Electrode protection element and solid-state battery containing it

Abstract

An electrode protection member and an all-solid-state battery including the same, the electrode protection member comprising a lower structure including a carbon-based tubular body whose surface is functionalized with a hydroxyl group, and a composite resin portion including a thermosetting resin and an ultraviolet-curing resin, the composite resin portion being disposed on the lower structure, and a manufacturing method for the electrode protection member and the all-solid-state battery including the electrode protection member.

Description

BACKGROUNDTechnical area

[0001] The present invention relates to an electrode protection element for protecting an all-solid-state battery from an internal short circuit and a all-solid-state battery containing this element. background

[0002] Due to the depletion of fossil fuels and the increasing demand for sustainable energy, research into low-cost, environmentally friendly, and high-performance energy conversion and storage devices, especially lithium secondary batteries, has made rapid progress. The application range of lithium secondary batteries is expanding not only for small electronic devices, but also for medium- to large-scale energy devices for electric vehicles and energy storage systems (ESS).

[0003] As lithium secondary batteries are used as a power source for electric vehicles, the demand for high-performance, high-energy-density lithium secondary batteries is rapidly increasing. However, existing lithium secondary batteries using flammable liquid electrolytes have limitations, such as safety issues such as leakage, ignition, and explosion due to rapid internal and external environmental changes such as temperature fluctuations and external shocks. Accordingly, there is a need to use a solid electrolyte with more stable and durable properties to replace the existing flammable liquid electrolyte.

[0004] However, in all-solid-state lithium batteries using a solid electrolyte, the area (e.g., region) of the negative electrode coated with the solid electrolyte is larger than that of the positive electrode, so there is a high probability of internal short circuits occurring under high temperature and high pressure conditions. To solve this problem, a technology has been proposed that uses glass or ceramics based on composite oxides with SiO. 2 , MgO, ZnO, Na 2 O, Al 2 O 3 , etc., which are internal short-circuit protection materials for all-solid-state batteries. However, there was a problem that cracks occurred under pressure conditions because the step formed by the area difference (e.g., the area difference) between the negative and positive electrodes was not fully protected.

[0005] In addition, methods of using cured resins such as thermosetting resins or ultraviolet curing resins in addition to the solid materials have been proposed. However, when applying a thermosetting resin or ultraviolet curing resin to the solid electrolyte layer, there was a limitation that either resin would penetrate the solid electrolyte layer, causing a side reaction, or penetrate the contact surface with the positive electrode.

[0006] Accordingly, there is a need to develop an electrode protection element that can prevent internal short circuits and prevent side reactions in solid-state batteries. BRIEF EXPLANATION OF THE INVENTION

[0007] The present invention is intended to solve the above-mentioned problem and to provide an electrode protecting member (e.g., an electrode protecting part) that can prevent any resin from invading a positive electrode, suppress side reactions in an all-solid-state battery (e.g., an all-solid-state battery, a solid-state secondary battery, a pure solid-state battery, a battery containing only solid electrolytes), and firmly bond to the electrode and the solid electrolyte layer by applying (e.g., depositing) a composite resin (e.g., a composite resin, a coated composite resin) containing a thermosetting resin and an ultraviolet curing resin on a carbon-based tubular body whose surface is functionalized with a hydroxy group.

[0008] In one aspect (e.g., in one embodiment), an electrode protection member is provided comprising: 1) a lower structure comprising a carbon-based body (e.g., a carbon-based body, e.g., a carbon-based body) whose surface comprises or is functionalized with one or more hydroxy groups; and 2) a composite resin portion (e.g., a composite resin part) comprising a thermosetting resin and an ultraviolet-curing resin disposed (e.g., distributed, e.g., applied) on the lower structure (e.g., comprising a thermosetting resin and an ultraviolet-curing resin and disposed on the lower structure).

[0009] In aspects (e.g., in further embodiments), the carbon-based body is a tubular body. The carbon-based body may also have other configurations.

[0010] An exemplary embodiment of the present invention provides an electrode protection member comprising a lower structure including a carbon-based tubular body whose surface is functionalized with a hydroxy group, and a composite resin portion including a thermosetting resin and an ultraviolet curing resin disposed on the lower structure.

[0011] The lower structure may be a porous plate-shaped structure in which a plurality of carbon-based tubular bodies are connected to one another by point contact. The porous plate-shaped structure has a porosity of about 60 to about 95%, where the porosity Φ is defined, for example, as 1 minus the quotient of the bulk density ρ (of a solid) or the bulk density ρ (of a heap) and the true density ρ 0 , for example multiplied by 100%, for example Φ = 1 - ρ / ρ 0 , for example Φ = (1 - ρ / ρ 0 ) * 100%. The lower structure may be a web-shaped (e.g., a mesh-shaped) plate-shaped structure in which the plurality of carbon-based tubular bodies are irregularly connected. The lower structure may be a lattice-shaped plate-shaped structure in which the plurality of carbon-based tubular bodies are regularly connected to each other.

[0012] The carbon-based tubular body may be solid or hollow. The carbon-based tubular body may comprise at least one or more selected from the group consisting of carbon fibers, carbon nanotubes, graphene, and a mixture thereof. A surface (e.g., a surface) of the carbon-based tubular body may be functionalized with one or more hydroxy groups or may be treated to provide one or more hydroxy groups, e.g., by treatment with a peroxide-based compound or other suitable agent (e.g., another suitable agent, e.g., another suitable substance).

[0013] When referred to herein, a carbon-based body (including a tubular carbon-based body) may contain at least or up to about 10, 20, 30, 40, 50, 60, 70, 80, 90, 95, 98, 99, or 100 weight percent carbon, based on the total weight of the carbon-based body. In certain aspects, a carbon-based body may contain at least or up to about 50, 60, 70, 80, 90, 95, 98, 99, or 100 weight percent carbon, based on the total weight of the carbon-based body. In still further aspects, a carbon-based body may contain at least or up to about 80, 90, 95, 98, 99, or 100 weight percent carbon, based on the total weight of the carbon-based body.

[0014] The thermosetting resin may be a polyurethane-based polymer (e.g., a polyurethane-based polymer). The polyurethane-based polymer may contain OH functional groups and NCO functional groups in a molar ratio of about 1:1.4 to about 1:1.8.

[0015] The ultraviolet-curing resin may contain an acrylate-based polymer (e.g., an acrylate-based polymer), a reactive diluent, and a photopolymerization initiator. The ultraviolet-curing resin and the thermosetting resin may be present in a weight ratio of about 1:0.4 to about 1:1.

[0016] In certain embodiments, an average thickness of the lower structure is about 10 to about 40 µm.

[0017] The carbon-based tubular body in the lower structure and the thermosetting resin in the composite resin section can be bonded together by a urethane bond.

[0018] Furthermore, another embodiment of the present invention provides an all-solid-state battery comprising a negative electrode, a solid electrolyte layer (e.g., solid electrolyte layer) disposed on a surface of the negative electrode, a positive electrode disposed on a surface (e.g., in a center) of the solid electrolyte layer, and the electrode protecting member disposed on the surface (e.g., the end side) of the solid electrolyte layer on which the positive electrode is not disposed.

[0019] The area (e.g., region) on which the electrode protection member is arranged is about 5 to 10% of the area (e.g., region) of the negative electrode in contact with the solid electrolyte layer.

[0020] Yet another embodiment of the present invention provides a method for manufacturing (e.g., producing) an all-solid-state battery, comprising the steps of arranging and pressing a lower structure comprising a carbon-based tubular body whose surface is functionalized with a hydroxy group on a surface (e.g., the end side) of a solid electrolyte layer on which a positive electrode is not arranged in a laminate, the laminate comprising a negative electrode, the solid electrolyte layer arranged on a surface of the negative electrode, and the solid electrolyte layer arranged on a surface (e.g.,a positive electrode disposed at the center of the solid electrolyte layer; disposing (e.g., applying) a mixture comprising a thermosetting (e.g., a thermosetting) compound and an ultraviolet-curing compound on the lower structure and curing the thermosetting compound; and curing the ultraviolet-curing compound by irradiating the mixture with ultraviolet rays to form a composite resin portion.

[0021] Pressing can be carried out at a temperature of about 20 to about 30 °C and a pressure of about 2 to about 6 MPa.

[0022] The ultraviolet radiation may be irradiated at a dose of about 1000 to about 1500 mW / cm2 and a speed (e.g., of the radiation source, e.g., a speed of the radiation source relative to the mixture for forming the composite resin portion) of about 30 to about 40 mm / s.

[0023] The mixture for producing the composite resin section preferably has a viscosity of about 10,000 to about 15,000 cp (mPa·s).

[0024] By using the electrode protection member of the present invention and the all-solid-state battery containing it, various resins used as the electrode protection member can be prevented from penetrating the electrode and the solid electrolyte layer, thereby suppressing side reactions due to the penetration. Furthermore, by preventing steps due to area differences between the electrodes, an all-solid-state battery with a high stack structure can be realized.

[0025] In addition, the thermosetting resin contained in the composite resin layer (for example, the composite resin) and the lower structure having the carbon-based tubular body functionalized with a hydroxy group form a urethane bond, which is further cured by the ultraviolet curing resin, so that the composite resin layer can be firmly bonded to the lower structure.

[0026] As used herein, the term "all-solid-state battery" (e.g., "all-solid-state battery") includes a rechargeable battery containing a solid-state electrolyte for transferring (e.g., transferring) ions between the battery's electrodes. In aspects (e.g., in some cases), the battery may be a secondary battery.

[0027] In another aspect, a vehicle is provided having a battery as described herein. DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram schematically illustrating a manufacturing method for an all-solid-state battery having an electrode protective material according to an exemplary embodiment of the present invention. Fig. 2 is a diagram illustrating in detail the structure of an electrode protective material according to an exemplary embodiment of the present invention. Fig. Figure 3A is a graph showing a degree of curing as a function of the weight ratio of thermosetting resin and ultraviolet curing resin. Fig. 3B are SEM and CT images of a solid electrolyte layer in contact with an electrode protective material in an all-solid-state battery according to Example 1. Fig. 3C are SEM and CT images of a solid electrolyte layer in contact with an electrode protective material in an all-solid-state battery according to Comparative Example 1. Fig.Figure 4 is a graph showing the capacity retention rates of all-solid-state batteries according to Example 1 and Comparative Example 1 over the course of one cycle. DETAILED DESCRIPTION

[0028] The terminology used herein is for the purpose of describing particular embodiments (e.g., particular example embodiments) only and is not intended to be limiting of the disclosure / invention. As used herein, the singular forms "a," "an," and "the" include the plural forms, unless the context clearly indicates otherwise. These terms (e.g., the terms used herein, such as first, second, lower, upper, etc.) are used only to distinguish one component from another and do not limit the type, order, or ordering of the individual components.It is further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of certain features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the related listed elements. Unless expressly described otherwise, the word "comprise" and variations such as "comprises" or "comprising" are to be understood to mean the inclusion of the recited elements, but not the exclusion of other elements.In addition, the terms “unit”, “er”, “or” and “module” described in the specification refer to units for processing at least one function and one operation and can be implemented by hardware components or software components and combinations thereof.

[0029] Although an exemplary embodiment is described as having a plurality of units for performing the exemplary process, the exemplary processes may also be performed by one or more modules (e.g., by one or more programs). Furthermore, it should be understood that the term controller / controller refers to a hardware device having a memory and a processor and specifically programmed to execute the processes described herein. The memory is configured to store the modules, and the processor is configured to execute the modules to perform one or more processes described further below.

[0030] Unless expressly stated or evident from the context, the term "about" is understood herein to mean within a normal range of tolerance, e.g., within 2 standard deviations of the mean. "About" can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless the context otherwise indicates, all numerical values ​​stated herein are modified by the term "about."

[0031] Hereinafter, an electrode protection member and a solid-state battery including the same will be described in detail so that those skilled in the art can easily carry out the present invention.

[0032] An electrode protection member according to an exemplary embodiment of the present invention includes: a lower structure including a carbon-based tubular body whose surface is functionalized with a hydroxy group; and a composite resin portion including a thermosetting resin and an ultraviolet curing resin disposed on the lower structure.

[0033] The lower structure may be a porous plate-like structure in which a plurality of carbon-based tubular bodies are connected to each other through point contact. Specifically, the lower structure may be a ridge-like (e.g., a mesh-like) plate-like structure in which the plurality of carbon-based tubular bodies are irregularly connected. Alternatively, the lower structure may be a lattice-like plate-like structure in which the plurality of carbon-based tubular bodies are regularly connected to each other. However, as long as the lower structure can provide a space for accommodating the composite resin part, the shape of the lower structure is not necessarily limited thereto.

[0034] The porous plate-shaped structure can have a porosity of about 60 to about 95%, preferably about 65 to about 90%, and more preferably about 70 to about 85%. The porosity refers to the ratio of the total volume of the pores present in the porous plate-shaped structure to the total volume of the porous plate-shaped structure. The porosity of the porous plate-shaped structure can be measured, for example, using mercury intrusion porosimetry (MIP).

[0035] When the porosity of the porous plate-shaped structure satisfies the above-mentioned numerical range, there is sufficient space to accommodate the composite resin portion, so that the combination (e.g., joining) of the lower structure and the composite resin portion is facilitated.

[0036] The average thickness of the lower structure may be about 10 to about 40 μm, preferably about 15 to about 35 μm, and more preferably about 20 to about 30 μm. When the average thickness of the plate-shaped structure satisfies the above-mentioned numerical range, it can effectively prevent the occurrence of side reactions due to the penetration of the composite resin portion into the solid electrolyte layer disposed on a surface of the negative electrode and protect the step formed due to the area difference between the negative and positive electrodes.

[0037] The carbon-based body can be solid or hollow.

[0038] The carbon-based body may comprise at least one or more elements (e.g., components, e.g., compounds) selected from the group consisting of carbon fibers, carbon nanotubes, graphene, and a mixture thereof.

[0039] In particular, the carbon nanotube may comprise at least one selected from the group consisting of a single-walled carbon nanotube, a double-walled carbon nanotube, a multi-walled carbon nanotube, and a bundled carbon nanotube.

[0040] The surface of the carbon-based body can be functionalized with a hydroxyl group by treatment with a peroxide-based compound.

[0041] The peroxide-based compound may, for example, comprise i) hydrogen peroxide; ii) at least one selected from the group consisting of peroxydiphosphoric acid (H 4 P 2 O 8 ), peroxydisulfonic acid (H 4 S 2 O 8 ), phthalimidoperoxycaproic acid, peroxyacetic acid (C 2 H 4 O 3), peroxybenzoic acid, diperoxyphthalic acid, and their salts; or iii) at least one selected from the group consisting of benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, and tert-butylcumyl peroxide.

[0042] By functionalizing the surface of the carbon-based body with a hydroxy group, the carbon-based body can form a more robust bond with the composite resin contained in the electrode protection element, which is accommodated by the lower structure containing the tubular carbon-based body.

[0043] Specifically, the carbon-based body in the lower structure and the thermosetting resin in the composite resin portion can be bonded together by a urethane bond. That is, the hydroxy group deposited on the surface of the carbon body forms a urethane bond with the thermosetting resin contained in the composite resin, so that the carbon body and the composite resin can be firmly bonded together.

[0044] The thermosetting resin may be a polyurethane-based polymer. A polyurethane-based polymer refers to a polymer containing a repeating urethane unit formed by the reaction of an isocyanate and a polyol in a main chain. In this case, the isocyanate is a compound with two or more NCO groups, and the polyol is a compound with three or more hydroxyl groups.

[0045] The NCO group of the polyurethane-based polymer contained in the thermosetting resin reacts with the hydroxy group on the surface of the carbon-based tubular body contained in the lower structure to form the urethane bond, whereby the lower structure and the composite resin portion can be primarily bonded.

[0046] The isocyanate may comprise at least one or more selected from the group consisting of, but not necessarily limited to, toluene diisocyanate (TDI), 4,4-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate (NDI), tolidine diisocyanate (TODI), hexamethylene diisocyanate (HMDI), isoprene diisocyanate (IPDI), p-phenylene diisocyanate, trans-cyclohexane, 1,4-diisocyanate, xylene diisocyanate (XDI), and a mixture thereof.

[0047] Examples of the polyol may include, but are not necessarily limited to, polyether-based polyol, polyester-based polyol, polycarbonate-based polyol, or polyalkylene-based polyol.

[0048] The polyether-based polyol can be obtained by adding alkylene oxide to a polyhydric alcohol with three or more hydroxyl groups, such as trimethylolpropane, glycerin, or pentaerythritol. The alkylene oxide can be, for example, ethylene oxide or propylene oxide.

[0049] The polyester-based polyol can be obtained by reaction of low molecular weight diol, low molecular weight dicarboxylic acid and triol.

[0050] The low molecular weight diol may include, for example, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butadienediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, cyclohexanediol, etc.

[0051] The low molecular weight dicarboxylic acid may include, for example, terephthalic acid, isophthalic acid, 1,5-naphthalic acid, 2,6-naphthalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decamethylenedicarboxylic acid, dodecamethylenedicarboxylic acid, etc.

[0052] Examples of triols may include trimethylolpropane, glycerol, and the like.

[0053] Examples of polycarbonate-based polyols may include polyhexamethylene carbonate polyol, polycyclohexanedimethylene carbonate polyol, and the like.

[0054] Examples of polyalkylene polyols (e.g., polyalkylene-based polyol) may include polybutadiene polyol, hydrogenated polybutadiene polyol, hydrogenated polyisoprene polyol, and the like.

[0055] The polyurethane-based polymer may have OH functional groups and NCO functional groups in a molar ratio of about 1:1.4 to about 1:1.8, preferably about 1:4.5 to about 1:7.5, and more preferably about 1:1.5 to about 1:1.7. When the molar ratio of the OH functional group and the NCO functional group in the polyurethane polymer (for example, the polyurethane-based polymer) satisfies the above numerical range, a polyurethane-based compound having a three-dimensional structure with an NCO functional group at the end can be formed, which allows crosslinking with the hydroxy group present on the surface of the carbon-based tubular body included in the lower structure, thereby forming a strong urethane bond.

[0056] The ultraviolet curing resin may comprise an acrylate-based polymer, a reactive diluent, and a photopolymerization initiator. The ultraviolet curing resin may form a more robust electrode protection element by further combining the lower structure and the composite resin portion through a curing reaction using ultraviolet irradiation.

[0057] The acrylate-based polymer can form a cured film, can influence the physical properties of the final ultraviolet-curing resin, and can enable light curing through an acrylate group, which is a reaction site for UV curing by ultraviolet rays.

[0058] The acrylate-based polymer may comprise at least one or more selected from the group consisting of epoxy acrylate, urethane acrylate, polyester acrylate, polyether acrylate and silicone acrylate.

[0059] The reactive diluent can serve as a crosslinking agent (e.g., crosslinker) for the acrylate-based polymer and adjust the viscosity of the ultraviolet-curing resin to a suitable range.

[0060] The reactive diluent may comprise a radically photocurable compound. In particular, the reactive diluent may comprise a monofunctional acrylate-based monomer.

[0061] The monofunctional acrylate-based monomer may comprise at least one or more selected from the group consisting of, but not necessarily limited to, methyl methacrylate (MMA), ethyl methacrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, ethyl acrylate (HEA), glycidyl methacrylate (GMA), 2-hydroxyethyl methacrylate (2-HEMA), acryloylmorpholine (ACMO), isobornyl acrylate (IBOA), 2-hydroxypropyl methacrylate (2-HPMA), hydroxypropyl acrylate (HPA), ethoxyethoxyethyl acrylate (EOEOEA), butyl acrylate (BA), and a mixture thereof.

[0062] The photopolymerization initiator can be used to initiate polymerization by absorbing ultraviolet rays and generating radicals or cations.

[0063] The photopolymerization initiator may comprise at least one or more selected from the group consisting of benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 4-(2-hydroxyethoxy)phenyl 2(hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-Ethylanthraquinone, 2-Tertiarybutylanthraquinone, 2-Aminoanthraquinone, 2-Methylthioxanthone, 2-Ethylthioxanthone, 2-Chlorothioxanthone, 2,4-Dimethylthioxanthone, 2,4-Diethylthioxanthone, Benzyldimethylketal, Acetophenonedimethylketal and p-Dimethylaminobenzoic acid esters, but are not necessarily limited to these.

[0064] The ultraviolet curing resin and the thermosetting resin may be contained in a weight ratio of about 1:0.4 to about 1:1, preferably about 1:0.4 to about 1:0.6. When the weight ratio of the thermosetting resin and the ultraviolet curing resin satisfies the above-mentioned numerical range, the curing speed of the composite resin is further improved, and it can be fully cured, thereby preventing the composite resin from being impregnated (or penetrated) into the solid electrolyte layer of the all-solid-state battery.

[0065] Another embodiment of the present invention provides an all-solid-state battery comprising: a negative electrode, a solid electrolyte layer disposed on a surface of the negative electrode, a positive electrode disposed on a surface (e.g., in a center) of the solid electrolyte layer, and the electrode protecting member disposed on the surface (e.g., the end side) of the solid electrolyte layer where the positive electrode is not disposed.

[0066] The negative electrode can be prepared by applying a slurry containing a negative electrode active material, a binder, and a conductive material to a negative electrode current collector.

[0067] The negative electrode active material may, for example, comprise one or more selected from the group consisting of natural graphite, artificial graphite, carbonaceous materials, lithium-containing titanium composite oxide (LTO), Si, SiO x , Sn, Li, Zn, Mg, Cd, Ce, Ni or Fe metals (Me), alloys of the above-mentioned metals (Me), the oxides (MeO x ) of the above-mentioned metals (Me) and a composite of the above-mentioned metals (Me) and carbon.

[0068] The binder may, for example, comprise one or more selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose, starch, hydroxypropylcellulose, recycled cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and a copolymer thereof.

[0069] The conductive material may include, but is not necessarily limited to, graphite such as natural or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and gap black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powders; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxide such as titanium oxide; and conductive materials such as polyphenylene derivatives. Any material that exhibits conductivity without causing chemical changes in the battery is suitable as a conductive material.

[0070] The negative electrode current collector may comprise, for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver or the like, or an aluminum-cadmium alloy.

[0071] The type of solid electrolyte contained in the solid electrolyte layer may include, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a polymer-based solid electrolyte, but is not specifically limited thereto.

[0072] The sulfide-based solid electrolyte may comprise a compound represented (for example, represented) by the following formula (1). M 1 a M 2 b S c X 1 d [Formula 1]

[0073] In Formula 1, M 1one or more elements selected from an alkali metal and an alkaline earth metal, and M 2 is Sb, Sn, Mg, Ba, B, Al, Ga, In, Si, Ge, Pb, N, P, As, Bi, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, W or La, X 1 is F, Cl, Br, I, O, Se or Te, 0 <a≤6, 0<b≤6, 0<c≤6, und 0≤d≤6.

[0074] The oxide-based solid electrolyte may comprise at least one or more selected from the group consisting of an LLTO-based compound, Li 6 La 2 CaTa 2 O 12 , Li 6 La 2 ANb 2 O 12 (A=Ca or Sr), Li 2 Nd 3 TeSbO 12 , Li 3 BO 2.5 N 0.5 , Li 9 SiAlO 8 , a LAGP-based connection, a LATP-based connection, Li 1+a1 Ti 2-a1 Al a1 Si b1 (PO 4 ) 3-b1(where 0≤a1≤1, 0≤b1≤1), LiAl a2 Zr 2-a2 (PO 4 ) 3 (where 0≤a2≤1), LiTi a3 Zr 2-a3 (PO 4 ) 3 (where 0≤a3≤1), a LISICON-based compound, a LIPON-based compound, a perovskite-based compound, a Nasicon-based compound, and a LLZO-based compound.

[0075] The polymer-based solid electrolyte may, for example, comprise one or more selected from the group consisting of a polyether-based polymer, a polycarbonate-based polymer, an acrylate-based polymer, a polysiloxane-based polymer, a phosphazene-based polymer, a polyethylene derivative, an alkylene oxide derivative such as polyethylene oxide (PEO), a phosphoric acid ester polymer, a polyagitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, and a polymer containing an ionically dissociable group, but is not necessarily limited thereto.

[0076] The positive electrode can be prepared by applying a slurry containing a positive electrode active material, a binder, and a conductive material to a positive electrode current collector.

[0077] The active material of the positive electrode may, for example, comprise lithium manganese-based oxide such as LiMnO 2 , LiMn 2 O 4 , lithium cobalt-based oxide such as LiCoO 2 , lithium-nickel-based oxide such as LiNiO 2 , oxide based on lithium nickel manganese cobalt such as Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O 2 , Li(Ni 0.6 Mn 0.2 Co 0.2 )O 2 , Li(Ni 0.5 Mn 0.3 Co 0.2 )O 2 , Li(Ni 0.7 Mn 0.15 Co 0.15 )O 2 and Li(Ni 0.8 Mn 0.1 Co 0.1 )O 2 , or lithium nickel cobalt aluminum oxide such as Li(Ni 0.8 Co 0.15 Al 0.05 )O 2 , but is not necessarily limited to it.

[0078] The binder and conductive material may be the same as those described for the negative electrode.

[0079] The positive electrode current collector may comprise, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like, etc.

[0080] The area (e.g., region) on which the electrode protection element is arranged may be about 5 to about 10%, preferably about 5.5 to about 9.5%, and more preferably about 6 to about 9% of the area (e.g., region) of the negative electrode in contact with the solid electrolyte layer.

[0081] The solid electrolyte layer, which has the same area (e.g., the same areal extent, e.g., the same region, e.g., the same range) as the negative electrode, is disposed on a surface (e.g., a surface) of the negative electrode, and the positive electrode is disposed on the solid electrolyte layer, specifically in the center of the solid electrolyte layer. Specifically, the areas (e.g., the areas, e.g., the regions) of the negative electrode and the solid electrolyte layer are larger than the area (e.g., the area, e.g., the region) of the positive electrode. Due to this area difference, the remaining area of ​​the solid electrolyte layer, except for the positive electrode disposed on a surface (e.g., in the center) of the solid electrolyte layer, can be exposed to the outside.The all-solid-state battery according to the present invention has a structure in which the electrode protection member is disposed on the surface (e.g., the end side) of the solid electrolyte layer where the positive electrode is not disposed. This eliminates the area difference caused by the area (e.g., region) of the positive electrode being smaller than the area (e.g., region) of the solid electrolyte layer, and covers the portion (e.g., part) of the surface of the solid electrolyte layer exposed to the outside with the electrode protection member.

[0082] By disposing the electrode protection member of the present invention on the surface (e.g., the end side) of the solid electrolyte layer where the positive electrode is not disposed, the occurrence of cracks under pressure conditions during the manufacture of an all-solid-state battery can be prevented. Furthermore, when applying a conventional thermosetting resin or ultraviolet curing resin, the resin penetrates into the solid electrolyte layer and causes a side reaction, or it penetrates into the positive electrode and forms a step due to the area difference between the electrodes, resulting in the formation of an unstable electrode during the formation of a laminated structure. In contrast, in the present invention, by applying the electrode protection member, side reactions (e.g., side reactions) can be suppressed and an all-solid-state battery with a high stack structure can be formed.

[0083] Another embodiment of the present invention provides a method for manufacturing an all-solid-state battery, comprising the steps of arranging (e.g., applying) and pressing a lower structure comprising a carbon-based tubular body whose surface is functionalized with a hydroxy group on a surface (e.g., the end side) of a solid electrolyte layer where a positive electrode is not arranged in a laminate, the laminate comprising a negative electrode, the solid electrolyte layer arranged on a surface of the negative electrode, and the positive electrode arranged on a surface (e.g., in a center) of the solid electrolyte layer; applying a mixture for forming a composite resin portion comprising a thermosetting (e.g., a thermosetting) compound (i.e.,a compound that is cured by heat) and an ultraviolet curing compound (ie, a compound that is cured by ultraviolet rays) on the lower structure and curing the thermosetting compound; and curing the ultraviolet curing compound by irradiating the pressurized mixture with ultraviolet rays to form the composite resin portion.

[0084] First, the step of arranging and pressing the lower structure comprising the carbon-based tubular body functionalized with a hydroxy group is performed on a surface (e.g., the end side) of the solid electrolyte layer where the positive electrode is disposed in the laminate. The laminate includes: the negative electrode, the solid electrolyte layer disposed on a surface of the negative electrode, and the positive electrode disposed on a surface (e.g., in the center) of the solid electrolyte layer.

[0085] Here, with respect to the negative electrode, the positive electrode, the solid electrolyte layer and the lower structure, the descriptions for the electrode protection element and the all-solid-state battery can be equally applied.

[0086] Pressurization can be performed at a temperature of about 20 to about 30°C and a pressure of about 2 to about 6 MPa, preferably about 2.5 to about 5.5 MPa, and more preferably about 3 to about 5 MPa. When pressurization is performed under the above-mentioned pressure conditions, the porosity of the lower structure reaches about 60 to about 95%, preferably about 65 to about 90%, and more preferably about 70 to about 85%, thereby providing sufficient space to accommodate the composite resin portion.The average thickness of the lower structure is about 10 to about 40 μm, preferably about 15 to about 35 μm, more preferably about 20 to about 30 μm, so that it can effectively suppress the occurrence of side reactions due to the penetration of the composite resin portion into the solid electrolyte layer disposed on a surface of the negative electrode and protect the step formed due to the area difference between the negative and positive electrodes. Meanwhile, the pressurization can be performed for about 4 to about 11 seconds, preferably about 5 to about 10 seconds.

[0087] Subsequently, the step of applying the mixture for forming the composite resin portion containing the thermosetting compound and the ultraviolet curing compound to the lower structure is carried out, and the step of curing the thermosetting compound is carried out.

[0088] The thermosetting compound may comprise a polyurethane-based polymer. The polyurethane-based polymer may have OH functional groups and NCO functional groups in a molar ratio of about 1:1.4 to about 1:1.8, preferably about 1:4.5 to about 1:7.5 (e.g., 1:1.45 to about 1:1.75), and more preferably about 1:1.5 to about 1:1.7. When the molar ratio of the OH functional group and the NCO functional group in the polyurethane-based polymer satisfies the above numerical range, a polyurethane-based compound having a three-dimensional structure with an NCO functional group at the end can be formed, which allows crosslinking with the hydroxy group present on the surface of the carbon-based tubular body included in the lower structure, thereby forming a strong urethane bond.

[0089] When the composite resin portion forming mixture is applied to the lower structure, the NCO group of the thermosetting compound in the composite resin portion forming mixture and the hydroxyl group on the surface of the carbon-based tubular body contained in the lower structure in contact with the composite resin portion forming mixture may first react to form a urethane bond. In this case (for example, at this stage), the composite resin portion forming mixture may be in a semi-cured state that is not fully cured.

[0090] Finally, the step of curing the ultraviolet curing compound is carried out by irradiating the pressurized mixture with ultraviolet rays to form the composite resin portion.

[0091] The ultraviolet curing compound may comprise an acrylate-based polymer, a reactive diluent, and a photopolymerization initiator. The ultraviolet curing compound may form a more robust electrode protection element by further combining the lower structure and the composition for forming the composite resin portion through the curing reaction by ultraviolet irradiation. In this case, the composition for forming the composite resin portion may be in a fully cured state.

[0092] The acrylate-based polymer forms a cured film, can influence the physical properties of the final ultraviolet curing resin, and can enable photocuring through an acrylate group that provides a reaction site for ultraviolet curing by ultraviolet rays.

[0093] The acrylate-based polymer may comprise at least one or more selected from the group consisting of epoxy acrylate, urethane acrylate, polyester acrylate, polyether acrylate and silicone acrylate.

[0094] The reactive diluent serves as a crosslinking agent for the acrylate-based polymer and can be used to adjust the viscosity of the ultraviolet-curing resin to a suitable range (e.g., range of values).

[0095] The reactive diluent may comprise a radically photocurable compound. In particular, the reactive diluent may contain a monofunctional acrylate-based monomer.

[0096] The monofunctional acrylate-based monomer may comprise at least one or more selected from the group consisting of, but not necessarily limited to, methyl methacrylate (MMA), ethyl methacrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, ethyl acrylate (HEA), glycidyl methacrylate (GMA), 2-hydroxyethyl methacrylate (2-HEMA), acryloylmorpholine (ACMO), isobornyl acrylate (IBOA), 2-hydroxypropyl methacrylate (2-HPMA), hydroxypropyl acrylate (HPA), ethoxyethoxyethyl acrylate (EOEOEA), butyl acrylate (BA), and a mixture thereof.

[0097] The photopolymerization initiator can be used to initiate polymerization by absorbing ultraviolet rays and generating radicals or cations.

[0098] The photopolymerization initiator may comprise at least one or more selected from the group consisting of benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 4-(2-hydroxyethoxy)phenyl 2(hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-Ethylanthraquinone, 2-Tertiarybutylanthraquinone, 2-Aminoanthraquinone, 2-Methylthioxanthone, 2-Ethylthioxanthone, 2-Chlorothioxanthone, 2,4-Dimethylthioxanthone, 2,4-Diethylthioxanthone, Benzyldimethylketal, Acetophenonedimethylketal and p-Dimethylaminobenzoic acid esters, but are not necessarily limited to these.

[0099] Ultraviolet radiation can be applied at a dose of about 1000 to about 1500 mW / cm 2 and a speed (e.g., a speed of the radiation source, e.g., a speed of the radiation source relative to the mixture for forming the composite resin section) of about 30 to about 40 mm / s, preferably with a dose of about 1050 to about 1450 mW / cm 2 and a speed of about 32 to about 38 mm / s, more preferably with a dose of about 1100 to about 1400 mW / cm 2and a speed of about 33 to about 37 mm / s. When ultraviolet irradiation is carried out under the above conditions, the composite resin part-forming mixture is fully cured to form a robust electrode protective material on the solid electrolyte layer where the positive electrode is not located, and the step due to the area difference between the negative and positive electrodes can be effectively removed.

[0100] Meanwhile, the irradiation with ultraviolet rays can be carried out for about 20 to about 30 seconds, preferably for about 22 to about 27 seconds.

[0101] The mixture for forming the composite resin portion may have a viscosity of about 10,000 to about 15,000 cp (mPa·s), preferably about 10,500 to about 14,500 cp, and more preferably about 11,000 to about 14,000 cp. When the mixture for forming the composite resin portion has the above viscosity, the formed lower structure and the composite resin portion can be fully cured, and thus the electrode protection function of the electrode protection member can be improved.

[0102] Furthermore, the mixture for forming the composite resin portion may have a solid content of about 10 to about 15%, preferably about 10.5 to about 14.5%, and more preferably about 11 to about 14%, based on the total weight of the mixture. When the mixture for forming the composite resin portion has the solid content, the formed lower structure and the composite resin portion can be fully cured, and thus the electrode protection function of the electrode protection member can be improved.

[0103] The present invention will now be described in more detail with reference to examples. However, these examples are provided for the purpose of further understanding of the present invention, and the scope of the present invention is in no way limited to these examples. <Beispiel 1> Manufacturing 1 of a solid-state battery with an electrode protection material

[0104] An all-solid-state battery was fabricated by stacking a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a negative electrode current collector in this order. Aluminum (Al) was used as the positive electrode current collector, the positive electrode layer containing a positive electrode active material, a conductive material, and a binder was fabricated, and oxide was used as the positive electrode active material.

[0105] In addition, a sulfide-based solid electrolyte with high lithium ion conductivity was coated on the solid electrolyte layer. The negative electrode layer, located on one surface of the solid electrolyte layer, was formed by coating a carbonaceous material, which is an active material for the negative electrode, on a thin metal film containing nickel, which is a current collector of the negative electrode.

[0106] In this case, the area of ​​the positive electrode layer is about 90 to 95% of the area of ​​the solid electrolyte layer.

[0107] Subsequently, carbon nanotubes and hydrogen peroxide were reacted to prepare (for example, fabricate) the hydroxyl-coated bottom structure. The bottom structure was placed on the area difference between the solid electrolyte membrane (for example, the solid electrolyte layer) and the negative electrode, that is, on the solid electrolyte membrane where the negative electrode was not placed. It was then rolled for 7 seconds at 25 °C and a pressure of 4 MPa.

[0108] A mixture slurry for forming the composite resin portion containing an acrylate-based polymer as an ultraviolet curing compound and a polyurethane-based polymer as a thermosetting compound in a weight ratio of 1:0.4 was applied to the lower structure.

[0109] Subsequently, ultraviolet rays with an illumination intensity of 1200 mW / cm2 and a speed of 35 mm / s to completely cure the composite resin mixture slurry (for example, the mixture slurry for forming the composite resin section). <Beispiel 2> Manufacturing 2 of a solid-state battery with an electrode protection material

[0110] An electrode protective material and an all-solid-state battery were prepared in the same manner as in Example 1 except that the weight ratio between the ultraviolet curing compound and the thermosetting compound was 1:0.6. <Beispiel 3> Manufacturing 3 of a solid-state battery with an electrode protection material

[0111] An electrode protective material and an all-solid-state battery were prepared in the same manner as in Example 1 except that the weight ratio between the ultraviolet curing compound and the thermosetting compound was 1:1. <Vergleichsbeispiel 1>Manufacturing 4 of a solid-state battery with an electrode protection material

[0112] An electrode protective material and an all-solid-state battery were prepared in the same manner as in Example 1, except that only the thermosetting compound was applied without the ultraviolet curing compound. <Vergleichsbeispiel 2> Manufacturing 5 of a solid-state battery with an electrode protection material

[0113] An electrode protective material and an all-solid-state battery were prepared in the same manner as in Example 1, except that only the ultraviolet curing compound was applied without the thermosetting compound. <Referenzbeispiel 1> Manufacturing 6 of a solid-state battery with an electrode protection material

[0114] An electrode protective material and an all-solid-state battery were prepared in the same manner as in Example 1 except that the weight ratio between the ultraviolet curing compound and the thermosetting compound was 1:2.5. <Referenzbeispiel 2> Manufacturing 7 of a solid-state battery with an electrode protection material

[0115] An electrode protective material and an all-solid-state battery were prepared in the same manner as in Example 1 except that the weight ratio between the ultraviolet curing compound and the thermosetting compound was 1:1.67. <Vergleichsbeispiel 3> Manufacturing a solid-state battery that does not contain electrode protection material

[0116] An all-solid-state battery was manufactured in the same manner as in Example 1, except that the composite resin mixture slurry was not applied to the lower structure and cured. <Versuchsbeispiel 1>Evaluation of the degree of curing and penetration into a solid electrolyte layer as a function of the weight ratio between ultraviolet curing resin and thermosetting resin

[0117] The electrode protective materials of the all-solid-state batteries according to Example 1, Example 2, Comparative Example 1, Comparative Example 2, Reference Example 1, and Reference Example 2 were immersed in tetrahydrofuran (THF), a solvent. Subsequently, the gel content of the composite resin composition and the penetration of the resin into the solid electrolyte layer were observed depending on the weight ratio of the ultraviolet curing resin and the thermosetting resin contained in the composite resin portion, and are shown in Table 1 below.

[0118] The gel fraction is a value calculated according to equation 1, W 0 is the weight (g) of the sample before immersion and W 24is the weight (g) of the sample after immersion for 24 hours. [Equation 1] Gel content (%) = w24w0×100

[0119] In addition, the penetration of the resin of the composite resin section into the solid electrolyte layer was judged by the naked eye, and the penetration resistance was evaluated according to the following levels. ⊚: No resin penetration was confirmed ◯: Resin penetration was hardly confirmed (e.g. only to a very small extent). Δ: Resin penetration was weakly confirmed (e.g., to a slightly larger extent). X: Significant resin penetration was confirmed [Table 1] Weight ratio between ultraviolet curing resin and thermosetting resin Gel content (%) Penetration into a solid electrolyte layer Example 1 1: 0.4 100 ⊚ Example 2 1:0.6 100 ⊚ Example 3 1:1 82 ○ Comparison example 1 0:1 28 X Comparison example 2 1:0 72 Δ Reference example 1 1:2.5 52 X Reference example 2 1:1.67 74 Δ

[0120] Referring to Fig.3A and Table 1, in Examples 1 to 3, in which the weight ratio between the ultraviolet curing resin and the thermosetting resin of the composite resin portion satisfied the range of 1:0.4 to 1:1, the gel content was 80% or more, and little or no resin penetrated into the composite resin portion. Specifically, in Examples 1 and 2, which satisfied the range of 1:0.4 to 1:0.6, the gel content was 100%, and the resin of the composite resin portion did not penetrate into the solid electrolyte layer at all. In contrast, in Comparative Example 1, Comparative Example 2, Reference Example 1, and Reference Example 2, in which the weight ratios were outside the above-mentioned numerical range, only a part of the composition was converted into a gel form, and some parts of the composition penetrated into the solid electrolyte layer.

[0121] In addition, the Fig. 3B and Fig.3C shows the SEM and CT imaging results of the electrode protection member portions of the all-solid-state batteries according to Example 1 and Comparative Example 1, respectively. In Example 1, it was confirmed that the composition of the composite resin portion did not penetrate into the solid electrolyte, while in Comparative Example 1, it was confirmed that penetration into the solid electrolyte occurred. <Experimentelles Beispiel 2> Performance evaluation of a solid-state battery with an electrode protection material

[0122] The capacity retention rates as a function of cycle progress (e.g., progression in repeated charging and discharging cycles) were measured for the solid-state batteries including the electrode protection materials according to Example 1 and Comparative Example 3 and are shown in Fig. 4. Here, the discharge was carried out under conditions of 200 mA / cm 2 up to 300 mA / cm 2 carried out.

[0123] As the cycle progressed, it was confirmed that Example 1 exhibited a higher capacity retention rate compared to Comparative Example 3. This is because the electrode protective material is tightly seated in the formed step due to the size difference between the positive and negative electrodes, effectively suppressing the penetration of the composition within the composite resin portion into the solid electrolyte.

Claims

[1] Electrode protection element comprising: a lower structure comprising a carbon-based body whose surface comprises or is functionalized with one or more hydroxy groups; and a composite resin portion comprising a thermosetting resin and an ultraviolet curing resin and disposed on the lower structure. [2] The electrode protection member according to claim 1, wherein the carbon-based body is a carbon-based tubular body. [3] The electrode protecting member according to claim 1 or 2, wherein the lower structure is a porous plate-shaped structure in which a plurality of the carbon-based bodies are joined to each other by point contact. [4] The electrode protecting member according to claim 2, wherein the lower structure is a mesh-like plate-like structure in which the plurality of carbon-based bodies are irregularly connected to each other. [5] The electrode protecting member according to claim 2, wherein the lower structure is a lattice-shaped plate-shaped structure in which the plurality of carbon-based bodies are regularly connected. [6] An electrode protection element according to any one of claims 1 to 5, wherein the carbon-based body is solid or hollow. [7] The electrode protection member according to any one of claims 1 to 6, wherein the carbon-based body comprises at least one or more selected from the group consisting of carbon fibers, carbon nanotubes, graphene, and a mixture thereof. [8] An electrode protection element according to any one of claims 1 to 7, wherein a surface of the carbon-based body is functionalized with a hydroxy group by treatment with a peroxide-based compound. [9] An electrode protection element according to any one of claims 1 to 8, wherein the thermosetting resin is a polyurethane-based polymer. [10] The electrode protection element according to claim 9, wherein the polyurethane-based polymer has functional OH groups and functional NCO groups in a molar ratio of about 1:1.4 to about 1:1.

8. [11] The electrode protection member according to any one of claims 1 to 10, wherein the ultraviolet curing resin comprises an acrylate-based polymer, a reactive diluent and a photopolymerization initiator. [12] The electrode protection member according to any one of claims 1 to 11, wherein the ultraviolet curing resin and the thermosetting resin are contained in a weight ratio of about 1:0.4 to about 1:

1. [13] Electrode protection element according to claim 3 or according to any one of claims 4 to 12 dependent on claim 3, wherein the porous plate-shaped structure has a porosity of about 60 to about 95%. [14] The electrode protection member according to any one of claims 1 to 13, wherein the average thickness of the lower structure is about 10 to about 40 µm. [15] An electrode protection member according to claim 2 or any one of claims 3 to 14 dependent on claim 2, wherein the carbon-based tubular body in the lower structure and the thermosetting resin in the composite resin portion are bonded together by a urethane bond. [16] Solid-state battery comprising: a negative electrode; a solid electrolyte layer disposed on a surface of the negative electrode; a positive electrode disposed on a surface of the solid electrolyte layer; and the electrode protection member according to any one of claims 1 to 15, which is arranged on the surface of the solid electrolyte layer on which the positive electrode is not arranged. [17] The all-solid-state battery according to claim 16, wherein an area on which the electrode protection member is disposed is about 5 to about 10% of an area of ​​the negative electrode in contact with the solid electrolyte layer. [18] A method for producing a solid-state battery, the method comprising the steps of: Arranging and pressing a lower structure comprising a carbon-based body whose surface is functionalized with a hydroxy group or has a hydroxy group on a surface of a solid electrolyte layer on which a positive electrode is not arranged in a laminate, the laminate comprising a negative electrode, the solid electrolyte layer arranged on a surface of the negative electrode, and the positive electrode arranged on a surface of the solid electrolyte layer; Applying a mixture comprising a thermosetting compound and an ultraviolet curing compound to the lower structure and curing the thermosetting compound; and Curing the ultraviolet curing compound by irradiating the mixture with ultraviolet rays to form a composite resin portion. [19] The method of claim 18, wherein the pressing is carried out at a temperature of about 20 to about 30°C and a pressure of about 2 to about 6 MPa. [20] The method of claim 18, wherein the ultraviolet radiation is applied at a dose of about 1000 to about 1500 mW / cm 2 and irradiated at a speed of about 30 to about 40 mm / s, and wherein the mixture for forming the composite resin portion has a viscosity of about 10,000 to about 15,000 cp.

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