All-solid-state battery

Abstract

The present invention relates to an all-solid-state battery comprising a positive electrode, a negative electrode, and a solid electrolyte membrane interposed between the positive electrode and the negative electrode, and further comprising a first composite carbon layer and a second composite carbon layer between the negative electrode and the solid electrolyte membrane.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0056342 filed on May 9, 2022 and Korean Patent Application No. 10-2023-0046259 filed on April 7, 2023, and includes all the contents disclosed in the documents of the corresponding Korean patent applications as part of this specification.

[0002] The present invention relates to an all-solid-state battery, and more particularly, to an all-solid-state battery having improved life characteristics by including a plurality of composite carbon layers between a solid electrolyte membrane and a negative electrode.

Background Art

[0003] Lithium secondary batteries are becoming increasingly important due to the increasing use of automobiles, computers, and mobile terminals. In particular, the development of lithium secondary batteries that can obtain lightweight and high energy density is required. Such lithium secondary batteries can be manufactured by injecting a liquid electrolyte after interposing a separator between a positive electrode and a negative electrode to manufacture a lithium ion battery, or by interposing a solid electrolyte membrane between a positive electrode and a negative electrode to manufacture an all-solid-state battery.

[0004] Among these, lithium ion batteries using a liquid electrolyte have a structure in which the negative electrode and the positive electrode are partitioned by a separator. Therefore, if the separator is damaged due to deformation or external impact, a short circuit may occur, which may lead to risks such as overheating or explosion.

[0005] On the other hand, all-solid-state batteries using a solid electrolyte can increase the safety of the battery, prevent leakage of the electrolyte, and improve the reliability of the battery. However, such all-solid-state batteries have a problem that lithium dendrites are generated on the lithium metal negative electrode when charging and discharging are repeated, and a short circuit occurs in the cell.

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide an all-solid-state battery in which a composite carbon layer having different binder contents is included between a solid electrolyte membrane and a negative electrode, thereby inducing an electrical conductivity difference between both sides, and by the voltage difference generated thereby, lithium is deposited in the plane direction between the composite carbon layer and the life characteristics are improved.

Means for Solving the Problems

[0007] An embodiment of the present invention provides an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte membrane interposed between the positive electrode and the negative electrode, and further including a first composite carbon layer and a second composite carbon layer between the negative electrode and the solid electrolyte membrane.

[0008] The first composite carbon layer may be provided adjacent to one surface of the solid electrolyte membrane, and the second composite carbon layer may be provided adjacent to one surface of the negative electrode.

[0009] The first composite carbon layer and the second composite carbon layer each include a carbon material and a binder, and the binder contents of the first composite carbon layer and the second composite carbon layer may be different from each other.

[0010] The weight ratio of the carbon material and the binder in the first composite carbon layer may be 80:20 to 95:5, and the weight ratio of the carbon material and the binder in the second composite carbon layer may be 95:5 to 99:1.

[0011] The thickness ratio of the first composite carbon layer and the second composite carbon layer may be 20:1 to 1:1.

[0012] The thickness of the first composite carbon layer may be 5 to 20 μm, and the thickness of the second composite carbon layer may be 1 to 5 μm.

[0013] The solid electrolyte membrane is Li 2 S-P 2 S 5 、Li 2 S-LiI-P 2 S 5 、Li 2 S-P 2 S5 -LiCl, Li 2 S-LiI-Li 2 O-P 2 S 5 , Li 2 S-LiBr-P 2 S 5 , Li 2 S-Li 2 O-P 2 S 5 , Li 2 S-Li 3 PO 4 -P 2 S 5 , Li 2 S-P 2 S 5 -P 2 O 5 , Li 2 S-P 2 S 5 -SiS 2 , Li 2 S-P 2 S 5 -SnS, Li 2 S-P 2 S 5 -Al 2 S 3 , Li 2 S-GeS 2 , Li 2 S-GeS 2 -ZnS, Li 6 PS 5 Cl, Li 10 GeP 2 S 12 , Li 3 PS 4 , Li 7 P 3 S 11 and may include any one selected from the group consisting of these combinations.

[0014] The solid electrolyte membrane may include a sulfide-based solid electrolyte having an argyrodite structure.

[0015] The positive electrode may include a positive electrode active material and a solid electrolyte.

[0016] The carbon material may include any one selected from the group consisting of graphite, graphene, carbon black, carbon nanotubes, carbon fibers, activated carbon, and combinations thereof.

[0017] The binder may include any one selected from the group consisting of poly(vinyl acetate), polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, alkylated polyethylene oxide, crosslinked polyethylene oxide, polyvinyl ether, poly(methyl methacrylate), polyvinylidene fluoride (PVDF), a copolymer of polyhexafluoropropylene and polyvinylidene fluoride, poly(ethyl acrylate), polytetrafluoroethylene, polyvinyl chloride, polyacrylonitrile, polyvinyl pyridine, polystyrene, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), and combinations thereof.

Advantages of the Invention

[0018] According to the present invention, by including a plurality of composite carbon layers having different binder contents between the negative electrode and the solid electrolyte membrane of the all-solid-state battery, the composite carbon layer provided adjacent to the solid electrolyte membrane becomes highly elastic and acts as a protective layer in the battery, improving the physical and mechanical stability of the all-solid-state battery, preventing damage to the solid electrolyte membrane due to volume changes of the battery during charge and discharge, enhancing the interfacial stability with the negative electrode, and the composite carbon layer with a relatively low binder content induces lithium diffusion in the plane direction to prevent the precipitation of lithium dendrites, resulting in the effect of improving the life characteristics of the all-solid-state battery.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

BEST MODE FOR CARRYING OUT THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described in detail. Prior to this, terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings. The inventor is based on the principle that he can appropriately define the concept of terms in order to explain his own invention in the best way, and must be construed in a meaning and concept that conforms to the technical idea of the present invention. Therefore, the configurations described in the examples of this specification are only the most desirable embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, at the time of this application, it must be understood that there are various equivalents and modifications that can replace these.

[0021] Throughout this specification, when a part "includes" a certain component, this means that, unless otherwise stated to the contrary, it can further include other components, rather than excluding other components.

[0022] In the drawings, in order to clearly represent a plurality of layers and regions, the thickness is enlarged and shown. When a part such as a layer, film, region, or plate is "on" another part, this includes not only the case where it is "immediately on" another part, but also the case where there are other parts in between. Conversely, when a part is "immediately on" another part, it means that there are no other parts in between.

[0023] Hereinafter, a all-solid-state battery according to an embodiment will be described.

[0024] The present invention relates to an all-solid-state battery that prevents the formation of lithium dendrites and has improved physical stability and life characteristics.

[0025] Generally, all-solid-state batteries using solid electrolytes can increase the safety of the battery and prevent the leakage of electrolytes, thus improving the reliability of the battery. However, when such all-solid-state batteries are repeatedly charged and discharged, a phenomenon occurs where lithium metal is not uniformly plated on the lithium metal anode. As a result, lithium dendrites may form on the lithium metal anode, causing a short circuit in the cell, and there is a problem that the solid electrolyte membrane is damaged due to the volume change of the battery during charge and discharge.

[0026] Regarding this, in order to solve the above problems, the present invention applies a plurality of composite carbon layers with different binder contents at the anode of the all-solid-state battery, so that the composite carbon layer adjacent to the solid electrolyte membrane has high elasticity and acts as a protective layer in the battery to improve the physical and mechanical stability of the all-solid-state battery, prevent damage to the solid electrolyte membrane due to the volume change of the battery during charge and discharge, enhance the interfacial stability with the anode, and the composite carbon layer with a relatively low binder content induces lithium diffusion in the plane direction to prevent the precipitation of lithium dendrites, which has the effect of improving the life characteristics of the all-solid-state battery.

[0027] FIG. 1 is a cross-sectional view showing a schematic configuration of an all-solid-state battery according to an embodiment.

[0028] Referring to FIG. 1, an all-solid-state battery (100) according to an embodiment includes a positive electrode (50), a negative electrode (10), and a solid electrolyte membrane (40) interposed between the positive electrode and the negative electrode, and includes a second composite carbon layer (20) and a first composite carbon layer (30) between the solid electrolyte membrane and the negative electrode.

[0029] The second composite carbon layer (20) and the first composite carbon layer (30) will be described in more detail later.

[0030] The positive electrode may include a current collector and a positive electrode active material layer formed on at least one side surface of the current collector, and the positive electrode active material layer may include a positive electrode active material, a solid electrolyte, and a conductive material. Further, in a specific embodiment of the present invention, the positive electrode active material layer may further include a binder material. By adding the binder material, the adhesion between the positive electrode active material layer and the current collector and / or the solid electrolyte layer can be increased, and independently or in combination with this, it is also helpful for improving the adhesion between the components contained in the positive electrode active material.

[0031] The positive electrode active material can be used without limitation as long as it can be used as a positive electrode active material of a lithium-ion secondary battery. For example, the positive electrode active material is a layered compound such as lithium cobalt oxide (LiCoO 2 ), lithium nickel oxide (LiNiO 2 ), or a compound substituted with one or more transition metals; the chemical formula Li 1+x Mn 2-x O 4 (where x is 0 to 0.33), LiMnO 3 , LiMn 2 O 3 , LiMnO 2 and other lithium manganese oxides; lithium copper oxide (Li 2 CuO 2 ); LiV 3 O 8 , LiV 3 O 4 , V 2 O 5 , Cu 2 V 2 O 7 and other vanadium oxides; the lithium nickel oxide represented by the chemical formula LiNi 1-x M x O 2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, includes one or more of the above elements, and x = 0.01 to 0.3), for example, LiN 0.8 Co 0.1 M 0.1 O 2 ; the chemical formula LiMn 2-x M x O2 (where M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or Li 2 Mn 3 MO 8 (where M = Fe, Co, Ni, Cu or Zn) lithium manganese composite oxide; LiNi x Mn 2-x O 4 lithium manganese composite oxide with a spinel structure represented by; a part of Li in the chemical formula is substituted with alkaline earth metal ions LiMn 2 O 4 ; disulfide compound; Fe 2 (MoO 4 ) 3 etc. may be included. However, it is not limited thereto. The positive electrode active material may usually be included in the range of 70 to 95% by weight, 75 to 95% by weight or 80 to 95% by weight based on 100% by weight of the electrode layer.

[0032] The solid electrolyte contained in the positive electrode is, for example, Li 2 S-P 2 S 5 、Li 2 S-LiI-P 2 S 5 、Li 2 S-P 2 S 5 -LiCl、Li 2 S-LiI-Li 2 O-P 2 S 5 、Li 2 S-LiBr-P 2 S 5 、Li 2 S-Li 2 O-P 2 S 5 、Li 2 S-Li 3 PO 4 -P 2 S 5 、Li 2 S-P 2 S 5 -P 2 O 5 、Li 2 S-P 2 S5 -SiS 2 、 Li 2 S-P 2 S 5 -SnS, Li 2 S-P 2 S 5 -Al 2 S 3 、 Li 2 S-GeS 2 、 Li 2 S-GeS 2 -ZnS, Li 6 PS 5 Cl, Li 10 GeP 2 S 12 、 Li 3 PS 4 、 Li 7 P 3 S 11 and may include any one selected from the group consisting of these combinations, and preferably, it is a sulfide-based solid electrolyte having an argyrodite structure, Li 6 PS 5 Cl, etc. may also be included. The solid electrolyte may usually be included in the range of 1 to 30% by weight, 1 to 20% by weight, or 1 to 15% by weight based on 100% by weight of the electrode layer.

[0033] The conductive material is not particularly limited as long as it does not cause a chemical change in the battery and has conductivity. For example, graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, summer black; conductive fibers such as carbon fibers like VGCF (Vapor grown carbon fiber) and metal fibers; metal powders such as carbon fluoride, aluminum, nickel powder; conductive whiskers such as zinc oxide, potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives. The conductive material may usually be included in the range of 1 to 10% by weight or 1 to 5% by weight based on 100% by weight of the electrode layer.

[0034] The binder is not particularly limited as long as it is a component that assists in binding the active material, conductive material, etc. and binding to the current collector. For example, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, various copolymers, etc. may be mentioned. The binder may usually be contained in the range of 1 to 20% by weight, or 1 to 10% by weight based on 100% by weight of the electrode layer.

[0035] The negative electrode may include a negative electrode current collector or a negative electrode active material layer formed on the surface of the current collector.

[0036] The negative electrode current collector is not particularly limited as long as it does not cause a chemical change in the all-solid-state battery and has conductivity. For example, copper, stainless steel, nickel, titanium, fired carbon, those surface-treated with carbon, nickel, titanium, silver, etc. on the surface of copper or stainless steel may be used. Also, the negative electrode current collector may be used in various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric body, etc. having fine irregularities formed on the surface, similar to the positive electrode current collector.

[0037] In one embodiment of the present invention, the negative electrode and / or the positive electrode may further contain various additives for the purpose of complementing or improving physicochemical properties. The additives are not particularly limited, and may contain one or more additives such as oxidation stability additives, reduction stability additives, flame retardants, heat stabilizers, antifogging agents, etc.

[0038] The negative electrode and the positive electrode are each a cyclic aliphatic hydrocarbon such as cyclopentane, cyclohexane or a mixture thereof as the organic solvent during the production of the electrode slurry, an aromatic hydrocarbon such as toluene, xylene or a mixture thereof, or a solvent of the aliphatic hydrocarbon and the aromatic hydrocarbon may be used alone or in combination of two or more. The organic solvent may be appropriately selected and used depending on the drying rate and environmental conditions.

[0039] The solid electrolyte membrane (40) is provided between the negative electrode (10) and the positive electrode (50).

[0040] The solid electrolyte membrane may contain a solid electrolyte and a binder.

[0041] Examples of the solid electrolyte contained in the solid electrolyte membrane include, for example, Li 2 S-P 2 S 5 、Li 2 S-LiI-P 2 S 5 、Li 2 S-P 2 S 5 -LiCl、Li 2 S-LiI-Li 2 O-P 2 S 5 、Li 2 S-LiBr-P 2 S 5 、Li 2 S-Li 2 O-P 2 S 5 、Li 2 S-Li 3 PO 4 -P 2 S 5 、Li 2 S-P 2 S 5 -P 2 O 5 、Li 2 S-P 2 S 5 -SiS 2 、Li 2 S-P 2 S 5 -SnS、Li 2S-P 2 S 5 -Al 2 S 3 、Li 2 S-GeS 2 、Li 2 S-GeS 2 -ZnS、Li 6 PS 5 Cl、Li 10 GeP 2 S 12 、Li 3 PS 4 、Li 7 P 3 S 11 It may be any one selected from the group consisting of these and combinations thereof. The solid electrolyte may usually be contained in the range of 80 to 100% by weight, 90 to 100% by weight, or 95 to 100% by weight based on 100% by weight of the solid electrolyte membrane.

[0042] The binder contained in the solid electrolyte membrane is not particularly limited as long as it is a component that assists in binding the solid electrolyte. For example, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, various copolymers, etc. may be mentioned. The binder may usually be contained in the range of 1 to 20% by weight, or 1 to 10% by weight based on 100% by weight of the solid electrolyte membrane.

[0043] The ionic conductivity of the solid electrolyte membrane is, for example, more than 0.5×10 -3 S / cm to 1×10 -1 S / cm or less. The ionic conductivity of the solid electrolyte membrane is 0.5×10 -3If it is less than -1 S / cm, it is impossible to provide the main path for lithium ion conduction between the positive electrode and the negative electrode in the all-solid-state battery structure, and it is difficult to realize the basic cell performance. Although the higher the ionic conductivity of the solid electrolyte membrane, the more advantageous it is, when comprehensively considering the characteristics of the solid electrolyte, the limitations of performance realization, and the air stability, etc., it is desirable to limit it to the range of 1×10

[0044] In one embodiment, a second composite carbon layer (20) and a first composite carbon layer (30) are further included between the negative electrode (10) and the solid electrolyte membrane (40).

[0045] In one embodiment, the first composite carbon layer may be provided adjacent to one surface of the solid electrolyte membrane, and the second composite carbon layer may be provided adjacent to one surface of the negative electrode.

[0046] In one embodiment, the first composite carbon layer and the second composite carbon layer may include a carbon material and a binder.

[0047] The carbon material is not limited to its type as long as it can impart conductivity to the first composite carbon layer and the second composite carbon layer. For example, it may include any one selected from the group consisting of graphite, graphene, carbon black, carbon nanotubes, carbon fibers, activated carbon, and combinations thereof.

[0048] The binder may include, for example, any one selected from the group consisting of poly(vinyl acetate), polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, alkylated polyethylene oxide, crosslinked polyethylene oxide, polyvinyl ether, poly(methyl methacrylate), polyvinylidene fluoride (PVDF), a copolymer of polyhexafluoropropylene and polyvinylidene fluoride, poly(ethyl acrylate), polytetrafluoroethylene, polyvinyl chloride, polyacrylonitrile, polyvinyl pyridine, polystyrene, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), and combinations thereof, and preferably may be polyvinylidene fluoride (PVDF).

[0049] In one embodiment, the binder contents of the first composite carbon layer and the second composite carbon layer may be different from each other. Also, in one embodiment, compared with the binder content of the first composite carbon layer, the binder content of the second composite carbon layer may be more small of something.

[0050] Specifically, the weight ratio of the carbon material and the binder in the first composite carbon layer may be 80:20 to 95:5, for example, 85:15 to 95:5, or for example, 90:10.

[0051] The weight ratio of the carbon material and the binder in the second composite carbon layer may be 95:5 to 99:1, for example, 96:4 to 99:1, 97:3 to 99:1, or 98:2 to 99:1. If the carbon content in the second composite carbon layer is less than 95 parts by weight relative to the total content of carbon and binder, there are problems such as a decrease in electrical conductivity and ionic conductivity and the generation of relative overvoltage.

[0052] In the all-solid-state battery according to the present invention, the second composite carbon layer provided adjacent to one surface of the negative electrode contains a relatively higher content of carbon material than the first composite carbon layer, thereby inducing lithium diffusion in the plane direction rather than in the thickness direction of the all-solid-state battery, preventing the precipitation of lithium dendrites, and improving the life characteristics of the all-solid-state battery.

[0053] Further, the first composite carbon layer provided adjacent to one surface of the solid electrolyte membrane becomes elastically highly charged by containing a relatively higher content of binder than the second composite carbon layer, acts as a protective layer in the all-solid-state battery, can improve the physical and mechanical stability of the all-solid-state battery, prevent damage to the solid electrolyte membrane due to volume change of the battery during charge and discharge, and enhance the interfacial stability with the negative electrode.

[0054] In one embodiment, the thickness ratio of the first composite carbon layer and the second composite carbon layer may be 20:1 to 1:1, and preferably 10:1 to 2:1. Specifically, the thickness of the first composite carbon layer may be 5 μm to 20 μm, and the thickness of the second composite carbon layer may be 1 μm to 5 μm.

[0055] If the thickness of the first composite carbon layer is less than 5 μm, there is a problem that Li deposited during the battery driving process cannot be effectively separated from the electrolyte. If it exceeds 20 μm, there is a problem that a large overvoltage occurs due to the relatively increased thickness of the first composite carbon layer.

[0056] The present invention provides a battery module including the all-solid-state battery as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source.

[0057] At this time, specific examples of the device include, but are not limited to, power tools powered by an electric motor; electric vehicles including electric vehicles (EV), hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), etc.; electric two-wheel vehicles including electric bicycles (E-bike) and electric scooters (E-scooter); electric golf carts; power storage systems, etc.

[0058] Hereinafter, specific embodiments of the present invention will be presented. However, the embodiments described below are merely for specifically exemplifying or explaining the present invention, and the present invention is not limited thereby. In addition, since those skilled in the art can sufficiently technically analogize the content not described herein, the description thereof is omitted.

[0059] Example 1 1. Manufacture of slurry for forming a composite carbon layer (1) The slurry for forming the first composite carbon layer was manufactured in the following manner. Carbon black (Super P) as a carbon material and polyvinylidene fluoride (PVDF) as a binder were mixed in a ratio of 90:10 wt% in N-methylpyrrolidone (NMP) as a solvent to prepare a slurry.

[0060] (2) The slurry for forming the second composite carbon layer was manufactured in the same manner as the manufacture of the slurry for forming the first composite carbon layer, except that the content of carbon black (Super P) as a carbon material and polyvinylidene fluoride (PVDF) as a binder was mixed in a ratio of 95:5 wt%.

[0061] 2. Manufacture of the positive electrode For the preparation of the slurry, the positive electrode active material is LiCoO2 As a powder and a solid electrolyte, a crystalline sulfide solid electrolyte with an argyrodite structure, Li 6 PS 5 Cl. The conductive material is a mixture of Timcal's Super C65 and styrene-butadiene rubber (SBR) as a binder in a weight ratio of 80:15:1:4, respectively. It was put into xylene and stirred to produce a positive electrode slurry. This was applied to an aluminum current collector with a thickness of 20 μm using a doctor blade, and the resulting product was vacuum dried at 120 °C for 4 hours. Subsequently, the vacuum-dried resulting product was rolled using a cold isostatic pressing method (CIP), and a positive electrode with an electrode loading of 4 mAh / cm 2 was obtained, with an electrode layer thickness of 128 μm and a porosity of 15%.

[0062] 3. Manufacture of the solid electrolyte membrane In the solvent xylene, Li 6 PS 5 Cl powder and styrene-butadiene rubber (SBR) as a binder were mixed at 95:5 wt% to prepare a slurry. The mixed slurry was applied and coated on a release film using a doctor blade. The coating gap was 250 μm and the coating speed was 20 mm / min. The release film coated with the slurry was moved to a glass plate to maintain horizontal, dried overnight at room temperature, and vacuum dried at 100 °C for 12 hours. The thickness of the obtained solid electrolyte membrane was 100 μm.

[0063] 4. Manufacture of the battery (1) The positive electrode manufactured above was punched out into a 4 cm 2 square and prepared. As the negative electrode current collector, 6.25 cm 2A square-sized Ni foil was prepared, and a slurry for forming the second composite carbon layer manufactured above was coated on the Ni foil. The resultant was vacuum dried at 120°C for 4 hours, and a second composite carbon layer with a thickness of 5 μm was coated on one side of the negative electrode current collector.

[0064] (2) Next, a slurry for forming the first composite carbon layer manufactured above was coated on one side of a release film, and the resultant was vacuum dried at 120°C for 4 hours to prepare a size of 6.25 cm 2 square. After that, a first composite carbon layer was adhered to one side of the solid electrolyte membrane to a thickness of 10 μm using a Cold Isostatic Pressing (CIP) method.

[0065] (3) A solid electrolyte membrane was interposed between the positive electrode and the negative electrode to manufacture a half-cell. At this time, the second composite carbon layer coated on the negative electrode current collector and the first composite carbon layer coated on the solid electrolyte membrane were interposed so as to be in contact with each other, and the cells were combined in the CIP process to manufacture an all-solid-state battery.

[0066] Comparative Example 1 An all-solid-state battery was manufactured in the same manner as in Example 1, except that the first composite carbon layer and the second composite carbon layer were not formed on the negative electrode and the solid electrolyte membrane, respectively.

[0067] Comparative Example 2 An all-solid-state battery was manufactured in the same manner as in Example 1, except that the second composite carbon layer was not formed in Example 1.

[0068] Comparative Example 3 An all-solid-state battery was manufactured in the same manner as in Example 1, except that the first composite carbon layer was not formed in Example 1.

[0069] Comparative Example 4 An all-solid-state battery was manufactured in the same manner as in Example 1, except that the thickness of the first composite carbon layer was set to 3 μm in Example 1.

[0070] Comparative Example 5 In Example 1, except that a mixture of carbon black (Super P) and polyvinylidene fluoride (PVDF) at 90:10 wt% was used as the slurry for forming the second composite carbon layer, and a mixture of carbon black (Super P) and polyvinylidene fluoride (PVDF) at 95:5 wt% was used as the slurry for forming the first composite carbon layer, an all-solid-state battery was manufactured in the same manner as in Example 1.

[0071] Experimental Example 1: Evaluation of Battery Performance The energy density of the all-solid-state batteries manufactured in Example 1 and Comparative Examples 1 to 5 was evaluated based on the number of charge-discharge cycles (cycles), and the results are shown in FIG. 2.

[0072] Referring to FIG. 2, in the case of the all-solid-state battery according to Example 1, it was confirmed that the all-solid-state battery exhibited the most excellent life characteristics by showing a high capacity retention rate of about 90% or more even at about 100 charge-discharge cycles, compared to the all-solid-state batteries according to Comparative Examples 1 to 5. In particular, it was found that the capacity retention rate was as high as 96% or more at about 10 charge-discharge cycles compared to the initial stage.

[0073] In contrast, it was confirmed that the capacity retention rate of the all-solid-state battery according to Comparative Example 1, which does not have either the first composite carbon layer or the second composite carbon layer, or the all-solid-state battery according to Comparative Example 3, which does not have the first composite carbon layer, rapidly decreased compared to the initial capacity when the number of charge-discharge cycles was about 10.

[0074] Also, in the case of the all-solid-state battery according to Comparative Example 2, which does not have the second composite carbon layer, the all-solid-state battery according to Comparative Example 4, in which the thickness range of the first composite carbon layer was relatively thin, and the all-solid-state battery according to Comparative Example 5, in which the binder contents in the first composite carbon layer and the second composite carbon layer were interchanged, it was confirmed that the capacity retention rate was significantly lower than that of the all-solid-state battery according to Example 1 in all cases.

[0075] In the above, although the preferred embodiments of the present invention have been described in detail, the scope of the rights of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention defined in the following claims also belong to the scope of the rights of the present invention.

[0076] [Description of Reference Numerals] 10: Negative electrode 20: Second composite carbon layer 30: First composite carbon layer 40: Solid electrolyte membrane 50: Positive electrode 100: All-solid-state battery

Claims

1. A positive electrode; A negative electrode; and A solid electrolyte membrane interposed between the positive electrode and the negative electrode, Further including a first composite carbon layer and a second composite carbon layer between the negative electrode and the solid electrolyte membrane, The first composite carbon layer is provided adjacent to one surface of the solid electrolyte membrane, The second composite carbon layer is provided adjacent to one surface of the negative electrode, The thickness of the first composite carbon layer is 5 to 20 μm, The first composite carbon layer and the second composite carbon layer each contain a carbon material and a binder, The contents of the binders of the first composite carbon layer and the second composite carbon layer are different from each other, The weight ratio of the carbon material and the binder in the first composite carbon layer is 80:20 to 95:5, The weight ratio of the carbon material and the binder in the second composite carbon layer is 95:5 to 99:1, An all-solid-state battery.

2. The thickness ratio of the first composite carbon layer and the second composite carbon layer is 20:1 to 1:1, The all-solid-state battery according to Claim 1.

3. The thickness of the second composite carbon layer is 1 to 5 μm, The all-solid-state battery according to Claim 1.

4. The solid electrolyte membrane is Li ２ S - P ２ S ５ 、Li ２ S - LiI - P ２ S ５ 、Li ２ S - P ２ S ５ - LiCl, Li ２ S - LiI - Li ２ O - P ２ S ５ 、Li ２ S - LiBr - P ２ S ５ 、Li ２ S - Li ２ O - P ２ S ５ 、Li ２ S - Li ３ PO ４ - P ２ S ５ 、Li ２ S - P ２ S ５ - P ２ O ５ 、Li ２ S - P ２ S ５ - SiS ２ 、Li ２ S - P ２ S ５ - SnS, Li ２ S - P ２ S ５ - Al ２ S ３ 、Li ２ S - GeS ２ 、Li ２ S - GeS ２ - ZnS, Li ６ PS ５ Cl, Li １０ GeP ２ S １２ 、Li ３ PS ４ 、Li ７ P ３ S １１ and includes any one selected from the group consisting of these combinations, The all-solid-state battery according to Claim 1.

5. The solid electrolyte membrane contains a sulfide-based solid electrolyte having an argyrodite structure, The all-solid-state battery according to Claim 1.

6. The positive electrode contains a positive electrode active material and a solid electrolyte, The all-solid-state battery according to Claim 1.

7. The carbon material includes any one selected from the group consisting of graphite, graphene, carbon black, carbon nanotubes, carbon fibers, activated carbon, and combinations thereof, The all-solid-state battery according to Claim 1.

8. The binder includes any one selected from the group consisting of poly(vinyl acetate), polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, alkylated polyethylene oxide, cross-linked polyethylene oxide, polyvinyl ether, poly(methyl methacrylate), polyvinylidene fluoride (PVDF), a copolymer of polyhexafluoropropylene and polyvinylidene fluoride, poly(ethyl acrylate), polytetrafluoroethylene, polyvinyl chloride, polyacrylonitrile, polyvinyl pyridine, polystyrene, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), and combinations thereof, The all-solid-state battery according to claim 1.

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