Negative electrode for all solid-state battery and all solid-state battery including same

Abstract

The present invention relates to a negative electrode for an all solid-state battery and an all solid-state battery including same. The negative electrode comprises: a current collector; a first layer positioned on the current collector and including a Si-C composite; and a second layer positioned on the first layer and including a carbon-based material and a metal, wherein the all solid-state battery has a ratio (N / P ratio) of negative electrode capacity / positive electrode capacity of 0.5 to 2.

Description

Anode for an all-solid-state battery and an all-solid-state battery comprising the same

[0001] The present invention relates to a cathode for an all-solid-state battery and an all-solid-state battery including 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] Development of all-solid-state batteries using lithium metal as the cathode is underway. All-solid-state batteries are composed entirely of solid materials, specifically those using 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 a cathode for an all-solid-state battery exhibiting excellent safety and high energy density.

[0005] Another embodiment provides an all-solid-state battery comprising the above negative electrode.

[0006] One embodiment provides an all-solid-state battery negative electrode comprising: a current collector; a first layer positioned on the current collector and comprising a Si-carbon composite; and a second layer positioned on the first layer and comprising a carbon-based material and a metal, wherein the all-solid-state battery has an anode capacity / positive electrode capacity ratio (N / P ratio) of 0.5 to 2.

[0007] Another embodiment provides an all-solid-state battery comprising the cathode, the anode, and a solid electrolyte positioned between the cathode and the anode.

[0008] An all-solid-state battery cathode according to one embodiment includes a Si-carbon composite, and thus can exhibit excellent safety and high energy density.

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

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

[0011] 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.

[0012] 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.

[0013] “Combination of these” means a mixture, laminate, composite, copolymer, alloy, blend, reaction product, etc. of the components.

[0014] It should be understood that terms such as "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.

[0015] 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.

[0016] 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.

[0017] Throughout this specification, the description of “A and / or B” means “A or B or both.”

[0018] Unless otherwise specified herein, when a part such as a layer, film, region, plate, etc. is said to be “on” another part, this includes not only cases where it is “directly on” the other part, but also cases where there is another part in between.

[0019] 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 approximately 28 kHz at an output of 60 W, and the average particle diameter (D50) based on 50% of the particle diameter distribution in the measuring device can be calculated.

[0020] "Thickness" may be measured, for example, from photographs taken with an optical microscope such as a scanning electron microscope.

[0021] An anode for an all-solid-state battery according to one embodiment includes a current collector, a first layer positioned on the current collector and comprising a Si-carbon composite, and a second layer positioned on the first layer and comprising a carbon-based material and a metal.

[0022] According to one embodiment, the negative electrode may be an all-solid-state battery negative electrode having an N / P ratio, which is a ratio of negative electrode capacity to positive electrode capacity, of 0.5 to 2. In one embodiment, the N / P ratio may be 0.5 to 1.5, 0.5 to 1.2, or 0.5 to 1. When the N / P ratio of an all-solid-state battery including the negative electrode according to one embodiment satisfies the above range, it may exhibit improved capacity retention.

[0023] In one embodiment, the capacity of the N / P ratio may be the theoretical capacity of the Si-carbon composite. For example, the N / P ratio may be a value obtained from the theoretical capacity of the first layer comprising the Si-carbon composite. Since the theoretical capacity of the second layer comprising a carbon-based material and a metal is close to infinity, the N / P ratio cannot be defined. Therefore, when the negative electrode comprises only the second layer, it cannot be defined by the N / P ratio.

[0024] FIG. 1 schematically illustrates the structure of a cathode (400) according to one embodiment, wherein the cathode (400) includes a current collector (401), a first layer (403), and a second layer (405).

[0025] In an all-solid-state battery, lithium ions released from the positive active material during charge / discharge move toward the negative electrode, causing precipitation on the surface of the current collector to form a lithium-containing layer, for example, a lithium precipitation layer. The second layer may play a role in assisting this lithium precipitation, and the metal and carbon-based materials included in the second layer do not function as negative electrode active materials that directly participate in the charge / discharge reaction. For example, a lithium-containing layer, for example, a lithium precipitation layer, may be formed on the current collector due to the precipitation of lithium ions, and the lithium precipitation layer may function as a negative electrode active material. Such a negative electrode is called a precipitation-type negative electrode.

[0026] Such precipitation-type negative electrodes may exhibit low safety due to lithium precipitation. According to one embodiment, the negative electrode includes a first layer comprising a Si-carbon composite between the current collector and the second layer, such that the Si-carbon composite can react with lithium ions to precipitate on the current collector in the form of a lithium alloy, thereby improving safety.

[0027] The first layer comprises a Si-carbon composite, and since this Si-C composite can act as an active material participating in charge-discharge reactions, it can exhibit high capacity and high energy density. If the first layer comprises only silicon, safety may be deteriorated compared to if it comprises a Si-carbon composite, and if it comprises only a carbon-based material, the capacity is low and thus unsuitable.

[0028] In one embodiment, the ratio of the thickness of the first layer to the thickness of the second layer may be 1.5:1 to 6:1, 1.5:1 to 4.5:1, or 1.5:1 to 3:1. When the ratio of the thickness of the first layer to the thickness of the second layer satisfies the above range, safety can be further improved, and high capacity and high energy density can be further improved.

[0029] In one embodiment, the thickness of the first layer may be 5 μm to 100 μm, 10 μm to 60 μm, or 30 μm to 40 μm. When the thickness of the first layer is within the above range, it may exhibit higher capacity and higher energy density.

[0030] In one embodiment, the thickness of the second layer may be 1 μm to 50 μm, 5 μm to 30 μm, or 10 μm to 15 μm. When the thickness of the second layer is within the above range, better safety may be exhibited.

[0031] [1st floor]

[0032] The Si-carbon composite included in the first layer may include silicon particles and a carbon-based material. The silicon particles may be silicon nanoparticles. The carbon-based material may be amorphous carbon, or may be amorphous carbon and crystalline carbon.

[0033] In another embodiment, the silicon-carbon composite may include silicon nanoparticles and an amorphous carbon coating layer positioned on the surface of the silicon nanoparticles.

[0034] The above silicon-carbon composite may include an assembly in which at least one silicon nanoparticle is assembled and an amorphous carbon coating layer positioned on the surface of the assembly.

[0035] The particle size of the above silicon nanoparticles may be 10 nm to 1,000 nm, and according to another embodiment, 10 nm to 200 nm, or 20 nm to 150 nm. When the particle size of the silicon nanoparticles is within the above range, excessive volume expansion occurring during charge and discharge can be suppressed, and disconnection of the conductive path due to particle fragmentation during charge and discharge can be prevented.

[0036] In the amorphous carbon coating layer, the amorphous carbon may be soft carbon, hard carbon, mesophase pitch carbide, calcined coke, or a combination thereof. The thickness of the amorphous carbon coating layer may be 1 nm to 2 μm, 1 nm to 500 nm, 10 nm to 300 nm, or 20 nm to 200 nm. In one embodiment, the thickness of the amorphous carbon coating layer may be measured by a SEM image or a TEM image of a cross-section of a silicon-carbon composite, but is not limited thereto, and may be measured by any method that can measure the amorphous carbon coating layer. When the thickness of the amorphous carbon coating layer is within the above range, silicon volume expansion during charge and discharge can be well suppressed.

[0037] The above silicon-carbon composite may further comprise crystalline carbon. When the silicon-carbon composite further comprises crystalline carbon, it may comprise an assembly in which silicon nanoparticles and crystalline carbon are assembled, and an amorphous carbon coating layer positioned on the surface of the assembly.

[0038] The above crystalline carbon may include natural graphite, artificial graphite, or a combination thereof in the form of amorphous, plate-like, flake-like, spherical, or fiber-like materials.

[0039] When the silicon-carbon composite includes silicon nanoparticles and an amorphous carbon coating layer, the content of the silicon nanoparticles may be 30 wt% to 70 wt%, or may be 40 wt% to 65 wt%, based on 100 wt% of the total silicon-carbon composite. In addition, the content of the amorphous carbon coating layer may be 30 wt% to 70 wt%, or may be 35 wt% to 60 wt%, based on 100 wt% of the total silicon-carbon composite.

[0040] When the silicon-carbon composite further includes crystalline carbon, the content of the silicon nanoparticles may be 20 wt% to 70 wt%, or 25 wt% to 65 wt%, based on 100 wt% of the total silicon-carbon composite. The content of amorphous carbon may be 25 wt% to 70 wt%, or 25 wt% to 60 wt%, based on 100 wt% of the total silicon-carbon composite, and the content of crystalline carbon may be 1 wt% to 20 wt%, or 5 wt% to 15 wt%.

[0041] The amorphous carbon may be soft carbon, hard carbon, mesophase, pitch carbide, calcined coke, or a combination thereof.

[0042] In one embodiment, the first layer may further comprise a first binder. The first binder may be a non-aqueous binder, an aqueous binder, or a combination thereof.

[0043] Examples of the non-aqueous binder include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or combinations thereof.

[0044] The above-mentioned aqueous binder may be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluoroelastomer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0045] The first binder may be a cellulose-based compound, and the cellulose-based compound may be used together with the aqueous binder. The cellulose-based compound may be a mixture of one or more of carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or an alkali metal salt thereof. The alkali metal may be Na, K, or Li. The cellulose-based compound may function as a binder or as a thickener capable of providing viscosity. Accordingly, the cellulose-based compound may be used in an appropriate amount within the binder amount, but may be, for example, 0.1 to 3 parts by weight based on 100 parts by weight of the Si-carbon composite.

[0046] In the first layer, the content of the Si-carbon composite may be 90 wt% to 99 wt%, 95 wt% to 99 wt%, or 97 wt% to 99 wt% based on the total weight of the first layer.

[0047] In the first layer, the content of the first binder may be 1 wt% to 10 wt%, 1 wt% to 5 wt%, or 1 wt% to 3 wt% based on the total weight of the first layer.

[0048] The first layer may further include a conductive material. The conductive material is used to impart conductivity to the electrode, and any material that does not cause chemical changes and is electronically conductive can be used in the battery. Specific examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metal-based materials in the form of metal powder or metal fibers, including copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0049] When the first layer further includes a conductive material, the content of the conductive material may be 0.5 wt% to 5 wt%, 0.5 wt% to 4 wt%, or 0.5 wt% to 3 wt%, based on the total weight of the first layer. When the conductive material is further included, the content of the first binder in the first layer may be appropriately adjusted depending on the content of the conductive material.

[0050] The first layer may further include an organic filler. The organic filler may be polyethylene glycol diacrylate (PEGDA), polyethylene glycol diglycidyl ether (PEGDE), polydimethylsiloxane (PDMS), or a combination thereof. When the first layer further includes an organic filler, the content of the organic filler may be appropriately adjusted, and may be, for example, 0.1 wt% to 20 wt%, or 0.5 wt% to 10 wt%, based on the total weight of the first layer.

[0051] [2nd floor]

[0052] In the second layer, the carbon-based material and the metal may be mixed and present, or the metal may be present supported on the carbon-based material.

[0053] The carbonaceous material may be, for example, crystalline carbon, amorphous carbon, or a combination thereof, or 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 amorphous, plate-shaped, flake-shaped, spherical, or fibrous. 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.

[0054] 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.

[0055] 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.

[0056] In one embodiment, the particle size of the primary particles may be 20 nm to 100 nm, 20 nm to 90 nm, 20 nm to 80 nm, or 30 nm to 70 nm.

[0057] In one embodiment, the particle size of the secondary particles may be 1 μm to 20 μm, 2 μm to 15 μm, or 3 μm to 10 μm.

[0058] 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.

[0059] The above metal may be Ag, Au, Sn, Zn, Al, Mg, Ge, Cu, In, Ni, Bi, Pt, Pd or a combination thereof, and may be Ag. The second layer may exhibit improved electrical conductivity because it includes such a metal.

[0060] The metal may be a nanoparticle, and the size of the metal nanoparticle may be, for example, an average size of 5 nm to 800 nm, 5 nm to 700 nm, 5 nm to 500 nm, or 5 nm to 300 nm, but is not limited thereto, and any nanometer-sized particle may be appropriately used. When the metal nanoparticle having such a nanosize is used, the battery characteristics (e.g., life characteristics) of the all-solid-state battery can be improved. When the metal particle size increases to the micrometer level, the uniformity of the metal particles in the second 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 appropriate.

[0061] In one embodiment, the content of the metal may be 14 wt% to 35 wt%, 18 wt% to 25 wt%, or 20 wt% to 24 wt%, based on 100 wt% of the total weight of the second layer.

[0062] Additionally, the carbon-based material may be 55 wt% to 80 wt%, 60 wt% to 75 wt%, or 65 wt% to 70 wt% with respect to 100 wt% of the entire second layer.

[0063] The second layer may include a second binder. The second binder may be a non-aqueous binder.

[0064] 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.

[0065] The second binder may be present in an amount of 1 wt% to 15 wt% relative to 100 wt% of the entire second layer. For example, the second binder may be present in an amount of 1 wt% to 14 wt%, 1 wt% to 12 wt%, 1 wt% to 10 wt%, 2 wt% to 8 wt%, or 2 wt% to 7 wt% relative to 100 wt% of the entire second layer.

[0066] When the second binder is included in the second layer in the above content range, electrical resistance and adhesive strength can be improved, thereby improving the characteristics (battery capacity and output characteristics) of the all-solid-state battery.

[0067] In one embodiment, the second layer may further include a solid electrolyte. As the second layer further includes a solid electrolyte, interfacial adhesion with the solid electrolyte membrane can be improved and volume expansion issues can be alleviated.

[0068] The above 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.

[0069] In one embodiment, the 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 d A 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.

[0070] 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).

[0071] As specific examples, Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 , 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.

[0072] The above-mentioned sulfide-based solid electrolyte may be amorphous, crystalline, or a mixture thereof. For example, the above-mentioned sulfide-based solid electrolyte may be obtained by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10, or a molar ratio of 50:50 to 80:20. Within the above-mentioned 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.

[0073] 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.

[0074] Of course, a commercially available solid electrolyte can be used as the sulfide-based solid electrolyte.

[0075] 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-x Si 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.

[0076] The above solid polymer electrolytes include, for example, polyethylene oxide, poly(diallyldimethylammonium)trifluoromethanesulfonyl imide (poly(diallyldimethylammonium)TFSI), Cu3N, Li3N, LiPON, Li3PO4·Li2S·SiS2, Li2S·GeS2·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.

[0077] 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.

[0078] 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.

[0079] The second layer may further include additives such as fillers, dispersants, and ionic conductive agents, for example. Furthermore, known materials commonly used in all-solid-state batteries may be used as fillers, dispersants, and ionic conductive agents that can be included in the second cathode coating layer.

[0080] [Current collector]

[0081] 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 current collector may be 1 μm to 20 μm, 5 μm to 15 μm, or 7 μm to 10 μm.

[0082] 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.

[0083] 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.

[0084] 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 first layer. The lithium-containing layer may include a lithium alloy, for example, a Li-Si alloy.

[0085] 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, it may have the advantage of being able to appropriately perform the role of a lithium storage tank and further improving the lifespan.

[0086] The lithium-containing layer may further include lithium metal. The lithium-containing layer may include lithium metal because, after manufacturing the battery, when charging, lithium ions released from the positive electrode active material pass through the solid electrolyte and move toward the negative electrode, and these lithium ions are not completely absorbed into the first layer, but remain, resulting in lithium being precipitated and deposited on the negative electrode current collector, and thus being included.

[0087] The above charging process may be a chemical reaction process performed once to three times at a rate of 0.05C to 1C at a temperature of about 25°C to 50°C. When a lithium-containing layer is formed, lithium contained in the lithium-containing layer can be ionized and move toward the positive electrode during discharge, and this lithium can be used as an anode active material.

[0088] In one embodiment, since the lithium-containing layer is positioned between the current collector and the first layer, the first 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.

[0089] [Method for manufacturing cathode]

[0090] A first layer composition is prepared by adding a Si-carbon complex to a first solvent, and a second layer composition is prepared by adding a carbon-based material and a metal to a second solvent.

[0091] A first binder may be further added to the first layer composition, and a conductive material, an organic filler, or a combination thereof may also be further added. The first solvent may be, but is not limited to, N-methyl pyrrolidone, water, or the like.

[0092] A second binder may be further added to the second layer composition, and a solid electrolyte may also be further added. In addition, additives such as fillers, dispersants, and ionic conductive agents may be further added to the second layer composition. The second solvent may be isobutyryl isobutyrate, xylene, toluene, benzene, hexane, or a combination thereof.

[0093] The Si-carbon composite, the carbon-based material, the metal, the first binder, the second binder, the solid electrolyte, and the additive are as described above. In addition, the content of each composition can be used so that the content of each component included in the manufactured negative electrode is obtained.

[0094] The first layer composition is applied to a current collector, dried to form a first layer, and then the second layer composition is applied to the first layer, dried to form a second layer, thereby manufacturing a negative electrode. The drying process may be vacuum drying.

[0095] All-solid-state battery

[0096] An all-solid-state battery according to one embodiment includes the cathode, the anode, and a solid electrolyte layer positioned between the cathode and the anode.

[0097] Solid electrolyte layer

[0098] In one embodiment, the solid electrolyte layer may include a solid electrolyte. It 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.

[0099] In one embodiment, the solid electrolyte may be a sulfide-based solid electrolyte. Such sulfide-based solid electrolytes are suitable because they have superior ionic conductivity compared to other solid electrolytes, such as oxide-based solid electrolytes, and can exhibit superior life characteristics over a wider operating range.

[0100] The above sulfide-based solid electrolyte, oxide-based solid electrolyte, halide-based solid electrolyte, and solid polymer electrolyte are as described above. In addition, the solid electrolyte included in the solid electrolyte layer may be the same as or different from the solid electrolyte included in the second cathode coating layer.

[0101] The above solid electrolyte may be in the form of particles. At this time, the average particle diameter (D50) of the solid electrolyte may be 5.0 ㎛ or less, for example, 0.1 ㎛ to 5.0 ㎛, 0.5 ㎛ to 5.0 ㎛, 0.5 ㎛ to 4.0 ㎛, 0.5 ㎛ to 3.0 ㎛, 0.5 ㎛ to 2.0 ㎛, or 0.5 ㎛ to 1.0 ㎛.

[0102] The above solid electrolyte layer may further include a binder. At this time, the binder may be styrene butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, an acrylate polymer, or a combination thereof, but is not limited thereto, 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.

[0103] The binder content in the solid electrolyte layer can be appropriately controlled and does not need to be limited.

[0104] The above solid electrolyte layer can be formed by adding a solid electrolyte to a binder solution, coating the same on a base film, and drying the same. The solvent for the binder solution may be isobutyryl isobutyrate, xylene, toluene, benzene, hexane, or a combination thereof. Since the solid electrolyte layer formation process is widely known in the art, a detailed description thereof will be omitted herein.

[0105] The thickness of the solid electrolyte layer may be, for example, 10 μm to 150 μm.

[0106] The solid electrolyte layer may further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0107] The above 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 solid electrolyte layer.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] In the above solid electrolyte layer, the weight ratio of the solid electrolyte and the ionic liquid 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.

[0114] Bipolar

[0115] 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.

[0116] 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. The composite oxide may be a lithium transition metal composite oxide, and specific examples thereof include a lithium nickel-based oxide, a lithium cobalt-based oxide, a lithium manganese-based oxide, a lithium iron phosphate-based compound, a cobalt-free nickel-manganese-based oxide, or a combination thereof.

[0117] As an example, a compound represented by any one of the following chemical formulas may be used: Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Lia Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 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); Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3(0≤f≤2); Li a FePO4(0.90≤a≤1.8).

[0118] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; L 1is Mn, Al or a combination thereof.

[0119] For example, the cathode active material may be a high-nickel cathode active material in which the nickel content is 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more and 99 mol% or less, based on 100 mol% of metals excluding lithium in a lithium transition metal composite oxide. The high-nickel cathode active material can realize high capacity and thus can be applied to high-capacity, high-density lithium secondary batteries.

[0120] 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.

[0121] 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.

[0122] In addition, as the above coating layer, any known coating layer for the positive electrode active material of an all-solid-state battery can be applied. For example, it can be a buffer layer that plays a role in lowering the interfacial resistance between the positive electrode active material and the solid electrolyte. For example, the buffer layer can include a lithium-metal-oxide, wherein the metal can be one or more elements selected from the group consisting of Al, B, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ta, V, W, and Zr. Specific examples of the buffer layer include Li2O-ZrO2 (LZO), LiNbO2, etc.

[0123] 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.

[0124] The average particle size of the positive electrode active material may be 1 μm to 25 μm, for example, 3 μm to 25 μm, 1 μm to 20 μm, 1 μm to 18 μm, 3 μm to 15 μm, or 5 μm to 15 μm. For example, the positive electrode active material may include small particles having an average particle size (D50) of 1 μm to 9 μm and large particles having an average particle size (D50) of 10 μm to 25 μm. A positive electrode active material having such a particle size range can be harmoniously mixed with other components within a positive electrode active material layer and can realize high capacity and high energy density.

[0125] The above-mentioned positive electrode active material may be in the form of a secondary particle formed by agglomeration of a plurality of primary particles, or may be in the form of a single crystal. In addition, the above-mentioned positive electrode active material may be in the form of a spherical or nearly spherical shape, or may be polyhedral or irregular.

[0126] In addition, the content of the positive electrode active material in the positive electrode active material layer is not particularly limited, and may be within a range applicable to the positive electrode active material layer of a conventional all-solid-state secondary battery. For example, with respect to the total 100 wt% of the positive electrode active material layer, the positive electrode active material may be included in an amount of 55 wt% to 99.5 wt%, for example, 65 wt% to 95 wt%, or 75 wt% to 91 wt%.

[0127] The above positive electrode active material layer may further include a binder and / or a conductive material.

[0128] 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.

[0129] 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 positive electrode active material layer. Within the above content range, the binder can sufficiently exhibit adhesive ability without deteriorating battery performance.

[0130] 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.

[0131] 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. Within the above content range, the conductive material can improve electrical conductivity without degrading battery performance.

[0132] The above-described positive electrode active material layer may additionally include a solid electrolyte. The solid electrolyte included in the positive electrode active material layer 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. The solid electrolyte is as described in the above-described solid electrolyte, and may be the same as or different from the solid electrolyte included in the solid electrolyte.

[0133] With respect to the total weight of the positive electrode active material layer, the solid electrolyte may be included in an amount of 0.1 wt% to 35 wt%, for example, 1 wt% to 35 wt%, 5 wt% to 30 wt%, 8 wt% to 25 wt%, or 10 wt% to 20 wt%. In addition, with respect to the total weight of the positive electrode active material and the solid electrolyte in the positive electrode active material layer, 65 wt% to 99 wt% of the positive electrode active material and 1 wt% to 35 wt% of the solid electrolyte may be included, for example, 80 wt% to 90 wt% of the positive electrode active material and 10 wt% to 20 wt% of the solid electrolyte may be included. When the solid electrolyte is included in the positive electrode in such an amount, the efficiency and life characteristics of the all-solid-state battery can be improved without reducing the capacity.

[0134] The above anode current collector may be made of, 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.

[0135] [Method of manufacturing anode]

[0136] A positive electrode composition is prepared by adding a positive electrode active material, a binder, and / or a conductive agent to a solvent. A solid electrolyte may also be further added to the positive electrode composition.

[0137] The solvent may be isobutyryl isobutyrate, xylene, toluene, benzene, hexane or a combination thereof.

[0138] The above positive electrode composition is applied to a current collector, dried, and rolled to manufacture a positive electrode.

[0139] The positive electrode active material, the binder, the conductive material, and the solid electrolyte are as described above. In addition, the content of each composition may be used so as to be the content included in the positive electrode described above.

[0140] Elastic layer

[0141] An all-solid-state battery according to one embodiment may further include an elastic layer for buffering thickness changes that occur during charging and discharging. The elastic layer may be positioned between the negative electrode and the case.

[0142] The elastic layer 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 elastic layer may be a cushioning material in the form of a polymer sheet.

[0143] <Method for manufacturing an all-solid-state battery>

[0144] An all-solid-state battery according to one embodiment can be manufactured by a step of preparing a laminate by positioning a cathode, an anode, and a solid electrolyte layer between the cathode and the anode, and pressing the laminate.

[0145] The pressurizing process can be performed at a temperature ranging from 25°C to 90°C. In addition, the pressurizing process can be performed by pressurizing at a pressure of 550 MPa or less, for example, 500 MPa or less, for example, 1 MPa to 500 MPa. The pressurizing time can vary depending on the temperature and pressure, and can be, for example, less than 30 minutes. The pressurizing process can be, for example, isostatic pressing, roll pressing, plate pressing, or warm isostatic pressing.

[0146] 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 bicell 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.

[0147] 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.

[0148] Fig. 2 is a cross-sectional view of an all-solid-state battery according to an embodiment. Referring to Fig. 2, the all-solid-state battery (100) may have a structure in which an electrode assembly in which a negative electrode (400) including a negative current collector (401), a first layer (403) and a second layer (405), a solid electrolyte layer (300), and a positive electrode (200) including a positive active material layer (203) and a positive current 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).

[0149] Additionally, when the all-solid-state battery is charged, lithium ions may be released from the positive electrode active material and deposited on the negative electrode current collector (401), thereby forming a lithium-containing layer (lithium deposition layer).

[0150] Although FIG. 2 illustrates one electrode assembly including a cathode (400), a solid electrolyte layer (300), and a cathode (200), an all-solid-state battery may be manufactured by stacking two or more electrode assemblies. For example, 2 to 100, 3 to 50, 4 to 20, etc. may be stacked.

[0151] Hereinafter, examples and comparative examples of the present invention will be described. However, the following examples are merely examples of the present invention, and the present invention is not limited to the following examples.

[0152] (Example 1)

[0153] (1) Cathode manufacturing

[0154] A first layer composition was prepared by mixing 93 wt% of Si-carbon composite and 7 wt% of polyvinylidene fluoride binder in an N-methyl pyrrolidone solvent.

[0155] The above Si-carbon composite was used as an assembly in which silicon nanoparticles having an average particle diameter (D50) of 100 nm and soft carbon were assembled and had a soft carbon coating layer. At this time, the content of silicon nanoparticles was 40 wt% with respect to the total weight of the silicon-carbon composite, the content of the soft carbon was 60 wt%, and the thickness of the soft carbon coating layer was 100 nm.

[0156] Carbon black having a primary particle size (D50) of about 30 nm and silver (Ag) having an average particle size (D50) of about 60 nm were mixed in a weight ratio of 3:1, and 0.25 g of this mixture was added to 2 g of an N-methyl pyrrolidone binder solution containing a polyvinylidene fluoride binder (polyvinylidene fluoride binder content: 7 wt% with respect to 100 wt% of the total binder solution), and mixed to prepare a second layer composition.

[0157] The first layer composition was applied to a nickel foil current collector using a bar coater and vacuum-dried to form a first layer, and then the second layer composition was applied to the first layer using a bar coater and vacuum-dried to form a second layer, thereby manufacturing a negative electrode. The thickness of the first layer was 15 μm, and the thickness of the second layer was 10 μm.

[0158] (2) Anode manufacturing

[0159] LiNi 0.8 Co 0.15 Mn 0.05 A cathode composition was prepared by mixing 85 wt% of O2 cathode active material, 13.5 wt% of lithium argyrodite-type solid electrolyte Li6PS5Cl, 1.0 wt% of polyvinylidene fluoride binder, and 0.5 wt% of carbon nanotube conductive material in a xylene solvent.

[0160] The manufactured positive electrode composition was coated on an aluminum foil current collector using a bar coater, dried, and rolled to manufacture a positive electrode.

[0161] (3) Manufacturing of solid electrolyte layer

[0162] 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.

[0163] 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.

[0164] (4) All-solid-state battery manufacturing

[0165] The above-mentioned negative electrode, the above-mentioned solid electrolyte layer, and the above-mentioned positive electrode were sequentially laminated, and then hydrostatically pressed at 380 MPa to manufacture an all-solid-state battery. The N / P ratio of the manufactured battery was 0.5.

[0166] (Example 2)

[0167] An all-solid-state battery having an N / P ratio of 1 was manufactured in the same manner as Example 1, except that the thickness of the first layer was changed to 30 μm and the thickness of the second layer was changed to 10 μm.

[0168] (Comparative Example 1)

[0169] An all-solid-state battery was manufactured in the same manner as Example 1, except that the thickness of the first layer was changed to 0 μm and the thickness of the second layer to 10 μm. The manufactured battery cannot define N / P.

[0170] (Comparative Example 2)

[0171] An all-solid-state battery having an N / P ratio of 1 was manufactured in the same manner as Example 1, except that the thickness of the first layer was changed to 30 μm and the thickness of the 21st layer was changed to 0 μm.

[0172] (Comparative Example 3)

[0173] An all-solid-state battery having an N / P ratio of 1.5 was manufactured in the same manner as Example 1, except that the thickness of the first layer was changed to 45 μm and the thickness of the second layer was changed to 0 μm.

[0174] (Comparative Example 4)

[0175] An all-solid-state battery having an N / P ratio of 2.5 was manufactured in the same manner as Example 1, except that the thickness of the first layer was changed to 75 μm and the thickness of the second layer was changed to 10 μm.

[0176] The N / P ratios of the all-solid-state batteries according to Examples 1 to 2 and Comparative Examples 1 to 4 are summarized in Table 1 below. Since the all-solid-state battery of Comparative Example 1 is a battery for which N / P cannot be defined, the N / P ratio is indicated as “-“.

[0177] Experimental Example 1) Capacity retention rate evaluation

[0178] The all-solid-state batteries of Examples 1 and 2 and Comparative Examples 1 to 3 were charged and discharged 160 times at 0.1 C at 45°C. The ratio of the 160-cycle discharge capacity to the 1-cycle discharge capacity was obtained. The all-solid-state battery of Comparative Example 3 showed a rapid decrease in lifespan when charged and discharged 70 times at 0.1 C at 45°C, and charging and discharging were stopped at 70 times. Therefore, the ratio of the 70-cycle discharge capacity to the 1-cycle discharge capacity was obtained for Comparative Example 3.

[0179] The all-solid-state battery of Comparative Example 4 was charged and discharged at 0.1 C at 45°C, but after two charge and discharge cycles, the discharge capacity decreased to almost 0, and therefore no further experiments were conducted.

[0180] The results are shown in Table 1 as capacity retention rate.

[0181]

[0182] 1st layer thickness: 2nd layer thickness N / P specific capacity retention rate (%) Example 115:100.575.62 Example 230:10163.12 Comparative example 10:10-57.96 Comparative example 230:0153.90 Comparative example 345:01.536.5

[0183]

[0184] As shown in Table 1 above, the capacity retention rates of Examples 1 and 2 were found to be significantly superior to those of Comparative Examples 1 and 2. In addition, in the case of Comparative Example 3, it can be seen that the capacity retention rate at 70 cycles sharply decreased to 36.5%.

[0185] 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. Current collector; A first layer positioned on the current collector and comprising a Si-carbon composite; and A second layer located on the first layer and containing a carbon-based material and a metal As a cathode for an all-solid-state battery, The above all-solid-state battery is an all-solid-state battery negative electrode having a negative electrode capacity / positive electrode capacity ratio (N / P ratio) of 0.5 to 2.

2. In paragraph 1, An all-solid-state battery negative electrode, wherein the ratio of the thickness of the first layer to the thickness of the second layer is 1.5:1 to 6:

1.

3. In paragraph 1, An all-solid-state battery negative electrode, wherein the ratio of the thickness of the first layer to the thickness of the second layer is 1.5:1 to 4.5:

1.

4. In paragraph 1, An all-solid-state battery negative electrode having a thickness of the first layer of 5 μm to 100 μm.

5. In paragraph 1, An all-solid-state battery negative electrode having a thickness of the second layer of 1 μm to 50 μm.

6. In paragraph 1, The above Si-carbon composite is an anode for an all-solid-state battery comprising silicon nanoparticles and amorphous carbon.

7. In paragraph 1, The above Si-carbon composite is an all-solid-state battery negative electrode comprising secondary particles assembled with silicon primary particles and amorphous carbon located on the surfaces of the primary particles and the secondary particles.

8. In paragraph 6, An all-solid-state battery negative electrode wherein the Si-carbon composite further comprises crystalline carbon.

9. In paragraph 1, The above carbon-based material is a cathode for an all-solid-state battery, which is crystalline carbon, amorphous carbon or a combination thereof.

10. In paragraph 1, The above carbon-based material is an amorphous carbon-based negative electrode for an all-solid-state battery.

11. In paragraph 10, The above amorphous carbon is a cathode for an all-solid-state battery, which is carbon black, acetylene black, Denka black, Ketjen black, furnace black, activated carbon, graphene or a combination thereof.

12. In paragraph 1, The above metal is an anode for an all-solid-state battery, which is Ag, Au, Sn, Zn, Al, Mg, Ge, Cu, In, Ni, Bi, Pt, Pd or a combination thereof.

13. In paragraph 1, The above metal is an all-solid-state battery negative electrode of Ag.

14. The cathode of any one of paragraphs 1 to 13; Bipolar; and A solid electrolyte layer positioned between the cathode and the anode An all-solid-state battery comprising:

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