All-solid-state battery

Abstract

The present invention relates to an all-solid-state battery, which comprises: a cathode comprising a cathode active material layer; an anode; a solid electrolyte layer disposed between the cathode and the anode and containing a solid electrolyte and a polymer matrix, wherein the thickness (b) of the solid electrolyte layer is 30-100 μm; and the polymer matrix is disposed in the solid electrolyte layer at a predetermined distance (a) from an interface in contact with the cathode, the predetermined distance (a) and the thickness (b) of the solid electrolyte layer satisfy the relationship of expression 1 below. [Expression 1] 0.05<(a / b)<0.5

Description

All-solid-state batteries

[0001] It's about all-solid-state batteries.

[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 exhibiting excellent safety and excellent ionic conductivity.

[0005] One embodiment provides an all-solid-state battery comprising: a positive electrode including a positive active material layer; a negative electrode; and a solid electrolyte layer positioned between the positive electrode and the negative electrode and including a solid electrolyte and a polymer matrix, wherein a thickness (b) of the solid electrolyte layer is 30 µm to 100 µm, the polymer matrix is ​​positioned within the solid electrolyte layer at a predetermined distance (a) from an interface in contact with the positive electrode, and the predetermined distance (a) and the thickness (b) of the solid electrolyte layer satisfy the relationship of the following equation 1.

[0006] [Formula 1]

[0007] 0.05<(a / b)<0.5

[0008] An all-solid-state battery according to one embodiment can exhibit excellent safety and ionic conductivity.

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

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

[0011] Figure 3 is a cross-sectional view schematically showing an all-solid-state battery according to another embodiment.

[0012] Figure 4 is an FE-SEM photograph of the all-solid-state battery of Example 6.

[0013] 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.

[0014] 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.

[0015] “Combination of these” means a mixture, laminate, composite, copolymer, alloy, blend, reaction product, etc. of the components.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] Throughout this specification, the description of “A and / or B” means “A or B or both.”

[0020] Unless otherwise specified herein, when a part such as a layer, film, region, plate, etc. is said to be “on” another part, this includes not only cases where it is “directly on” the other part, but also cases where there is another part in between.

[0021] 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.

[0022] "Thickness" may be measured, for example, from photographs taken with an optical microscope such as a scanning electron microscope.

[0023] One embodiment provides an all-solid-state battery comprising: a positive electrode including a positive active material layer; a negative electrode; and a solid electrolyte layer positioned between the positive electrode and the negative electrode, the solid electrolyte layer including a solid electrolyte and a polymer matrix.

[0024] In one embodiment, the polymer matrix may be positioned within the solid electrolyte layer at a predetermined distance (a) from the interface where the solid electrolyte layer contacts the positive electrode. This means that the predetermined distance (a) satisfies the relationship between the thickness (b) of the solid electrolyte layer and the following equation 1.

[0025] [Formula 1]

[0026] 0.05<(a / b)<0.5

[0027] The position of the polymer matrix is ​​described below with reference to FIG. 1. The solid electrolyte layer (300) is positioned between the positive electrode active material layer (203) of the positive electrode and the negative electrode coating layer (403) of the negative electrode, and the polymer matrix is ​​positioned within the solid electrolyte layer (300) at a certain distance (a) from the interface where the solid electrolyte layer (300) comes into contact with the positive electrode, particularly from the interface where the solid electrolyte layer (300) comes into contact with the positive electrode active material layer (203).

[0028] At this time, the constant distance (a) at which the polymer matrix is ​​positioned and the total thickness (b) of the solid electrolyte layer can satisfy the relationship of Equation 1 above, and can also satisfy the relationship of Equation 2 below.

[0029] [Formula 2]

[0030] 0.05<(a / b)<0.3

[0031] In the above formulas 1 and 2, the units of the constant distance (a) and thickness (b) may be micrometers, ㎛.

[0032] The fact that the distance (a) at which the polymer matrix is ​​located and the total thickness (b) of the solid electrolyte layer satisfy the relationship of the above equation 1 means that the polymer matrix is ​​located closer to the anode within the solid electrolyte layer.

[0033] In particular, the polymer matrix is ​​positioned within the solid electrolyte layer, within a distance of 5% to 50%, for example, 5% to 30%, of the interface in contact with the anode, with respect to 100% of the total thickness of the solid electrolyte layer. Furthermore, satisfying the relationship of Equation 1 means that the polymer matrix is ​​not positioned in contact with the anode.

[0034] Even if the polymer matrix is ​​positioned closer to the anode within the solid electrolyte layer, a short circuit may occur if a / b in Equation 1 is 0.05 or less. For example, if a / b in Equation 1 is 0.05 or less, the polymer matrix may be positioned in contact with the anode, in which case a short circuit may occur. In addition, if a / b in Equation 1 is 0.05 or less, the mechanical strength of the solid electrolyte layer is reduced, which is not suitable.

[0035] In addition, when a / b of the above formula 1 is 0.5 or more, the lithium ion migration flux moving to the negative electrode coating layer becomes non-uniform, causing lithium to be non-uniformly stacked, which may result in a deterioration in the life characteristics. In addition, when a / b of the formula 1 is 0.5 or more, the interfacial adhesion is reduced, causing lithium ions to be stacked between the solid electrolyte layer and the negative electrode interface, which may deteriorate the battery characteristics, and the polymer matrix is ​​relatively thick, which may hinder lithium ion conduction, thereby deteriorating the battery performance.

[0036] When the polymer matrix is ​​positioned within the solid electrolyte layer so as to satisfy the relationship of Equation 1, the solid electrolyte layer can exist as a free-standing membrane, and thus can be usefully applied to an all-solid-state battery.

[0037] One embodiment allows the solid electrolyte layer to exist as a self-supporting film, and thus may include a sulfide-based solid electrolyte that has superior ion conductivity compared to oxide-based electrolytes and polymer electrolytes. Since it is difficult for a sulfide-based solid electrolyte to exist as a self-supporting film, a solid electrolyte layer was formed by spraying a solid electrolyte slurry onto a positive or negative electrode to adhere it, or by impregnating a porous substrate with a sulfide-based solid electrolyte to form a solid electrolyte layer. However, this had the problem of reduced lithium ion mobility.

[0038] According to one embodiment, the solid electrolyte layer can be incorporated into an all-solid-state battery as a self-supporting membrane without these problems by including a polymer matrix inside the solid electrolyte layer, particularly at a specific location.

[0039] In one embodiment, the thickness (b) of the solid electrolyte layer may be 30 µm to 100 µm, 30 µm to 80 µm, or 40 µm to 70 µm.

[0040] When the thickness of the solid electrolyte layer is within the above range and satisfies the relationship of Equation 1, it can exhibit excellent life characteristics, ionic conductivity, and battery performance. Even if the relationship of Equation 1 is satisfied, if the thickness of the solid electrolyte layer is thinner than 30㎛, there is a high probability of short circuit due to volume change during charge and discharge, and if it is thicker than 100㎛, the path that lithium ions must move becomes longer, which may result in electrochemical deterioration.

[0041] In one embodiment, the thickness of the polymer matrix may be 5 μm to 10 μm, 6 μm to 10 μm, or 8 μm to 10 μm. When the thickness of the polymer matrix is ​​within the above range while satisfying the relationship of Equation 1, the physical properties can be improved without interfering with the path of lithium ions. For example, when the thickness of the polymer matrix satisfies the above range, it can exhibit appropriate mechanical strength, so that it can perform the role of a self-supporting membrane, and the movement path of lithium can be sufficiently maintained, so that excellent electrochemical performance can be exhibited.

[0042] In one embodiment, an example of the polymer matrix may be a nonwoven fabric.

[0043] In one embodiment, the polymer matrix may comprise polyester, polyethylene terephthalate, polypropylene, polyethylene, or a combination thereof. For example, the polymer matrix may be manufactured from such polymers. These polymers are commonly used polymers, and are primarily price-competitive. Their high flexibility allows them to sufficiently function as a free-standing electrolyte membrane.

[0044] In one embodiment, the polymer matrix may have a porosity of 50% to 99%, 60% to 95%, or 70% to 90%. When the porosity of the polymer matrix is ​​within the above range, the path of lithium ions is not obstructed, so that electrochemical performance can be well maintained. The porosity of the polymer matrix is ​​the porosity of the polymer matrix itself, and since the polymer matrix positioned within the solid electrolyte layer has the solid electrolyte impregnated within the pores, it goes without saying that the polymer matrix positioned within the solid electrolyte layer does not exist with the above porosity. In addition, since the solid electrolyte is impregnated within the pores of the polymer matrix, the relationship of the above equation 1 can be maintained even if a pressurization process is performed during the manufacturing process of the all-solid-state battery.

[0045] In the above solid electrolyte layer, the content of the polymer matrix may be 0.01 wt% to 50 wt%, 0.1 wt% to 40 wt%, or 0.2 wt% to 30 wt%, based on 100 wt% of the solid electrolyte layer. When the content of the polymer matrix is ​​within the above range, the mechanical strength of the solid electrolyte layer can be further increased, and lithium ion conductivity can be well maintained.

[0046] In the above solid electrolyte layer, the content of the solid electrolyte may be 50 wt% to 99.99 wt%, 60 wt% to 99.9 wt%, or 70 wt% to 99.8 wt%, based on 100 wt% of the solid electrolyte layer. When the content of the solid electrolyte is within the above range, better lithium ion conductivity may be exhibited.

[0047] As described above, in the solid electrolyte layer according to one embodiment, the solid electrolyte may be a sulfide-based solid electrolyte. Since the solid electrolyte is a sulfide-based solid electrolyte, it can exhibit excellent ionic conductivity and excellent lifespan characteristics over a wide operating range.

[0048] In one embodiment, the sulfide-based solid electrolyte is Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element, for example, I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m and n are integers greater than or equal to 0 and less than or equal to 12, respectively, and Z is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are integers greater than or equal to 0 and less than or equal to 12, respectively; M is one of P, Si, Ge, B, Al, Ga In), Li a M b P c S d A e (a, b, c, d and e are each integers greater than or equal to 0 and less than or equal to 12, M is Ge, Sn, Si or a combination thereof, and A is one of F, Cl, Br, or I). The sulfide-based solid electrolyte may be, for example, Li 7-x PS 6-x F x (0≤x≤2), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2) or Li 7-x PS 6-x I x (0≤x≤2) can be. Also, specifically, Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Cl, Li6PS5I, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li6.2 PS 5.2 Br 0.8 It could be the back.

[0049] 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).

[0050] As specific examples, Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 , Li6PS5I, Li 5.75 PS 4.75 Cl 1.25 , (Li 5.69 Cu 0.06 )PS 4.75 Cl 1.25 , (Li 5.72 Cu 0.03 )PS 4.75 Cl 1.25 , (Li 5.69 Cu 0.06 )P(S 4.70 (SO4) 0.05 )Cl 1.25 , (Li 5.69 Cu 0.06 )P(S 4.60 (SO4) 0.15 )Cl 1.25 , (Li 5.72 Cu 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 , (Li 5.72 Na 0.03 )P(S 4.725(SO4) 0.025 )Cl 1.25 , Li 5.75 P(S 4.725 (SO4) 0.025 )Cl 1.25 , or combinations thereof, but are not limited thereto.

[0051] The sulfide-based solid electrolyte may be amorphous, crystalline, or a mixture thereof. For example, the sulfide-based solid electrolyte may be obtained by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10, or in a molar ratio of 50:50 to 80:20. Within the above mixing ratio range, a sulfide-based solid electrolyte having excellent ionic conductivity can be produced. Here, the ionic conductivity can be further improved by further including other components such as SiS2, GeS2, and B2S3.

[0052] 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.

[0053] Of course, a commercially available solid electrolyte can be used as the sulfide-based solid electrolyte.

[0054] 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 ㎛.

[0055] 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.

[0056] The binder content in the solid electrolyte layer can be appropriately controlled and does not need to be limited.

[0057] The solid electrolyte layer may further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] [Method for manufacturing a solid electrolyte layer]

[0066] According to one embodiment, a solid electrolyte layer can be manufactured by adding a solid electrolyte to a binder solution to prepare an electrolyte mixture having an appropriate viscosity, applying the electrolyte mixture onto a polymer matrix, and drying the same. An example of the polymer matrix may be a nonwoven fabric.

[0067] To further describe the above manufacturing process, a solid electrolyte layer can be manufactured by positioning a polymer matrix on a release film, applying a mixed solution to the polymer matrix, drying, and removing the release film. The release film may include polytetrafluoroethylene, polyester, polypropylene, polyethylene, polyethylene terephthalate, or a combination thereof.

[0068] The viscosity of the electrolyte mixture may be 500 cP to 3000 cP, 600 cP to 2800 cP at room temperature (20°C to 25°C). By controlling the viscosity of the electrolyte mixture, the position of the polymer matrix within the electrolyte can be controlled. When the viscosity of the electrolyte mixture is low, the mixture can penetrate into and beneath the polymer matrix to fill the interior of the polymer matrix, and then be released beneath the polymer matrix, so that a thick solid electrolyte layer can be formed between the release film and the lower portion of the polymer matrix. In addition, when the polymer matrix is ​​sufficiently coated with the electrolyte mixture, a solid electrolyte can be formed as a layer on the upper portion of the polymer matrix as well. Accordingly, the ratio a / b, which is a certain distance (a) from the interface of the electrolyte layer in contact with the positive electrode and the thickness (b) of the solid electrolyte, can be set to 0.5.

[0069] When the viscosity of the electrolyte mixture is high, the flowability (liquid-like) of the electrolyte mixture is low, so the amount of penetration into and underneath the polymer matrix is ​​somewhat reduced, so that a thin solid electrolyte layer can be formed between the release film and the lower part of the polymer matrix, and a thick solid electrolyte layer can be formed on the upper part of the polymer matrix. Accordingly, the ratio of a / b, which is a certain distance (a) from the interface in contact with the positive electrode of the electrolyte layer and the thickness (b) of the solid electrolyte, can be set to 0.05.

[0070] For example, if the electrolyte mixture is manufactured with a viscosity of 500 cP and applied onto a polymer matrix, the low viscosity allows the electrolyte mixture to penetrate into and underneath the polymer matrix, and the ratio a / b, which is the distance (a) from the interface where the electrolyte layer contacts the anode and the thickness (b) of the solid electrolyte, can be adjusted to 0.5. In addition, if the viscosity of the electrolyte mixture is 3000 cP, the degree of penetration of the electrolyte mixture is low, so the a / b ratio can be manufactured to 0.05.

[0071] The above drying process can be carried out at 50°C to 100°C and can be carried out for 1 to 5 hours. The above drying process can be carried out by vacuum drying.

[0072] According to one embodiment, a solid electrolyte layer may be manufactured by adding a solid electrolyte to a binder solution to prepare a mixture, coating the mixture on a base film to form a first layer, positioning a polymer matrix on the first layer, and then applying the mixture to the polymer matrix to form a second layer on the polymer matrix. At this time, the total thickness of the first layer, the polymer matrix, and the second layer is the thickness of the solid electrolyte layer, and thus the thickness of the second layer may correspond to the above-described predetermined distance (a).

[0073] Regardless of the process, the solvent of the binder solution may be isobutyryl isobutyrate, xylene, toluene, benzene, hexane, or a combination thereof.

[0074] In the above binder solution, the binder is the binder described in the solid electrolyte layer.

[0075] The above-mentioned substrate film may be a release film, and may be a release polytetrafluoroethylene film, but is not limited thereto.

[0076] In the above mixed solution manufacturing process, an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer may be further added.

[0077] <Cathode>

[0078] According to one embodiment, a cathode may include a cathode current collector and a cathode coating layer positioned on the cathode current collector.

[0079] 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-containing layer, for example, a lithium deposition layer, is formed between the current collector and the negative electrode coating layer due to the deposition of lithium ions, and the lithium deposition layer functions as a negative electrode active material. Such a negative electrode is generally referred to as a deposition-type negative electrode. The carbon-based material and metal 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.

[0080] The above cathode coating layer may include a carbon-based material and a metal.

[0081] The above carbon-based material and the above metal may exist as a mixture, or the metal may exist while being supported on the carbon-based material.

[0082] The carbonaceous material may be, for example, crystalline carbon, amorphous carbon, or a combination thereof, or may be amorphous carbon. The crystalline carbon may be, for example, natural graphite, artificial graphite, mesophase carbon microbeads, carbon nanotubes, graphene, or a combination thereof. The crystalline carbon may be 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.

[0083] 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.

[0084] 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.

[0085] In one embodiment, the particle size of the primary particles may be 20 nm to 100 nm, 20 nm to 90 nm, 20 nm to 80 nm, or 30 nm to 70 nm.

[0086] In one embodiment, the particle size of the secondary particles may be 1 μm to 20 μm, 2 μm to 15 μm, or 3 μm to 10 μm.

[0087] 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.

[0088] The above metal may be Ag, Au, Sn, Zn, Al, Mg, Ge, Cu, In, Ni, Bi, Pt, Pd or a combination thereof, and may be Ag. Since the above cathode coating layer includes such a metal, it may exhibit improved electrical conductivity.

[0089] The metal may be a nanoparticle, and the size of the metal nanoparticle may be, for example, an average size of 5 nm to 800 nm, 5 nm to 700 nm, 5 nm to 500 nm, or 5 nm to 300 nm, but is not limited thereto, and any nanometer-sized particle may be appropriately used. When the metal nanoparticle having such a nanosize is used, the battery characteristics (e.g., life characteristics) of the all-solid-state battery can be improved. When the metal particle size increases to the micrometer level, the uniformity of the metal particles in the negative electrode coating layer decreases, so that the current density in a specific region increases and the cycle life characteristics may deteriorate, which is not appropriate.

[0090] In one embodiment, the content of the metal may be 14 wt% to 35 wt%, 18 wt% to 25 wt%, or 20 wt% to 24 wt% with respect to 100 wt% of the total weight of the cathode coating layer.

[0091] Additionally, the carbon-based material may be 55 wt% to 80 wt%, 60 wt% to 75 wt%, or 65 wt% to 70 wt% with respect to 100 wt% of the entire cathode coating layer.

[0092] The above cathode coating layer may include a binder. The binder may be a non-aqueous binder.

[0093] 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.

[0094] 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 12 wt%, 1 wt% to 10 wt%, 2 wt% to 8 wt%, or 2 wt% to 7 wt% relative to 100 wt% of the total cathode coating layer.

[0095] When the above binder is included in the negative electrode coating layer 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.

[0096] In one embodiment, the cathode coating layer may further include a solid electrolyte. The solid electrolyte may be an inorganic solid electrolyte such as a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a halide-based solid electrolyte, or a solid polymer electrolyte.

[0097] The above sulfide-based solid electrolyte is as described in the above solid electrolyte layer. The sulfide-based solid electrolyte included in the cathode coating layer may be the same as or different from the sulfide-based solid electrolyte included in the solid electrolyte layer.

[0098] The above oxide-based solid electrolyte is, for example, Li 1+x Ti 2-x Al(PO4)3(LTAP)(0≤x≤4), Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0≤x<1, 0≤y<1), Pb(Mg3Nb 2 / 3)O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0 <x<2, 0<y<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1, 0≤y≤1), lithium lanthanum titanate (Li x La y TiO3, 0 <x<2, 0<y<3), Li2O, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2계 세라믹스, 가넷(Garnet)계 세라믹스 Li 3+x La3M2O 12 (M= Te, Nb, or Zr, x is an integer from 1 to 10), or a mixture thereof.

[0099] 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.

[0100] 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.

[0101] The above solid polymer electrolytes include, for example, polyethylene oxide, poly(diallyldimethylammonium)trifluoromethanesulfonyl imide (poly(diallyldimethylammonium)TFSI), Cu3N, Li3N, LiPON, and Li3PO. 4· Li2S · SiS2, Li2S · GeS 2· Ga2S3, Li2O · 11Al2O3, Na2O · 11Al2O3, (Na,Li) 1+x Ti 2-x Al x (PO4)3(0.1≤x≤0.9), Li 1+x Hf 2-x Al x (PO4)3(0.1≤x≤0.9), Na3Zr2Si2PO 12 , Li3Zr2Si2PO 12 , Na5ZrP3O 12 , Na5TiP3O 12 , Na3Fe2P3O 12 , Na4NbP3O 12 , Na-Silicates, Li 0.3 La 0.5 TiO3, Na5MSi4O 12 (M is a rare earth element such as Nd, Gd, Dy) Li5ZrP3O 12 , Li5TiP3O 12 , Li3Fe2P3O 12 , Li4NbP3O 12 , Li1+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.

[0102] The above-described cathode coating layer may further include additives such as fillers, dispersants, and ionic conductive agents. In addition, known materials generally used in all-solid-state batteries may be used as fillers, dispersants, and ionic conductive agents that can be included in the cathode coating layer.

[0103] 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.

[0104] The negative current collector may be, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li) or an alloy thereof, and may be in the form of a foil or sheet. The thickness of the current collector may be 1 μm to 20 μm, 5 μm to 15 μm, or 7 μm to 10 μm.

[0105] The above-described negative 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 includes 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 can be formed, thereby further improving the cycle life of the all-solid-state battery.

[0106] 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.

[0107] According to one embodiment, the negative electrode may further include a lithium-containing layer formed during initial charging after battery manufacturing, between the current collector and the negative electrode coating layer. The thickness of the lithium-containing layer may be 1 µm to 1000 µm, 1 µm to 500 µm, 1 µm to 200 µm, 1 µm to 150 µm, 1 µm to 100 µm, or 1 µm to 50 µm. When the thickness of the lithium-containing layer is within the above range, the lithium storage function may be appropriately performed, and there may be an advantage of further improving the lifespan.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] Bipolar

[0112] 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.

[0113] 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. A specific example of the positive electrode active material is Li. a A 1-b B 1 b D 1 2(0.90≤a≤1.8, 0≤b≤0.5); Li a E 1-b B 1 b O 2-c D 1 c (0.90≤a ≤1.8, 0≤b≤0.5, 0≤c≤0.5); Li a E 2-b B 1 b O 4-c D 1 c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤05); Li a Ni 1-b-c Co b B 1 c D 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α≤2); Li a Ni 1-b-c Co b B 1 c O 2-α F 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Co b B 1 c O 2-α F 1 2(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mnb B 1 c D 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α≤2); The a Nor 1-b-c Mn b B 1 c O 2-α F 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); The a Nor 1-b-c Mn b B 1 c O 2-α F 1 2(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); The a Nor b E c G d O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1); The a Nor b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); The a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); The a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); The a MnG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); The a Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiI 1 O2; LiNiVO4; The (3-f) J2(PO4)3(0≤f≤2); The (3-f)Fe2(PO4)3(0≤f≤2); or LiFePO4.

[0114] 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.

[0115] According to one implementation example, LiNi is used as the positive electrode active material. x Co y Al z O2(NCA), LiNi x Co y Mn z O2(NCM)(but, 0 <x<1, 0<y<1, 0<z<1, x+y+z=1) 등의 삼성분계 리튬 전이 금속 산화물을 들 수 있다.

[0116] 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.

[0117] In addition, as the above coating layer, any known coating layer for the positive electrode active material of an all-solid-state battery can be applied. For example, it can be a buffer layer that plays a role in lowering the interfacial resistance between the positive electrode active material and the solid electrolyte. For example, the buffer layer can include a lithium-metal-oxide, wherein the metal can be one or more elements selected from the group consisting of Al, B, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ta, V, W, and Zr. Specific examples of the buffer layer include Li2O-ZrO2 (LZO), LiNbO2, etc.

[0118] Furthermore, when the cathode active material is a ternary compound containing nickel, cobalt, and manganese, or nickel, cobalt, and aluminum, the capacity density of the all-solid-state battery can be further improved and metal dissolution from the cathode active material can be further reduced in a charged state. Consequently, the all-solid-state battery can exhibit improved long-term reliability and cycle performance in a charged state.

[0119] 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.

[0120] 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.

[0121] 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%.

[0122] The above positive electrode active material layer may further include a binder and / or a conductive material.

[0123] 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.

[0124] 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.

[0125] The above 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 to be constructed. 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 nanotube; metal-based materials containing copper, nickel, aluminum, and silver in the form of metal powder or metal fiber; conductive polymers such as polyphenylene derivatives, or a conductive material including mixtures thereof.

[0126] 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.

[0127] 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. The solid electrolyte is as described in the above-described negative electrode coating layer, and may be the same as or different from the solid electrolyte included in the negative electrode coating layer.

[0128] 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. The above solid electrolyte may be included in an amount of 0.1 to 10 wt% to 30 wt% based on 100 wt% of the total positive electrode active material layer.

[0129] The above anode current collector may include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li) or an alloy thereof, and may be in the form of a foil or sheet.

[0130] Elastic layer

[0131] 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.

[0132] 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.

[0133] <Method for manufacturing an all-solid-state battery>

[0134] An all-solid-state battery according to one embodiment can be manufactured by a step of preparing a laminate by positioning a cathode, an anode, and a solid electrolyte layer between the cathode and the anode, and pressing the laminate.

[0135] The pressurizing process can be performed at a temperature ranging from 25°C to 90°C. In addition, the pressurizing process can be performed by pressurizing at a pressure of 550 MPa or less, for example, 500 MPa or less, for example, 1 MPa to 500 MPa. The pressurizing time can vary depending on the temperature and pressure, and can be, for example, less than 30 minutes. The pressurizing process can be, for example, isostatic pressing, roll pressing, plate pressing, or warm isostatic pressing.

[0136] 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.

[0137] 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.

[0138] FIG. 2 is a cross-sectional view of an all-solid-state battery according to an embodiment. Referring to FIG. 2, the all-solid-state battery (100) may have a structure in which an electrode assembly in which a negative electrode (400) including a negative electrode collector (401) and a negative electrode coating layer (403), a solid electrolyte layer (300), and a positive electrode (200) including a positive electrode active material layer (203) and a positive electrode collector (201) are laminated is housed in a case such as a pouch. The all-solid-state battery (100) may further include an elastic layer (500) on the outer side of at least one of the positive electrode (200) and the negative electrode (400). Although FIG. 2 illustrates one electrode assembly including the negative electrode (400), the solid electrolyte layer (300), and the positive electrode (200), an all-solid-state battery may be manufactured by laminating two or more electrode assemblies.

[0139] Fig. 3 schematically illustrates an all-solid-state battery according to another embodiment. The all-solid-state battery (100) illustrated in Fig. 3 includes a positive electrode (200) including a positive electrode current collector (201) and a positive electrode active material layer (203), a negative electrode (400) including a negative electrode current collector (401), a negative electrode coating layer (403), and a solid electrolyte (300) positioned between the positive electrode (200) and the negative electrode (400), and includes a battery case (500) in which these are housed, and further includes a lithium precipitation layer (405') between the negative electrode current collector (401) and the negative electrode coating layer (403). When the all-solid-state battery is charged, the lithium precipitation layer can be formed by lithium ions being released from the positive electrode active material and deposited on the negative electrode current collector (401').

[0140] Hereinafter, examples and comparative examples of the present invention will be described. The following examples are merely exemplary of the present invention, and the present invention is not limited to the following examples.

[0141] (Example 1)

[0142] (1) Manufacturing of solid electrolyte layer

[0143] A mixture was prepared by adding argyrodite-type solid electrolyte Li6PS5Cl to an isobutylyl isobutylate binder solution containing butyl acrylate polymer (mixing ratio of solid electrolyte and binder: 98.7:1.3 by weight, viscosity of mixture (at 25°C): 2700 cP).

[0144] After placing a polyester nonwoven fabric (porosity: 70%, thickness: 10 ㎛) on a polytetrafluoroethylene film, the above mixture having a viscosity of 2700 cP was applied to the nonwoven fabric, vacuum-dried at 80°C for 2 hours, and the polytetrafluoroethylene film was removed. Through this process, a solid electrolyte layer was manufactured in which the nonwoven fabric was positioned at a distance of 2 ㎛ from the interface where it contacts the positive electrode and had a total thickness of 30 ㎛.

[0145] (2) Manufacturing of cathode

[0146] A cathode coating layer slurry was prepared by mixing 90 wt% of Ag nanoparticles (D50: 60 nm) and 10 wt% of carbon black in a water solvent. The carbon black was a mixture of single particles with a particle diameter of 38 nm and secondary particles, and the secondary particles were assembled from primary particles with a particle diameter of 76 nm and secondary particles with a particle diameter of 275 nm.

[0147] After coating the above slurry on a stainless steel foil current collector and drying it, a negative electrode including a 12 μm thick negative electrode coating layer and a 10 μm thick current collector was manufactured.

[0148] (3) Manufacturing of anode

[0149] LiNi 0.8 Co 0.15 Mn 0.05 A cathode composition was prepared by mixing 85 wt% of O2 cathode active material, 13.5 wt% of lithium argyrodite-type solid electrolyte Li6PS5Cl, 1.0 wt% of polyvinylidene fluoride binder, and 0.5 wt% of carbon nanotube conductive material in an N-methyl pyrrolidone solvent.

[0150] The above positive electrode composition was coated on an aluminum positive electrode current collector, dried, and rolled to manufacture a positive electrode. The manufactured positive electrode included a positive electrode active material layer having a thickness of 12 μm and a current collector having a thickness of 10 μm.

[0151] (4) Manufacturing of all-solid-state full cells

[0152] The manufactured negative electrode, solid electrolyte layer, and positive electrode were sequentially laminated, and a pressure of 8 MPa was applied to manufacture an all-solid-state battery (full cell). At this time, the nonwoven fabric in the solid electrolyte layer was positioned so as to be in contact with the positive electrode active material layer in a direction at a distance (a) from the interface where it contacts the positive electrode.

[0153] (Example 2)

[0154] After placing a polyester nonwoven fabric (porosity: 80%, thickness: 10 µm) on a polytetrafluoroethylene film, a mixture having a viscosity of 800 cP (at 25°C) was applied to the nonwoven fabric, vacuum-dried at 80°C for 2 hours, and the polytetrafluoroethylene film was removed. Through this process, a solid electrolyte layer was manufactured in which the nonwoven fabric was positioned at a distance of 13.5 µm from the interface with the positive electrode and had a total thickness of 30 µm.

[0155] An all-solid-state battery was manufactured in the same manner as Example 1 except that the solid electrolyte layer was used.

[0156] (Example 3)

[0157] After placing a polyester nonwoven fabric (porosity: 90%, thickness: 10 ㎛) on a polytetrafluoroethylene film, a mixture having a viscosity of 2800 cP (at 25°C) was applied to the nonwoven fabric, vacuum-dried at 80°C for 2 hours, and the polytetrafluoroethylene film was removed. Through this process, a solid electrolyte layer was manufactured in which the nonwoven fabric was positioned at a distance of 6 ㎛ from the interface with the positive electrode and had a total thickness of 100 ㎛.

[0158] An all-solid-state battery was manufactured in the same manner as Example 1 except that the solid electrolyte layer was used.

[0159] (Example 4)

[0160] After placing a polyester nonwoven fabric (porosity: 75%, thickness: 5 μm) on a polytetrafluoroethylene film, a mixture having a viscosity of 800 cP (at 25°C) was applied to the nonwoven fabric, vacuum-dried at 80°C for 2 hours, and the polytetrafluoroethylene film was removed. Through this process, a solid electrolyte layer was manufactured in which the nonwoven fabric was positioned at a distance of 45 μm from the interface with the positive electrode and had a total thickness of 100 μm.

[0161] An all-solid-state battery was manufactured in the same manner as Example 1 except that the solid electrolyte layer was used.

[0162] (Example 5)

[0163] After placing a polyester nonwoven fabric (porosity: 78%, thickness: 8 µm) on a polytetrafluoroethylene film, a mixture having a viscosity of 600 cP (at 25°C) was applied to the nonwoven fabric, followed by vacuum drying at 80°C for 2 hours, and removal of the polytetrafluoroethylene film. Through this process, a solid electrolyte layer was manufactured in which the nonwoven fabric was positioned at a distance of 48 µm from the interface with the positive electrode and had a total thickness of 100 µm.

[0164] An all-solid-state battery was manufactured in the same manner as Example 1 except that the solid electrolyte layer was used.

[0165] (Example 6)

[0166] After placing a polyester nonwoven fabric (porosity: 78%, thickness: 10 ㎛) on a polytetrafluoroethylene film, a mixture having a viscosity of 2000 cP (at 25°C) was applied to the nonwoven fabric, vacuum-dried at 80°C for 2 hours, and the polytetrafluoroethylene film was removed. Through this process, a solid electrolyte layer was manufactured in which the nonwoven fabric was positioned at a distance of 7.5 ㎛ from the interface with the positive electrode and had a total thickness of 75 ㎛.

[0167] An all-solid-state battery was manufactured in the same manner as Example 1 except that the solid electrolyte layer was used.

[0168] (Comparative Example 1)

[0169] The mixture prepared in Example 1 was applied to a 30 μm thick polytetrafluoroethylene film and dried to form a solid electrolyte layer. The total thickness of the prepared solid electrolyte layer was 30 μm.

[0170] An all-solid-state battery was manufactured in the same manner as Example 1 except that the solid electrolyte layer was used.

[0171] (Comparative Example 2)

[0172] After placing a polyester nonwoven fabric (porosity: 78%, thickness: 10 ㎛) on a polytetrafluoroethylene film, a mixture having a viscosity of 3000 cP was applied to the nonwoven fabric, vacuum-dried at 80°C for 2 hours, and the polytetrafluoroethylene film was removed. Through this process, a solid electrolyte layer was manufactured in which the nonwoven fabric was positioned at a distance of 1.5 ㎛ from the interface where it contacts the positive electrode and had a total thickness of 30 ㎛.

[0173] An all-solid-state battery was manufactured in the same manner as Example 1 except that the solid electrolyte layer was used.

[0174] (Comparative Example 3)

[0175] After placing a polyester nonwoven fabric (porosity: 80%, thickness: 10 ㎛) on a polytetrafluoroethylene film, a mixture having a viscosity of 500 cP was applied to the nonwoven fabric, vacuum-dried at 80°C for 2 hours, and the polytetrafluoroethylene film was removed. Through this process, a solid electrolyte layer was manufactured in which the nonwoven fabric was positioned at a distance of 15 ㎛ from the interface with the positive electrode and had a total thickness of 30 ㎛.

[0176] An all-solid-state battery was manufactured in the same manner as Example 1 except that the solid electrolyte layer was used.

[0177] (Comparative Example 4)

[0178] After placing a polyester nonwoven fabric (porosity: 70%, thickness: 10 ㎛) on a heteromorphic polytetrafluoroethylene film, a mixed solution having a viscosity of 3000 cP was applied to the nonwoven fabric, vacuum-dried at 80°C for 2 hours, and the heteromorphic polytetrafluoroethylene film was removed. Through this process, a solid electrolyte layer was manufactured in which the nonwoven fabric was positioned at a distance of 5 ㎛ from the interface in contact with the positive electrode and had a total thickness of 100 ㎛.

[0179] An all-solid-state battery was manufactured in the same manner as Example 1 except that the solid electrolyte layer was used.

[0180] (Comparative Example 5)

[0181] After placing a polyester nonwoven fabric (porosity: 78%, thickness: 10 µm) on a polytetrafluoroethylene film, a mixture having a viscosity of 500 cP was applied to the nonwoven fabric, vacuum-dried at 80°C for 2 hours, and the polytetrafluoroethylene film was removed. Through this process, a solid electrolyte layer was manufactured in which the nonwoven fabric was positioned at a distance of 50 µm from the interface with the positive electrode and had a total thickness of 100 µm.

[0182] An all-solid-state battery was manufactured in the same manner as Example 1 except that the solid electrolyte layer was used.

[0183] An all-solid-state battery was manufactured in the same manner as Example 1 except that the solid electrolyte layer was used.

[0184] Experimental Example 1) Life Evaluation

[0185] The all-solid-state batteries manufactured in Examples 1 to 6 and Comparative Examples 1 to 5 were subjected to 100 charge-discharge cycles at 0.33 C. The ratio (C) of the 100-cycle discharge capacity to the 1-cycle discharge capacity was calculated according to Equation 3 below. The ratio (C) was classified according to the following criteria, and the results are shown in Table 1 below.

[0186] [Formula 3]

[0187] C = (100 discharge capacity / 1 discharge capacity) * 100

[0188] X: C<90%

[0189] O: C≥90%

[0190] Experimental Example 2) 1C discharge capacity

[0191] The all-solid-state batteries manufactured in Examples 1 to 6 and Comparative Examples 1 to 5 were charged at 0.1 C to 4.25 V and discharged at 0.1 C to 2.5 V, and then charged at 0.1 C to 4.25 V and discharged at 1 C to 2.5 V, to obtain the 1 C discharge capacity. The results are shown in Table 1 below.

[0192] In Table 1 below, since the thickness of the second layer corresponds to the distance (a) at which the nonwoven fabric is located from the interface in contact with the positive electrode active material layer, a / b is obtained from the thickness a and the thickness b of the solid electrolyte layer, and is shown in Table 1 below.

[0193] Solid electrolyte layer thickness (㎛) a / b life 1C discharge capacity (mAh / g) Example 1 300.0 67 0 168 Example 2 300.45 0 165 Example 3 1000.06 0 167 Example 4 1000.45 0 165 Example 5 300.48 0 168 Example 6 750.1 0 168 Comparative example 175 - Short circuit Short circuit Comparative example 2 300.05 Short circuit Short circuit Comparative example 3 300.5 X 121 Comparative example 4 1000.05 X 145 Comparative example 5 1000.5 X 105

[0194]

[0195] As shown in Table 1 above, in Examples 1 to 6 where a / b is greater than 0.05 and less than 0.3, excellent lifespan and high discharge capacity were exhibited. In Comparative Example 1, which did not use a non-woven fabric, a short circuit occurred, and in Comparative Example 2, where a / b is 0.05 and the solid electrolyte layer thickness is 30 μm, a short circuit occurred. In addition, in Comparative Example 3, where a / b is 0.5 and the solid electrolyte layer thickness is 30 μm, deteriorated lifespan characteristics and low discharge capacity were exhibited. In addition, in Comparative Examples 4 and 5, where the solid electrolyte layer thickness is 100 μm and a / b is 0.05 or 0.5, deteriorated lifespan characteristics were exhibited, and very low discharge capacity was exhibited.

[0196] Experimental Example 3) FE-SEM (Field Emission SEM) Evaluation

[0197] The cross-section of the all-solid-state battery manufactured in Example 6, i.e., the assembly in which the negative electrode, solid electrolyte layer, and positive electrode were laminated, was cross-polished to flatten the cross-section, and then measured using FE-SEM.

[0198] The results are shown in Fig. 4. As shown in Fig. 4, it can be seen that the 10 μm thick nonwoven fabric is located at a distance of 7.5 μm from the interface where it comes into contact with the positive electrode active material layer. That is, it can be clearly seen that a / b is 0.1.

[0199] 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 active material layer; cathode; and An all-solid-state battery comprising a solid electrolyte layer positioned between the positive electrode and the negative electrode and including a solid electrolyte and a polymer matrix, The thickness (b) of the above solid electrolyte layer is 30 ㎛ to 100 ㎛, The above polymer matrix is ​​positioned within the solid electrolyte layer at a certain distance (a) from the interface where the solid electrolyte layer comes into contact with the anode, An all-solid-state battery in which the above-mentioned constant distance (a) and the thickness (b) of the solid electrolyte layer satisfy the relationship of Equation 1 below. [Formula 1] 0.05<(a / b)<0.5 2. In paragraph 1, An all-solid-state battery in which the above-mentioned constant distance (a) and the thickness (b) of the solid electrolyte layer satisfy the relationship of Equation 2 below. [Formula 2] 0.05<(a / b)<0.3 3. In paragraph 1, An all-solid-state battery wherein the polymer matrix comprises polyester, polyethylene terephthalate, polypropylene, polyethylene or a combination thereof.

4. In paragraph 1, An all-solid-state battery wherein the thickness of the polymer matrix is ​​5 μm to 10 μm.

5. In paragraph 1, An all-solid-state battery having a porosity of the polymer matrix of 50% to 99%.

6. In paragraph 1, An all-solid-state battery wherein the content of the polymer matrix is ​​0.01 wt% to 50 wt% with respect to 100 wt% of the solid electrolyte layer.

7. In paragraph 1, An all-solid-state battery wherein the content of the solid electrolyte is 50 wt% to 99.9 wt% with respect to 100 wt% of the solid electrolyte layer.

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

9. In paragraph 8, An all-solid-state battery wherein the carbon-based material is amorphous carbon, crystalline carbon or a combination thereof.

10. In paragraph 8, The above carbon-based material is an all-solid-state battery of amorphous carbon.

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

12. In paragraph 8, An all-solid-state battery wherein the metal is Ag.

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

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