All-solid-state battery with a protective layer containing metal sulfide and method for manufacturing the same

Abstract

To provide an all-solid-state battery including a protective layer composed of a composite material including a metal sulfide and a carbon material and a manufacturing method for the same.SOLUTION: The all-solid-state battery includes an anode current collector, a protective layer located on the anode current collector, a solid electrolyte layer located on the protective layer, a cathode active material layer located on the solid electrolyte layer, and a cathode current collector located on the cathode active material layer. The protective layer may include a matrix including a composite material including a metal sulfide and a carbon material and a metal material that is dispersed in the matrix and can make an alloy with lithium.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an all-solid-state battery equipped with a protective layer made of a composite material containing a metal sulfide and a carbon material, and a method for manufacturing the same. [Background technology]

[0002] Electrochemical metal deposition is a technique for precisely coating a metal material to a desired thickness using metal ions. Most metal deposition techniques use a medium such as a liquid electrolyte, allowing metal to be produced from a liquid containing dissolved metal ions through an electrochemical reduction reaction. Typical metals that can be produced this way include Al, Mg, Ni, and Zn. When electrochemical metal deposition is applied to all-solid-state batteries, it is possible to design all-solid-state batteries without negative electrode active material. During charging of an all-solid-state battery without negative electrode, lithium ions move to the surface of the negative electrode current collector via the solid electrolyte, and these lithium ions are reduced and stored in lithium metal. At the same time, the amount of lithium deposited can be precisely controlled by adjusting the current density and charging time. As a result, the energy density per unit volume can be increased by eliminating the negative electrode active material contained in the all-solid-state battery through the electrochemical metal reduction reaction, thereby reducing the manufacturing cost of the cell.

[0003] For all-solid-state batteries without a negative electrode to be reversibly charged and discharged, lithium metal must be uniformly deposited on the surface of the negative electrode current collector inside the battery. In other words, there must be no voids between the solid electrolyte layer and the negative electrode current collector. However, due to the irregular size of the solid electrolyte layer and the hard nature of the negative electrode current collector, it is difficult to form a uniform interface.

[0004] Therefore, a functional material is needed that can fill the gap between the solid electrolyte layer and the negative electrode current collector. The functional material added to the negative electrode current collector needs to have properties such as low reversibility capacitance, electrical conductivity, and a size suitable for filling the gap. [Prior art documents] [Patent Documents]

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a all-solid-state battery provided with a protective layer capable of inducing uniform precipitation and storage of lithium ions, and a method for manufacturing the same.

[0007] The object of the present invention is not limited to the above object. The object of the present invention will become more apparent from the following description and will be realized by the means described in the claims and combinations thereof.

Means for Solving the Problems

[0008] The all-solid-state battery according to an embodiment of the present invention includes a negative electrode current collector; a protective layer located on the negative electrode current collector; a solid electrolyte layer located on the protective layer; a positive electrode active material layer located on the solid electrolyte layer; and a positive electrode current collector located on the positive electrode active material layer, and the protective layer includes a matrix made of a composite material containing a metal sulfide and a carbon material; and a metal material dispersed in the matrix and capable of alloying with lithium.

[0009] The metal sulfide is M x S y (M includes at least one selected from the group consisting of Mo, W, Cu, Co, Ti, Ni, Fe, and combinations thereof, and satisfies 1≦x≦3 and 0.5≦y≦4) and may include a compound represented by.

[0010] The carbon material may include spherical ones having a particle size (D50) of 10 nm to 100 nm; or linear ones having a cross-sectional diameter of 10 nm to 300 nm.

[0011] The carbon material may include at least one selected from the group consisting of carbon black, carbon nanotubes, carbon fibers, vapor-grown carbon fiber, and combinations thereof.

[0012] The particle size (D50) of the composite material can range from 10 nm to 1 μm.

[0013] The composite material may contain metal sulfide and carbon material in a mass ratio of 2:8 to 5:5.

[0014] The aforementioned metal material may include at least one selected from the group consisting of Ag, Zn, Mg, Bi, Sn, and combinations thereof.

[0015] The particle size (D50) of the aforementioned metal material can range from 30 nm to 500 nm.

[0016] The protective layer comprises 50% to 80% by weight of the matrix and 20% to 50% by weight of the metal material, and may have a thickness of 1 μm to 20 μm.

[0017] In the aforementioned all-solid-state battery, during charging and discharging, the metal sulfide reacts with lithium ions to convert into lithium sulfide (Li2S) and metal, and lithium is stored between the negative electrode current collector and the protective layer.

[0018] A method for manufacturing an all-solid-state battery according to one embodiment of the present invention may include the steps of: mixing a metal sulfide and a carbon material and manufacturing a composite material by mechanical milling; manufacturing a slurry containing the composite material and a metal material capable of alloying with lithium; applying the slurry onto a substrate to form a protective layer; and manufacturing a laminate containing a negative electrode current collector, a protective layer located on the negative electrode current collector, a solid electrolyte layer located on the protective layer, a positive electrode active material layer located on the solid electrolyte layer, and a positive electrode current collector located on the positive electrode active material layer. [Effects of the Invention]

[0019] According to the present invention, an all-solid-state battery can be obtained in which lithium metal can be uniformly deposited and stored on the negative electrode current collector.

[0020] According to the present invention, an all-solid-state battery with significantly improved energy density can be obtained.

[0021] The effects of the present invention are not limited to those described above. The effects of the present invention should be understood to include all effects that can be inferred from the following description. [Brief explanation of the drawing]

[0022] [Figure 1] This figure shows the all-solid-state battery according to the present invention. [Figure 2] This figure shows the all-solid-state battery according to the present invention in a charged state. [Figure 3] These are the results of scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) analysis of the composite material of Example 1. [Figure 4] This shows the scanning electron microscope-X-ray spectroscopy (SEM-EDS) results for the protective layer of Example 1. [Figure 5] This is the result of analyzing a cross-section of a half-cell after initial deposition of the protective layer according to Example 1 using a scanning electron microscope (SEM). [Figure 6] This shows the initial charge and discharge results of a half-cell with the protective layer introduced according to Example 1. [Figure 7] This shows the initial charge and discharge results of a half-cell with a protective layer introduced, as in the comparative example. [Figure 8] This is a charge-discharge cycle graph of a half-cell with a protective layer introduced according to Example 1. [Figure 9a] This is a charge-discharge cycle graph of a half-cell with a protective layer introduced according to Example 2. [Figure 9b] This is an initial charge-discharge graph of a half-cell with a protective layer introduced according to Example 2. [Figure 10]This is a charge-discharge cycle graph of a half-cell with a protective layer introduced according to Example 3. [Figure 11] This is a charge-discharge cycle graph of a half-cell with a protective layer introduced according to Example 4. [Modes for carrying out the invention]

[0023] The above-described objects, other objects, features, and advantages of the present invention will be readily apparent from the following preferred embodiments relating to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. The embodiments presented herein are provided to ensure that the disclosure is thorough and complete and that the idea of ​​the present invention is fully conveyed to a person of the ordinary skill.

[0024] Terms such as “includes” or “having” as used herein are intended to specify the presence of features, figures, stages, operations, components, parts, or combinations thereof as described in the specification, and should be understood not to preemptively exclude the presence or possibility of adding one or more other features, figures, stages, operations, components, parts, or combinations thereof. Furthermore, when a part such as a layer, film, region, or plate is said to be “on top” of another part, this includes not only when it is “directly on top” of the other part, but also when there is another part between them. Conversely, when a part such as a layer, film, region, or plate is said to be “below” another part, this includes not only when it is “directly below” the other part, but also when there is another part between them.

[0025] Unless otherwise explicitly stated, all numbers, values, and / or expressions used herein to express quantities of components, reaction conditions, polymer compositions, and formulations should be understood to be modified in all cases by the term "approximately," as these are approximations that reflect the various uncertainties of measurement that arise in obtaining such values ​​from among essentially different numbers. Furthermore, where numerical ranges are disclosed herein, such ranges are continuous and, unless otherwise noted, include all values ​​from the minimum to the maximum value of such range. And, where such ranges refer to integers, unless otherwise noted, include all integers from the minimum to the maximum value of such range.

[0026] Figure 1 shows an all-solid-state battery according to the present invention. Referring to this, the all-solid-state battery may consist of a negative electrode current collector 10, a protective layer 20, an all-solid electrolyte layer 30, a positive electrode active material layer 40, and a positive electrode current collector 50, all stacked together.

[0027] Figure 2 shows the all-solid-state battery according to the present invention in a charged state. Referring to this,

[0028] The all-solid-state battery may include a lithium metal layer 60 between the negative electrode current collector 10 and the protective layer 20.

[0029] The negative electrode current collector 10 may be a plate-shaped substrate having electrical conductivity. Specifically, the negative electrode current collector 10 may be in the form of a sheet, a thin film, or a foil.

[0030] The negative electrode current collector 10 may include a material that does not react with lithium. Specifically, the negative electrode current collector 10 may include at least one selected from the group consisting of Ni, Cu, SUS (stainless steel), and combinations thereof.

[0031] The protective layer 20 is configured to guide lithium ions flowing in from the positive electrode active material layer 40 and uniformly deposit and store them on the negative electrode current collector 10.

[0032] The protective layer 20 may include a matrix made of a composite material containing a metal sulfide and a carbon material, and a metal material dispersed in the matrix.

[0033] The composite material may not be a simple mixture of the metal sulfide and the carbon material, but rather a composite material formed by mechanical milling of the metal sulfide and the carbon material. Mechanical milling reduces the particle size of the metal sulfide to nanoscale. The particle size (D50) of the composite material is determined by the particle size (D50) of the starting material, the carbon material. This will be described later. After mixing the metal sulfide and the carbon material, the metal sulfide is crushed along the surface of the carbon material by mechanical milling to obtain a composite material in which the metal sulfide is dispersed very uniformly on the surface of the carbon material.

[0034] During the charging and discharging of the all-solid-state battery, the metal sulfide can react with lithium ions to be converted into lithium sulfide (Li2S) and metal. The charging and discharging may be a chemical conversion process. As a result, during the charging and discharging of the all-solid-state battery, the composite material can exist in the form of lithium sulfide (Li2S), metal, and carbon material. Within the protective layer 20, the lithium sulfide (Li 2S The metal and the carbon material are involved in the movement of lithium ions, and the carbon material serves as a pathway for electron movement.

[0035] The metal sulfide may include a metal sulfide that does not react with lithium ions to form an alloy. Specifically, the metal sulfide is M x S y The compound may be represented as (where M includes at least one selected from the group consisting of Mo, W, Cu, Co, Ti, Ni, Fe and combinations thereof, satisfying 1 ≤ x ≤ 3 and 0.5 ≤ y ≤ 4). Preferably, the metal sulfide may include MoS2.

[0036] The carbon material may include at least one selected from the group consisting of carbon black, carbon nanotubes, carbon fibers, vapor-grown carbon fibers, and combinations thereof.

[0037] The particle size (D50) of the composite material can be 10 nm to 1 μm. When the particle size (D50) of the composite material falls within the above numerical range, the composite material can fill the gap between the solid electrolyte layer 30 and the negative electrode current collector 10, thereby forming a good interface.

[0038] The composite material may contain metal sulfide and carbon material in a mass ratio of 2:8 to 5:5. When the mass ratio of metal sulfide to carbon material falls within the above numerical range, the lithium ion and electron transport pathways within the protective layer 20 can be formed in a well-balanced manner. In particular, if the content of metal sulfide is excessive, initial irreversibility increases, which may reduce the battery capacity and decrease the electrical conductivity of the protective layer 20.

[0039] The aforementioned metallic material is a metal capable of forming an alloy with lithium, and may include at least one selected from the group consisting of Ag, Zn, Mg, Bi, Sn, and combinations thereof.

[0040] The particle size (D50) of the metal material may be between 30 nm and 500 nm. When the particle size (D50) of the metal material falls within the above numerical range, the reaction with lithium ions is uniform and easy. In particular, if the particle size (D50) of the metal material exceeds 500 nm, it may not be suitable as a metal seed.

[0041] The protective layer 20 may contain 50% to 80% by weight of the matrix and 20% to 50% by weight of the metal material. If the content of the metal material exceeds 50% by weight, the lithium ion conductivity and electronic conductivity of the protective layer 20 may decrease, and the lithium metal layer 60 may not be formed uniformly.

[0042] The protective layer 20 may further contain a binder. The protective layer 20 may contain 1 to 5 parts by weight of the binder per 100 parts by weight of the matrix and the metal material combined. If the binder content is too high, it may hinder the movement of lithium ions within the protective layer 20.

[0043] The binder may include butadiene rubber, nitrile butadiene rubber, hydrogenated nitrile butadiene rubber, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), and the like.

[0044] The thickness of the protective layer 20 can be between 1 μm and 20 μm. If the thickness of the protective layer 20 is less than 1 μm, it will be difficult to fill the gap between the solid electrolyte layer 30 and the negative electrode current collector 10, and if it exceeds 20 μm, the energy density may decrease.

[0045] The solid electrolyte layer 30 is located between the positive electrode active material layer 40 and the negative electrode current collector 10 and is responsible for the movement of lithium ions.

[0046] The solid electrolyte layer 30 may contain a solid electrolyte that conducts lithium ions.

[0047] The solid electrolyte can include at least one selected from the group consisting of oxide-based solid electrolytes, sulfide-based solid electrolytes, polymer electrolytes, and combinations thereof. However, it is preferable to use a sulfide-based solid electrolyte with high lithium ion conductivity. The sulfide-based solid electrolyte is not particularly limited, but Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (where m, n are positive numbers, and Z is one of Ge, Zn, Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li x MO y (where x, y are positive numbers, and M is one of P, Si, Ge, B, Al, Ga, In), Li 10 GeP2S 12 and the like can be used.

[0048] The oxide-based solid electrolyte can include perovskite-type LLTO (Li 3x La 2 / 3-x TiO3), phosphate-based NASICON-type LATP (Li 1+x Al x Ti 2-x (PO4)3), etc.

[0049] The polymer electrolyte can include gel polymer electrolytes, solid polymer electrolytes, etc.

[0050] The solid electrolyte layer 30 can further contain a binder. The binder can include butadiene rubber, nitrile butadiene rubber, hydrogenated nitrile butadiene rubber, polyvinylidene difluoride (PVDF), polytetrafluoroethylene (PTFE), carboxymethylcellulose, etc.

[0051] The positive electrode active material layer 40 is configured to reversibly occlude and release lithium ions. The positive electrode active material layer 40 can include a positive electrode active material, a solid electrolyte, a conductive material, a binder, etc.

[0052] The positive electrode active material can be an oxide active material or a sulfide active material.

[0053] The oxide active material includes layered rock salt type active materials such as LiCoO2, LiMnO2, LiNiO2, LiVO2, Li 1+x Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O2, spinel type active materials such as LiMn2O4, Li(Ni 0.5 Mn 1.5 )O4, inverse spinel type active materials such as LiNiVO4, LiCoVO4, olivine type active materials such as LiFePO4, LiMnPO4, LiCoPO4, LiNiPO4, silicon-containing active materials such as Li2FeSiO4, Li2MnSiO4, and layered rock salt type active materials in which a part of the transition metal is replaced with a different metal such as LiNi 0.8 Co (0.2-x) Al x O2(0 < x < 0.2), and Li 1+x Mn 2-x-y M ySpinel-type active material in which part of the transition metal is substituted with a different metal such as O4 (M is at least one of Al, Mg, Co, Fe, Ni, Zn, and 0 < x + y < 2), Li4Ti5O 12 can be lithium titanate such as The sulfide active material can be copper chalcogenide, iron sulfide, cobalt sulfide, nickel sulfide, etc.

[0054] The solid electrolyte can include at least one selected from the group consisting of oxide-based solid electrolytes, sulfide-based solid electrolytes, polymer electrolytes, and combinations thereof. However, it is preferable to use a sulfide-based solid electrolyte having a high lithium ion conductivity. The sulfide-based solid electrolyte is not particularly limited, but Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (where m, n are positive numbers, Z is one of Ge, Zn, Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li x MO y (where x, y are positive numbers, M is one of P, Si, Ge, B, Al, Ga, In), Li 10 GeP2S 12 etc. can be used.

[0055] The oxide-based solid electrolyte can include perovskite-type LLTO (Li 3x La 2 / 3-x TiO3), phosphate-based NASICON-type LATP (Li 1+x Al x Ti 2-x (PO4)3), etc.

[0056] The aforementioned polymer electrolyte may include gel polymer electrolytes, solid polymer electrolytes, and the like.

[0057] The conductive material may include carbon black, conductive graphite, ethylene black, carbon fiber, graphene, and the like.

[0058] The binder may include butadiene rubber, nitrile butadiene rubber, hydrogenated nitrile butadiene rubber, polyvinylidene difluoride, polytetrafluoroethylene, carboxymethylcellulose, and the like.

[0059] The positive electrode current collector 50 may be a plate-shaped substrate having electrical conductivity. Specifically, the positive electrode current collector 50 may be in the form of a sheet or a thin film.

[0060] The anode current collector 50 may include at least one selected from the group consisting of indium, copper, magnesium, aluminum, stainless steel, iron, and combinations thereof.

[0061] A method for manufacturing an all-solid-state battery according to the present invention may include the steps of: mixing a metal sulfide and a carbon material and manufacturing a composite material by mechanical milling; manufacturing a slurry containing the composite material and a metal material capable of alloying with lithium; applying the slurry onto a substrate to form a protective layer; and manufacturing a laminate containing a negative electrode current collector, a protective layer located on the negative electrode current collector, a solid electrolyte layer located on the protective layer, a positive electrode active material layer located on the solid electrolyte layer, and a positive electrode current collector located on the positive electrode active material layer.

[0062] The conditions for mechanically milling the metal sulfide and carbon material are not particularly limited, and the process can be carried out under appropriate conditions such as rotation speed and time so that the composite has the aforementioned particle size (D50).

[0063] The specific methods of mechanical milling are not particularly limited and can be carried out by methods such as ball mill, airjet mill, bead mill, roll mill, planetary mill, hand mill, high energy ball mill, planetary ball mill, stirred ball mill, vibrating mill, mechanofusion milling, shaker milling, planetary milling and attritor milling, disk milling, shape milling, nauta milling, nobilta milling, and high-speed mix.

[0064] The metal sulfide used as the starting material can have a particle size (D50) of 0 nm to 50 μm. Since the metal sulfide is pulverized along the surface of the carbon material via mechanical milling, particles ranging from nano-size to bulk-size can be used.

[0065] The carbon material may include spherical particles with a particle size (D50) of 10 nm to 100 nm, or linear particles with a cross-sectional diameter of 10 nm to 300 nm. Since the particle size (D50) of the composite material is determined by the particle size (D50) of the carbon material, a carbon material of an appropriate size can be selected and used according to the desired particle size (D50) of the composite material.

[0066] The resulting composite material can be added to a solvent along with a metal material to obtain a slurry. A binder can be added at this time.

[0067] The solvent is not particularly limited and may include any solvent commonly used in the art to which the present invention pertains. For example, the solvent may include n-methyl-2-pyrrolidone (NMP), water, ethanol, isopropanol, and the like.

[0068] The slurry can be applied to a substrate to form a protective layer. In this case, the substrate may be a negative electrode current collector. However, the manufacturing method is not limited to this, and other methods are also possible, such as forming a protective layer on a separate substrate, such as release paper, and then transferring it onto the negative electrode current collector.

[0069] The method for forming the laminate is not particularly limited. Each component can be formed simultaneously or at different times. Furthermore, the manufacturing method may include not only directly forming a solid electrolyte layer on a protective layer, a positive electrode active material layer on a solid electrolyte layer, and a positive electrode current collector on a positive electrode active material layer, but also manufacturing each component separately and then laminating them in the structure shown in Figure 1.

[0070] Other embodiments of the present invention will be described in more detail below by examples. The following examples are merely illustrative to aid in understanding the present invention and do not limit the scope of the invention.

[0071] Example 1 A composite material was obtained by mixing MoS2, a metal sulfide, with carbon black, a carbon material, and then mechanically milling the mixture. The mass ratio of the metal sulfide to the carbon material was 3:7. Figure 3 shows the results of scanning electron microscopy with Engery Dispersive Spectroscopy (SEM-EDS) analysis of the composite material. Referring to this, it can be seen that Mo, S, and C are uniformly distributed in the composite material.

[0072] The composite material was added to a solvent together with a metal material (Ag) and a binder (polyvinylidene fluoride (PVDF)) to obtain a slurry. 70% by weight of the composite material and 30% by weight of the metal material were added. Furthermore, approximately 5 parts by weight of the binder was added to 100 parts by weight of the combined composite material and metal material. n-methyl-2-pyrrolidone (NMP) was used as the solvent.

[0073] The slurry was applied to the negative electrode current collector and dried to form a protective layer. Figure 4 shows the results of scanning electron microscope-X-ray spectroscopy (SEM-EDS) analysis of the protective layer. Referring to this, it can be seen that the metallic material Ag is uniformly dispersed within the matrix made of the composite material.

[0074] Comparative Example Instead of manufacturing composite materials, we use 70% carbon black, which is a carbon material, as a metal material. (silver) A protective layer was formed in the same manner as in Example 1, except that it was prepared by mixing with 30% by weight.

[0075] Figure 5 shows the results of scanning electron microscopy (SEM) analysis of a cross-section of a half-cell with the protective layer introduced according to Example 1 after initial deposition. The current density is 1.17 mA / cm². 2 The deposition capacity is 3.525 mAh / cm². 2The evaluation temperature is 30°C. It can be confirmed that lithium is uniformly deposited and formed on the negative electrode current collector. Uniform lithium deposition is induced by an alloy reaction with Ag, a lithium-affinity metal material. In addition, the composite material containing MoS2 and carbon material acts as a transport channel for lithium ions, efficiently moving lithium ions from low to high temperatures.

[0076] Figure 6 shows the initial charge and discharge results of a half-cell with a protective layer introduced according to Example 1. Figure 7 shows the initial charge and discharge results of a half-cell with a protective layer introduced according to a comparative example. Referring to Figure 6, when the metal sulfide MoS2 is introduced, a capacity of approximately 0.5 mAh is achieved at 0.6 V during the discharge process, both at room temperature and high temperature. This is because MoS2 + Li is present around a voltage of 0.6 V. + →This indicates that the Mo+Li2S reaction occurs, allowing lithium ions to move within the protective layer. Referring to Figure 7, the non-ideal behavior is observed where the amount desorbed is even greater than the amount deposited during operation at room temperature, which means that a cell short circuit occurred. In other words, the half-cell of Example 1 is more stable in charge and discharge than the comparative example, because the initial conversion reaction of the metal sulfide improves lithium ion conductivity at room temperature.

[0077] Figure 8 shows the charge-discharge cycle graph of the half-cell with the protective layer introduced according to Example 1. The current density is 1.17 mA / cm². 2 The deposition capacity is 3.525 mAh / cm². 2 The evaluation was conducted as follows: Up to 50 cycles, the average Coulomb efficiency approached 100% at all temperatures from room temperature (30°C) to high temperature (60°C), demonstrating stable life characteristics and efficiency. This proves that the Ag present in the protective layer effectively induces lithium, and the composite material provides a lithium ion diffusion pathway, thereby facilitating lithium ion movement.

[0078] Example 2 A protective layer was formed in the same manner as in Example 1, except that the mass ratio of metal sulfide to carbon material in the composite material was adjusted to 2:8.

[0079] Figure 9a shows the charge-discharge cycle graph of the half-cell with the protective layer introduced in Example 2. Figure 9b shows the initial charge-discharge graph of the half-cell with the protective layer introduced in Example 2. Example 2 also shows stable cycle characteristics, similar to Example 1. This means that the composite material in the protective layer provides sufficient diffusion pathways for lithium ions. This indicates that it is necessary to keep the mass ratio of metal sulfides in the composite material to 5 or less, and that performance can be further improved by adjusting the mass ratio of metal sulfides to carbon material.

[0080] Example 3 A protective layer was formed in the same manner as in Example 1, except that vapor-grown carbon fibers (VGCF) were used as the carbon material.

[0081] Example 4 The protective layer was formed in the same manner as in Example 1, except that multi-wall carbon nanotubes were used as the carbon material.

[0082] Figure 10 shows the charge-discharge cycle graph of a half-cell with the protective layer introduced according to Example 3. Figure 11 shows the charge-discharge cycle graph of a half-cell with the protective layer introduced according to Example 4. The current density is 1.17 mA / cm². 2 The deposition capacity is 3.525 mAh / cm². 2 The evaluation was then conducted.

[0083] It can be confirmed that the cells operate stably for each type of carbon material.

[0084] Although embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to the embodiments described above, and various modifications and improvements by those skilled in the art using the basic concepts of the present invention as defined in the following claims are also included in the scope of the present invention. [Explanation of symbols]

[0085] 10 Negative electrode current collector 20 protective layer 30 Solid electrolyte layer 40 Cathode active material layer 50 Anode current collector 60 Lithium metal layer

Claims

1. A negative electrode current collector; a protective layer located on the negative electrode current collector; a solid electrolyte layer located on the protective layer; a positive electrode active material layer located on the solid electrolyte layer; and a positive electrode current collector located on the positive electrode active material layer; The aforementioned protective layer is A matrix consisting of a composite material containing metal sulfides and carbon materials; A solid-state battery comprising: a metallic material dispersed in the matrix and capable of being alloyed with lithium; The metal sulfide includes a compound represented by M x S y (where M is at least one selected from the group consisting of Mo, W, Cu, Co, Ti, Ni, Fe and combinations thereof, satisfying 1 ≤ x ≤ 3 and 0.5 ≤ y ≤ 4), The aforementioned metal material includes at least one selected from the group consisting of Ag, Zn, Mg, Bi, Sn, and combinations thereof. The protective layer comprises, based on the total mass of the protective layer, 50% to 80% by weight of the matrix and 20% to 50% by weight of the metal material. All-solid-state battery.

2. The all-solid-state battery according to claim 1, wherein the carbon material includes spherical carbon with a particle size (D50) of 10 nm to 100 nm, or linear carbon with a cross-sectional diameter of 10 nm to 300 nm.

3. The all-solid-state battery according to claim 1, wherein the carbon material comprises at least one selected from the group consisting of carbon black, carbon nanotubes, carbon fibers, vapor-grown carbon fibers, and combinations thereof.

4. The all-solid-state battery according to claim 1, wherein the particle size (D50) of the composite material is 10 nm to 1 μm.

5. The all-solid-state battery according to claim 1, wherein the composite material contains a metal sulfide and a carbon material in a mass ratio of 2:8 to 5:

5.

6. The all-solid-state battery according to claim 1, wherein the particle size (D50) of the metal material is 30 nm to 500 nm.

7. The all-solid-state battery according to claim 1, wherein the protective layer has a thickness of 1 μm to 20 μm.

8. During charging and discharging, the metal sulfide reacts with lithium ions to form lithium sulfide (Li ２ The all-solid-state battery according to claim 1, wherein S) and a metal are converted, and lithium is stored between the negative electrode current collector and the protective layer.

9. The process involves mixing metal sulfides and carbon materials and manufacturing a composite material by mechanical milling, A step of producing a slurry containing the aforementioned composite material and a metal material that can be alloyed with lithium, The steps include applying the slurry onto a substrate to form a protective layer, A step of manufacturing a laminate including a negative electrode current collector, a protective layer located on the negative electrode current collector, a solid electrolyte layer located on the protective layer, a positive electrode active material layer located on the solid electrolyte layer, and a positive electrode current collector located on the positive electrode active material layer, Includes, The aforementioned protective layer is A matrix consisting of a composite material containing metal sulfides and carbon materials, The matrix contains a metallic material that is dispersed and capable of being alloyed with lithium, A method for manufacturing an all-solid-state battery, The metal sulfide includes a compound represented by M x S y (where M is at least one selected from the group consisting of Mo, W, Cu, Co, Ti, Ni, Fe and combinations thereof, satisfying 1 ≤ x ≤ 3 and 0.5 ≤ y ≤ 4), The aforementioned metal material includes at least one selected from the group consisting of Ag, Zn, Mg, Bi, Sn, and combinations thereof. The protective layer comprises, based on the total mass of the protective layer, 50% to 80% by weight of the matrix and 20% to 50% by weight of the metal material. A method for manufacturing all-solid-state batteries.

10. The method for manufacturing an all-solid-state battery according to claim 9, wherein the particle size (D50) of the metal sulfide is 10 nm to 50 μm.

11. The method for manufacturing an all-solid-state battery according to claim 9, wherein the carbon material includes spherical carbon with a particle size (D50) of 10 nm to 100 nm, or linear carbon with a cross-sectional diameter of 10 nm to 300 nm.

12. The method for manufacturing an all-solid-state battery according to claim 11, wherein the carbon material comprises at least one selected from the group consisting of carbon black, carbon nanotubes, carbon fibers, vapor-grown carbon fibers, and combinations thereof.

13. The method for manufacturing an all-solid-state battery according to claim 9, wherein the particle size (D50) of the composite material is 10 nm to 1 μm.

14. The method for manufacturing an all-solid-state battery according to claim 9, wherein the composite material contains a metal sulfide and a carbon material in a mass ratio of 2:8 to 5:

5.

15. The method for manufacturing an all-solid-state battery according to claim 9, wherein the particle size (D50) of the metal material is 30 nm to 500 nm.

16. The method for manufacturing an all-solid-state battery according to claim 9, wherein the protective layer has a thickness of 1 μm to 20 μm.

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