A negative electrode for all-solid-state batteries and all-solid-state batteries containing 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 priority under Korean Patent Application No. 10-2023-0077975 dated June 19, 2023, and incorporates all the contents disclosed in the said Korean Patent Application as part of this Specification.

[0002] This invention relates to a negative electrode for an all-solid-state battery and an all-solid-state battery containing the same. [Background technology]

[0003] Reusable lithium-ion batteries, with their high energy density, are attracting attention as a new energy source that not only dramatically reduces the use of fossil fuels but also has environmentally friendly characteristics because they do not produce by-products associated with energy use.

[0004] The aforementioned lithium-ion batteries are attracting attention not only as energy sources for wearable or portable devices, but also for high-power and high-energy-density devices such as electric vehicles. Therefore, research on lithium-ion batteries with high operating voltage and energy density is becoming increasingly active.

[0005] In lithium secondary batteries, charging and discharging occur through the movement of lithium ions between the positive and negative electrodes. Some of the lithium ions that move to the negative electrode adhere to the surface of the negative electrode, forming lithium nuclei. These lithium nuclei can grow and become lithium dendrites, which are dendritic crystals.

[0006] Lithium dendrites that form and grow on the surface of the negative electrode can come into contact with the positive electrode, potentially causing a short circuit in the lithium-ion battery. This can shorten the battery's lifespan and pose a problem in ensuring stable performance.

[0007] Furthermore, in all-solid-state batteries having high energy density, there is a problem that short-circuiting frequently occurs due to the low 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, the use of lithium as a negative electrode active material has been proposed. Methods of using lithium as a negative electrode active material include a method of using lithium or a lithium alloy as the negative electrode active material, and a method of using lithium precipitated at the interface between the negative electrode current collector and the solid electrolyte by charging as the active material, in a state where a negative electrode active material layer is not formed on the negative electrode current collector.

[0009] When lithium is used as the negative electrode active material, lithium is precipitated on the negative electrode side during charging. When no negative electrode active material layer is formed, lithium is precipitated on the negative electrode current collector. When the all-solid-state battery is repeatedly charged and discharged, the lithium precipitated on the negative electrode side in this manner can grow into lithium dendrites through gaps in the solid electrolyte. The lithium dendrites may cause short-circuiting of the battery or capacity reduction. In addition, there may be a problem that cracks are generated because the negative electrode is stressed by volume expansion of the negative electrode occurring during charge and discharge processes.

[0010] Therefore, in the current situation, there is a high need for a technology that can prevent the growth of lithium dendrites and solve the problem of crack generation. [Prior Art Document] [Patent Document]

[0011] [Patent Document 1] Korean Patent Application Laid-Open No. 2018-0091678 [Brief Summary of the Invention] [Problem to be Solved by the Invention]

[0012] To solve the aforementioned problems, the inventors conducted multifaceted research and confirmed that forming an amorphous carbon layer containing a porous sheet on one surface of the negative electrode current collector suppresses lithium dendrite formation and minimizes the volume expansion of the negative electrode that occurs during charging and discharging of all-solid-state batteries, thus completing the present invention.

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

[0014] Furthermore, the present invention aims to provide an all-solid-state battery that can improve the lifespan characteristics of the all-solid-state battery by including the negative electrode for the all-solid-state battery. [Means for solving the problem]

[0015] In order to achieve the aforementioned objective, This invention is a negative electrode current collector; An amorphous carbon layer located on one surface of the negative electrode current collector; and The present invention provides a negative electrode for an all-solid-state battery, comprising a porous sheet inside the amorphous carbon layer.

[0016] Furthermore, the present invention includes a positive electrode; a negative electrode; and a solid electrolyte layer located between the positive electrode and the negative electrode. The negative electrode is the negative electrode for the all-solid-state battery of the present invention, The present invention provides an all-solid-state battery in which the solid electrolyte layer faces the amorphous carbon layer of the negative electrode. [Effects of the Invention]

[0017] The negative electrode for all-solid-state batteries of the present invention suppresses the formation of lithium dendrites, minimizes volume expansion of the negative electrode, and prevents phenomena such as cracks and fractures that occur in the negative electrode.

[0018] Therefore, all-solid-state batteries containing this technology can have the effect of improving lifespan characteristics. [Brief explanation of the drawing]

[0019] [Figure 1] This figure shows the negative electrode for the all-solid-state battery of the present invention. [Figure 2] This figure shows the all-solid-state battery of the present invention. [Figure 3] This figure shows the all-solid-state battery of the present invention in a charged state. [Figure 4] This graph shows the measured lifespan characteristics of the all-solid-state battery in Experimental Example 1. [Modes for carrying out the invention]

[0020] The present invention will be described in more detail below.

[0021] The terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner and concept consistent with the technical idea of ​​the present invention, based on the principle that inventors may appropriately define the concepts of terms in order to best describe their inventions.

[0022] The terms used in this invention are used solely to describe specific embodiments and are not intended to limit the invention. A singular expression includes plural expressions unless the context clearly indicates otherwise. In this invention, terms such as “includes” or “having” are intended to specify the existence of features, figures, stages, operations, components, parts, or combinations thereof described in the specification, and should not be understood to preemptively exclude the existence or possibility of adding one or more other features, figures, stages, operations, components, parts, or combinations thereof.

[0023] Negative electrode for all-solid-state batteries 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 amorphous carbon layer may include a porous sheet inside it.

[0024] The negative electrode for all-solid-state batteries of the present invention does not contain a separate negative electrode active material layer on the negative electrode current collector. In other words, the negative electrode of the present invention does not contain negative electrode active material and can be an anode-free negative electrode.

[0025] Figure 1 shows a negative electrode (100) for an all-solid-state battery according to the present invention. Referring to this, the negative electrode (100) for an all-solid-state battery according to the present invention has a negative electrode current collector (110) and an amorphous carbon layer (120) laminated on one surface of the 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 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 the 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. Other materials such as calcined carbon, a non-conductive polymer surface-treated with a conductive material, or a conductive polymer may also be used.

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

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

[0029] The amorphous carbon layer (120) may play a role in ion transfer. More specifically, it does not hinder lithium ions from moving from the positive electrode (200) to the negative electrode (100) or from the negative electrode (100) back to the positive electrode (200) via the amorphous carbon layer (120), and can transfer lithium ions moving to the negative electrode (100) towards the negative electrode current collector (110).

[0030] Therefore, when a battery is manufactured by laminating the negative electrode (100) for the all-solid-state battery with a solid electrolyte layer (300) and a positive electrode (200), and then charging is performed, lithium ions that have moved to the negative electrode (100) via 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), thereby suppressing the formation of lithium dendrites. Consequently, even without containing a negative electrode active material, the negative electrode (100) for the all-solid-state battery of the present invention can function as an all-solid-state battery by having lithium electrodeposited at the interface between the negative electrode current collector (110) and the amorphous carbon layer (120) through charging, thereby suppressing the formation of lithium dendrites and improving the lifespan characteristics of the all-solid-state battery.

[0031] Since lithium ions move through amorphous carbon, a problem can arise during the charging and discharging of solid-state batteries where the volume of amorphous carbon expands. When the volume expands, the negative electrode (100) is subjected to stress, which can lead to cracks and other problems, reducing stability and potentially resulting in poor lifespan characteristics for the solid-state battery.

[0032] Therefore, in the present invention, by including a support inside the amorphous carbon layer (120), the aim is to buffer the volume expansion of amorphous carbon that occurs during charging and discharging of the all-solid-state battery, thereby facilitating the movement of lithium ions, increasing mechanical strength, and improving the lifespan characteristics of the all-solid-state battery.

[0033] In other words, 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 the amorphous carbon.

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

[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] Furthermore, the porosity of the porous sheet (130) may be 70 to 95%. Within the porosity range of the porous sheet (130), it can act as a support that buffers the volume expansion of amorphous carbon generated during the charging and discharging of the all-solid-state battery, thereby solving problems such as cracking or fracture of the negative electrode (100) for the all-solid-state battery.

[0037] The pores of the porous sheet (130) are interconnected and penetrate from one side of the sheet to the other, allowing fluid substances to 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 this range of volume ratio, the porous sheet (130) can act as a support that buffers the volume expansion of amorphous carbon that occurs during charging and discharging of the all-solid-state battery. Furthermore, the amorphous carbon facilitates the movement of lithium ions, suppresses the growth of lithium dendrites, and allows lithium to be stably deposited 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 may be manufactured by placing a porous sheet (130) on a negative electrode current collector (110), and then applying and drying a slurry containing amorphous carbon.

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

[0041] 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 onto the negative electrode current collector (110), after which the porous sheet (130) can be positioned or manufactured. The type of binder is not particularly limited, as long as it is used in the industry.

[0042] Furthermore, since a slurry containing amorphous carbon is applied onto 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 in the pores of the porous sheet (130). In addition, amorphous carbon may be located in some of the pores, or it may be located in a form that completely blocks the pores.

[0043] Preferably, a slurry containing amorphous carbon may be applied to the porous sheet (130) and dried 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 and penetrate from one side of the sheet to the other, so that the slurry containing amorphous carbon can be inserted into the pores, or amorphous carbon can be inserted into the pores through rolling. Therefore, amorphous carbon can be completely filled into the penetrating pores, and amorphous carbon can also be located on the surface of the negative electrode current collector (110).

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

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

[0046] The amorphous carbon layer (120) may contain a binder in an amount of 1 to 10% by weight, preferably 3 to 7% by weight, relative to the total weight of the amorphous carbon layer (120). In this case, 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 Furthermore, the present invention relates to 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.

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

[0049] Figure 2 shows an all-solid-state battery of the present invention. Referring to this, the all-solid-state battery of the present invention has a configuration in which a negative electrode (100), a solid electrolyte layer (300), and a positive electrode (200) are stacked in that 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 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, the all-solid-state battery of the present invention may be such that a lithium layer (400) is 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 both a form in which lithium metal is formed in layers and a porous structure in which lithium metal is not formed in layers (for example, a structure in which lithium metal is aggregated in particulate form). In the present invention, the description is based on the form of the lithium layer (400), but it is clear that this description does not exclude structures in which lithium metal is not formed in layers.

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

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

[0054] The positive electrode active material layer may selectively include a positive electrode active material, a solid electrolyte, a conductive material, and a binder.

[0055] The positive electrode active material may be a lithium source for forming a 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) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; chemical formula Li1+x Mn 2-x O₄ (0 ≦ x ≦ 0.33), lithium manganese oxides such as LiMnO₃, LiMn₂O₃, LiMnO₂; lithium copper oxide (Li₂CuO₂); vanadium oxides such as LiV₃O₈, V₂O₅, Cu₂V₂O₇; lithium nickel oxide of the Ni site type represented by the chemical formula LiNi 1-x M x O₂ (M is Co, Mn, Al, Cu, Fe, Mg, B or Ga; 0.01 ≦ x ≦ 0.3); lithium manganese composite oxides represented by the chemical formula LiMn 2-x M x O₂ (M is Co, Ni, Fe, Cr, Zn or Ta; 0.01 ≦ x ≦ 0.1) or Li₂Mn₃MO₈ (M is Fe, Co, Ni, Cu or Zn); lithium manganese composite oxides having a spinel structure represented by LiNi x Mn 2-x O₄; LiCoPO₄; LiFePO₄; elemental sulfur (S₈); Li₂S n (n=1), organosulfur compounds or carbon-sulfur polymers ((C₂S x ) n : x=2.5 to 50, n=2) and other sulfur-based compounds, but may include, but are not limited to, these.

[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. Any conductive material that does not cause chemical changes in a lithium secondary battery, and has porosity and conductivity can be used without limitation.

[0058] For example, as the conductive material, a porous carbon-based material can be used. Examples of 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 may be used alone or in combination.

[0059] Currently, commercially available conductive materials include the acetylene black series (products from Chevron Chemical Company or Gulf Oil Company, etc.), the Ketjen Black EC series (products from Armak Company), Vulcan XC-72 (products from Cabot Company), and Super P (products from MMM). Examples include acetylene black, carbon black, and graphite.

[0060] Furthermore, the positive electrode (200) may further include a binder, which enhances the bonding force between the components constituting the positive electrode (200) and between them and the current collector. Any binder known in the industry can be used.

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

[0062] The solid electrolyte may include one or more selected from the group consisting of sulfide-based solid electrolytes, polymer-based solid electrolytes, and oxide-based solid electrolytes, and preferably includes 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-PS glass or Li-PS glass ceramic.

[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 contains one or more selected from the group consisting of Li6PS5Cl, Li6PS5Br, and Li6PS5I. The Li6PS5Cl, Li6PS5Br, and Li6PS5I mentioned above may be argyrodite-type solid electrolytes. Furthermore, the sulfide-based solid electrolyte may be in a form doped with trace amounts of elements; for example, Li6PS5Cl may be further doped with bromine (Br).

[0065] The aforementioned polymer solid electrolyte is a composite of a lithium salt and a polymer resin, that is, a polymer electrolyte material formed by adding a polymer resin to a solvated lithium salt, and is approximately 1 x 10⁻⁶ -7 S / cm or more, preferably about 1 x 10 -5 It can exhibit ionic conductivity of S / cm or higher.

[0066] Non-limiting examples of the polymer resin include polyether polymers, polycarbonate polymers, acrylate polymers, polysiloxane polymers, phosphazene polymers, polyethylene derivatives, alkylene oxide derivatives such as polyethylene oxide, phosphate ester polymers, agitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, polymers containing ionic dissociation groups, and may contain one or more of these. Furthermore, as the polymer electrolyte, examples of polymer resins include branched copolymers obtained by copolymerizing a polyethylene oxide (PEO) main chain with amorphous polymers such as PMMA, polycarbonate, polysiloxane (pdms) and / or phosphazene as copolymerizers, comb-like polymers, and crosslinked polymers, and may contain one or more of these.

[0067] In the polymer solid electrolyte, the lithium salt is an ionizable lithium salt, Li + X - This can be shown as follows. There are no particular limitations on the anion of such a lithium salt, but 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 - Examples include the following.

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

[0069] The solid electrolyte layer (300) contains a solid electrolyte that is lithium ion conductive, and may contain the aforementioned solid electrolyte. It may also further contain a binder, the binder also conforming to the above description.

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

[0071] As an example, a solid electrolyte membrane is placed between the positive electrode (200) and the negative electrode (100), and then the cell is assembled by compression molding or rolling. After the assembled cell is placed inside the outer packaging material, it is sealed by heating and compression or the like. As the outer packaging material, laminate packs made of aluminum, stainless steel, etc., or metal containers such as cylindrical or rectangular containers 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 slurry is coated and then dried.

[0073] Methods for coating the positive electrode slurry onto the current collector include distributing the positive electrode slurry onto the current collector and then uniformly dispersing it using a doctor blade, die casting, comma coating, and screen printing. Alternatively, the positive electrode slurry can be formed on a separate substrate and then bonded to the current collector by pressing or lamination. In this case, the thickness of the final coating can be adjusted by adjusting the concentration of the slurry solution or the number of coatings.

[0074] The drying process involves removing solvent and moisture from the slurry coated on the metal current collector in order to dry it, and may vary depending on the solvent used. For example, it is performed in a vacuum oven at 50-200°C. Drying methods include, for example, drying with hot air, hot air, low-humidity air, vacuum drying, and drying by irradiation with (far) infrared rays or electron beams. While there are no particular limitations on drying time, it is usually carried out in the range of 30 seconds to 24 hours.

[0075] The drying process may be followed by a cooling process, which may involve slow cooling to room temperature to allow for proper recrystallization of the binder.

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

[0077] The following are preferred embodiments to aid in understanding the present invention. However, these embodiments are merely illustrative of the present invention, and it will be obvious to those skilled in the art that various changes and modifications are possible within the scope of the present invention and the technical concept, and that such changes and modifications naturally fall within the scope of the attached claims.

[0078] <Manufacturing of all-solid-state batteries> Example 1. A positive electrode was manufactured by mixing a positive electrode active material (NCM 811), a conductive material (carbon fiber), a solid electrolyte (Li6PS5Cl), and a binder (polytetrafluoroethylene) in a weight ratio of 84:0.2:14.8:1, applying the mixture to a positive electrode current collector, drying it, and then rolling it.

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

[0080] A 10 μm thick stainless steel 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 on top. An amorphous carbon layer was produced by coating and drying a slurry of acetylene black and binder (PVDF) mixed in a weight ratio of 93.5:6.5. The negative electrode has an amorphous carbon layer positioned on the negative electrode current collector, with the porous sheet contained within the amorphous carbon layer.

[0081] An all-solid-state battery was manufactured by sequentially stacking the positive electrode, solid electrolyte layer, and negative electrode so that the amorphous carbon layer of the solid electrolyte layer and the negative electrode faced each other.

[0082] Comparative Example 1. A 10 μm thick stainless steel negative electrode current collector was prepared. An amorphous carbon layer was manufactured by coating the negative electrode current collector with a slurry of acetylene black and a binder (PVDF) in a weight ratio of 93.5:6.5 and then drying it. 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 solid electrolyte layer were manufactured in the same manner as in Example 1, and an all-solid-state battery was produced.

[0084] Experimental Example 1. Measurement of Life Characteristics of All-Solid-State Batteries The life characteristics of the all-solid-state batteries in Example 1 and Comparative Example 1 were measured.

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

[0086] The results are shown in Figure 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 in Comparative Example 1 experienced a short circuit in the 16th cycle, resulting in extremely poor lifespan characteristics.

[0089] In other words, by including a porous sheet inside the amorphous carbon layer in the negative electrode for an all-solid-state battery, it is possible to not only suppress the formation of lithium dendrites, but also buffer the volume expansion of amorphous carbon that occurs when the all-solid-state battery is charged and discharged, facilitate the movement of lithium ions, solve the problem of damage to the negative electrode, and provide an all-solid-state battery with excellent lifespan characteristics. [Explanation of symbols]

[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. Negative electrode current collector; An amorphous carbon layer located on one surface of the negative electrode current collector; and The amorphous carbon layer contains a porous sheet; The porous sheet is a nonwoven fabric, and is a negative electrode for an all-solid-state battery.

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

3. The negative electrode for an all-solid-state battery according to claim 1, wherein the nonwoven fabric is made of polyethylene, polypropylene, or a mixture thereof.

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

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

70.

6. The amorphous carbon layer further comprises a binder, the anode for an all-solid-state battery according to claim 1.

7. The anode for an all-solid-state battery according to claim 6, wherein the amorphous carbon layer contains a binder in an amount of 1 to 10% by weight relative to the total weight of the amorphous carbon layer.

8. The negative electrode for an all-solid-state battery according to claim 1, wherein a negative electrode active material layer is not formed on the negative electrode current collector.

9. It includes a positive electrode; a negative electrode; and a solid electrolyte layer located between the positive electrode and the negative electrode. The negative electrode is the negative electrode for an all-solid-state battery according to any one of claims 1 to 8. The solid electrolyte layer faces the amorphous carbon layer of the negative electrode, in this all-solid-state battery.

10. When charging the aforementioned all-solid-state battery, The all-solid-state battery according to claim 9, wherein lithium electrodeposition is performed at the interface between the negative electrode current collector and the amorphous carbon layer.

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