All-solid-state battery and method for preparing same

Abstract

The present invention relates to an all-solid-state battery and a method for preparing the all-solid-state battery. The all-solid-state battery comprises: a negative electrode; a positive electrode; and a solid electrolyte layer positioned between the negative electrode and the positive electrode, wherein the solid electrolyte layer includes a first solid electrolyte layer in contact with the negative electrode and a second solid electrolyte layer in contact with the positive electrode, and the first solid electrolyte layer is an amorphous layer and comprises alcohol.

Description

All-solid-state battery and method for manufacturing the same

[0001] It relates to an all-solid-state battery and a method for manufacturing the same.

[0002] Recently, rapid developments have been made in electronic devices that use batteries, such as cell phones, laptop computers, and electric vehicles.

[0003] With these batteries, the development of all-solid-state batteries is underway. All-solid-state batteries are composed entirely of solid materials, specifically those that utilize solid electrolytes. Because the electrolyte is solid, all-solid-state batteries are structurally robust, reducing the risk of fire or explosion due to leakage from external impacts. Furthermore, they can be shaped into a variety of battery shapes.

[0004] One embodiment provides an all-solid-state battery exhibiting excellent battery performance and safety.

[0005] Another embodiment provides a method for manufacturing the above all-solid-state battery.

[0006] One embodiment provides an all-solid-state battery comprising: a cathode; an anode; and a solid electrolyte layer positioned between the cathode and the anode, wherein the solid electrolyte layer includes a first solid electrolyte layer in contact with the cathode and a second solid electrolyte layer in contact with the anode, and wherein the first solid electrolyte layer is an amorphous layer and includes alcohol.

[0007] Another embodiment provides a method for manufacturing an all-solid-state battery, comprising the steps of forming a first solid electrolyte layer by coating and drying a first solid electrolyte layer composition having a viscosity of 5 cPs to 1000 cPs on a negative electrode; positioning a second solid electrolyte layer and a positive electrode on the first solid electrolyte layer to manufacture a laminate; and pressing the laminate.

[0008] An all-solid-state battery according to one embodiment can exhibit excellent battery characteristics by improving interfacial contact between a negative electrode and a solid electrolyte.

[0009] Figure 1 is a schematic drawing of an all-solid-state battery according to one embodiment.

[0010] Figure 2 is a cross-sectional view schematically showing an all-solid-state battery according to another embodiment.

[0011] Figure 3 is a planar SEM photograph of the first solid electrolyte layer manufactured according to Example 1.

[0012] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention. The present invention is defined solely by the scope of the claims set forth below.

[0013] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0014] “Combination of these” means a mixture, laminate, composite, copolymer, alloy, blend, reaction product, etc. of the components.

[0015] It should be understood that the terms "include," "comprise," or "have" are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0016] Throughout this specification, when it is said that a part "includes" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0017] In addition, the terms "about", "substantially", etc. used throughout this specification are used in the sense of numerical values ​​or near numerical values ​​when manufacturing and material tolerances inherent to the meanings stated are presented, and are used to prevent unscrupulous infringers from unfairly exploiting disclosures that mention exact or absolute values ​​to aid understanding of this specification.

[0018] Throughout this specification, the description of “A and / or B” means “A or B or both.”

[0019] Unless otherwise specified herein, when a part such as a layer, film, region, or plate is said to be “on top of” another part, this includes not only cases where it is “directly on top of” the other part, but also cases where there is another part in between.

[0020] In the present invention, "particle size" or "particle diameter" may be an average particle diameter. In addition, the average particle diameter may be defined as the average particle diameter (D50) based on 50% of the cumulative volume in a particle diameter distribution curve. The particle diameter may be measured by a method widely known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope, a scanning electron microscope, or a field emission scanning electron microscope (FE-SEM). Alternatively, the average particle diameter (D50) may be obtained by measuring with a measuring device that utilizes dynamic light-scattering, performing data analysis to count the number of particles for each particle size range, and calculating from this. Alternatively, the average particle diameter (D50) may be measured using a laser diffraction method. When measuring by laser diffraction, more specifically, after the particles to be measured are dispersed in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasonic waves of about 28 kHz at an output of 60 W, and then the average particle diameter (D50) based on 50% of the particle size distribution in the measuring device can be calculated. Alternatively, the average particle diameter may be obtained by randomly measuring the sizes (diameter or length of the major axis) of about 20 particles in a scanning electron microscope image to obtain a particle size distribution, and taking the diameter (D50) of the particles having a cumulative volume of 50% by volume in the particle size distribution as the average particle diameter.

[0021] "Thickness" may be measured, for example, from photographs taken with an optical microscope such as a scanning electron microscope.

[0022] An all-solid-state battery according to one embodiment includes a cathode; an anode; and a solid electrolyte layer positioned between the cathode and the anode, wherein the solid electrolyte layer includes a first solid electrolyte layer in contact with the cathode and a second solid electrolyte layer in contact with the anode.

[0023] In one embodiment, the cathode comprises a cathode current collector and a cathode coating layer positioned on the current collector, wherein the cathode coating layer can be positioned in contact with the first solid electrolyte layer.

[0024] The first solid electrolyte layer is an amorphous layer, meaning that the solid electrolyte does not have a particle form. More specifically, this refers to a single layer in which solid electrolyte particles are crushed together so that interfaces between particles are not visible. This amorphous layer can be confirmed by the absence of interfaces between particles when measured with an SEM. Since the first solid electrolyte layer has no interfaces between particles, interfacial resistance does not exist, and since voids that may form between particles are reduced, lithium ion conduction can be improved. Furthermore, since there are no interfaces between particles, the growth of lithium dendrites that may occur during battery operation can be effectively inhibited.

[0025] This first solid electrolyte layer may be a dense layer, which may be a layer having practically no pores. For example, a dense layer may mean that the area where pores exist is 5% or less of the total area when measured by SEM. The first solid electrolyte layer may be a dense layer because it is manufactured by coating the first solid electrolyte layer with a first solid electrolyte composition containing alcohol, for example, by wet coating using alcohol. The process for forming the first solid electrolyte layer will be described in detail later.

[0026] In one embodiment, the first solid electrolyte layer comprises alcohol. When the first solid electrolyte layer comprises alcohol, a decrease in ionic conductivity when the solid electrolyte is exposed to the air can be suppressed. The alcohol can be ethanol, propanol, isopropanol, butanol, t-butyl alcohol, or a combination thereof.

[0027] This amorphous layer, and the first solid electrolyte layer containing alcohol, is a dense layer that practically contains almost no pores, and since this first solid electrolyte layer is positioned in contact with the negative electrode, especially in contact with the negative electrode coating layer, the pores are reduced even at the interface between the negative electrode and the first solid electrolyte layer, so that the negative electrode and the first solid electrolyte layer can come into close contact with each other and also come into close contact with each other. Accordingly, when charging and discharging the all-solid-state battery, the lithium ions released from the positive electrode active material can promote the movement toward the negative electrode, and can also move uniformly, thereby improving ionic conductivity. Accordingly, the lithium ions that have moved toward the negative electrode can pass through the negative electrode coating layer and be uniformly precipitated and deposited on the negative electrode current collector. This can suppress the uneven precipitation and deposition of lithium ions, and prevent the problem of lithium dendrites occurring due to lithium ions being deposited on the surface of the negative electrode coating layer without passing through the negative electrode coating layer.

[0028] In addition, if the solid electrolyte layer is not composed of two layers of a first solid electrolyte layer and a second solid electrolyte layer, but is composed of a single layer with an amorphous layer structure and containing alcohol, the ionic conductivity of the solid electrolyte layer may be significantly reduced. On the other hand, if the second solid electrolyte layer in contact with the positive electrode is an amorphous layer and contains alcohol, the solid electrolyte contained in the positive electrode may be dissolved, resulting in a decrease in ionic conductivity and an increase in resistance.

[0029] A first solid electrolyte layer according to one embodiment includes alcohol and a first solid electrolyte, and may further include a binder.

[0030] In the first solid electrolyte layer, the content of the alcohol may be 0.08 wt% to 0.13 wt%, or may be 0.1 wt% to 0.13 wt%, based on 100 wt% of the first solid electrolyte layer. When the content of the alcohol in the first solid electrolyte layer is within the above range, the ionic conductivity can be further improved. The content of the alcohol contained in the first solid electrolyte layer can be measured by thermogravimetric analysis (TGA).

[0031] In the first solid electrolyte layer, the content of the first solid electrolyte may be 99.87 wt% to 99.92 wt%, or may be 99.87 wt% to 99.9 wt%, based on 100 wt% of the first solid electrolyte layer. When the content of the first solid electrolyte is within the above range, the interfacial contact between the solid electrolyte layer and the negative electrode can be further improved, for example, the adhesive properties can be improved.

[0032] When the first solid electrolyte layer further includes a binder, the content of the binder may be 0.1 wt% to 24.87 wt%, or 0.5 wt% to 23.87 wt%, based on 100 wt% of the first solid electrolyte layer. When the content of the binder is within the above range, sufficient adhesive strength can be provided without increasing resistance.

[0033] When the first solid electrolyte layer further includes a binder, the content of the first solid electrolyte may be 75 wt% to 99 wt% or 76 wt% to 99 wt% with respect to 100 wt% of the first solid electrolyte layer.

[0034] The second solid electrolyte layer includes a second solid electrolyte and may further include a binder. When the second solid electrolyte layer further includes a binder, the content of the second solid electrolyte may be 80 wt% to 99.9 wt%, 85 wt% to 99.5 wt%, or 99 wt% to 90 wt%, with respect to 100 wt% of the second solid electrolyte layer. The content of the binder may be 0.1 wt% to 20 wt%, 0.5 wt% to 15 wt%, or 1 wt% to 10 wt%, with respect to 100 wt% of the second solid electrolyte layer.

[0035] When the content of the second solid electrolyte in the second solid electrolyte layer satisfies the above range, the ionic conductivity can be further improved, and the interface contact between the solid electrolyte layer and the positive electrode can be further improved, for example, the adhesive properties can be improved.

[0036] In one embodiment, the thickness of the first solid electrolyte layer may be 10 μm to 200 μm, or 20 μm to 100 μm. When the thickness of the first solid electrolyte layer is within the above range, lithium dendrite growth can be suppressed.

[0037] The thickness of the second solid electrolyte layer may be 10 μm to 200 μm, or 20 μm to 100 μm. When the thickness of the second solid electrolyte layer is within the above range, lithium ion conductivity may be increased.

[0038] In one embodiment, the second solid electrolyte included in the second solid electrolyte layer may be in the form of particles.

[0039] In one embodiment, the second solid electrolyte may include a counter solid electrolyte, for example counter solid electrolyte particles. The average particle size of the counter solid electrolyte particles may be greater than 0.1 μm, for example, 0.5 μm to 20 μm, or 1 μm to 10 μm. When the second solid electrolyte is a counter solid electrolyte particle having the above size, voids within the solid electrolyte layer can be minimized.

[0040] The above first solid electrolyte may be a sulfide-based solid electrolyte.

[0041] The second solid electrolyte may be an inorganic solid electrolyte such as a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a halide-based solid electrolyte, or a solid polymer electrolyte. When the second solid electrolyte is a sulfide-based solid electrolyte, the first and second solid electrolytes may be the same sulfide-based solid electrolyte or different sulfide-based solid electrolytes.

[0042] The above sulfide-based solid electrolyte is Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element, for example, I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m and n are integers greater than or equal to 0 and less than or equal to 12, respectively, and Z is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are integers greater than or equal to 0 and less than or equal to 12, respectively; M is one of P, Si, Ge, B, Al, Ga In), Li a M b P c S dA e (a, b, c, d and e are each integers greater than or equal to 0 and less than or equal to 12, M is Ge, Sn, Si or a combination thereof, and A is one of F, Cl, Br, or I). The sulfide-based solid electrolyte may be, for example, Li 7-x PS 6-x F x (0≤x≤2), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2) or Li 7-x PS 6-x I x (0≤x≤2) can be. Also, specifically, Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Cl, Li6PS5I, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 It could be the back.

[0043] In one embodiment, the sulfide-based solid electrolyte may be an argyrodite-type sulfide-based solid electrolyte. The argyrodite-type sulfide-based solid electrolyte may be, for example, Li a M b P c S d A e (a, b, c, d, and e are all 0 or greater and 12 or less, M is Ge, Sn, Si, or a combination thereof, and A is one of F, Cl, Br, or I).

[0044] As specific examples, Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br0.8 , Li6PS5I, Li 5.75 PS 4.75 Cl 1.25 , (Li 5.69 Cu 0.06 )PS 4.75 Cl 1.25 , (Li 5.72 Cu 0.03 )PS 4.75 Cl 1.25 , (Li 5.69 Cu 0.06 )P(S 4.70 (SO4) 0.05 )Cl 1.25 , (Li 5.69 Cu 0.06 )P(S 4.60 (SO4) 0.15 )Cl 1.25 , (Li 5.72 Cu 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 , (Li 5.72 Na 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 , Li 5.75 P(S 4.725 (SO4) 0.025 )Cl 1.25 , or combinations thereof, but are not limited thereto.

[0045] The sulfide-based solid electrolyte may be amorphous, crystalline, or a mixture thereof. For example, the sulfide-based solid electrolyte may be obtained by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10, or in a molar ratio of 50:50 to 80:20. Within the above mixing ratio range, a sulfide-based solid electrolyte having excellent ionic conductivity can be produced. Here, the ionic conductivity can be further improved by further including other components such as SiS2, GeS2, and B2S3.

[0046] Methods for mixing sulfur-containing raw materials for manufacturing sulfide-based solid electrolytes include mechanical milling and solution methods. Mechanical milling involves placing the starting raw materials in a reactor and vigorously stirring them with a ball mill, thereby finely agitating the starting raw materials and mixing them. Using the solution method, the starting raw materials are mixed in a solvent to obtain a solid electrolyte as a precipitate. Furthermore, heat treatment after mixing can solidify the crystals of the solid electrolyte and improve ionic conductivity. For example, a sulfide-based solid electrolyte can be manufactured by mixing sulfur-containing raw materials and heat-treating them twice or more, in which case a sulfide-based solid electrolyte with high ionic conductivity and robustness can be manufactured.

[0047] Of course, a commercially available solid electrolyte can be used as the sulfide-based solid electrolyte.

[0048] The above oxide-based solid electrolyte is, for example, Li 1+x Ti 2-x Al(PO4)3(LTAP)(0≤x≤4), Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0≤x<1, 0≤y<1), Pb(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0 <x<2, 0<y<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-xSi y P 3-y O 12 (0≤x≤1, 0≤y≤1), lithium lanthanum titanate (Li x La y TiO3, 0 <x<2, 0<y<3), Li2O, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2계 세라믹스, 가넷(Garnet)계 세라믹스 Li 3+x La3M2O 12 (M= Te, Nb, or Zr, x is an integer from 1 to 10), or a mixture thereof.

[0049] The above solid polymer electrolytes include, for example, polyethylene oxide, poly(diallyldimethylammonium)trifluoromethanesulfonyl imide (poly(diallyldimethylammonium)TFSI), Cu3N, Li3N, LiPON, and Li3PO. 4· Li2S · SiS2, Li2S · GeS 2· Ga2S3, Li2O · 11Al2O3, Na2O · 11Al2O3, (Na,Li) 1+x Ti 2-x Al x (PO4)3(0.1≤x≤0.9), Li 1+x Hf 2-x Al x (PO4)3(0.1≤x≤0.9), Na3Zr2Si2PO 12 , Li3Zr2Si2PO 12 , Na5ZrP3O 12 , Na5TiP3O 12 , Na3Fe2P3O 12 , Na4NbP3O 12 , Na-Silicates, Li 0.3 La 0.5 TiO3, Na5MSi4O 12 (M is a rare earth element such as Nd, Gd, Dy) Li5ZrP3O 12 , Li5TiP3O 12 , Li3Fe2P3O 12, Li4NbP3O 12 , Li 1+x (M,Al,Ga) x (Ge 1-y Ti y ) 2-x (PO4)3(0≤x≤0.8, 0≤y≤1.0, M is Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm or Yb), Li 1+x+y Q x Ti 2-x Si y P 3-y O 12 (0 <x≤0.4, 0<y≤0.6, Q 는 Al 또는 Ga), Li6BaLa2Ta2O 12 , Li7La3Zr2O 12 , Li5La3Nb2O 12 , Li5La3M2O 12 (M is Nb, Ta) and Li 7+x A x La 3-x Zr2O 12 (0 <x<3, A는 Zn) 중에서 선택된 하나 이상을 포함할 수 있다.

[0050] The above halide-based solid electrolyte may include a Li element, an M element (M is a metal other than Li), and an X element (X is a halogen). As X, for example, F, Cl, Br, and I may be mentioned. In particular, in the halide-based solid electrolyte, at least one of Br and Cl is suitable as X. In addition, as the M, for example, a metal element such as Sc, Y, B, Al, Ga, or In may be mentioned.

[0051] The composition of the above halide-based solid electrolyte is not particularly limited, but Li 6-3a M a Br b Cl c(In the formula, M is a metal other than Li, and 0 <a<2, 0≤b≤6, 0≤c≤6, b+c=6)로 표현될 수 있다. 이때, 상기 a는 0.75 이상일 수 있고, 1 이상일 수 있고, a는, 1.5 이하일 수 있다. 상기 b는 1 이상일 수 있고, 2 이상일 수 있다. 또한, 상기 c는, 3 이상일 수 있고, 4 이상일 수도 있다. 상기 할라이드계 고체 전해질의 구체적인 예로는 Li3YBr6, Li3YCl6또는 Li3YBr2Cl4를 들 수 있다.

[0052] The binder included in the first and second solid electrolyte layers may be, but is not limited to, styrene butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, an acrylate polymer, or a combination thereof, and any binder used in the relevant technical field may be used. The acrylate polymer may be butyl acrylate, polyacrylate, polymethacrylate, or a combination thereof.

[0053] The first solid electrolyte layer and the second solid electrolyte layer may further include an alkali metal salt, an ionic liquid, and / or a conductive polymer.

[0054] The alkali metal salt may be, for example, a lithium salt. The content of the lithium salt in the solid electrolyte layer may be 1 M or more, for example, 1 M to 4 M. In this case, the lithium salt may improve ion conductivity by enhancing the lithium ion mobility of the first and second solid electrolyte layers.

[0055] The above lithium salts include, for example, LiSCN, LiN(CN)2, Li(CF3SO2)3C, LiC4F9SO3, LiN(SO2CF2CF3)2, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiBF4, LiBF3(C2F5), lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate (LIODFB), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(trifluoro methanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, It may include LiN(SO2F)2), LiCF3SO3, LiAsF6, LiSbF6, LiClO4 or mixtures thereof.

[0056] In addition, the lithium salt may be an imide-based one, and for example, the imide-based lithium salt may include lithium bis(trifluoro methanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2). The lithium salt may maintain or improve ionic conductivity by appropriately maintaining chemical reactivity with an ionic liquid.

[0057] The above ionic liquid has a melting point below room temperature and is a salt or room-temperature molten salt that is liquid at room temperature and consists only of ions.

[0058] The above ionic liquid comprises a) one or more cations selected from ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, triazolium, and mixtures thereof, and b) BF4. - , PF6 - , AsF6 - , SbF6 - , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 - , CF3CO2 - , Cl - , Br - , I - , BF4 - , SO4 - , CF3SO3 - , (FSO2)2N - , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - , and (CF3SO2)2N - It may be a compound containing one or more anions selected from among.

[0059] The ionic liquid may be at least one selected from the group consisting of, for example, N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidinium bis(3-trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide.

[0060] The weight ratio of the solid electrolyte and the ionic liquid in the first and second solid electrolyte layers may be 0.1:99.9 to 90:10, for example, 10:90 to 90:10, 20:80 to 90:10, 30:70 to 90:10, 40:60 to 90:10, or 50:50 to 90:10. A solid electrolyte layer satisfying the above range can maintain or improve ionic conductivity by improving the electrochemical contact area with the electrode. Accordingly, the energy density, discharge capacity, rate characteristics, etc. of the all-solid-state secondary battery can be improved.

[0061] According to one embodiment, a cathode includes a cathode current collector and a cathode coating layer positioned on the cathode current collector.

[0062] In one embodiment, the negative electrode coating layer refers to a layer that helps lithium ions released from the positive electrode active material during charge / discharge of an all-solid-state battery to move toward the negative electrode and be deposited on the surface of the current collector. That is, a lithium deposition layer is formed between the current collector and the negative electrode coating layer due to the deposition of lithium ions, and the lithium deposition layer functions as a negative electrode active material. Such a negative electrode is generally referred to as a deposition-type negative electrode. The metal and amorphous carbon included in the negative electrode coating layer do not function as a negative electrode active material that directly participates in the charge / discharge reaction. Such a deposition-type negative electrode refers to a negative electrode that does not include a negative electrode active material when the battery is assembled, but in which the lithium deposition layer functions as a negative electrode active material.

[0063] The above-described negative electrode coating layer may include a metal acting as a catalyst, a carbon-based material, and a binder, and may be formed of, for example, a metal acting as a catalyst, a carbon-based material, and a binder. In this way, the negative electrode coating layer according to one embodiment does not include a solid electrolyte, and since it does not include a solid electrolyte, a lithium deposition layer formed on a current collector during charging of an all-solid-state battery may be formed more effectively.

[0064] In the above cathode coating layer, for example, a metal may be supported on a carbon-based material, or a metal and a carbon-based material may be present in a mixture.

[0065] The carbonaceous material may be, for example, crystalline carbon, amorphous carbon, or a combination thereof, and may be amorphous carbon. The crystalline carbon may be, for example, natural graphite, artificial graphite, mesophase carbon microbeads, carbon nanotubes, graphene, or a combination thereof. The crystalline carbon may be in the form of amorphous, plate-like, flake-like, spherical, or fibrous particles. The amorphous carbon may be, for example, carbon black, acetylene black, Denka black, Ketjen black, furnace black, activated carbon, graphene, or a combination thereof. An example of the carbon black is Super P (Timcal). The amorphous carbon is not limited thereto, and any material classified as amorphous carbon in the relevant field may be used.

[0066] In one embodiment, the carbonaceous material may be a single particle, or may be an assembly having a secondary particle form in which primary particles are assembled. When the carbonaceous material is a single particle, the size of the carbonaceous material may be a nano-size with an average particle diameter of 100 nm or less, for example, 10 nm to 100 nm.

[0067] Additionally, when the carbon-based material is an assembly, the particle size of the primary particles may be 20 nm to 100 nm, and the particle size of the secondary particles may be 1 μm to 20 μm.

[0068] In one embodiment, the particle size of the primary particles may be 20 nm or more, 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, 70 nm or more, 80 nm or more, or 90 nm or more, and may be 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, or 30 nm or less.

[0069] In one embodiment, the particle size of the secondary particles may be 1 µm or more, 3 µm or more, 5 µm or more, 7 µm or more, 10 µm or more, or 15 µm or more, and may be 20 µm or less, 15 µm or less, 10 µm or less, 7 µm or less, 5 µm or less, or 3 µm or less.

[0070] The shape of the primary particles may be spherical, elliptical, plate-shaped, or a combination thereof, and in one embodiment, the shape of the primary particles may be spherical, elliptical, or a combination thereof.

[0071] The above metal may be Ag, Au, Sn, Zn, Al, Mg, Ge, Cu, In, Ni, Bi, Pt, Pd or a combination thereof. As the cathode coating layer includes the above metal, the electrical conductivity of the cathode can be further improved.

[0072] The metal may be a nanoparticle, and the size of the metal nanoparticle may be, for example, an average size of 5 nm to 80 nm, but a nanometer size may be suitably used. By using the metal nanoparticle having such a nano size, the battery characteristics (e.g., life characteristics) of the all-solid-state battery can be improved. If the metal particle size increases to the micrometer level, the uniformity of the metal particles in the negative electrode coating layer decreases, so that the current density in a specific region increases and the cycle life characteristics may deteriorate, which is not suitable.

[0073] In one embodiment, the content of the metal may be 3 wt% to 30 wt%, 4 wt% to 25 wt%, 5 wt% to 20 wt%, or 5 wt% to 15 wt% relative to 100 wt% of the total weight of the cathode coating layer.

[0074] Additionally, the carbon-based material may be present in an amount of 70 wt% to 97 wt%, 75 wt% to 96 wt%, 80 wt% to 95 wt%, or 85 wt% to 95 wt% relative to 100 wt% of the total weight of the cathode coating layer.

[0075] The above cathode coating layer may further include a binder. The binder may be a non-aqueous binder.

[0076] The non-aqueous binder may include, for example, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyethylene oxide, ethylene propylene copolymer, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, polyacrylate, or combinations thereof.

[0077] The binder may be present in an amount of 1 wt% to 15 wt% relative to 100 wt% of the total negative electrode coating layer. For example, the binder may be present in an amount of 1 wt% or more, 2 wt% or more, 3 wt% or more, 4 wt% or more, 5 wt% or more, 6 wt% or more, 7 wt% or more, 8 wt% or more, 9 wt% or more, 10 wt% or more, 11 wt% or more, 12 wt% or more, 13 wt% or more, or 14 wt% or more, and 15 wt% or less, 14 wt% or less, 13 wt% or less, 12 wt% or less, 11 wt% or less, 10 wt% or less, 9 wt% or less, 8 wt% or less, 7 wt% or less, 6 wt% or less, 5 wt% or less, 4 wt% or less, 3 wt% or less, or 2 wt% or less relative to 100 wt% of the total negative electrode coating layer.

[0078] When the above binder is included in the negative electrode coating layer of the all-solid-state battery in the above content range, the electrical resistance and adhesive strength can be improved, thereby improving the characteristics (battery capacity and output characteristics) of the all-solid-state battery.

[0079] The thickness of the cathode coating layer may be 1 µm to 20 µm. For example, the thickness of the cathode coating layer may be 1 µm or more, 3 µm or more, 5 µm or more, 20 µm or less, 18 µm or less, 16 µm or less, 14 µm or less, 12 µm or less, or 10 µm or less.

[0080] The current collector may be, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li) or an alloy thereof, and may be in the form of a foil or sheet. The thickness of the negative electrode current collector may be 1 μm to 20 μm, 5 μm to 15 μm, or 7 μm to 10 μm.

[0081] The current collector may be formed of the metal as a substrate and may further include a thin film formed on the substrate. The thin film may include an element capable of forming an alloy with lithium, and may be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, or a combination thereof, but is not limited thereto, and any element capable of forming an alloy with lithium in the art may be used. When the current collector further includes a thin film, when the lithium-containing layer is formed by precipitation during charging, a more planarized lithium-containing layer may be formed, thereby further improving the cycle life of the all-solid-state battery.

[0082] The thickness of the above thin film may be 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. When the thin film thickness is within the above range, the cycle life characteristics can be further improved.

[0083] According to one embodiment, the negative electrode may further include a lithium-containing layer formed during initial charging after battery manufacturing, between the current collector and the negative electrode coating layer. The thickness of the lithium-containing layer may be 1 µm to 1000 µm, 1 µm to 500 µm, 1 µm to 200 µm, 1 µm to 150 µm, 1 µm to 100 µm, or 1 µm to 50 µm. When the thickness of the lithium-containing layer is within the above range, the lithium storage function may be appropriately performed, and there may be an advantage of further improving the lifespan.

[0084] The lithium-containing layer can be formed when lithium ions are released from the positive electrode active material during charging after the battery is manufactured, pass through the solid electrolyte, and move toward the negative electrode, resulting in lithium being precipitated and deposited on the negative electrode current collector.

[0085] The above charging process may be a chemical reaction process performed once to three times at 0.05C to 1C at about 25°C to 50°C. When lithium is precipitated and deposited to form a lithium-containing layer, the lithium contained in the lithium-containing layer is ionized and moves toward the positive electrode during discharge, so that the lithium can be used as an anode active material.

[0086] In one embodiment, since the lithium-containing layer is positioned between the current collector and the negative electrode coating layer, the negative electrode coating layer can serve as a protective layer for the lithium-containing layer, thereby inhibiting the precipitation and growth of lithium dendrites. This can suppress short-circuiting and capacity degradation of the all-solid-state battery, and consequently improve the cycle life of the all-solid-state battery.

[0087] According to one embodiment, a positive electrode of an all-solid-state battery includes a positive electrode current collector and a positive electrode active material layer positioned on one surface of the positive electrode current collector.

[0088] The above-described positive electrode active material layer may include a positive electrode active material. The positive electrode active material may be a positive electrode active material capable of reversibly absorbing and releasing lithium ions. For example, the positive electrode active material may use at least one of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof. Specific examples of the positive electrode active material include Li a A 1-b B 1 b D 1 2(0.90≤a≤1.8, 0≤b≤0.5); Li a E 1-b B 1 b O 2-c D 1 c (0.90≤a ≤1.8, 0 ≤b≤0.5, 0≤c≤0.5); Li a E 2-b B 1 b O 4-c D 1 c (0.90≤a≤1.8, 0≤b≤0.5, 0≤ c≤05); Li a Ni 1-b-c Co b B 1 c D 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α≤2); Li a Ni 1-b-c Co b B 1 c O 2-α F 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Co b B 1 c O 2-α F 1 2(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mnb B 1 c D 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α≤2); The a Nor 1-b-c Mn b B 1 c O 2-α F 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); The a Nor 1-b-c Mn b B 1 c O 2-α F 1 2(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); The a Nor b E c G d O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1); The a Nor b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); The a NiG b O2( 0.90≤a≤1.8, 0.001≤b≤0.1); The a CoG b O2(0.90≤a≤1.8, 0.001≤b≤ 0.1); The a MnG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); The a Mn2G b O4(0.90≤a≤1.8, 0.001≤b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiI 1 O2; LiNiVO4; The (3-f) J2(PO4)3(0 ≤f≤2); The (3-f)Fe2(PO4)3(0≤f≤2); or LiFePO4.

[0089] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; B 1 is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof; D 1 is O, F, S, P, or a combination thereof, and E is Co, Mn, or a combination thereof; F 1 is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I 1 is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof; L 1 is Mn, Al or a combination thereof.

[0090] According to one implementation example, LiNi is used as the positive electrode active material. x Co y Al z O2(NCA), LiNi x Co y Mn z O2(NCM)(but, 0 <x<1, 0<y<1, 0<z<1, x+y+z=1) 등의 삼성분계 리튬 전이 금속 산화물을 들 수 있다.

[0091] Of course, it is also possible to use a compound having a coating layer on the surface of the compound, or it is also possible to use a mixture of the compound and a compound having a coating layer. The coating layer may include at least one coating element compound selected from the group consisting of an oxide of the coating element, a hydroxide of the coating element, an oxyhydroxide of the coating element, an oxycarbonate of the coating element, and a hydroxycarbonate of the coating element. The compounds forming these coating layers may be amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer forming process may use any coating method as long as it can coat the compound with these elements in a method that does not adversely affect the properties of the positive electrode active material (for example, spray coating, dipping, etc.), and since this is well understood by those working in the relevant field, a detailed description thereof will be omitted.

[0092] In addition, as the above coating layer, any known coating layer of the positive electrode active material of an all-solid-state battery can be applied, and examples thereof include Li2O-ZrO2 (LZO).

[0093] Furthermore, when the cathode active material is a ternary compound containing nickel, cobalt, and manganese, or nickel, cobalt, and aluminum, the capacity density of the all-solid-state battery can be further improved and metal dissolution from the cathode active material can be further reduced in a charged state. Consequently, the all-solid-state battery can exhibit improved long-term reliability and cycle performance in a charged state.

[0094] Here, examples of the shape of the positive electrode active material include spherical, elliptical, and other particle shapes. Furthermore, the average particle diameter of the positive electrode active material is not particularly limited, and may be within the range applicable to positive electrode active materials for existing all-solid-state secondary batteries. Furthermore, the content of the positive electrode active material in the positive electrode active material layer is also not particularly limited, and may be within the range applicable to positive electrode layers for existing all-solid-state secondary batteries.

[0095] The positive electrode active material layer may additionally include a solid electrolyte. The solid electrolyte included in the positive electrode active material layer may be the same as or different from the solid electrolyte included in the first and second solid electrolyte layers. The solid electrolyte may be included in an amount of 10 wt% to 30 wt% relative to the total 100 wt% of the positive electrode active material layer.

[0096] The above positive electrode current collector may include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li) or an alloy thereof, and may be in the form of a foil or sheet.

[0097] The above positive electrode active material layer may further include a binder and / or a conductive material.

[0098] The above binder may include, but is not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc.

[0099] The above binder may be included in an amount of 0.1 wt% to 5 wt%, or 0.1 wt% to 3 wt%, based on 100 wt% of the total weight of the positive electrode active material layer for the all-solid-state battery. Within the above content range, the binder can sufficiently exhibit adhesive ability without deteriorating battery performance.

[0100] The conductive material is used to provide conductivity to the electrode, and any material that does not cause chemical changes and is electronically conductive can be used in the battery. Examples of the conductive material include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and carbon nanotubes; metal-based materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber; conductive polymers such as polyphenylene derivatives; or conductive materials including mixtures thereof.

[0101] The conductive material may be included in an amount of 0.1 wt% to 5 wt%, or 0.1 wt% to 3 wt%, based on 100 wt% of the total weight of the positive electrode active material layer for the all-solid-state battery. Within the above content range, the conductive material may improve electrical conductivity without degrading battery performance.

[0102] The thickness of the positive electrode active material layer may be 90 μm to 200 μm. For example, the thickness of the positive electrode active material layer may be 90 μm or more, 100 μm or more, 110 μm or more, 120 μm or more, 130 μm or more, 140 μm or more, 150 μm or more, 160 μm or more, 170 μm or more, 180 μm or more, or 190 μm or more, and may be 200 μm or less, 190 μm or less, 180 μm or less, 170 μm or less, 160 μm or less, 150 μm or less, 140 μm or less, 130 μm or less, 120 μm or less, or 110 μm or less.

[0103] An all-solid-state battery according to one embodiment may further include a buffering material to cushion changes in thickness that occur during charging and discharging. The buffering material may be positioned between the negative electrode and the case, and in the case of a battery in which one or more electrode assemblies are stacked, the buffering material may be positioned between different electrode assemblies.

[0104] The above-mentioned cushioning material may be a material having an elastic recovery rate of 50% or more and an insulating function, and specifically, may be silicone rubber, acrylic rubber, fluorine rubber, nylon, synthetic rubber, or a combination thereof. The above-mentioned cushioning material may be in the form of a polymer sheet.

[0105] <Method for manufacturing an all-solid-state battery>

[0106] According to one embodiment, an all-solid-state battery can be manufactured by a process of forming a first solid electrolyte layer by coating and drying a first solid electrolyte layer composition having a viscosity of 5 cPs to 1000 cPs on a negative electrode, positioning a second solid electrolyte layer and a positive electrode on the first solid electrolyte layer to manufacture a laminate, and pressurizing the laminate. Each process will be described in detail below.

[0107] First, a first solid electrolyte layer is formed by coating and drying a first solid electrolyte layer composition having a viscosity of 5 cPs to 1000 cPs on the negative electrode. The negative electrode includes a negative current collector and a negative electrode coating layer positioned on the negative current collector. Accordingly, the process can be performed by coating and drying the first solid electrolyte layer composition on the negative electrode coating layer.

[0108] The viscosity of the first solid electrolyte layer composition may be a viscosity value at room temperature (20°C to 25°C), for example, the viscosity may be 10°C to 900°C, or 100°C to 800°C. If the viscosity of the first solid electrolyte layer composition is outside the above range, that is, if the viscosity is lower than the above range, the first solid electrolyte layer composition is not suitable for being completely impregnated into the negative electrode, particularly the negative electrode coating layer. In addition, if the viscosity is higher than the above range, the coating process cannot be performed, which is not suitable.

[0109] The first solid electrolyte layer composition may include a first solid electrolyte and an alcohol. In addition, the first solid electrolyte layer composition may further include a binder. The first solid electrolyte, alcohol, and binder are as described above.

[0110] In the first solid electrolyte layer composition, the content of the first solid electrolyte and the alcohol, optionally the binder, can be appropriately adjusted so that the viscosity of the first solid electrolyte layer composition satisfies the above range. For example, the content of the first solid electrolyte may be 1 wt% to 20 wt%, 2 wt% to 15 wt%, or 5 wt% to 10 wt%, based on 100 wt% of the first solid electrolyte layer composition. The total content of the alcohol and the binder may be 80 wt% to 99 wt%, 85 wt% to 98 wt%, or 90 wt% to 95 wt%. Within the above content range, the mixing ratio of the alcohol and the binder may be 0.1:99.9 to 4:96 by weight, or 0.1:99.9 to 3.5:96.5 by weight.

[0111] The above drying process can be carried out at 50°C to 250°C, and can also be carried out at 80°C to 200°C. Depending on the drying process, alcohol can be removed by volatilization from the first solid electrolyte layer composition, and if the drying process is carried out in the above temperature range, alcohol can remain in the formed first solid electrolyte layer, for example, 0.08 wt% to 0.13 wt% can remain with respect to 100 wt% of the first solid electrolyte layer, which is suitable.

[0112] Next, a laminate is manufactured by sequentially positioning a second solid electrolyte layer and an anode on the first solid electrolyte layer.

[0113] The second solid electrolyte layer can be formed by adding a second solid electrolyte to a binder solution, coating the same on a base film, and drying the same. The solvent of the binder solution may be isobutylyl isobutylate, xylene, toluene, benzene, hexane, or a combination thereof. In addition, the binder in the binder solution is as described above. Since the process for forming the second solid electrolyte layer is widely known in the art, a detailed description thereof will be omitted herein.

[0114] Next, the laminate is pressed. The pressing process can be performed at a temperature ranging from 25°C to 90°C. In addition, the pressing process can be performed by pressing at a pressure of 550 MPa or less, for example, 500 MPa or less, for example, in a range from 1 MPa to 500 MPa. The pressing time can vary depending on the temperature and pressure, and can be, for example, less than 30 minutes. The pressing process can be, for example, isostatic pressing, roll pressing, plate pressing, or warm isostatic pressing (WIP).

[0115] The above-mentioned all-solid-state secondary battery may be a unit cell having a structure of positive electrode / solid electrolyte layer / negative electrode, a bi-cell having a structure of positive electrode / solid electrolyte layer / negative electrode / solid electrolyte layer / positive electrode, or a laminated battery in which the structure of the unit cell is repeated.

[0116] The shape of the above-mentioned all-solid-state secondary battery is not particularly limited, and may be, for example, coin-shaped, button-shaped, sheet-shaped, stacked, cylindrical, flat, etc. In addition, the above-mentioned all-solid-state secondary battery can be applied to large-scale batteries used in electric vehicles, etc. For example, the above-mentioned all-solid-state secondary battery can be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). In addition, it can be used in fields requiring a large amount of power storage, and for example, it can be used in electric bicycles or power tools, etc. In addition, the above-mentioned all-solid-state secondary battery can be used in various fields such as portable electronic devices.

[0117] FIG. 1 is a cross-sectional view of an all-solid-state battery according to one embodiment. Referring to FIG. 1, the all-solid-state battery (100) may have a structure in which an electrode assembly in which a negative electrode (400) including a negative electrode collector (401) and a negative electrode coating layer (403), a solid electrolyte layer (300) including a first solid electrolyte layer (301) and a second solid electrolyte layer (303), and a positive electrode (200) including a positive electrode active material layer (203) and a positive electrode collector (201) are laminated is housed in a case such as a pouch. The all-solid-state battery (100) may further include an elastic layer (500) on the outer side of at least one of the positive electrode (200) and the negative electrode (400). Although FIG. 1 illustrates one electrode assembly including the negative electrode (400), the solid electrolyte layer (300), and the positive electrode (200), an all-solid-state battery may be manufactured by laminating two or more electrode assemblies. For example, they can be stacked in numbers of 2 to 100, 3 to 50, 4 to 20, etc.

[0118] Fig. 2 schematically illustrates an all-solid-state battery according to another embodiment. The all-solid-state battery (100) illustrated in Fig. 2 includes a positive electrode (200) including a positive electrode current collector (201) and a positive electrode active material layer (203), a negative electrode (400') including a negative electrode current collector (401'), a negative electrode coating layer (403'), and a first solid electrolyte layer (301) and a second solid electrolyte layer (303) including a solid electrolyte (300), a battery case (500) containing them, and a lithium precipitation layer (405') between the negative electrode current collector (401') and the negative electrode coating layer (403'). When the all-solid-state battery is charged, lithium ions can be released from the positive electrode active material and deposited on the negative electrode current collector (401') to form this lithium precipitation layer.

[0119] Hereinafter, examples and comparative examples of the present invention will be described. The following examples are merely exemplary of the present invention, and the present invention is not limited to the following examples.

[0120] (Example 1)

[0121] (1) Manufacturing of cathode

[0122] A cathode coating layer slurry was prepared by mixing 92 wt% of carbon black having an average particle diameter (D50) of 30 nm, 3 wt% of Ag having an average particle diameter (D50) of 60 nm, 2 wt% of carboxymethylcellulose, and 3 wt% of styrene-butadiene rubber in water.

[0123] The cathode coating layer slurry was coated on a stainless steel foil current collector having a thickness of 10 μm, and then vacuum-dried at 80°C to manufacture a cathode. In the manufactured cathode, the thickness of the cathode coating layer was 2 μm.

[0124] (2) Manufacturing of solid electrolyte layer

[0125] A solid electrolyte of argyrodite type, Li6PS5Cl, butyl acrylate and ethanol were mixed. At this time, the mixing ratio of the solid electrolyte, binder and ethanol was set to 10:0.1:89.9 by weight.

[0126] The above mixing process was performed using a sinky mixer. 2 mm zirconia balls were added to the obtained mixture and stirred again using the sinky mixer to produce a first solid polymer layer slurry having a viscosity of 500 cPs at room temperature (25°C).

[0127] The first solid polymer layer slurry was coated on the cathode coating layer and dried at 200°C to produce a first solid electrolyte layer having a thickness of 30 μm.

[0128] An isobutyryl isobutylate binder solution (solid content: 50 wt%) containing an acrylate polymer, butyl acrylate, was added to an argyrodite-type solid electrolyte Li6PS5Cl having an average particle diameter (D50) of 3 μm and mixed. At this time, the mixing ratio of the solid electrolyte and the binder was set to a weight ratio of 98.7:1.3.

[0129] The above mixing process was performed using a sinky mixer. 2 mm zirconia balls were added to the resulting mixture and stirred again using the sinky mixer to produce a slurry. The slurry was cast onto a polytetrafluoroethylene film and dried at room temperature to produce a second solid electrolyte layer with a thickness of 100 μm.

[0130] (3) Manufacturing of the anode

[0131] Cathode active material (LiNi) 0.9 Mn 0.05 Co 0.05 A mixture was prepared by mixing O2), argyrodite-type solid electrolyte Li6PS5Cl, conductive carbon nanofibers, and binder polytetrafluoroethylene in a weight ratio of 85:15:3:1.5.

[0132] The prepared mixture was coated on an aluminum foil current collector and then vacuum-dried at 45°C to prepare a positive electrode including a 160 μm thick positive electrode active material layer and a 10 μm thick current collector.

[0133] (4) Manufacturing of all-solid-state full cells

[0134] The manufactured negative electrode, solid electrolyte layer, and positive electrode were sequentially laminated, and a pressure of 16 MPa was applied to manufacture an all-solid-state battery. At this time, the second solid electrolyte layer was positioned so as to be in contact with the positive electrode.

[0135] (Example 2)

[0136] An all-solid-state battery was manufactured in the same manner as in Example 1, except that the mixing ratio of the solid electrolyte, binder, and ethanol was changed to a weight ratio of 10:1:89 to manufacture a first solid polymer layer slurry having a viscosity of 700 cPs at room temperature (25°C).

[0137] (Example 3)

[0138] An all-solid-state battery was manufactured in the same manner as in Example 1, except that the mixing ratio of the solid electrolyte, binder, and ethanol was changed to a weight ratio of 10:3:87 to manufacture a first solid polymer layer slurry having a viscosity of 800 cPs at room temperature (25°C).

[0139] (Example 4)

[0140] An all-solid-state battery having a first solid electrolyte layer having a thickness of 30 μm was manufactured in the same manner as in Example 1, except that isopropanol was used instead of methanol to prepare a first solid polymer layer slurry having a viscosity of 500 cPs at room temperature (25°C).

[0141] (Example 5)

[0142] An all-solid-state battery having a first solid electrolyte layer with a thickness of 30 μm was manufactured in the same manner as Example 1, except that the mixing ratio of the solid electrolyte, binder, and isopropanol was changed to a weight ratio of 10:1:89 to manufacture a first solid polymer layer slurry having a viscosity of 700 cPs at room temperature (25°C).

[0143] (Comparative Example 1)

[0144] An isobutyryl isobutyrate binder solution (solid content: 50 wt%) containing butyl acrylate, an acrylate polymer, was added to the argyrodite-type solid electrolyte Li6PS5Cl and mixed. At this time, the mixing ratio of the solid electrolyte and the binder was set to 98.7:1.3 by weight.

[0145] The above mixing process was performed using a sinky mixer. 2 mm zirconia balls were added to the resulting mixture and stirred again using the sinky mixer to produce a slurry. The slurry was cast onto a polytetrafluoroethylene film and dried at room temperature to produce a solid electrolyte layer with a thickness of 100 μm.

[0146] An all-solid-state battery was manufactured using the solid electrolyte layer and the cathode and anode of Example 1 in the same manner as Example 1.

[0147] (Comparative Example 2)

[0148] (1) Manufacturing of cathode

[0149] A cathode coating layer slurry was prepared by mixing 92 wt% of carbon black having an average particle diameter (D50) of 30 nm, 3 wt% of Ag having an average particle diameter (D50) of 60 nm, 2 wt% of carboxymethylcellulose, and 3 wt% of styrene-butadiene rubber in water.

[0150] The cathode coating layer slurry was coated on a stainless steel foil current collector having a thickness of 10 μm, and then vacuum-dried at 80°C to manufacture a cathode. In the manufactured cathode, the thickness of the cathode coating layer was 2 μm.

[0151] A solid electrolyte of argyrodite type, Li6PS5Cl, butyl acrylate, and methanol were mixed. At this time, the mixing ratio of the solid electrolyte, binder, and methanol was set to 10:1:89 by weight.

[0152] The above mixing process was performed using a sinky mixer. 2 mm zirconia balls were added to the obtained mixture and stirred again using the sinky mixer to produce a solid polymer slurry having a viscosity of 500 cPs at room temperature (25°C).

[0153] The above solid polymer slurry was coated on the cathode coating layer and dried at 200°C to manufacture a cathode in which the cathode coating layer was impregnated with a solid electrolyte.

[0154] (2) Manufacturing of solid electrolyte layer

[0155] An isobutyryl isobutyrate binder solution (solid content: 50 wt%) containing butyl acrylate, an acrylate polymer, was added to the argyrodite-type solid electrolyte Li6PS5Cl and mixed. At this time, the mixing ratio of the solid electrolyte and the binder was set to 98.7:1.3 by weight.

[0156] The above mixing process was performed using a sinky mixer. 2 mm zirconia balls were added to the resulting mixture and stirred again using the sinky mixer to produce a slurry. The slurry was cast onto a polytetrafluoroethylene film and dried at room temperature to produce a solid electrolyte layer with a thickness of 100 μm.

[0157] The manufactured negative electrode, solid electrolyte layer, and positive electrode of Example 1 were sequentially laminated, and a pressure of 16 MPa was applied to manufacture an all-solid-state battery.

[0158] (Comparative Example 3)

[0159] (1) Manufacturing of cathode

[0160] A cathode coating layer slurry was prepared by mixing 92 wt% of carbon black having an average particle diameter (D50) of 30 nm, 3 wt% of Ag having an average particle diameter (D50) of 60 nm, 2 wt% of carboxymethylcellulose, and 3 wt% of styrene-butadiene rubber in water.

[0161] The cathode coating layer slurry was coated on a stainless steel foil current collector having a thickness of 10 μm, and then vacuum-dried at 80°C to manufacture a cathode. In the manufactured cathode, the thickness of the cathode coating layer was 2 μm.

[0162] (2) Manufacturing of solid electrolyte layer

[0163] A solid electrolyte of argyrodite type, Li6PS5Cl, butyl acrylate, and methanol were mixed. At this time, the mixing ratio of the solid electrolyte, binder, and methanol was set to 10:1:89 by weight.

[0164] The above mixing process was performed using a sinky mixer. 2 mm zirconia balls were added to the obtained mixture and stirred again using the sinky mixer to produce a solid polymer layer slurry having a viscosity of 500 cPs at room temperature (25°C).

[0165] The above first solid polymer layer slurry was coated on the cathode coating layer and dried at 200°C to produce a solid electrolyte layer having a thickness of 20 μm.

[0166] The manufactured negative electrode and solid electrolyte layer and the positive electrode of Example 1 were sequentially laminated, and a pressure of 16 MPa was applied to manufacture an all-solid-state battery.

[0167] (Comparative Example 4)

[0168] (1) Manufacturing of anode

[0169] Cathode active material (LiNi) 0.9 Mn 0.05 Co 0.05 A mixture was prepared by mixing O2), argyrodite-type solid electrolyte Li6PS5Cl, conductive carbon nanofibers, and binder polytetrafluoroethylene in a weight ratio of 85:15:3:1.5.

[0170] The prepared mixture was coated on an aluminum foil current collector, and then vacuum-dried at 45°C to prepare a negative electrode including a 160 μm thick positive active material layer and a 10 μm thick current collector.

[0171] (2) Manufacturing of solid electrolyte layer

[0172] A solid electrolyte of argyrodite type, Li6PS5Cl, butyl acrylate, and methanol were mixed. At this time, the mixing ratio of the solid electrolyte, binder, and methanol was set to 10:1:89 by weight.

[0173] The above mixing process was performed using a sinky mixer. 2 mm zirconia balls were added to the obtained mixture and stirred again using the sinky mixer to produce a first solid polymer layer slurry having a viscosity of 500 cPs at room temperature (25°C).

[0174] The first solid polymer layer slurry was coated on the positive electrode active material layer and dried at 200°C to produce a first solid electrolyte layer having a thickness of 20 μm.

[0175] An isobutyl isobutylate binder solution (solid content: 50 wt%) containing butyl acrylate, an acrylate polymer, was added to an argyrodite-type solid electrolyte Li6PS5Cl and mixed. At this time, the mixing ratio of the solid electrolyte and the binder was set to a weight ratio of 98.7:1.3.

[0176] The above mixing process was performed using a sinky mixer. 2 mm zirconia balls were added to the resulting mixture and stirred again using the sinky mixer to produce a slurry. The slurry was cast onto a polytetrafluoroethylene film and dried at room temperature to produce a second solid electrolyte layer with a thickness of 100 μm.

[0177] (3) Manufacturing of cathode

[0178] A cathode coating layer slurry was prepared by mixing 92 wt% of carbon black having an average particle diameter (D50) of 30 nm, 3 wt% of Ag having an average particle diameter (D50) of 60 nm, 2 wt% of carboxymethylcellulose, and 3 wt% of styrene-butadiene rubber in water.

[0179] The cathode coating layer slurry was coated on a stainless steel foil current collector having a thickness of 10 μm, and then vacuum-dried at 80°C to manufacture a cathode. In the manufactured cathode, the thickness of the cathode coating layer was 2 μm.

[0180] (4) Manufacturing of all-solid-state full cells

[0181] The manufactured positive electrode, solid electrolyte layer, and negative electrode were sequentially laminated, and a pressure of 16 MPa was applied to manufacture an all-solid-state battery. At this time, the second solid electrolyte layer was positioned so as to be in contact with the negative electrode.

[0182] (Comparative Example 5)

[0183] An all-solid-state battery having a first solid electrolyte layer having a thickness of 30 μm was manufactured in the same manner as in Example 1, except that a first solid polymer layer slurry having a viscosity of 500 cPs at room temperature (25°C) was manufactured using dimethylamine instead of methanol.

[0184] Experimental Example 1) SEM Measurement

[0185] The first solid electrolyte layers manufactured in Examples 1 to 5 were measured for planar SEM photographs as viewed from above. Among the results, the results of Example 1 are shown in Fig. 3. As shown in Fig. 3, since no consistent shape or distinct interface was observed in the cross-section of the first solid electrolyte layer, that is, no interface between particles was observed, it can be seen that the first solid electrolyte layer is an amorphous layer. In addition, since pores (black in Fig. 3) are hardly visible in Fig. 3, and the area where pores exist is less than 5% of the total area, it can be seen that the first solid electrolyte layer manufactured in Example 1 is a dense layer.

[0186] Experimental Example 2) Alcohol content measurement

[0187] In addition, the contents of ethanol, isopropanol, and methanol included in the all-solid-state batteries of Examples 1 to 5 and Comparative Examples 2 and 5 were measured by the GC (gas chromatography) / FID (flame ionization detection) method, and the results are shown in Table 1 below. In Table 1 below, the content of Comparative Example 5 is the content of dimethylamine.

[0188]

[0189] Alcohol content (weight %) Example 10.1023 Example 20.1127 Example 30.1051 Example 40.1103 Example 50.1078 Comparative Example 20.0773 Comparative Example 50.1372 (Dimethylamine content)

[0190]

[0191] As shown in Table 1 above, in the cases of Examples 1 to 5, it can be seen that the alcohol content is approximately 0.1023 wt% to 0.1127 wt%. On the other hand, in the case of Comparative Example 2, it can be seen that the alcohol content is 0.0773 wt%, which is outside the range of 0.08 wt% to 0.13 wt%.

[0192] Experimental Example 3) Evaluation of ionic conductivity

[0193] The ionic conductivity of the all-solid-state batteries manufactured according to Examples 1 to 5 and Comparative Examples 1 to 5 was measured. The results are shown in Table 2 below. The ionic conductivity was measured at room temperature (25°C) using an Electric Impedance Spectroscopy (EIR) meter of the VSP model from Bio-Logic SAS. At this time, a frequency of 10,000 MHz to 1 Hz was scanned using an amplitude of 1,000 mV at an open circuit potential.

[0194]

[0195] Ionic Conductivity (S / cm) Example 10.68 Example 20.51 Example 30.59 Example 40.45 Example 50.44 Comparative Example 10.41 Comparative Example 20.35 Comparative Example 30.38 Comparative Example 40.32 Comparative Example 50.21

[0196]

[0197] As shown in Table 2 above, the half-cells of Examples 1 to 5, in which the solid polymer layer is composed of two layers of the first and second polymer layers, and the first solid electrolyte layer containing alcohol in an amount of 0.1023 wt% to 0.1127 wt% is positioned in contact with the negative electrode, exhibit superior ionic conductivity compared to Comparative Example 1, which does not include the first solid electrolyte layer.

[0198] On the other hand, it can be seen that Comparative Example 2, which does not include the first solid electrolyte layer of the embodiment and in which the solid electrolyte is distributed throughout the cathode coating layer, exhibits ionic conductivity that is worse than that of Comparative Example 1.

[0199] In addition, it can be seen that the ionic conductivity is deteriorated compared to Comparative Example 1 even when only the first solid electrolyte layer of the embodiment is included (Comparative Example 3) or when the first solid electrolyte layer of the embodiment is in contact with the anode (Comparative Example 4).

[0200] In addition, even when the first solid electrolyte layer is formed by a wet method, it can be seen that even in Comparative Example 5, which uses an organic solvent other than alcohol, the ionic conductivity is deteriorated compared to Comparative Example 1.

[0201] Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the patent claims, the detailed description of the invention, and the attached drawings, and it is obvious that this also falls within the scope of the present invention.

Claims

1. Cathode; Bipolar; and Comprising a solid electrolyte layer positioned between the cathode and the anode, The solid electrolyte layer includes a first solid electrolyte layer in contact with the cathode and a second solid electrolyte layer in contact with the anode, An all-solid-state battery, wherein the first solid electrolyte layer is an amorphous layer and contains alcohol.

2. In paragraph 1, An all-solid-state battery wherein the first solid electrolyte layer is a dense layer.

3. In paragraph 1, An all-solid-state battery wherein the content of the alcohol is 0.08 wt% to 0.13 wt% with respect to 100 wt% of the first solid electrolyte layer.

4. In paragraph 1, An all-solid-state battery, wherein the first solid electrolyte layer includes a first solid electrolyte, and the first solid electrolyte is a sulfide-based solid electrolyte.

5. In paragraph 1, An all-solid-state battery, wherein the second solid electrolyte layer comprises a second solid electrolyte, and the second solid electrolyte is a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a halide-based solid electrolyte, or a solid polymer electrolyte.

6. In paragraph 1, The above cathode comprises a cathode current collector and a cathode coating layer positioned on the cathode current collector, An all-solid-state battery, wherein the cathode coating layer comprises a metal, a carbon-based material, and a binder.

7. In paragraph 6, An all-solid-state battery wherein the carbon-based material is amorphous carbon, crystalline carbon or a mixture thereof.

8. In paragraph 6, An all-solid-state battery wherein the metal is Ag, Au, Sn, Zn, Al, Mg, Ge, Cu, In, Ni, Bi, Pt, Pd or a combination thereof.

9. In paragraph 1, An all-solid-state battery wherein the alcohol is ethanol, propanol, isopropanol, butanol, t-butyl alcohol, or a combination thereof.

10. In paragraph 1, An all-solid-state battery wherein the thickness of the first solid electrolyte layer is 10 ㎛ to 200 ㎛.

11. In paragraph 1, An all-solid-state battery wherein the thickness of the second solid electrolyte layer is 10 ㎛ to 200 ㎛.

12. In paragraph 1, An all-solid-state battery, wherein the second solid electrolyte layer includes a solid electrolyte having a particle size exceeding 0.1 ㎛.

13. In paragraph 12, An all-solid-state battery, wherein the particle size of the above-mentioned solid electrolyte is 0.5 ㎛ to 20 ㎛.

14. Coating and drying a first solid electrolyte layer composition having a viscosity of 5 cPs to 1000 cPs on the cathode to form a first solid electrolyte layer; A laminate is manufactured by positioning a second solid electrolyte layer and an anode on the first solid electrolyte layer; Pressurizing the above laminate A method for manufacturing an all-solid-state battery including a process.

15. In paragraph 14, A method for manufacturing an all-solid-state battery, wherein the first solid electrolyte layer composition comprises a first solid electrolyte and alcohol.

16. In paragraph 14, A method for manufacturing an all-solid-state battery wherein the alcohol is ethanol, propanol, isopropanol, butanol, t-butyl alcohol, or a combination thereof.

17. In paragraph 14, A method for manufacturing an all-solid-state battery, wherein the content of the first solid electrolyte is 1 wt% to 20 wt% with respect to 100 wt% of the total first solid electrolyte layer composition.

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