Negative electrode for all-solid-state battery, all-solid-state battery comprising same, and method for manufacturing negative electrode for all-solid-state battery

Abstract

The present invention relates to a negative electrode for an all-solid-state battery, an all-solid-state battery including same, and a method for manufacturing an all-solid-state battery. More specifically, the negative electrode for an all-solid-state battery includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein the negative electrode layer includes a negative electrode current collector, a first coating layer on the negative electrode current collector, and a second coating layer on the first coating layer. The first coating layer includes a first carbon-based material, a first metal, and a first binder, and the second coating layer includes a second carbon-based material, a second metal, and a second binder. The first binder includes a rubber-based binder, while the second binder includes a non-rubber-based binder.

Description

Anode for an all-solid-state battery, an all-solid-state battery including the same, and a method for manufacturing the anode for an all-solid-state battery

[0001] The present invention relates to a negative electrode for an all-solid-state battery, an all-solid-state battery including the same, and a method for manufacturing the negative electrode for an all-solid-state battery.

[0002]

[0003] Recent industrial demands have led to the active development of batteries with high energy density and safety. For example, lithium-ion batteries are being used not only in information and communication devices, but also in the automotive sector. Safety is particularly important in the automotive sector, as it is directly related to life.

[0004] Recently, all-solid-state batteries, which replace the electrolyte with a solid electrolyte, have been proposed. By eliminating the use of flammable organic dispersion media, all-solid-state batteries significantly reduce the risk of fire or explosion in the event of a short circuit. Therefore, these all-solid-state batteries can significantly improve safety compared to lithium-ion batteries that use electrolytes.

[0005]

[0006] The problem to be solved by the present invention is to provide an anode for an all-solid-state battery that suppresses side reactions at the interface between a solid electrolyte layer and a cathode and reduces the interfacial resistance between the solid electrolyte layer and the cathode.

[0007] Another problem to be solved by the present invention is to provide an all-solid-state battery with improved high-rate characteristics and lifespan characteristics.

[0008]

[0009] According to the concept of the present invention, an all-solid-state battery comprises a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein the negative electrode layer may include a negative electrode current collector, a first coating layer on the negative electrode current collector, and a second coating layer on the first coating layer. The first coating layer may include a first carbon-based material, a first metal, and a first binder, and the second coating layer may include a second carbon-based material, a second metal, and a second binder, wherein the first binder may include a rubber-based binder, and the second binder may include a non-rubber-based binder.

[0010] According to another concept of the present invention, an all-solid-state battery comprises a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein the negative electrode layer may include a negative electrode current collector, and a negative electrode coating layer on the negative electrode current collector. The negative electrode coating layer may include a carbon-based material, a metal, and a binder, and the negative electrode coating layer may include a first region adjacent to the negative electrode current collector and a second region adjacent to the solid electrolyte layer, wherein the first region may include a rubber-based binder and a non-rubber-based binder, and the second region may include a non-rubber-based binder.

[0011] According to the concept of the present invention, a method for manufacturing an all-solid-state battery may include providing a first negative electrode slurry on an negative electrode substrate to form a first coating layer, providing a second negative electrode slurry on the first coating layer to form a second coating layer, and providing a solid electrolyte slurry on the second coating layer to form a solid electrolyte layer. The first negative electrode slurry may include a first carbon-based material, a first metal, and a first binder, and the second negative electrode slurry may include a second carbon-based material, a second metal, and a second binder, wherein the first binder includes a rubber-based binder, and the second binder may include a non-rubber-based binder.

[0012]

[0013] The anode for an all-solid-state battery according to the present invention may include a first coating layer including a rubber-based binder and a second coating layer including a non-rubber-based binder. The second coating layer suppresses side reactions at the interface between the solid electrolyte layer and the anode, thereby improving the life characteristics and high-rate characteristics of the all-solid-state battery.

[0014] By using the method for manufacturing an all-solid-state battery according to the present invention, an all-solid-state battery having excellent productivity, suppressed side reactions, and improved lifespan and high-rate characteristics can be manufactured.

[0015]

[0016] Figure 1 is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention.

[0017] Figure 2 is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention.

[0018] FIG. 3 and FIG. 4 are a plan view and a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention, respectively.

[0019] Figure 5 is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention.

[0020] FIG. 6 is a cross-sectional view of an all-solid-state battery including a gasket structure according to one embodiment of the present invention.

[0021] Figure 7 is a cross-sectional view of a negative electrode for an all-solid-state battery according to one embodiment of the present invention.

[0022] Figures 8 and 9 are enlarged views of area M of Figure 1.

[0023] Figure 10 is a cross-sectional view of a negative electrode for an all-solid-state battery according to one embodiment of the present invention.

[0024]

[0025] To fully understand the structure and effects of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and subject to various modifications. However, the description of these embodiments is provided solely to ensure a complete disclosure of the present invention and to fully inform those skilled in the art of the invention of the scope of the invention.

[0026] In this specification, when a component is referred to as being on another component, it means that it can be formed directly on the other component, or a third component may be interposed between them. Furthermore, in the drawings, the thicknesses of the components are exaggerated for the sake of clarity. Parts designated by the same reference numerals throughout the specification represent the same components.

[0027] Embodiments described herein will be described with reference to cross-sectional and / or plan views, which are ideal illustrations of the present invention. In the drawings, the thicknesses of films and regions are exaggerated for the purpose of effectively explaining the technical contents. Accordingly, the regions illustrated in the drawings have a schematic nature, and the shapes of the regions illustrated in the drawings are intended to illustrate specific shapes of regions of the device and are not intended to limit the scope of the invention. Although terms such as first, second, and third are used to describe various components in various embodiments of the present specification, these components should not be limited by such terms. These terms are used only to distinguish one component from another. The embodiments described and illustrated herein also include complementary embodiments thereof.

[0028] The terminology used herein is for the purpose of describing embodiments and is not intended to limit the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise. As used herein, the words "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components.

[0029] As used herein, “combination thereof” may mean mixtures, laminates, composites, copolymers, alloys, blends, and reaction products of the components.

[0030] Unless otherwise defined herein, the particle size may be the average particle size. In addition, the particle size refers to the average particle size (D50), which means the diameter of particles with a cumulative volume of 50% by volume in a particle size distribution. The average particle size (D50) can be measured by a method well known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope (TEM) photograph or a scanning electron microscope (SEM) photograph. Alternatively, the average particle size (D50) value can 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 the counted number. Alternatively, the average particle size (D50) value can be obtained by measuring with 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 size (D50) based on 50% of the particle size distribution in the measuring device can be calculated.

[0031] Figure 1 is a cross-sectional view of an all-solid-state battery (10) according to one embodiment of the present invention.

[0032] Referring to FIG. 1, an all-solid-state battery (10) according to one embodiment includes a positive electrode layer (100), a negative electrode layer (200) facing the positive electrode layer (100), and a solid electrolyte layer (300) disposed between the positive electrode layer (100) and the negative electrode layer (200). However, the present invention is not limited thereto, and the all-solid-state battery (10) may further include an additional functional layer, such as an adhesion enhancing layer, disposed between the positive electrode layer (100) and the solid electrolyte layer (300) or between the negative electrode layer (200) and the solid electrolyte layer (300).

[0033] The positive electrode layer (100) of one embodiment includes a positive electrode current collector (110) and a positive electrode active material layer (120) disposed on the positive electrode current collector (110). The positive electrode active material layer (120) may include a positive electrode active material, a solid electrolyte, a conductive material, and a binder.

[0034] The cathode current collector (110) can provide a reference surface on which the cathode active material layer (120) is arranged. The cathode current collector (110) can include a plate or foil including, 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.

[0035] Meanwhile, unlike that illustrated in FIG. 1, in one embodiment of the present invention, the positive electrode current collector (110) may be omitted. Although not illustrated, a carbon layer having a thickness of 0.1 μm to 4 μm may be additionally disposed between the positive electrode current collector (110) and the positive electrode active material layer (120) to increase the bonding strength between the positive electrode current collector (110) and the positive electrode active material layer (120).

[0036] The cathode active material layer (120) may include a cathode active material, a solid electrolyte, a conductive material, and a binder.

[0037] A cathode active material is a material that can reversibly absorb and desorb lithium ions. The cathode active material may include, but is not necessarily limited to, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, and lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide. The cathode active materials may be used alone or as a mixture of two or more.

[0038] Lithium transition metal oxides include, for example, Li a A 1-b B b D2(0.90≤a≤1, 0≤b≤0.5), Li a E 1-b B b O 2-c D c (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05), LiE 2-b B b O 4-c D c (0≤b≤0.5, 0≤c≤0.05), Li a Ni 1-b-c Co b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni 1-b-c Co b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni 1-b-c Mn b B c D α(0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2), Li a Nor 1-b-c Mn b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Nor b E c G d O2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1), Li a Nor b Co c Mn d GeO2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1), Li a NiG b O2(0.9≤a≤1, 0.001≤b≤0.1), Li a CoG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a MnG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a Mn2GbO4(0.90≤a≤1, 0.001≤b≤0.1), QO2, QS2, LiQS2, V2O5, LiV2O5, LiIO2, LiNiVO4, Li 3-f J2(PO4)3(0≤f≤2), Li 3-fA compound represented by any one of Fe2(PO4)3(0≤f≤2), LiFePO4. In these compounds, the capital letter “A” is Ni, Co, Mn, or a combination thereof, the capital letter “B” is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof, the capital letter “D” is O, F, S, P, or a combination thereof, the capital letter “E” is Co, Mn, or a combination thereof, the capital letter “F” is F, S, P, or a combination thereof, the capital letter “G” is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof, the capital letter “Q” is Ti, Mo, Mn, or a combination thereof, the capital letter “I” is Cr, V, Fe, Sc, Y, or a combination thereof, and the capital letter “J” is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0039] The cathode active material may include, for example, a lithium salt of a transition metal oxide having a layered rock salt type structure among the lithium transition metal oxides described above. The "layered rock salt type structure" is, for example, a cubic rock salt type structure. <111> It is a structure in which oxygen atomic layers and metal atomic layers are alternately and regularly arranged in a direction, and thereby each atomic layer forms a two-dimensional plane. The "cubic rock salt structure" refers to a sodium chloride type (NaCl type) structure, which is a type of crystal structure, and specifically refers to a structure in which face-centered cubic lattices (fcc) formed by cations and anions respectively are arranged with a displacement of half of the ridge of the unit lattice. Lithium transition metal oxides having this layered rock salt structure include, for example, LiNi x Co y Al z O2(NCA) or LiNi x Co y Mn zO2(NCM) (0 <x<1,0<y<1, 0<z<1, x+y+z=1) 등의 삼원계 리튬전이금속산화물일 수 있다. 양극활물질이 층상암염형 구조를 갖는 삼원계 리튬전이금속산화물을 포함하는 경우, 전고체 전지(10)의 에너지 밀도가 커지고 열안정성이 향상될 수 있다.

[0040] The above-described compound included in the positive electrode active material may be covered by a coating layer (not shown). The positive electrode active material may also be a mixture of the above-described compound and a compound to which a coating layer is added. Meanwhile, the coating layer added to the surface of the positive electrode active material may include, for example, an oxide, a hydroxide, an oxyhydroxide, an oxycarbonate, or a hydroxycarbonate of the coating elements below. The compound forming the coating layer 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 may include, for example, Li2O-ZrO2 (LZO). The method of forming the coating layer is selected within a range that does not adversely affect the physical properties of the positive electrode active material. The method of forming the coating layer includes, for example, spray coating, dipping, etc.

[0041] When the cathode active material contains nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, for example, the capacity density of the all-solid-state battery (10) can be increased, thereby reducing metal dissolution of the cathode active material in a charged state. As a result, the cycle characteristics of the all-solid-state battery (10) in a charged state are improved. Meanwhile, the “cycle characteristics” are characteristics indicating the degree to which the all-solid-state battery (10) is deteriorated due to charge / discharge of the all-solid-state battery (10). An all-solid-state battery (10) with high cycle characteristics may have a small degree of deterioration of the all-solid-state battery (10) due to charge / discharge, and an all-solid-state battery (10) with low cycle characteristics may have a large degree of deterioration of the all-solid-state battery (10) due to charge / discharge.

[0042] The shape of the cathode active material may include particle shapes such as a sphere or an ellipsoid, for example. The particle size and content of the cathode active material are not particularly limited.

[0043] The solid electrolyte may have a particle shape. The solid electrolyte may be dispersed between the positive electrode active materials. The solid electrolyte may include a sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics. Examples of the sulfide-based solid electrolyte include Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element), 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, n are positive numbers, capital letter “Z” represents Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, capital letter “M” is one of P, Si, Ge, B, Al, Ga In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may include at least one selected from (0≤x≤2).

[0044] Sulfide-based solid electrolytes include, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-xI x It may be an argyrodite-type compound including at least one selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0045] Alternatively, the sulfide-based solid electrolyte is Li 7-a M a PS 6-c X c It may be an argyrodite-type compound containing (0≤a≤2, (0≤c≤2)), where X may be F, Br, Cl, or a combination thereof. M is candium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof. Can be.

[0046] Alternatively, the sulfide-based solid electrolyte may be the same as the solid electrolyte included in the solid electrolyte layer (300) described later.

[0047] The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. Since the argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state battery can be reduced, and the defect of the solid electrolyte membrane being penetrated and short-circuited due to the formation of lithium dendrites can be prevented. The elastic modulus of the solid electrolyte may be, for example, 15 GPa to 35 GPa.

[0048] The solid electrolyte included in the positive electrode active material layer (120) may have a smaller median particle size (D50) than the solid electrolyte included in the solid electrolyte layer (300). For example, the median particle size (D50) of the solid electrolyte included in the positive electrode active material layer (120) may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the median particle size (D50) of the solid electrolyte included in the solid electrolyte layer (300). Meanwhile, the median particle size (D50) may be a median diameter measured using a laser particle size distribution meter.

[0049] The cathode active material layer (120) may include a conductive material. The conductive material may have conductivity without causing a chemical change in the all-solid-state battery (10), thereby increasing the conductivity of the cathode active material and the solid electrolyte.

[0050] The conductive material may include a carbon-based material. The conductive material may include, for example, one or more selected from graphite, carbon black, acetylene black, carbon nanofibers, and carbon nanotubes.

[0051] The positive electrode active material layer (120) may further include a binder. The binder may include a material for binding the positive electrode active material, solid electrolyte, and conductive material included in the positive electrode active material layer (120) and improving bonding strength with the positive electrode current collector (110). The binder may include, for example, polyvinylidene fluoride, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0052] Based on 100 parts by weight of the total of the positive electrode active material, the solid electrolyte, the conductive material, and the binder, the positive electrode active material layer (120) may include 85 parts by weight or more and 92 parts by weight or less of the positive electrode active material. Based on 100 parts by weight of the total of the positive electrode active material, the solid electrolyte, the conductive material, and the binder, the positive electrode active material layer (120) may include 0.5 parts by weight or more and 1.5 parts by weight or less of the binder.

[0053] Based on 100 parts by weight of the solid electrolyte, the positive electrode active material layer (120) may include 1 part by weight or more and 50 parts by weight or less of a conductive material. If the conductive material is included in the positive electrode active material layer (120) in an amount of less than 1 part by weight based on 100 parts by weight of the solid electrolyte, the proportion of the conductive material may decrease, thereby lowering the electrical conductivity of the positive electrode active material layer (120). If the conductive material is included in the positive electrode active material layer (120) in an amount of more than 50 parts by weight based on 100 parts by weight of the solid electrolyte, the proportion of the conductive material may be excessively high, so that a covering layer covering the surface of the solid electrolyte may not be properly formed.

[0054] The cathode active material layer (120) may further include additives such as fillers, coating agents, dispersants, and ion conductive aids in addition to the cathode active material, solid electrolyte, conductive agent, and binder described above.

[0055]

[0056] Referring to FIG. 1, the negative electrode layer (200) may include a negative electrode current collector (210) and a negative electrode coating layer (220) on the negative electrode current collector (210). The negative electrode coating layer (220) may include a first coating layer (221) on the negative electrode current collector (210) and a second coating layer (222) on the first coating layer.

[0057] The negative electrode current collector (210) can provide a reference surface on which the first coating layer (221) is arranged. The negative electrode current collector (210) can include, for example, a material that does not react with lithium, i.e., does not form an alloy or compound with lithium. The material constituting the negative electrode current collector (210) is not necessarily limited to, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), and any material that can be used as an electrode current collector can be used. The thickness of the negative electrode current collector can be 1 to 20 μm, for example, 5 to 15 μm, for example, 7 to 10 μm.

[0058] The negative electrode current collector (210) may be composed of one of the above-described metals, or may include an alloy or coating material of two or more metals. The negative electrode current collector (210) is, for example, in the form of a plate or foil. Meanwhile, in one embodiment, the negative electrode current collector (210) may be omitted.

[0059] The cathode coating layer (220) will be described later with reference to FIG. 7.

[0060] Referring to FIG. 1, a solid electrolyte layer (300) may be provided between the anode layer (100) and the cathode layer (220).

[0061] The solid electrolyte layer (300) may include a sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics. The solid electrolyte in the solid electrolyte layer (300) may be the same as or different from the solid electrolyte included in the positive electrode active material layer (120) described above.

[0062] In one embodiment, the solid electrolyte included in the solid electrolyte layer (300) may be amorphous, crystalline, or a mixture thereof. In addition, the solid electrolyte may be, for example, a sulfide-based solid electrolyte material that includes at least sulfur (S), phosphorus (P), and lithium (Li) as constituent elements. For example, the solid electrolyte may be a material including Li2S-P2S5. When using a sulfide-based solid electrolyte material that includes Li2S-P2S5 to form the solid electrolyte, the mixing molar ratio of Li2S and P2S5 is, for example, in the range of Li2S:P2S5=50:50 to 90:10.

[0063] Sulfide-based solid electrolytes include, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may be an argyrodite-type compound including at least one selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0064] Alternatively, the sulfide-based solid electrolyte is Li 7-a M a PS 6-c X cIt may be an argyrodite-type compound containing (0≤a≤2, 0≤c≤2), where X may be F, Br, Cl, or a combination thereof. M is candium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof. Can be.

[0065] The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. When the argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state battery is reduced, and the defect of the solid electrolyte membrane being penetrated and short-circuited due to the formation of lithium dendrites can be prevented. The elastic modulus of the solid electrolyte is, for example, 15 GPa to 35 GPa.

[0066] The solid electrolyte layer (300) may further include a binder. The binder included in the solid electrolyte layer (300) may be, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, and the like, but is not limited thereto. For example, the binder may include at least one selected from the group consisting of styrene butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polyvinyl alcohol, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate. The binder of the solid electrolyte layer (300) may be the same as or different from the binder included in the positive electrode active material layer (120) or the binder included in the negative electrode active material layer (220).

[0067] In one embodiment of the present invention, the solid electrolyte layer (300) may further include at least one selected from the group consisting of xylene, benzene, toluene, pentane, hexane, cyclohexane, and octyl acetate. The xylene, benzene, toluene, pentane, hexane, cyclohexane, octyl acetate, etc. may be derived from a solvent used in the preparation of the solid electrolyte slurry. In one embodiment, the solid electrolyte layer (300) may further include octyl acetate in addition to the argyrodite-based solid electrolyte and binder. The xylene, etc. may partially penetrate into the negative electrode (200) layer during the process of preparing an all-solid-state battery to be described later.

[0068]

[0069] Figure 2 is a cross-sectional view of an all-solid-state battery (10) according to another embodiment of the present invention.

[0070] Referring to FIG. 2, the solid electrolyte layer (300) may include a first solid electrolyte layer (310) and a second solid electrolyte layer (320). The first solid electrolyte layer (310) may be adjacent to the positive electrode layer (100), and the second solid electrolyte layer (320) may be adjacent to the negative electrode layer (200).

[0071] The first solid electrolyte layer (310) and the second solid electrolyte layer (320) may have different thicknesses. The first solid electrolyte layer (310) may have a first thickness (TK1), and the second solid electrolyte layer (320) may have a second thickness (TK2). The first thickness (TK1) may be greater than the second thickness (TK2). For example, the first thickness (TK1) may be 2 to 100 times greater than the second thickness (TK2).

[0072]

[0073] Fig. 3 is a plan view of an all-solid-state battery (10) according to another embodiment of the present invention. Fig. 4 is a cross-sectional view taken along line A-A' of Fig. 3. In this embodiment, detailed descriptions of technical features overlapping with those previously described with reference to Figs. 1 and 2 will be omitted, and differences will be described in detail.

[0074] Referring to FIGS. 3 and 4, the area of ​​the anode layer (100) and the area of ​​the cathode layer (200) may be different from each other. Specifically, the area of ​​the cathode layer (200) may be larger than the area of ​​the anode layer (100). The anode layer (100) may be completely overlapped within the cathode layer (200).

[0075] In one embodiment of the present invention, the first solid electrolyte layer (310) may have substantially the same area as the positive electrode layer (100). The second solid electrolyte layer (320) may have substantially the same area as the negative electrode layer (200).

[0076] Specifically, the first solid electrolyte layer (310) may have a first width (WI1) in a first direction (D1). The second solid electrolyte layer (320) may have a second width (WI2) in the first direction (D1). The first width (WI1) may be smaller than the second width (WI2). The first solid electrolyte layer (310) may have a third width (WI3) in the second direction (D2). The second solid electrolyte layer (320) may have a fourth width (WI4) in the second direction (D2). The third width (WI3) may be smaller than the fourth width (WI4).

[0077] The all-solid-state battery (10) according to the present embodiment can be manufactured by forming a first laminate of a positive electrode layer (100) and a first solid electrolyte layer (310), forming a second laminate of a negative electrode layer (200) and a second solid electrolyte layer (320), and then laminating the first laminate and the second laminate.

[0078]

[0079] FIG. 5 is a cross-sectional view taken along line A-A' of FIG. 3 to explain an all-solid-state battery according to another embodiment of the present invention.

[0080] Referring to FIG. 5, the negative electrode layer (200) of the all-solid-state battery (10) may further include a lithium metal layer (400) between the negative electrode current collector (210) and the first coating layer (220). The thickness of the lithium metal layer (400) may further increase when the all-solid-state battery (10) is charged. The first coating layer (220) serves as a protective layer for the lithium metal layer (400), and at the same time, may suppress the growth of lithium dendrites from the lithium metal layer (400).

[0081] The lithium metal layer (400) may be a metal thin film containing lithium or a lithium alloy. The lithium alloy may include, but is not limited to, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy, etc., and any lithium alloy may be used. The lithium metal layer (400) may contain one of these alloys or lithium. Alternatively, the lithium metal layer (400) may contain various types of alloys.

[0082] The lithium metal layer (400) may have a fifth width (WI5) in the first direction (D1). The fifth width (WI5) may be equal to or greater than the first width (WI1). The fifth width (WI5) may be equal to or less than the second width (WI2). For example, the fifth width (WI5) may be greater than the first width (WI1) and less than the second width (WI2).

[0083]

[0084] FIG. 6 is a cross-sectional view illustrating an all-solid-state battery according to another embodiment of the present invention.

[0085] Referring to FIG. 6, the all-solid-state battery (10) may include a gasket structure (400). The gasket structure (400) may fill in the step difference in the side surface of the all-solid-state battery (10) caused by the difference in the area of ​​the first laminate and the second laminate. The gasket structure (400) may surround the side surfaces of the first laminate of the all-solid-state battery (10) along the first and second directions (D1, D2). For example, the thickness of the gasket structure (400) may be substantially the same as the thickness of the first laminate. Accordingly, even when the first and second laminates having different areas are laminated and pressed, damage to the step difference in the side surface of the all-solid-state battery can be prevented. The term “substantially the same thickness” may be defined as a thickness that can prevent damage to the step difference in the side surface of the all-solid-state battery even when the first and second laminates having different areas are laminated and pressed.

[0086]

[0087] Hereinafter, the negative electrode for the all-solid-state battery of the present invention will be described in more detail.

[0088] Figure 7 is an enlarged view of a cross-section of a negative electrode (200) for an all-solid-state battery according to one embodiment of the present invention.

[0089] Referring to FIG. 7, the first coating layer (221) may include first composite particles (AM1) and a first binder (BND1). The first composite particles (AM1) included in the first coating layer (221) may have a particle shape. The median particle size average particle diameter (D50) of the first composite particles (AM1) having a particle shape may be, for example, 4 μm or less, 2 μm or less, 1 μm or less, or 900 nm or less. The median particle size average particle diameter (D50) of the first composite particles (AM1) may be, for example, 10 nm to 4 μm, 10 nm to 2 μm, or 10 nm to 900 nm. Since the first composite particles (AM1) have a median particle size average particle diameter (D50) within this range, reversible absorption and / or desorption of lithium may be more easily performed during charge and discharge. Meanwhile, the median particle size (D50) may be the median diameter measured using a laser particle size distribution meter.

[0090] The first composite particle (AM1) may include one selected from among a metal and a metalloid and carbon. For example, the first composite particle (AM1) may be a composite of a first carbon-based material and a first metal.

[0091] The carbonaceous material included in the first composite particle (AM1) may be, in particular, amorphous carbon. Amorphous carbon includes, but is not necessarily limited to, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), and graphene. Amorphous carbon is carbon that has no crystallinity or very low crystallinity, and is distinguished from crystalline carbon or graphitic carbon.

[0092] The metal or metalloid includes, but is not limited to, one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), and may be a metal or metalloid substance that forms an alloy or compound with lithium. On the other hand, nickel (Ni) does not form an alloy with lithium and therefore is not a metal included in the first composite particle (AM1).

[0093] In one embodiment, the first composite particle (AM1) may include a mixture of amorphous carbon and one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The mixing ratio of the mixture of amorphous carbon and gold (Au), etc., may be, for example, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1 by weight, but is not necessarily limited to this range and may be selected according to the required characteristics of the all-solid-state battery (10). When the carbonaceous material and the metal or metalloid have this composition, the cycle characteristics of the all-solid-state battery (10) can be further improved.

[0094] The first binder (BND1) may include a rubber-based binder. The type of the rubber-based binder is not particularly limited, and may include at least one selected from styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR), acrylate butadiene rubber (ABR), methacrylate butadiene rubber, acrylonitrile-butadiene-styrene (ABS) rubber, styrene-butadiene-styrene (SBS) rubber, or a combination thereof. In one embodiment, the first binder may include styrene butadiene rubber (SBR) or nitrile butadiene rubber (NBR).

[0095] The first binder (BND1) may further include a non-rubber binder. For example, the first binder (BND1) may further include at least one selected from the group consisting of polytetrafluoroethylene, carboxymethyl cellulose, polyvinylidene fluoride, polyethylene, polyvinyl alcohol, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0096] In other words, the first binder (BND1) may include both a rubber-based binder and a non-rubber-based binder. For example, the first binder may include styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC).

[0097] When the first binder (BND1) includes both a rubber-based binder and a non-rubber-based binder, the degree of amorphousness of the first binder (BND1) can be controlled by controlling the mixing ratio of the rubber-based binder and the non-rubber-based binder. By controlling the degree of amorphousness of the first binder (BND1), the degree of amorphousness of the first negative electrode slurry including the first binder (BND1) can be controlled, and the flexibility and rollability of the negative electrode layer formed therefrom can be increased.

[0098] In one embodiment, the weight ratio of the rubber-based binder and the non-rubber-based binder included in the first binder (BND1) may be 2:8 to 8:2, or 3:7 to 7:3. When the rubber-based binder and the non-rubber-based binder have the above weight ratio, the first binder (BND1) and the first coating layer (221) manufactured therefrom may have sufficient flexibility.

[0099] Since the first coating layer (221) includes a first binder (BND1) including a rubber-based binder, the first coating layer (221) can be stably formed on the negative electrode current collector (210). That is, the bonding strength between the first coating layer (220) and the negative electrode current collector (210) can be increased. In addition, cracking of the first coating layer (221) is suppressed despite changes in the volume and / or relative position of the first coating layer (221) during the charge and discharge process. When the first coating layer (221) does not include a binder or includes only a non-rubber-based binder, the first coating layer (221) can be easily separated from the negative electrode current collector (210). As the first coating layer (221) is detached from the negative electrode current collector (210), the negative electrode current collector (210) may come into contact with the solid electrolyte layer (300) at the exposed portion, thereby increasing the possibility of a short circuit occurring.

[0100] The first coating layer (221) can be manufactured, for example, by providing a mixture in which the materials constituting the first coating layer (221) are dispersed onto the negative electrode current collector (210). Since the first binder (BND1) is included in the materials constituting the first coating layer (221), stable dispersion of composite particles () in the mixture is possible. For example, when applying the mixture onto the negative electrode current collector (210) by screen printing, it is possible to suppress clogging of the screen (e.g., clogging by aggregates of the negative electrode active material) by the first binder (BND1).

[0101] The content of the first binder (BND1) included in the first coating layer (221) may be 0.2 wt% to 20 wt%, 2 wt% to 15 wt%, or 5 wt% to 10 wt%.

[0102] The first coating layer (221) may further include other additives in addition to the negative electrode active material (AM) and the first binder (BND1). The first coating layer (221) may further include, for example, fillers, coating agents, dispersants, ion conductive additives, etc.

[0103] Referring again to FIG. 7, a second coating layer (222) including second composite particles (AM2) and a non-rubber second binder (BND2) may be disposed on the first coating layer (221).

[0104] The second coating layer (222) is disposed between the first coating layer (221) and the solid electrolyte layer (300) to stabilize the interface between the cathode layer (200) and the solid electrolyte layer (300) and suppress side reactions at the interface. The interface stabilization and side reaction suppression effects of the second coating layer (222) will be described later with reference to FIGS. 8 and 9.

[0105] The second composite particle (AM2) may include one selected from among metals and metalloids and carbon. For example, the second composite particle (AM2) may be a composite of a second carbon-based material and a second metal. The second composite particle (AM2) may be identical to or similar to the first composite particle (AM1) included in the first coating layer (221).

[0106] In one embodiment, the second carbon-based material may be amorphous carbon, such as carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), graphene, or the like. In one embodiment, the second metal may be gold (Au), platinum (Pt), silver (Ag), aluminum (Al), or the like. The weight ratio of the second carbon-based material to the second metal may be, for example, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1.

[0107] The second binder (BND2) included in the second coating layer may be a non-rubber binder. In particular, the second binder may not include a rubber binder. The non-rubber binder is not particularly limited and may include, for example, at least one selected from the group consisting of polytetrafluoroethylene, carboxymethyl cellulose, polyvinylidene fluoride, polyethylene, polyvinyl alcohol, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate. In one embodiment, the second binder (BND2) may include carboxymethyl cellulose, polyvinylidene fluoride, and the like.

[0108] Since the second coating layer (222) includes the second binder (BND2), the second coating layer (222) can be stably formed on the first coating layer (221). That is, the bonding strength between the second coating layer (222) and the first coating layer (221) can be increased.

[0109] The content of the second binder (BND2) included in the second coating layer (222) may be 0.2 wt% to 20 wt%, 2 wt% to 15 wt%, or 5 wt% to 10 wt%.

[0110] The second coating layer may further include, in addition to the second composite particles (AM2) and the second binder (BND2), at least one selected from the group consisting of xylene, benzene, toluene, pentane, hexane, cyclohexane, and octyl acetate. The xylene, etc. may be derived from the solid electrolyte layer (300) formed on the second coating layer (222).

[0111] FIG. 8 is a drawing for showing an anode (200) for an all-solid-state battery according to one embodiment of the present invention, and is an enlarged view of area M of FIG. 1. FIG. 9 is a drawing for showing an anode (200) for an all-solid-state battery according to a comparative example of the present invention, and is an enlarged view of area M of FIG. 1. The anode coating layer (220) of the present invention will be described in more detail with reference to FIGS. 8 and 9.

[0112] The all-solid-state battery according to the present invention can be manufactured by a method of directly applying a solid electrolyte slurry onto a negative electrode (200). In this case, a portion of the solvent of the solid electrolyte slurry can penetrate into the negative electrode coating layer (220) that is in direct contact with the solid electrolyte layer (300) and come into contact with the binder included in the negative electrode coating layer (220).

[0113] Referring to FIG. 9, an all-solid-state battery according to a comparative example of the present invention may include a negative electrode coating layer (220) formed of a single layer. When the negative electrode coating layer (220) includes a first composite particle (AM1) and a first binder (BND1), a solvent derived from a solid electrolyte slurry may come into contact with the first binder (BND1) including a rubber-based binder. The rubber-based binder has a high reactivity with the solvent of the solid electrolyte slurry, particularly octyl acetate, and thus, when in contact with octyl acetate, serious deformation of the binder may occur. In addition, a resistance layer may be formed at the interface between the negative electrode coating layer (220) and the solid electrolyte layer (230) due to a side reaction between the rubber-based binder and octyl acetate, thereby increasing the interfacial resistance.

[0114] Referring to FIG. 8, the cathode layer (200) according to the present invention includes a second coating layer (222) between the solid electrolyte layer (300) and the first coating layer (221), so that a solvent derived from the solid electrolyte slurry can come into contact with the second binder (BND2), which is a non-rubber-based binder. The non-rubber-based binder has lower reactivity with the solvent, particularly octyl acetate, than the rubber-based binder, so that the degree of deformation of the binder can be small. In addition, due to the low reactivity of the non-rubber-based binder, a resistance layer may hardly be formed at the interface between the cathode coating layer (220) and the solid electrolyte layer (300).

[0115] Referring back to FIG. 8, the concentration of the solvent derived from the solid electrolyte slurry may decrease in the opposite direction of the third direction (D3) from the interface between the solid electrolyte layer (300) and the cathode coating layer (220). In particular, the concentration of the solvent may decrease rapidly in the second coating layer (222), so that almost no solvent may exist in the first coating layer (221). In other words, the solvent of the solid electrolyte slurry hardly reaches the first coating layer (221) including the rubber-based binder, so that side reactions and binder deformation problems may not occur.

[0116] The negative electrode layer according to the present invention can suppress side reactions at the interface between the negative electrode layer (200) and the solid electrolyte layer (300) and prevent an increase in interfacial resistance by including a second coating layer that does not include a rubber-based binder. When the interfacial resistance is reduced, the high-rate characteristics of the all-solid-state battery can be improved, and the life characteristics can also be improved as the Coulombic efficiency increases.

[0117] Referring back to FIG. 7, the first coating layer (221) may have a first coating layer thickness (CTK1), and the second coating layer (222) may have a second coating layer thickness (CTK2). The ratio of the first coating layer thickness (CTK1) to the second coating layer thickness (CTK2) may be 10:1 to 1:10, 5:1 to 1:1, or 3:1 to 2:1.

[0118] When the first coating layer thickness (CTK1) and the second coating layer thickness (CTK2) satisfy the thickness ratio as described above, the interfacial resistance at the interface between the cathode layer (200) and the solid electrolyte layer (300) is suppressed, while the cathode layer (200) can have sufficient flexibility.

[0119]

[0120] Fig. 10 is a cross-sectional view showing a negative electrode for an all-solid-state battery according to another embodiment of the present invention.

[0121] Referring to FIG. 10, an anode (200) for an all-solid-state battery according to one embodiment includes a cathode current collector (210) and a cathode coating layer (220) on the cathode current collector (210), wherein the cathode coating layer (220) may include a first region (R1) adjacent to the cathode current collector and a second region (R2) adjacent to the solid electrolyte layer (300).

[0122] The first region (R1) may be defined as a hexahedral space (100 nm*100 nm*100 nm) centered on a point located at a predetermined distance in the third direction (D3) from the negative electrode current collector (210). The predetermined distance may be 100 nm to 10 um. Alternatively, the predetermined distance may be a length corresponding to 0.001 to 0.5 times the total thickness of the negative electrode coating layer (220).

[0123] The second region may be defined as a hexahedral space (100 nm * 100 nm * 100 nm) centered at a point located at a predetermined distance in the third direction (D3) from the interface between the solid electrolyte layer (300) and the cathode (200). The predetermined distance may be 100 nm to 2 um. Alternatively, the predetermined distance may be a length corresponding to 0.001 to 0.1 times the total thickness of the cathode coating layer (220).

[0124] The first region (R1) may include a carbon-based material, a metal, and a first binder (BND1). The first binder (BND1) may include both a rubber-based binder and a non-rubber-based binder. The carbon-based material and the metal may exist in the form of composite particles (AM). The details regarding the rubber-based binder, the non-rubber-based binder, and the composite particles may be the same as or similar to those described with reference to FIGS. 7 to 9.

[0125] For example, the first region (R1) may include composite particles (AM) of amorphous carbon and metal, may include styrene butadiene rubber or nitrile butadiene rubber as a rubber-based binder, and may include carboxymethyl cellulose, polyvinylidene fluoride, etc. as a non-rubber-based binder.

[0126] The second region (R2) may include a carbon-based material, a metal, and a non-rubber binder. That is, the second region (R2) may not include a rubber-based binder. The carbon-based material and the metal may exist in the form of composite particles (AM). The composite particles included in the second region (R2) may be the same as the composite particles included in the first region (R1). The non-rubber binder and the composite particles may be the same as or similar to those described with reference to FIGS. 7 to 9.

[0127] For example, the second region (R2) may include composite particles of amorphous carbon and metal, and may include carboxymethyl cellulose, polyvinylidene fluoride, polyacrylonitrile, or the like as a non-rubber binder.

[0128] The second region (R2) may further comprise a solvent derived from the solid electrolyte layer. For example, the second region may further comprise at least one selected from the group consisting of xylene, benzene, toluene, pentane, hexane, cyclohexane, and octyl acetate. In one embodiment, the first region may further comprise octyl acetate in addition to the composite particles and the non-rubber binder.

[0129] Since the second region (R2) contains only a non-rubber-based binder with low reactivity with the solvent, side reactions between the solvent and the binder derived from the solid electrolyte may hardly occur. Accordingly, the resistance at the interface between the solid electrolyte layer (300) and the cathode layer (200) may be reduced.

[0130] According to another embodiment of the present invention, the content of the rubber-based binder included in the first region (R1) may be 100 times or more the content of the rubber-based binder included in the second region (R2). For example, the content of the rubber-based binder in the first region (R1) may be 1000 times or more, or 10000 times or more, the content of the rubber-based binder in the second region (R2). The content of the rubber-based binder may refer to the total weight of the rubber-based binder included in the first region (R1) and the total weight of the rubber-based binder included in the second region (R2).

[0131] According to another embodiment of the present invention, the content of the non-rubber binder included in the first region (R1) may be less than the content of the non-rubber binder included in the second region (R2). For example, the content of the non-rubber binder included in the first region (R1) may be 0.5 to 0.99 times or 0.7 to 0.9 times the content of the non-rubber binder included in the second region (R2). The content of the non-rubber binder may refer to the total weight of the non-rubber binder included in the first region (R1) and the total weight of the non-rubber binder included in the second region (R2).

[0132]

[0133] Hereinafter, a method for manufacturing an all-solid-state battery according to an embodiment will be described. The method for manufacturing an all-solid-state battery according to an embodiment may include providing a first negative electrode slurry on an negative electrode substrate to form a first coating layer, providing a second negative electrode slurry on the first coating layer to form a second coating layer, and providing a solid electrolyte slurry on the second coating layer to form a solid electrolyte layer.

[0134] The first negative electrode slurry may include a first carbon-based material, a first metal, and a first binder. The description of the first carbon-based material, the first metal, and the first binder included in the first negative electrode slurry may be the same as that described in FIG. 7. In one embodiment, the first binder may include styrene butadiene rubber or nitrile butadiene rubber. The first binder may further include at least one selected from the group consisting of polytetrafluoroethylene, carboxymethyl cellulose, polyvinylidene fluoride, polyethylene, polyvinyl alcohol, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0135] A second coating layer can be formed by providing a second cathode slurry on the first coating layer. The second cathode slurry can be formed on the dried first coating layer or on the undried first coating layer. The second coating layer can be applied thinner than the first coating layer. In one embodiment, the ratio of the thickness of the first coating layer to the thickness of the second coating layer can be 10:1 to 1:10, 5:1 to 1:1, or 3:1 to 2:1.

[0136] The second negative electrode slurry may include a second carbon-based material, a second metal, and a second binder. The description of the second carbon-based material, the second metal, and the second binder included in the second negative electrode slurry may be the same as that described in FIG. 7. In one embodiment, the first binder may include at least one selected from the group consisting of polytetrafluoroethylene, carboxymethyl cellulose, polyvinylidene fluoride, polyethylene, polyvinyl alcohol, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate. The second negative electrode slurry may not include a rubber-based binder.

[0137] A negative electrode plate can be manufactured by drying and rolling a laminate including a negative electrode substrate, a first coating layer, and a second coating layer.

[0138] A solid electrolyte slurry can be provided on the manufactured negative electrode plate. The solid electrolyte slurry can be manufactured by adding a binder and a sulfide-based solid electrolyte to a solvent and mixing them.

[0139] Sulfide-based solid electrolytes include, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I xIt may be an argyrodite-type compound including at least one selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0140] The solvent of the solid electrolyte slurry may be an organic solvent. For example, the solvent may include at least one selected from the group consisting of xylene, benzene, toluene, pentane, hexane, cyclohexane, and octyl acetate. In one embodiment, the organic solvent may be octyl acetate.

[0141] A solid electrolyte layer can be manufactured by drying a solid electrolyte slurry. During the drying process, most of the solvent in the solid electrolyte slurry is removed, but some of the solvent may remain in the solid electrolyte layer. In addition, during the process of directly applying the solid electrolyte slurry to the negative electrode, the solvent in the solid electrolyte slurry may penetrate into the second coating layer, and some of the solvent may remain in the second coating layer even after the slurry drying process. The remaining solid electrolyte slurry solvent may contact the second binder within the second coating layer.

[0142] Even when the residual solvent comes into contact with the second binder, since the second binder does not contain a rubber-based binder, side reactions are minimal and interfacial resistance can be reduced. Furthermore, the reduced interfacial resistance can improve the high-rate characteristics and cycle life of the all-solid-state battery.

[0143]

[0144] Example 1

[0145] (Manufacturing of cathode)

[0146] A 10 ㎛ thick SUS foil was prepared as a negative electrode collector. Carbon black (CB) with a primary particle diameter of approximately 30 nm and silver (Ag) particles with an average particle diameter of approximately 60 nm were prepared as composite particle raw materials.

[0147] A mixed powder containing carbon black (CB) and silver (Ag) particles in a weight ratio of 3:1 was added to distilled water as a solvent, and a binder solution containing 3 wt% and 6 wt% of SBR binder and CMC binder, respectively, was added to prepare a mixed solution. The mixed solution was stirred to prepare a first negative electrode slurry. The weight ratio of the mixed powder and the binder in the prepared first negative electrode slurry was 91.74:8.26. The first negative electrode slurry was applied to a SUS sheet using a bar coater and dried in the air at 80°C for 10 minutes to prepare a negative electrode current collector-first coating layer laminate.

[0148] A mixed powder containing carbon black (CB) and silver (Ag) particles in a weight ratio of 3:1 was added to distilled water as a solvent, and a binder solution containing only 6 wt% of CMC binder was added thereto to prepare a mixed solution. The mixed solution was stirred to prepare a second negative electrode slurry. The weight ratio of the mixed powder and the binder in the prepared second negative electrode slurry was 92:8. The second negative electrode slurry was applied onto the first coating layer using a bar coater to form a second coating layer. Thereafter, the negative electrode laminate was prepared by drying in the air at 80°C for 10 minutes and then vacuum drying at 40°C for 10 hours.

[0149] In the manufactured cathode, the thickness of the first coating layer was 15 um and the thickness of the second coating layer was 5 um.

[0150] (Manufacturing of cathode-solid electrolyte subassembly)

[0151] Li6PS5Cl solid electrolyte in the form of argyrodite crystals (D 50 =3.0), a mixture was prepared by adding 1.5 parts by weight of an acrylic binder to 98.5 parts by weight of the solid electrolyte. Octyl acetate was added to the prepared mixture and stirred to prepare a solid electrolyte slurry.

[0152] A solid electrolyte slurry was applied onto the above-mentioned cathode laminate and pre-coated to manufacture a cathode-solid electrolyte sub-assembly.

[0153] (Polar electrode manufacturing)

[0154] Carbon-coated aluminum foil was prepared as a cathode current collector, and LiNi0.8Co0 was prepared as a cathode active material. 15 Mn0. 05 O2 (NCM) powder was prepared. An octyl acetate solution was prepared as a solvent, and a crystalline argyrodite-based solid electrolyte (Li6PS5Cl) was prepared as a solid electrolyte. A PVDF binder (#9300 from Kureha) was prepared as a binder. Carbon nanotubes (CNT) were prepared as a conductive material. These materials were mixed in a weight ratio of positive electrode active material: solid electrolyte: conductive material: binder = 85:13.44:0.56:1, and the mixture was formed into a large sheet shape to manufacture a positive electrode sheet. The manufactured positive electrode sheet was pressed onto a positive electrode current collector to manufacture a positive electrode layer.

[0155] (All-solid-state battery manufacturing)

[0156] A cathode layer was laminated on the cathode-solid electrolyte subassembly manufactured as described above. The laminate was sealed in a pouch shape and subjected to warm isostatic pressing (WIP) at a high temperature of 80°C and 500 MPa for 30 minutes to manufacture an all-solid-state battery.

[0157]

[0158] Example 2

[0159] A negative electrode and an all-solid-state battery were manufactured in the same manner as in Example 1, except that a PVDF binder was used instead of CMC as a binder when manufacturing the second negative electrode slurry.

[0160]

[0161] Example 3

[0162] A negative electrode and an all-solid-state battery were manufactured in the same manner as in Example 1, except that an acrylate binder was used instead of CMC as a binder when manufacturing the second negative electrode slurry.

[0163]

[0164] Comparative Example 1

[0165] An anode and an all-solid-state battery were manufactured in the same manner as in Example 1, except that a cathode was manufactured with only a first coating layer without forming a second coating layer during the manufacture of the cathode.

[0166]

[0167] Comparative Example 2

[0168] A negative electrode and an all-solid-state battery were manufactured in the same manner as in Example 1, except that no binder was used in the manufacture of the second negative electrode slurry.

[0169]

[0170] Comparative Example 3

[0171] A negative electrode and an all-solid-state battery were manufactured in the same manner as in Example 1, except that an SBR binder was used instead of CMC as a binder when manufacturing the second negative electrode slurry.

[0172]

[0173] Comparative Example 4

[0174] A negative electrode and an all-solid-state battery were manufactured in the same manner as in Example 1, except that an NBR binder was used instead of CMC as a binder when manufacturing the second negative electrode slurry.

[0175]

[0176] Evaluation Example 1: Binder Characteristics Evaluation

[0177] When in contact with octyl acetate, a solvent for solid electrolyte slurry, the weight increase rate for each binder was measured and shown in Table 1 below.

[0178] The weight gain rate was calculated according to the following mathematical formula 1.

[0179]

[0180] <Mathematical Formula 1>

[0181] Weight increase rate [%] = [Binder weight after contact with solvent / Initial binder weight] × 100

[0182]

[0183] Weight increase rate (%)SBR650NBR480Acrylate180CMC15PVDF37

[0184] Referring to Table 1, it can be confirmed that the rubber-based binders SBR and NBR have a greater weight increase rate after contact with octyl acetate compared to non-rubber-based binders.

[0185]

[0186] Evaluation Example 2: High-rate characteristics of all-solid-state batteries

[0187] All-solid-state batteries manufactured according to Examples 1 to 3 and Comparative Examples 1 to 4 were charged and discharged once at each C-rate of 0.1 C, 0.33 C, and 1 C, and the rate characteristics were evaluated by calculating the capacity ratio at each C-rate with respect to the 0.1 C discharge capacity. The results are shown in Table 2 below.

[0188]

[0189] First coating layerBinderSecond coating layerBinderRatio characteristics(%)0.1C0.33C1.0CExample 1SBR / CMCCMC100%94%85%Example 2SBR / CMCPVDF100%93%86%Example 3SBR / CMCAcrylate100%93%84%Comparative example 1SBR / CMCSecond coating layerx100%92%80%Comparative example 2SBR / CMCBinder x100%78%54%Comparative example 3SBR / CMCSBR100%91%80%Comparative example 4SBR / CMCNBR100%92%79%

[0190] Referring to Table 2, it can be confirmed that the all-solid-state batteries (Examples 1 to 3) including a non-rubber-based binder in the second coating layer have better rate characteristics compared to the all-solid-state batteries according to the comparative examples.

[0191]

[0192] Evaluation Example 3: All-solid-state battery life characteristics

[0193] The life characteristics of the all-solid-state batteries manufactured according to Examples 1 to 3 and Comparative Examples 1 to 4 were evaluated. The life characteristics were evaluated by the following charge-discharge test. The charge-discharge test was performed by placing the all-solid-state batteries in a 45°C constant-temperature chamber.

[0194] The first cycle was performed by charging the battery at a constant current of 0.33C for approximately 3 hours until the battery voltage reached 4.25 V, then charging at a constant voltage of 0.1 C at 4.25 V, followed by a 10-minute rest period, and then discharging at a constant current of 0.33 C for approximately 3 hours until the battery voltage reached 2.5 V, followed by a 10-minute rest period.

[0195] After the second cycle, charging and discharging were performed up to 100 cycles under the same conditions as the first cycle. The life characteristics are shown in Table 3 below. In Table 3, the capacity retention rate is calculated using the following mathematical equation 2.

[0196] <Mathematical Formula 2>

[0197] Capacity retention rate [%] = [Discharge capacity at the 100th cycle / Discharge capacity at the 1st cycle] × 100

[0198]

[0199] First coating layer binder Second coating layer binder Capacity retention rate (%) Example 1 SBR / CMCCMC85 Example 2 SBR / CMCPVDF87 Example 3 SBR / CMCAcrylate86 Comparative Example 1 SBR / CMCSecond coating layer x81 Comparative Example 2 SBR / CMCBinder x54 Comparative Example 3 SBR / CMCSBR79 Comparative Example 4 SBR / CMCNBR80

[0200] Referring to Table 3, it can be confirmed that the all-solid-state batteries according to the examples have a better capacity retention rate compared to the all-solid-state batteries according to the comparative examples.

[0201]

[0202] Evaluation Example 4: All-solid-state battery resistance characteristics

[0203] The resistance characteristics of the all-solid-state batteries manufactured according to Examples 1 to 3 and Comparative Examples 1 to 4 were evaluated, and the results are shown in Table 4 below. The resistance characteristics were evaluated by the following charge-discharge test.

[0204] After charging at 0.1C, 4.25V, and 0.05C cut-off conditions using constant current-constant voltage (CC-CV), a 10-minute rest period was followed by sequential steps of 0.1C 3.75V discharge, 2-hour rest, and 0.33C 30-second discharge. The resistance value was calculated using the following mathematical equation (3).

[0205] <Mathematical Formula 3>

[0206] DC-IR(Ω) = [(OCV after 2 hours of rest - Voltage after 10 seconds of applying 0.33C constant current)] / (0.33C current value)

[0207]

[0208] First coating layerBinderSecond coating layerBinderResistance (Ω)Example 1SBR / CMCCMC1.45Example 2SBR / CMCPVDF1.27Example 3SBR / CMCAcrylate1.41Comparative Example 1SBR / CMCSecond coating layer x1.62Comparative Example 2SBR / CMCBinder x3.57Comparative Example 3SBR / CMCSBR1.58Comparative Example 4SBR / CMCNBR1.65

[0209] Referring to Table 4, it can be confirmed that the all-solid-state batteries according to the examples have a smaller resistance value compared to the all-solid-state batteries according to the comparative examples.

Claims

1. Including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, The cathode layer includes a cathode current collector, a first coating layer on the cathode current collector, and a second coating layer on the first coating layer, The first coating layer comprises a first carbon-based material, a first metal, and a first binder, The second coating layer includes a second carbon-based material, a second metal, and a second binder, An all-solid-state battery wherein the first binder comprises a rubber-based binder and the second binder comprises a non-rubber-based binder.

2. In paragraph 1, An all-solid-state battery wherein the first binder comprises any one selected from styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR), acrylate butadiene rubber (ABR), methacrylate butadiene rubber, acrylonitrile-butadiene-styrene (ABS) rubber, styrene-butadiene-styrene (SBS) rubber, or a combination thereof.

3. In paragraph 1, An all-solid-state battery wherein the first binder comprises at least one of styrene butadiene rubber (SBR) and nitrile butadiene rubber (NBR).

4. In paragraph 1, An all-solid-state battery wherein the first binder further comprises a non-rubber binder.

5. In paragraph 1, An all-solid-state battery, wherein the second binder comprises at least one selected from the group consisting of polytetrafluoroethylene, carboxymethyl cellulose, polyvinylidene fluoride, polyethylene, polyvinyl alcohol, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

6. In paragraph 1, An all-solid-state battery wherein the content of the first binder in the first coating layer is 0.2 wt% to 20 wt%.

7. In paragraph 1, An all-solid-state battery wherein the content of the second binder in the second coating layer is 0.2 wt% to 20 wt%.

8. In paragraph 1, An all-solid-state battery in which the ratio of the thickness of the second coating layer to the thickness of the first coating layer is 3:1 to 1:

1.

9. In paragraph 1, The solid electrolyte layer is an all-solid-state battery comprising a solid electrolyte, a binder, and octyl acetate.

10. In paragraph 9, An all-solid-state battery wherein the second coating layer further comprises octyl acetate.

11. In paragraph 9, The above solid electrolyte is Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), Li 7-x PS 6-x I x (0≤x≤2), and Li 7-y M1 y PS 6-z M2 z Including one or more selected from among The above M1 is one or more elements selected from groups 3 to 15 of the periodic table, The above M2 is one or more elements selected from group 17 of the periodic table, 0≤y≤2, and 0≤z≤2, All-solid-state battery.

12. Including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, The above negative electrode layer includes a negative electrode current collector and a negative electrode coating layer on the negative electrode current collector, The above cathode coating layer includes a carbon-based material, a metal, and a binder, The cathode coating layer includes a first region adjacent to the cathode current collector and a second region adjacent to the solid electrolyte layer, The first region includes a rubber-based binder and a non-rubber-based binder, The second region is an all-solid-state battery comprising a non-rubber binder.

13. In paragraph 12, The second region is an all-solid-state battery further comprising octyl acetate.

14. Providing a first cathode slurry on a cathode substrate to form a first coating layer; Providing a second cathode slurry on the first coating layer to form a second coating layer; and Comprising providing a solid electrolyte slurry on the second coating layer to form a solid electrolyte layer, The first cathode slurry comprises a first carbon-based material, a first metal, and a first binder, The second cathode slurry comprises a second carbon-based material, a second metal, and a second binder, A method for manufacturing an all-solid-state battery, wherein the first binder comprises a rubber-based binder and the second binder comprises a non-rubber-based binder.

15. In paragraph 14, The above solid electrolyte slurry is a method for manufacturing an all-solid-state battery comprising a solid electrolyte, a binder, and octyl acetate.

16. In paragraph 15, The above solid electrolyte is Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), Li 7-x PS 6-x I x (0≤x≤2), and Li 7-y M1 y PS 6-z M2 z Including one or more selected from among The above M1 is one or more elements selected from groups 3 to 15 of the periodic table, The above M2 is one or more elements selected from group 17 of the periodic table, 0≤y≤2, and 0≤z≤2, All-solid-state battery.

17. In paragraph 14, A method for manufacturing an all-solid-state battery, wherein the first binder comprises at least one of styrene butadiene rubber (SBR) and nitrile butadiene rubber (NBR).

18. In paragraph 14, A method for manufacturing an all-solid-state battery, wherein the first binder further includes a non-rubber binder.

19. In paragraph 14, A method for manufacturing an all-solid-state battery, wherein the second binder comprises at least one selected from the group consisting of polytetrafluoroethylene, carboxymethyl cellulose, polyvinylidene fluoride, polyethylene, polyvinyl alcohol, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

20. In paragraph 14, Each of the first and second carbonaceous materials is crystalline carbon, amorphous carbon, or a combination thereof, A method for manufacturing an all-solid-state battery, wherein each of the first and second metals comprises at least one selected from the group consisting of Ag, Zn, Al, Sn, Mg, Ge, Cu, In, Ni, Bi, Au, Si, Pt, and Pd.

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