All solid-state battery and all solid-state battery stack

Abstract

The present invention relates to an all solid-state battery and an all solid-state battery stack, the all solid-state battery comprising: a negative electrode including a negative electrode protective layer, a negative electrode coating layer, and a negative electrode current collector positioned between the negative electrode protective layer and the negative electrode coating layer; a positive electrode; and a solid electrolyte layer positioned between the negative electrode and the positive electrode.

Description

All-solid-state batteries and all-solid-state battery stacks

[0001] It relates to all-solid-state batteries and all-solid-state battery stacks.

[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 an all-solid-state battery and an all-solid-state battery stack that can effectively suppress the reaction between an electrolyte and a current collector and exhibit excellent battery characteristics.

[0005] One embodiment provides an all-solid-state battery comprising: a cathode including a cathode protective layer, a cathode coating layer, and a current collector positioned between the cathode protective layer and the cathode coating layer; a cathode; and a solid electrolyte layer positioned between the cathode and the cathode.

[0006] Another embodiment provides an all-solid-state battery stack comprising: a first unit cell including a first cathode, a first anode, and a first solid electrolyte layer positioned between the first cathode and the first anode; a second unit cell including a second cathode, a second anode, and a second solid electrolyte layer positioned between the second cathode and the second anode; and an elastic layer positioned between the first unit cell and the second unit cell, wherein the first cathode includes a first cathode coating layer, a first cathode current collector, and a first cathode protective layer, and the second cathode includes a second cathode coating layer, a second cathode current collector, and a second cathode protective layer, and wherein the elastic layer is positioned between the first cathode protective layer and the second cathode protective layer.

[0007] An all-solid-state battery and an all-solid-state battery stack according to an embodiment can effectively suppress the reaction between a current collector and an electrolyte, thereby exhibiting excellent battery characteristics.

[0008] Figure 1 is a schematic drawing of an all-solid-state battery negative electrode according to one embodiment.

[0009] Figure 2 is a cross-sectional view schematically showing an all-solid-state battery according to one embodiment.

[0010] Figure 3 is a cross-sectional view schematically showing an all-solid-state battery stack according to one embodiment.

[0011] Figure 4 is a photograph of a current collector after charge and discharge of an all-solid-state battery manufactured according to Examples 1 to 3 and Comparative Examples 1 and 2.

[0012] Figure 5 is a graph showing the cyclic current results for the negative electrode for the all-solid-state battery of Example 1.

[0013] Figure 6 is a graph showing the cyclic current results for the negative electrode for the all-solid-state battery of Example 2.

[0014] Figure 7 is a graph showing the cyclic current results for the negative electrode for the all-solid-state battery of Example 3.

[0015] Figure 8 is a graph showing the cyclic current results for the negative electrode for the all-solid-state battery of Example 4.

[0016] Figure 9 is a graph showing the cyclic current results for the negative electrode for the all-solid-state battery of Example 5.

[0017] Figure 10 is a graph showing the cyclic current results for the negative electrode for the all-solid-state battery of Example 6.

[0018] Figure 11 is a graph showing the results of the cyclic current for the negative electrode for the all-solid-state battery of Comparative Example 1.

[0019] Figure 12 is a graph showing the results of the cyclic current for the negative electrode for the all-solid-state battery of Comparative Example 2.

[0020] Figure 13 is a graph showing the results of the cyclic current for the negative electrode for the all-solid-state battery of Comparative Example 3.

[0021] 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.

[0022] 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.

[0023] “Combination of these” means a mixture, laminate, composite, copolymer, alloy, blend, reaction product, etc. of the components.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] Throughout this specification, the description of “A and / or B” means “A or B or both.”

[0028] Unless otherwise specified herein, when a part such as a layer, film, region, or plate is said to be “on top of” another part, this includes not only cases where it is “directly on top of” the other part, but also cases where there is another part in between.

[0029] 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.

[0030] "Thickness" may be measured, for example, from photographs taken with an optical microscope such as a scanning electron microscope.

[0031] An all-solid-state battery according to one embodiment includes a cathode including a cathode protective layer, a cathode coating layer, and a cathode current collector positioned between the cathode protective layer and the cathode coating layer; a cathode; and a solid electrolyte layer positioned between the cathode and the anode.

[0032] FIG. 1 schematically illustrates the structure of an anode in an all-solid-state battery according to one embodiment, wherein an anode (400) according to one embodiment includes a cathode protection layer (405), a cathode current collector (401), and a cathode coating layer (403). In this way, the anode according to one embodiment is formed with a cathode protection layer, a cathode current collector, and a cathode coating layer in that order.

[0033] The above-described negative electrode protective layer is positioned on one side of the negative electrode current collector, particularly on the side opposite to the side where the negative electrode active material layer is formed (hereinafter referred to as the “lower side”), and can prevent the negative electrode current collector from being exposed to the outside. Accordingly, contact between the negative electrode current collector and the electrolyte can be suppressed during charging and discharging of the all-solid-state battery, and thus side reactions between the negative electrode current collector and the electrolyte can be prevented.

[0034] According to one embodiment, the cathode protective layer is an insulating layer and substantially exhibits an electrical conductivity of 0. Since the cathode protective layer is an insulating layer, when charging and discharging an all-solid-state battery, the cathode protective layer does not participate in an electrochemical reaction, and can only effectively play a role of physically preventing the area where the cathode current collector is exposed to the outside, for example, reacts with the electrolyte. If the cathode protective layer is a conductive layer having electrical conductivity, the cathode protective layer may also participate in an electrochemical reaction, which may cause corrosion of the cathode current collector, and is therefore not suitable.

[0035] In addition, since the cathode protective layer is an insulating layer, if this cathode protective layer is located between the cathode current collector and the cathode active material layer, the battery operation is impossible, which is not appropriate.

[0036] According to one embodiment, the cathode protective layer may include a fluorine-based adhesive, an acrylic adhesive, a cyanoacrylate-based adhesive, a rubber-based adhesive, a polyurethane-based adhesive, a silicone-based adhesive, or a combination thereof.

[0037] The above fluorinated adhesive may be polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene, or a combination thereof. In addition, the acrylic adhesive may be polyacrylic acid, polymethyl acrylate, polybutyl acrylate, polymethylmethaacrylate, poly(ethylene-co-methyl acrylate), or a combination thereof. The cyanoacrylate adhesive may be polymethyl cyanoacrylate, polyethyl cyanoacrylate, polybutyl cyanoacrylate, polyoctyl cyanoacrylate, or a combination thereof, and the rubber adhesive may be polyisoprene, styrene-butadiene rubber, neoprene, or a combination thereof. There are. The polyurethane adhesive may be 4,4'-, 2,4'- or 2,2'-dicyclohexyl methane diisocyanate or a mixture thereof; 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane or a mixture thereof; 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 2,5- or 2,6-bis(isocyanatomethyl)norbornane or a mixture thereof, or a combination thereof, and the silicone adhesive may be polymethyl siloxane, polymethyl phenyl siloxane, trimethylsilyl-terminated-polymethylsiloxane (PDMS), or a combination thereof.

[0038] In one embodiment, the thickness of the cathode protective layer may be 0.1 μm to 30 μm, 0.2 μm to 20 μm, 0.2 μm to 10 μm, 0.5 μm to 8 μm, or 1 μm to 5 μm. When the thickness of the cathode protective layer is within the above range, side reactions between the cathode current collector and the electrolyte during charge and discharge can be more effectively suppressed without lowering the energy density.

[0039] In one embodiment, the negative current collector may be copper (Cu). Copper current collectors are economical and can be made thin (e.g., 5 μm to 10 μm thick), thereby improving the energy density of all-solid-state batteries.

[0040] In addition, although a copper current collector may cause a side reaction with the electrolyte, the negative electrode according to one embodiment includes a negative electrode protective layer at the bottom of the current collector that can prevent a side reaction between the current collector and the electrolyte, so that only the advantages of the copper current collector can be effectively obtained without such a side reaction problem.

[0041] In one embodiment, the negative electrode coating layer refers to a layer that helps lithium ions released from the positive electrode active material during charge / discharge of an all-solid-state battery to move toward the negative electrode and be deposited on the surface of the current collector. That is, a lithium deposition layer is formed between the negative electrode current collector and the negative electrode coating layer due to the deposition of lithium ions, and the lithium deposition layer functions as a negative electrode active material. Such a negative electrode is generally referred to as a deposition-type negative electrode. The metal and carbon-based materials included in the negative electrode coating layer do not function as a negative electrode active material that directly participates in the charge / discharge reaction. Such a deposition-type negative electrode refers to a negative electrode that does not include a negative electrode active material when the battery is assembled, but in which the lithium deposition layer functions as a negative electrode active material.

[0042] The above cathode coating layer may include a metal and carbon-based material that act as a catalyst.

[0043] In the above cathode coating layer, for example, a metal may be supported on a carbon-based material, or a metal and a carbon-based material may be present in a mixture.

[0044] The carbonaceous material may be, for example, crystalline carbon, amorphous carbon, or a combination thereof, and may be amorphous carbon. The crystalline carbon may be, for example, natural graphite, artificial graphite, mesophase carbon microbeads, carbon nanotubes, graphene, or a combination thereof. The crystalline carbon may be in the form of amorphous, plate-like, flake-like, spherical, or fibrous particles. The amorphous carbon may be, for example, carbon black, acetylene black, Denka black, Ketjen black, furnace black, activated carbon, graphene, or a combination thereof. An example of the carbon black is Super P (Timcal). The amorphous carbon is not limited thereto, and any material classified as amorphous carbon in the relevant field may be used.

[0045] 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.

[0046] 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.

[0047] In one embodiment, the particle size of the primary particles may be 20 nm or more, 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, 70 nm or more, 80 nm or more, or 90 nm or more, and may be 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, or 30 nm or less.

[0048] In one embodiment, the particle size of the secondary particles may be 1 µm or more, 3 µm or more, 5 µm or more, 7 µm or more, 10 µm or more, or 15 µm or more, and may be 20 µm or less, 15 µm or less, 10 µm or less, 7 µm or less, 5 µm or less, or 3 µm or less.

[0049] 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.

[0050] The above metal may be Ag, Au, Sn, Zn, Al, Mg, Ge, Cu, In, Ni, Bi, Pt, Pd or a combination thereof. As the cathode coating layer includes the above metal, the electrical conductivity of the cathode can be further improved.

[0051] The metal may be a nanoparticle, and the size of the metal nanoparticle may be, for example, an average size of 5 nm to 80 nm, but a nanometer size may be suitably used. By using the metal nanoparticle having such a nano size, the battery characteristics (e.g., life characteristics) of the all-solid-state battery can be improved. If the metal particle size increases to the micrometer level, the uniformity of the metal particles in the negative electrode coating layer decreases, so that the current density in a specific region increases and the cycle life characteristics may deteriorate, which is not suitable.

[0052] In one embodiment, the content of the metal may be 3 wt% to 30 wt%, 4 wt% to 25 wt%, 5 wt% to 20 wt%, or 5 wt% to 15 wt% relative to 100 wt% of the total weight of the cathode coating layer.

[0053] Additionally, the carbon-based material may be present in an amount of 70 wt% to 97 wt%, 75 wt% to 96 wt%, 80 wt% to 95 wt%, or 85 wt% to 95 wt% relative to 100 wt% of the total weight of the cathode coating layer.

[0054] The above cathode coating layer may further include a binder. The binder may be a non-aqueous binder.

[0055] 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.

[0056] The binder may be present in an amount of 1 wt% to 15 wt% relative to 100 wt% of the total cathode coating layer. For example, the binder may be present in an amount of 1 wt% to 14 wt%, 1 wt% to 10 wt%, 1 wt% to 7 wt%, or 1 wt% to 5 wt% relative to 100 wt% of the total cathode coating layer.

[0057] When the cathode coating layer further includes a binder, the mixing content of the metal and the carbon-based material can be adjusted according to the binder content, and at this time, the mixing ratio of the metal and the carbon-based material can be adjusted to a weight ratio of 1:40 to 1:1, 1:20 to 1:2, 1:10 to 1:2, or 1:5 to 1:2.

[0058] When the above binder is included in the negative electrode coating layer of the all-solid-state battery in the above content range, the electrical resistance and adhesive strength can be improved, thereby improving the characteristics (battery capacity and output characteristics) of the all-solid-state battery.

[0059] The thickness of the cathode coating layer may be 1 µm to 20 µm. For example, the thickness of the cathode coating layer may be 1 µm or more, 3 µm or more, 5 µm or more, 20 µm or less, 18 µm or less, 16 µm or less, 14 µm or less, 12 µm or less, or 10 µm or less.

[0060] The current collector may be, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li) or an alloy thereof, and may be in the form of a foil or sheet. The thickness of the negative electrode current collector may be 1 μm to 20 μm, 5 μm to 15 μm, or 7 μm to 10 μm.

[0061] 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.

[0062] 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.

[0063] According to one embodiment, the negative electrode may further include a lithium-containing layer formed during initial charging after battery manufacturing, between the negative electrode current collector and the negative electrode coating layer. The thickness of the lithium-containing layer may be 1 µm to 1000 µm, 1 µm to 500 µm, 1 µm to 200 µm, 1 µm to 150 µm, 1 µm to 100 µm, or 1 µm to 50 µm. When the thickness of the lithium-containing layer is within the above range, it may be advantageous in that it can appropriately perform the role of a lithium storage tank and further improve the lifespan.

[0064] The lithium-containing layer can be formed when lithium ions are released from the positive electrode active material during charging after the battery is manufactured, pass through the solid electrolyte, and move toward the negative electrode, resulting in lithium being precipitated and deposited on the negative electrode current collector.

[0065] The above charging process may be a chemical reaction process performed once to three times at 0.05C to 1C at about 25°C to 50°C. When lithium is precipitated and deposited to form a lithium-containing layer, the lithium contained in the lithium-containing layer is ionized and moves toward the positive electrode during discharge, so that the lithium can be used as an anode active material.

[0066] In one embodiment, since the lithium-containing layer is positioned between the current collector and the negative electrode coating layer, the negative electrode coating layer can serve as a protective layer for the lithium-containing layer, thereby inhibiting the precipitation and growth of lithium dendrites. This can suppress short-circuiting and capacity degradation of the all-solid-state battery, and consequently improve the cycle life of the all-solid-state battery.

[0067] Solid electrolyte layer

[0068] In one embodiment, the solid electrolyte layer may include a solid electrolyte. The solid electrolyte may be a sulfide-based solid electrolyte. Sulfide-based solid electrolytes have superior ionic conductivity compared to other solid electrolytes, such as oxide-based solid electrolytes, and may exhibit superior lifespan characteristics over a wider operating range.

[0069] However, the sulfide-based solid electrolyte may cause a problem of penetrating into the negative electrode during charging and discharging of the all-solid-state battery and reacting with the negative electrode current collector. Therefore, stainless steel, which is expensive and difficult to make into a thin film due to lack of electrochemical reactivity with the sulfide-based solid electrolyte, thus reducing the energy density, has been used as the negative electrode current collector. However, in the all-solid-state battery according to one embodiment, as described above, since the negative electrode includes a negative electrode protective layer, the negative electrode having a copper current collector and the sulfide-based solid electrolyte can be used together. Therefore, an all-solid-state battery having both the advantages of using a sulfide-based solid electrolyte and the advantages of using a copper current collector can be provided.

[0070] The above sulfide-based solid electrolyte is Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element, for example, I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m and n are integers greater than or equal to 0 and less than or equal to 12, respectively, and Z is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are integers greater than or equal to 0 and less than or equal to 12, respectively; M is one of P, Si, Ge, B, Al, Ga In), Lia 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.

[0071] 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).

[0072] As specific examples, Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8Cl 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.

[0073] The above sulfide-based solid electrolyte may be amorphous, crystalline, or a mixture thereof. For example, the above 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 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.

[0074] 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.

[0075] Of course, a commercially available solid electrolyte can be used as the sulfide-based solid electrolyte.

[0076] 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 ㎛.

[0077] 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.

[0078] When the solid electrolyte layer includes a binder, the content of the solid electrolyte may be 95 wt% to 99.5 wt%, 96 wt% to 99.5 wt%, or 97 wt% to 99 wt%, based on 100 wt% of the total solid electrolyte layer, and the content of the binder may be 0.5 wt% to 5 wt%, 0.5 wt% to 4 wt%, or 1 wt% to 3 wt%, based on 100 wt% of the total solid electrolyte layer.

[0079] The solid electrolyte layer may further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] Bipolar

[0088] 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.

[0089] The above-described positive electrode active material layer may include a positive electrode active material. The positive electrode active material may be a positive electrode active material capable of reversibly absorbing and releasing lithium ions. For example, the positive electrode active material may use at least one of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof. Specific examples of the positive electrode active material include Li a A 1-b B 1 b D 1 2(0.90≤a≤1.8, 0≤b≤0.5); Li a E 1-b B 1 b O 2-c D 1 c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5); Li a E 2-b B 1 b O 4-c D 1 c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤05); Li a Ni 1-b-c Co b B1 c D 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α≤2); Li a Ni 1-b-c Co b B 1 c O 2-α F 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Co b B 1 c O 2-α F 1 2(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mr b B 1 c D 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α≤2); Li a Ni 1-b-c Mr b B 1 c O 2-α F 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mr b B 1 c O 2-α F 1 2(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b HAVE BEEN c G d O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1); Li a Ni b Co c L 1 d G eO2(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 MnG 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); QO2; QS2; LiQS2; V2O5; LiV2O5; LiI 1 O2; LiNiVO4; Li (3-f) J2(PO4)3(0≤f≤2); Li (3-f) Fe2(PO4)3(0≤f≤2); or LiFePO4.

[0090] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; B 1 is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof; D 1 is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F 1 is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I 1 is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof; L 1 is Mn, Al or a combination thereof.

[0091] According to one implementation example, LiNi is used as the positive electrode active material. x Co y Al z O2(NCA), LiNi x Coy 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.

[0092] 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.

[0093] 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. A specific example of the buffer layer can be Li2O-ZrO2 (LZO).

[0094]

[0095] *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 under a charged state.

[0096] 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.

[0097] 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.

[0098] 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 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%.

[0099] The above positive electrode active material layer may further include a binder and / or a conductive material.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] The above 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.

[0105] 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.

[0106] The above sulfide-based 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 layer.

[0107] 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(Mg3Nb2 / 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] The above positive electrode collector may be, but is not limited to, aluminum (Al).

[0112] The thickness of the positive electrode active material layer may be 90 µm to 200 µm. For example, the thickness of the positive electrode active material layer may be 90 µm to 190 µm, 110 µm to 180 µm, or 130 µm to 150 µm.

[0113] Elastic layer

[0114] 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.

[0115] The above 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 above cushioning material may be in the form of a polymer sheet.

[0116] <Method for manufacturing cathode>

[0117] In an all-solid-state battery according to one embodiment, the negative electrode can be manufactured by the following process.

[0118] A negative electrode protective layer composition is applied to one surface of a negative electrode current collector to form a negative electrode protective layer. The negative electrode protective layer composition can be prepared by adding a fluorine-based adhesive, an acrylic adhesive, a cyanoacrylate-based adhesive, a rubber-based adhesive, a polyurethane-based adhesive, a silicone-based adhesive, or a combination thereof to a solvent. The solvent can be N-methylpyrrolidone, ethanol, hexane, water, or a combination thereof. The content of solids in the negative electrode protective layer composition can be 1 wt% to 90 wt%, 5 wt% to 70 wt%, 5 wt% to 30 wt%, or 7 wt% to 15 wt%, based on 100 wt% of the total negative electrode protective layer composition. When the content of solids is within the above range, a negative electrode protective layer sufficient to suppress a reaction between the negative electrode current collector and the solid electrolyte can be appropriately formed.

[0119] Next, a negative electrode coating layer composition is applied to one side of the negative electrode current collector facing the negative electrode protective layer, i.e., one side of the negative electrode current collector on which the negative electrode protective layer is not formed, and dried to form a negative electrode coating layer.

[0120] <Manufacturing of all-solid-state batteries>

[0121] According to one embodiment, an all-solid-state battery can be manufactured by preparing a laminate by positioning a negative electrode, a positive electrode, and a solid electrolyte layer between the negative electrode and the positive electrode, and then pressing the laminate. The pressing process can be performed at a temperature in the range of 25°C to 90°C. In addition, the pressing process can be performed by pressing at a pressure of 550 MPa or less, for example, 500 MPa or less, for example, in the range of 1 MPa to 500 MPa. The pressing time can vary depending on the temperature and pressure, and can be, for example, less than 30 minutes. The pressing process can be, for example, isostatic pressing, roll pressing, plate pressing, or warm isostatic pressing (WIP).

[0122] The above-mentioned all-solid-state secondary battery may be a unit cell having a structure of positive electrode / solid electrolyte layer / negative electrode, a bi-cell having a structure of positive electrode / solid electrolyte layer / negative electrode / solid electrolyte layer / positive electrode, or a laminated battery in which the structure of the unit cell is repeated.

[0123] 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.

[0124] 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 an anode (400) including an anode protective layer (405), an anode current collector (401) and an anode coating layer (403), a solid electrolyte layer (300), and a cathode (200) including an anode active material layer (203) and a cathode current collector (201) are laminated is housed in a case (500) such as a pouch. The all-solid-state battery (100) may further include an elastic layer on the outer side of at least one of the cathode (200) and the anode (400).

[0125] 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).

[0126] 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.

[0127] All-solid-state battery stack

[0128] An all-solid-state battery stack according to one embodiment includes a first unit cell comprising a first cathode, a first anode, and a first solid electrolyte layer positioned between the first cathode and the first anode; and a second unit cell comprising a second cathode, a second anode, and a second solid electrolyte layer positioned between the second cathode and the second anode.

[0129] Additionally, an elastic layer is included between the first cathode protective layer and the second cathode protective layer. That is, the elastic layer can be positioned between the first unit cell and the second unit cell.

[0130] FIG. 3 schematically illustrates an all-solid-state battery stack, and an all-solid-state battery stack (200) according to one embodiment includes a first unit cell (UC1) and a second unit cell (UC2), each unit cell including first and second cathodes (31, 41) including first and second cathode protective layers (311, 411), first and second cathode current collectors (312, 412) and first and second cathode coating layers (313, 413), and first and second solid electrolyte layers (12, 13). First and second cathodes (11, 21) including first and second cathode current collectors (111, 211) and first and second cathode active material layers (112, 212). Additionally, an elastic layer (61) is included between the first cathode protective layer (311) and the second cathode protective layer (411).

[0131] At this time, the elastic layer is the same as described above. In addition, the first cathode and the second cathode may be the cathodes described above, and the first anode and the second anode may be the anodes described above. The first solid electrolyte layer and the second solid electrolyte layer may be the solid electrolyte layers described above.

[0132] 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.

[0133] (Example 1)

[0134] (1) Manufacturing of cathode

[0135] A cathode protective layer composition containing 5 wt% of polyvinylidene fluoride binder was prepared by adding polyvinylidene fluoride binder to an N-methyl pyrrolidone solvent.

[0136] A mixture was prepared by mixing carbon black and silver having an average particle diameter (D50) of 60 nm in a weight ratio of 75:25, and 0.25 g of the mixture was added to 2 g of N-methyl pyrrolidone solvent containing 7 wt% of polyvinylidene fluoride binder to prepare a cathode coating layer composition.

[0137] The above cathode protective layer composition was applied to one surface of a copper foil current collector having a thickness of 10 μm and dried to produce a cathode protective layer.

[0138] The negative electrode coating layer composition was applied to the other side of the copper foil current collector facing the negative electrode protective layer, i.e., the side of the copper foil current collector opposite the negative electrode protective layer, and then vacuum-dried at 80°C to manufacture a negative electrode.

[0139] In the manufactured cathode, the thickness of the cathode protective layer was 0.1 μm, and the thickness of the cathode coating layer was 10 μm.

[0140] (2) Manufacturing of solid electrolyte layer

[0141] 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.

[0142] 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.

[0143] (3) Manufacturing of anode

[0144] Cathode active material (LiNi) 0.9 Mn 0.05Co 0.05 A mixture was prepared by mixing O2), argyrodite-type solid electrolyte Li6PS5Cl, conductive carbon nanofibers, and binder polytetrafluoroethylene in a weight ratio of 85:15:3:1.5.

[0145] The prepared mixture was coated on an aluminum foil current collector and then vacuum-dried at 45°C to prepare a positive electrode including a 160 μm thick positive electrode active material layer and a 10 μm thick current collector.

[0146] (4) Manufacturing of all-solid-state batteries

[0147] The manufactured negative electrode, solid electrolyte layer, and positive electrode were sequentially laminated, and a pressure of 500 MPa was applied to manufacture an all-solid-state battery.

[0148] (Example 2)

[0149] A negative electrode and an all-solid-state battery were manufactured in the same manner as in Example 1, except that a negative electrode protective layer having a thickness of 1 μm was manufactured.

[0150] (Example 3)

[0151] A negative electrode and an all-solid-state battery were manufactured in the same manner as in Example 1, except that a negative electrode protective layer having a thickness of 3 μm was manufactured.

[0152] (Example 4)

[0153] A negative electrode and an all-solid-state battery were manufactured in the same manner as in Example 1, except that a negative electrode protective layer having a thickness of 10 μm was manufactured.

[0154] (Example 5)

[0155] An anode and an all-solid-state battery were manufactured in the same manner as in Example 1, except that a cathode protective layer having a thickness of 0.1 μm was manufactured using a cathode protective layer composition containing 1 wt% of a polyvinylidene fluoride binder.

[0156] (Example 6)

[0157] A negative electrode and an all-solid-state battery were manufactured in the same manner as in Example 5, except that a negative electrode protective layer having a thickness of 10 μm was manufactured.

[0158] (Comparative Example 1)

[0159] (1) Manufacturing of cathode

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

[0161] The above-mentioned negative electrode coating layer slurry was applied to a copper foil current collector having a thickness of 10 μm, and then vacuum-dried at 80°C to manufacture a negative electrode. In the manufactured negative electrode, the thickness of the negative electrode coating layer was 10 μm.

[0162] (2) Manufacturing of all-solid-state batteries

[0163] An all-solid-state battery was manufactured using the above-mentioned negative electrode, the positive electrode of Example 1, and the solid electrolyte layer of Example 1 in the same manner as in Example 1.

[0164] (Comparative Example 2)

[0165] A negative electrode and an all-solid-state battery were manufactured in the same manner as in Comparative Example 1, except that a stainless steel current collector having a thickness of 10 μm was used.

[0166] (Comparative Example 3)

[0167]

[0168] *(1) Manufacturing of cathode

[0169] A cathode coating layer slurry was prepared by mixing 92 wt% of carbon black having an average particle size (D50) of 30 nm, 3 wt% of Ag having an average particle size of 60 nm, 2 wt% of carboxymethyl cellulose, and 3 wt% of styrene-butadiene rubber in water.

[0170] A conductive layer composition was prepared by mixing 10 wt% of polyvinylidene fluoride binder and 90 wt% of carbon black conductive agent in an N-methyl pyrrolidone solvent.

[0171] The conductive layer composition was applied to a copper foil current collector having a thickness of 10 μm and dried to form a conductive layer. Subsequently, the negative electrode coating layer slurry was applied to the conductive layer and vacuum-dried at 80°C to manufacture a negative electrode. In the manufactured negative electrode, the conductive layer had a thickness of 10 μm and the negative electrode coating layer had a thickness of 10 μm.

[0172] (2) Manufacturing of all-solid-state batteries

[0173] An all-solid-state battery was manufactured using the above-mentioned negative electrode, the positive electrode of Example 1, and the solid electrolyte layer of Example 1 in the same manner as in Example 1.

[0174] (Comparative Example 4)

[0175] (1) Manufacturing of cathode

[0176] The cathode protective layer composition of Example 1 was applied to one surface of a copper foil current collector having a thickness of 10 μm and dried to form a cathode protective layer.

[0177] After applying the cathode coating layer composition of Example 1 to the cathode protective layer, the cathode was vacuum-dried at 80°C to manufacture the cathode.

[0178] In the manufactured cathode, the thickness of the cathode protective layer was 10 μm, and the thickness of the cathode coating layer was 10 μm.

[0179] (2) Manufacturing of all-solid-state batteries

[0180] An all-solid-state battery was manufactured in the same manner as in Example 1 using the above-mentioned negative electrode, the above-mentioned positive electrode of Example 1, and the above-mentioned solid electrolyte layer of Example 1.

[0181]

[0182] Experimental Example 1) Photograph of the current collector after charging and discharging

[0183] The all-solid-state batteries manufactured in Examples 1 to 6 and Comparative Examples 1 to 4 were subjected to 100 charge and discharge cycles at 0.33 C at 25°C. At this time, the all-solid-state battery of Comparative Example 4 did not undergo charge and discharge, and thus subsequent experiments could not be conducted.

[0184] After charging and discharging were completed, the battery was disassembled and the negative current collector was separated. Photographs of the separated current collectors for Examples 1 to 3 and Comparative Examples 1 and 2 are shown in Fig. 4.

[0185] As shown in Fig. 4, in the cases of Examples 1 to 3, since the cathode protective layer is located between the current collector and the cathode coating layer, it can be seen that corrosion of the current collector is suppressed during charge and discharge. It can be seen that this corrosion suppression is similar to the result of the battery of Comparative Example 2 using a stainless steel current collector.

[0186] On the other hand, in the case of Comparative Example 1 where the cathode protective layer was not formed, it can be seen that excessive corrosion of the current collector occurred during charging and discharging.

[0187] Experimental Example 2) Capacity Measurement

[0188] The all-solid-state batteries manufactured in Examples 1 to 6 and Comparative Examples 1 to 3 were subjected to one 0.1 C charge and 0.1 C discharge at 25°C, followed by three 0.33 C charges and 0.33 C discharges. Subsequently, the discharge capacity was measured. The results are presented as initial capacities in Table 1 below.

[0189] Experimental Example 3) Measurement of cycle life characteristics

[0190] The all-solid-state batteries manufactured in Examples 1 to 6 and Comparative Examples 1 to 3 were subjected to 100 charge-discharge cycles at 0.33 C and 45°C, and the discharge capacity was measured. The ratio of the 100-cycle discharge capacity to the 1-cycle discharge capacity was obtained. The results are presented as capacity retention rates in Table 1 below.

[0191] Experimental Example 4) EOL (end of life) measurement

[0192] The all-solid-state batteries manufactured in Examples 1 to 6 and Comparative Examples 1 to 3 were subjected to 110 charge-discharge cycles at 0.33 C and 25 °C, and the number of cycles at which the capacity decreased by 25% was measured according to the United States Advanced Battery Consortium (USABC) regulations. The results are shown as EOL in Table 1 below.

[0193] Initial Capacity (mAh / g) Capacity Retention Rate (%) EOL Example 1 176.68 2.543 2 Example 2 179.48 3.546 3 Example 3 179.28 4.047 0 Example 4 176.08 3.846 8 Example 5 177.88 3.943 8 Example 6 175.68 3.246 5 Comparative Example 1 177.13 2.36 2 Comparative Example 2 176.58 2.947 2 Comparative Example 3 158.26 7.28 3

[0194]

[0195] As shown in Table 1 above, the all-solid-state batteries of Examples 1 to 6 exhibit high ionic conductivity, initial capacity, and excellent cycle life characteristics. In addition, the all-solid-state batteries of Examples 1 to 6 exhibited no 25% decrease in capacity even after 110 charge and discharge cycles.

[0196] On the other hand, the all-solid-state battery of Comparative Example 1 had excellent initial capacity, but exhibited very deteriorated cycle life characteristics and deteriorated EOL characteristics.

[0197] In addition, the all-solid-state battery of Comparative Example 2 exhibited low initial capacity, and the cycle life characteristics and EOL characteristics were also somewhat deteriorated.

[0198] In addition, the all-solid-state battery of Comparative Example 3 exhibited low initial capacity, cycle life characteristics, and EOL characteristics.

[0199] Experimental Example 5) Evaluation of Cyclic Voltammetry (CV) Characteristics

[0200] The cyclic current voltage (scan rate: 1 mV / s) of three electrodes using the negative electrode, lithium working electrode, and lithium counter electrode manufactured according to Examples 1 to 6 and Comparative Examples 1 to 3 was measured at 45°C using a potentiostat (Solartron, 1470E Multi-Channel Potentiostat).

[0201] The above experiment was conducted under the following conditions to determine whether a side reaction occurred. When charging and discharging under the following conditions, a normal reaction is one in which no charge-discharge reaction occurs. If charging and discharging occurs, a side reaction has occurred.

[0202] Voltage Sweep OCV (open circuit voltage) charging

[0203] 1 cycle: 4.25 V charge and 0.1 V discharge

[0204] 2nd cycle: 4.25 V charge and 0.1 V discharge

[0205] 3 times: 4.25 V charge and 0.1 V discharge

[0206] 4 times: 4.25 V charge and 0.1 V discharge

[0207] 4.25 V charge

[0208] The results of Example 1 are shown in Fig. 5, the results of Example 2 in Fig. 6, the results of Example 3 in Fig. 7, the results of Example 4 in Fig. 8, the results of Example 5 in Fig. 9, and the results of Example 6 in Fig. 10, respectively.

[0209] The results of Comparative Example 1 are shown in Fig. 11, the results of Comparative Example 2 are shown in Fig. 12, and the results of Comparative Example 3 are shown in Fig. 13.

[0210] As shown in FIGS. 5 to 10 and 12, the cathodes of Examples 1 to 6 and the cathode of Comparative Example 2 showed flat graphs, indicating that no charge / discharge reaction occurred.

[0211] On the other hand, as shown in FIG. 11 and FIG. 13, Comparative Examples 1 and 3 showed charge / discharge peaks, indicating that a side reaction occurred.

[0212] 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. A cathode comprising a cathode protective layer, a cathode coating layer, and a cathode current collector positioned between the cathode protective layer and the cathode coating layer; Bipolar; and A solid electrolyte layer positioned between the cathode and the anode All-solid-state battery.

2. In paragraph 1, The above cathode protective layer is an insulating layer in an all-solid-state battery.

3. In paragraph 1, An all-solid-state battery wherein the cathode protective layer comprises a fluorine-based adhesive, an acrylic adhesive, a cyanoacrylate-based adhesive, a rubber-based adhesive, a polyurethane-based adhesive, a silicone-based adhesive, or a combination thereof.

4. In paragraph 3, The fluorine-based adhesive is polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene, or a combination thereof, the acrylic-based adhesive is polyacrylic acid, polymethyl acrylate, polybutylacrylate, polymethyl methacrylate, poly(ethylene-co-methyl acrylate), or a combination thereof, the cyanoacrylate-based adhesive is polymethyl cyanoacrylate, polyethyl cyanoacrylate, polybutyl cyanoacrylate, polyoctyl cyanoacrylate, or a combination thereof, the rubber-based adhesive is polyisoprene, styrene-butadiene rubber, neoprene, or a combination thereof, and the polyurethane-based adhesive is 4,4'-, 2,4'-, or 2,2'-dicyclohexyl methane diisocyanate or a mixture thereof; An all-solid-state battery comprising 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane or a mixture thereof; 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate, 2,5- or 2,6-bis(isocyanatomethyl)norbornane or a mixture thereof, or a combination thereof, and the silicone-based adhesive is polymethyl siloxane, polymethylphenyl siloxane, trimethylsilyl-terminated-polymethylsiloxane, or a combination thereof.

5. In paragraph 1, An all-solid-state battery wherein the thickness of the cathode protective layer is 0.1 ㎛ to 30 ㎛.

6. In paragraph 1, An all-solid-state battery in which the negative current collector is made of copper.

7. In paragraph 1, The above solid electrolyte is an all-solid-state battery that is a sulfide-based solid electrolyte.

8. In paragraph 1, An all-solid-state battery wherein the cathode coating layer comprises a metal and a carbon-based material.

9. In paragraph 8, The above metal is an all-solid-state battery comprising Ag, Au, Sn, Zn, Al, Mg, Ge, Cu, In, Ni, Bi, Pt, Pd or a combination thereof.

10. In paragraph 8, The above carbon-based material is an all-solid-state battery, for example, crystalline carbon, amorphous carbon, or a combination thereof.

11. A first unit cell comprising a first cathode, a first anode, and a first solid electrolyte layer positioned between the first cathode and the first anode; and a second unit cell comprising a second cathode, a second anode, and a second solid electrolyte layer positioned between the second cathode and the second anode. The first cathode includes a first cathode coating layer, a first cathode current collector, and a first cathode protective layer, The second cathode includes a second cathode coating layer, a second cathode current collector, and a second cathode protective layer, An all-solid-state battery stack comprising an elastic layer positioned between the first cathode protective layer and the second cathode protective layer.

12. In paragraph 11, An all-solid-state battery stack in which the first cathode protective layer and the second cathode protective layer are insulating layers.

13. In paragraph 11, An all-solid-state battery stack, wherein the first cathode protective layer and the second cathode protective layer include a fluorine-based adhesive, an acrylic adhesive, a cyanoacrylate-based adhesive, a rubber-based adhesive, a polyurethane-based adhesive, a silicone-based adhesive, or a combination thereof.

14. In paragraph 13, The fluorine-based adhesive is polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene, or a combination thereof, the acrylic-based adhesive is polyacrylic acid, polymethyl acrylate, polybutylacrylate, polymethyl methacrylate, poly(ethylene-co-methyl acrylate), or a combination thereof, the cyanoacrylate-based adhesive is polymethyl cyanoacrylate, polyethyl cyanoacrylate, polybutyl cyanoacrylate, polyoctyl cyanoacrylate, or a combination thereof, the rubber-based adhesive is polyisoprene, styrene-butadiene rubber, neoprene, or a combination thereof, and the polyurethane-based adhesive is 4,4'-, 2,4'-, or 2,2'-dicyclohexyl methane diisocyanate or a mixture thereof; An all-solid-state battery stack comprising 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane or a mixture thereof; 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate, 2,5- or 2,6-bis(isocyanatomethyl)norbornane or a mixture thereof, and the silicone-based adhesive is polymethyl siloxane, polymethylphenyl siloxane, trimethylsilyl-terminated-polymethylsiloxane, or a combination thereof.

15. In paragraph 11, An all-solid-state battery stack wherein the thickness of the first cathode protective layer and the second cathode protective layer is 0.1 µm to 30 µm.

16. In paragraph 11, An all-solid-state battery wherein the first negative current collector and the second negative current collector are made of copper.

17. In paragraph 11, An all-solid-state battery wherein the first solid electrolyte and the second solid electrolyte are sulfide-based solid electrolytes.

18. In paragraph 11, An all-solid-state battery stack wherein the first cathode coating layer and the second cathode coating layer include a metal and a carbon-based material.

19. In paragraph 18, The above metal is an all-solid-state battery stack comprising Ag, Au, Sn, Zn, Al, Mg, Ge, Cu, In, Ni, Bi, Pt, Pd or a combination thereof.

20. In paragraph 18, The above carbon-based material is, for example, crystalline carbon, amorphous carbon, or a combination thereof, for an all-solid-state battery stack.

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