All-solid-state battery

Abstract

Disclosed is an all-solid-state battery comprising a positive electrode including a positive electrode active material; a negative electrode; a solid electrolyte layer disposed between the positive electrode and the negative electrode; and an interlayer disposed between the positive electrode and the solid electrolyte layer, the positive electrode active material comprising a composite of a sulfur-based material, metal halide salts, and a carbon-based material, wherein the sulfur-based material includes at least one of S8 and Li2Sn(1 ≤ n ≤ 8, where n is an integer), the metal halide salts comprises a first metal halide salt including an alkali metal, and a second metal halide salt including a boron group metal, and the interlayer comprises a compound represented by chemical formula 1 below and a first sulfide-based solid electrolyte. [Chemical formula 1] LiaFe1-xMxPO4

Description

All-solid-state battery

[0001] This is about all-solid-state batteries.

[0002]

[0003] Recently, driven by industrial demands, the development of batteries with high energy density and safety is actively underway. For example, rechargeable batteries are used in a wide range of applications, including information devices, communication equipment, and automobiles. Since automobiles are a matter of life and death, safety is also critical.

[0004] Secondary batteries using liquid electrolytes may have an increased risk of fire and / or explosion in the event of a short circuit. Solid-state batteries employing solid electrolytes instead of liquid electrolytes are being proposed. Solid electrolytes have a lower risk of ignition compared to liquid electrolytes.

[0005]

[0006] One aspect is to provide a cathode that simultaneously offers improved charge / discharge characteristics and thermal stability by introducing a protective layer containing an oxide-based cathode active material between a cathode active material layer containing a sulfide-based cathode active material and a cathode current collector.

[0007]

[0008] According to one embodiment, the apparatus comprises: a positive electrode including a positive active material; a negative electrode; a solid electrolyte layer disposed between the positive electrode and the negative electrode; and an interlayer disposed between the positive electrode and the solid electrolyte layer, wherein the positive active material comprises a composite of a sulfur-based material, a metal halide salt, and a carbon-based material, and the sulfur-based material comprises S8 and Li2S nAn all-solid-state battery is provided, comprising at least one of (1 ≤ n ≤ 8, where n is an integer), wherein the metal halide salt comprises a first metal halide salt comprising an alkali metal and a second metal halide salt comprising a boron group metal, and the intermediate layer comprises a compound represented by the following chemical formula 1 and a first sulfide-based solid electrolyte.

[0009] [Chemical Formula 1]

[0010] Li a Fe 1-x M x PO4

[0011] (In the above chemical formula 1, 0.90 ≤ a ≤ 1.8, 0 ≤ x ≤ 0.7, M is Mn, Mg, Co, Ni, or a combination thereof).

[0012]

[0013] According to one aspect, it is possible to provide a positive electrode and an all-solid-state secondary battery having improved charge / discharge characteristics and thermal stability simultaneously by introducing a protective layer containing an oxide-based positive electrode active material between a positive electrode active material layer containing a sulfide-based positive electrode active material and a positive electrode current collector.

[0014]

[0015] FIG. 1 is a cross-sectional view of an all-solid-state battery according to an exemplary embodiment.

[0016] Figure 2 is a schematic cross-sectional view showing an enlarged view of area A of Figure 1.

[0017] Figure 3 is a schematic cross-sectional view showing an enlarged view of area B of Figure 2.

[0018] Figure 4 is a schematic cross-sectional view showing an enlarged view of area C of Figure 1.

[0019] FIG. 5 is a cross-sectional view of an all-solid-state battery according to an exemplary embodiment.

[0020] FIG. 6 is a cross-sectional view of an all-solid-state battery according to an exemplary embodiment.

[0021] FIG. 7 is a cross-sectional view of an all-solid-state battery according to an exemplary embodiment.

[0022]

[0023] The present inventive concept described below is subject to various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present inventive concept to specific embodiments and should be understood to include all modifications, equivalents, or substitutions that fall within the scope of the description of the present inventive concept.

[0024] The terms used below are used merely to describe specific embodiments and are not intended to limit the creative concept. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the following, terms such as “comprising” or “having” are intended to indicate the existence of the features, numbers, steps, actions, components, parts, components, materials, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, components, materials, or combinations thereof. The “ / ” used below may be interpreted as “and” or “or” depending on the context.

[0025] In the drawings, thicknesses have been enlarged or reduced to clearly represent various layers and regions. Throughout the specification, the same reference numerals have been used for similar parts. Throughout the specification, when a part such as a layer, film, region, or plate is described as being “on” or “above” another part, this includes not only cases where it is directly above another part but also cases where there is another part in between. Throughout the specification, terms such as “first,” “second,” etc., may be used to describe various components, but the components should not be limited by these terms. In this specification and drawings, components having substantially the same functional configuration are referred to by the same reference numerals to avoid redundant descriptions.

[0026] In the present disclosure, the “size” of a particle is, for example, the “particle diameter” of the particle. The “particle diameter” of the particle represents the average diameter when the particle is spherical and represents the average major axis length when the particle is non-spherical. The particle diameter of the particle can be measured using a particle size analyzer (PSA). The “particle diameter” of the particle is, for example, the average particle diameter. The average particle diameter is, for example, the median particle diameter (D50). The median particle diameter (D50) is the particle size corresponding to the 50% cumulative volume calculated from the side of the particle having a small particle size in the particle size distribution measured, for example by laser diffraction.

[0027] In the present disclosure, “metal” includes both metals and metalloids such as silicon and germanium in an elemental or ionic state.

[0028] In this disclosure, “alloy” means a mixture of two or more metals.

[0029] In the present disclosure, “anode active material” refers to an anode material capable of undergoing lithiation and delithiation.

[0030] In the present disclosure, “anode active material” refers to an anode material capable of undergoing lithiation and delithiation.

[0031] In the present disclosure, “lithiation” and “to lithiate” refer to the process of adding lithium to a positive electrode active material or a negative electrode active material.

[0032] In the present disclosure, “delithiation” and “to delithiate” refer to the process of removing lithium from a positive electrode active material or a negative electrode active material.

[0033] In this disclosure, “charge” and “to charge” refer to the process of providing electrochemical energy to a battery.

[0034] In this disclosure, “anode” and “cathode” refer to electrodes where electrochemical reduction and lithiation occur during the discharge process.

[0035] In this disclosure, “cathode” and “anode” refer to electrodes where electrochemical oxidation and delithiation occur during the discharge process.

[0036] In the present disclosure, "dry" or "dry" means a state in which a solvent, such as a process solvent, is not intentionally in contact with or is not intentionally contained with a solvent. For example, a dry electrode active material means an electrode active material that is not intentionally in contact with a solvent or an electrode active material that is not intentionally contained with a solvent. For example, a dry conductive material means a conductive material that is not intentionally in contact with a solvent or a conductive material that is not intentionally contained with a solvent. For example, a dry binder means a conductive material that is not intentionally in contact with a solvent or a binder that is not intentionally contained with a solvent. For example, a binder that is in a liquid state at room temperature and does not mix with a solvent is a dry binder.

[0037] A solid-state battery according to exemplary embodiments is described in more detail below.

[0038] FIG. 1 is a cross-sectional view of an all-solid-state battery (10) according to an exemplary embodiment.

[0039] Referring to FIG. 1, an all-solid-state battery (10) according to an exemplary embodiment may include a positive electrode (100) containing a positive active material, a negative electrode (200), a solid electrolyte layer (300) disposed between the positive electrode (100) and the negative electrode (200), and an interlayer (400) disposed between the positive electrode (100) and the solid electrolyte layer (300).

[0040] Referring to FIG. 1, the positive electrode (100) may include a positive electrode current collector (110) and a positive electrode active material layer (120) disposed on one or both sides of the positive electrode current collector (110).

[0041] The positive current collector (110) can provide a reference surface on which the positive active material layer (120) is placed. The positive current collector (110) may include, for example, a plate or foil comprising indium (In), copper (Cu), magnesium (Mg), stainless steel (SUS), titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

[0042] In other embodiments, the positive current collector (110) may be omitted. Although not illustrated, a carbon layer with a thickness of 0.1 μm to 4 μm may be further disposed between the positive current collector (110) and the positive active material layer (120) to increase the bonding strength between the positive current collector (110) and the positive active material layer (120). The carbon layer may include amorphous carbon, crystalline carbon, etc.

[0043] FIG. 2 is a schematic cross-sectional view showing an enlarged view of region A of the positive active material layer (120) of FIG. 1. Referring to FIG. 2, the positive active material layer (120) according to one embodiment may include a positive active material (10), a second sulfide-based solid electrolyte (22), a conductive material (30), and a second binder (42). Unlike what is shown, in an exemplary embodiment, the conductive material (30) may be omitted from the positive active material layer (120).

[0044] The positive active material (10) may contain elemental sulfur (S). Sulfur is attracting attention as a next-generation positive material because it has a high theoretical capacity (1,672 mAh / g), is abundant on Earth, and is relatively inexpensive. In one embodiment, the elemental sulfur (S) is S8 and Li2S n It may exist in the form of a sulfur-based material comprising at least one of (1 ≤ n ≤ 8, where n is an integer). The positive active material layer (120) may include a second sulfide-based solid electrolyte (22) to form an ion conduction path (R1).

[0045] The positive active material (10) according to one embodiment may have relatively excellent ionic conductivity. The ionic conductivity of the positive active material (10) according to one embodiment is 3 x 10 at 25 ℃. -6 It can be greater than S / cm. For example, the ionic conductivity of the positive active material (10) is 3.5 x 10 -6 It may be greater than S / cm, and 4 x 10 -6 It may be greater than S / cm, and 5 x 10 -6 It may be greater than S / cm, and 6 x 10 -6 It may be greater than S / cm, and 6.75 x 10 -6 It may be greater than S / cm. The ionic conductivity of the positive active material (10) according to one embodiment is 1 x 10 -4It may be less than S / cm. Ionic conductivity can be measured using a DC polarization method. Alternatively, ionic conductivity can be measured using a complex impedance method. Referring to FIG. 2, since the positive active material (10) according to one embodiment has excellent ionic conductivity, an ionic conduction path (R1) passing through the second sulfide-based solid electrolyte (22) - positive active material (10) - second sulfide-based solid electrolyte (22) can be formed. Accordingly, the ionic conductivity of the positive active material layer (120) is improved, and the energy density of the all-solid-state battery (10) containing it can be improved.

[0046] FIG. 3 is an enlarged view illustrating a positive active material (10) according to an exemplary embodiment. In FIG. 3, the area corresponding to region B of FIG. 2 is illustrated in an enlarged manner. Hereinafter, the positive active material (10) according to the embodiment will be described in detail with reference to FIG. 3.

[0047] Referring to FIG. 3, the positive active material (10) according to the embodiment may include a composite of a sulfur-based material (1), a metal halide salt (2, 3), and a carbon-based material (4).

[0048] The positive active material (10) may, for example, have a particle form. The particle size of the positive active material (10), that is, the size of the composite particle, may be, for example, 50 μm or less, 30 μm or less, or 10 μm or less. The size of the composite particle may be, for example, 0.1 μm to 50 μm or 1 μm to 10 μm. As the composite particle has a size within this range, the volume change during charging and discharging is suppressed, thereby suppressing the degradation of the positive active material (10) containing the composite during charging and discharging. If the size of the composite particle increases excessively, the volume change of the composite during charging and discharging increases, thereby promoting the degradation of the positive active material (10) containing the composite. Accordingly, a secondary battery containing a positive active material (10) in which the size of the composite particle is within the above range may have improved cycle characteristics and lifespan characteristics.

[0049] The size of the composite particles can be, for example, the particle diameter of the composite. The particle diameter of the composite can be measured using, for example, laser diffraction, scanning electron microscopy, etc. The particle diameter of the composite is, for example, the arithmetic mean of the particle diameters of multiple particles measured using software from a scanning electron microscopy image.

[0050] The positive active material (10) may include a sulfur-based material (1). The sulfur-based material (1) is S8 and Li2S n It may include at least one of (1 ≤ n ≤ 8, where n is an integer). A continuous oxidation / reduction reaction of sulfur and / or lithium sulfide proceeds in the sulfur-based material (1). For example, the reaction process of lithium polysulfide and lithium sulfide by the continuous reduction reaction of sulfur in the sulfur-based material (1) can be expressed as S8→Li2S8→Li2S6→Li2S4→Li2S2→Li2S, etc. In this process, lithium ions move between the anode and cathode, and at the same time, electrons move through an external circuit to generate an electric current.

[0051] The content of the sulfur-based material (1) may be 20 to 80 weight% with respect to the total weight of the composite. For example, according to one embodiment, the content of the sulfur-based material (1) may be 30 to 70 weight% or 35 to 60 weight% with respect to the total weight of the composite.

[0052] The positive active material (10) may include metal halide salts (2, 3). The metal halide salts (2, 3) may include a first metal halide salt (2) containing an alkali metal and a second metal halide salt (3) containing a boron group metal. According to one embodiment, the metal halide salts (2, 3) may form a composite with the sulfur-based material (1) described above.

[0053] The content of the metal halide salt (2, 3) may be 10 to 60 weight% with respect to the total weight of the composite. For example, according to one embodiment, the content of the metal halide salt (2, 3) may be 20 to 50 weight% or 25 to 45 weight% with respect to the total weight of the composite.

[0054] The first metal halide salt (2) may be a binary compound composed of, for example, an alkali metal and one element selected from Group 17 of the periodic table. The first metal halide salt (2) may be, for example, a lithium salt. The first metal halide salt (2) may include, for example, LiF, LiCl, LiBr, LiI, or a combination thereof. This first metal halide salt (2) can form a composite with a sulfur-based material (1) to improve the ionic conductivity of a positive electrode active material (10) containing the sulfur-based material (1). This first metal halide salt (2) can more easily form a solid solution with the sulfur-based material (1) within the composite.

[0055] According to one embodiment, the content of the first metal halide salt (2) may be 2.5 to 15 weight% with respect to the total weight of the composite. For example, according to one embodiment, the content of the first metal halide salt (2) may be 5 to 12.5 weight% or 7 to 10 weight% with respect to the total weight of the composite.

[0056] In one embodiment, the positive active material (10) may have a weight ratio of the sulfur-based material (1) to the first metal halide salt (2) of 30:1 to 1:1. For example, in one embodiment, the positive active material (10) may have a weight ratio of the sulfur-based material (1) to the first metal halide salt (2) of 20:1 to 2:1 or 10:1 to 3:1.

[0057] The second metal halide salt (3) may be a binary compound composed of, for example, a boron group metal and one element selected from Group 17 of the periodic table. The second metal halide salt (3) may include, for example, AlF3, AlCl3, AlBr3, AlI3, GaF3, GaCl3, GaBr3, GaI3, InF3, InCl3, lnBr3, lnI3, TiF3, TiCl3, TiBr3, TiI3, or a combination thereof. This second metal halide salt (3) can form a composite with the sulfur-based material (1) and the first metal halide salt (2) to maintain the overall shape of the positive active material (10) containing the sulfur-based material (1) and the first metal halide salt (2) and to lower the interfacial resistance. This second metal halide salt (3) can more easily form a solid solution with the sulfur-based material (1) and the first metal halide salt (2) within the composite, for example. The positive active material (10) containing this second metal halide salt (3) can improve the capacity characteristics of the battery by suppressing the leaching of lithium polysulfide (Li2Sx).

[0058] According to one embodiment, the content of the second metal halide salt (3) may be 7.5 to 45 weight% with respect to the total weight of the composite. For example, according to one embodiment, the content of the second metal halide salt (3) may be 15 to 37.5 weight% or 20 to 31 weight% with respect to the total weight of the composite.

[0059] In one embodiment, the positive active material (10) may have a weight ratio of the sulfur-based material (1) to the second metal halide salt (3) of 10:1 to 1:1. For example, in one embodiment, the positive active material (10) may have a weight ratio of the sulfur-based material (1) to the second metal halide salt (3) of 5:1 to 1:1 or 5:1 to 2:1.

[0060] The positive electrode active material (10) may include different types of metal halide salts (2, 3). The different types of metal halide salts (2, 3) may include the first metal halide salt (2) and the second metal halide salt (3) described above. The positive electrode active material (10) according to the embodiment includes different types of metal halide salts (2, 3) to improve ion conductivity while maintaining the overall shape and reducing interfacial resistance, and can improve the capacity characteristics of the battery by suppressing the leaching of lithium polysulfide (Li2Sx).

[0061] In one embodiment, the positive active material (10) may have a weight ratio of the first metal halide salt (2) and the second metal halide salt (3) of 5:1 to 1:20. For example, the weight ratio of the first metal halide salt (2) and the second metal halide salt (3) may be 3:1 to 1:9, 1:1 to 1:9, or 1:3 to 1:9. The positive active material (10) satisfying the above range may include different types of metal halide salts (2, 3) in appropriate proportions to maximize the effect of improving the capacity characteristics described above.

[0062] A composite according to one embodiment may include a solid solution of the aforementioned sulfur-based material (1) and metal halide salts (2, 3).

[0063] According to one embodiment, the ionic conductivity of the composite may be increased by including a solid solution of a sulfur-based material (1) and a first metal halide salt (2). For example, since the solid solution of the sulfur-based material (1) and the first metal halide salt (2) contains alkali metal ions disposed within the crystallites of the sulfur-based material (1), the ionic conductivity of the solid solution of the sulfur-based material (1) and the first metal halide salt (2) may be improved compared to the ionic conductivity of the sulfur-based material (1). Consequently, the ionic conductivity of the composite may be improved and the internal resistance of the composite may be reduced. By including such a composite in the positive active material (10), the cycle characteristics of the secondary battery containing the positive active material (10) may be improved. For example, the high-rate characteristics of the secondary battery containing such a positive active material (10) may be improved.

[0064] According to one embodiment, the composite can maintain its overall shape and lower interfacial resistance by including a solid solution of a sulfur-based material (1) and a second metal halide salt (3). For example, since the solid solution of the sulfur-based material (1) and the second metal halide salt (3) maintains the overall shape of the composite, the sulfur-based material (1) undergoes oxidation / reduction to produce S8 and Li2S n Even if the shape is deformed between (1 ≤ n ≤ 8, where n is an integer), the shape deformation of the composite and the positive active material (10) can be minimized. By including such a composite in the positive active material (10), the shape deformation during the charging / discharging process can be minimized, thereby improving cycle characteristics.

[0065] A solid solution according to one embodiment is (1-xy)Li2S nIt may include -xAX-yBX3 or (1-xy)S8-xAX-yBX3. The x and the y are 0.01 < x < 0.3 and 0.01 < y < 0.3, and the n is an integer such that 1 ≤ n ≤ 8, the A is an alkali metal, the B is a boron group metal, and the X is a halogen element.

[0066] The positive active material (10) may include a carbon-based material (4). The carbon-based material (4) may form a composite with the aforementioned sulfur-based material (1) and metal halide salts (2, 3). The composite of the carbon-based material (4), the sulfur-based material (1), and the metal halide salts (2, 3) is distinguished from a simple mixture of the carbon-based material (4), the sulfur-based material (1), and the metal halide salts (2, 3). A simple mixture of the carbon-based material (4), the sulfur-based material (1), and the metal halide salts (2, 3) fails to maintain a dense interface between the carbon-based material (4), the sulfur-based material (1), and the metal halide salts (2, 3), resulting in high interfacial resistance and consequently degrading the lifespan characteristics of the secondary battery.

[0067] The carbon-based material (4) may be any material containing carbon atoms, for example, used as a conductive material in the relevant technical field. The carbon-based material (4) may include, for example, crystalline carbon, amorphous carbon, or a combination thereof. The carbon-based material (4) may include, for example, a calcined product of a carbon precursor. The carbon-based material (4) may be, for example, a carbon nanostructure. The carbon nanostructure may include, for example, a one-dimensional carbon nanostructure, a two-dimensional carbon nanostructure, a three-dimensional carbon nanostructure, or a combination thereof. The carbon nanostructure may include, for example, carbon nanotubes (CNT), carbon nanofibers (CNF), carbon nanobelts, carbon nanorods, graphene, or a combination thereof. The carbon-based material (4) may be, for example, a porous carbon-based material or a non-porous carbon-based material. The porous carbon-based material may include, for example, periodic and regular two-dimensional or three-dimensional pores. The porous carbon-based material may include, for example, carbon black such as Ketjen black, acetylene black, Denka black, thermal black, and channel black, graphite, activated carbon, or a combination thereof. The form of the carbon-based material (4) may be, for example, particle form, sheet form, flake form, etc., but is not limited to these, and any form used as a carbon-based material (4) in the relevant technical field is possible.

[0068] The carbon-based material (4) according to one embodiment may include, for example, a fibrous carbon-based material (4). By including the fibrous carbon-based material (4) in the composite, the electron conductivity of the composite may be further improved. By including the fibrous carbon-based material (4) in the composite, electron conduction from the surface to the interior of the composite may be performed more easily. The internal resistance of the positive active material (10) including such a composite is reduced, and the cycle characteristics of the secondary battery including the positive active material (10) may be further improved.

[0069] The aspect ratio of the fibrous carbon-based material may be, for example, 2 or more, 3 or more, 4 or more, 5 or more, 10 or more, or 20 or more. The aspect ratio of the fibrous carbon-based material may be, for example, 2 to 30, 3 to 30, 4 to 30, 5 to 30, 10 to 30, or 20 to 30. The aspect ratio of the fibrous carbon-based material may be, for example, 2 to 30, 2 to 20, 2 to 10, 2 to 8, 2 to 5, or 2 to 4. By having the fibrous carbon-based material have an aspect ratio within this range, the overall electronic conductivity of the composite is improved, and the imbalance of local electronic conductivity within the composite can be further alleviated.

[0070] The diameter of the fibrous carbon-based material may be, for example, 0.01 μm to 10 μm, 0.05 μm to 10 μm, or 0.1 μm to 5 μm. The length of the fibrous carbon-based material may be, for example, 1 μm to 50 μm or 1 μm to 20 μm. The diameter and length of the fibrous carbon-based material may be measured from scanning electron microscope (SEM) or transmission electron microscope (TEM) images. Alternatively, the diameter and / or length of the fibrous carbon-based material may be measured by laser diffraction.

[0071] According to one embodiment, the content of the carbon-based material (4) may be 1 to 30 weight% with respect to the total weight of the composite. For example, according to one embodiment, the content of the carbon-based material (4) may be 1 to 20 weight%, 5 to 20 weight%, or 10 to 20 weight% with respect to the total weight of the composite. If the content of the carbon-based material (4) increases excessively, the energy density of the battery may decrease. If the content of the carbon-based material (4) decreases excessively, the electronic conductivity of the composite decreases, and the internal resistance of the positive active material (10) may increase. A battery comprising a positive active material (10) that satisfies the content range of the carbon-based material (4) may have improved cycle characteristics.

[0072] The positive active material (10) according to one embodiment may have relatively excellent electron conductivity by including the carbon-based material (4) described above. The electron conductivity of the positive active material (10) according to one embodiment at 25°C is 5 x 10 -3 It can be greater than S / cm. For example, the electron conductivity of the positive active material (10) is 6.5 x 10 -3 It may be greater than S / cm, and 7 x 10 -3 It may be greater than S / cm, and 8 x 10 -3 It may be greater than S / cm. The electron conductivity of the positive active material (10) according to one embodiment is 1 x 10 -1 It may be less than S / cm.

[0073] The pellet density of the positive active material (10) according to one embodiment may be 1.5 g / cc or higher. For example, the pellet density of the positive active material (10) according to one embodiment may be 1.6 g / cc or higher, 1.62 g / cc or higher, 1.64 g / cc or higher, or 1.7 g / cc or higher. A secondary battery comprising a positive active material (10) satisfying the above range may have improved energy density. The pellet density of the positive active material (10) according to one embodiment may be 5 g / cc or lower, 4 g / cc or lower, or 3 g / cc or lower.

[0074] According to one embodiment, the content of the positive active material (10) may include 40 to 90 parts by weight per 100 parts by weight of the positive active material layer (120). For example, according to one embodiment, the content of the positive active material (10) may include 50 to 85 parts by weight, 60 to 80 parts by weight, or 65 to 75 parts by weight per 100 parts by weight of the positive active material layer (120). When satisfying the above ranges, the secondary battery according to one embodiment may have excellent capacity characteristics.

[0075] The second sulfide-based solid electrolyte (22) can provide an ion transfer pathway within the positive active material layer (120). The positive active material layer (120) according to an embodiment may have a further reduced internal resistance by including the positive active material (10) described above and the second sulfide-based solid electrolyte (22).

[0076] The second sulfide-based solid electrolyte (22) may have a particle shape. The second sulfide-based solid electrolyte (22) may be dispersed among the positive active materials (10). The second sulfide-based solid electrolyte (22) may have excellent lithium ion conductivity characteristics. The second sulfide-based solid electrolyte (22) is, for example, Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m, n are positive numbers, uppercase “Z” is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, uppercase “M” is one of P, Si, Ge, B, Al, Ga, In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may include at least one selected from (0≤x≤2).

[0077] The second sulfide-based solid electrolyte (22) is, for example, Li 7-x PS 6-x Cl x(0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may be an argyrodite-type compound comprising one or more selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I. The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. By having a density of 1.5 g / cc or more for the argyrodite-type solid electrolyte, the internal resistance of the all-solid-state battery (10) is reduced, and defects such as penetration and short circuit of the solid electrolyte film due to lithium dendrite formation can be prevented. The elastic modulus of the solid electrolyte may be, for example, 15 GPa to 35 GPa.

[0078] According to one embodiment, the content of the second sulfide-based solid electrolyte (22) may include 10 to 60 parts by weight per 100 parts by weight of the positive active material layer (120). For example, according to one embodiment, the content of the second sulfide-based solid electrolyte (22) may include 15 to 50 parts by weight, 20 to 40 parts by weight, or 25 to 35 parts by weight per 100 parts by weight of the positive active material layer (120). When satisfying the above ranges, the secondary battery according to one embodiment may have excellent capacity characteristics.

[0079] The conductive material (30) according to one embodiment may include a material identical to or different from the carbon-based material (4) described above. Unlike the carbon-based material (4) which forms a composite with the sulfur-based material (1) and metal halide salts (2, 3) within the positive active material (10), the conductive material (30) according to one embodiment may exist within the positive active material layer (120) as an independent composition. The conductive material (30) according to one embodiment may be omitted. The content of the conductive material (30) according to one embodiment may include 0 to 10 parts by weight per 100 parts by weight of the positive active material layer (120). For example, the content of the conductive material (30) according to one embodiment may include 0 to 5 parts by weight per 100 parts by weight of the positive active material layer (120). When satisfying the above range, the secondary battery according to one embodiment may have excellent capacity characteristics.

[0080] A second binder (42) according to one embodiment may include a dry binder. The dry binder may be, for example, a binder that is not impregnated, dissolved, or dispersed in a solvent. The dry binder may be, for example, a binder that contains a solvent or does not come into contact with a solvent.

[0081] The dry binder may include, for example, a fibrillized binder. The fibrillized binder may serve as a matrix that supports and binds the dry electrode active material and / or other components contained in the dry electrode film. The fibrillized binder can be confirmed to have a fibrous form, for example, by scanning electron microscope images of the dry electrode film or electrode cross-section. The fibrillated binder may have an aspect ratio of, for example, 10 or more, 20 or more, 50 or more, or 100 or more. The dry binder may be, for example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride-hexapropylene (PVDF-HFP) copolymer, polyvinylidene fluoride (PVDF), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, cellulose, polyvinylpyrrolidone, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, or copolymers thereof, but is not necessarily limited to these, and any binder used in the manufacture of a dry electrode film is acceptable. The dry binder may particularly include a fluorine-based binder. Fluorine-based binders are, for example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride-hexapropylene (PVDF-HFP) copolymer, or polyvinylidene fluoride (PVDF).

[0082] The content of the second binder (42) included in the positive active material layer (120) may be, for example, 0.5 wt% to 10 wt% or 1 wt% to 5 wt% with respect to the total weight of the positive active material layer (120). By including the second binder (42) in this range in the positive active material layer (120), the bonding strength between the positive active material layer (120) and the positive current collector (110) is improved, and the electrode having the second binder (42) can maintain a high energy density.

[0083] Referring to FIG. 1, an all-solid-state battery (10) according to an exemplary embodiment may include a solid electrolyte layer (300) disposed between a positive electrode (100) and a negative electrode (200). The solid electrolyte layer (300) according to an embodiment may include a third sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics. The third sulfide-based solid electrolyte included in the solid electrolyte layer (300) may be the same as or different from any one of the materials that may be included in the second sulfide-based solid electrolyte (22) included in the aforementioned positive electrode active material layer (120).

[0084] The third sulfide-based solid electrolyte can be manufactured by processing starting materials, such as Li2S and P2S5, by methods such as melt quenching or mechanical milling. Additionally, heat treatment may be performed after such processing. The third sulfide-based solid electrolyte may be amorphous, crystalline, or a mixture thereof. Furthermore, the third sulfide-based solid electrolyte may include sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the second sulfide-based solid electrolyte (22) materials described above, for example. For example, the third sulfide-based solid electrolyte may be a material containing Li2S-P2S5. When using a sulfide-based solid electrolyte material comprising Li2S-P2S5 to form a tertiary sulfide-based solid electrolyte, the molar ratio of Li2S and P2S5 is, for example, in the range of Li2S : P2S5 = 50 : 50 to 90 : 10.

[0085] Tertiary sulfide-based solid electrolytes are, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I xIt may be an argyrodite-type compound comprising one or more selected from (0≤x≤2). The third sulfide-based solid electrolyte may be an argyrodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I. The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. Since the argyrodite-type solid electrolyte has a density of 1.5 g / cc or higher, the internal resistance of the all-solid-state battery is reduced, and defects such as penetration and short circuit of the solid electrolyte film due to lithium dendrite formation can be prevented. The elastic modulus of the solid electrolyte is, for example, 15 GPa to 35 GPa.

[0086] The solid electrolyte layer (300) may further include a binder. The binder included in the solid electrolyte layer (300) is, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited thereto. The binder of the solid electrolyte layer (300) may be the same as or different from the second binder (42) included in the positive electrode active material layer (120), the first binder (41) included in the intermediate layer (400) to be described later, or the binder included in the negative electrode active material layer (220).

[0087] Referring to FIG. 1, an all-solid-state battery (10) according to an exemplary embodiment may include an interlayer (400) disposed between a positive electrode (100) and a solid electrolyte layer (300).

[0088] FIG. 3 is a schematic cross-sectional view showing an enlarged view of region C of FIG. 1. Referring to FIG. 3, an intermediate layer (400) according to one embodiment may include a compound (50) represented by the following chemical formula 1, a halide-based solid electrolyte (60), a first sulfide-based solid electrolyte (21), and a first binder (41).

[0089] [Chemical Formula 1]

[0090] Li a Fe 1-x M x PO4

[0091] (In the above chemical formula 1, 0.90 ≤ a ≤ 1.8, 0 ≤ x ≤ 0.7, M is Mn, Mg, Co, Ni, or a combination thereof).

[0092] A compound (50) represented by Formula 1 according to an exemplary embodiment may have an olivine crystal structure or a spinel crystal structure. Such a compound (50) represented by Formula 1 may have improved thermal stability and structural stability compared to an oxide-based material having a layered crystal structure. A compound (50) represented by Formula 1 having an olivine crystal structure inhibits the escape of oxygen, for example, even at high temperatures. Therefore, a compound (50) represented by Formula 1 having an olivine crystal structure can more effectively suppress thermal runaway and / or ignition caused by a short circuit, etc.

[0093] According to another embodiment, the compound (50) represented by Chemical Formula 1 may be represented by Chemical Formula 2, which contains manganese and has a spinel crystal structure.

[0094] [Chemical Formula 2]

[0095] Li a Fe 1-x Mn x PO4

[0096] (In the above chemical formula 2, 0.90 ≤ a ≤ 1.8, 0 ≤ x ≤ 0.7).

[0097] A compound (50) represented by the manganese-containing formula 2 having a spinel crystal structure can prevent overcurrent in an all-solid-state secondary battery by exhibiting high DC resistance when a short circuit occurs. As a result, thermal runaway of the all-solid-state battery can be prevented.

[0098] An intermediate layer (400) comprising a compound (50) represented by Chemical Formula 1 according to one embodiment can form a thin olivine layer on the positive active material layer (120). In this case, it serves to protect the surface of the positive active material layer (120), thereby reducing interfacial resistance, and the reduction in interfacial resistance can increase the storage capacity and recovery capacity when left at high temperatures.

[0099] The compound (50) represented by Chemical Formula 1 may include, for example, lithium transition metal oxide secondary particles. The lithium transition metal oxide secondary particles may include, for example, a plurality of lithium transition metal oxide primary particles and a carbon-based material. A plurality of lithium transition metal oxide primary particles and a carbon-based material may aggregate to form lithium transition metal oxide secondary particles. The particle size of the lithium transition metal oxide primary particles may be, for example, less than 1 μm, 500 nm or less, 300 nm or less, 200 nm or less, or 100 nm or less. The particle size of the lithium transition metal oxide primary particles may be, for example, 10 nm to 900 nm, 10 nm to 500 nm, 10 nm to 300 nm, 10 nm to 200 nm, or 10 nm to 100 nm. As the lithium transition metal oxide primary particles have a particle size within this range, the ionic conductivity and / or electronic conductivity of the lithium transition metal oxide secondary particles formed by the aggregation of the lithium transition metal oxide primary particles and carbon-based materials can be further enhanced. Consequently, the charge-discharge characteristics of the all-solid-state secondary battery can be further improved. The particle size of the lithium transition metal oxide secondary particles may be, for example, 10 μm or less, 5 μm or less, 3 μm or less, or 2 μm or less. The particle size of the lithium transition metal oxide secondary particles may be, for example, 0.5 to 10 μm, 0.5 to 5 μm, 0.5 to 3 μm, or 0.5 to 2 μm. As the lithium transition metal oxide secondary particles have a particle size within this range, the internal resistance of the anode (100), in which an intermediate layer (400) containing lithium transition metal oxide secondary particles is disposed on the surface of the anode active material layer (120), can be further reduced. Consequently, the charge / discharge characteristics of the all-solid-state battery (10) can be further improved.

[0100] The content of the compound (50) represented by Formula 1 included in the intermediate layer (400) according to one embodiment may be, for example, 80 wt% or more, 85 wt% or more, or 90 wt% or more of the total weight of the intermediate layer (400). The content of the compound (50) represented by Formula 1 included in the intermediate layer (400) may be, for example, 80 wt% to 99 wt%, 85 wt% to 99 wt%, 90 wt% to 99 wt%, 90 wt% to 97 wt%, or 90 wt% to 95 wt% of the total weight of the intermediate layer (400). By including the compound (50) represented by Formula 1 within this range in the intermediate layer (400), the all-solid-state battery (10) can simultaneously provide excellent thermal stability and excellent charge / discharge characteristics. If the content of the compound (50) represented by Chemical Formula 1 is excessively low, the heat blocking effect of the intermediate layer (400) may be reduced. If the content of the compound (50) represented by Chemical Formula 1 is excessively high, the interfacial resistance of the intermediate layer (400) may be excessively increased.

[0101] The thickness of the intermediate layer (400) according to one embodiment may be 1 μm to 13 μm. For example, the thickness of the intermediate layer (400) according to one embodiment may be 2 μm to 4 μm. If the thickness of the intermediate layer (400) falls within the above range, there may be an advantage of enhanced stability.

[0102] The thickness of the positive active material layer (130) according to one embodiment may be 60 μm to 70 μm. For example, the thickness of the positive active material layer (130) according to one embodiment may be 30 μm to 70 μm. When the thickness of the positive active material layer (130) falls within the above range, there may be an advantage of increased energy density due to thickening.

[0103] The ratio of the thickness of the intermediate layer (400) to the thickness of the positive active material layer (120) may be 30:1 to 10:1. Alternatively, the thickness of the intermediate layer (400) may be 20% or less of the thickness of the positive active material layer (120). When the ratio of the thickness of the intermediate layer (400) to the thickness of the positive active material layer (120) falls within the above range, there may be an advantage in obtaining an intermediate layer (400) that improves safety while minimizing the reduction in energy density. When the thickness of the intermediate layer (400) and the thickness of the positive active material layer (120) fall within the above range, and the ratio of the thickness of the intermediate layer (400) to the thickness of the positive active material layer (120) falls within the above range, there may be an advantage in that safety is enhanced by an appropriate thickness of the intermediate layer (400) according to the thickness of the positive active material layer (120).

[0104] Referring to FIG. 4, an intermediate layer (400) according to one embodiment may include a halide-based solid electrolyte (60). Referring to FIG. 4, the surface of a compound (50) represented by Formula 1 according to one embodiment may have a form coated by a halide-based solid electrolyte (60). A portion of the surface of a compound (50) represented by Formula 1 according to one embodiment may be coated by a halide-based solid electrolyte (60), and the entire surface of a compound (50) represented by Formula 1 according to another embodiment may be coated by a halide-based solid electrolyte (60). By including a compound (50) represented by Formula 1 coated by a halide-based solid electrolyte (60) in the intermediate layer (400), side reactions occurring at the interface between the positive active material layer (120) and the solid electrolyte layer (300) can be suppressed, and consequently, there may be an advantage of enhanced stability.

[0105] A halide-based solid electrolyte (60) according to one embodiment may include Li2ZrCl6, Li3YCl6, Li3InCl6, or a combination thereof.

[0106] Referring to FIG. 4, an intermediate layer (400) according to one embodiment may include a first sulfide-based solid electrolyte (21) having excellent lithium ion conductivity characteristics. The first sulfide-based solid electrolyte (21) included in the intermediate layer (400) may be the same as or different from any one of the materials that may be included in the second sulfide-based solid electrolyte (22) included in the aforementioned positive electrode active material layer (120) and / or the third sulfide-based solid electrolyte included in the aforementioned solid electrolyte layer (300). That is, the first sulfide-based solid electrolyte (21), the second sulfide-based solid electrolyte (22), and the third sulfide-based solid electrolyte are each independently of Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m, n are positive numbers, uppercase “Z” is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, uppercase “M” is one of P, Si, Ge, B, Al, Ga, In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I xIt may include at least one selected from (0≤x≤2). Alternatively, the first sulfide-based solid electrolyte (21), the second sulfide-based solid electrolyte (22) and the third sulfide-based solid electrolyte according to one embodiment may each independently include an azirodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0107] Referring to FIG. 4, an intermediate layer (400) according to one embodiment may include a first binder (41). The first binder (41) may be a binder having oxidation resistance at high voltage.

[0108] The first binder (41) may include, for example, styrene butadiene rubber (SBR), carboxymethylcellulose, polyacrylic acid, polymethyl methacrylate, polyisobutyl methacrylate, polyethyl acrylate, polybutyl acrylate, polyimide, polyamideimide, polyacrylonitrile, polyvinyl acetate, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, or a combination thereof. The content of the first binder (41) included in the intermediate layer (400) may be, for example, 0.1 wt% to 10 wt%, 0.5 to 5 wt%, or 0.5 to 2 wt% of the total weight of the intermediate layer (400).

[0109] A binder having oxidation resistance at such high voltage can not only reversibly intercalate and deintercalate the lithium of the positive active material layer (120), but also bond well with the compound of Formula 1 (50), thereby maintaining a strong bond between the intermediate layer (400) and the positive active material layer (120).

[0110] The mixing ratio of the compound (50) of Formula 1 and the first binder (41) may be 24:1 to 50:1 by weight, or 43:1 to 50:1 by weight. When the mixing ratio of the compound (50) of Formula 1 and the first binder (41) is within the above range, there may be advantages as an appropriate ratio in terms of energy density, adhesion, dispersibility, etc.

[0111] The intermediate layer (400) may further include a thickening agent. As the thickening agent, one or more types such as carboxymethyl cellulose, hydroxypropylmethylcellulose, methyl cellulose, or alkali metal salts thereof may be mixed and used. Na, K, or Li may be used as the alkali metal. When the intermediate layer (400) further includes a thickening agent, the content of the thickening agent may be 0.6 to 2 parts by weight per 100 parts by weight of the compound (50) of Formula 1. When the content of the thickening agent falls within this range, there may be advantages in improving thickening and dispersibility while minimizing the increase in resistance.

[0112] The intermediate layer (400) has a composition comprising the compound (50) of Formula 1 and the first binder (41), optionally a thickener, and may not include a conductive material. If a conductive material is included in the intermediate layer (400), safety is reduced due to the occurrence of a short circuit, etc., so it is not suitable.

[0113] Referring to FIG. 1, an all-solid-state battery (10) according to one embodiment may include a negative electrode layer (200). The negative electrode layer (200) may include a negative electrode current collector (210). In one embodiment, lithium metal and / or a lithium alloy may be deposited on the negative electrode current collector (210) by charging. In this case, the lithium metal and / or lithium alloy may act as a lithium reservoir. That is, the all-solid-state battery (10) according to one embodiment may be a lithium metal battery.

[0114] The negative current collector (210) may provide a reference surface on which the negative active material layer (220) or the negative coating layer (230) is disposed. The negative current collector (210) may include, for example, a material that does not react with lithium, that is, does not form any alloys or compounds with lithium. The material constituting the negative current collector (210) may include at least one metal selected from the group consisting of, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The thickness of the negative current collector may be 1 to 20 μm, for example 5 to 15 μm, for example 7 to 10 μm.

[0115] The negative current collector (210) may be composed of one of the metals described above, or may include an alloy of two or more metals or a coating material. The negative current collector (210) is, for example, in the form of a plate or foil. In another embodiment, the negative current collector (210) may be omitted.

[0116] Hereinafter, an embodiment in which a negative active material layer (220) is applied on a negative current collector (210) and an embodiment in which a negative coating layer (230) is applied on a negative current collector (210) will each be described with reference to the drawings illustrated in the present disclosure.

[0117] Referring to FIG. 5, an all-solid-state battery (10) according to another embodiment may include a negative electrode layer (200), and the negative electrode layer (200) may further include a negative electrode current collector (210) and a negative electrode active material layer (220) on the negative electrode current collector (210). The negative electrode active material layer (220) may include a negative electrode active material and may further include a negative electrode binder and / or a negative electrode conductive material.

[0118] For example, the negative electrode active material layer (220) may contain 90% to 99% by weight of negative electrode active material, 0.5% to 5% by weight of binder, and more than 0% by weight and less than 5% by weight of conductive material.

[0119] The negative electrode binder serves to adhere the negative electrode active material particles well to each other and also to adhere the negative electrode active material well to the current collector (210). As the negative electrode binder, a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof may be used. When an aqueous binder is applied as the negative electrode binder, its composition may be the same as or different from the first binder (41) described above. When a dry binder is applied as the negative electrode binder, its composition may be the same as or different from the second binder (42) described above.

[0120] Examples of the above-mentioned non-aqueous binders include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide imide, polyimide, or combinations thereof.

[0121] The above-mentioned water-based binder may be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylenepropylenediene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0122] When a water-based binder is used as the above-mentioned cathode binder, a cellulose-based compound capable of imparting viscosity may be further included. As this cellulose-based compound, one or more types such as carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or alkali metal salts thereof may be mixed and used. Na, K, or Li may be used as the alkali metal.

[0123] The above dry binder is a polymer material capable of fiberization, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a combination thereof.

[0124] The negative electrode conductive material is used to impart conductivity to the electrode, and any electronically conductive material that does not cause chemical changes can be used in the battery being constructed. Specific examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube; metal-based materials in the form of metal powder or metal fibers including copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0125] The negative electrode active material in the negative electrode active material layer (220) includes a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0126] A material capable of reversibly intercalating / deintercalating the above lithium ions may be a carbon-based negative electrode active material, such as crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flake-like, spherical, or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0127] As the above lithium metal alloy, an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn may be used.

[0128] As a material capable of doping and undoping the above lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material may be used. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiOx (0 ≤ x ≤ 2), a Si-Q alloy (wherein Q is selected from alkali metals, alkaline earth metals, group 13 elements, group 14 elements (excluding Si), group 15 elements, group 16 elements, transition metals, rare earth elements, and combinations thereof), or a combination thereof. The Sn-based negative electrode active material may be Sn, SnO2, a Sn-based alloy, or a combination thereof.

[0129] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, it may include a secondary particle (core) assembled from silicon primary particles and an amorphous carbon coating layer (shell) located on the surface of the secondary particle. The amorphous carbon may also be located between the silicon primary particles, so that, for example, the silicon primary particles may be coated with amorphous carbon. The secondary particles may be dispersed in an amorphous carbon matrix.

[0130] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer located on the surface of the core.

[0131] The above Si-based or Sn-based negative electrode active material can be used in combination with a carbon-based negative electrode active material.

[0132] Referring to FIG. 6, an all-solid-state battery (10) according to another embodiment may include a negative electrode layer (200), and the negative electrode layer (200) may further include a negative electrode current collector (210) and a negative electrode coating layer (230) on the negative electrode current collector (210). The negative electrode coating layer (230) may be configured to allow lithium metal to grow between the negative electrode current collector (210) and the negative electrode coating layer (230) and / or inside the negative electrode coating layer (230) when the all-solid-state battery (10) is charged. The negative electrode coating layer (230) may serve as a protective layer for the lithium metal and simultaneously suppress the precipitation and growth of lithium dendrites. The negative electrode coating layer (230) may include, for example, a metal-carbon composite and a binder.

[0133] The metal-carbon composite included in the cathode coating layer (230) is a cathode material capable of forming an alloy or compound with, for example, lithium. The metal-carbon composite has, for example, a particle form. The average particle size of the metal-carbon composite having a particle form is, for example, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, 500 nm or less, 300 nm or less, or 100 nm or less. The average particle size of the metal-carbon composite having a particle form is, for example, 10 nm to 4 μm, 10 nm to 3 μm, 10 nm to 2 μm, 10 nm to 1 μm, or 10 nm to 500 nm, 10 nm to 300 nm, or 10 nm to 100 nm. By having the average particle size of the metal-carbon composite within this range, reversible absorption and / or desorption of lithium during charging and discharging may be more facilitated. The average particle size of the metal-carbon composite is, for example, the median diameter (D50) measured using a laser particle size distribution meter.

[0134] A metal-carbon composite may include, for example, metal particles and a carbonaceous material. The metal particles and the carbonaceous material may each have a particle form, for example. A metal-carbon composite may be, for example, a simple mixture of metal particles and a carbonaceous material. The metal particles within the metal-carbon composite may include at least one metal or metalloid selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). However, this is not limited thereto, and any metal or metalloid used in the art to form an alloy or compound with lithium is acceptable. The carbonaceous material within the metal-carbon composite may include, for example, amorphous carbon, crystalline carbon, porous carbon, or a combination thereof. The carbonaceous material within the metal-carbon composite may be amorphous carbon. The carbonaceous material within the metal-carbon composite may include, for example, carbon black, acetylene black, furnace black, Kettjen black, graphene, or a combination thereof. Amorphous carbon may be carbon that does not have crystallinity or has very low crystallinity. The carbonaceous material within the metal-carbon composite may be, for example, porous carbon. The pore volume contained in the porous carbon may be, for example, 0.1 cc / g to 10.0 cc / g, 0.5 cc / g to 5 cc / g, or 0.1 cc / g to 1 cc / g. The average pore diameter contained in the porous carbon may be, for example, 1 nm to 50 nm, 1 nm to 30 nm, or 1 nm to 10 nm. The BET specific surface area of ​​the porous carbon is, for example, 100 m² 2 / g to 3,000 m 2It can be / g. The BET specific surface area of ​​porous carbon can be measured, for example, according to ISO 9277:2022.

[0135] The mixing ratio of the metal particles and carbon-based material included in the cathode coating layer (230) can be, for example, 1:10 to 2:1, 1:5 to 1:1, or 1:4 to 1:2 by weight.

[0136] The metal-carbon composite may be, for example, a composite of metal particles and a carbon-based material. The carbon-based material may be, for example, a carbon-based support. The metal-carbon composite may include, for example, a carbon-based support and metal particles supported on the carbon-based support. By having such a structure, the localization of metal particles within the cathode coating layer (230) is prevented and a uniform distribution can be obtained. Consequently, the cycle characteristics of the all-solid-state battery (10) including the cathode coating layer (230) can be further improved.

[0137] Metal particles supported on a carbon-based support may include, for example, a metal, a metal oxide, a composite of a metal and a metal oxide, or a combination thereof. The metal may include, for example, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), tellurium (Te), and zinc (Zn). The metal oxide may include, for example, gold (Au) oxide, platinum (Pt) oxide, palladium (Pd) oxide, silicon (Si) oxide, silver (Ag) oxide, aluminum (Al) oxide, bismuth (Bi) oxide, tin (Sn) oxide, tellurium (Te) oxide, and zinc (Zn) oxide. The metal oxide may include, for example, Au x O y (0 <x≤2, 0<y≤3), Pt x O y (0 <x≤1, 0<y≤2), Pd x O y (0 <x≤1, 0<y≤1), Si xThe y (0 <x≤1, 0<y≤2), Ag x The y (0 <x≤2, 0<y≤1), Al x The y (0 <x≤2, 0<y≤3), Bi x The y (0 <x≤2, 0<y≤3), Sn x The y (0 <x≤1, 0<y≤2), Te x The y (0 <x≤1,0<y≤3), Zn x The y (0 <x≤1, 0<y≤1) 또는 이들의 조합을 포함할 수 있다. 금속과 금속 산화물의 복합체는 예를 들어 Au와 Au x The y (0 <x≤2, 0<y≤3)의 복합체, Pt와 Pt x The y (0 <x≤1, 0<y≤2)의 복합체, Pd와 Pd x The y (0 <x≤1, 0<y≤1)의 복합체, Si와 Si x The y (0 <x≤1, 0<y≤2)의 복합체, Ag 와 Ag x The y (0 <x≤2, 0<y≤1)의 복합체, Al과 Al x The y (0 <x≤2, 0<y≤3)의 복합체, Bi와 Bi x The y (0 <x≤2, 0<y≤3)의 복합체, Sn과 Sn x The y (0 <x≤1, 0<y≤2)의 복합체, Te과 Te x The y (0 <x≤1, 0<y≤3), Zn과 Zn x The y (0 <x≤1, 0<y≤1)의 복합체, 또는 이들의 조합을 포함할 수 있다.

[0138] A carbon-based support is, for example, amorphous carbon. Amorphous carbon is, for example, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), graphene, activated carbon, carbon nanofiber (CNF), carbon nanotube (CNT), etc., but is not necessarily limited to these, and any carbon classified as amorphous carbon in the relevant technical field is acceptable. Amorphous carbon is carbon that does not have crystallinity or has very low crystallinity, and is distinguished from crystalline carbon or graphite-based carbon.

[0139] The binder included in the cathode coating layer (230) may be, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc., but is not necessarily limited to these and any binder used in the relevant technical field is possible. The binder may be composed of a single binder or a plurality of different binders.

[0140] The cathode coating layer (230) is stabilized on the cathode current collector (210) by including a binder. Additionally, cracking of the cathode coating layer (230) is suppressed despite volume changes and / or relative position changes of the cathode coating layer (230) during the charging and discharging process. For example, if the cathode coating layer (230) does not include a binder, it is possible for the cathode coating layer (230) to be easily separated from the cathode current collector (210). As the cathode coating layer (230) detaches from the cathode current collector (210), the possibility of a short circuit occurring increases in the portion of the cathode current collector (210) exposed by the cathode current collector (210) coming into contact with the solid electrolyte layer (300). The cathode coating layer (230) is produced, for example, by applying a slurry in which the material constituting the cathode coating layer (230) is dispersed onto a cathode current collector (210) and drying it. By including a binder in the cathode coating layer (230), stable dispersion of the metal-carbon composite in the slurry is possible. For example, when the slurry is applied onto the cathode current collector (210) by a screen printing method, it is possible to suppress clogging of the screen.

[0141] The cathode coating layer (230) may further include other additives in addition to the metal-carbon composite. The cathode coating layer (230) may further include at least one additive selected from the group consisting of, for example, fillers, coating agents, dispersants, and ion-conducting aids.

[0142] The cathode coating layer (230) may further include a solid electrolyte. The solid electrolyte may be a material selected from, for example, the solid electrolyte included in the solid electrolyte layer (300). The solid electrolyte included in the cathode coating layer (230) may act as a reaction site where the formation of lithium metal begins within the cathode coating layer (230), act as a space where the formed lithium metal is stored, or act as a path for transporting lithium ions. The solid electrolyte may be omitted.

[0143] Referring to FIG. 7, an all-solid-state battery (10) according to another embodiment includes a negative electrode layer (200), the negative electrode layer (200) includes a negative electrode current collector (210) and a negative electrode coating layer (230) on the negative electrode current collector (210), and may further include a lithium metal layer (240) disposed between the negative electrode current collector (210) and the negative electrode coating layer (230). The lithium metal layer (240) may be a configuration formed by charging the all-solid-state battery (10). Although not shown in the drawing, the all-solid-state battery (10) may further include a lithium metal layer (240) disposed inside the negative electrode coating layer (230) by charging.

[0144] The lithium metal layer (240) may include lithium or a lithium alloy. Since the lithium metal layer (240) is a metal layer containing lithium, it may function as, for example, a lithium reservoir. The lithium alloy may be, for example, Li-Al alloy, Li-Sn alloy, Li-In alloy, Li-Ag alloy, Li-Au alloy, Li-Zn alloy, Li-Ge alloy, Li-Si alloy, etc., but is not limited to these; any alloy used as a lithium alloy in the relevant technical field may be possible. The lithium metal layer (240) may be composed of one of these alloys or lithium, or may be composed of various types of alloys. The lithium metal layer (240) may be, for example, a plated layer. The lithium metal layer (240) may be, for example, deposited between the negative electrode coating layer (230) and the negative electrode current collector (210) during the charging process of the all-solid-state battery (10).

[0145] In another embodiment, the lithium metal layer (240) within the negative electrode layer (200) may be provided, for example, between the negative electrode current collector (210) and the negative electrode coating layer (230) before assembly of the all-solid-state battery (10). When the lithium metal layer (240) is placed between the negative electrode current collector (210) and the negative electrode coating layer (230) before assembly of the all-solid-state battery (10), the lithium metal layer (240) acts as a lithium reservoir because it is a metal layer containing lithium. For example, a lithium foil may be placed between the negative electrode current collector (210) and the negative electrode coating layer (230) before assembly of the all-solid-state battery (10).

[0146] When a lithium metal layer (240) is deposited by charging after assembly of the all-solid-state battery (10), the energy density of the all-solid-state battery (10) can be increased because the lithium metal layer (240) is not included during assembly of the all-solid-state battery (10). When charging the all-solid-state battery (10), it can be charged beyond the charging capacity of the negative electrode coating layer (230). That is, the negative electrode coating layer (230) is overcharged. At the beginning of charging, lithium can be absorbed in the negative electrode coating layer (230). When charging beyond the capacity of the negative electrode coating layer (230), lithium can be deposited, for example, between the negative electrode coating layer (230) and the negative electrode current collector (210). A lithium metal layer (240) can be formed by the deposited lithium.

[0147] The lithium metal layer (240) can be composed mainly of lithium (i.e., metallic lithium). During discharge, the lithium in the lithium metal layer (240) can be ionized and move to the positive electrode (100). In other words, lithium can be used as a negative electrode active material in the all-solid-state battery (10). In addition, since the negative electrode coating layer (230) covers the lithium metal layer (240), the negative electrode coating layer (230) can protect the lithium metal layer (240) and simultaneously suppress the precipitation growth of lithium dendrites. Therefore, the negative electrode coating layer (230) can suppress short circuits and capacity degradation of the all-solid-state battery (10) and improve the cycle characteristics of the all-solid-state battery (10).

[0148] When a lithium metal layer (240) is formed by charging after assembly of the all-solid-state battery (10), the negative electrode layer (200), that is, the negative electrode current collector (210) and the negative electrode coating layer (230) and the region between them may be a Li-free region that does not contain lithium (Li) in the initial state or after complete discharge of the all-solid-state battery (10).

[0149]

[0150] The creative idea is explained in more detail through the following examples and comparative examples. However, the examples are intended to illustrate the creative idea and do not limit the scope of the creative idea to these examples alone.

[0151] Example 1

[0152] (Manufacturing of cathode active material)

[0153] Li2S, LiI, and AlI3 were mixed in a weight ratio of 40:5:15. The mixture was mechanically milled using a ball mill to prepare a Li2S-LiI-AlI3 composite. The milling conditions were 25 ℃ and 450 rpm for 10 hours. The milling energy applied to the sample during milling was 20 G. The Li2S-LiI-AlI3 composite thus prepared was mixed with carbon nanofiber (CNF) in a weight ratio of 60:10. The mixture was mechanically milled using a ball mill to prepare a Li2S-LiI-AlI3-CNF composite. The milling conditions were 25 ℃ and 450 rpm for 10 hours. The milling energy applied to the sample during milling was 20 G. The Li2S-LiI-AlI3-CNF composite thus prepared was used as the cathode active material.

[0154] (Manufacturing of the anode)

[0155] Li6PS5Cl (D50 = 1.0 μm, crystalline), an argyrodite-type crystal, was prepared as the solid electrolyte. PTFE was prepared as the binder. The prepared cathode active material, solid electrolyte, and binder were mixed in a weight ratio of cathode active material : solid electrolyte : binder = 70 : 29 : 1 to prepare a cathode composite. The cathode composite was obtained by dry mixing using a mixer.

[0156] An anode was manufactured by placing the anode mixture on one side of an anode current collector made of aluminum foil with carbon coating on one side and plate pressing it for 10 minutes at a pressure of 200 MPa.

[0157] (Manufacturing of the middle layer)

[0158] A slurry was prepared by mixing LiFePO4 (D50 = 1 μm), Li6PS5Cl (D50 = 0.5 μm, crystalline), which is an argyrodite-type crystal as a first sulfide-based solid electrolyte, and an acrylic binder in a weight ratio of 90:5:5, while adding octyl acetate and stirring.

[0159] A bar coating of the slurry was applied onto the positive active material layer of the prepared laminate, dried at room temperature, and then dried again under vacuum conditions at 120°C to introduce an intermediate layer onto the positive active material layer.

[0160] The thickness of the anode was approximately 120 µm. The thickness of the anode active material layer was approximately 100 µm, the thickness of the intermediate layer was approximately 3 µm, the thickness of the carbon layer was approximately 2 µm, and the thickness of the aluminum foil was approximately 15 µm.

[0161] (Manufacturing of the cathode layer)

[0162] A SUS foil with a thickness of 10 μm was prepared as a cathode current collector. As a metal-carbon composite, carbon black (CB) with a primary particle size of about 30 nm and silver (Ag) particles with an average particle diameter of about 60 nm were prepared.

[0163] 4 g of a mixed powder, prepared by mixing carbon black (CB) and silver (Ag) particles in a weight ratio of 3:1, was placed in a container, and 4 g of an NMP solution containing 7 wt% of a PVDF binder (Kureha # 9300) was added to prepare a mixed solution. A slurry was prepared by stirring the mixed solution while gradually adding NMP to it. The prepared slurry was applied to a SUS sheet using a bar coater, dried in air at 80°C for 10 minutes, and then vacuum dried at 40°C for 10 hours to prepare a laminate. The prepared laminate was cold-roll-pressed to flatten the surface, thereby preparing a cathode having a cathode coating layer / cathode current collector structure. The thickness of the cathode coating layer was approximately 15 μm. The surface area of ​​the cathode coating layer and the cathode current collector were the same.

[0164] (Preparation of solid electrolyte layer)

[0165] A mixture was prepared by adding 1.5 parts by weight of an acrylic binder to 98.5 parts by weight of a solid electrolyte, which is an argyrodite-type crystal Li6PS5Cl. A slurry was prepared by stirring while adding octyl acetate to the prepared mixture. The prepared slurry was applied using a bar coater onto a 15 μm thick nonwoven fabric placed on a 75 μm thick PET substrate, and a laminate was prepared by drying in air at 80°C for 10 minutes. A solid electrolyte layer was prepared by vacuum drying the prepared laminate at 80°C for 2 hours.

[0166] Manufacturing of all-solid-state batteries

[0167] The fabricated cathode layer, the solid electrolyte layer on the cathode layer, and the anode on the solid electrolyte layer were sequentially arranged. The prepared laminate was subjected to plate pressing at 85 °C under a pressure of 500 MPa for 30 minutes. This pressurization process sintered the solid electrolyte layer, thereby improving battery characteristics. The thickness of the sintered solid electrolyte layer was approximately 45 μm. The density of the Li6PS5Cl solid electrolyte, an argyrodite-type crystal contained in the sintered solid electrolyte layer, was 1.6 g / cc. The area of ​​the solid electrolyte layer was equal to the area of ​​the cathode layer.

[0168] An all-solid-state battery was manufactured by placing a pressurized laminate into a pouch and vacuum sealing it. Parts of the positive and negative current collectors were extended outside the sealed battery to serve as the positive and negative terminals.

[0169] Example 2

[0170] An all-solid-state battery was manufactured using the same method as in Example 1, except that the intermediate layer was manufactured as follows.

[0171] (Manufacturing of the middle layer)

[0172] A halide-based solid electrolyte was prepared by weighing LiCl and ZrCl4 as precursors in a 2:1 molar ratio. Li2ZrCl6 was synthesized by mechanically mixing the prepared LiCl and ZrCl4.

[0173] The synthesized Li2ZrCl6 was mixed with LiFePO4 (D50 = 1 μm), and then ball milled to coat the surface of LiFePO4 with Li2ZrCl6.

[0174] A slurry was prepared by adding octyl acetate to a mixture of LiFePO4 (D50 = 1 μm) coated with Li2ZrCl6 on the surface, Li6PS5Cl (D50 = 0.5 μm, crystalline), which is an argyrodite-type crystal as a first sulfide-based solid electrolyte, and an acrylic binder in a weight ratio of 90:5:5 and stirring.

[0175] A bar coating of the slurry was applied onto the positive active material layer of the prepared laminate, dried at room temperature, and then dried again under vacuum conditions at 120°C to introduce an intermediate layer onto the positive active material layer.

[0176] The thickness of the anode was approximately 120 µm. The thickness of the anode active material layer was approximately 100 µm, the thickness of the intermediate layer was approximately 3 µm, the thickness of the carbon layer was approximately 2 µm, and the thickness of the aluminum foil was approximately 15 µm.

[0177] In the final intermediate layer, LiFePO4 coated with Li2ZrCl6 and Li6PS5Cl were mixed.

[0178] Comparative Example 1

[0179] An all-solid-state battery was manufactured in the same manner as in Example 1, except that an intermediate layer was not introduced.

[0180] The anode had an anode active material layer / carbon layer / aluminum foil structure. The thickness of the anode active material layer was approximately 100 µm. The anode thickness was approximately 117 µm.

[0181] Evaluation Example 1: Charge / Discharge Test

[0182] The charge-discharge characteristics of the all-solid-state batteries prepared in Examples 1 and 2 and Comparative Example 1 were evaluated by the following charge-discharge test. The charge-discharge test was performed by placing the all-solid-state batteries in a constant temperature bath at 45°C.

[0183] The first cycle involved charging at a constant current of 0.05 C for 20 hours until the battery voltage reached 2.8 V. Subsequently, discharging was performed at a constant current of 0.05 C for 20 hours until the battery voltage reached 1.0 V.

[0184] The discharge capacity of the first cycle was set as the standard capacity. The standard capacity is expressed as the specific capacity of the positive active material in Table 1 below.

[0185] Charge and discharge tests were conducted twice using the method above (formation cycles),

[0186] After the third cycle, charging and discharging were performed for up to 300 cycles with a constant current of 0.1C. Some of the evaluation results are shown in Table 1 below.

[0187] The number of cycles refers to the number of cycles required for the discharge capacity to decrease to 80% of the standard capacity after the third cycle. It was considered that the life characteristics were superior as the number of cycles increased.

[0188] The initial efficiency is expressed by the following mathematical formula 1.

[0189] <Mathematical Formula 1>

[0190] Initial Efficiency [%] = [1st Cycle Discharge Capacity / 1st Cycle Charge Capacity] × 100 [%]

[0191] Evaluation Example 2: Rate Characteristic Evaluation

[0192] The high-rate characteristics of the all-solid-state batteries of Examples 1 and 2 and Comparative Example 1 were evaluated by the following charge-discharge test. The charge-discharge test was performed by placing the all-solid-state batteries in a constant temperature bath at 45°C.

[0193] The all-solid-state batteries of Examples 1 and 2 and Comparative Example 1 were charged at a constant current rate of 0.05 C at 45 ℃ until the voltage reached 2.8 V (vs. Li), and discharged at a constant current rate of 0.05 C until the voltage reached 1 V (vs. Li) (1st and 2nd cycles (formation cycles)).

[0194] The all-solid-state battery that had undergone the formation cycle was charged at a constant current rate of 0.1 C at 45 ℃ until the voltage reached 2.8 V (vs. Li). Subsequently, it was discharged at a constant current rate of 0.1 C until the voltage reached 1 V (vs. Li) during discharge (3rd cycle).

[0195] A 10-minute pause was observed after each charge / discharge cycle in all charge / discharge cycles. Some of the evaluation results are shown in Table 1 below. The high-rate characteristic is defined by the following Equation 2.

[0196] <Mathematical Formula 2>

[0197] High Rate Characteristic [%] = [Discharge capacity at 3rd cycle (0.1C) / Discharge capacity at formation cycle (2nd cycle) (0.05C)] × 100

[0198] Initial Efficiency [%] Specific Capacity [mAh / g] Number of Cycles [turns] High Rate Characteristics [%] Example 1 Intermediate Layer (LiFePO4+Li6PS5Cl) / Cathode Active Material Layer / Al 8 1.280211082.5 Example 2 Intermediate Layer (LiFePO4+Li2ZrCl6+Li6PS5Cl) / Cathode Active Material Layer / Al 8 3.585514084.1 Comparative Example 1 Cathode Active Material Layer / Al 7 2.67091580.5

[0199] As shown in Table 1, the all-solid-state batteries of Examples 1 and 2 exhibited improved charge-discharge characteristics compared to the all-solid-state battery of Comparative Example 1. The charge-discharge characteristics of the all-solid-state batteries of Examples 1 and 2 were improved by introducing an intermediate layer, which increased the adhesion between the positive active material layer and the electrolyte layer and reduced the interfacial resistance.

[0200] Evaluation Example 3: Thermal Stability Evaluation

[0201] Penetration tests were performed on the all-solid-state batteries prepared in Examples 1 and 2 and Comparative Example 1.

[0202] The penetration test was conducted by charging the all-solid-state battery to 2.5 V at 0.5 C for 2 hours, stopping it for about 10 minutes, and then using a pin with a diameter of 5 mm to completely penetrate the center of the all-solid-state battery at a speed of 60 mm / sec. Based on whether ignition occurred after penetration, all-solid-state batteries that did not ignite were judged as ○, and those that ignited were judged as ×. Some of the evaluation results are shown in Table 2 below.

[0203] The maximum temperature of the heat generation was measured by measuring the temperature change of the all-solid-state secondary battery for 48 hours after penetration.

[0204] Thermal Stability Example 1 Intermediate layer (LiFePO4 + Li6PS5Cl) / Cathode active material layer / Al○ Example 2 Intermediate layer (LiFePO4 + Li2ZrCl6 + Li6PS5Cl) / Cathode active material layer / Al○ Comparative Example 1 Cathode active material layer / Al×

[0205] As shown in Table 2, the thermal stability of the all-solid-state batteries of Examples 1 and 2 was improved compared to the all-solid-state battery of Comparative Example 1. The thermal stability of the all-solid-state batteries of Examples 1 and 2 was improved by the introduction of an intermediate layer.

[0206] Although not shown in Table 2, the relative heights of the peak exothermic temperatures of the all-solid-state batteries of Examples 1 and 2 and Comparative Example 1 were as follows: Comparative Example 1 > Example 1 > Example 2

[0207] Although an exemplary embodiment has been described in detail above with reference to the attached drawings, the present creative idea is not limited to such examples. It is obvious that a person skilled in the art to which the present creative idea belongs can derive various variations or modifications within the scope of the technical idea described in the patent claims, and these also naturally fall within the technical scope of the present creative idea.

Claims

1. A positive electrode comprising a positive active material; a negative electrode; a solid electrolyte layer disposed between the positive electrode and the negative electrode; and an interlayer disposed between the positive electrode and the solid electrolyte layer, wherein The above-mentioned positive active material comprises a composite of a sulfur-based material, a metal halide salt, and a carbon-based material, and The above sulfur-based materials are S8 and Li2S n Includes at least one of (1 ≤ n ≤ 8, n is an integer), and The above metal halide salt comprises a first metal halide salt comprising an alkali metal and a second metal halide salt comprising a boron group metal, and All-solid-state battery, wherein the above intermediate layer comprises a compound represented by the following chemical formula 1 and a first sulfide-based solid electrolyte: [Chemical Formula 1] Li a Fe 1-x M x PO4 (In the above chemical formula 1, 0.90 ≤ a ≤ 1.8, 0 ≤ x ≤ 0.7, M is Mn, Mg, Co, Ni, or a combination thereof).

2. In Paragraph 1, The above-mentioned first metal halide salt comprises LiF, LiCl, LiBr, LiI, or a combination thereof, in an all-solid-state battery.

3. In Paragraph 1, The above-mentioned second metal halide salt comprises AlF3, AlCl3, AlBr3, AlI3, GaF3, GaCl3, GaBr3, GaI3, InF3, InCl3, lnBr3, lnI3, TiF3, TiCl3, TiBr3, TiI3, or a combination thereof, in an all-solid-state battery.

4. In Paragraph 1, An all-solid-state battery having a content of the sulfur-based material of 20 to 80 weight percent based on the total weight of the composite.

5. In Paragraph 1, An all-solid-state battery having a content of the metal halide salt of 10 to 60 weight percent based on the total weight of the composite.

6. In Paragraph 5, The content of the first metal halide salt is 2.5 to 15 weight% with respect to the total weight of the composite, and An all-solid-state battery having a content of the second metal halide salt of 7.5 to 45 weight percent based on the total weight of the composite.

7. In Paragraph 1, An all-solid-state battery having a content of the carbon-based material of 1 to 30 weight percent based on the total weight of the composite.

8. In Paragraph 1, An all-solid-state battery in which the content of the compound represented by Chemical Formula 1 is 80 wt% or more of the total weight of the intermediate layer.

9. In Paragraph 1, The above intermediate layer comprises a halide-based solid electrolyte, in an all-solid-state battery.

10. In Paragraph 9, An all-solid-state battery in which the surface of the compound represented by the above chemical formula 1 is coated with the above halide-based solid electrolyte.

11. In Paragraph 9, The above-mentioned halide-based solid electrolyte comprises Li2ZrCl6, Li3YCl6, Li3InCl6, or a combination thereof, in an all-solid-state battery.

12. In Paragraph 1, The above anode comprises a second sulfide-based solid electrolyte, and The above solid electrolyte layer comprises a third sulfide-based solid electrolyte, in an all-solid-state battery.

13. In Paragraph 12, The first sulfide-based solid electrolyte, the second sulfide-based solid electrolyte, and the third sulfide-based solid electrolyte are each independently Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m, n are positive numbers, uppercase "Z" is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, uppercase "M" is one of P, Si, Ge, B, Al, Ga, In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x A solid-state battery comprising at least one selected from (0≤x≤2).

14. In Paragraph 12, An all-solid-state battery in which the first sulfide-based solid electrolyte, the second sulfide-based solid electrolyte, and the third sulfide-based solid electrolyte each independently comprise an azirodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

15. In Paragraph 1, The above positive electrode comprises a positive current collector and a positive active material layer on the positive current collector, and All-solid-state battery in which the thickness of the intermediate layer is 20% or less of the thickness of the positive active material layer.

16. In Paragraph 1, The above intermediate layer further comprises a first binder, and The above-mentioned first binder comprises styrene butadiene rubber (SBR), carboxymethylcellulose, polyacrylic acid, polymethyl methacrylate, polyisobutyl methacrylate, polyethyl acrylate, polybutyl acrylate, polyimide, polyamideimide, polyacrylonitrile, polyvinyl acetate, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, or a combination thereof, in an all-solid-state battery.

17. In Paragraph 1, The above positive electrode comprises a positive current collector and a positive active material layer on the positive current collector, and The above positive active material layer further comprises a second binder, and The second binder above is polytetrafluoroethylene (PTFE), polyamide-imide (PAI), polyimide (PI), styrene-butadiene rubber (SBR), (meth)acrylated styrene-butadiene rubber, polyethylene oxide (PEO), polyphosphazene, poly(meth)acrylonitrile (PAN), (meth)acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol (PVA), polyvinylidene fluoride (PVDF), and polyvinylidene All-solid-state battery comprising a polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) or a combination thereof.

18. In Paragraph 1, The above cathode further comprises a cathode current collector and a cathode active material layer on the cathode current collector, and The above-mentioned negative electrode active material layer comprises a carbon-based negative electrode active material, a Si-based negative electrode active material, a Sn-based negative electrode active material, or a combination thereof, in an all-solid-state battery.

19. In Paragraph 1, The above cathode further comprises a cathode current collector and a cathode coating layer on the cathode current collector, and The above-mentioned cathode coating layer comprises a metal-carbon composite, in an all-solid-state battery.

20. In Paragraph 19, The above cathode further includes a lithium metal layer disposed between the cathode current collector and the cathode coating layer, and The above lithium metal layer comprises lithium or a lithium alloy, and The above lithium alloy comprises a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy, or a combination thereof, in an all-solid-state battery.

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