

[0004] Generally, a lithium secondary battery includes a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, an electrolyte, and the like. Conventionally, as an electrolyte for a lithium secondary battery, a liquid electrolyte in which a lithium salt is dissolved in a non-aqueous organic solvent has been mainly used. However, when using a liquid electrolyte, there is a high possibility that the electrode material deteriorates and the organic solvent volatilizes, and there are concerns about combustion, explosion due to an increase in the ambient temperature and the temperature of the battery itself, and liquid leakage, resulting in low safety.

[0005] In recent years, in order to overcome the safety problems of liquid electrolytes, various studies on various materials or types of solid electrolytes are actively underway. Among them, a gel electrolyte has advantages not only in excellent stability and processability but also in excellent interfacial stability between the electrode and the electrolyte due to its inherent adhesive force in a gel state.

[0006] On the one hand, the gel electrolyte can be manufactured by gelling (crosslinking) a composition obtained by mixing a lithium salt, a solvent, a polymerizable monomer, and an initiator at an appropriate temperature and for an appropriate time. At this time, when the electrolyte is gelled in an oxygen-containing environment, the gel electrolyte is not completely cured. As a result, there are problems such that the gel electrolyte volatilizes during the cell manufacturing process or comes into contact with other electrodes and detaches. To solve this problem, when the electrolyte is gelled in a space where an oxygen-free environment is realized (for example, a glove box), there is a problem that it is difficult to manufacture a large-area electrode laminate due to the limitation of the size of the space.

[0007] Thus, in a situation where technological development is required for a method capable of manufacturing a large-area electrode laminate by completely curing a gel electrolyte even in an oxygen-containing environment.

Summary of the Invention

Problems to be Solved by the Invention

[0008] The present invention is for solving the above problems, and an object thereof is to provide a method capable of completely curing a gel electrolyte even in an oxygen-containing environment by blocking contact between the gel electrolyte and oxygen using an oxygen-blocking member.

Means for Solving the Problems

[0009] According to one embodiment of the present invention, there is provided a method for manufacturing an electrode laminate including steps of preparing an electrode, coating an electrolyte solution on the electrode, disposing an oxygen-blocking member on the coated electrolyte solution, and curing the electrolyte solution impregnated inside the electrode and the electrolyte solution coated on the surface of the electrode.

[0010] According to the method for manufacturing an electrode laminate of the present invention, an electrolyte layer may be formed on the electrode by curing the electrolyte solution coated on the surface of the electrode.

[0011] The oxygen barrier member may include one or more selected from the group consisting of glass, polypropylene (PP), and high density polyethylene (HDPE).

[0012] The electrolytic solution may contain 5 wt% to 50 wt% of a monomer, 0.01 wt% to 1 wt% of an initiator, and 5 wt% to 30 wt% of a lithium salt.

[0013] The monomer may include one or more selected from the group consisting of ethylene glycol diacrylate, triethylene glycol diacrylate, ethoxylated trimethylolpropane triacrylate (ETPTA), bisphenol A ethoxylated dimethacrylate, acrylic acid, carboxyethyl acrylate, methyl cyanoacrylate, ethyl cyanoacrylate, ethyl cyano ethoxyacrylate, cyano acrylic acid, hydroxyethyl methacrylate, and hydroxypropyl acrylate.

[0014] The initiator may include at least one selected from the group consisting of HMPP (2-hydroxy-2-methylpropiophenone), 1-hydroxy-cyclohexylphenyl-ketone, benzophenone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester of oxy-phenylacetic acid, 2-[2-hydroxyethoxy]-ethyl ester of oxy-phenyl-acetic acid, α-dimethoxy-α-phenylacetophenone, 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone, diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(η5-2,4-cyclopentadien-1-yl), bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl]titanium, 4-isobutylphenyl-4'-methylphenyliodonium, hexafluorophosphate, and methylbenzoylformate.

[0015] According to the method for manufacturing the electrode laminate of the present invention, the electrolyte layer may be formed by photocuring or thermocuring the electrolytic solution.

[0016] According to the method for manufacturing the electrode laminate of the present invention, the content of the solid component in the electrolytic solution may be 10% to 60%.

[0017] According to the method for manufacturing the electrode laminate of the present invention, the viscosity of the electrolytic solution at 25°C may be 30 cP or less.

[0018] According to the method for manufacturing the electrode laminate of the present invention, the thickness of the electrolyte layer may be 10 μm to 200 μm.

[0019] According to the method for manufacturing the electrode laminate of the present invention, the thickness of the electrode may be 100 μm or less.

Advantages of the Invention

[0020] According to the present invention, by curing the electrolytic solution in a state where the contact between the electrolytic solution and oxygen is blocked using an oxygen-blocking member, the gel electrolyte can be completely cured even in an environment with oxygen. As a result, problems such as the volatilization of the gel electrolyte or its detachment due to contact with other electrodes during the cell manufacturing process can be prevented.

[0021] In addition, the electrolytic solution can be cured in a state where it is impregnated to a sufficient depth of the electrode. As a result, even when another liquid electrolytic solution is not injected into the electrode laminate during the manufacture of the lithium secondary battery, the reaction occurs uniformly throughout the electrode, and the capacity, output, and life characteristics of the lithium secondary battery can be improved.

[0022] Furthermore, according to the present invention, since it is not necessary to gel the electrolyte in a space such as a glove box where an oxygen-free environment is realized, there is an advantage that a large-area electrode laminate can be manufactured.

Brief Description of the Drawings

[0023]

Figure 1

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Modes for Carrying Out the Invention

[0024] The advantages and features of the present invention, and the ways to achieve them, will become clear by referring to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and can be realized in various different forms. These embodiments are provided to make the disclosure of the present invention complete and to fully convey the scope of the invention to those with ordinary knowledge in the technical field to which the present invention pertains. The present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals indicate the same components.

[0025] Unless otherwise defined, all terms (including technical and scientific terms) used in this specification can be used in a meaning commonly understood by those with ordinary knowledge in the technical field to which the present invention pertains. Also, terms defined in commonly used dictionaries are not ideally or excessively interpreted unless specifically defined otherwise.

[0026] The terms used in this specification are for explaining the embodiments and not for limiting the present invention. In this specification, the singular form includes the plural form as well unless otherwise specifically mentioned in the text. The "comprises" and / or "comprising" used in the specification do not exclude the presence or addition of one or more other components in addition to the recited components.

[0027] In this specification, when a certain part is said to include a certain component, this means that it can further include other components rather than excluding other components unless otherwise stated to the contrary.

[0028] In this specification, the description of "A and / or B" means A, or B, or A and B.

[0029] In this specification, "%" means weight % unless otherwise explicitly indicated.

[0030] In this specification, the viscosity can be measured using a viscometer. Specifically, it can be measured using a Brookfield viscometer (DV-II+PRO Viscometer, Brookfield) at a temperature of 25°C, a humidity of 50RH%, and a frequency of 30 Hz.

[0031] Hereinafter, the present invention will be described in more detail.

[0032] The method for manufacturing an electrode laminate according to the present invention includes a step of preparing an electrode, a step of coating an electrolyte solution on the electrode, a step of disposing an oxygen-blocking member on the coated electrolyte solution, and a step of curing the electrolyte solution impregnated inside the electrode and the electrolyte solution coated on the surface of the electrode.

[0033] When gelling an electrolyte in an oxygen-containing environment, there are problems that the gel electrolyte is not completely cured, and as a result, the gel electrolyte volatilizes or comes into contact with other electrodes and detaches during the cell manufacturing process. To solve this problem, when gelling an electrolyte in a space where an oxygen-free environment is realized (for example, a glove box), there is a problem that it is difficult to manufacture a large-area electrode laminate due to the limitation of the space size.

[0034] As a result of repeated research to solve such problems, the present inventors have found that by curing the electrolyte solution in a state where the contact between the electrolyte solution and oxygen is blocked using an oxygen-blocking member, the gel electrolyte can be completely cured even in an oxygen-containing environment, and thus the present invention has been completed.

[0035] Hereinafter, each step of the method for manufacturing an electrode laminate according to the present invention will be described in more detail.

[0036] <Method for Manufacturing Electrode Laminate> (1) Step of preparing an electrode The method for manufacturing an electrode laminate according to the present invention starts with a step of preparing an electrode for a lithium secondary battery. In this case, the electrode may be a positive electrode or a negative electrode.

[0037] The electrode includes a current collector and an electrode active material layer. In this case, the electrode active material layer may be formed on the current collector.

[0038] The current collector is not particularly limited as long as it does not cause a chemical change in the battery and has conductivity. For example, as the current collector, copper, stainless steel, aluminum, nickel, titanium, fired carbon, or a material obtained by surface treatment of the surface of aluminum or stainless steel with carbon, nickel, titanium, silver, etc. may be used.

[0039] Next, the electrode active material layer may be a positive electrode active material layer containing a positive electrode active material or a negative electrode active material layer containing a negative electrode active material.

[0040] As the positive electrode active material, known positive electrode active materials in the art can be used without limitation. For example, lithium cobalt-based oxides, lithium nickel-based oxides, lithium manganese-based oxides, lithium iron phosphate, lithium nickel manganese cobalt-based oxides, or combinations thereof can be used. Specifically, as the positive electrode active material, LiCoO2, LiNiO2, LiMn2O4, LiCoPO4, LiFePO4, and LiNi a Mn b Co c O2 (where 0 < a, b, c < 1) etc. can be used, but it is not limited thereto.

[0041] As the negative electrode active material, natural graphite, artificial graphite, carbonaceous materials; lithium-containing titanium composite oxides (LTO), Si, Sn, Li, Zn, Mg, Cd, Ce, Ni, or metals (Me) such as Fe; alloys composed of the metals (Me); oxides (MeO x ); and one or more negative electrode active materials selected from the group consisting of composites of the metals (Me) and carbon can be mentioned.

[0042] On the one hand, the electrode active material layer may further contain a conductive material and a binder in addition to active materials such as a positive electrode active material and a negative electrode active material.

[0043] The conductive material is a component for further improving the conductivity of the active material, and such a conductive material is not particularly limited as long as it does not cause a chemical change in the battery and has conductivity. For example, as the conductive material, graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, nickel powder; conductive whiskers such as zinc oxide, potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives may be used. Specific examples of commercially available conductive materials include those of the acetylene black type such as Chevron Chemical Company, Denka Singapore Private Limited, Gulf Oil Company, etc., Ketjenblack, EC series (manufactured by Armak Company), Vulcan XC-72 (manufactured by Cabot Company), and Super P (manufactured by Timcal).

[0044] The binder is a component that helps bind the active material and the conductive material, etc., and the binding to the current collector. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, various copolymers thereof, and the like.

[0045] The thickness of the electrode according to the present invention may be 100 μm or less, specifically 20 μm to 100 μm, and more specifically 50 μm to 100 μm. When the thickness of the electrode satisfies the above numerical range, the electrolyte described below can be cured in a state where it is impregnated to a sufficient depth of the electrode. As a result, even when another liquid electrolyte is not injected into the electrode laminate during the manufacture of the lithium secondary battery, the reaction occurs uniformly throughout the electrode, so that the capacity, output, and life characteristics of the lithium secondary battery can be improved.

[0046] (2) Step of coating the electrolyte on the electrode Next, the step of coating the electrolyte on the electrode will be described.

[0047] The electrolyte according to the present invention may contain a monomer, an initiator, a lithium salt, and a solvent.

[0048] The monomer is a substance that can form a gel electrolyte by a polymerization reaction.

[0049] For example, the monomer may be, but is not limited to, ethylene glycol diacrylate, triethylene glycol diacrylate, ethoxylated trimethylolpropane triacrylate (ETPTA), bisphenol A ethoxylated dimethacrylate, acrylic acid, carboxyethyl acrylate, methyl cyanoacrylate, ethyl cyanoacrylate, ethyl cyano ethoxyacrylate, cyano acrylic acid, hydroxyethyl methacrylate, hydroxypropyl acrylate, derivatives thereof, or combinations thereof.

[0050] The monomer may be contained in an amount of 5 to 50 parts by weight, specifically 5 to 30 parts by weight, more specifically 5 to 20 parts by weight, based on 100 parts by weight of the electrolyte solution. When the monomer is contained within the above content range, the cross-linking reaction between the monomers can be sufficiently carried out, and an electrolyte layer having a specific thickness range can be manufactured.

[0051] The initiator is a substance that forms active radicals and causes the polymerization reaction of the monomer. Specifically, the initiator can initiate the free radical polymerization reaction of the monomer by being decomposed by light such as UV at room temperature (5°C to 30°C) or by being decomposed by heat at 30°C to 100°C to form radicals.

[0052] The initiator may include at least one or more selected from the group consisting of a photoinitiator and a thermal initiator.

[0053] When the initiator is a photoinitiator, the initiator may include at least one or more selected from the group consisting of HMPP (2-hydroxy-2-methylpropiophenone), 1-hydroxy-cyclohexylphenyl-ketone, benzophenone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester of oxy-phenylacetic acid, 2-[2-hydroxyethoxy]-ethyl ester of oxy-phenyl-acetic acid, α-dimethoxy-α-phenylacetophenone, 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone, diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(η5-2,4-cyclopentadien-1-yl), bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl]titanium, 4-isobutylphenyl-4'-methylphenyliodonium, hexafluorophosphate, and methylbenzoylformate.

[0054] When the initiator is a thermosetting agent, the initiator may include at least one selected from the group consisting of benzoyl peroxide, acetyl peroxide, dilauryl peroxide, di-tert-butyl peroxide, t-butyl peroxy-2-ethyl-hexanoate, cumyl hydroperoxide, hydrogen peroxide, 2,2'-azobis(2-cyanobutane), 2,2'-azobis(methylbutyronitrile), 2,2'-azobis(iso-butyronitrile) (AIBN; 2,2'-Azobis(iso-butyronitrile)), and 2,2'-azobisdimethyl-valeronitrile (AMVN; 2,2'-Azobisdimethyl-Valeronitrile).

[0055] The initiator may be included in an amount of 0.01 to 1 part by weight, specifically 0.05 to 0.5 part by weight, more specifically 0.06 to 0.1 part by weight, based on 100 parts by weight of the electrolyte solution. When the initiator is included within the above content range, the cross-linking reaction between monomers can be made smooth, an electrolyte layer can be formed with a uniform thickness, the polymerization rate can be controlled in the electrolyte solution, and the drawback that unreacted initiator remains and adversely affects the performance of the battery can be prevented.

[0056] The lithium salt is used as a mediator for transmitting ions in a lithium secondary battery.

[0057] The lithium salt is a substance that is easily dissolved in the gel electrolyte. For example, LiCl, LiBr, LiI, LiClO4, LiBF4, LiB 10 Cl 10, LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, (CF3SO2)2NLi, lithium chloroborane, lithium lower aliphatic carboxylate, lithium 4-phenylborate, imide, or a single substance or a mixture of two or more selected from the group consisting of these, but not limited thereto.

[0058] The lithium salt may be contained in an amount of 5 to 30 parts by weight, specifically 10 to 20 parts by weight, more specifically 10 to 15 parts by weight, based on 100 parts by weight of the electrolytic solution. When the lithium salt is contained within the above content range, the cured electrolytic solution can have sufficient ionic conductivity.

[0059] The solvent is for dissolving the aforementioned monomer, initiator, and lithium salt.

[0060] The solvent is one commonly used in secondary batteries, and for example, ether, ester (acetates, propionates), amide, linear carbonate or cyclic carbonate, nitrile (acetonitrile, SN, etc.) may be used alone or in combination of two or more.

[0061] Among them, typically, a carbonate-based solvent containing a carbonate compound which is a cyclic carbonate, a linear carbonate, or a mixture thereof may be used.

[0062] Specific examples of the cyclic carbonate compound include a single compound selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate, and halides thereof, or a mixture of at least two or more thereof. Specific examples of the linear carbonate compound include a compound selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), and ethyl propyl carbonate (EPC), or a mixture of at least two or more thereof, and the like can be typically used, but are not limited thereto.

[0063] In particular, among the carbonate solvents, propylene carbonate and ethylene carbonate, which are cyclic carbonates, are high-viscosity organic solvents with a high dielectric constant, making it easy to dissociate lithium salts in the electrolyte, so they can be preferably used. When such cyclic carbonates are mixed with a linear carbonate having a low viscosity and a low dielectric constant, such as ethyl methyl carbonate, diethyl carbonate, or dimethyl carbonate, in an appropriate ratio, an electrolyte having a high electrical conductivity can be produced, so it can be more preferably used.

[0064] Among the solvents, as the ester, a single compound selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone, γ-valerolactone, γ-caprolactone, α-valerolactone, and ε-caprolactone, or a mixture of at least two or more thereof may be used, but is not limited thereto.

[0065] The content of the solid component in the electrolyte may be 10% to 60%, specifically 15% to 50%, and more specifically 15% to 35%. When the content of the solid component of the electrolyte satisfies the above numerical range, the electrolyte can have a viscosity at a level that can coat the electrode active material layer. In addition, since the solvent is easily removed during the hardening of the electrolyte, it is possible to prevent the occurrence of side reactions due to the residual solvent and the problem of the mechanical strength of the electrolyte layer decreasing.

[0066] The viscosity of the electrolyte at 25°C may be 30 cP or less, specifically 5 cP to 30 cP, and more specifically 10 cP to 20 cP. When the viscosity of the electrolyte satisfies the above numerical range, the electrolyte can be cured in a state of being impregnated to a sufficient depth of the electrode. As a result, even when another liquid electrolyte is not injected into the electrode laminate during the manufacture of the lithium secondary battery, the reaction occurs uniformly throughout the electrode, so that the capacity, output, and life characteristics of the lithium secondary battery can be improved.

[0067] As the coating method of the electrolyte, a normal coating method may be used. For example, bar coating, spin coating, roll coating, slot die coating, hand coating, spray coating, etc. may be mentioned. Among these, one method may be used alone, or two or more methods may be used in combination.

[0068] (3) Step of disposing an oxygen barrier member on the coated electrolyte Next, an oxygen barrier member is disposed on the electrolyte coated on the electrode. By covering the electrolyte with the oxygen barrier member, the contact between the electrolyte and oxygen can be blocked.

[0069] The oxygen barrier member may be insoluble in the solvent in order to effectively block the contact between the electrolyte and oxygen. Specifically, the oxygen barrier member may be insoluble in an organic solvent.

[0070] For example, the oxygen barrier member may include, but is not limited to, one or more selected from the group consisting of glass, polypropylene (PP), and high density polyethylene (HDPE).

[0071] The thickness of the oxygen barrier member may be from 100 μm to 2000 μm, specifically from 100 μm to 500 μm, and more specifically from 100 μm to 200 μm. When the thickness of the oxygen barrier member satisfies the above numerical range, the contact between the electrolyte and oxygen can be blocked, and the hardening of the electrolyte can be completed.

[0072] (4) A step of curing the electrolyte impregnated inside the electrode and the electrolyte coated on the surface of the electrode Next, the electrolyte impregnated inside the electrode and the electrolyte coated on the surface of the electrode are cured. In this case, by curing the electrolyte coated on the surface of the electrode, an electrolyte layer can be formed on the electrode.

[0073] The curing of the electrolyte may be photo-curing or heat-curing. Specifically, the curing of the electrolyte is such that the monomers contained in the electrolyte are crosslinked by irradiating ultraviolet rays (UV) or applying heat to the electrolyte covered with the oxygen barrier member. By curing the electrolyte in a state where the contact between the electrolyte and oxygen is blocked by the oxygen barrier member, problems such as the evaporation of the electrolyte or the detachment of the electrolyte layer by contact with other electrodes can be prevented.

[0074] The electrolyte layer of the present invention may include a polymer matrix formed by crosslinking a monomer and an initiator, and a lithium salt impregnated in the polymer matrix. At this time, since the electrolyte layer contains a lithium salt, it can have ionic conductivity.

[0075] The degree of curing of the electrolyte layer may be 93% to 100%, specifically 95% to 100%, and more specifically 98% to 100%. When the degree of curing of the electrolyte layer satisfies the above range, the electrolyte layer can be formed with a uniform thickness on the active material layer, and the phenomenon of the electrolyte layer peeling off from the active material layer can be prevented.

[0076] The thickness of the electrolyte layer may be 10 μm to 200 μm, specifically 10 μm to 150 μm, and more specifically 20 μm to 80 μm. When the thickness of the electrolyte layer satisfies the above numerical range, peeling of the electrolyte layer from the active material layer is prevented, passage of cations (Li+), which are ion conductors, is facilitated, and a decrease in performance due to the total volume of the lithium secondary battery can be minimized.

[0077] After the hardening of the electrolytic solution is completed, the oxygen barrier member disposed on the electrolyte layer can be removed.

[0078] <Method for manufacturing a lithium secondary battery> Next, a method for manufacturing a lithium secondary battery according to the present invention will be described.

[0079] The lithium secondary battery according to the present invention includes an electrode assembly.

[0080] According to an embodiment of the present invention, the electrode assembly can be manufactured by arranging an electrode laminate having an electrolyte layer formed thereon and an electrode having no electrolyte layer formed thereon in contact with each other. In this case, the electrode laminate is as described above.

[0081] For example, the electrode assembly of the present invention can be manufactured by arranging a negative electrode, an electrode laminate including an electrolyte layer formed on the negative electrode, and a positive electrode having no electrolyte layer formed thereon in contact with each other. Alternatively, the electrode assembly of the present invention can include a positive electrode, an electrode laminate including an electrolyte layer formed on the positive electrode, and a negative electrode having no electrolyte layer formed thereon. At this time, the electrolyte layer may be disposed between the positive electrode and the negative electrode.

[0082] According to another embodiment of the present invention, the electrode assembly can be manufactured by arranging a plurality of the above-described electrode laminates such that the electrolytes are in contact with each other. By forming the electrode assembly in such a manner, the electrical insulation is improved, and stable charging and discharging of the battery can proceed.

[0083] The lithium secondary battery of the present invention may not include a separator that was disposed between the positive electrode and the negative electrode in a conventional lithium secondary battery. Specifically, by disposing the electrolyte layer included in the electrode laminate of the present invention between the positive electrode and the negative electrode, the role of the conventional separator can be fulfilled.

[0084] Further, the lithium secondary battery of the present invention may not include the liquid electrolyte that was injected during the manufacture of a conventional lithium secondary battery. Specifically, by curing the above-described electrolyte of the present invention in a state where the electrodes are impregnated to a sufficient depth, the role of the conventional liquid electrolyte can be fulfilled.

[0085] The lithium secondary battery of the present invention can be manufactured by placing the above-described electrode assembly in a cylindrical battery case or a rectangular battery case and sealing it. As the battery case, those commonly used in the art may be adopted, and there is no limitation on the outer shape depending on the use of the battery. For example, it may be cylindrical, rectangular, pouch-shaped, or coin-shaped, etc., but is not limited thereto.

[0086] The lithium secondary battery according to one implementation example of the present invention can be used not only as a battery cell for a power source of a small device, but also preferably as a unit battery in a medium- to large-sized battery module including a large number of battery cells. Preferred examples of the medium- to large-sized device include electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and energy storage systems (ESS).

[0087] Hereinafter, the present invention will be described more specifically with reference to specific examples. However, the following examples are merely illustrative for understanding the present invention and are not intended to limit the scope of the present invention. It is obvious to those skilled in the art that various changes and modifications can be made within the scope of the description and the technical idea, and it goes without saying that such variations and modifications belong to the scope of the appended claims.

[0088] Examples and Comparative Examples Example 1 (1) Manufacture of Electrode Laminate As a negative electrode current collector, a copper (Cu) metal thin film with a thickness of 10 μm was prepared, and a 70-μm negative electrode active material layer containing artificial graphite as a negative electrode active material was formed on one surface of the copper metal thin film to manufacture a negative electrode with a total thickness of 80 μm.

[0089] A monomer, an initiator, and a lithium salt were dissolved in a solvent with a volume ratio of ethylene carbonate (EC) to propylene carbonate (PC) of 5:5 at a weight ratio of 3.98:0.04:5.98 to produce an electrolytic solution. At this time, the solid content of the electrolytic solution was 25%, and the viscosity at 25 °C was 15 cP.

[0090] ]> The manufactured electrolytic solution was coated on the active material layer, and the coated electrolytic solution was covered with a polypropylene film. Next, ultraviolet light with a wavelength of 556 nm was irradiated on the polypropylene film for 1 minute to cure the electrolytic solution. After the curing of the electrolytic solution was completed, the polypropylene film was removed, and finally, an electrode laminate with an electrolyte layer formed on the electrode active material layer was manufactured. At this time, the thickness of the electrolyte layer was 40 μm.

[0091] (2) Manufacture of Lithium Secondary Battery As a positive electrode active material, a 60-μm positive electrode containing Li(Ni 0.8 Mn 0.1 Co 0.1 )O₂ was prepared.

[0092] The electrolyte layer of the manufactured electrode laminate was placed in contact with the positive electrode to manufacture an electrode assembly.

[0093] A lithium secondary battery was manufactured by housing the electrode assembly in a battery case and then sealing it.

[0094] Example 2 An electrode laminate was manufactured in the same manner as in Example 1, except that a glass plate was used instead of the polypropylene film. At this time, the thickness of the electrolyte layer was 30 μm.

[0095] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above electrode laminate was used.

[0096] Comparative Example 1 An electrode laminate was manufactured in the same manner as in Example 1, except that the electrolyte was cured without being covered with a polypropylene film. At this time, the thickness of the electrolyte layer was 10 μm.

[0097] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above electrode laminate was used.

[0098] Experimental Example 1 - Evaluation of the Coating Property of the Electrolyte Layer The surfaces of the electrode laminates manufactured in Example 1 to Example 2 and Comparative Example 1 were photographed and shown in FIGS. 1 to 3.

[0099] Specifically, FIG. 1 is a photograph of the surface of the electrode laminate manufactured in Example 1, FIG. 2 is a photograph of the surface of the electrode laminate manufactured in Example 2, and FIG. 3 is a photograph of the surface of the electrode laminate manufactured in Comparative Example 1.

[0100] In addition, the surface of the electrode laminate was visually observed, and the presence or absence of detachment or lifting of the electrolyte layer from the active material layer was shown as in Table 1 below. X: No detachment or lifting O: There is detachment or lifting

[0101] [Table 1]

[0102] As shown in Table 1 and FIGS. 1 to 3, in Comparative Example 1 where the oxygen barrier member was not used during the curing of the electrolyte, unlike Example 1 and Example 2 where the oxygen barrier member was used during the curing of the electrolyte, it was confirmed that the electrolyte layer contained in the electrode laminate detached from or floated up from the active material layer.

[0103] Experimental Example 2 - Evaluation of Whether a Lithium Secondary Battery Operates To evaluate whether the lithium secondary batteries manufactured in Example 1 to Example 2 and Comparative Example 1 operate, a Biologic SP-300 was used to measure the capacity (mAh)-voltage (V) graph during charging of the battery. The measurement results are shown in FIGS. 4 to 6 attached respectively.

[0104] FIG. 4 is a capacity (mAh)-voltage (V) graph during charging of the lithium secondary battery manufactured in Example 1, FIG. 5 is a capacity (mAh)-voltage (V) graph during charging of the lithium secondary battery manufactured in Example 2, and FIG. 6 is a capacity (mAh)-voltage (V) graph during charging of the lithium secondary battery manufactured in Comparative Example 1.

[0105] As shown in FIGS. 4 to 6, it was confirmed that in Comparative Example 1 where the oxygen barrier member was not used during the curing of the electrolyte, as the capacity of the battery increased during charging, the voltage value of the battery did not increase. This means that in Comparative Example 1, since the electrolyte layer serving as a separator detached from the active material layer, the lithium secondary battery was not charged.

[0106] On the other hand, in Example 1 and Example 2 where the oxygen barrier member was used during the curing of the electrolyte, it was confirmed that during charging, as the capacity of the battery increased, the voltage value of the battery increased. This means that in Example 1 and Example 2, since the electrolyte layer serving as a separator did not detach from the active material layer, the battery could be charged normally.

Claims

1. A step of preparing an electrode; A step of coating an electrolytic solution on the electrode; A step of disposing an oxygen barrier member on the coated electrolytic solution; A method for manufacturing an electrode laminate, comprising: a step of curing the electrolytic solution impregnated inside the electrode and the electrolytic solution coated on the surface of the electrode.

2. The method for manufacturing an electrode laminate according to claim 1, wherein an electrolyte layer is formed on the electrode by curing the electrolytic solution coated on the surface of the electrode.

3. The method for manufacturing an electrode laminate according to claim 1, wherein the oxygen barrier member contains one or more selected from the group consisting of glass, polypropylene (PP), and high density polyethylene (HDPE).

4. The electrolytic solution: Contains 5 wt% to 50 wt% of a monomer; Contains 0.01 wt% to 1 wt% of an initiator; Contains 5 wt% to 30 wt% of a lithium salt. The method for manufacturing an electrode laminate according to claim 1.

5. The monomer according to claim 4 contains one or more selected from the group consisting of ethylene glycol diacrylate, triethylene glycol diacrylate, ethoxylated trimethylolpropane triacrylate (ETPTA), bisphenol A ethoxylated dimethacrylate, acrylic acid, carboxyethyl acrylate, methyl cyanoacrylate, ethyl cyanoacrylate, ethyl cyanoethoxyacrylate, cyano acrylic acid, hydroxyethyl methacrylate, and hydroxypropyl acrylate. The method for manufacturing the electrode laminate according to claim 4.

6. The initiator in the method for manufacturing the electrode laminate according to claim 4 contains at least one selected from the group consisting of HMMP (2-hydroxy-2-methylpropiophenone), 1-hydroxy-cyclohexylphenyl-ketone, benzophenone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester of oxy-phenylacetic acid, 2-[2-hydroxyethoxy]-ethyl ester of oxy-phenyl-acetic acid, α-dimethoxy-α-phenylacetophenone, 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone, diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(η5-2,4-cyclopentadien-1-yl), bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl]titanium, 4-isobutylphenyl-4'-methylphenyliodonium hexafluorophosphate, and methylbenzoylformate.

7. The method for manufacturing the electrode laminate according to any one of claims 1 to 6, wherein the electrolyte layer is formed by photocuring or thermocuring the electrolytic solution.

8. The method for manufacturing the electrode laminate according to claim 1, wherein the content of the solid component in the electrolytic solution is 10% to 60%.

9. The method for manufacturing the electrode laminate according to claim 1, wherein the viscosity of the electrolytic solution at 25°C is 30 cP or less.

10. The method for manufacturing the electrode laminate according to claim 1, wherein the thickness of the electrolyte layer is 10 μm to 200 μm.

11. The method for manufacturing the electrode laminate according to claim 1, wherein the thickness of the electrode is 100 μm or less.

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