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

Abstract

The present invention relates to a negative electrode current collector; an amorphous carbon layer located on one surface of the negative electrode current collector; and a porous sheet inside the amorphous carbon layer; and relates to a negative electrode for an all-solid-state battery including the same and an all-solid-state battery including the same.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0077975 filed on Jun. 19, 2023, and includes all the contents disclosed in the literature of the Korean patent application as part of this specification.

[0002] The present invention relates to a negative electrode for an all-solid-state battery and an all-solid-state battery including the same.

Background Art

[0003] A lithium secondary battery that can be reused and has a high energy density not only can epochally reduce the use of fossil fuels but also has environmentally friendly characteristics because no by-products are generated during energy use, and thus has attracted attention as a new energy source.

[0004] The lithium secondary battery has attracted attention not only as an energy source for wearable devices or portable devices but also for devices having high output and high energy density such as electric vehicles. Therefore, research on lithium secondary batteries with high operating voltage and high energy density has been further activated.

[0005] In a lithium secondary battery, charging and discharging are performed through a process in which lithium ions move between a positive electrode and a negative electrode, and some of the lithium ions that have moved to the negative electrode adhere to the surface of the negative electrode to form lithium nuclei, and the lithium nuclei grow and can become lithium dendrites, which are dendritic crystals.

[0006] When lithium dendrites formed and grown on the surface of the negative electrode come into contact with the positive electrode, it can cause a short circuit in the lithium secondary battery, which shortens the life of the lithium secondary battery and may also cause problems in ensuring stable performance.

[0007] Furthermore, in all-solid-state batteries having a high energy density, there is a problem that short circuits frequently occur due to the weak strength of the solid electrolyte membrane disposed between the positive electrode and the negative electrode.

[0008] In order to increase the energy density of all-solid-state batteries, it has been proposed to use lithium as a negative electrode active material. The method of using lithium as a negative electrode active material includes a method of using lithium or a lithium alloy as a negative electrode active material, or a method of using lithium deposited at the interface between the negative electrode current collector and the solid electrolyte by charging without forming a negative electrode active material layer on the negative electrode current collector as an active material.

[0009] When lithium is used as the negative electrode active material, lithium is deposited on the negative electrode side during charging. When no negative electrode active material layer is formed, lithium is deposited on the negative electrode current collector. The lithium deposited on the negative electrode side in this way can grow into lithium dendrites through the gaps in the solid electrolyte when the all-solid-state battery repeatedly charges and discharges. The lithium dendrites may cause short circuits or capacity degradation of the battery. In addition, there may be a problem that the negative electrode is stressed due to the volume expansion of the negative electrode occurring during the charge and discharge process, and cracks are generated.

[0010] Therefore, there is a high demand for a technology that can prevent the growth of lithium dendrites and solve the problem of crack generation.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0012] To solve the above problems, as a result of extensive research by the present inventors, it was confirmed that when an amorphous carbon layer containing a porous sheet is formed on one surface of a negative electrode current collector, lithium dendrite can be suppressed and volume expansion of the negative electrode occurring during charge and discharge of an all-solid-state battery can be minimized, and the present invention was completed.

[0013] Accordingly, an object of the present invention is to provide a negative electrode for an all-solid-state battery that can suppress the formation of lithium dendrite, minimize volume expansion of the negative electrode, and prevent phenomena such as cracks and fractures occurring in the negative electrode.

[0014] Another object of the present invention is to provide an all-solid-state battery that can improve the life characteristics of the all-solid-state battery by including the negative electrode for an all-solid-state battery.

Means for Solving the Problems

[0015] To achieve the above object, the present invention provides a negative electrode for an all-solid-state battery including: an amorphous carbon layer located on one surface of the negative electrode current collector; and a porous sheet inside the amorphous carbon layer.

[0016] The present invention also provides an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode, wherein the negative electrode is the negative electrode for an all-solid-state battery of the present invention, and the solid electrolyte layer faces the amorphous carbon layer of the negative electrode.

Effects of the Invention

[0017] The negative electrode for an all-solid-state battery of the present invention can suppress the formation of lithium dendrite, minimize volume expansion of the negative electrode, and prevent phenomena such as cracks and fractures occurring in the negative electrode.

[0018] Accordingly, an all-solid-state battery including the same can have the effect of improving life characteristics.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0020] Hereinafter, the present invention will be described in more detail.

[0021] The terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings. Based on the principle that the inventor can appropriately define the concept of the terms in order to explain his own invention in the best way, they must be construed in a meaning and concept consistent with the technical idea of the present invention.

[0022] The terms used in the present invention are merely used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates a different meaning. In the present invention, terms such as "comprising" or "having" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should not be construed as precluding the presence or addition possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0023] Negative electrode for all-solid-state battery The present invention relates to a negative electrode for an all-solid-state battery, and the negative electrode for an all-solid-state battery of the present invention is Negative electrode current collector; An amorphous carbon layer located on one surface of the negative electrode current collector; and The inside of the amorphous carbon layer may contain a porous sheet.

[0024] The negative electrode for an all-solid-state battery of the present invention is in a form in which a negative electrode active material layer is not separately included on a negative electrode current collector. That is, the negative electrode of the present invention does not contain a negative electrode active material and may be a negative electrode in an anode free form.

[0025] FIG. 1 is a view showing a negative electrode (100) for an all-solid-state battery of the present invention. Referring to this, the negative electrode (100) for an all-solid-state battery of the present invention is in a form in which an amorphous carbon layer (120) is laminated on one surface of a negative electrode current collector (110), and a porous sheet (130) may be located inside the amorphous carbon layer (120). The porous sheet (130) may be in a form embedded in the amorphous carbon layer (120).

[0026] The negative electrode current collector (110) is not particularly limited as long as it has excellent conductivity and is electrochemically stable in the voltage range of a lithium secondary battery. For example, the negative electrode current collector (110) may be any one metal selected from the group consisting of copper, aluminum, stainless steel, titanium, silver, palladium, nickel, alloys thereof, and combinations thereof. The stainless steel may be surface-treated with carbon, nickel, titanium, or silver. As the alloy, an aluminum-cadmium alloy may be preferably used. In addition, fired carbon, a non-conductive polymer surface-treated with a conductive material, or a conductive polymer may be used.

[0027] The amorphous carbon layer (120) may be formed by dispersing amorphous carbon in a solvent to form a slurry and coating one surface of the negative electrode current collector (110) with this.

[0028] The amorphous carbon may contain carbon black such as acetylene black, furnace black, ketjen black; or graphene; etc.

[0029] The amorphous carbon layer (120) may play a role in ion transfer. More specifically, lithium ions can move from the positive electrode (200) to the negative electrode (100) or from the negative electrode (100) back to the positive electrode (200) through the amorphous carbon layer (120) without being hindered, and the lithium ions moving to the negative electrode (100) can be transmitted in the direction of the negative electrode current collector (110).

[0030] Therefore, after manufacturing a battery by laminating the negative electrode (100) for all-solid-state battery with a solid electrolyte layer (300) and a positive electrode (200) and then charging, lithium ions that have moved to the negative electrode (100) through the amorphous carbon layer (120) can be electrodeposited at the interface between the negative electrode current collector (110) and the amorphous carbon layer (120) to form a lithium layer (400), and the formation of lithium dendrites can be suppressed. Therefore, even if the negative electrode (100) for all-solid-state battery of the present invention does not contain a negative electrode active material, lithium is electrodeposited at the interface between the negative electrode current collector (110) and the amorphous carbon layer (120) through charging, so that it can function as an all-solid-state battery and suppress the formation of lithium dendrites, thus improving the life characteristics of the all-solid-state battery.

[0031] Since lithium ions move through amorphous carbon, a problem may occur in that the volume of the amorphous carbon expands during charge and discharge of the all-solid-state battery. When the volume expands, the negative electrode (100) is subjected to stress, cracks and the like occur, and the stability decreases, which may cause poor life characteristics of the all-solid-state battery.

[0032] Therefore, in the present invention, by including a support inside the amorphous carbon layer (120), the volume expansion of the amorphous carbon generated during charge and discharge of the all-solid-state battery is buffered to smooth the movement of lithium ions, and the mechanical strength is increased to improve the life characteristics of the all-solid-state battery.

[0033] That is, the present invention may include a porous sheet (130) inside the amorphous carbon layer (120), and the porous sheet (130) may serve as a support for supporting amorphous carbon.

[0034] Since the porous sheet (130) is located inside the amorphous carbon layer (120), that is, in an embedded form, it may contain amorphous carbon in the pores and on the surface of the porous sheet (130).

[0035] The porous sheet (130) may be in the form of a non-woven fabric and may be made of polyethylene, polypropylene, or a mixture thereof.

[0036] Also, the porosity of the porous sheet (130) may be 70 to 95%. Within the range of the porosity of the porous sheet (130), it can serve as a support to buffer the volume expansion of amorphous carbon generated during charge and discharge of the all-solid-state battery, and problems such as cracking or generation of cracks in the negative electrode (100) for the all-solid-state battery can be solved.

[0037] The pores of the porous sheet (130) have a structure where they are interconnected with each other, penetrate from one side of the sheet to the other side, and a fluid substance can pass through.

[0038] The volume ratio of the porous sheet (130) to the amorphous carbon layer (120) may be 5:95 to 30:70, preferably 10:90 to 20:80. Within the range of the volume ratio, the porous sheet (130) can serve as a support to buffer the volume expansion of amorphous carbon generated during charge and discharge of the all-solid-state battery. Also, amorphous carbon can smooth the movement of lithium ions, suppress the growth of lithium dendrites, and enable stable deposition of lithium at the interface between the negative electrode current collector (110) and the amorphous carbon layer (120).

[0039] The negative electrode (100) for the all-solid-state battery can be manufactured by positioning a porous sheet (130) on a negative electrode current collector (110) and then applying and drying a slurry containing amorphous carbon.

[0040] Alternatively, it can be manufactured by manufacturing a porous sheet (130) on a negative electrode current collector (110) and then applying and drying a slurry containing amorphous carbon.

[0041] In order to ensure the bonding force between the negative electrode current collector (110) and the porous sheet (130), a solution containing a binder can be cast on the negative electrode current collector (110) and then the porous sheet (130) can be positioned or manufactured. The type of the binder is not particularly limited as long as it is used in the art.

[0042] Further, since a slurry containing amorphous carbon is applied on the porous sheet (130), the porous sheet (130) may be located inside the amorphous carbon layer (120), and amorphous carbon may be located on the surface and pores of the porous sheet (130). Also, amorphous carbon may be located in a part of the pores or may be located in a form that blocks all the pores.

[0043] Preferably, a slurry containing amorphous carbon is applied and dried on the porous sheet (130) so that the porous sheet (130) is located inside the amorphous carbon layer (120). In the present invention, "inside" may mean that the porous sheet (130) is embedded in the amorphous carbon layer (120). The porous sheet (130) has a structure in which a plurality of pores are interconnected with each other and penetrate from one surface of the sheet to the other surface. Therefore, the slurry containing amorphous carbon can be inserted into the pores, or amorphous carbon can be inserted into the pores through rolling. Accordingly, all the pores can be filled with amorphous carbon, and amorphous carbon can also be located on the surface of the negative electrode current collector (110).

[0044] The amorphous carbon layer (120) can further contain a binder in order to ensure the bonding force between amorphous carbons and the bonding force between the negative electrode current collector (110) and the amorphous carbon layer (120).

[0045] The binder may include, for example, one or more selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), styrene-butylene rubber, fluorine rubber, and copolymers thereof, but is not limited thereto.

[0046] The amorphous carbon layer (120) may contain the binder in an amount of 1 to 10% by weight, preferably 3 to 7% by weight, based on the total weight of the amorphous carbon layer (120). At this time, the amorphous carbon layer (120) may mean one that does not contain a porous sheet (130) inside, that is, one composed only of amorphous carbon.

[0047] All-solid-state battery The present invention also relates to an all-solid-state battery including a positive electrode; a negative electrode; and a solid electrolyte layer positioned between the positive electrode and the negative electrode.

[0048] The negative electrode is the negative electrode for an all-solid-state battery of the present invention described above. The solid electrolyte layer may face the amorphous carbon layer of the negative electrode.

[0049] Figure 2 is a diagram showing the all-solid-state battery of the present invention. Referring to this, the all-solid-state battery of the present invention has a form in which a negative electrode (100), a solid electrolyte layer (300), and a positive electrode (200) are laminated in this order, and the amorphous carbon layer (120) of the negative electrode (100) and the solid electrolyte layer (300) may face each other.

[0050] Figure 3 shows a diagram of the all-solid-state battery of the present invention in a charged state. Referring to this, a lithium layer (400) may be formed at the interface between the negative electrode current collector (110) and the amorphous carbon layer (120). This may be because lithium ions released from the positive electrode (200) move through the solid electrolyte layer (300) and the amorphous carbon layer (120) of the negative electrode (100), and are electrodeposited at the interface between the negative electrode current collector (110) and the amorphous carbon layer (120) to form the lithium layer (400).

[0051] Therefore, in the all-solid-state battery of the present invention, a lithium layer (400) may be formed at the interface between the negative electrode current collector (110) and the amorphous carbon layer (120) upon charging. The lithium layer (400) may include all forms in which lithium metal is formed in a layer and a porous structure in which lithium metal is not formed in a layer (for example, a structure in which lithium metal aggregates in particles). In the present invention, the description will be based on the form of the lithium layer (400), but it is clear that such a description does not exclude a structure in which lithium metal is not formed in a layer.

[0052] The positive electrode (200) may include a positive electrode current collector and a positive electrode active material layer coated on one or both surfaces of the positive electrode current collector.

[0053] The positive electrode current collector may be the same as the aforementioned negative electrode current collector (110).

[0054] The positive electrode active material layer may optionally include a solid electrolyte, a conductive material, and a binder in addition to the positive electrode active material.

[0055] The positive electrode active material may be a source of lithium for forming the lithium layer (400).

[0056] The positive electrode active material may vary depending on the type of all-solid-state battery. For example, the positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; the chemical formula Li1+x Mn 2-x Lithium manganese oxides such as MnO4(0≦x≦0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7; chemical formula LiNi 1-x M x Ni-site type lithium nickel oxide represented by O2 (M = Co, Mn, Al, Cu, Fe, Mg, B or Ga; 0.01≦x≦0.3); chemical formula LiMn 2-x M x Lithium manganese composite oxide represented by O2 (M = Co, Ni, Fe, Cr, Zn or Ta; 0.01≦x≦0.1) or Li2Mn3MO8 (M = Fe, Co, Ni, Cu or Zn); LiNi x Mn 2-x Spinel structure lithium manganese composite oxide represented by MnO4; LiCoPO4; LiFePO4; elemental sulfur (Elemental sulfur, S8); Li2S n (n = 1), organic sulfur compounds or carbon-sulfur polymers ((C2S x ) n : It may contain sulfur series compounds such as x = 2.5~50, n = 2), etc., but is not limited thereto.

[0057] The conductive material is a substance that electrically connects the electrolyte and the positive electrode active material and serves as a path for electrons to move from the current collector to the positive electrode active material. As long as it does not cause a chemical change in the lithium secondary battery and has porosity and conductivity, it can be used without limitation.

[0058] For example, as the conductive material, a carbon-based material having porosity can be used. Such carbon-based materials include carbon black, graphite, graphene, activated carbon, carbon fiber, etc., metallic fibers such as metal meshes; metallic powders such as copper, silver, nickel, aluminum, etc.; or organic conductive materials such as polyphenylene derivatives. The conductive materials can be used alone or in combination.

[0059] Currently, commercially available products as conductive materials include acetylene black series (products of Chevron Chemical Company or Gulf Oil Company, etc.), Ketjen Black EC series (products of Armak Company), Vulcan XC-72 (products of Cabot Company), Super P (products of MMM), etc. For example, acetylene black, carbon black, graphite, etc. can be mentioned.

[0060] Further, the positive electrode (200) can further include a binder, and the binder enhances the adhesion force between the components constituting the positive electrode (200) and between these and the current collector, and all binders known in the art can be used.

[0061] For example, the binder may be a fluororesin-based binder including polyvinylidene fluoride (PVdF) or polytetrafluoroethylene (PTFE); a rubber-based binder including styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, styrene-isoprene rubber; a cellulose-based binder including carboxyl methyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose; a polyalcohol-based binder; a polyolefin-based binder including polyethylene, polypropylene; a polyimide-based binder; a polyester-based binder; and a silane-based binder; one kind, a mixture of two or more kinds or a copolymer selected from the group consisting thereof may be used.

[0062] The solid electrolyte may contain one or more selected from the group consisting of sulfide-based solid electrolytes, polymer-based solid electrolytes, and oxide-based solid electrolytes, and preferably may contain a sulfide-based solid electrolyte.

[0063] The sulfide-based solid electrolyte contains sulfur (S) and has ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and may include Li-P-S-based glass or Li-P-S-based glass ceramics.

[0064] Specifically, the sulfide-based solid electrolyte may contain one or more selected from the group consisting of Li6PS5Cl, Li6PS5Br, Li6PS5I, Li2S-P2S5, Li2S-LiI-P2S5, Li2S-LiI-Li2O-P2S5, Li2S-LiBr-P2S5, Li2S-Li2O-P2S5, Li2S-Li3PO4-P2S5, Li2S-P2S5-P2S5, Li2S-P2S5-SiS2, Li2S-P2S5-SnS, Li2S-P2S5-Al2S3, Li2S-GeS2, and Li2S-GeS2-ZnS, and preferably may contain one or more selected from the group consisting of Li6PS5Cl, Li6PS5Br, and Li6PS5I. The Li6PS5Cl, Li6PS5Br, and Li6PS5I may be Argyrodite type solid electrolytes. Further, the sulfide-based solid electrolyte may be in a form doped with trace elements, for example, Li6PS5Cl further doped with bromine (Br).

[0065] The polymer-based solid electrolyte is a composite of a lithium salt and a polymer resin, that is, a polymer electrolyte material in a form formed by adding a polymer resin to a solvated lithium salt, and can exhibit an ionic conductivity of about 1x10 -7 S / cm or more, preferably about 1x10 -5 S / cm or more.

[0066] Non-limiting examples of the polymer resin include polyether-based polymers, polycarbonate-based polymers, acrylate-based polymers, polysiloxane-based polymers, phosphazene-based polymers, polyethylene derivatives, alkylene oxide derivatives such as polyethylene oxide, phosphate ester polymers, polyagitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, polymers containing ionic dissociation groups, etc., and one or more of these may be included. Further, as the polymer resin of the polymer electrolyte, branched copolymers obtained by copolymerizing amorphous polymers such as PMMA, polycarbonate, polysiloxane (pdms) and / or phosphazene as comonomers on a polyethylene oxide (PEO: poly ethylene oxide) main chain, comb-like polymer resins, crosslinked polymer resins, etc. can be cited as examples, and one or more of these may be included.

[0067] In the polymer solid electrolyte, the aforementioned lithium salt is an ionizable lithium salt, and can be represented by Li + X - Although not particularly limited, examples of the anion of such a lithium salt include F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , PF6 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C -, (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - , (CF3CF2SO2)2N - etc. can be exemplified.

[0068] The oxide-based solid electrolyte may contain oxygen (O) and have ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table. For example, LLTO-based compounds, Li6La2CaTa2O 12 , Li6La2ANb2O 12 (A is Ca or Sr), Li2Nd3TeSbO 12 , Li3BO 2.5 N 0.5 , Li9SiAlO8, LAGP-based compounds, LATP-based compounds, Li 1+x Ti 2-x Al x Si y (PO4) 3-y (where 0≦x≦1, 0≦y≦1), LiAl x Zr 2-x (PO4)3 (where 0≦x≦1), LiTi x Zr 2-x (PO4)3 (where 0≦x≦1), and may contain one or more selected from LISICON-based compounds, LIPON-based compounds, perovskite-based compounds, NASICON-based compounds, and LLZO-based compounds.

[0069] The solid electrolyte layer (300) contains a solid electrolyte having lithium ion conductivity and may contain the aforementioned solid electrolyte. Further, it may further contain a binder, and the binder also follows the above.

[0070] The production of the all-solid-state battery is not particularly limited in the present invention, and known methods can be used.

[0071] As an example, after disposing a solid electrolyte membrane between a positive electrode (200) and a negative electrode (100), this is compression molded or rolled to assemble a cell. After installing the assembled cell in an exterior material, it is sealed by heating and compression or the like. As the exterior material, a laminate pack such as aluminum or stainless steel, or a metal container such as a cylindrical or rectangular shape can be used.

[0072] As an example, the positive electrode (200) is manufactured in the form of a slurry composition containing a positive electrode active material, a conductive material, a solid electrolyte, a solvent, and a binder, and is manufactured by a slurry coating process in which this is coated and then dried.

[0073] Examples of the method of coating the positive electrode slurry on a current collector include a method of distributing the positive electrode slurry on the current collector and then uniformly dispersing it using a doctor blade or the like, methods such as die casting, comma coating, and screen printing. Also, after molding on a separate substrate, the positive electrode slurry can be joined to the current collector by a pressing or lamination method. At this time, the thickness of the finally coated coating can be adjusted by adjusting the concentration of the slurry solution, the number of coating times, or the like.

[0074] The drying process is a process of removing the solvent and moisture in the slurry in order to dry the slurry coated on the metal current collector, and may vary depending on the solvent used. As an example, it is performed in a vacuum oven at 50 to 200°C. Examples of the drying method include drying by warm air, hot air, low humidity air, vacuum drying, and drying methods by irradiation with (far) infrared rays or electron beams. The drying time is not particularly limited, but is usually in the range of 30 seconds to 24 hours.

[0075] After the drying process, a cooling process can further be included, and the cooling process can be one of slow cooling to room temperature so that the recrystallized structure of the binder is successfully formed.

[0076] The shape of the all-solid-state battery is not particularly limited and can be various shapes such as cylindrical, laminated, coin-shaped, etc.

[0077] Hereinafter, preferred examples are shown to assist in the understanding of the present invention. However, the following examples are merely illustrative of the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope of the present invention and the scope of the technical idea. It is natural that such changes and modifications belong to the scope of the appended claims.

[0078] <Manufacture of All-Solid-State Battery> Example 1. A cathode active material (NCM 811), a conductive material (carbon fiber), a solid electrolyte (Li6PS5Cl), and a binder (polytetrafluoroethylene) were mixed at a weight ratio of 84:0.2:14.8:1. After the mixture was applied to and dried on a cathode current collector and then rolled, a cathode was manufactured.

[0079] A solid electrolyte (Li6PS5Cl) and a binder (styrene-butadiene-styrene copolymer) were mixed at a weight ratio of 98:2. The mixture was added to anisole to produce a slurry. After the slurry was applied and dried on a release film (polyethylene terephthalate) using a bar coater, the release film was removed to manufacture a solid electrolyte layer.

[0080] A 10-μm-thick SUS serving as the negative electrode current collector was prepared. After casting a solution containing a binder (PVDF) onto the negative electrode current collector, a porous sheet (PP / PE nonwoven fabric, porosity 89%) was placed thereon. A slurry obtained by mixing acetylene black and a binder (PVDF) at a weight ratio of 93.5:6.5 was coated and dried to produce an amorphous carbon layer. The negative electrode has an amorphous carbon layer located on the negative electrode current collector and contains a porous sheet inside the amorphous carbon layer.

[0081] While sequentially laminating the positive electrode, the solid electrolyte layer, and the negative electrode, they were laminated such that the solid electrolyte layer and the amorphous carbon layer of the negative electrode faced each other to manufacture an all-solid-state battery.

[0082] Comparative Example 1. A 10-μm-thick SUS serving as the negative electrode current collector was prepared. A slurry obtained by mixing acetylene black and a binder (PVDF) at a weight ratio of 93.5:6.5 was coated and dried to produce an amorphous carbon layer. The negative electrode has an amorphous carbon layer located on the negative electrode current collector and does not contain a porous sheet inside the amorphous carbon layer.

[0083] The positive electrode and the solid electrolyte layer were manufactured in the same manner as in Example 1 above to manufacture an all-solid-state battery.

[0084] Experimental Example 1. Measurement of the life characteristics of an all-solid-state battery The life characteristics of the all-solid-state batteries of Example 1 and Comparative Example 1 above were measured.

[0085] The measurement of the life characteristics was carried out by charging the all-solid-state battery at 60°C in CCCV mode at 0.33C until it reached 4.25V, then cutting off at 0.1C, discharging at 0.33C to 3.0V in CC mode, and measuring the capacity retention rate when 50 charge-discharge cycles were performed.

[0086] The results are shown in FIG. 4.

[0087] The all-solid-state battery of Example 1 of the present invention showed a capacity retention rate of 92.6%.

[0088] However, the all-solid-state battery of Comparative Example 1 short-circuited in the 16th cycle, showing very poor life characteristics.

[0089] That is, in the negative electrode for an all-solid-state battery, when a porous sheet is included inside the amorphous carbon layer, not only the formation of lithium dendrites is suppressed, but also the volume expansion of amorphous carbon generated when the all-solid-state battery is charged and discharged is buffered, the movement of lithium ions is smoothed, the problem of damage to the negative electrode is solved, and it can be seen that an all-solid-state battery with very excellent life characteristics can be provided.

Explanation of Reference Numerals

[0090] 100: Negative electrode 110: Negative electrode current collector 120: Amorphous carbon layer 130: Porous sheet 200: Positive electrode 300: Solid electrolyte layer 400: Lithium layer

Claims

1. A negative electrode current collector; An amorphous carbon layer located on one surface of the negative electrode current collector; and A porous sheet inside the amorphous carbon layer; A negative electrode for an all-solid-state battery, comprising:

2. The negative electrode for an all-solid-state battery according to claim 1, wherein the pores and surface of the porous sheet contain amorphous carbon.

3. The negative electrode for an all-solid-state battery according to claim 1, wherein the porous sheet is a non-woven fabric.

4. The negative electrode for an all-solid-state battery according to claim 3, wherein the non-woven fabric is made of polyethylene, polypropylene, or a mixture thereof.

5. The negative electrode for an all-solid-state battery according to claim 1, wherein the porosity of the porous sheet is 70 to 95%.

6. The negative electrode for an all-solid-state battery according to claim 1, wherein the volume ratio of the porous sheet to the amorphous carbon layer is 5:95 to 30:

70.

7. The negative electrode for an all-solid-state battery according to claim 1, wherein the amorphous carbon layer further contains a binder.

8. The negative electrode for an all-solid-state battery according to claim 7, wherein the amorphous carbon layer contains 1 to 10% by weight of a binder based on the total weight of the amorphous carbon layer.

9. The negative electrode for an all-solid-state battery according to claim 1, on which a negative electrode active material layer is not formed.

10. An all-solid-state battery comprising a positive electrode; a negative electrode; and a solid electrolyte layer located between the positive electrode and the negative electrode, wherein the negative electrode is the negative electrode for an all-solid-state battery according to any one of claims 1 to 9, and the solid electrolyte layer faces the amorphous carbon layer of the negative electrode.

11. During charging of the all-solid-state battery, Lithium electrodeposition occurs at the interface between the negative electrode current collector and the amorphous carbon layer. The all-solid-state battery according to claim 10.

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