Solid electrolyte-electrode composite, method for producing solid electrolyte-electrode composite, and all-solid-state battery including the solid electrolyte-electrode composite

Abstract

The present invention relates to a method for manufacturing a solid electrolyte-electrode composite, comprising the steps of impregnating an electrode with an electrolyte precursor composition containing a photocrosslinkable monomer containing three or more acrylate groups, an initiator, a lithium salt, and an organic solvent; photocuring the electrode impregnated with the electrolyte precursor composition to form a polymer electrolyte membrane; and thermally curing the electrode on which the polymer electrolyte membrane is formed. In Fourier transform infrared spectroscopic analysis, no peak appears in the wavenumber range of 1,700 cm -1 to 1,600 cm -1 . The present invention also relates to a solid electrolyte-electrode composite and an all-solid-state battery including the solid electrolyte-electrode composite.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0101638 filed on August 12, 2022 and Korean Patent Application No. 10-2023-0105636 filed on August 11, 2023, and all of its contents are incorporated herein by reference.

[0002] The present invention relates to a solid electrolyte-electrode composite, a method for manufacturing the solid electrolyte-electrode composite, and an all-solid-state battery including the solid electrolyte-electrode composite.

Background Art

[0003] Lithium secondary batteries can be miniaturized, have high energy density and operating voltage, and are applied in various fields such as mobile devices, electronic products, and electric vehicles. As the application fields of lithium secondary batteries diversify, the required physical property conditions are gradually increasing, and in particular, the development of lithium secondary batteries that can stably operate in various environments is demanded.

[0004] Generally, a secondary battery is manufactured by mounting an electrode assembly composed of a negative electrode, a positive electrode, and a separator inside a case having a certain space such as a cylindrical shape, a rectangular shape, or a pouch type, and injecting an electrolyte into the electrode assembly.

[0005] Conventionally, as an electrolyte for electrochemical elements, a liquid electrolyte in which a salt is dissolved in a non-aqueous organic solvent has been mainly used. However, such a liquid electrolyte induces degradation of the electrode material, has a high volatility of the organic solvent, and combustion due to an increase in temperature may occur, and there is a concern about leakage, making it difficult to realize various forms of electrochemical elements that require safety.

[0006] Therefore, extensive research has been conducted on all-solid-state batteries using solid electrolytes with higher electrochemical stability than liquid electrolytes. However, there is a current limitation that it is difficult to achieve complete curing of the electrolyte solution present inside the electrode during curing for forming the solid electrolyte.

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention is for solving the above problems, and aims to provide a solid electrolyte-electrode composite in which complete curing is performed and unreacted monomers are not detected.

[0008] Also, by performing both photo-curing and heat-curing, it aims to provide a method for manufacturing a solid electrolyte-electrode composite capable of increasing the degree of curing of the electrolyte.

[0009] Also, it aims to provide an all-solid-state battery including the solid electrolyte-electrode composite.

Means for Solving the Problems

[0010] According to one embodiment, the present invention provides a solid electrolyte-electrode composite in which no peak appears in the wavenumber range of 1,700 cm -1 ~1,600 cm -1 during Fourier transform infrared spectroscopy.

[0011] Also, the present invention provides a method for manufacturing a solid electrolyte-electrode composite, including the steps of impregnating an electrode with an electrolyte precursor composition containing a photo-crosslinkable monomer containing three or more acrylate groups, an initiator, a lithium salt, and an organic solvent; photo-curing the electrode impregnated with the electrolyte precursor composition to form a polymer electrolyte membrane; and heat-curing the electrode on which the polymer electrolyte membrane is formed.

[0012] Also, the present invention provides an all-solid-state battery including the solid electrolyte-electrode composite.

Effects of the Invention

[0013] The solid electrolyte-electrode composite according to the present invention includes a strong polymer electrolyte membrane that has been completely polymerized without unreacted monomers, and thus can improve the charging performance of the battery by preventing the problem of electrolyte leakage from the electrode and causing a short circuit.

[0014] On the one hand, the method for manufacturing a solid electrolyte-electrode composite according to the present invention uses a substance containing three or more acrylate groups to increase the crosslinking density by photocuring and thermocuring so that complete polymerization can be achieved. Therefore, not only the surface of the electrode but also the inside of the electrode has no remaining electrolyte precursor solution and can be completely cured, which is excellent in processability and safety.

[0015] Ultimately, the present invention has the advantage of being able to provide a battery with improved safety in various driving environments.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0017] Hereinafter, the present invention will be described in more detail.

[0018] [Solid Electrolyte-Electrode Composite] First, the solid electrolyte-electrode composite of the present invention will be described.

[0019] The solid electrolyte-electrode composite according to the present invention, during Fourier transform infrared spectroscopy (FTIR) analysis, has a range of 1,700 cm -1 ~1,600 cm -1There is no peak appearing in the wavenumber region of. The peak observed in the wavenumber region of 1,700 cm -1 ~1,600 cm -1 is due to the stretching vibration (C=C stretching vibration) in the C=C plane, which means that unreacted monomers that have not cured remain inside the electrode. However, since the solid electrolyte-electrode composite according to the present invention has been polymerized 100% without residual monomers, there is no peak appearing in the wavenumber region of 1,700 cm -1 ~1,600 cm -1 .

[0020] On the other hand, the fact that no peak appears means that no peak is visually observed on the spectrum. For example, it means that the transmittance at a wavenumber of about 10 cm -1 does not change by more than 10%.

[0021] At this time, the solid electrolyte-electrode composite means a state in which the electrolyte precursor composition infiltrated into the electrode has cured to form a cross-linked structure. At this time, the solid electrolyte can be in a gelled state or a completely solidified state.

[0022] In one embodiment of the present invention, the thickness of the solid electrolyte-electrode composite may be 60 μm to 200 μm, preferably 80 μm to 200 μm, and more preferably 100 μm to 200 μm.

[0023] On the other hand, in the solid electrolyte-electrode composite, the electrode may be a positive electrode or a negative electrode, and the thickness of the electrode may be 50 μm to 150 μm.

[0024] Also, in the solid electrolyte-electrode composite, the solid electrolyte can serve as a separator, but if necessary, a separator can be further included between the positive electrode and the negative electrode.

[0025] Hereinafter, the positive electrode, the negative electrode, and the separator will be described in more detail.

[0026] (a) Positive electrode The positive electrode contains a positive electrode active material, and can be manufactured by coating a positive electrode slurry containing the positive electrode active material, a binder, a conductive material, a solvent, etc. on a positive electrode current collector, followed by drying and rolling.

[0027] The positive electrode current collector is not particularly limited as long as it has conductivity without inducing a chemical change in the battery. For example, stainless steel; aluminum; nickel; titanium; fired carbon; or those obtained by surface-treating the surface of aluminum or stainless steel with carbon, nickel, titanium, silver, etc. can be used.

[0028] As the positive electrode active material, a lithium transition metal oxide can be used, and it can be used without limitation as long as insertion or desorption of lithium ions easily occurs during charge and discharge. For example, it can contain one or more selected from the group consisting of lithium nickel cobalt-based composite oxides, lithium manganese-based composite oxides, and lithium iron phosphate-based composite oxides, and preferably can contain a lithium nickel cobalt-based composite oxide.

[0029] Specifically, the lithium nickel cobalt-based composite oxide can have the composition of the following Chemical Formula 1.

[0030] [Chemical Formula 1] Li 1+x (Ni a Co b Mn c M d )O2

[0031] In Chemical Formula 1, M is one or more selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, 1 + x, a, b, c, and d are respectively the molar ratios of independent elements, -0.2 ≦ x ≦ 0.2, 0.60 ≦ a < 1, 0 < b ≦ 0.30, 0 < c ≦ 0.30, 0 ≦ d ≦ 0.10, and a + b + c + d = 1.

[0032] The 1 + x represents the molar ratio of lithium in the lithium nickel cobalt composite oxide, and it can be -0.1 ≦ x ≦ 0.2 or 0 ≦ x ≦ 0.2. When the molar ratio of lithium satisfies the above range, the crystal structure of the lithium nickel cobalt composite oxide can be stably formed.

[0033] The a represents the molar ratio of nickel among all the metals excluding lithium in the lithium nickel cobalt composite oxide, and it can be 0.70 ≦ a < 1, 0.75 ≦ a < 1, or 0.80 ≦ a < 1. When the molar ratio of nickel satisfies the above range, it shows a high energy density and enables the realization of a high capacity.

[0034] The b represents the molar ratio of cobalt among all the metals excluding lithium in the lithium nickel cobalt composite oxide, and it can be 0 < b ≦ 0.20, 0 < b ≦ 0.15, or 0 < b ≦ 0.10. When the molar ratio of cobalt satisfies the above range, good resistance characteristics and output characteristics can be realized.

[0035] The c represents the molar ratio of manganese among all the metals excluding lithium in the lithium nickel cobalt composite oxide, and it can be 0 < c ≦ 0.20, 0 < c ≦ 0.15, or 0 < c ≦ 0.10. When the molar ratio of manganese satisfies the above range, excellent structural stability of the positive electrode active material appears.

[0036] In one embodiment of the present invention, the lithium nickel cobalt composite oxide can contain one or more doping elements selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo. Preferably, it can contain Al as a doping element. In other words, among all the metals excluding lithium in the lithium composite transition metal oxide, the d representing the molar ratio of the doping element may be 0 < d ≤ 0.10, 0 < d ≤ 0.08, or 0 < d ≤ 0.05.

[0037] Preferably, a, b, c, and d may be 0.70 ≤ a < 1, 0 < b ≤ 0.2, 0 < c ≤ 0.2, and 0 ≤ d ≤ 0.1, respectively.

[0038] The lithium manganese composite oxide is Li p Mn 1-q M a q A2, Li p Mn2O 4-r X r 、Li p Mn 2-q M a q M b r A4, Li p Co 1-q M a q A2, Li p Co 1-q M a q O 2-r X r 、Li p Ni 1-q M a q O 2-r X r 、Li p Ni 1-q Co q O 2-r X r 、Li p Ni 1-q-r Co q M a r A w, Li p Ni 1-q-r Co q M a r O 2-w X w , Li p Ni 1-q-r Mn q M a r A w and Li p Ni 1-q-r Mn q M a r O 2-w X w may be one or more selected from the group consisting of, wherein p, q, r, and w are 0.9 ≦ p ≦ 1.2, 0 ≦ q ≦ 1, 0 ≦ r ≦ 1, and 0 ≦ w ≦ 2, respectively, and M a and M b are the same as or different from each other and are one or more elements selected from the group consisting of Mg, Al, Co, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As, Zr, Mn, Cr, Fe, Sr, V, and rare earth elements, A is one or more elements selected from the group consisting of O, F, S, and P, and X is one or more elements selected from the group consisting of F, S, and P.

[0039] The lithium iron phosphate-based composite oxide can be represented by the following Chemical Formula 2.

[0040] [Chemical Formula 2] LiFe 1-k M c k PO4

[0041] In Chemical Formula 2, M c is one or more selected from Ni, Co, Mn, Al, Mg, Y, Zn, In, Ru, Sn, Sb, Ti, Te, Nb, Mo, Cr, Zr, W, Ir, and V, 0 ≦ k < 1.

[0042] On the one hand, the positive electrode active material can be contained in an amount of 80% by weight to 99% by weight, specifically 90% by weight to 99% by weight, based on the total weight of the solid content in the positive electrode slurry. At this time, if the content of the positive electrode active material is less than 80% by weight, the energy density may decrease and the capacity may decline.

[0043] The binder is a component that helps bind the active material, conductive material, etc. and bind to the current collector. Usually, it can be added in an amount of 1% by weight to 30% by weight based on the total weight of the solid content in the positive electrode slurry. Examples of such binders may include polyvinylidene fluoride, 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, or various copolymers thereof.

[0044] In addition, the conductive material is a substance that imparts conductivity without inducing a chemical change in the battery, and can be added in an amount of 0.5% by weight to 20% by weight based on the total weight of the solid content in the positive electrode slurry.

[0045] The conductive material can be selected from, for example, carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; graphite powders such as natural graphite, artificial graphite, carbon nanotubes, and graphite; conductive fibers such as carbon fibers and metal fibers; conductive powders such as carbon fluoride powder, aluminum powder, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0046] Further, the solvent of the positive electrode slurry can contain an organic solvent such as NMP (N-methyl-2-pyrrolidone), and when containing the positive electrode active material, binder, conductive material, etc., it can be used in an amount that results in a preferable viscosity. For example, the solid content concentration in the positive electrode slurry containing the positive electrode active material, binder, and conductive material may be included so as to be 40% by weight to 90% by weight, preferably 50% by weight to 80% by weight.

[0047] (b) Negative electrode The negative electrode according to the present invention contains a negative electrode active material, and can be manufactured by coating a negative electrode slurry containing the negative electrode active material, binder, conductive material, solvent, etc. on a negative electrode current collector, followed by drying and rolling.

[0048] The negative electrode current collector is not particularly limited as long as it has high conductivity without inducing a chemical change in the battery. For example, copper; stainless steel; aluminum; nickel; titanium; fired carbon; a surface-treated product of copper or stainless steel with carbon, nickel, titanium, silver, etc.; or an aluminum-cadmium alloy, etc. can be used. Also, similar to the positive electrode current collector, fine irregularities can be formed on the surface to strengthen the binding force of the negative electrode active material, and it can be used in various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric body, etc.

[0049] Further, the negative electrode active material can contain one or more selected from carbon-based materials that can reversibly intercalate / deintercalate lithium ions; metals or alloys of these metals and lithium; metal composite oxides; substances that can dope and undope lithium; lithium metal; and transition metal oxides, and preferably may be a carbon-based material.

[0050] As the carbonaceous material capable of reversibly intercalating / deintercalating the lithium ions, any carbonaceous negative electrode active material generally used in lithium ion secondary batteries can be used without particular limitation. Representative examples thereof include crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flaky, spherical or fibrous natural graphite or artificial graphite. Examples of the amorphous carbon include soft carbon (low-temperature calcined carbon), hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0051] As the metal or an alloy of these metals and lithium, a metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al and Sn or an alloy of these metals and lithium can be used.

[0052] Examples of the metal composite oxide include PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5, Li x Fe2O3 (0 ≦ x ≦ 1), Li x WO2 (0 ≦ x ≦ 1) and Sn x Me 1-x Me’ y O z (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8), and one or more selected from the group can be used.

[0053] As the substance capable of doping and undoping lithium, Si, SiO x(0 < x ≤ 2), Si-Y alloy (wherein Y is an element selected from the group consisting of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a transition metal, a rare earth element, and combinations thereof, and is not Si), Sn, SnO2, Sn-Y (wherein Y is an element selected from the group consisting of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a transition metal, a rare earth element, and combinations thereof, and is not Sn), etc. may be mentioned, and at least one of these may be mixed with SiO2 and used. The element Y can be selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db (dubnium), Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof.

[0054] Examples of the transition metal oxide include lithium-containing titanium composite oxide (LTO), vanadium oxide, lithium vanadate, etc.

[0055] The negative electrode active material can be contained at 80% by weight to 99% by weight based on the total weight of the solid content in the negative electrode slurry.

[0056] The binder is a component that aids in the bonding between the conductive material, the active material, and the current collector, and can usually be added at a content of 1% by weight to 30% by weight based on the total weight of the solid content in the negative electrode slurry. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, or various copolymers thereof.

[0057] The conductive material is a component for further improving the conductivity of the negative electrode active material, and can be added in an amount of 0.5% by weight to 20% by weight based on the total weight of the solid content in the negative electrode slurry. Such a conductive material is not particularly limited as long as it has conductivity without inducing a chemical change in the battery. For example, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; graphite powder such as natural graphite, artificial graphite, carbon nanotube or graphite with a highly developed crystal structure; conductive fibers such as carbon fibers or metal fibers; conductive powders such as carbon fluoride powder, aluminum powder or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive materials such as polyphenylene derivatives can be used.

[0058] The solvent of the negative electrode slurry can contain water; or organic solvents such as NMP and alcohol, and can be used in an amount that provides a preferable viscosity when containing the negative electrode active material, binder, conductive material, etc. For example, the solid content concentration in the slurry containing the negative electrode active material, binder, and conductive material may be included so as to be 30% by weight to 80% by weight, preferably 40% by weight to 70% by weight.

[0059] (c) Separator The separator separates the negative electrode and the positive electrode and provides a migration path for lithium ions. Usually, any separator that can be used in a lithium secondary battery can be used without particular limitation.

[0060] Specifically, as the separator, a porous polymer film, for example, a porous polymer film made of polyolefin-based polymers such as homopolymer of ethylene, homopolymer of propylene, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer; or a laminate structure of two or more layers thereof can be used. Also, a normal porous nonwoven fabric, for example, a nonwoven fabric made of high-melting glass fibers, polyethylene terephthalate fibers, etc. can also be used. In addition, in order to ensure heat resistance or mechanical strength, a coated separator containing a ceramic component or a polymer substance may be used, and it may be used in a single-layer or multilayer structure.

[0061] On the other hand, the solid electrolyte-electrode composite according to the present invention can be manufactured, for example, by the manufacturing method of the solid electrolyte-electrode composite described later.

[0062] [Manufacturing Method of Solid Electrolyte-Electrode Composite] Next, the manufacturing method of the solid electrolyte-electrode composite according to the present invention will be described.

[0063] When manufacturing the solid electrolyte-electrode composite, after applying an electrolyte precursor solution on the electrode, a curing process is required so that the monomers contained in the electrolyte precursor solution can be crosslinked and polymerized. At this time, generally, photocuring is performed by UV irradiation. Although curing by UV is easy on the surface of the electrode, there is a problem that UV hardly penetrates completely into the electrode. For this reason, there is also a possibility that the precursor electrolyte solution remaining inside the electrode leaks out during the process and the progress of the process itself becomes impossible.

[0064] Even when the curing process proceeds by heat curing, it is not preferable in that the electrolyte evaporates due to heat and it is difficult to form a film-like polymer electrolyte membrane on the surface.

[0065] Therefore, the inventors of the present invention introduced a method in which, after applying an electrolyte onto an electrode, first, photocuring by UV is applied to form a polymerized electrolyte film on the surface of the electrode, and then thermosetting is applied. Since there is a polymerized electrolyte film on the surface, it is possible to prevent the uncured electrolyte precursor solution from evaporating or leaking during subsequent thermosetting. As a result, not only on the surface of the electrode but also inside the electrode, unreacted monomers do not remain and can be completely polymerized, which can improve the efficiency and stability of the process, and can provide an all-solid-state battery with excellent safety even in a harsh driving environment.

[0066] Hereinafter, each step will be described in more detail.

[0067] 1) Step of impregnating an electrode with an electrolyte precursor composition The method for manufacturing a solid electrolyte-electrode composite according to an embodiment of the present invention includes a step of impregnating an electrode with an electrolyte precursor composition. For example, by blade coating on the surface of the electrode, cm 2 10 μl to 100 μl, preferably 20 μl to 80 μl, and more preferably 30 μl to 70 μl of the electrolyte precursor composition per cm can be applied and impregnated in a vacuum state for 10 seconds to 60 seconds. When the content of the electrolyte precursor composition is within the above range, a polymer electrolyte film can be easily formed by UV curing.

[0068] In an embodiment of the present invention, the electrolyte precursor composition includes a photocrosslinkable monomer, an initiator, a lithium salt, and an organic solvent. Hereinafter, the constitution of the electrolyte precursor composition will be described in more detail.

[0069] (a) Photocrosslinkable monomer The photo-crosslinkable monomer should be capable of both photo-crosslinking and thermal crosslinking, and should contain three or more acrylate groups. For example, it may be one or more selected from the group consisting of ethoxylated trimethylolpropane triacrylate (ETPTA), trimethylolpropane ethoxytriacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and tris(2-hydroxyethyl) isocyanurate triacrylate. Preferably, it may be ethoxylated trimethylolpropane triacrylate (ETPTA).

[0070] Since the photo-crosslinkable monomer contains three or more acrylate groups, it has the characteristic of a high crosslinking density by photo-crosslinking and thermal crosslinking. Therefore, when the manufacturing method of the present invention is applied, there is an advantage that the degree of polymerization is significantly higher than that of a long-chain photo-crosslinkable monomer such as polypropylene glycol diacrylate, which is mainly used when trying to maximize the function as a liquid electrolyte by minimizing the degree of curing.

[0071] Based on the total weight of the electrolyte precursor composition, the content of the photo-crosslinkable monomer may be 1 wt% to 30 wt%, preferably 5 wt% to 30 wt%, and more preferably 5 wt% to 25 wt%. In order to form a polymer crosslinked structure, it is preferable that the content of the photo-crosslinkable monomer is 1 wt% or more, and in order to maintain the ionic conductivity of the electrolyte at a certain level or higher, it is preferable not to exceed 30 wt%.

[0072] (b) Initiator The initiator may contain a photoinitiator and a thermal initiator, or may contain an initiator that reacts to both light and heat.

[0073] The photoinitiator is not particularly limited as long as it is a compound capable of forming radicals by light such as ultraviolet light. For example, 2-hydroxy-2-methylpropiophenone (HMPP), 1-hydroxy-cyclohexylphenyl-ketone, benzophenone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, oxy-phenylacetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester, oxy-phenyl-acetic 2-[2-hydroxyethoxy]-ethyl ester, 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) may be one or more selected from the group consisting of, and preferably, 2-hydroxy-2-methylpropiophenone (HMPP) may also be used.

[0074] The thermal initiator is not particularly limited as long as it is a compound capable of forming radicals by heat. For example, it may be one or more 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), and preferably may be AIBN.

[0075] The initiator that reacts to both light and heat is not particularly limited as long as it is a compound capable of forming radicals by light and heat.

[0076] Based on the weight of the monomer in the electrolyte precursor composition, the total content of the initiator may be 0.2% by weight to 5% by weight, preferably 0.2% by weight to 2% by weight, and more preferably 0.5% by weight to 1.5% by weight. When within the above range, sufficient curing can be achieved so that no excessive amount of the initiator remains.

[0077] (c) Lithium salt The lithium salt that is usually used in the electrolyte for lithium secondary batteries can be used without limitation. Specifically, the lithium salt contains Li as a cation + and, as an anion, F - , Cl - , Br - , I -, NO3 - , N(CN)2 - , BF4 - , ClO4 - , B 10 Cl 10 - , AlCl4 - , AlO2 - , PF6 - , CF3SO3 - , CH3CO2 - , CF3CO2 - , AsF6 - , SbF6 - , CH3SO3 - , (CF3CF2SO2)2N - , (CF3SO2)2N - , (FSO2)2N - , BF2C2O4 - , BC4O8 - , BF2C2O4CHF-, PF4C2O4 - , PF2C4O8 - , PO2F2 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , C4F9SO3 - , CF3CF2SO3 - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , CF3(CF2)7SO3 - and SCN - can include one or more selected from among them.

[0078] Specifically, the lithium salt may be one or more selected from the group consisting of LiPF6, LiClO4, LiBF4, lithium bis(fluorosulfonyl)imide (LiN(FSO2)2; LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium trifluoromethanesulfonate (LiSO3CF3), lithium difluorophosphate (LiPO2F2), lithium bis(oxalate)borate (LiBOB), lithium difluoro(oxalate)borate (LiFOB), lithium difluoro(bisoxalate)phosphate (LiDFOP), lithium tetrafluoro(oxalate)phosphate (LiTFOP), and lithium fluoromalonate(difluoro)borate; LiFMDFB), and preferably, it may be one or more selected from the group consisting of LiPF6, LiClO4, LiBF4, LiFSI and LiTFSI.

[0079] In one embodiment of the present invention, the concentration of the lithium salt in the electrolyte precursor composition may be 0.5 M to 4.0 M, preferably 0.8 M to 2.0 M.

[0080] From the perspective of improving the ionic conductivity, it is preferable that the concentration of the lithium salt is 0.5 M or more. However, if it exceeds 4.0 M, the salt may prevent the polymerization of the photocrosslinkable monomer.

[0081] (d) Organic solvent As the organic solvent of the electrolyte precursor composition, one or more selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), fluorinated ethylene carbonate (FEC), diethyl carbonate (DEC), G-butyrolactone (GBL), sulfolane (SL), and succinonitrile (SN) can be used. Since the present invention includes a thermosetting stage, the organic solvent must have a boiling point exceeding the temperature at which the thermosetting is performed. For example, when thermosetting is carried out at 80°C, the boiling point of the organic solvent can exceed 80°C.

[0082] Among the total weight of the electrolyte precursor composition, the remainder excluding the contents of other components excluding the organic solvent, such as the photocrosslinkable monomer, initiator, lithium salt, and the following additives, may all be the organic solvent unless otherwise specified.

[0083] The electrolyte precursor composition according to the present invention can further contain one or more additives selected from cyclic carbonate compounds, sultone compounds, sulfate compounds, phosphorus compounds, nitrile compounds, amine compounds, silane compounds, benzene compounds, and lithium salt compounds, if necessary.

[0084] The cyclic carbonate compound may be one or more selected from the group consisting of vinylene carbonate (VC), vinyl ethylene carbonate (VEC), and fluoroethylene carbonate (FEC), and specifically, it may be vinylene carbonate.

[0085] The above-mentioned sultone compound is a substance capable of forming a stable SEI film by a reduction reaction on the surface of the negative electrode, and may be one or more compounds selected from the group consisting of 1,3-propanesultone (PS), 1,4-butanesultone, ethylenesultone, prop-1-ene-1,3-sultone (PRS), 1,4-butene sultone, and 1-methyl-1,3-propene sultone, and specifically may be 1,3-propanesultone (PS) or prop-1-ene-1,3-sultone (PRS).

[0086] The above-mentioned sulfate compound is a substance capable of being electrically decomposed on the surface of the negative electrode and forming a stable SEI film that does not crack even during high-temperature storage, and may be one or more selected from the group consisting of ethylene sulfate (Ethylene Sulfate; Esa), trimethylene sulfate (Trimethylene sulfate; TMS), or methyl trimethylene sulfate (Methyl trimethylene sulfate; MTMS).

[0087] The above-mentioned phosphorus compound may be a phosphate-based or phosphite-based compound, and specifically may be one or more selected from the group consisting of tris(trimethylsilyl) phosphate, tris(trimethylsilyl) phosphite, tris(2,2,2-trifluoroethyl) phosphate, and tris(trifluoroethyl) phosphite.

[0088] The nitrile compound may be at least one selected from the group consisting of succinonitrile (SN), adiponitrile (ADN), acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, 4-fluorophenylacetonitrile, ethylene glycol bis(2-cyanoethyl) ether (ASA3), 1,3,6-hexanetricarbonitrile (HTCN), 1,4-dicyano-2-butene (DCB), and 1,2,3-tris(2-cyanoethyl)propane (TCEP).

[0089] The amine compound may be at least one selected from the group consisting of triethanolamine and ethylenediamine, and the silane compound may be tetravinylsilane.

[0090] The benzene compound may be at least one selected from the group consisting of monofluorobenzene, difluorobenzene, trifluorobenzene, and tetrafluorobenzene.

[0091] The lithium salt compound is a compound different from the lithium salt contained in the non-aqueous electrolyte, and may be at least one compound selected from the group consisting of lithium difluorophosphate (LiDFP; LiPO2F2), lithium bisoxalate borate (LiBOB; LiB(C2O4)2), lithium tetrafluoroborate (LiBF4), lithium tetraphenylborate, lithium difluoro(oxalate) borate (LiDFOB), and lithium difluoro(bisoxalate) phosphate (LiDFOP).

[0092] Preferably, the electrolyte precursor composition can further contain one or more additives selected from the group consisting of vinylene carbonate (VC), 1,3-propane sultone (PS), and ethylene sulfate (ESa), which can be contained in the electrolyte precursor composition at 0.5 wt% to 5 wt% based on the total weight of the electrolyte precursor composition.

[0093] On the other hand, in one embodiment of the present invention, the electrolyte precursor composition may have a viscosity of 20 cP or less at 25°C, preferably 10 cP to 20 cP, more preferably 10 cP to 15 cP, and the viscosity can be achieved by adjusting the content of the lithium salt. When the viscosity of the precursor composition is 20 cP or less, the impregnation degree of the electrode with respect to the electrolyte precursor composition is appropriately ensured, which is advantageous for the capacity expression of the battery.

[0094] 2) Step of photocuring The method for manufacturing a solid electrolyte-electrode composite according to one embodiment of the present invention includes a step of photocuring an electrode impregnated with the electrolyte precursor composition to form a polymer electrolyte membrane. Specifically, the photocuring is performed by irradiating ultraviolet rays at a intensity of 20 mW / cm 2 ~200 mW / cm 2 , preferably 80 mW / cm 2 ~190 mW / cm 2 , more preferably 100 mW / cm 2 ~180 mW / cm 2 for 20 seconds to 120 seconds.

[0095] By the ultraviolet irradiation, the photocrosslinkable monomers are crosslinked with each other to form a polymer matrix having a three-dimensional network structure, and thereby a polymer electrolyte membrane can be formed on the surface of the electrode.

[0096] The thickness of the polymer electrolyte membrane after the photocuring step may be 10 μm to 50 μm, preferably 15 μm to 45 μm, and more preferably 20 μm to 40 μm. Thereafter, the thickness of the polymer electrolyte membrane does not change even after the thermosetting step.

[0097] 3) Thermosetting step The method for manufacturing a solid electrolyte-electrode composite according to an embodiment of the present invention includes a step of thermosetting the photocured electrode. Specifically, the photocured electrode is stored in an oven set at a temperature of 60°C to 90°C, specifically 60°C to 85°C, and more specifically 70°C to 80°C for 3 hours to 10 hours.

[0098] The electrolyte precursor composition remaining inside the electrode without polymerizing after the photocuring can be completely polymerized by the thermosetting.

[0099] On the other hand, the thickness of the electrode may be 50 μm to 150 μm. When only photocuring is performed as in the prior art, it is difficult for ultraviolet rays to penetrate an electrode with a thickness of 50 μm or more, so complete curing is difficult. However, in the case of the present invention, since both photocuring and thermosetting are applied, there is an advantage that complete curing, that is, 100% polymerization without remaining monomers, is possible even at such a thickness.

[0100] After the thermosetting step, the thickness of the composite of the solid electrolyte and the electrode may be 60 μm to 200 μm, preferably 80 μm to 200 μm, and more preferably 100 μm to 200 μm. The thickness can be measured using a thickness measuring instrument.

[0101] [All-solid-state battery] Next, the all-solid-state battery according to the present invention will be described.

[0102] The all-solid-state battery according to the present invention includes the solid electrolyte-electrode composite.

[0103] Specifically, the solid electrolyte - electrode composite includes one or more solid electrolyte - positive electrode composites and solid electrolyte - negative electrode composites, and the solid electrolyte - positive electrode composite and the solid electrolyte - negative electrode composite can be alternately laminated.

[0104] For example, as shown in FIG. 3, the all - solid - state battery may be a bipolar cell in which a plurality of solid electrolyte - positive electrode composites and solid electrolyte - negative electrode composites are alternately laminated. The solid electrolyte - positive electrode composite 103 is a composite of a positive electrode 100 including a positive electrode current collector 101 and a positive electrode active material layer 102 formed on the positive electrode current collector and a solid electrolyte 300. On the other hand, the solid electrolyte - negative electrode composite 203 is a composite of a negative electrode 200 including a negative electrode current collector 201 and a negative electrode active material layer 202 formed on the negative electrode current collector and a solid electrolyte 300'. At this time, the meanings of "composite" and "composited" mean, as described above, a state in which the electrode is impregnated with the electrolyte precursor composition and photocured and thermally cured to cause polymerization of the electrolyte inside and on the surface of the electrode.

[0105] As described above, since the solid electrolyte - electrode composite according to the present invention is in a completely cured state, there is an advantage that such a bipolar cell can be realized.

[0106] On the other hand, the all - solid - state battery can be manufactured, for example, by forming a solid electrolyte - electrode composite according to the above - mentioned manufacturing method and then laminating a counter electrode. Specifically, the all - solid - state battery can be manufactured by laminating a composite of a solid electrolyte and a positive electrode with a negative electrode, laminating a composite of a solid electrolyte and a negative electrode with a positive electrode, or laminating a composite of a solid electrolyte and a positive electrode with a composite of a solid electrolyte and a negative electrode.

[0107] The all - solid - state battery manufactured according to the present invention can be used not only as a battery cell for powering small devices but also preferably as a unit cell in medium - sized and large - sized battery modules including a large number of battery cells.

[0108] Hereinafter, the present invention will be specifically described through specific examples.

[0109] <Example> Example 1. (1) Preparation of electrolyte precursor composition An electrolyte precursor composition was prepared by mixing LiPF6, 10 wt% of ETPTA, 0.5 wt% of AIBN, and 0.5 wt% of HMPP into a solvent obtained by mixing ethylene carbonate (EC) and propylene carbonate (PC) at a weight ratio of 5:5. At this time, LiPF6 was adjusted to a concentration of 1 M. Then, using a Brookfield viscometer (DV-II+PRO Viscometer, Brookfield), the viscosity of the prepared composition was measured under the conditions of a temperature of 25 °C, a humidity of 50 RH%, and a frequency of 30 Hz, and the result was 15 cP.

[0110] (2) Preparation of positive electrode Li(Ni 0.8 Co 0.1 Mn 0.1 )O2 as a positive electrode active material, carbon black as a conductive material, and polyvinylidene fluoride as a binder were added at a weight ratio of 97.5:1:1.5 to produce a positive electrode slurry (solid content: 60 wt%). The positive electrode slurry was applied and dried on an aluminum (Al) thin film, which is a positive electrode current collector with a thickness of 15 μm, and then roll press was performed to produce a positive electrode with a thickness of 100 μm.

[0111] (3) Preparation of negative electrode Graphite as a negative electrode active material, SBR-CMC as a binder, and carbon black as a conductive material were added at a weight ratio of 95:3.5:1.5 to water as a solvent to produce a negative electrode slurry (solid content: 60 wt%). The negative electrode slurry was applied and dried on a copper (Cu) thin film, which is a negative electrode current collector with a thickness of 10 μm, and then roll press was performed to produce a negative electrode with a thickness of 140 μm.

[0112] (4) Preparation of solid electrolyte-electrode composite Doctor blading was used to apply cm on the positive electrode and the negative electrode respectively. 2Apply 50 μl of the electrolyte precursor composition per hit, and irradiate with UV of 150 mW / cm 2 for 30 seconds to advance photocuring. Then, the electrode including the photocured polymer electrolyte membrane on the surface was transferred to an oven and thermally cured by storing at 80 °C for 4 hours.

[0113] As a result of confirming the thickness of the completed solid electrolyte and electrode composite using a thickness measuring instrument, the solid electrolyte - positive electrode composite was 130 μm, and the solid electrolyte - negative electrode composite was 170 μm.

[0114] Comparative Example 1. Polyelectrolytes were formed on the surfaces of the positive electrode and the negative electrode in the same process as in Example 1, except that thermal curing did not proceed in (4) of Example 1.

[0115] Comparative Example 2. Polyelectrolytes were formed on the surfaces of the positive electrode and the negative electrode in the same process as in Example 1, except that polypropylene glycol diacrylate was used instead of ETPTA in (1) of Example 1.

[0116] <Experimental Example> Experimental Example 1. Confirmation of Degree of Polymerization For the solid electrolyte - positive electrode composites produced in Example 1, Comparative Example 1, and Comparative Example 2, FTIR spectra as shown in FIGS. 1 and 2 were obtained by FTIR analysis. The FTIR analysis was performed using a Nicolet 6700 FTIR System and a SMART Orbit ATR Accessory (ZnSe) from Thermo Fisher Scientic, in the range of 1,700 -1 ~1,600 cm -1 in the region with a resolution of 1 cm -1 .

[0117] In FIG. 1, in the case of Example 1, 1,700 - 1,600 cm -1In the wavenumber region, a sharp shape appears without a peak. However, in the case of Comparative Example 1, it can be observed that the peak appears multiple times. Also, in FIG. 2, it can be confirmed that the peak also appears multiple times in Comparative Example 2. Thus, it can be confirmed that in Comparative Examples 1 and 2, uncured monomers remain inside the electrodes, while in Example 1, no uncured monomers remain inside the electrodes.

[0118] Experimental Example 2. Performance Evaluation of All-Solid-State Batteries By alternately laminating the solid electrolyte-cathode composite and the solid electrolyte-anode composite manufactured in Example 1 three times as shown in FIG. 3, a bipolar all-solid-state battery in which three unit cells are laminated was manufactured.

[0119] For the manufactured all-solid-state battery, constant current charging was carried out at 25°C with a current of 0.1C until a voltage of 11.4V was reached. After the charged cell had gone through a rest period of about 60 minutes, it was confirmed whether the voltage was maintained well. FIG. 4 is a diagram showing the voltage graph over time during the charge and discharge process. Through FIG. 4, it can be confirmed that at full charge, it is about 11.4V and that three unit cells of the 3.8V class are properly connected in series.

[0120] In Comparative Example 1 as well, an attempt was made to manufacture a bipolar all-solid-state battery in the same way. However, since the polymer electrolyte was not fully cured, the electrolyte leaked out from the electrodes, causing a short circuit and making it impossible to realize a normal bipolar all-solid-state battery.

[0121] Experimental Example 3. Performance Evaluation of All-Solid-State Batteries By laminating the solid electrolyte-cathode composite and the solid electrolyte-anode composite manufactured in Example 1, a bipolar all-solid-state battery composed of one single cell was manufactured.

[0122] For the manufactured all-solid-state battery, constant-current charging was carried out at 25°C with a current of 0.1C until a voltage of 3.8V was reached. After the charged cell had undergone a rest period of about 60 minutes, it was confirmed whether the voltage was maintained well. Figure 5 is a diagram showing the voltage graph over time during the charge and discharge process, and it can be confirmed through Figure 5 that normal charging up to 3.8V was carried out.

[0123] The solid electrolyte - positive electrode composite and the solid electrolyte - negative electrode composite manufactured in Comparative Example 2 were also used to manufacture a bipolar all-solid-state battery in the same manner and an attempt was made to charge it. However, by using a long-chain monomer containing less than 3 acrylate groups, since the complete curing of the polymer electrolyte was not achieved, a partial short circuit between the positive electrode and the negative electrode occurred, and it was confirmed that normal charging was not carried out.

Explanation of Symbols

[0124] 100: Positive electrode 101: Positive electrode current collector 102: Positive electrode active material layer 103: Solid electrolyte - positive electrode composite 200: Negative electrode 201: Negative electrode current collector 202: Negative electrode active material layer 203: Solid electrolyte - negative electrode composite 300, 300’: Solid electrolyte

Claims

1. A solid electrolyte-electrode composite in which no peak appears in the wavenumber range of 1,700 cm －１ to 1,600 cm －１ during Fourier transform infrared spectroscopy.

2. The solid electrolyte-electrode composite has a thickness of 60 μm or more and 200 μm or less. The solid electrolyte-electrode composite according to Claim 1.

3. The electrode is a positive electrode containing a positive electrode active material. The positive electrode active material contains one or more selected from the group consisting of lithium nickel cobalt-based composite oxides, lithium manganese-based composite oxides, and lithium iron phosphate-based composite oxides. The solid electrolyte-electrode composite according to Claim 1.

4. The positive electrode active material contains a lithium nickel cobalt-based composite oxide. The lithium nickel cobalt-based composite oxide has a composition represented by the following Chemical Formula 1. The solid electrolyte-electrode composite according to Claim 3: 【Chemical Formula 1】 Li １＋ｘ (Ni ａ Co ｂ Mn ｃ M ｄ )O ２ In the Chemical Formula 1, M is one or more selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo. 1 + x, a, b, c, and d are molar ratios of independent elements, respectively. -0.2 ≤ x ≤ 0.2, 0.60 ≤ a < 1, 0 < b ≤ 0.30, 0 < c ≤ 0.30, 0 ≤ d ≤ 0.10, and a + b + c + d = 1.

5. The electrode is a negative electrode containing a negative electrode active material. The negative electrode active material is a carbon-based material. The solid electrolyte-electrode composite according to Claim 1.

6. Impregnating the electrode with an electrolyte precursor composition containing a photo-crosslinkable monomer containing three or more acrylate groups, an initiator, a lithium salt, and an organic solvent; Photo-curing the electrode impregnated with the electrolyte precursor composition to form a polymer electrolyte membrane; Thermally curing the electrode on which the polymer electrolyte membrane is formed. A method for manufacturing a solid electrolyte-electrode composite, comprising the steps of:

7. The photo-crosslinkable monomer is one or more selected from the group consisting of ethoxylated trimethylolpropane triacrylate, trimethylolpropane ethoxytriacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and tris(2-hydroxyethyl) isocyanurate triacrylate. The method for manufacturing a solid electrolyte-electrode composite according to Claim 6.

8. The initiator contains a photoinitiator and a thermal initiator, or contains an initiator that reacts to both light and heat. The method for manufacturing a solid electrolyte-electrode composite according to Claim 6.

9. The method for manufacturing a solid electrolyte-electrode composite according to claim 6, wherein the electrolyte precursor composition has a viscosity of 20 cP or less.

10. The method for manufacturing a solid electrolyte-electrode composite according to claim 6, wherein the content of the photocrosslinkable monomer is 1% by weight or more and 30% by weight or less based on the total weight of the electrolyte precursor composition.

11. The method for manufacturing a solid electrolyte-electrode composite according to claim 6, wherein the heat curing step is performed by storing the photocured electrode at 60°C or higher and 90°C or lower for 3 hours or more and 10 hours or less.

12. The method for manufacturing a solid electrolyte-electrode composite according to any one of claims 6 to 11, wherein the boiling point of the organic solvent exceeds the temperature at which the heat curing is performed.

13. An all-solid-state battery comprising the solid electrolyte-electrode composite according to any one of claims 1 to 5.

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