All-solid-state secondary battery

Abstract

Provided is an all-solid-state secondary battery, comprising: a positive electrode layer; a negative electrode layer; a solid electrolyte layer between the positive electrode layer and the negative electrode layer; and a solid separator disposed at least one of between the positive electrode layer and the solid electrolyte layer and between the negative electrode layer and the solid electrolyte layer, wherein the negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer on one side of the negative electrode current collector, the solid electrolyte layer includes a sulfide-based solid electrolyte and an inorganic filler, and the inorganic filler includes lithium metal oxyhalide represented by chemical formula 1. The solid separator may include an inorganic filler or may include an inorganic filler and a sulfide-based solid electrolyte. <Chemical formula 1> LiaMbOcCld In chemical formula 1, 0<a≤3; 0<b≤3; 0<c≤3; 0<d≤8; c<d; a / (a+b+c+d)<0.5, and M is a metal selected from Groups 3-15 of the Periodic Table of Elements.

Description

All-solid-state secondary batteries

[0001] It's about all-solid-state secondary batteries.

[0002] Recent industrial demands have led to the active development of batteries with high energy density and safety. For example, lithium batteries are used in a variety of applications, including information technology, communications devices, and automobiles. Because automobiles are life-threatening, safety is also crucial.

[0003] Lithium batteries using liquid electrolytes may have an increased risk of fire and / or explosion in the event of a short circuit. All-solid-state secondary batteries using solid electrolytes instead of liquid electrolytes are being proposed. Solid electrolytes are less likely to catch fire than liquid electrolytes.

[0004] All-solid-state secondary batteries can reduce the risk of fire or explosion by using solid electrolytes instead of liquid electrolytes. All-solid-state secondary batteries can offer improved safety.

[0005] One aspect is to provide an all-solid-state secondary battery with improved charge-discharge characteristics by having a new solid electrolyte layer.

[0006] According to one embodiment, an all-solid-state secondary battery is provided, comprising: a cathode layer; a cathode layer; a solid electrolyte layer between the cathode layer and the cathode layer; and a solid separator disposed at least between the cathode layer and the solid electrolyte layer and between the cathode layer and the solid electrolyte layer, wherein the cathode layer includes a cathode current collector and a first cathode active material layer on one surface of the cathode current collector, the solid electrolyte layer includes a sulfide-based solid electrolyte and an inorganic filler, the solid separator includes a porous membrane and an inorganic filler, and the inorganic filler includes a lithium metal oxyhalide represented by the following chemical formula 1.

[0007] <Chemical Formula 1>

[0008] Li a M b O c Cl d

[0009] In chemical formula 1, 0 <a≤3; 0<b≤3; 0<c≤3; 0<d≤8; c<d; a / (a+b+c+d)<0.5, M은 원소주기율표 3족 내지 15족에서 선택되는 금속이다.

[0010] The content of the inorganic filler in the above solid electrolyte layer is 1 to 15 parts by weight based on 100 parts by weight of the solid electrolyte layer. In addition, the inorganic filler may be arranged within the pores of the sulfide-based solid electrolyte in the above solid electrolyte layer.

[0011] The above solid electrolyte layer includes a first solid electrolyte layer including a sulfide-based solid electrolyte and an inorganic filler, and a second solid electrolyte layer including a sulfide-based solid electrolyte and an inorganic filler, wherein the first solid electrolyte layer is arranged to be in contact with the negative electrode, the second solid electrolyte layer is arranged to be in contact with the positive electrode, and the content of the inorganic filler in the first solid electrolyte layer is smaller than the content of the inorganic filler in the first solid electrolyte layer.

[0012] The above solid separation membrane may further include a sulfide-based solid electrolyte.

[0013] The inorganic filler or the inorganic filler and the sulfide-based solid electrolyte are provided within the pores of the solid separation membrane, and the shape of the inorganic filler conforms to the shape of the pores, and the surface profile of the inorganic filler can conform to the surface profile of the pores.

[0014] According to one aspect, an all-solid-state secondary battery having improved safety and charge-discharge characteristics can be provided by having a solid electrolyte layer and a solid separator capable of preventing short-circuiting at high temperatures and accommodating volume changes during charge-discharge.

[0015] Figures 1 to 12 are cross-sectional views of all-solid-state secondary batteries according to exemplary embodiments, respectively.

[0016] [Explanation of symbols]

[0017] 1 All-solid-state secondary battery 10 Cathode

[0018] 11. Cathode current collector 12. Cathode active material layer

[0019] 13 Middle layer 20 Cathode

[0020] 21 Negative current collector 22 First negative electrode active material layer

[0021] 23 Thin film 24 Second negative electrode active material layer

[0022] 30 Electrolyte layer 40, 40a, 40b: Solid membrane

[0023] 50 inert elements

[0024] Unless otherwise defined, all terms (including technical and scientific terms) used in this disclosure have the same meaning as commonly understood by those of ordinary skill in the art to which this disclosure pertains. Furthermore, terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning within the context of the relevant technology and this disclosure, and should not be interpreted in an idealized or overly formal sense.

[0025] Exemplary embodiments are described in this disclosure with reference to cross-sectional drawings that are schematic representations of idealized embodiments. As such, variations from the shapes depicted are to be expected, for example, as a result of manufacturing techniques and / or tolerances. Therefore, the embodiments described in this disclosure should not be construed as limited to the specific shapes of regions as depicted in this disclosure, but should encompass variations in shapes resulting from, for example, manufacturing. For example, regions depicted or described as flat may typically have rough and / or non-linear features. Moreover, angles depicted as sharp may be rounded. Therefore, the regions depicted in the drawings are schematic in nature, and their shapes are not intended to depict the precise shapes of the regions, nor are they intended to limit the scope of the claims.

[0026] This creative idea may be embodied in many different forms and should not be construed as limited to the embodiments described in this disclosure. These embodiments are provided so that this disclosure will be thorough and complete, and so that it will fully convey the scope of the creative idea to those skilled in the art. Like reference numerals in the drawings indicate like elements.

[0027] When a component is referred to as being "on" another component, it can be understood that it is either directly on top of the other component or that other components may be intervening between them. Conversely, when a component is referred to as being "directly on" another component, no intervening components are present.

[0028] Although terms such as "first," "second," "third," etc. may be used herein to describe various components, elements, regions, layers, and / or zones, these components, elements, regions, layers, and / or zones should not be limited by these terms. These terms are only used to distinguish one component, element, region, layer, or zone from another component, element, region, layer, or zone. Thus, a first component, element, region, layer, or zone described below may be referred to as a second component, element, region, layer, or zone without departing from the teachings of this disclosure.

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms including "at least one," unless the content clearly dictates otherwise. "At least one" should not be construed as limiting to the singular. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items. The terms "comprises" and / or "comprising" as used in the detailed description specify the presence of stated features, regions, integers, steps, operations, components, and / or ingredients, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, components, ingredients, and / or groups thereof.

[0030] Spatially relative terms such as "below," "under," "lower," "above," "upper," and the like may be used herein to readily describe the relationship of one component or feature to another. It will be understood that spatially relative terms are intended to encompass different orientations of the device when in use or operation in addition to the orientations depicted in the drawings. For example, if the device in the drawings were turned over, a component described as "below" or "below" another component or feature would then be oriented "above" the other component or feature. Thus, the exemplary term "below" can encompass both the above and below orientations. The device may be arranged in other orientations (rotated 90 degrees or otherwise rotated), and the spatially relative terms used herein may be interpreted accordingly.

[0031] "Group" means a group in the periodic table of elements according to the International Union of Pure and Applied Chemistry ("IUPAC") Group 1-18 classification system.

[0032] In the present disclosure, “particle diameter” refers to the average diameter when the particles are spherical, and refers to the average major axis length when the particles are non-spherical. The particle diameter can be measured using a particle size analyzer (PSA). The average particle diameter and average major axis length of the particles can be measured using a scanning electron microscope. When measuring the particle size using a scanning electron microscope, it is determined as the average value of 30 or more randomly selected particles of 1 μm or more, excluding fine particles.

[0033] “Particle size” is, for example, the average particle size. “Average particle size” is, for example, the median particle diameter, D50. D50 is the size of the particle corresponding to 50% of the cumulative volume, calculated from the side of the particle having a small particle size in the size distribution of particles measured by laser diffraction. D90 is the size of the particle corresponding to 90% of the cumulative volume, calculated from the side of the particle having a small particle size in the size distribution of particles measured by laser diffraction. D10 is the size of the particle corresponding to 10% of the cumulative volume, calculated from the side of the particle having a small particle size in the size distribution of particles measured by laser diffraction.

[0034] In this disclosure, “metal” includes both metals and metalloids such as silicon and germanium, in their elemental or ionic states, and “alloy” in this disclosure means a mixture of two or more metals.

[0035] In the present disclosure, “electrode active material” means an electrode material capable of undergoing lithiation and delithiation.

[0036] In the present disclosure, “positive electrode active material” means a positive electrode material capable of undergoing lithiation and delithiation, and in the present disclosure, “negative electrode active material” means a negative electrode material capable of undergoing lithiation and delithiation.

[0037] In the present disclosure, “lithiation” and “lithiate” mean a process of adding lithium to an electrode active material, and in the present disclosure, “delithiation” and “delithiate” mean a process of removing lithium from an electrode active material.

[0038] In the present disclosure, “charging” and “charging” mean a process of providing electrochemical energy to a battery, and “discharging” and “discharging” in the present disclosure mean a process of removing electrochemical energy from a battery.

[0039] In the present disclosure, “positive electrode” and “cathode” mean an electrode where electrochemical reduction and lithiation occur during a discharge process, and in the present disclosure, “negative electrode” and “anode” mean an electrode where electrochemical oxidation and delithiation occur during a discharge process.

[0040] In the present disclosure, the aspect ratio represents the ratio (L1 / L2) of the major axis length L1 (e.g., length) and the minor axis length L2 (e.g., diameter). Here, the aspect ratio, major axis length, minor axis length, length, and diameter represent the average aspect ratio, average major axis length, average minor axis length, average length, and average diameter. The aspect ratio can be evaluated using a scanning electron microscope.

[0041] In the present disclosure, a "two-dimensional carbon nanostructure" is a carbon nanostructure in which two dimensions are significantly larger than one of the other dimensions. In other words, it is a carbon nanostructure in which the area defined by two dimensions is significantly larger than the thickness.

[0042] In the present disclosure, length and diameter represent average length and average diameter, respectively.

[0043] While specific implementations have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are not currently anticipated or unforeseen may occur to the applicant or those skilled in the art. Accordingly, the appended claims, as filed and as amended, are intended to encompass all such alternatives, modifications, variations, improvements, and substantial equivalents.

[0044] Hereinafter, an all-solid-state secondary battery according to exemplary implementation examples will be described in more detail.

[0045] [All-solid-state secondary battery]

[0046] According to one embodiment, an all-solid-state secondary battery includes a cathode layer; a cathode layer; a solid electrolyte layer between the cathode layer and the cathode layer; and a solid separator disposed at least between the cathode layer and the solid electrolyte layer and between the cathode layer and the solid electrolyte layer, wherein the cathode layer includes a cathode current collector and a first cathode active material layer on one surface of the cathode current collector, the solid electrolyte layer includes a sulfide-based solid electrolyte and an inorganic filler, the solid separator includes a porous membrane and an inorganic filler, and the inorganic filler includes a lithium metal oxyhalide represented by the following chemical formula 1.

[0047] <Chemical Formula 1>

[0048] Li a M b O c Cl d

[0049] In chemical formula 1, 0 <a≤3; 0<b≤3; 0<c≤3; 0<d≤8; c<d; a / (a+b+c+d)<0.5, M은 원소주기율표 3족 내지 15족에서 선택되는 금속이다.

[0050] All-solid-state secondary batteries can prevent short-circuiting, thermal runaway, and ignition of solid-state secondary batteries by shutting down the solid-state separator at high temperatures, including by including a solid-state separator. Consequently, the thermal stability and high-temperature safety of all-solid-state secondary batteries can be improved.

[0051] An all-solid-state secondary battery includes a solid separator, and the solid separator effectively accommodates changes in the volume of the all-solid-state secondary battery during the charge / discharge process, thereby suppressing increases in the internal resistance of the all-solid-state secondary battery. Consequently, deterioration of the all-solid-state secondary battery is prevented, and the charge / discharge characteristics of the all-solid-state secondary battery can be improved.

[0052] Since the solid separator has a low elastic modulus, it can accommodate the volume change of the all-solid-state secondary battery during charge and discharge, and effectively prevent electrical and / or ionic disconnection within the all-solid-state secondary battery despite the volume change of the all-solid-state secondary battery. It can also effectively suppress an increase in the internal resistance of the all-solid-state secondary battery during charge and discharge, for example, an increase in the interfacial resistance between the solid electrolyte layer and the positive and / or negative electrode layers. As a result, deterioration of the all-solid-state secondary battery can be suppressed, and charge and discharge characteristics can be improved.

[0053] The solid membrane contains an inorganic filler. Because the inorganic filler possesses ionic conductivity, the solid membrane can simultaneously provide flexibility and ionic conductivity. This solid membrane effectively suppresses the increase in internal resistance of an all-solid-state secondary battery by providing an excellent ionic conductive network. Consequently, the charge-discharge characteristics of the all-solid-state secondary battery can be improved.

[0054] By placing a solid separator between the positive electrode layer and / or negative electrode layer and the solid electrolyte layer, the growth of lithium dendrites precipitated between the solid electrolyte layer and the positive electrode layer and / or negative electrode layer during the charge / discharge process of the all-solid-state secondary battery can be more effectively blocked. Accordingly, deterioration of the solid electrolyte layer, such as cracks caused by the growth of lithium dendrites, can be more effectively blocked. As a result, the charge / discharge characteristics of the all-solid-state secondary battery can be further improved.

[0055] When lithium sulfide is used as the positive electrode active material, the positive electrode may expand and contract during charge and discharge, and the negative electrode may expand and contract. If the solid electrolyte layer positioned between the positive and negative electrodes, which have large volume changes, does not change in volume, and uneven volume expansion occurs during continuous charge and discharge, cracks may occur in the solid electrolyte layer, or resistance may increase due to delamination at the interface between the positive electrode and the solid electrolyte layer and / or the negative electrode and the solid electrolyte layer. As a result, the life characteristics of the all-solid-state secondary battery may deteriorate.

[0056] Accordingly, the present disclosure provides an all-solid-state secondary battery using a solid electrolyte layer including a sulfide-based solid electrolyte and an inorganic filler. The all-solid-state secondary battery includes the above-described solid electrolyte layer, and the inorganic filler blocks pores between particles of the sulfide-based solid electrolyte in the solid electrolyte layer to control pinholes in the solid electrolyte layer. As the pinholes are reduced in this way, cracks during charge and discharge are reduced, and the solid electrolyte layer effectively accommodates changes in the volume of the all-solid-state secondary battery during the charge and discharge process, thereby suppressing an increase in the internal resistance of the all-solid-state secondary battery. As a result, deterioration of the all-solid-state secondary battery can be prevented, and charge and discharge characteristics and rate characteristics of the all-solid-state secondary battery can be improved.

[0057] Since the solid electrolyte layer has a low elastic modulus, it can accommodate the volume change of the all-solid-state secondary battery during charge and discharge, and effectively prevent electrical and / or ionic disconnection within the all-solid-state secondary battery despite the volume change of the all-solid-state secondary battery. It can also effectively suppress an increase in the internal resistance of the all-solid-state secondary battery during charge and discharge, for example, an increase in the interfacial resistance between the solid electrolyte layer and the positive and / or negative electrode layers. As a result, deterioration of the all-solid-state secondary battery can be suppressed, and charge and discharge characteristics can be improved.

[0058] The solid electrolyte layer comprises an inorganic filler, and since the inorganic filler possesses ionic conductivity, the solid electrolyte layer can simultaneously provide flexibility and ionic conductivity. By providing an excellent ionic conductive network, the solid electrolyte layer can effectively suppress increases in the internal resistance of the all-solid-state secondary battery. Consequently, the charge-discharge characteristics of the all-solid-state secondary battery can be improved.

[0059] By disposing the above-described solid electrolyte layer between the positive and negative electrode layers, the growth of lithium dendrites precipitated between the solid electrolyte layer and the positive and / or negative electrode layers during the charge and discharge process of the all-solid-state secondary battery can be more effectively blocked. Accordingly, deterioration of the solid electrolyte layer, such as cracks caused by the growth of lithium dendrites, can be more effectively blocked. Consequently, the charge and discharge characteristics of the all-solid-state secondary battery can be further improved.

[0060] Referring to FIGS. 1 to 12, an all-solid-state secondary battery (1) includes a cathode layer (10); a cathode layer (20); a solid electrolyte layer (30) between the cathode layer (10) and the cathode layer (20); and a solid separator (40) disposed at least between the cathode layer (10) and the solid electrolyte layer (30) and between the cathode layer (20) and the solid electrolyte layer (30). The cathode layer (10) includes a cathode current collector (11) and a cathode active material layer (12) on one or both surfaces of the cathode current collector (11). The cathode active material layer (12) includes a cathode active material and a first solid electrolyte. The solid separator (40) may contain an inorganic filler or an inorganic filler and a sulfide-based solid electrolyte. The inorganic filler includes a lithium metal oxyhalide represented by the following chemical formula 1. The negative electrode layer (20) includes a negative electrode current collector (21) and a first negative electrode active material layer (22) on one surface of the negative electrode current collector (21).

[0061] In addition, the solid electrolyte layer (30) includes a sulfide-based solid electrolyte and an inorganic filler. The inorganic filler includes lithium metal oxyhalide represented by the following chemical formula 1.

[0062] <Chemical Formula 1>

[0063] Li a M b O c Cl d

[0064] In chemical formula 1, 0 <a≤3; 0<b≤3; 0<c≤3; 0<d≤8; c<d; a / (a+b+c+d)<0.5, M은 원소주기율표 3족 내지 15족에서 선택되는 금속이다.

[0065] The negative electrode layer (20) includes a negative electrode current collector (21) and a first negative electrode active material layer (22) on one surface of the negative electrode current collector (21).

[0066] The solid electrolyte layer (30) is in a solid state at room temperature. The solid electrolyte layer (30) includes an inorganic filler, and the inorganic filler melts at high temperatures. The solid electrolyte layer is, for example, a flexible film. In this way, since the solid electrolyte layer is a flexible film, the volume change of the all-solid-state secondary battery (1) can be effectively accommodated during charging and discharging of the all-solid-state secondary battery (1), and an increase in the interface resistance within the all-solid-state secondary battery (1) can be more effectively suppressed.

[0067] The solid separation membrane (40) can be liquid at, for example, 120°C or higher, 125°C or higher, 130°C or higher, 135°C or higher, 140°C or higher, 145°C or higher, 150°C or higher, 155°C or higher, 160°C or higher, 170°C or higher, 180°C or higher, or 200°C or higher. The solid separation membrane (40) can be solid at, for example, 100°C or lower, 80°C or lower, 70°C or lower, 60°C or lower, or 50°C or lower. The solid separation membrane (40) is solid at room temperature. The solid separation membrane (40) includes a porous membrane and an inorganic filler, and the porous membrane and the inorganic filler are melted at high temperatures. The porous membrane (40) melts at high temperatures to block pores and insulate between the positive electrode layer (10) / negative electrode layer (20) and the solid electrolyte layer (40), thereby effectively preventing short circuits, thermal runaway, and ignition of the all-solid-state secondary battery (1) at high temperatures.

[0068] [Solid separation membrane]

[0069] Referring to FIGS. 1 to 12, the all-solid-state secondary battery includes a solid separator (40, 40a, 40b), and the solid separator contains a porous membrane.

[0070] The shutdown temperature of the porous membrane may be 100°C or higher, 105°C or higher, 110°C or higher, 115°C or higher, 120°C or higher, 125°C or higher, 130°C or higher, 135°C or higher, 140°C or higher, 145°C or higher, 150°C or higher, 155°C or higher, or 160°C or higher. Since the porous membrane has a shutdown temperature within this range, short-circuiting, thermal runaway, ignition, etc. of the all-solid-state secondary battery (1) can be effectively prevented. Accordingly, the high-temperature safety of the all-solid-state secondary battery (1) can be further improved. The shutdown temperature can be measured, for example, according to the method described in Evaluation Example 1.

[0071] Melting point (T) of the porous membrane m) may be, for example, 120°C or higher, 125°C or higher, 130°C or higher, 135°C or higher, 140°C or higher, 145°C or higher, 150°C or higher, 155°C or higher, 160°C or higher, 170°C or higher, 180°C or higher, or 200°C or higher. Since the porous film has a melting point in this range, it can effectively prevent short circuit, thermal runaway, ignition, etc. of the all-solid-state secondary battery (1). Therefore, the high-temperature safety of the all-solid-state secondary battery (1) can be further improved. The melting point can be measured, for example, using a DSC (Differential Scanning Calorimeter).

[0072] The porous membrane may be, for example, a flexible porous membrane. Since the porous membrane is a flexible porous membrane, it can effectively accommodate changes in the volume of the all-solid-state secondary battery (1) during charging and discharging, and more effectively suppress an increase in the interfacial resistance within the all-solid-state secondary battery (1).

[0073] The porous membrane may include, for example, polyolefin. Polyolefin has excellent short-circuit prevention effect and can also improve the stability of the all-solid-state secondary battery (1) due to its shutdown effect. For example, the porous membrane may be a membrane made of a resin such as polyolefin, such as polyethylene, polypropylene, polybutene, polyvinyl chloride, and mixtures or copolymers thereof, but is not necessarily limited thereto, and any porous membrane that can be used in the relevant technical field may be used. For example, a porous membrane made of a polyolefin resin; a porous membrane obtained by weaving polyolefin fibers; a non-woven fabric including polyolefin; an aggregate of insulating material particles, etc. may be used. For example, a porous membrane including polyolefin has excellent applicability of a binder solution for producing a coating layer formed on the porous membrane, and can increase the capacity per unit volume by increasing the ratio of electrode active materials in an all-solid-state secondary battery (1) by making the film thickness of the composite membrane thinner.

[0074] Polyolefins can be homopolymers, copolymers, or mixtures thereof, such as polyethylene or polypropylene, for example. Polyethylene can be low-density, medium-density, or high-density polyethylene, and from the standpoint of mechanical strength, high-density polyethylene can be used. In addition, two or more types of polyethylene can be mixed for the purpose of providing flexibility. The polymerization catalyst used in the preparation of polyethylene is not particularly limited, and a Ziegler-Natta catalyst, a Phillips catalyst, a metallocene catalyst, etc. can be used. From the standpoint of achieving both mechanical strength and high permeability, the weight average molecular weight of polyethylene can be, for example, 100,000 to 12,000,000 Daltons, 100,000 to 8,000,000 Daltons, 100,000 to 5,000,000 Daltons, or 200,000 to 3,000,000 Daltons. Polypropylene can be a homopolymer, a random copolymer, or a block copolymer, and can be used alone or in combination of two or more. In addition, the polymerization catalyst is not particularly limited, and a Ziegler-Natta catalyst or a metallocene catalyst, etc. can be used. In addition, the stereoregularity is not particularly limited, and isotactic, syndiotactic, or atactic can be used, but inexpensive isotactic polypropylene can be used. Polyolefins can be added with additives such as polyethylene or polyolefins other than polypropylene and antioxidants.

[0075] The porous membrane may include, for example, a polyolefin such as polyethylene or polypropylene, and a multilayer membrane having two or more layers may be used. The porous membrane may be, but is not limited to, a mixed multilayer membrane such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, a polypropylene / polyethylene / polypropylene three-layer separator, etc., and any material and configuration that can be used as a porous substrate in the relevant technical field may be used.

[0076] The porous membrane may include a diene polymer prepared by polymerizing a monomer composition including, for example, a diene monomer. The diene monomer may be a conjugated diene monomer or a non-conjugated diene monomer. For example, the diene monomer includes, but is not limited to, one or more selected from the group consisting of 1,3-butadiene, isoprene, 2-chloro-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, chloroprene, vinylpyridine, vinylnorbornene, dicyclopentadiene, and 1,4-hexadiene, and any monomer that can be used as a diene monomer in the relevant technical field may be used.

[0077] The porous membrane may be, for example, an insulating porous membrane. Since the porous membrane is an insulating porous membrane, the pores can be sealed by melting the porous membrane at high temperatures to form an insulating layer. Consequently, the all-solid-state secondary battery (1) can be shut down and short-circuiting, thermal runaway, ignition, etc. of the all-solid-state secondary battery (1) can be effectively prevented.

[0078] The porous membrane may be, for example, a flame-retardant porous membrane. The porous membrane may be, for example, a flame-retardant inert porous membrane. Since the porous membrane is a flame-retardant and / or inert porous membrane, ignition of the solid-state secondary battery (1) at high temperatures can be more effectively prevented. The porous membrane may further include a flame retardant.

[0079] The flame-retardant inert porous membrane may further include, for example, a matrix and an additive. The matrix includes, for example, a substrate and a reinforcing material. The matrix includes, for example, a fibrous substrate and a fibrous reinforcing material. Since the matrix includes the substrate, the matrix may have elasticity. Therefore, the matrix can effectively accommodate volume changes during charge and discharge of the all-solid-state secondary battery (1) and can be arranged at various positions. The substrate included in the matrix includes, for example, a first fibrous material. Since the substrate includes the first fibrous material, the volume changes occurring during charge and discharge of the all-solid-state secondary battery (1) can be effectively accommodated and deformation of the porous membrane due to volume changes of the all-solid-state secondary battery (1) can be effectively suppressed. The first fibrous material is, for example, a material having an aspect ratio of 5 or more, 20 or more, or 50 or more. The first fibrous material is, for example, a material having an aspect ratio of 5 to 1000, 20 to 1000, or 50 to 1000. The first fibrous material is, for example, an insulating material. Since the first fibrous material is an insulating material, a short circuit between the positive electrode (30) and the negative electrode (20) caused by lithium dendrites, etc., generated during the charge / discharge process of the all-solid-state secondary battery (1) can be effectively prevented. The first fibrous material includes, for example, at least one selected from pulp fibers, insulating polymer fibers, and ion-conductive polymer fibers. The strength of the matrix is ​​improved by the inclusion of a reinforcing material in the matrix. Therefore, the matrix can prevent excessive volume change during charge / discharge of the all-solid-state secondary battery (1) and deformation of the all-solid-state secondary battery (1). The reinforcing material included in the matrix includes, for example, a second fibrous material. Since the reinforcing material includes the second fibrous material, the strength of the matrix can be increased more uniformly. The second fibrous material is, for example, a material having an aspect ratio of 3 or more, 5 or more, or 10 or more.The first fibrous material is, for example, a material having an aspect ratio of 3 to 100, 5 to 100, or 10 to 100. The second fibrous material is, for example, a flame-retardant material. Since the second fibrous material is a flame-retardant material, ignition due to thermal runaway occurring during the charge / discharge process of the all-solid-state secondary battery (1) or due to external impact can be effectively suppressed. The second fibrous material is, for example, glass fiber, metal oxide fiber, ceramic fiber, etc.

[0080] The flame-retardant inert porous membrane may further include an additive in addition to the matrix. The filler may be disposed within the matrix, on the surface of the matrix, or on both the interior and the surface. The additive is, for example, an inorganic material. The additive included in the flame-retardant inert solid separator is, for example, a moisture getter. The additive removes moisture remaining in the all-solid-state secondary battery (1) by adsorbing moisture, for example, at a temperature below 100°C, thereby preventing deterioration of the all-solid-state secondary battery (1). When the temperature of the all-solid-state secondary battery (1) increases to 150°C or higher due to thermal runaway occurring during the charge / discharge process of the all-solid-state secondary battery (1) or an external impact, the additive releases the adsorbed moisture, thereby effectively suppressing ignition of the all-solid-state secondary battery (1). The additive is, for example, a flame retardant. The additive is, for example, a metal hydroxide having moisture adsorption properties. The metal hydroxide contained in the additive is, for example, Mg(OH)2, Fe(OH)3, Sb(OH)3, Sn(OH)4, TI(OH)3, Zr(OH)4, Al(OH)3, or a combination thereof. The content of the additive contained in the flame-retardant inert porous membrane is, for example, 10 to 80 parts by weight, 20 to 80 parts by weight, 30 to 80 parts by weight, 40 to 80 parts by weight, 50 to 80 parts by weight, 60 to 80 parts by weight, or 65 to 80 parts by weight, based on 100 parts by weight of the flame-retardant inert porous membrane.

[0081] The thickness of the porous membrane may be, for example, 1 to 200 ㎛, 1 to 100 ㎛, 1 to 50 ㎛, 1 to 30 ㎛, 3 to 30 ㎛, 5 to 30 ㎛, 5 to 25 ㎛, or 15 to 25 ㎛. If the thickness of the porous membrane is too thin, it may be difficult to maintain the mechanical properties of the porous membrane, and if the thickness of the porous membrane is too thick, the energy density of the all-solid-state secondary battery (1) may be reduced. The thickness of the porous membrane can be measured, for example, with a micrometer. The thickness of the porous membrane can be measured, for example, according to ASTM D374.

[0082] The porosity of the porous membrane may be, for example, 20 to 99 vol%, 30 to 95 vol%, 30 to 80 vol%, or 40 to 70 vol%. If the porosity is too low, the internal resistance of the solid separation membrane (40) may increase excessively. If the porosity of the porous membrane is too high, it may be difficult to maintain the mechanical properties of the porous membrane. The porosity of the porous membrane can be measured, for example, by a nitrogen adsorption method. The porosity of the porous membrane can be calculated, for example, by measuring the volume and weight of the porous membrane to calculate the film density (d1) of the porous membrane, and the true density (d0) of the porous membrane material and the measured film density (d1) of the porous membrane can be calculated using the following mathematical formula 1.

[0083] <Mathematical Formula 1>

[0084] Porosity (%) = (d0-d1) / d0×100.

[0085] The pore size of the porous membrane may be, for example, 0.01 to 10 μm, 0.01 to 5 μm, 0.01 to 2 μm, 0.01 to 1 μm, 0.01 to 0.5 μm, or 0.1 to 0.5 μm. If the pore size of the porous membrane is too small, the internal resistance of the electrolyte layer (30) may excessively increase, and if the pore size of the porous substrate is excessively large, the possibility of a short circuit in the secondary battery may increase. The pore size of the porous membrane can be measured, for example, by a nitrogen adsorption method.

[0086] [Solid electrolyte layer]

[0087] [Solid electrolyte layer: inorganic filler]

[0088] Referring to FIGS. 1 to 12, the solid electrolyte layer (30) includes an inorganic filler.

[0089] Inorganic fillers can be impregnated into the pores of, for example, a sulfide-based solid electrolyte. The size of the inorganic filler can be controlled to be small compared to the size of the sulfide-based solid electrolyte. The size of the inorganic filler is selected, for example, within a range of 0.1 μm to 3 μm.

[0090] The sulfide-based solid electrolyte is selected in the size range of 1 to 3 μm. The sulfide-based solid electrolyte may contain a bimodal solid electrolyte. For example, it may contain a small-particle-size first sulfide-based solid electrolyte and a large-particle-size second sulfide-based solid electrolyte.

[0091] The average particle diameter (D50) of the small-diameter first sulfide-based solid electrolyte is 0.5 to 1.9 μm, and the average particle diameter (D50) of the large-diameter first sulfide-based solid electrolyte is 2 to 5 μm. When a solid electrolyte layer is formed using a bimodal sulfide-based solid electrolyte in this way, the internal pores of the solid electrolyte layer are reduced, so that the density of the solid electrolyte layer can be increased. Therefore, by using such a solid electrolyte layer, an all-solid-state secondary battery with improved energy density, rate characteristics, and cycle life characteristics can be manufactured.

[0092] The inorganic filler may be, for example, an amorphous lithium metal oxyhalide. After preparing a crystalline inorganic filler, the crystalline inorganic filler may be melted to prepare a molten salt, which may then be cooled to prepare the amorphous inorganic filler. Alternatively, the amorphous inorganic filler may be directly prepared by controlling the composition during the preparation of the inorganic filler. After preparing a crystalline lithium metal oxyhalide, the crystalline lithium metal oxyhalide may be melted to prepare a molten salt, which may then be cooled to prepare the amorphous lithium metal oxyhalide. Alternatively, the amorphous lithium metal oxyhalide may be directly prepared by controlling the composition during the preparation of the lithium metal oxyhalide. The amorphous inorganic filler may have, for example, ductility. Since the amorphous inorganic filler has ductility, it can more effectively accommodate volume changes during charge and discharge of the all-solid-state secondary battery (1). In contrast, crystalline lithium metal oxyhalides may be relatively brittle compared to amorphous lithium metal halides. The amorphous nature of an inorganic filler can be confirmed using an XRD spectrum.

[0093] The inorganic filler may be, for example, glassy. The inorganic filler may be, for example, a glassy lithium metal oxyhalide having a glass transition temperature (Tg). The glassy lithium metal oxyhalide may have ductility. Since the inorganic filler has ductility, the volume change of the all-solid-state secondary battery (1) can be effectively accommodated during charge and discharge, or the all-solid-state secondary battery (1) can be easily deformed according to the volume change.

[0094] The glass transition temperature of the inorganic filler may be, for example, 20°C or lower, 10°C or lower, 0°C or lower, or -10°C or lower. Because the inorganic filler has such a low glass transition temperature, it can easily transition from a brittle, crystalline metal salt state to a ductile, glassy state. For example, the inorganic filler can be easily transitioned from a crystalline, molten salt state to a glassy state by melting and then cooling it. Alternatively, the glassy state can be obtained during the manufacturing process of the inorganic filler. The glass transition temperature can be measured, for example, using a differential scanning calorimeter (DSC). The glass transition temperature can be measured, for example, using a dynamic mechanical analyzer (DMA).

[0095] The melting point of the inorganic filler may be, for example, 100°C or higher, 105°C or higher, 110°C or higher, 115°C or higher, 120°C or higher, 125°C or higher, 130°C or higher, 135°C or higher, 140°C or higher, or 145°C or higher. The melting point of the inorganic filler may be, for example, 200°C or lower, 190°C or lower, 180°C or lower, 170°C or lower, 160°C or lower, or 150°C or lower. Since the inorganic filler has a melting point within this range, the inorganic filler can be melted to form a molten salt state and then cooled to easily produce an amorphous inorganic filler. The melting point of the inorganic filler can be measured, for example, using differential scanning calorimetry (DSC).

[0096] The inorganic filler may be an ionic conductive inorganic filler. The inorganic filler may have, for example, an ionic conductivity of 0.01 mS / cm or more, 0.05 mS / cm or more, 0.1 mS / cm or more, 0.3 mS / cm or more, 0.5 mS / cm or more, 0.7 mS / cm or more, or 1.0 mS / cm or more at 25°C and 1 atm. The ionic conductivity may be measured by AC impedance analysis. The voltage amplitude used in the AC impedance analysis may be 5 to 10 mV, and the frequency may be 1 MHz to 1 Hz. Since the inorganic filler has ionic conductivity, it can effectively suppress an increase in the interfacial resistance between the sulfide-based solid electrolyte within the solid electrolyte layer.

[0097] The elastic modulus (elastic modulus or Young's modulus) of the inorganic filler at 30°C may be 10 GPa or less, 5 GPa or less, 3 GPa or less, or 2 GP a or less. Since the inorganic filler has an elastic modulus in this low range, the solid electrolyte layer including the inorganic filler can effectively accommodate the volume change of the all-solid-state secondary battery (1). Accordingly, the cycle characteristics of the all-solid-state secondary battery (1) can be improved. The elastic modulus of the inorganic filler can be measured, for example, using a dynamic mechanical analyzer (DMA).

[0098] The elastic modulus of the inorganic filler may be smaller than, for example, the elastic modulus (elastic modulus or Young's modulus) of the sulfide-based solid electrolyte. The elastic modulus of the sulfide-based solid electrolyte at 30°C may be, for example, 22 to 30 GPa. The elastic modulus of the inorganic filler may be, for example, 90% or less, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less of the elastic modulus of the sulfide-based solid electrolyte. The inorganic filler may be additionally disposed on the positive electrode active material layer (20). In such an all-solid-state secondary battery (1), since the inorganic filler has a lower elastic modulus than the sulfide-based solid electrolyte, the inorganic filler can easily fill the pores between the sulfide-based solid electrolyte and / or the pores between the sulfide-based solid electrolyte and the positive electrode active material, thereby reducing the internal resistance of the positive electrode active material layer (12) and easily accommodating the volume change of the positive electrode active material layer (12) during charge and discharge. As a result, the cycle characteristics of the all-solid-state secondary battery (1) can be further improved. The elastic modulus of the sulfide-based solid electrolyte can be measured, for example, using a dynamic mechanical analyzer (DMA).

[0099] Inorganic fillers can have, for example, viscoelasticity. Inorganic fillers can have, for example, viscoelastic creep. The viscoelastic creep rate of an inorganic filler can be, for example, 1×10 -4 % / s or more, 2×10 -4 % / s or more or 4×10 -4% / s or more. % / s is the ratio of the transformed size to the initial size per unit time (second). Since the inorganic filler has viscoelasticity, it can easily accommodate the change in volume during charging and discharging of the all-solid-state secondary battery (1) and can continuously transform the shape without defects. The creep rate is the change rate over time of the inorganic filler under stress at a constant temperature, i.e., the deformation speed. The creep rate can be measured using, for example, a universal testing machine.

[0100] Weapon filler is Li a M b O c Cl d (0 <a≤3; 0<b≤3; 0<c≤3; 0<d≤8; c<d; a / (a+b+c+d)<0.5, M은 원소주기율표 3족 내지 15족에서 선택되는 금속)로 표시되는 리튬금속옥시할라이드(lithium metal oxyhalide)를 포함한다. 예를 들어, Li a M b O c Cl d 0 in <a≤2; 0<b≤2.5; 0<c≤2.5; 0<d≤7; c<d; a / (a+b+c+d)<0.5이다. 예를 들어, Li a M b O c Cl d 0 in <a≤1.5; 0<b≤3; 0<c≤2; 0<d≤6; c<d; a / (a+b+c+d)<0.5 이다. 예를 들어, Li a M b O c Cl d 0 in <a≤1; 0<b≤2.5; 0<c≤1.5; 0<d≤5; c<d; a / (a+b+c+d)<0.5 이다. 예를 들어, Li a M b O c Cl d 0 in <a≤1; 0<b≤2; 0<c≤1; 0<d≤4; c<d; a / (a+b+c+d)<0.5 이다.

[0101] The metal M of the lithium metal oxyhalide may include, for example, Fe, Ga, In, As, Sb, Mo, Bi, B, or a combination of two or more thereof.

[0102] Lithium metal oxyhalides are, for example, LiAl b O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiFe b O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiGa b O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiIn b O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiAs b O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiSb b O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiMo b O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiBi b O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiB b O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiAl b-e Fe e O c Cld (0 <b≤3; 0<c≤2; 0<d≤4; 0<e<b; c<d; 1 / (1+b+c+d+e) <0.5); LiAl b-e Ga e O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; 0<e<b; c<d; 1 / (1+b+c+d+e) <0.5); LiAl b-e In e O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; 0<e<b; c<d; 1 / (1+b+c+d+e) <0.5); LiAl b-e As e O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; 0<e<b; c<d; 1 / (1+b+c+d+e) <0.5); LiAl b-e Sb e O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; 0<e<b; c<d; 1 / (1+b+c+d+e) <0.5); LiAl b-e Mo e O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; 0<e<b; c<d; 1 / (1+b+c+d+e) <0.5); LiAl b-e Bi e O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; 0<e<b; c<d; 1 / (1+b+c+d+e) <0.5); LiAl b-e B e O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; 0<e<b; c<d; 1 / (1+b+c+d+e) <0.5) 또는 이들의 조합을 포함할 수 있다.

[0103] Lithium metal oxyhalides are, for example, LiAl x O z Cl w(0 <x≤2; 0<z≤1; 2<w<4; z<w; z<w, 1 / (1+x+z+w) <0.5), LiFe x O z Cl w (0 <x≤2; 0<z≤1; 2<w<4; z<w, 1 / (1+x+z+w) <0.5), LiGa x O z Cl w (0 <x≤2; 0<z≤1; 2<w<4; z<w, 1 / (1+x+z+w) <0.5), LiIn x O z Cl w (0 <x≤2; 0<z≤1; 2<w<4; z<w, 1 / (1+x+z+w) <0.5), LiAs x O z Cl w (0 <x≤2; 0<z≤1; 2<w<4; z<w, 1 / (1+x+z+w) <0.5), LiSb x O z Cl w (0 <x≤2; 0<z≤1; 2<w<4; z<w, 1 / (1+x+z+w) <0.5), LiMo x O z Cl w (0 <x≤2; 0<z≤1; 2<w<4; z<w, 1 / (1+x+z+w) <0.5), LiBi x O z Cl w (0 <x≤2; 0<z≤1; 2<w<4; z<w, 1 / (1+x+z+w) <0.5), LiB x O z Cl w (0 <x≤2; 0<z≤1; 2<w<4; z<w, 1 / (1+x+z+w) <0.5) 또는 이들의 조합을 포함할 수 있다.

[0104] Lithium oxyhalides are, for example, LiAl x Fe y O z Cl w (0 <x≤2; 0≤y<1; 0<z≤1; 2<w<4; z<w, 1 / (1+x+y+z+w)<0.5), LiAl x Ga y Oz Cl w (0 <x≤2; 0≤y<1; 0<z≤1; 2<w<4; z<w, 1 / (1+x+y+z+w)<0.5), LiAl x In y O z Cl w (0 <x≤2; 0≤y<1; 0<z≤1; 2<w<4; z<w, 1 / (1+x+y+z+w)<0.5), LiAl x As y O z Cl w (0 <x≤2; 0≤y<1; 0<z≤1; 2<w<4; z<w, 1 / (1+x+y+z+w)<0.5), LiAl x Sb y O z Cl w (0 <x≤2; 0≤y<1; 0<z≤1; 2<w<4; z<w, 1 / (1+x+y+z+w)<0.5), LiAl x Mo y O z Cl w (0 <x≤2; 0≤y<1; 0<z≤1; 2<w<4; z<w, 1 / (1+x+y+z+w)<0.5), LiAl x Bi y O z Cl w (0 <x≤2; 0≤y<1; 0<z≤1; 2<w<4; z<w, 1 / (1+x+y+z+w)<0.5), LiAl x B y O z Cl w (0 <x≤2; 0≤y<1; 0<z≤1; 2<w<4; z<w, 1 / (1+x+y+z+w)<0.5) 또는 이들의 조합을 포함할 수 있다.

[0105] Compounds of formula 1 are, for example, LiAlCl 2.5 O 0.75 , LiAl 1.3 Cl 2.7 O 1.1 , LiAl 1.25 As 0.09 O 1.18 Cl 2.66 , LiGa 0.4 In0.7 Sb 0.04 O 1.05 Cl 2.32 , LiAl 1.25 As 0.09 O 1.18 Cl 2.66 Or a combination thereof.

[0106] The content of the inorganic filler in the solid electrolyte layer is 1 to 15 parts by weight, 3 to 10 parts by weight, or 5 to 10 parts by weight based on 100 parts by weight of the total weight of the solid electrolyte layer. If the content of the inorganic filler is excessively low, the internal resistance of the solid electrolyte layer (30) may excessively increase. If the content of the inorganic filler is excessively high, the shutdown effect of the solid electrolyte layer (30) may be reduced.

[0107] In the solid electrolyte layer according to one embodiment, the sulfide-based solid electrolyte includes a small-diameter first sulfide-based solid electrolyte having an average particle diameter (D50) of 0.5 to 1.9 μm and a large-diameter first sulfide-based solid electrolyte having an average particle diameter (D50) of 2 to 5 μm. The average particle diameter of the solid electrolyte in the present disclosure can be measured, for example, using a laser diffraction method. More specifically, after dispersing the positive active material or the solid electrolyte in a solution, the dispersion is introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), and ultrasonic waves of about 28 kHz are irradiated at an output of 60 W, and then the average particle diameter (D50) based on 50% of the particle diameter distribution in the measuring device can be calculated.

[0108] The content of the small-particle-size first sulfide-based solid electrolyte is greater than the content of the large-particle-size second sulfide-based solid electrolyte. The mixing weight ratio of the small-particle-size first sulfide-based solid electrolyte and the large-particle-size second sulfide-based solid electrolyte is 1.5:1 to 7:1, 2:1 to 5:1, or 3:1 to 4:1. When a solid electrolyte layer is formed using a bimodal sulfide-based solid electrolyte in this way, the internal pores of the solid electrolyte layer can be reduced, thereby increasing the density of the solid electrolyte layer. Therefore, by using such a solid electrolyte layer, an all-solid-state secondary battery with improved energy density, rate characteristics, and cycle life characteristics can be manufactured.

[0109] According to another embodiment, a solid electrolyte layer of an all-solid-state secondary battery may include a first solid electrolyte layer including a sulfide-based solid electrolyte and an inorganic filler, and a second solid electrolyte layer including a sulfide-based solid electrolyte and an inorganic filler. Here, the first solid electrolyte layer is arranged to be in contact with the negative electrode, the second solid electrolyte layer is arranged to be in contact with the positive electrode, and the content of the inorganic filler in the first solid electrolyte layer is adjusted to be smaller than the content of the inorganic filler in the first solid electrolyte layer. When the inorganic filler in the solid electrolyte layer has the above-described content distribution, the low-voltage characteristics are improved.

[0110] According to one embodiment, the content of the inorganic filler in the first solid electrolyte layer is 1 to 15 parts by weight, or 1 to 5 parts by weight, based on 100 parts by weight of the first solid electrolyte layer. According to one embodiment, the content of the inorganic filler in the second solid electrolyte layer is 1 to 15 parts by weight, or 5 to 15 parts by weight, based on 100 parts by weight of the second solid electrolyte layer.

[0111] [Solid electrolyte layer: solid electrolyte]

[0112] Referring to FIGS. 1 to 12, an all-solid-state secondary battery (1) is disposed between a positive electrode layer (10) and a negative electrode layer (20), and includes a solid electrolyte layer (30) containing a sulfide-based solid electrolyte and an inorganic filler. The solid electrolyte layer (30) may further include, for example, a solid electrolyte, or a combination of a solid electrolyte and a gel electrolyte.

[0113] The solid electrolyte may include, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a polymer solid electrolyte, or a combination thereof.

[0114] The solid electrolyte is, for example, a sulfide-based solid electrolyte. A sulfide-based solid electrolyte has a higher density than a sulfide-based solid electrolyte, for example, 1×10 at room temperature. -5 It can have an ionic conductivity of S / cm or more. Sulfide-based solid electrolytes include, for example, Li3PO4-Li2SO4, 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, Z is one of Ge, Zn or Ga, Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q , p, q are positive numbers, 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, may include one or more selected from 0≤x≤2. The oxide-based solid electrolyte includes, for example, Li, O, and a transition metal element, and may optionally further include other elements. The oxide-based solid electrolyte may include, for example, 1×10 at room temperature. -5 It may be a solid electrolyte having an ionic conductivity of S / cm or more. The oxide-based solid electrolyte may be selected from oxide-based solid electrolytes used in the solid electrolyte layer. The solid electrolyte may be, for example, a mixture of a sulfide-based solid electrolyte and a lithium salt. For example, it may be a mixture of Li3PO4-Li2SO4 and a binary lithium salt, or a mixture of Li3PO4-Li2SO4 and a ternary lithium salt.

[0115] Oxide solid electrolytes include, for example, Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0≤x<1, 0≤y<1), PB(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Li3PO4, Li x Ti y (PO4)3(0 <x<2, 0<y<3), Li x Al y Ti z (PO4)3(0 <x<2, 0<y<1, 0<z<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1 0≤y≤1), Li x La yTiO3(0 <x<2, 0<y<3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2, Li 3+x La3M2O 12 (M = Te, Nb, or Zr, 0≤x≤10), or a combination thereof. The oxide-based solid electrolyte is manufactured, for example, by a sintering method.

[0116] Oxide-based solid electrolytes include, for example, Li7La3Zr2O 12 (LLZO) and Li 3+x La3Zr 2-a M a O 12 (M doped LLZO, M=Ga, W, Nb, Ta, or Al, 0 <a<2, 0≤x≤10) 중에서 선택된 가넷계(Garnet-type) 고체전해질이다.

[0117] The polymer solid electrolyte may, for example, comprise a mixture of a lithium salt and a polymer, or a polymer having ion-conducting functional groups. The polymer solid electrolyte may be, for example, a polymer electrolyte that is solid at 25°C and 1 atm. The polymer solid electrolyte may not, for example, comprise a liquid.The polymer solid electrolyte comprises a polymer, and the polymer is, for example, polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene (PVDF-HFP), poly(styrene-b-ethylene oxide) block copolymer (PS-PEO), poly(styrene-butadiene), poly(styrene-isoprene-styrene), poly(styrene-b-divinylbenzene) block copolymer, poly(styrene-ethylene oxide-styrene) block copolymer, polystyrene sulfonate (PSS), polyvinyl fluoride (PVF), polymethyl methacrylate (PMMA, poly(methylmethacrylate), polyethylene glycol (PEG), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), polyethylenedioxythiophene (PEDOT), polypyrrole (PPY), polyacrylonitrile (PAN), polyaniline, polyacetylene, Nafion, Aquivion, Flemion, Gore, Aciplex, Morgane ADP, sulfonated poly(ether ether ketone) (SPEEK), sulfonated poly(arylene ether ketone ketone sulfone) (SPAEKKS), sulfonated poly(aryl ether ketone) (SPAEK), poly[bis(benzimidazobenzisoquinolinones)] (SPBIBI), poly(styrene sulfonate) (PSS), or combinations thereof, but are not limited thereto. Anything that can be used as a polymer electrolyte in the technical field is acceptable. Any lithium salt that can be used as a lithium salt in the technical field is acceptable.Lithium salts include, for example, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, Li(FSO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C. x F 2x+1 SO2)(C y F 2y+1 SO2) (x and y are each 1 to 20), LiCl, LiI or a mixture thereof, etc. The polymer included in the polymer solid electrolyte may be, for example, a compound including 10 or more, 20 or more, 50 or more or 100 or more repeating units. The weight average molecular weight of the polymer included in the polymer solid electrolyte may be, for example, 1000 Dalton or more, 10,000 Dalton or more, 100,000 Dalton or more or 1,000,000 Dalton or more.

[0118] A gel electrolyte is, for example, a polymer gel electrolyte. A gel electrolyte can have a gel state without containing a polymer, for example.

[0119] The polymer gel electrolyte may include, for example, a liquid electrolyte and a polymer, or an organic solvent and a polymer having an ion-conducting functional group. The polymer gel electrolyte may be, for example, a polymer electrolyte that is in a gel state at 25°C and 1 atm. The polymer gel electrolyte may have a gel state, for example, without containing a liquid. The liquid electrolyte used in the polymer gel electrolyte may be, for example, an ionic liquid, a mixture of a lithium salt and an organic solvent; a mixture of a lithium salt and an organic solvent; a mixture of an ionic liquid and an organic solvent; or a mixture of a lithium salt, an ionic liquid, and an organic solvent. The polymer used in the polymer gel electrolyte may be selected from among the polymers used in solid polymer electrolytes. The organic solvent may be selected from among the organic solvents used in liquid electrolytes. The organic solvent is, for example, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether, or a mixture thereof. The lithium salt may be selected from lithium salts used in polymer solid electrolytes. Ionic liquids are salts that have a melting point below room temperature, are composed only of ions, and are liquid at room temperature or molten at room temperature.The ionic liquid may include, for example, one or more cations selected from among a) ammonium compounds, pyrrolidinium compounds, pyridinium compounds, pyrimidinium compounds, imidazolium compounds, piperidinium compounds, pyrazolium compounds, oxazolium compounds, pyridazinium compounds, phosphonium compounds, sulfonium compounds, triazolium compounds, and mixtures thereof, and b) one or more anions selected from among BF4-, PF6-, AsF6-, SbF6-, AlCl4-, HSO4-, ClO4-, CH3SO3-, CF3CO2-, Cl-, Br-, I-, SO4-, CF3SO3-, (FSO2)2N-, (C2F5SO2)2N-, (C2F5SO2)(CF3SO2)N-, and (CF3SO2)2N-. A polymer solid electrolyte can form a polymer gel electrolyte, for example, by being impregnated into a liquid electrolyte in a secondary battery. The polymer gel electrolyte can further include inorganic particles. The polymer included in the polymer gel electrolyte can be, for example, a compound containing 10 or more, 20 or more, 50 or more, or 100 or more repeating units. The weight average molecular weight of the polymer included in the polymer gel electrolyte can be, for example, 500 Dalton or more, 1000 Dalton or more, 10,000 Dalton or more, 100,000 Dalton or more, or 1,000,000 Dalton or more.

[0120] [Solid electrolyte layer: binder]

[0121] The solid electrolyte layer (30) may include, for example, a binder. The binder included in the solid electrolyte layer (30) is not limited to, but may include, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., and any binder used in the relevant technical field may be used. The binder of the solid electrolyte layer (30) may be the same as or different from the binder included in the positive electrode active material layer (12) and the negative electrode active material layer (22). The binder may be omitted.

[0122] The binder content included in the solid electrolyte layer (30) is 0.1 to 10 wt%, 0.1 to 5 wt%, 0.1 to 3 wt%, 0.1 to 1 wt%, 0 to 0.5 wt%, or 0 to 0.1 wt% with respect to the total weight of the solid electrolyte layer (30).

[0123] According to an embodiment, a solid electrolyte layer is prepared by mixing a sulfide-based solid electrolyte, an inorganic filler, and a binder to form a composition for forming a solid electrolyte layer. The composition for forming a solid electrolyte layer is provided on a substrate and heat-treated to form a solid electrolyte layer.

[0124] The above heat treatment can be performed at 50 to 200°C, 100 to 180°C, or 110 to 150°C. By performing this heat treatment step, voids in the solid electrolyte layer can be removed.

[0125] After the step of placing a solid electrolyte layer between the positive and negative electrodes, a step of obtaining a battery assembly and pressurizing it may be performed.

[0126] Pressurization is not limited to a roll press, a flat press, etc., but any pressurization method used in the relevant technical field may be used. The pressurization step may be omitted.

[0127] Pressurization is performed at a temperature of, for example, room temperature (20°C to 25°C) to 90°C. Alternatively, pressurization is performed at a high temperature of 100°C or higher. The pressurization time is, for example, 30 minutes or less, 20 minutes or less, 15 minutes or less, or 10 minutes or less. The pressurization time is 1 ms to 30 minutes, 1 ms to 20 minutes, 1 ms to 15 minutes, or 1 ms to 10 minutes. The pressurization method is, for example, isotactic press, roll press, flat press, etc., but is not necessarily limited to these methods and any pressurization method used in the art can be used. The pressure applied during pressurization is, for example, 500 MPa or less, for example, 400 MPa or less, 300 MPa or less, 200 MPa or less, 100 MPa or less, or 50 MPa. The pressure applied during pressurization is, for example, 1 to 50 MPa, 1 to 30 MPa, 1 to 20 MPa, or 1 to 10 MPa.

[0128] According to one embodiment, the heat treatment process for forming the above-described solid electrolyte layer can be omitted, and for example, the solid electrolyte powder can be sintered to form one solid electrolyte layer through a pressurizing process for manufacturing a battery.

[0129] The pressurizing step is for example 40 to 100°C, for example 85 o Plate press treatment is performed at a pressure of 500 MPa for 30 min at C. This pressurization treatment sinteres the solid electrolyte layer, thereby improving battery characteristics.

[0130] [Solid separation membrane: inorganic filler]

[0131] Referring to FIGS. 1 to 12, the solid separation membrane (40) includes an inorganic filler.

[0132] An inorganic filler can be impregnated into a porous membrane, for example. For example, a solid inorganic filler can be first heated to prepare a liquid inorganic filler. The liquid inorganic filler can then be applied to the porous membrane, thereby impregnating the porous membrane with the inorganic filler. The porous membrane impregnated with the inorganic filler can then be cooled to room temperature to produce a solid separation membrane. The inorganic filler can be impregnated into the pores of the porous membrane.

[0133] In a solid separation membrane, for example, the inorganic filler may be disposed within the pores of a porous membrane. The shape of the inorganic filler disposed within the pores of the porous membrane may substantially conform to the shape of the pores. The surface of the pores of the porous membrane may act as a kind of mold. Therefore, the shape of the inorganic filler disposed within the pores of the porous membrane may substantially conform to the shape of the pores, for example. In addition, the surface profile of the inorganic filler disposed within the pores of the porous membrane may substantially conform to the surface profile of the pores. The surface profile of the inorganic filler disposed within the pores of the porous membrane may substantially conform to the surface profile of the pores, for example.

[0134] The inorganic filler contained in the porous membrane may be the same as the inorganic filler of the solid electrolyte layer.

[0135] The volume ratio of the porous membrane and the inorganic filler may be, for example, 80:20 to 1:99, 70:30 to 5:95, 70:30 to 20:80 volume %, or 60:40 to 30:70. If the content of the inorganic filler is too low, the internal resistance of the solid separation membrane (40) may excessively increase. If the content of the inorganic filler is too high, the shutdown effect of the solid separation membrane (40) may be reduced.

[0136] The solid separation membrane (40) may contain a sulfide-based solid electrolyte in addition to an inorganic filler. When the solid separation membrane contains an inorganic filler and a sulfide-based solid electrolyte, the content of the inorganic filler is 1 to 15 wt%, and the content of the sulfide-based solid electrolyte is 85 to 99 wt%.

[0137] The above sulfide-based solid electrolyte can be the same as the sulfide-based solid electrolyte of the solid electrolyte layer.

[0138] [Anode layer]

[0139] Referring to FIGS. 1 to 10, the positive electrode (10) includes a positive electrode current collector (11); and a positive electrode active material layer (12) disposed on one or both sides of the positive electrode current collector (11). The positive electrode active material layer (12) includes a positive electrode active material and a first solid electrolyte.

[0140] [Cathode active material layer: Cathode active material]

[0141] The content of the positive electrode active material included in the positive electrode active material layer (12) may be, for example, 10 wt% to 99 wt%, 50 wt% to 99 wt%, 70 wt% to 95 wt%, or 80 wt% to 95 wt% of the total weight of the positive electrode active material layer (12). If the content of the positive electrode active material is excessively reduced, the energy density of the all-solid-state secondary battery (1) is lowered. If the content of the positive electrode active material is excessively increased, the deterioration of the all-solid-state secondary battery (1) may be accelerated due to a change in the volume of the positive electrode during charge and discharge.

[0142] The cathode active material included in the cathode active material layer (12) is a cathode active material that can reversibly absorb and desorb lithium ions.

[0143] The cathode active material includes, for example, an oxide-based cathode active material, a sulfide-based cathode active material, or a combination thereof.

[0144] The oxide-based cathode active material includes, for example, a lithium transition metal oxide, a metal oxide, or a combination thereof. The lithium transition metal oxide includes, for example, lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt mangense oxide, lithium manganate, lithium iron phosphate, or a combination thereof. The lithium oxide includes, for example, iron oxide, vanadium oxide, or a combination thereof.

[0145] Sulfide-based cathode active materials include, for example, nickel sulfide, copper sulfide, Li2S, Li2S-containing complexes, or combinations thereof.

[0146] The oxide-based cathode active material may be, for example, one or more composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof. The lithium-containing oxide-based cathode active material may be, for example, Li. a A 1-b B' b D2 (in the above formula, 0.90 ≤ a ≤ 1, and 0 ≤ b ≤ 0.5); Li a E 1-b B' b O 2-c D c (In the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE 2-b B' b O 4-c D c (In the above formula, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Lia Ni 1-b-c Co b B' c D α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Co b B' c O 2-α F' α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Co b B' c O 2-α F' α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B' c D α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Mn b B' c O 2-α F' α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B' c O 2-α F' α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni b E c G dO2 (in the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d G e O2 (in the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li a NiG b O2 (in the above formula, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (in the above formula, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a MnG b O2 (in the above formula, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (in the above formula, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); LiV2O5; LiI'O2; LiNiVO4; Li (3-f) J2(PO4)3(0 ≤ f ≤ 2); Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2); may include a compound represented by any one of the chemical formulas of LiFePO4.

[0147] In the chemical formula representing the above-described compound, A is Ni, Co, Mn, or a combination thereof; B' is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F' is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I' is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof. It is also possible to use a compound having a coating layer added to the surface of the above-described compound, or it is also possible to use a mixture of the above-described compound and the compound having a coating layer added. The coating layer added to the surface of the above-mentioned compound includes a coating element compound of, for example, an oxide, a hydroxide, an oxyhydroxide of the coating element, an oxycarbonate of the coating element, or a hydroxycarbonate of the coating element of the coating element. The compound forming the coating layer is amorphous or crystalline. The coating elements included in the coating layer are Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the positive electrode active material. The coating method includes, for example, spray coating and dipping. Since the specific coating method is well understood by those working in the relevant field, a detailed description thereof will be omitted.

[0148] The oxide-based cathode active material may include, for example, a lithium transition metal oxide represented by the following chemical formulas 2 to 9:

[0149] <Chemical Formula 2>

[0150] Li a Ni x Co y M z O2-b A b

[0151] In the above chemical formula 2, 1.0≤a≤1.2, 0≤b≤0.2, 0.8≤x<1, 0≤y≤0.3, 0 <z≤0.3, 및 x+y+z=1이고, M은 망간(Mn), 니오븀(Nb), 바나듐(V), 마그네슘(Mg), 갈륨(Ga), 실리콘(Si), 텅스텐(W), 몰리브덴(Mo), 철(Fe), 크롬(Cr), 구리(Cu), 아연(Zn), 티타늄(Ti), 알루미늄(Al), 보론(B) 또는 이들의 조합이고, A는 F, S, Cl, Br 또는 이들의 조합이며,

[0152] <Chemical Formula 3>

[0153] LiNi x Co y Mn z O2

[0154] <Chemical Formula 4>

[0155] LiNi x Co y Al z O2

[0156] In the above chemical formulas 3 and 4, 0.8≤x≤0.95, 0≤y≤0.2, 0 <z≤0.2 및 x+y+z=1이며,

[0157] <Chemical Formula 5>

[0158] LiNi x Co y Mn z Al w O2

[0159] In the above chemical formula 5, 0.8≤x≤0.95, 0≤y≤0.2, 0 <z≤0.2, 0<w≤0.2, 및 x+y+z+w=1이며,

[0160] <Chemical Formula 6>

[0161] Li a Co x M y O 2-b A b

[0162] In the above chemical formula 6, 1.0≤a≤1.2, 0≤b≤0.2, 0.9≤x≤1, 0≤y≤0.1, and x+y=1, M is manganese (Mn), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B) or a combination thereof, A is F, S, Cl, Br or a combination thereof,

[0163] <Chemical Formula 7>

[0164] Li a Ni x Mn y M' z O 2-b A b

[0165] In the above chemical formula 7, 1.0≤a≤1.2, 0≤b≤0.2, 0 <x≤0.3, 0.5≤y<1, 0<z≤0.3, 및 x+y+z=1이고, M'는 코발트(Co), 니오븀(Nb), 바나듐(V), 마그네슘(Mg), 갈륨(Ga), 실리콘(Si), 텅스텐(W), 몰리브덴(Mo), 철(Fe), 크롬(Cr), 구리(Cu), 아연(Zn), 티타늄(Ti), 알루미늄(Al), 보론(B) 또는 이들의 조합이고, A는 F, S, Cl, Br 또는 이들의 조합이며,

[0166] <Chemical Formula 8>

[0167] Li a M1 x M2 y PO 4-b X b

[0168] In the above chemical formula 8, 0.90≤a≤1.1, 0≤x≤0.9, 0≤y≤0.5, 0.9 <x+y<1.1, 0≤b≤2이며, M1이 크롬(Cr), 망간(Mn), 철(Fe), 코발트(Co), 니켈(Ni), 구리(Cu), 지르코늄(Zr) 또는 이들의 조합이며, M2가 마그네슘(Mg), 칼슘(Ca), 스트론튬(Sr), 바륨(Ba), 티탄(Ti), 아연(Zn), 보론(B), 니오븀(Nb), 갈륨(Ga), 인듐(In), 몰리브덴(Mo), 텅스텐(W), 알루미늄(Al), 실리콘(Si), 크롬(Cr), 바나듐(V), 스칸듐(Sc), 이트륨(Y) 또는 이들의 조합이며, X가 O, F, S, P 또는 이들의 조합이다.

[0169] <Chemical Formula 9>

[0170] Li a M3 z PO4

[0171] In the above chemical formula 9, 0.90≤a≤1.1, 0.9≤z≤1.1, and M3 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr), or a combination thereof.

[0172] The oxide-based cathode active material may be covered by a covering layer. The covering layer may be any material known as a covering layer for cathode active materials of all-solid-state secondary batteries. Examples of the covering layer include Li2O-ZrO2 (LZO).

[0173] The size of the oxide-based cathode active material may be, for example, 0.1 to 30 μm, 0.5 to 20 μm, or 1 to 15 μm. The oxide-based cathode active material may be, for example, a single-crystal particle or a polycrystalline particle.

[0174] The sulfide-based cathode active material may include, for example, a Li2S-containing composite. The Li2S-containing composite includes, for example, a composite of Li2S and carbon, a composite of Li2S, carbon, and a solid electrolyte, a composite of Li2S and a solid electrolyte, a composite of Li2S and a lithium salt, a composite of Li2S, a lithium salt, and carbon, a composite of Li2S and a metal carbide, a composite of Li2S, carbon, and a metal carbide, a composite of Li2S and a metal nitride, a composite of Li2S, carbon, and a metal nitride, or a combination thereof.

[0175] The Li2S and carbon complex comprises carbon. The carbon may be any material containing carbon atoms that is used as a conductive material in the art. The carbon may be, for example, crystalline carbon, amorphous carbon, or a combination thereof. The carbon may be, for example, a sintered product of a carbon precursor. The carbon may be, for example, a carbon nanostructure. The carbon nanostructure may be, 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 be, for example, a carbon nanotube, a carbon nanofiber, a carbon nanobelt, a carbon nanorod, graphene, graphene oxide (GO), reduced graphene oxide (rGO), graphene balls (GB), or a combination thereof. The carbon may be, for example, porous carbon or non-porous carbon. The porous carbon may include, for example, periodic and regular two-dimensional or three-dimensional pores. The porous carbon may be, for example, carbon black such as Ketjen black, acetylene black, Denka black, thermal black, channel black, etc.; graphite, activated carbon, or a combination thereof. The form of the carbon may be, for example, particle form, sheet form, fiber form, etc., but is not limited thereto, and any method used as carbon in the relevant technical field may be used. The method for preparing the composite of Li2S and carbon may be, for example, a dry method, a wet method, or a combination thereof, but is not limited thereto, and the method for preparing the composite of Li2S and carbon in the relevant technical field may be, for example, milling, heat treatment, deposition, etc., but is not necessarily limited thereto, and any method used in the relevant technical field may be used.

[0176] A composite of Li2S, carbon, and a solid electrolyte comprises carbon and a solid electrolyte. Carbon refers to the composite of Li2S and carbon described above. The solid electrolyte may be any ion-conducting material used in the art, such as an amorphous solid electrolyte. The solid electrolyte may be, for example, an inorganic solid electrolyte. The solid electrolyte may be, for example, a crystalline solid electrolyte, an amorphous solid electrolyte, or a combination thereof. The solid electrolyte may be, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a combination thereof. The sulfide-based solid electrolyte may comprise, for example, Li, S, and P, and may optionally further comprise a halogen element. The sulfide-based solid electrolyte may be selected from among the sulfide-based solid electrolytes used in the solid electrolyte layer. The sulfide-based solid electrolyte and the oxide-based solid electrolyte refer to the sulfide-based solid electrolyte and the oxide-based solid electrolyte of the solid electrolyte layer described above.

[0177] The composite of Li2S and a solid electrolyte includes a solid electrolyte. The solid electrolyte refers to the composite of Li2S, carbon, and a solid electrolyte described above.

[0178] The complex of Li2S and a lithium salt comprises a lithium salt compound. The lithium salt compound does not contain, for example, a sulfur (S) atom. The lithium salt compound can be, for example, a binary compound composed of lithium and one element selected from Groups 13 to 17 of the Periodic Table of Elements. The binary compound can include, for example, one or more selected from LiF, LiCl, LiBr, LiI, LiH, Li2S, Li2O, Li2Se, Li2Te, Li3N, Li3P, Li3As, Li3Sb, LiI3, and LiB3. The lithium salt compound can be, for example, a ternary compound composed of lithium and two elements selected from Groups 13 to 17 of the Periodic Table of Elements. The ternary compound includes, for example, one or more selected from Li3OCl, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiNO3, Li2CO3, LiBH4, Li2SO4, Li3BO3, Li3PO4, Li4NCl, Li5NCl2, and Li3BN2. The lithium salt compound is particularly one or more lithium halide compounds selected from LiF, LiCl, LiBr, and LiI. The complex of Li2S and a solid electrolyte includes a solid electrolyte. The solid electrolyte refers to the solid electrolyte used in the complex of Li2S, carbon, and a solid electrolyte described above. The complex of Li2S and the solid electrolyte includes, for example, a complex of Li2S and one or more lithium salts selected from LiF, LiCl, LiBr, LiI, LiH, Li2S, Li2O, Li2Se, Li2Te, Li3N, Li3P, Li3As, Li3Sb, LiI3 and LiB3.

[0179] The complex of Li2S and a lithium salt and carbon includes a lithium salt compound and carbon. Carbon refers to the complex of Li2S and carbon described above.

[0180] The composite of Li2S and metal carbide includes metal carbide. The metal carbide is, for example, a two-dimensional metal carbide. The two-dimensional metal carbide is, for example, MXene. The two-dimensional metal carbide is, for example, M n+1 C n T x (M is a transition metal, T is a terminal group, T is O, OH and / or F, n=1, 2, or 3, x is the number of terminal groups, x=0, 1, or 2) is expressed as. Two-dimensional metal carbides are, for example, Ti2CT. x , (Ti 0.5 , Nb 0.5 )2CT x , Nb2CT x , V2CT x , Ti3C2T x , (V 0.5 , Cr 0.5 )3C2T x , Ti3CNT x , Ta4C3T x , Nb4C3T x or a combination thereof, where x = 0, 1, or 2. The surface of the two-dimensional metal carbide is terminated with O, OH, and / or F.

[0181] The complex of Li2S, carbon, and metal carbide includes carbon and metal carbide. Carbon refers to the complex of Li2S and carbon described above. Metal carbide refers to the complex of Li2S and metal carbide described above.

[0182] The complex of Li2S and metal nitride includes a metal nitride. The metal nitride is, for example, a two-dimensional metal nitride. The two-dimensional metal nitride is, for example, M n+1 N n T x(M is a transition metal, T is a terminal group, T is O, OH and / or F, n=1, 2, or 3, x is the number of terminal groups, x=0, 1, or 2) is expressed as. The surface of the two-dimensional metal nitride is terminated with O, OH and / or F.

[0183] A complex of Li2S, carbon, and a metal nitride includes carbon and a metal nitride. Carbon refers to the complex of Li2S and carbon described above. Metal carbide refers to the complex of Li2S and a metal nitride described above.

[0184] The Li2S-containing composite may further include, for example, a second fibrous sulfide-based solid electrolyte (not shown). The Li2S-containing composite may be a composite of Li2S and the second fibrous sulfide-based solid electrolyte, or a composite of Li2S and the second fibrous sulfide-based solid electrolyte and the above-described carbon, solid electrolyte, lithium salt, metal carbide, or metal nitride.

[0185] When the Li2S-containing composite further includes a second fibrous sulfide-based solid electrolyte, the deterioration of the lithium battery can be further suppressed and the cycle characteristics of the lithium battery can be further improved. The size of the second fibrous sulfide-based solid electrolyte can be smaller than the size of the first fibrous sulfide-based solid electrolyte (100). The length and / or thickness of the second fibrous sulfide-based solid electrolyte can be 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less of the length and / or thickness of the first fibrous sulfide-based solid electrolyte (100), respectively. The length and / or thickness of the second fibrous sulfide-based solid electrolyte can be 0.1 to 50%, 0.5 to 40%, 1 to 30%, 1 to 20%, or 1 to 10% of the length and / or thickness of the first fibrous sulfide-based solid electrolyte (100), respectively. The second fibrous sulfide-based solid electrolyte may have, for example, the same shape as the first fibrous sulfide-based solid electrolyte (100) but may have a smaller size. The second fibrous sulfide-based solid electrolyte may be easily distributed within the Li2S-containing composite due to its reduced length and / or thickness. The second fibrous sulfide-based solid electrolyte may further suppress deterioration of the lithium battery and further improve cycle characteristics of the lithium battery due to its reduced length and / or thickness.

[0186] The size of the sulfide-based cathode active material can be, for example, 0.1 to 50 μm, 0.5 to 30 μm, 0.5 to 20 μm, or 1 to 10 μm. The size of Li2S can be, for example, 1 nm to 10 μm, 10 nm to 5 μm, 10 nm to 3 μm, or 10 nm to 1 μm. The size of the Li2S-containing composite can be, for example, 0.1 to 50 μm, 0.5 to 30 μm, 0.5 to 20 μm, or 1 to 10 μm.

[0187] The shape of the cathode active material is, for example, a spherical particle shape, an elliptical particle shape, etc. The particle size of the cathode active material is not particularly limited and is within the range applicable to cathode active materials of conventional all-solid-state secondary batteries.

[0188] The cathode active material may include, for example, a composite cathode active material. The composite cathode active material may include, for example, a core comprising a lithium transition metal oxide; and a shell disposed along the surface of the core. The shell may include an inorganic filler. The inorganic filler includes a lithium metal oxyhalide represented by the chemical formula 1 described above.

[0189] In the composite cathode active material, a shell containing an inorganic filler may be coated on part or all of the core. In the composite cathode active material, by disposing the inorganic filler on part or all of the lithium transition metal oxide core, an increase in the interfacial resistance between the composite cathode active material and the first solid electrolyte can be suppressed. Consequently, the internal resistance of the all-solid-state secondary battery (1) can be reduced, thereby improving the cycle characteristics of the all-solid-state secondary battery (1).

[0190] In the composite cathode active material, the inorganic filler content may be 0.1 to 20 parts by weight, 0.1 to 10 parts by weight, or 0.1 to 5 parts by weight based on 100 parts by weight of the core. When the composite cathode active material has an inorganic filler content within this range, part or all of the surface of the core may be coated with the inorganic filler. If the content of the inorganic filler coated on the core is too low, the coating effect may be minimal. If the content of the inorganic filler coated on the core is too high, the energy density of the cathode active material layer (12) may be reduced.

[0191] The above-mentioned positive electrode active material layer includes a lithium sulfide-based positive electrode active material and an inorganic filler, and the inorganic filler may contain a lithium metal oxyhalide represented by the following chemical formula 1.

[0192] <Chemical Formula 1>

[0193] Li a M b O c Cl d

[0194] In chemical formula 1, 0 <a≤3; 0<b≤3; 0<c≤3; 0<d≤8; c<d; a / (a+b+c+d)<0.5,

[0195] M is a metal selected from groups 3 to 15 of the periodic table.

[0196] The positive electrode can contain the above-described inorganic filler to suppress an increase in interfacial resistance between components constituting the composite positive electrode active material, thereby improving the charge / discharge characteristics of the all-solid-state secondary battery. The inorganic filler can have elasticity. Since the inorganic filler has elasticity, the volume change of the positive electrode active material layer containing the composite positive electrode active material can be accommodated more effectively. In addition, since the inorganic filler can be easily molded into various shapes, the pores formed in the positive electrode active material layer can be easily filled. By suppressing an increase in internal resistance due to the pores of the positive electrode active material layer containing the composite positive electrode active material, an increase in internal resistance of the all-solid-state secondary battery can be suppressed. As a result, the charge / discharge characteristics of the all-solid-state secondary battery can be improved.

[0197] By including an inorganic filler in the cathode active material layer, it can provide improved durability against potential changes and temperature changes occurring during the charge / discharge process compared to a cathode active material layer including an organic filler. Inorganic fillers can suppress deterioration during the charge / discharge process of an all-solid-state secondary battery compared to organic fillers. Consequently, the charge / discharge characteristics of the all-solid-state secondary battery can be improved.

[0198] The application of a cathode active material layer containing inorganic fillers enhances the electronic and ionic networks of the lithium sulfide-based cathode active material and the solid electrolyte, enabling increased capacity, cycle life, and low-voltage operation, while improving high-voltage cathode side reactions. All-solid-state secondary batteries employing such a cathode active material layer can improve specific capacity and initial efficiency, for example, by reducing capacity degradation above 1.5 V or between 1.0 and 1.5 V. In particular, the infiltration characteristics with the argyrodite solid electrolyte layer reduce dendrite formation at high output and cracking in the cathode active material layer, thereby improving the cycle life characteristics of the all-solid-state secondary battery. In addition, when configuring a cathode with a thick film that realizes high energy density, the rate characteristic degradation is improved, reducing the occurrence of short circuits during rapid charging, and the short circuit phenomenon is reduced due to the reduction of pinholes in the solid electrolyte layer. Therefore, the elastic sheet ratio can be reduced, so that the cell clamping pressure can be lowered to 2.5 M or less, 2 MPa or less, 0.1 to 2 MPa, or 0.15 to 1 MPa, thereby enabling the implementation of a free-standing cell.

[0199] [Cathode active material layer: first solid electrolyte]

[0200] Referring to FIGS. 1 to 12, the positive electrode active material layer (12) includes a first solid electrolyte. The first solid electrolyte included in the positive electrode active material layer (12) may be the same as or different from the solid electrolyte included in the solid electrolyte layer (30).

[0201] The first solid electrolyte included in the positive electrode active material layer (12) may have a smaller average D50 particle diameter than the solid electrolyte included in the solid electrolyte layer (30). For example, the average D50 particle diameter of the first solid electrolyte included in the positive electrode active material layer (12) may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the average D50 particle diameter of the solid electrolyte included in the solid electrolyte layer (30). The average D50 particle diameter is, for example, a median particle diameter (D50). The median particle diameter (D50) is, for example, the size of particles corresponding to 50% of the cumulative volume, calculated from the side of particles having a small particle size in a size distribution of particles measured by laser diffraction.

[0202] The content of the first solid electrolyte included in the positive electrode active material layer (12) may be, for example, 1 wt% to 40 wt%, 1 wt% to 30 wt%, 1 wt% to 20 wt%, or 1 wt% to 10 wt% of the total weight of the positive electrode active material layer (12).

[0203] The first solid electrolyte may be, for example, a sulfide-based solid electrolyte. The sulfide-based solid electrolyte may include, for example, an argyrodite-type solid electrolyte represented by the following chemical formula 10:

[0204] <Chemical Formula 10>

[0205] Li + 12-n-x A n+ X 2- 6-x Y - x

[0206] In the above chemical formula 10, A is P, As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb or Ta, X is S, Se or Te, Y is Cl, Br, I, F, CN, OCN, SCN or N3, and 1≤n≤5, 0≤x≤2. The sulfide-based solid electrolyte 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 , may be an argyrodite-type compound including at least one selected from 0≤x≤2. The sulfide-based solid electrolyte may be, for example, an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0207] The density of the argyrodite-type solid electrolyte may be 1.5 to 2.0 g / cc. Since the argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state secondary battery is reduced, and penetration of the solid electrolyte layer by Li can be effectively suppressed.

[0208] [Cathode active material layer: inorganic filler]

[0209] Referring to FIGS. 1 to 10, the cathode active material layer (12) may further include an inorganic filler. The inorganic filler may be Li a Al b M c O d Cl e(0 <a≤3; 0<b≤3; 0≤c<2; 0<d≤2; 0<e≤4; d<e, M은 원소주기율표 3족 내지 15족에서 선택되는 금속) 표시되는 리튬금속옥시할라이드(lithium metal oxyhalide)를 포함한다.

[0210] The content of the inorganic filler included in the positive electrode active material layer (12) may be, for example, 0.1 to 20 wt%, 0.1 to 10 wt%, or 0.1 to 5 wt% of the total weight of the positive electrode active material layer (12).

[0211] The inorganic filler included in the cathode active material layer (12) may be selected from among the inorganic fillers used in the solid electrolyte layer (30). For specific details regarding the inorganic filler, refer to the solid electrolyte layer (30) described above.

[0212] The weight ratio of the first solid electrolyte and the inorganic filler in the positive electrode active material layer (12) may be, for example, 99:1 to 1:99, 90:1 to 10:90, 80:20 to 20:80, 70:30 to 30:70, or 60:40 to 40:60. When the first solid electrolyte and the inorganic filler have a weight ratio within this range, the all-solid-state secondary battery (1) can provide excellent cycle characteristics.

[0213] The content of the inorganic filler in the positive electrode active material layer (12) may be, for example, smaller than the content of the first solid electrolyte. The weight ratio of the first solid electrolyte and the inorganic filler in the positive electrode active material layer (12) may be 99:1 to 50:50, 99:1 to 60:40, 99:1 to 70:30, 99:1 to 80:20, or 99:1 to 90:10. Since the first solid electrolyte and the inorganic filler have a weight ratio within this range, the volume change during charge and discharge of the positive electrode active material layer (12) can be more easily accommodated. As a result, the cycle characteristics of the all-solid-state secondary battery (1) can be further improved.

[0214] [Cathode active material layer: conductive material]

[0215] The cathode active material layer (12) may further include a conductive material. The conductive material may be, for example, a carbon-based material, a metal-based material, or a combination thereof.

[0216] The conductive material content included in the positive electrode active material layer (12) may be, for example, 1 wt% to 30 wt%, 1 wt% to 20 wt%, or 1 wt% to 10 wt% of the total weight of the positive electrode active material layer (12).

[0217] The metal-based material may be, but is not limited to, metal powder, metal fiber, or a combination thereof, and any metal-based material used as a conductive material in the relevant technical field may be used.

[0218] The carbon-based material may include, for example, amorphous carbon. By including amorphous carbon in the carbon-based material, side reactions between the carbon-based material and the first solid electrolyte can be suppressed. Accordingly, the cycle characteristics of the all-solid-state secondary battery (1) including the carbon-based material can be further improved.

[0219] The carbon-based material may be, for example, a sintered product of a carbon precursor. The carbon-based material may be, for example, a carbon nanostructure. The carbon nanostructure may be, for example, a one-dimensional carbon nanostructure, a two-dimensional carbon nanostructure, a three-dimensional carbon nanostructure, or a combination thereof. As used herein, a one-dimensional carbon nanostructure is a carbon nanostructure in which one dimension is significantly larger than the other two dimensions. In other words, a one-dimensional carbon nanostructure in which the length defined in one dimension is significantly larger than the other two dimensions. For example, the one-dimensional carbon nanostructure may be, but is not limited to, one or more selected from carbon nanotubes, carbon nanowires, carbon nanofibers, carbon nanobelts, carbon nanorods, and combinations thereof, and any one that can be used as a one-dimensional carbon nanostructure in the art may be used. Carbon nanotubes include, but are not necessarily limited to, single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs), and any carbon nanotube that can be used in the relevant technical field may be used. In the present specification, a two-dimensional carbon nanostructure is a carbon nanostructure in which two dimensions are significantly larger than the other dimension. In other words, it is a carbon nanostructure in which an area defined by two dimensions is significantly larger than a thickness. For example, the two-dimensional carbon nanostructure may be at least one selected from graphene oxide, reduced graphene oxide, graphene nanoplatelets, carbon nanosheets, and combinations thereof, but is not necessarily limited to these, and any carbon nanostructure that can be used in the relevant technical field may be used.

[0220] The carbon nanostructure may be, for example, carbon nanotubes, carbon nanofibers, carbon nanobelts, carbon nanorods, graphene, or a combination thereof. The carbon-based material 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 be, for example, carbon black such as Ketjen black, acetylene black, Denka black, thermal black, channel black, or the like; graphite, activated carbon, or a combination thereof. The form of the carbon-based material may be, for example, particle form, sheet form, flake form, or the like, but is not limited thereto, and any form that can be used as a carbon-based material in the art may be used.

[0221] The carbon-based material may include, for example, a fibrous carbon-based material. By including the fibrous carbon-based material in the composite, the electronic conductivity of the composite may be further improved. By including the fibrous carbon-based material in the composite, electronic conduction may be more easily performed from the surface to the interior of the composite. The internal resistance of a composite cathode active material including the composite may be reduced, and the cycle characteristics of a secondary battery including the composite cathode active material may be further improved. 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. When the fibrous carbon-based material has an aspect ratio in 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. The fibrous carbon-based material may include, for example, a carbon nanostructure. The carbon nanostructure may include, for example, a carbon nanofiber (CNF), a carbon nanotube (CNT), a carbon nanobelt, a carbon nanorod, or a combination thereof. The carbon nanostructure may form a primary carbon nanostructure composed of a single carbon nanostructure, and a secondary carbon nanostructure in which a plurality of carbon nanostructures are aggregated.

[0222] The diameter of the primary carbon nanostructure can be, for example, 1 nm to 200 nm, 1 nm to 150 nm, 1 nm to 100 nm, 1 nm to 50 nm, 1 nm to 30 nm, or 1 nm to 20 nm. The length of the primary carbon nanostructure can be, for example, 10 nm to 2 μm, 10 nm to 1.5 μm, 10 nm to 1 μm, 10 nm to 500 nm, 10 nm to 400 nm, 10 nm to 300 nm, 10 nm to 200 nm, or 10 nm to 100 nm. The diameter and length of the primary carbon nanostructure can be measured from scanning electron microscope (SEM) or transmission electron microscope (TEM) images. Alternatively, the diameter and / or length of the primary carbon nanostructure can be measured by laser diffraction.

[0223] Secondary carbon nanostructures are, for example, structures formed by assembling primary carbon nanostructures in whole or in part to form bundles or bundle-type structures. The secondary carbon nanostructures may include, for example, bundle-type carbon nanostructures, rope-type carbon nanostructures, or combinations thereof. The diameter of the secondary carbon nanostructures may be, for example, 2 nm to 200 nm, 3 nm to 150 nm, 5 nm to 100 nm, 5 nm to 50 nm, 5 nm to 30 nm, or 5 nm to 20 nm. The length of the secondary carbon nanotube structure can be, for example, 20 nm to 2 ㎛, 30 nm to 1.5 ㎛, 50 nm to 1 ㎛, 50 nm to 500 nm, 50 nm to 400 nm, 50 nm to 300 nm, 50 nm to 200 nm, or 50 nm to 100 nm or more. The diameter and length of the secondary carbon nanostructure can be measured from a scanning electron microscope (SEM) image or an optical microscope. Alternatively, the diameter and / or length of the secondary carbon nanostructure can be measured by laser diffraction. The secondary carbon nanostructure can be converted into the primary carbon nanostructure by, for example, dispersing it in a solvent or the like and then used in the preparation of a composite.

[0224] [Cathode active material layer: binder]

[0225] The positive electrode active material layer (12) may further include a binder. The binder may be, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited thereto, and any binder used in the relevant technical field may be used. The binder content included in the positive electrode active material layer (12) 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 positive electrode active material layer (12). The binder may be omitted.

[0226] [Cathode active material layer: other additives]

[0227] The cathode active material layer (12) may further include additives such as fillers, coating agents, dispersants, and ion conductive aids in addition to the cathode active material, solid electrolyte, binder, and conductive agent described above.

[0228] As fillers, coating agents, dispersants, ion conductivity aids, etc. that the positive electrode active material layer (12) may include, known materials generally used in electrodes of all-solid-state secondary batteries may be used.

[0229] [interlayer]

[0230] Referring to FIGS. 2, 4, 6, 8 and 10, the positive electrode (10) further includes an interlayer (13) disposed between the positive electrode current collector (11) and the positive electrode active material layer (12).

[0231] The intermediate layer (13) is, for example, directly disposed on one side or both sides of the positive electrode collector (11). No other layer may be disposed between the positive electrode collector (11) and the intermediate layer (13). By directly disposing the intermediate layer (13) on one side or both sides of the positive electrode collector (11), the bonding force between the positive electrode collector (11) and the positive electrode active material layer (12) can be further improved. By disposing the intermediate layer (13) between the positive electrode collector (11) and the positive electrode active material layer (12), side reactions between the inorganic filler and / or the first solid electrolyte and the positive electrode collector (11) can be more effectively suppressed. Therefore, deterioration of the all-solid-state secondary battery (1) during the charge / discharge process can be suppressed, and the cycle characteristics of the all-solid-state secondary battery (1) can be further improved.

[0232] The thickness of the intermediate layer (13) is, for example, 0.01 to 20%, 0.1 to 20%, 0.5 to 20%, 1 to 20%, 1 to 15%, 1 to 10%, 2 to 8%, or 3 to 7% of the thickness of the positive electrode current collector (11). The thickness of the intermediate layer (13) is, for example, 10 nm to 5 ㎛, 50 nm to 5 ㎛, 200 nm to 4 ㎛, 500 nm to 3 ㎛, 500 nm to 2 ㎛, 500 nm to 1.5 ㎛, or 700 nm to 1.3 ㎛. When the intermediate layer (13) has a thickness in this range, the bonding force between the positive electrode current collector (11) and the positive electrode active material layer (12) is further improved, and an increase in interface resistance is suppressed. The thickness of the intermediate layer can be measured, for example, from a scanning electron microscope (SEM) image of a cross-section of the intermediate layer.

[0233] The intermediate layer (13) includes, for example, a carbon-based conductive material. The carbon-based conductive material included in the intermediate layer (13) may be selected from among the carbon-based conductive materials used in the positive electrode active material layer (12). The intermediate layer (13) may include the same carbon-based conductive material as the carbon-based conductive material used in the positive electrode active material layer (12). Since the intermediate layer (13) includes a carbon-based conductive material, the intermediate layer (13) may be, for example, a conductive layer.

[0234] The intermediate layer (13) may additionally include, for example, a binder. By additionally including a binder in the intermediate layer (13), the bonding strength between the positive electrode current collector (11) and the positive electrode active material layer (12) may be further improved. The binder included in the intermediate layer (13) may be, for example, a conductive binder or a non-conductive binder. The conductive binder may be, for example, an ion-conductive binder and / or an electron-conductive binder. A binder having both ion-conductive and electron-conductive properties may belong to both an ion-conductive binder and an electron-conductive binder.

[0235] The binder included in the intermediate layer (13) may be selected from among the binders used in the positive electrode active material layer (12). The intermediate layer (13) may include the same binder as the binder used in the positive electrode active material layer (12). The binder included in the intermediate layer (13) is, for example, a fluorinated binder. The fluorinated binder included in the intermediate layer (13) is, for example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or a combination thereof. The intermediate layer (13) may be, for example, a bonding layer including a binder. The intermediate layer (13) may be, for example, a conductive layer including a binder and a carbon-based conductive material.

[0236] The intermediate layer (13) can be disposed on the positive electrode collector (11) in a dry or wet manner, for example. The intermediate layer (13) can be disposed on the positive electrode collector (11) in a dry manner, for example, by deposition such as CVD or PVD. The intermediate layer (13) can be disposed on the positive electrode collector (11) in a wet manner, for example, by spin coating, dip coating, or the like. The intermediate layer (13) can be disposed on the positive electrode collector (11) in a dry manner, for example, by depositing a carbon-based conductive material on a substrate by deposition. The dry-coated intermediate layer (13) is made of a carbon-based conductive material and may not include a binder. The intermediate layer (13) can be disposed on the positive electrode collector (11) in a dry manner, for example, by coating a composition including a carbon-based conductive material, a binder, and a solvent on the surface of the electrode collector and drying it. The intermediate layer (13) can have a single-layer structure or a multi-layer structure including a plurality of layers. Multi-layer structures can be two-layer, three-layer, four-layer, etc.

[0237] Referring to FIGS. 1 to 3, 5, 7, 9, and 10, the positive electrode (10) may have a positive electrode active material layer (12) directly disposed on the positive electrode current collector (11). Another layer, for example, an intermediate layer, may not be disposed between the positive electrode current collector (11) and the positive electrode active material layer (12).

[0238] In the positive electrode layer (10) in which the positive electrode active material layer (12) is directly disposed on the positive electrode current collector (11), the positive electrode current collector (11) may be inactive with respect to the inorganic filler. The positive electrode current collector (11) may not cause a side reaction with the inorganic filler. The positive electrode current collector (11) may include, for example, tungsten (W).

[0239] [Anode current collector]

[0240] Referring to FIGS. 1 to 10, the positive electrode layer (10) includes a positive electrode current collector (11).

[0241] The positive electrode collector (11) uses a plate or foil made of, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. The positive electrode collector (11) may be omitted. The thickness of the positive electrode collector (11) is, for example, 1 µm to 100 µm, 1 µm to 50 µm, 5 µm to 25 µm, or 10 µm to 20 µm.

[0242] The cathode current collector (11) may include, for example, a base film and a metal layer disposed on one or both sides of the base film. The base film may include, for example, a polymer. The polymer may be, for example, a thermoplastic polymer. The polymer may include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. The base film may be, for example, an insulator. Since the base film includes an insulating thermoplastic polymer, when a short circuit occurs, the base film softens or liquefies, thereby blocking battery operation and suppressing a rapid increase in current. The metal layer may include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), or an alloy thereof. The metal layer can act as an electrochemical fuse and be cut off in case of overcurrent to prevent a short circuit. The limit current and the maximum current can be controlled by adjusting the thickness of the metal layer. The metal layer can be plated or deposited on the base film. As the thickness of the metal layer decreases, the limit current and / or the maximum current of the positive electrode current collector (11) decreases, thereby improving the stability of the lithium battery in case of a short circuit. A lead tab can be added on the metal layer for connection to the outside. The lead tab can be welded to the metal layer or the metal layer / base film laminate by ultrasonic welding, laser welding, spot welding, etc. During welding, the base film and / or the metal layer melt, so that the metal layer can be electrically connected to the lead tab. In order to strengthen the welding of the metal layer and the lead tab, a metal chip can be added between the metal layer and the lead tab.The metal piece may be a thin piece of the same material as the metal of the metal layer. The metal piece may be, for example, a metal foil, a metal mesh, etc. The metal piece may be, for example, aluminum foil, copper foil, SUS foil, etc. After the metal piece is placed on the metal layer, the lead tab may be welded to the metal piece / metal layer laminate or the metal piece / metal layer / base film laminate. During welding, the base film, the metal layer, and / or the metal piece may melt, so that the metal layer or the metal layer / metal piece laminate may be electrically connected to the lead tab. A metal chip and / or a lead tab may be added to a portion of the metal layer. The base film may have a thickness of, for example, 1 to 50 μm, 1.5 to 50 μm, 1.5 to 40 μm, or 1 to 30 μm. When the base film has a thickness in this range, the weight of the electrode assembly can be more effectively reduced. The melting point of the base film may be, for example, 100 to 300°C, 100 to 250°C or less, or 100 to 200°C. Since the base film has a melting point within this range, the base film can be melted and easily bonded to the lead tab during the welding process of the lead tab. To improve the adhesion between the base film and the metal layer, a surface treatment such as corona treatment may be performed on the base film. The thickness of the metal layer may be, for example, 0.01 to 3 μm, 0.1 to 3 μm, 0.1 to 2 μm, or 0.1 to μm. Since the metal layer has a thickness within this range, conductivity can be maintained while ensuring the stability of the electrode assembly. The thickness of the metal piece may be, for example, 2 to 10 μm, 2 to 7 μm, or 4 to 6 μm. Since the metal piece has a thickness within this range, the connection between the metal layer and the lead tab can be performed more easily. By having this structure, the positive electrode current collector (11) can reduce the weight of the positive electrode and consequently improve the energy density of the positive electrode and the all-solid-state secondary battery.

[0243] [Inert Absence]

[0244] Referring to FIGS. 1 to 10, the positive electrode (10) includes a positive electrode current collector (11), a positive electrode active material layer (12) disposed on one surface of the positive electrode current collector. Referring to FIGS. 8 and 10, the positive electrode (10) includes a positive electrode current collector (11), a positive electrode active material layer (12) disposed on one surface of the positive electrode current collector, and an intermediate layer (13) disposed between the positive electrode current collector (11) and the positive electrode active material layer (13). An inactive member (40) is disposed on one side of the positive electrode (10). Referring to FIGS. 7 and 8, the inactive member (40) is disposed on one side of the positive electrode active material layer (12) and the positive electrode current collector (11). Referring to FIGS. 9 and 10, the inert member (40) is disposed on one side of the positive electrode active material layer (12) and is disposed between the electrolyte layer (30) and the positive electrode current collector (11) facing the electrolyte layer (30). The inert member (40) is not disposed on one side of the positive electrode current collector (11). The electrolyte layer (30) may be, for example, a solid electrolyte layer.

[0245] By including an inert member (40), cracking of the electrolyte layer (30) is prevented during the manufacture and / or charging / discharging of the all-solid-state secondary battery (1), and as a result, the cycle characteristics of the all-solid-state secondary battery (2) are improved. In an all-solid-state secondary battery (1) that does not include an inert member (40), when the manufacture and / or charging / discharging of the all-solid-state secondary battery (1) is performed, uneven pressure is applied to the electrolyte layer (30) in contact with the positive electrode (10), which increases the possibility of cracking in the electrolyte layer (30), and thus, a short circuit may occur due to the growth of lithium metal through the crack.

[0246] In the all-solid-state secondary battery (1), the thickness of the inert member (40) is greater than or equal to the thickness of the positive electrode active material layer (12). Alternatively, in the all-solid-state secondary battery (1), the thickness of the inert member (40) is substantially equal to the thickness of the positive electrode (10). Since the thickness of the inert member (40) is equal to the thickness of the positive electrode (10), a uniform pressure is applied between the positive electrode (10) and the electrolyte layer (30), and the positive electrode (10) and the electrolyte layer (30) are sufficiently adhered to each other, so that the interfacial resistance between the positive electrode (10) and the electrolyte layer (30) can be reduced. In addition, since the electrolyte layer (30) is sufficiently sintered during the pressurized manufacturing process of the all-solid-state secondary battery (1), the internal resistance of the electrolyte layer (30) and the all-solid-state secondary battery (1) including the same is reduced.

[0247] The inert member (40) surrounds the side surface of the positive electrode (10) and is in contact with the electrolyte layer (30). By the inert member (40) surrounding the side surface of the positive electrode (10) and being in contact with the electrolyte layer (30), cracks in the electrolyte layer (30) that occur due to a pressure difference during the pressing process in the electrolyte layer (30) that does not come into contact with the positive electrode (20) can be effectively suppressed. The inert member (40) surrounds the side surface of the positive electrode (10) and is separated from the negative electrode (20), more specifically, the first negative electrode active material layer (22). The inert member (40) surrounds the side surface of the positive electrode (10), is in contact with the electrolyte layer (30), and is separated from the negative electrode (20). Therefore, the possibility of a short circuit occurring due to physical contact between the positive electrode (10) and the first negative electrode active material layer (22) or a short circuit occurring due to overcharging of lithium, etc., is suppressed. For example, by placing an inert member (40) on one side of the positive electrode active material layer (12) and simultaneously on one side of the positive electrode current collector (11), the possibility of a short circuit occurring due to contact between the positive electrode current collector (11) and the negative electrode (20) is more effectively suppressed.

[0248] Referring to FIGS. 7 to 10, the inert member (40) extends from one side of the positive electrode (30) to the end of the electrolyte layer (30). By extending the inert member (40) to the end of the electrolyte layer (30), cracks occurring at the end of the electrolyte layer (30) can be suppressed. The end of the electrolyte layer (30) is the outermost part that is in contact with the side of the electrolyte layer (30). The inert member (40) extends to the outermost part that is in contact with the side of the electrolyte layer (30). The inert member (40) is separated from the negative electrode (20), more specifically, from the first negative electrode active material layer (22). The inert member (40) extends to the end of the electrolyte layer (30), but does not contact the negative electrode (20). The inert member (40) fills a space extending from, for example, one side of the anode (30) to the end of the electrolyte layer (30).

[0249] Referring to FIGS. 7 to 10, the width of the inert member (40) extending from one side of the positive electrode (10) to the end of the electrolyte layer (30) is, for example, 1 to 30%, 1 to 25%, 1 to 20%, 1 to 15%, 1 to 10%, or 1 to 5% of the width between one side of the positive electrode (10) and the other side opposite to the one side. If the width of the inert member (40) is excessively large, the energy density of the all-solid-state secondary battery (1) is reduced. If the width of the inert member (40) is excessively small, the effect of arranging the inert member (40) is minimal.

[0250] The area of ​​the anode (10) is smaller than the area of ​​the electrolyte layer (30) in contact with the anode (10). An inert member (40) is arranged to surround the side of the anode (10) to compensate for the area difference between the anode (10) and the electrolyte layer (30). By compensating for the difference between the area of ​​the anode (10) and the area of ​​the electrolyte layer (30), cracks in the electrolyte layer (30) caused by the pressure difference during the pressing process are effectively suppressed. For example, the sum of the area of ​​the anode (10) and the area of ​​the inert member (40) is equal to the area of ​​the electrolyte layer (30). The electrolyte layer (30) may be, for example, a solid electrolyte layer.

[0251] The area of ​​the anode (10) is, for example, less than 100%, 99% or less, 98% or less, 97% or less, 96% or less, or 95% or less of the area of ​​the electrolyte layer (30). The area of ​​the anode (10) is, for example, 50% to less than 100%, 50% to 99%, 55% to 98%, 60% to 97%, 70% to 96%, 80% to 95%, or 85% to 95% of the area of ​​the electrolyte layer (30).

[0252] If the area of ​​the positive electrode (10) is equal to or larger than the area of ​​the electrolyte layer (30), the possibility of a short circuit occurring due to physical contact between the positive electrode (10) and the first negative electrode active material layer (22) or overcharging of lithium increases. The area of ​​the positive electrode (10) is, for example, equal to the area of ​​the positive electrode active material layer (12). The area of ​​the positive electrode (10) is, for example, equal to the area (11) of the positive electrode current collector.

[0253] The area of ​​the inert member (40) is, for example, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less of the area of ​​the anode (10). The area of ​​the inert member (40) is, for example, 1% to 50%, 5% to 40%, 5% to 30%, 5% to 20%, or 5% to 15% of the area of ​​the anode (10).

[0254] The area of ​​the positive electrode (10) is smaller than the area of ​​the negative electrode current collector (21). The area of ​​the positive electrode (10) is, for example, less than 100%, 99% or less, 98% or less, 97% or less, 96% or less, or 95% or less of the area of ​​the negative electrode current collector (21). The area of ​​the positive electrode (10) is, for example, 50% to less than 100%, 50% to 99%, 55% to 98%, 60% to 97%, 70% to 96%, 80% to 95%, or 85% to 95% of the area of ​​the negative electrode current collector (21). The area of ​​the negative electrode current collector (21) is, for example, the same as the area of ​​the negative electrode (20). The area of ​​the negative electrode current collector (21) is, for example, the same as the area of ​​the first negative electrode active material layer (22).

[0255] As used herein, “same” area, length, width, thickness, and / or shape includes all instances of having “substantially the same” area, length, width, thickness, and / or shape, except where the area, length, width, thickness, and / or shape are intentionally different from each other. “Same” area, length, width, and / or thickness includes a range where the unintentional difference in the area, length, width, and / or thickness of the compared objects is, for example, less than 3%, less than 2%, less than 1%, less than 0.5%, or less than 0.1%.

[0256] The thickness of the inert member (40) is, for example, greater than the thickness of the first negative electrode active material layer (22). The thickness of the first negative electrode active material layer (22) is, for example, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less of the thickness of the inert member (40). The thickness of the first negative electrode active material layer (22) is, for example, 1% to 50%, 1% to 40%, 1% to 30%, 1% to 20%, or 1% to 10% of the thickness of the inert member (40).

[0257] The inert member (40) may be a gasket. By using a gasket as the inert member (40), cracks in the electrolyte layer (30) caused by a pressure difference during the pressing process can be effectively suppressed.

[0258] The inert member (40) has, for example, a single-layer structure. Alternatively, although not shown in the drawing, the inert member (40) may have a multi-layer structure. In the inert member (40) having a multi-layer structure, each layer may have a different composition. The inert member having a multi-layer structure may have, for example, a two-layer structure, a three-layer structure, a four-layer structure, or a five-layer structure. The inert member (40) having a multi-layer structure may include, for example, one or more adhesive layers and one or more support layers. The adhesive layer effectively prevents, for example, a separation between the positive electrode (10) and the electrolyte layer (30) due to a change in the volume of the positive electrode (10) that occurs during the charge / discharge process of the all-solid-state secondary battery (10), and improves the film strength of the inert member (40) by providing a bonding force between the support layer and other layers. The support layer provides support to the inert member (40), prevents unevenness of pressure applied to the electrolyte layer (30) during the pressurization process or the charge / discharge process, and prevents deformation of the all-solid-state secondary battery (1) being manufactured.

[0259] The inert member (40) is, for example, a flame-retardant inert member. The flame-retardant inert member can prevent thermal runaway and ignition of the all-solid-state secondary battery (1) by providing flame retardancy. Consequently, the safety of the all-solid-state secondary battery (1) is further improved. The flame-retardant inert member prevents deterioration of the all-solid-state secondary battery (1) by absorbing residual moisture within the all-solid-state secondary battery (1), thereby improving the lifespan characteristics of the all-solid-state secondary battery (1). The flame-retardant inert member may include a matrix and an additive.

[0260] The inert member (40) is a member that does not contain an electrochemically active material, for example, an electrode active material. The electrode active material is a material that absorbs / releases lithium. The inert member (40) is a member made of a material other than the electrode active material and used in the relevant technical field.

[0261] [Cathode layer]

[0262] [First negative electrode active material layer: negative electrode active material]

[0263] Referring to FIGS. 1 to 10, the negative electrode (20) includes a first negative electrode active material layer (22). The first negative electrode active material layer (22) includes, for example, a negative electrode active material and a binder.

[0264] The negative electrode active material included in the first negative electrode active material layer (22) is, for example, a negative electrode material that can form an alloy or compound with lithium.

[0265] The negative electrode active material included in the first negative electrode active material layer (22) has, for example, a particle form. The average particle diameter of the negative electrode active material having a particle form is, for example, 4 ㎛ or less, 3 ㎛ or less, 2 ㎛ or less, 1 ㎛ or less, 500 nm or less, 300 nm or less, or 100 nm or less. The average particle diameter of the negative electrode active material having a particle form is, for example, 10 nm to 4 ㎛, 10 nm to 3 ㎛, 10 nm to 2 ㎛, 10 nm to 1 ㎛, 10 nm to 500 nm, 10 nm to 300 nm, or 10 nm to 100 nm. When the negative electrode active material has an average particle diameter in this range, reversible absorption and / or desorption of lithium can be facilitated during charge and discharge. The average particle size of the negative electrode active material is, for example, the median diameter (D50) measured using a laser particle size distribution meter.

[0266] The negative electrode active material included in the first negative electrode active material layer (22) includes, for example, at least one selected from among a carbon-based negative electrode active material and a metal or semi-metal negative electrode active material.

[0267] Carbon-based negative electrode materials include, for example, amorphous carbon, crystalline carbon, porous carbon, or a combination thereof.

[0268] The carbon-based negative electrode material is, in particular, amorphous carbon. Amorphous carbon includes, but is not limited to, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), and graphene, and any material classified as amorphous carbon in the relevant technical field is acceptable. Amorphous carbon is carbon that has no crystallinity or very low crystallinity, and is distinguished from crystalline carbon or graphite-based carbon.

[0269] The carbon-based negative electrode active material may be, for example, porous carbon. The porous carbon has a pore volume of, 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 porous carbon has an average pore diameter of, for example, 1 nm to 50 nm, 1 nm to 30 nm, or 1 nm to 10 nm. The porous carbon has a BET surface area of, for example, 100 m 2 / g to 3000 m 2 / g is.

[0270] The metal or metalloid negative electrode active material includes, but is not limited to, one or more 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), and any metal or metalloid negative electrode active material that forms an alloy or compound with lithium in the relevant technical field may be used. For example, nickel (Ni) does not form an alloy with lithium and therefore is not a metal negative electrode active material.

[0271] The first negative electrode active material layer (22) includes a type of negative electrode active material among these negative electrode active materials, or includes a mixture of a plurality of different negative electrode active materials. For example, the first negative electrode active material layer (22) includes only amorphous carbon, or includes at least one 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). Alternatively, the first negative electrode active material layer (22) includes a mixture of amorphous carbon and at least one 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). The mixing ratio of the mixture of amorphous carbon and gold, etc., is a weight ratio, for example, 99:1 to 1:99, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1, but is not necessarily limited to this range and is selected according to the required characteristics of the all-solid-state secondary battery (1). When the negative electrode active material has this composition, the cycle characteristics of the all-solid-state secondary battery (1) are further improved.

[0272] The negative electrode active material included in the first negative electrode active material layer (22) includes, for example, a mixture of first particles made of amorphous carbon and second particles made of a metal or a metalloid. The metal or metalloid includes, for example, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Alternatively, the metalloid is a semiconductor. The content of the second particles is 1 to 99 wt%, 1 to 60 wt%, 8 to 60 wt%, 10 to 50 wt%, 15 to 40 wt%, or 20 to 30 wt% based on the total weight of the mixture. When the second particles have a content in this range, the cycle characteristics of, for example, an all-solid-state secondary battery (1) are further improved.

[0273] Alternatively, the first negative electrode active material layer (22) includes a composite negative electrode active material. The composite negative electrode active material may include, for example, a carbon-based support and a metal-based negative electrode active material supported on the carbon-based support. Since the composite negative electrode active material has such a structure, the metal-based negative electrode active material can be prevented from being localized within the first negative electrode active material layer and a uniform distribution can be achieved. As a result, the cycle characteristics of the all-solid-state secondary battery (1) including the first negative electrode active material layer (22) are further improved.

[0274] The metal-based negative electrode active material supported on the carbon-based support includes, for example, a metal, a metal oxide, a composite of a metal and a metal oxide, or a combination thereof. The metal includes, 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 includes, 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 includes, 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 x O y (0 <x≤1, 0<y≤2), Ag x O y (0 <x≤2, 0<y≤1), Al x O y (0 <x≤2, 0<y≤3), Bi x O y (0 <x≤2, 0<y≤3), Sn x O y (0 <x≤1, 0<y≤2), Te x O y(0 <x≤1, 0<y≤3), Zn x The y (0 <x≤1, 0<y≤1) 또는 이들의 조합을 포함할 수 있다. 금속과 금속산화물의 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.

[0275] The carbonaceous support is, for example, amorphous carbon. Amorphous carbon includes, but is not limited to, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), graphene, activated carbon, carbon nanofibers (CNF), carbon nanotubes (CNT), etc., and any material classified as amorphous carbon in the relevant technical field is possible. Amorphous carbon is carbon that has no crystallinity or very low crystallinity, and is distinguished from crystalline carbon or graphite carbon. Carbonaceous materials are, for example, carbonaceous negative electrode active materials.

[0276] The composite negative electrode active material may have, for example, a particle form. The particle size of the composite negative electrode active material having a particle form is, for example, 10 nm to 4 ㎛, 10 nm to 1 ㎛, 10 nm to 500 nm, 10 nm to 200 nm, or 10 nm to 100 nm. When the composite negative electrode active material has a particle size in this range, reversible absorption and / or desorption of lithium may be facilitated during charge and discharge. The metal-based negative electrode active material supported on the support may have, for example, a particle form. The particle size of the metal-based negative electrode active material may be, for example, 1 nm to 200 nm, 1 nm to 150 nm, 5 nm to 100 nm, or 10 nm to 50 nm. The carbon-based support may have, for example, a particle form. The particle size of the carbon-based support may be, for example, 10 nm to 2 ㎛, 10 nm to 1 ㎛, 10 nm to 500 nm, 10 nm to 200 nm, or 10 nm to 100 nm. By having a particle size in this range, the carbon-based support can be more uniformly arranged within the first negative electrode active material layer. The carbon-based support may be, for example, nanoparticles having a particle size of 500 nm or less. The particle sizes of the composite negative electrode active material, the particle sizes of the metal-based negative electrode active material, and the particle sizes of the carbon-based support are, for example, average particle sizes. The average particle size is, for example, the median diameter (D50) measured using a laser particle size distribution analyzer. Alternatively, the average particle size may be determined automatically using software, for example, from an electron microscope image, or manually by a manual method.

[0277] [First negative electrode active material layer: binder]

[0278] The first negative electrode active material layer (22) includes a binder. The binder 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 thereto and any binder used in the relevant technical field may be used. The binder may be composed of a single binder or a plurality of different binders.

[0279] Since the first negative electrode active material layer (22) includes a binder, the first negative electrode active material layer (22) is stabilized on the negative electrode current collector (21). In addition, cracking of the first negative electrode active material layer (22) is suppressed despite changes in the volume and / or relative position of the first negative electrode active material layer (22) during the charge and discharge process. For example, if the first negative electrode active material layer (22) does not include a binder, the first negative electrode active material layer (22) can be easily separated from the negative electrode current collector (21). As the first negative electrode active material layer (22) is separated from the negative electrode current collector (21), the possibility of a short circuit occurring increases as the negative electrode current collector (21) comes into contact with the electrolyte layer (30) at the exposed portion of the negative electrode current collector (21). The first negative electrode active material layer (22) is manufactured by, for example, applying a slurry in which the material constituting the first negative electrode active material layer (22) is dispersed onto the negative electrode current collector (21) and drying the slurry. By including a binder in the first negative electrode active material layer (22), stable dispersion of the negative electrode active material in the slurry is possible. For example, when applying the slurry onto the negative electrode current collector (21) by screen printing, it is possible to suppress clogging of the screen (for example, clogging by aggregates of the negative electrode active material).

[0280] [First negative electrode active material layer: other additives]

[0281] The first negative electrode active material layer (22) may further include additives used in conventional all-solid-state secondary batteries (1), such as fillers, coating agents, dispersants, and ion conductive aids.

[0282] [First negative electrode active material layer: solid electrolyte]

[0283] The first negative electrode active material layer (22) may further include a solid electrolyte. The solid electrolyte may be, for example, a material selected from among the solid electrolytes included in the electrolyte layer (30). The solid electrolyte included in the first negative electrode active material layer (22) may act as a reaction site where lithium metal formation begins within the first negative electrode active material layer (22), a space where the formed lithium metal is stored, or a path for transferring lithium ions. The solid electrolyte may be omitted.

[0284] In the first negative electrode active material layer (22), the content of the solid electrolyte may be high, for example, in an area adjacent to the electrolyte layer (30), and low, for example, in an area adjacent to the negative electrode current collector (21). In the first negative electrode active material layer (22), the solid electrolyte may have a concentration gradient in which the concentration decreases, for example, from an area adjacent to the electrolyte layer (30) to an area adjacent to the negative electrode current collector (21).

[0285] [First negative active material layer: charging capacity]

[0286] The ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer (22) and the initial charge capacity (A) of the positive electrode active material layer is 0.005 to 0.45. The initial charge capacity of the positive electrode active material layer (12) is the first open circuit voltage (1 st Li / Li from open circuit voltage) + The initial charge capacity of the first negative electrode active material layer (22) is determined at the maximum charging voltage. The initial charge capacity of the first negative electrode active material layer (22) is determined at the second open circuit voltage (2 nd Li / Li from open circuit voltage) + It is determined at 0.01 V for .

[0287] The maximum charging voltage is determined by the type of cathode active material. The maximum charging voltage can be, for example, 1.5 V, 2.0 V, 2.5 V, 3.0 V, 3.5 V, 4.0 V, 4.2 V, or 4.3 V. For example, the maximum charging voltage of Li2S or Li2S composite is Li / Li + can be 2.5 V for Li2S or Li2S complex. For example, the maximum charging voltage of Li / Li + It can be 3.0 V for. The ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer (22) and the initial charge capacity (A) of the positive electrode active material layer is, for example, 0.01 to 0.3, 0.01 to 0.2, or 0.05 to 0.1. The initial charge capacity (mAh) of the positive electrode active material layer (12) is obtained by multiplying the charge capacity density (charge specific capacity) (mAh / g) of the positive electrode active material by the mass (g) of the positive electrode active material in the positive electrode active material layer (12). When several types of positive electrode active materials are used, the charge capacity density × mass value is calculated for each positive electrode active material, and the sum of these values ​​is the initial charge capacity of the positive electrode active material layer (12). The initial charge capacity of the first negative electrode active material layer (22) is also calculated in the same way. The initial charge capacity of the first negative electrode active material layer (22) is obtained by multiplying the charge capacity density (mAh / g) of the negative electrode active material by the mass of the negative electrode active material in the first negative electrode active material layer (22). When several types of negative electrode active materials are used, the charge capacity density Х mass value is calculated for each negative electrode active material, and the sum of these values ​​is the initial charge capacity of the first negative electrode active material layer (22). The charge capacity density of each of the positive electrode active material and the negative electrode active material can be measured using an all-solid-state half-cell using lithium metal as a counter electrode.

[0288] The initial charge capacity of each of the positive electrode active material layer (12) and the first negative electrode active material layer (22) is a constant current density, for example, 0.1 mA / cm 2can be directly measured using an all-solid-state half-cell. For the positive electrode, the measurement is made from the first open circuit voltage (OCV) to the maximum charge voltage, for example, 3.0 V (vs. Li / Li + ) can be performed by charging to an operating voltage of up to 0.01 V for the negative electrode, for example, lithium metal, from a second open circuit voltage (OCV). For example, an all-solid-state half-cell having a positive electrode active material layer can be charged to an operating voltage of up to 0.1 mA / cm from a first open circuit voltage to 3.0 V. 2 The all-solid-state half-cell having the first negative active material layer is charged with a constant current of 0.1 mA / cm from the second open circuit voltage to 0.01 V. 2 It can be charged with a constant current. The current density during constant current charging is, for example, 0.2 mA / cm 2 , or 0.5 mA / cm 2 The all-solid-state half-cell having the positive electrode active material layer can be charged from the first open circuit voltage to, for example, 2.5 V, 2.0 V, 3.5 V, or 4.0 V. The maximum charge voltage of the positive electrode active material layer can be determined by the maximum voltage of the battery that satisfies the safety conditions according to JISC8712:2015 of the Japanese Standards Association.

[0289] If the initial charge capacity of the first negative electrode active material layer (22) is too small, the thickness of the first negative electrode active material layer (22) becomes very thin, so that lithium dendrites formed between the first negative electrode active material layer (22) and the negative electrode current collector (21) during repeated charge and discharge processes collapse the first negative electrode active material layer (22), making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (1). If the charge capacity of the first negative electrode active material layer (22) increases excessively, the energy density of the all-solid-state secondary battery (1) decreases and the internal resistance of the all-solid-state secondary battery (1) due to the first negative electrode active material layer (22) increases, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (1).

[0290] The thickness of the first negative electrode active material layer (22) is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode active material layer (12). The thickness of the first negative electrode active material layer (22) is, for example, 1 to 50%, 1 to 40%, 1 to 30%, 1 to 20%, 1 to 10%, or 1 to 5% of the thickness of the positive electrode active material layer (12). The thickness of the first negative electrode active material layer (22) is, for example, 1 µm to 20 µm, 2 µm to 15 µm, or 3 µm to 10 µm. If the thickness of the first negative electrode active material layer (22) is too thin, lithium dendrites formed between the first negative electrode active material layer (22) and the negative electrode current collector (21) collapse the first negative electrode active material layer (22), making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (1). If the thickness of the first negative electrode active material layer (22) increases excessively, the energy density of the all-solid-state secondary battery (1) decreases and the internal resistance of the all-solid-state secondary battery (1) due to the first negative electrode active material layer (22) increases, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (1). If the thickness of the first negative electrode active material layer (22) decreases, for example, the initial charge capacity of the first negative electrode active material layer (22) also decreases.

[0291] [제2 음극활물질층]

[0292] Referring to FIGS. 7 and 8, the all-solid-state secondary battery (1) further includes, after being charged, a second negative electrode active material layer (24) disposed, for example, between the negative electrode current collector (21) and the first negative electrode active material layer (22). The second negative electrode active material layer (24) is a metal layer containing lithium or a lithium alloy. The metal layer contains lithium or a lithium alloy. Therefore, since the second negative electrode active material layer (24) is a metal layer containing lithium, it functions as, for example, a lithium reservoir. The lithium alloy is, for example, 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, etc., but is not limited thereto, and any lithium alloy used in the art may be used. The second negative electrode active material layer (24) may be made of one of these alloys or lithium, or may be made of several types of alloys. The second negative electrode active material layer (24) is, for example, a plated layer. The second negative electrode active material layer (24) is deposited between the first negative electrode active material layer (22) and the negative electrode current collector (21), for example, during the charging process of an all-solid-state secondary battery (1).

[0293] The thickness of the second negative electrode active material layer (24) is not particularly limited, but is, for example, 1 ㎛ to 500 ㎛, 1 ㎛ to 200 ㎛, 1 ㎛ to 150 ㎛, 1 ㎛ to 100 ㎛, or 1 ㎛ to 50 ㎛. If the thickness of the second negative electrode active material layer (24) is too thin, it is difficult for the second negative electrode active material layer (24) to perform the role of a lithium reservoir. If the thickness of the second negative electrode active material layer (24) is too thick, the mass and volume of the all-solid-state secondary battery (1) may increase, and the cycle characteristics of the all-solid-state secondary battery (1) may rather deteriorate.

[0294] Alternatively, in the all-solid-state secondary battery (1), the second negative electrode active material layer (24) may be disposed between the negative electrode current collector (21) and the first negative electrode active material layer (22), for example, before assembling the all-solid-state secondary battery (1). When the second negative electrode active material layer (24) is disposed between the negative electrode current collector (21) and the first negative electrode active material layer (22) before assembling the all-solid-state secondary battery (1), the second negative electrode active material layer (24) acts as a lithium reservoir because it is a metal layer containing lithium. For example, a lithium foil may be disposed between the negative electrode current collector (21) and the first negative electrode active material layer (22) before assembling the all-solid-state secondary battery (1).

[0295] When the second negative electrode active material layer (24) is precipitated by charging after assembling the all-solid-state secondary battery (1), the energy density of the all-solid-state secondary battery (1) increases because the second negative electrode active material layer (24) is not included when assembling the all-solid-state secondary battery (1). When charging the all-solid-state secondary battery (1), the charging is performed in excess of the charging capacity of the first negative electrode active material layer (22). That is, the first negative electrode active material layer (22) is overcharged. At the initial stage of charging, lithium is absorbed into the first negative electrode active material layer (22). The negative electrode active material included in the first negative electrode active material layer (22) forms an alloy or compound with the lithium ions that have moved from the positive electrode (10). When charging exceeds the capacity of the first negative electrode active material layer (22), for example, lithium is deposited on the back surface of the first negative electrode active material layer (22), that is, between the negative electrode current collector (21) and the first negative electrode active material layer (22), and a metal layer corresponding to the second negative electrode active material layer (24) is formed by the deposited lithium. The second negative electrode active material layer (24) is a metal layer mainly composed of lithium (i.e., metallic lithium). This result is obtained, for example, by the negative electrode active material included in the first negative electrode active material layer (22) including a material that forms an alloy or compound with lithium. During discharge, lithium in the first negative electrode active material layer (22) and the second negative electrode active material layer (24), that is, the metal layer, is ionized and moves toward the positive electrode (10). Therefore, it is possible to use lithium as the negative electrode active material in an all-solid-state secondary battery (1). In addition, since the first negative electrode active material layer (22) covers the second negative electrode active material layer (24), it acts as a protective layer for the second negative electrode active material layer (24), i.e., the metal layer, and at the same time, it suppresses the precipitation and growth of lithium dendrites. Accordingly, it suppresses short circuits and capacity reduction of the all-solid-state secondary battery (1), and consequently improves the cycle characteristics of the all-solid-state secondary battery (1).In addition, when the second negative electrode active material layer (24) is placed by charging after assembling the all-solid-state secondary battery (1), the negative electrode (20), i.e., the negative electrode current collector (21) and the first negative electrode active material layer (22) and the region between them are Li-free regions that do not contain lithium (Li) in the initial state or the state after complete discharge of the all-solid-state secondary battery (1).

[0296] [음극집전체]

[0297] The negative electrode layer (20) includes a negative electrode current collector (21). The negative electrode current collector (21) is composed of, for example, a material that does not react with lithium, i.e., does not form an alloy or a compound. The material constituting the negative electrode current collector (21) is, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), etc., but is not necessarily limited thereto, and any material that is used as an electrode current collector in the relevant technical field may be used. The negative electrode current collector (21) may be composed of one type of the above-described metal, or may be composed of an alloy or a coating material of two or more types of metals. The negative electrode current collector (21) is, for example, in the form of a plate or foil.

[0298] Referring to FIGS. 5 and 6, the all-solid-state secondary battery (1) may further include a thin film (23) containing an element capable of forming an alloy with lithium on one surface of the negative electrode collector (21). The thin film (23) is disposed between the negative electrode collector (21) and the first negative electrode active material layer (22). The thin film (23) contains, for example, an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium includes, but is not limited to, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., and any element capable of forming an alloy with lithium in the art may be used. The thin film (23) is composed of one of these metals or an alloy of several types of metals. By placing the thin film (23) on one surface of the negative electrode current collector (21), for example, the deposition shape of the second negative electrode active material layer (24) deposited between the thin film (23) and the first negative electrode active material layer (22) becomes flatter, and the cycle characteristics of the all-solid-state secondary battery (1) can be further improved.

[0299] The thickness of the thin film (23) is, for example, 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. If the thickness of the thin film (23) is less than 1 nm, it may be difficult for the function of the thin film (23) to be exerted. If the thickness of the thin film (23) is excessively thick, the thin film (23) itself absorbs lithium, which reduces the amount of lithium precipitated from the negative electrode, thereby lowering the energy density of the all-solid-state battery and deteriorating the cycle characteristics of the all-solid-state secondary battery (1). The thin film (23) may be disposed on the negative electrode current collector (21) by, for example, a vacuum deposition method, a sputtering method, a plating method, or the like, but is not necessarily limited to these methods, and any method capable of forming the thin film (23) in the relevant technical field may be used.

[0300] Although not shown in the drawing, the negative electrode current collector (21) may include, for example, a base film and a metal layer disposed on one or both sides of the base film. The base film may include, for example, a polymer. The polymer may be, for example, a thermoplastic polymer. The polymer may include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. The polymer may be an insulating polymer. Since the base film includes an insulating thermoplastic polymer, when a short circuit occurs, the base film may soften or liquefy, thereby blocking battery operation and suppressing a rapid increase in current. The metal layer may include, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), or an alloy thereof. The negative electrode current collector (21) may additionally include a metal piece and / or a lead tab. For more specific details regarding the base film, metal layer, metal chip, and lead tab of the negative electrode collector (21), refer to the positive electrode collector (11) described above. By having this structure, the negative electrode collector (21) can reduce the weight of the negative electrode, and consequently, improve the energy density of the negative electrode and lithium battery.

[0301] The present invention is explained in more detail through the following examples and comparative examples. However, the examples are intended to illustrate the present invention and are not intended to limit the scope of the present invention.

[0302] (Manufacturing of weapon fillers)

[0303] Manufacturing Example 1: LiAlO 0.75 Cl 2.5 manufacturing

[0304] Lithium tetrachloroaluminate (LiAlCl4) was prepared by mixing lithium chloride (LiCl) and trichloroaluminum (AlCl3) and heating at 200°C.

[0305] A small amount of metal Al chips was added to molten lithium tetrachloroaluminate to remove impurities.

[0306] Lithium tetrachloroaluminate (LiAlCl4) and Sb2O3 were mixed in a molar ratio of 4:1 and heated at 250°C for 2 hours in an argon atmosphere to remove the volatilized SbCl3 gas, and LiAlO 0.75 Cl 2.5 무기 필러를 제조하였다.

[0307] LiAlO measured at 25℃, 1 atm by AC impedance 0.75 Cl 2.5 The ionic conductivity of the (LACO) inorganic filler was approximately 1 mS / cm. The amplitude voltage used for AC impedance was 50 mV and the frequency range was 1 MHz to 1 Hz. LiAlO 0.75 Cl 2.5 The inorganic filler was amorphous and glassy with a glass transition temperature of LiAlO. 0.75 Cl 2.5 The XRD spectrum of the inorganic filler did not show any crystalline peaks, confirming that it was an amorphous phase. LiAlO 0.75 Cl 2.5 The melting point (Tm) of the inorganic filler was approximately 128°C at 1 atm. LiAlO 0.75 Cl 2.5 The melting point of the inorganic filler was measured using a Differential Scanning Calorimeter (DSC). LiAlO 0.75 Cl 2.5 The glass transition temperature of the inorganic filler was approximately -17 ℃ at 1 atm. LiAlO 0.75 Cl 2.5 The elastic modulus of the inorganic filler was approximately 1.5 GPa at 30°C. LiAlO 0.75 Cl2.5 The glass transition temperature and elastic modulus of the inorganic filler were measured using a dynamic mechanical analyzer (DMA). LiAlO 0.75 Cl 2.5 The viscoelastic creep rate of the inorganic filler is 4×10 -4 % / s. The viscoelastic creep rate was measured using a Universal Test Machine (UTM).

[0308] Manufacturing Example 2: LiAl 1.3 O 1.1 Cl 2.7 Manufacturing of (LACO110)

[0309] The contents of LiCl, AlCl3 and Sb2O3 are LiAl 1.3 O 1.1 Cl 2.7 LiAl was obtained by performing the same procedure as in Manufacturing Example 1, except that the stoichiometry was changed to obtain 1.3 O 1.1 Cl 2.7 (LACO110) was manufactured.

[0310] (Manufacturing of sulfide-based composite cathode active materials)

[0311] Manufacturing Example 3: Li2S-LiI-CNF composite cathode active material

[0312] Li2S and LiI were mixed at a weight ratio of 30:20. The mixture was mechanically milled using a ball mill to prepare a Li2S-LiI composite. The milling conditions were 25°C, 510 rpm, and 10 h.

[0313] Li2S-LiI composite and carbon nanofiber (CNF) were mixed at a weight ratio of 50:10. The mixture was mechanically milled using a ball mill to prepare a Li2S-LiI-CNF composite. The milling conditions were 25°C, 510 rpm, and 10 h. The Li2S-LiI-CNF composite was used as a composite cathode active material.

[0314] Manufacturing Example 4: Manufacturing of a solid membrane

[0315] LiAlO manufactured in Manufacturing Example 1 0.75 Cl 2.5 The inorganic filler was heated to prepare a liquid inorganic filler.

[0316] A solid membrane was prepared by injecting a liquid inorganic filler into a polypropylene / polyethylene / polypropylene three-layer solid membrane and then cooling it to room temperature.

[0317] The thickness of the porous membrane was approximately 20 μm. The porosity of the porous membrane was approximately 50%. The melting point of the porous membrane was approximately 135°C.

[0318] The solid separator is a porous membrane with LiAlO 0.75 Cl 2.5 It has a structure impregnated with weapon filler.

[0319] In the solid separation membrane, the inorganic filler is placed within the pores of the porous membrane. A solid inorganic filler is obtained during the cooling process of the liquid inorganic filler.

[0320] The shape of the inorganic filler conformed to the shape of the pores. The pores acted as a mold or matrix that determined the shape of the inorganic filler.

[0321] The surface profile of the inorganic filler conformed to the surface profile of the pores.

[0322] (Manufacturing of all-solid-state secondary batteries)

[0323] Example 1: Carbon-coated Al cathode current collector / Li6PS5Cl+LACO(37:3) and Li2S-LiI-CNF cathode active material layer / solid separator / solid electrolyte layer (LACO 10 wt%+ Li6PS5Cl 90 wt%) / Ag-C cathode layer

[0324] (Anode layer manufacturing)

[0325] An all-solid-state secondary battery was manufactured in the same manner as Example 1, except that the positive electrode containing a sulfide-based positive electrode active material was used.

[0326] As a cathode active material, the Li2S-LiI-CNF composite manufactured in Manufacturing Example 3 was prepared. As a solid electrolyte, Li6PS5Cl, an argyrodite-type crystal (D50=3.0 ㎛, crystalline), was prepared. As an inorganic filler, LiAlO manufactured in Manufacturing Example 1 was prepared. 0.75 Cl 2.5 was prepared. PTFE was prepared as a binder. These materials were mixed in a weight ratio of composite cathode active material: solid electrolyte: inorganic filler: binder = 60: 37: 3: 1.2 to prepare a cathode mixture. The cathode mixture was obtained by mixing using a ball mill.

[0327] The positive electrode was manufactured by placing the positive electrode active material on one side of a positive electrode current collector made of aluminum foil coated on one side and plate pressing at a pressure of 200 MPa for 10 minutes. The total thickness of the positive electrode layer was approximately 113.8 μm. The thickness of the positive electrode active material layer was approximately 93.8 μm, and the thickness of the carbon-coated aluminum foil was approximately 20 μm.

[0328] (Cathode manufacturing)

[0329] A 10 ㎛ thick SUS foil was prepared as a negative electrode current collector. The composite negative electrode active material manufactured in Manufacturing Example 1 was prepared as a first negative electrode active material. As a second negative electrode active material, a 3:1 weight ratio mixture of carbon black (CB) having a primary particle diameter of approximately 30 nm and silver (Ag) particles having an average particle diameter of approximately 60 nm was prepared.

[0330] 3 g of composite negative electrode active material powder and 1 g of a mixture of carbon black (CB) and silver (Ag) were placed in a container, and 4 g of an NMP solution containing 7 wt% of PVDF binder (Kureha #9300) was added thereto to prepare a mixed solution. A slurry was prepared by stirring the mixed solution while adding NMP little by little to the prepared mixed solution. The prepared slurry was applied to a SUS substrate 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 negative electrode having a first negative electrode active material layer / negative electrode current collector structure. The thickness of the first negative electrode active material layer was approximately 27 μm.

[0331] The ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer and the initial charge capacity (A) of the positive electrode active material layer was less than 1. The initial charge capacity of the positive electrode active material layer was less than 1 at the first open circuit voltage (1 st 4.25 V vs. Li / Li from open circuit voltage) + was determined from the charge up to . The initial charge capacity of the first negative electrode active material layer was determined from the second open circuit voltage (2 nd 0.01 V vs. Li / Li from open circuit voltage) + It was decided from the charging up to .

[0332] (Manufacturing of solid electrolyte layer)

[0333] LiAlO manufactured in Manufacturing Example 1 0.75 Cl 2.5 The inorganic filler was ball milled to prepare a particle size with an average particle diameter of 1㎛.

[0334] Li6PS5Cl solid electrolyte in the form of argyrodite crystals (D 50 =3.0 ㎛, crystalline) and LiAlO 0.75 Cl 2.5A mixture was prepared by adding inorganic filler and acrylic binder. In the mixture, Li6PS5Cl and LiAlO 0.75 Cl 2.5 The total weight of the composite is 98.5 wt%, and the content of the acrylic binder is 1.5 wt%. And Li6PS5Cl and LiAlO 0.75 Cl 2.5 The mixed weight ratio is 90:10.

[0335] The above mixture was provided on a polyethylene terephthalate (PET) substrate and plate pressed at a pressure of 200 MPa for 10 minutes to produce a solid electrolyte layer. The inorganic filler LiAlO 0.75 Cl 2.5 의 녹는점은 약 135 ℃ 이었다.

[0336] (Manufacture of solid separation membrane)

[0337] The solid separation membrane manufactured in Manufacturing Example 4 was used as is.

[0338] (Manufacture of all-solid-state secondary batteries)

[0339] A solid electrolyte layer was placed on the cathode so that the first cathode active material layer was in contact with the solid electrolyte layer, the solid separator was placed on the solid electrolyte layer, and the anode was placed on the solid separator so that the cathode active material layer was in contact with the solid separator, thereby preparing a laminate.

[0340] 85 prepared laminates o The solid electrolyte layer was plate-pressed at 500 MPa for 30 min in C. This pressurization process sintered the solid electrolyte layer, thereby improving battery characteristics. The thickness of the sintered solid electrolyte layer was approximately 20 μm. The pressed laminate was placed in a pouch and vacuum-sealed to manufacture an all-solid-state secondary battery. Part of the positive and negative current collectors were extended outside the sealed battery to be used as positive and negative terminals.

[0341] Example 2: Carbon-coated Al cathode current collector / Li6PS5Cl+LACO(37:3) and Li2S-LiI-CNF cathode active material layer / solid separator / (LACO 10 wt%+ Li6PS5Cl 90 wt%) solid electrolyte layer / solid separator / Ag-C cathode layer

[0342] An all-solid-state secondary battery was manufactured in the same manner as Example 1, except that a solid separator was further placed between the solid electrolyte layer and the first negative electrode active material layer.

[0343] The thickness of each solid membrane was approximately 20 μm.

[0344] Example 3: Al cathode current collector / Li6PS5Cl(40) and Li2S-LiI-CNF cathode active material layer / solid separator / solid electrolyte layer (LACO 10 wt% + Li6PS5Cl 90 wt%) / Ag-C cathode layer

[0345] An all-solid-state secondary battery was manufactured in the same manner as Example 1, except that an aluminum foil cathode current collector without a carbon coating layer was used and the content ratio of the sulfide-based solid electrolyte and the inorganic filler in the cathode active material layer was changed from 14:1 to 15:0 (sulfide-based solid electrolyte only).

[0346] Example 4: Carbon-coated Al cathode current collector / Li6PS5Cl+LACO(37:3) and Li2S-LiI-CNF cathode active material layer / solid separator / (LACO 10 wt%+bimodal Li6PS5Cl 90 wt%) solid electrolyte layer / Ag-C cathode layer

[0347] An all-solid-state secondary battery was manufactured using the same method as Example 1, except that the solid electrolyte layer was manufactured according to the following process.

[0348] Li6PS5Cl solid electrolyte in the form of argyrodite crystals (D 50 =3.0 μm, crystalline), Li6PS5Cl solid electrolyte (D 50 =1.0 ㎛, crystalline) and LiAlO manufactured in Manufacturing Example 1 0.75 Cl 2.5A mixture was prepared by adding inorganic filler and acrylic binder. In the mixture, Li6PS5Cl and LiAlO 0.75 Cl 2.5 The total weight of the composite is 98.5 wt%, and the content of the acrylic binder is 1.5 wt%. And Li6PS5Cl and LiAlO 0.75 Cl 2.5 The mixing weight ratio is 90:10. And Li6PS5Cl solid electrolyte (D 50 =3.0 μm, crystalline) and Li6PS5Cl solid electrolyte (D 50 =1.0 ㎛, crystalline) is a mixing weight ratio of 2:8.

[0349] The above mixture was provided on a PET substrate and plate pressed at a pressure of 20 MPa for 10 minutes to produce a solid electrolyte layer. Inorganic filler LiAlO 0.75 Cl 2.5 The melting point was about 135°C.

[0350] Example 5: Carbon-coated Al cathode current collector / Li6PS5Cl+LACO(37:3) and Li2S-LiI-CNF cathode active material layers / solid separator / first solid electrolyte layer (LACO 10 wt%+ Li6PS5Cl 90 wt%) / second solid electrolyte layer (LACO 5 wt%+ Li6PS5Cl 95 wt%) / Ag-C cathode layer

[0351] An all-solid-state secondary battery was manufactured using the same method as Example 1, except that the first solid electrolyte layer and the second solid electrolyte layer were manufactured according to the following process. The first solid electrolyte layer was arranged to be in contact with the negative electrode, and the second solid electrolyte layer was arranged to be in contact with the positive electrode.

[0352] Li6PS5Cl solid electrolyte in the form of argyrodite crystals (D 50 =3.0 ㎛, crystalline) and LiAlO manufactured in Manufacturing Example 1 0.75 Cl 2.5A mixture was prepared by adding inorganic filler and acrylic binder. In the mixture, Li6PS5Cl and LiAlO 0.75 Cl 2.5 The total weight of the composite is 98.5 wt%, and the content of the acrylic binder is 1.5 wt%. And Li6PS5Cl and LiAlO 0.75 Cl 2.5 The mixing weight ratio is 95:5.

[0353] The first mixture was provided on a PET substrate and plate pressed at a pressure of 200 MPa for 10 minutes to produce a first solid electrolyte layer. Inorganic filler LiAlO 0.75 Cl 2.5 Its melting point was about 135℃.

[0354] Li6PS5Cl solid electrolyte in the form of argyrodite crystals (D 50 =3.0 ㎛, crystalline) and LiAlO manufactured in Manufacturing Example 1 0.75 Cl 2.5 A second mixture was prepared by adding inorganic filler and acrylic binder. In the mixture, Li6PS5Cl and LiAlO 0.75 Cl 2.5 The total weight of the composite is 98.5 wt%, and the content of the acrylic binder is 1.5 wt%. And Li6PS5Cl and LiAlO 0.75 Cl 2.5 The mixing weight ratio is 90:10.

[0355] The second mixture was provided on a substrate and plate pressed at a pressure of 200 MPa for 10 minutes to produce a second solid electrolyte layer. Inorganic filler LiAlO 0.75 Cl 2.5 Its melting point was about 135℃.

[0356] Example 6: Carbon-coated Al cathode current collector / Li6PS5Cl+LACO(37:3) and Li2S-LiI-CNF cathode active material layer / (LACO 10 wt%+ Li6PS5Cl 90 wt%) solid electrolyte layer / Ag-C cathode layer

[0357] LiAlO of Manufacturing Example 1 as an inorganic filler in the manufacture of the positive electrode active material layer and the solid electrolyte layer 0.75 Cl 2.5 Instead, LiAl of manufacturing example 2 1.3 O 1.1 Cl 2.7 An all-solid-state secondary battery was manufactured using the same method as Example 1, except that (LACO110) was used.

[0358] Example 7: Carbon-coated Al cathode current collector / Li6PS5Cl+LACO(14:1) and NCA cathode active material layer / solid separator / (LACO 10 wt%+ Li6PS5Cl 90 wt%) solid electrolyte layer / Ag-C cathode layer

[0359] An all-solid-state secondary battery was manufactured in the same manner as Example 1, except that the following process was followed when manufacturing the positive electrode layer.

[0360] (Anode layer manufacturing)

[0361] LiNi coated with Li2O-ZrO2 (LZO) as a cathode active material 0.8 Co 0.15 Al 0.05 O2(NCA) was prepared. LZO-coated NCA was prepared according to the method disclosed in Korean Patent Publication No. 10-2016-0064942. Li6PS5Cl, an argyrodite-type crystal (D50 = 0.5 μm, crystalline), was prepared as a solid electrolyte. LiAlO prepared in Manufacturing Example 1 was used as an inorganic filler. 0.75 Cl 2.5A polytetrafluoroethylene (PTFE) binder was prepared as a binder. Amorphous carbon nanotubes (CNTs) were prepared as a conductive material. These materials were mixed with a xylene solvent in a weight ratio of positive electrode active material: solid electrolyte: inorganic filler: conductive material: binder = 85: 14: 1: 3: 2, and a slurry was formed into a sheet shape, and then vacuum-dried at 40°C for 8 hours to manufacture a positive electrode sheet. The manufactured positive electrode sheet was placed on the carbon layer of a positive electrode current collector made of aluminum foil coated with a carbon layer on one side, and 85 o The anode layer was manufactured by heated roll pressing of C. The total thickness of the anode layer was approximately 112 μm. The thickness of the carbon-coated aluminum foil was approximately 20 μm. The thickness of the carbon layer was approximately 1 μm.

[0362] The elastic modulus of Li6PS5Cl was approximately 22 to 30 GPa at 30°C. The elastic modulus of Li6PS5Cl was measured using a dynamic mechanical analyzer (DMA).

[0363] Example 8: Carbon-coated Al cathode current collector / Li6PS5Cl+LACO(14:1) and NCA cathode active material layer / solid separator / (LACO 10 wt%+bimodal Li6PS5Cl 90 wt%)(bimodal sulfide system SE) solid electrolyte layer / Ag-C cathode layer

[0364] An all-solid-state secondary battery was manufactured using the same method as Example 7, except that the solid electrolyte layer was manufactured according to the following process.

[0365] Li6PS5Cl solid electrolyte in the form of argyrodite crystals (D 50 =3.0 μm, crystalline), Li6PS5Cl solid electrolyte (D 50 =1.0 ㎛, crystalline) and LiAlO manufactured in Manufacturing Example 1 0.75 Cl 2.5A mixture was prepared by adding inorganic filler and acrylic binder. In the mixture, Li6PS5Cl and LiAlO 0.75 Cl 2.5 The total weight of the composite is 98.5 wt%, and the content of the acrylic binder is 1.5 wt%. And Li6PS5Cl and LiAlO 0.75 Cl 2.5 The mixing weight ratio is 90:10. And Li6PS5Cl solid electrolyte (D 50 =3.0 μm, crystalline) and Li6PS5Cl solid electrolyte (D 50 =1.0 ㎛, crystalline) is a mixing weight ratio of 2:8.

[0366] The above mixture was provided on a substrate and plate pressed at a pressure of 200 MPa for 10 minutes to produce a solid electrolyte layer. Inorganic filler LiAlO 0.75 Cl 2.5 Its melting point was about 135 ℃.

[0367] Example 9: Carbon-coated Al cathode current collector / Li6PS5Cl+LACO(14:1) and NCA cathode active material layer / solid separator / (LACO 10 wt%+ Li6PS5Cl 90 wt%) first solid electrolyte layer / (LACO 5 wt%+ Li6PS5Cl 95 wt%) second solid electrolyte layer / Ag-C cathode layer

[0368] An all-solid-state secondary battery was manufactured in the same manner as Example 8, except that the first solid electrolyte layer and the second solid electrolyte layer were manufactured according to the following process. The first solid electrolyte layer was arranged to be in contact with the negative electrode, and the second solid electrolyte layer was arranged to be in contact with the positive electrode.

[0369] Li6PS5Cl solid electrolyte in the form of argyrodite crystals (D 50 =3.0 ㎛, crystalline) and LiAlO manufactured in Manufacturing Example 1 0.75 Cl 2.5A first mixture was prepared by adding inorganic filler and acrylic binder. In the mixture, Li6PS5Cl and LiAlO 0.75 Cl 2.5 The total weight of the composite is 98.5 wt%, and the content of the acrylic binder is 1.5 wt%. And Li6PS5Cl and LiAlO 0.75 Cl 2.5 The mixed weight ratio is 95:5.

[0370] The first mixture was provided on a PET substrate and plate pressed at a pressure of 200 MPa for 10 minutes to produce a first solid electrolyte layer. Inorganic filler LiAlO 0.75 Cl 2.5 The melting point was about 135°C.

[0371] Li6PS5Cl solid electrolyte in the form of argyrodite crystals (D 50 =3.0 ㎛, crystalline) and LiAlO manufactured in Manufacturing Example 1 0.75 Cl 2.5 A second mixture was prepared by adding inorganic filler and acrylic binder. In the mixture, Li6PS5Cl and LiAlO 0.75 Cl 2.5 The total weight of the composite is 98.5 wt%, and the content of the acrylic binder is 1.5 wt%. And Li6PS5Cl and LiAlO 0.75 Cl 2.5 의 혼합중량비는 90:10이다.

[0372] The second mixture was provided on a PET substrate and plate pressed at a pressure of 200 MPa for 10 minutes to produce a second solid electrolyte layer. Inorganic filler LiAlO 0.75 Cl 2.5 의 녹는점은 약 135 ℃ 이었다.

[0373] Example 10: bare Al / Li6PS5Cl(15) and NCA / solid membrane / (LACO 10 wt% + Li6PS5Cl 90 wt%) solid electrolyte layer / Ag-C cathode layer

[0374] An all-solid-state secondary battery was manufactured in the same manner as in Example 8, except that an aluminum foil cathode current collector without a carbon coating layer was used and the content ratio of the sulfide-based solid electrolyte and the inorganic filler in the cathode active material layer was changed from 14:1 to 15:0 (sulfide-based solid electrolyte only).

[0375] Comparative Example 1: bare Al / Li6PS5Cl(40) and Li2S-LiI-CNF / Li6PS5Cl / Ag-C cathode layers

[0376] An all-solid-state secondary battery was manufactured in the same manner as in Example 1, except that an aluminum foil cathode current collector without a carbon coating layer was used, the content ratio of the sulfide-based solid electrolyte and the inorganic filler was changed from 90:10 to 40:0 (sulfide-based solid electrolyte only), and the solid electrolyte layer was manufactured according to the following method.

[0377] Li6PS5Cl solid electrolyte in the form of argyrodite crystals (D 50 =3.0 ㎛, crystalline) and an acrylic binder were added at a weight ratio of 98.5:1.5 to prepare a mixture. Octyl acetate was added to the mixture and stirred to prepare a slurry. The prepared slurry was applied onto a PET substrate using a bar coater and dried in air at 80°C for 10 minutes to prepare a laminate. The prepared laminate was vacuum-dried at 80°C for 2 hours to prepare a solid electrolyte layer.

[0378] Comparative Example 2: Bare Al / Li6PS5Cl(15) and NCA / Li6PS5Cl / Ag-C cathode layers

[0379] An all-solid-state secondary battery was manufactured in the same manner as in Example 7, except that an aluminum foil cathode current collector without a carbon coating layer was used, the content ratio of the sulfide-based solid electrolyte and the inorganic filler was changed from 14:1 to 15:0 (sulfide-based solid electrolyte only), and the solid electrolyte layer was manufactured according to the following method.

[0380] Li6PS5Cl solid electrolyte in the form of argyrodite crystals (D 50 =3.0 ㎛, crystalline) and an acrylic binder were added at a weight ratio of 98.5:1.5 to prepare a mixture. Octyl acetate was added to the mixture and stirred to prepare a slurry. The prepared slurry was applied onto a PET substrate using a bar coater and dried in air at 80°C for 10 minutes to prepare a laminate. The prepared laminate was vacuum-dried at 80°C for 2 hours to prepare a solid electrolyte layer.

[0381] Evaluation Example 1: Charge / Discharge Test

[0382] The charge / discharge characteristics of the all-solid-state secondary batteries manufactured in Examples 1 to 6 and Comparative Example 1 were evaluated by the following charge / discharge test. The charge / discharge test was performed by placing the all-solid-state secondary batteries in a constant temperature bath at 45°C.

[0383] The first cycle involved charging for 12.5 hours at a constant current of 0.1 C until the battery voltage reached 2.5 to 2.8 V. Subsequently, discharging was performed for 12.5 hours at a constant current of 0.1 C until the battery voltage reached 0.3 V.

[0384] The discharge capacity of the first cycle was taken as the standard capacity. The standard capacity is expressed as the specific capacity of Li2S-LiI-CNF in Table 1 below.

[0385] After the second cycle, charging and discharging were performed up to 500 cycles under the same conditions as the first cycle. The measurement results are shown in Table 2 below.

[0386] The cycle count is the number of cycles required for the discharge capacity to decrease to 80% of the standard capacity after the second cycle. A higher cycle count is considered to indicate better life characteristics.

[0387] Evaluation Example 2: High-Rate Characteristic Evaluation

[0388] The high-rate characteristics of the all-solid-state secondary batteries of Examples 1 to 6 and Comparative Example 1 were evaluated by the following charge-discharge test. The charge-discharge test was performed by placing the solid-state secondary batteries in a constant-temperature bath at 45°C.

[0389] The all-solid-state secondary battery was charged at a constant current of 0.1 C rate at 45°C until the voltage reached 2.5 V (vs. Li), and then cut-off at a current of 0.05 C rate while maintaining 2.5 V in constant voltage mode. Subsequently, the battery was discharged at a constant current of 0.1 C rate until the voltage reached 0.3 V (vs. Li) (formation cycle).

[0390] The solid-state secondary battery, which had undergone a Mars cycle, was charged at a constant current of 0.2 C rate at 45°C until the voltage reached 2.5 V (vs. Li). Subsequently, it was discharged at a constant current of 0.2 C rate until the voltage reached 0.3 V (vs. Li) (first cycle).

[0391] The solid-state secondary battery that had undergone the first cycle was charged at a constant current of 0.2 C rate at 45°C until the voltage reached 4.3 V (vs. Li). Subsequently, it was discharged at a constant current of 0.33 C rate until the voltage reached 2.5 V (vs. Li) (second cycle).

[0392] The solid-state secondary battery that had undergone the second cycle was charged at a constant current of 0.2 C rate at 45°C until the voltage reached 2.5 V (vs. Li). Subsequently, it was discharged at a constant current of 0.5 C rate until the voltage reached 0.3 V (vs. Li) (third cycle).

[0393] The solid-state secondary battery that had undergone the third cycle was charged at a constant current of 0.2 C rate at 45°C until the voltage reached 2.5 V (vs. Li). Subsequently, it was discharged at a constant current of 1.0 C rate until the voltage reached 0.3 V (vs. Li) (4th cycle).

[0394] In all charge / discharge cycles, a 10-minute pause was provided after each charge / discharge cycle. Some of the results of the room-temperature charge / discharge experiments are shown in Table 1 below. The high-rate characteristics are defined by the following mathematical equation (2).

[0395] <Mathematical Formula 2>

[0396] High-rate characteristic [%] = [4th cycle discharge capacity (1.0 C) / Mars cycle discharge capacity (0.1 C)] × 100

[0397] The discharge capacity [mAh / g], the number of cycles [times], and the high-rate characteristics [%] are shown in Table 1. Example 1: Carbon-coated Al positive electrode collector / Li6PS5Cl+LACO(37:3) and Li2S-LiI-CNF positive electrode active material layer / solid separator / (LACO 10 wt% + Li6PS5Cl 90 wt%) solid electrolyte layer / Ag-C negative electrode layer 83038088. Example 2: Carbon-coated Al positive electrode collector / Li6PS5Cl+LACO(37:3) and Li2S-LiI-CNF positive electrode active material layer / solid separator / (LACO 10 wt% + Li6PS5Cl 90 wt%) solid electrolyte layer / solid separator / Ag-C negative electrode layer 72021081. Example 3: Al positive electrode collector / Li6PS5Cl(40) and Li2S-LiI-CNF positive electrode active material layer / solid separator / (LACO 10 wt% + Li6PS5Cl 90 wt%) solid electrolyte layer / Ag-C negative electrode layer79033085Example 4: Carbon-coated Al positive electrode collector / Li6PS5Cl+LACO(37:3) and Li2S-LiI-CNF positive electrode active material layer / solid separator / (LACO 10 wt% + bimodal Li6PS5Cl 90 wt%) solid electrolyte layer / Ag-C negative electrode layer95048093Example 5: Carbon-coated Al positive electrode collector / Li6PS5Cl+LACO(37:3) and Li2S-LiI-CNF positive electrode active material layer / solid separator / (LACO 10 wt% + Li6PS5Cl 90 wt%) first solid electrolyte layer / (LACO 5 wt% + Li6PS5Cl 95 wt%) second solid electrolyte layer / Ag-C Cathode layer 96052094.5 Comparative example 1: bare Al / Li6PS5Cl(40) and Li2S-LiI-CNF / Li6PS5Cl / Ag-C cathode layer 65615379

[0398] As shown in Table 1, the all-solid-state secondary batteries of Examples 1 to 5 exhibited improved charge-discharge characteristics compared to the all-solid-state secondary battery of Comparative Example 1. Among them, the all-solid-state secondary battery of Example 1 had excellent charge-discharge characteristics by including inorganic fillers in both the solid electrolyte layer and the positive electrode active material layer, and it was found that the charge-discharge characteristics were further improved compared to the all-solid-state secondary battery of Example 7, which contained inorganic fillers only in the solid electrolyte layer.

[0399] Although the all-solid-state secondary battery of Example 6 is not shown in Table 1, it exhibited charge-discharge characteristics at a similar level to the all-solid-state secondary battery of Example 1.

[0400] Evaluation Example 3: Charge / Discharge Test

[0401] The charge / discharge characteristics of the all-solid-state secondary batteries manufactured in Examples 7-10 and Comparative Example 2 were evaluated by the following charge / discharge test. The charge / discharge test was performed by placing the all-solid-state secondary batteries in a constant temperature bath at 45°C.

[0402] The first cycle involved charging for 12.5 hours at a constant current of 0.1 C until the battery voltage reached 4.3 V. Subsequently, discharging was performed for 12.5 hours at a constant current of 0.1 C until the battery voltage reached 2.5 V.

[0403] The discharge capacity of the first cycle was taken as the standard capacity. The standard capacity is shown as the specific capacity of NCA in Table 1 below.

[0404] After the second cycle, charging and discharging were performed up to 500 cycles under the same conditions as the first cycle. The measurement results are shown in Table 1 below.

[0405] The cycle count is the number of cycles required for the discharge capacity to decrease to 80% of the standard capacity after the second cycle. A higher cycle count is considered to indicate better life characteristics.

[0406] Evaluation Example 4: High-Rate Characteristic Evaluation

[0407] The high-rate characteristics of the all-solid-state secondary batteries of Examples 7-10 and Comparative Example 2 were evaluated by the following charge-discharge test. The charge-discharge test was performed by placing the solid-state secondary batteries in a constant-temperature bath at 45°C.

[0408] The all-solid-state secondary battery was charged at a constant current of 0.1 C rate at 45°C until the voltage reached 4.3 V (vs. Li), and then cut-off at a current of 0.05 C rate while maintaining 4.3 V in constant voltage mode. Subsequently, the battery was discharged at a constant current of 0.1 C rate until the voltage reached 2.5 V (vs. Li) during discharge (formation cycle).

[0409] The solid-state secondary battery that had undergone the Mars cycle was charged at a constant current of 0.2 C rate at 45°C until the voltage reached 4.3 V (vs. Li). Subsequently, it was discharged at a constant current of 0.2 C rate until the voltage reached 2.5 V (vs. Li) (first cycle).

[0410] The solid-state secondary battery that had undergone the first cycle was charged at a constant current of 0.2 C rate at 45°C until the voltage reached 4.3 V (vs. Li). Subsequently, it was discharged at a constant current of 0.33 C rate until the voltage reached 2.5 V (vs. Li) (second cycle).

[0411] The solid-state secondary battery that had undergone the second cycle was charged at a constant current of 0.2 C rate at 45°C until the voltage reached 4.3 V (vs. Li). Subsequently, it was discharged at a constant current of 0.5 C rate until the voltage reached 2.5 V (vs. Li) (third cycle).

[0412] The solid-state secondary battery that had undergone the third cycle was charged at a constant current of 0.2 C rate at 45°C until the voltage reached 4.3 V (vs. Li). Subsequently, it was discharged at a constant current of 1.0 C rate until the voltage reached 2.5 V (vs. Li) (4th cycle).

[0413] In all charge / discharge cycles, a 10-minute pause was observed after each charge / discharge cycle. Some of the results of the room-temperature charge / discharge experiments are shown in Table 2 below. The high-rate characteristics are defined by the following mathematical equation (1).

[0414] <Mathematical Formula 1>

[0415] High-rate characteristic [%] = [4th cycle discharge capacity (1.0 C) / Mars cycle discharge capacity (0.1 C)] × 100

[0416] The discharge capacity [mAh / g], the number of cycles [times], and the high-rate characteristics [%] are shown in Table 1. Example 7: Carbon-coated Al positive electrode collector / Li6PS5Cl+LACO(14:1) and NCA positive electrode active material layer / solid separator / (LACO 10 wt%+ Li6PS5Cl 90 wt%) solid electrolyte layer / Ag-C negative electrode layer 18363593.1 Example 8: Carbon-coated Al positive electrode collector / Li6PS5Cl+LACO(14:1) and NCA positive electrode active material layer / solid separator / (LACO 10 wt%+bimodal Li6PS5Cl 90 wt%)(bimodal sulfide system SE) solid electrolyte layer / Ag-C negative electrode layer 18871295.1 Example 9: Carbon-coated Al positive electrode collector / Li6PS5Cl+LACO(14:1) and NCA positive electrode active material layer / solid separator / (LACO 10 wt% + Li6PS5Cl 90 wt%) First solid electrolyte layer / (LACO 5 wt% + Li6PS5Cl 95 wt%) Second solid electrolyte layer / Ag-C cathode layer 19178096.5 Example 10: bare Al / Li6PS5Cl(15) and NCA / solid membrane / (LACO 10 wt% + Li6PS5Cl 90 wt%) solid electrolyte layer / Ag-C cathode layer 18148691.8 Comparative example 2: bare Al / Li6PS5Cl(15) and NCA / Li6PS5Cl / Ag-C cathode layer 180.138590.6

[0417] As shown in Table 2, the all-solid-state secondary batteries of Examples 7 to 10 exhibited improved charge / discharge characteristics compared to the all-solid-state secondary battery of Comparative Example 2.

[0418] The all-solid-state secondary batteries of Examples 7 to 10 had excellent charge-discharge characteristics by including inorganic fillers in both the solid electrolyte layer and the positive electrode active material layer. In particular, the all-solid-state secondary battery of Example 7 had a solid electrolyte layer containing an inorganic filler, but compared to the all-solid-state secondary battery of Example 10, which did not include an inorganic filler in the positive electrode active material layer, the inclusion of an inorganic filler in the positive electrode active material layer improved stability and suppressed an increase in internal resistance, thereby further improving the charge-discharge characteristics.

[0419] In contrast, the all-solid-state secondary battery of Comparative Example 2 did not include a solid electrolyte layer containing an inorganic filler, and thus the charge-discharge characteristics were lower than those of the all-solid-state secondary batteries of Examples 7 to 10 due to an increase in interfacial resistance caused by volume change during charge-discharge.

[0420] Although not shown in the drawing, it was confirmed that a lithium metal layer, which is a second negative electrode active material layer, was formed between the first negative electrode active material layer and the negative electrode current collector after initial charging in the all-solid-state secondary batteries of Examples 7 to 10.

[0421] The formation of the lithium metal layer was confirmed through cross-sectional scanning electron microscope images of the all-solid-state secondary battery.

[0422] Evaluation Example 4: Shutdown Temperature Measurement

[0423] The impedance of the all-solid-state secondary batteries of Examples 1 to 8 and Comparative Example 1 was measured while the temperature was increased from room temperature (i.e., 25°C) to 180°C at a rate of 10°C min. The temperature at which the impedance of the all-solid-state secondary battery increased by 100 times the initial value was evaluated as the shutdown temperature.

[0424] In the all-solid-state secondary batteries of Examples 1 to 8, the shutdown temperature was 130°C to 160°C.

[0425] In contrast, the shutdown temperature of the all-solid-state secondary battery of Comparative Example 1 was not measured.

[0426] Therefore, it was confirmed that the all-solid-state secondary batteries of Examples 1 to 7 can effectively block ignition due to thermal runaway, etc., with a solid separator, compared to the all-solid-state secondary battery of Comparative Example 1.

Claims

1. It comprises a positive electrode layer; a negative electrode layer; a solid electrolyte layer between the positive electrode layer and the negative electrode layer; and a solid separator disposed between the positive electrode layer and the solid electrolyte layer and between the negative electrode layer and the solid electrolyte layer. The above negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer on one surface of the negative electrode current collector, The above solid electrolyte layer includes a sulfide-based solid electrolyte and an inorganic filler, The above solid separation membrane comprises a porous membrane and an inorganic filler, An all-solid-state secondary battery, wherein the inorganic filler comprises a lithium metal oxyhalide represented by the following chemical formula 1: <Chemical Formula 1> Li a M b O c Cl d In chemical formula 1, 0 <a≤3; 0<b≤3; 0<c≤3; 0<d≤8; c<d; a / (a+b+c+d)<0.5, M is a metal selected from groups 3 to 15 of the periodic table.

2. An all-solid-state secondary battery in the first paragraph, wherein the content of the inorganic filler in the solid electrolyte layer is 1 to 15 parts by weight based on 100 parts by weight of the solid electrolyte layer.

3. An all-solid-state secondary battery in accordance with claim 1, wherein an inorganic filler is disposed within the pores of a sulfide-based solid electrolyte in the solid electrolyte layer.

4. In the first paragraph, the inorganic filler is amorphous or glassy, and the glass transition temperature of the inorganic filler is 20°C or lower. The melting point of the above-mentioned inorganic filler is 100 ℃ or higher, The above inorganic filler is an ion-conductive inorganic filler, The ionic conductivity of the above inorganic filler is 0.01 mS / cm or more at 25 ℃ and 1 atm, An all-solid-state secondary battery, wherein the elastic modulus of the above-mentioned inorganic filler at 30°C is 10 GPa or less.

5. An all-solid-state secondary battery in the first paragraph, wherein the metal M of the lithium metal oxyhalide comprises Fe, Ga, In, As, Sb, Mo, Bi, B or a combination thereof.

6. In the first paragraph, the lithium metal oxyhalide is LiAl b O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiFe b O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiGa b O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiIn b O c Cl d (0 <c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiAs b O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiSb b O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiMo b O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiBi b O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiB b O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; c<d; 1 / (1+b+c+d)<0.5); LiAl b-e Fe e O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; 0<e<b; c<d; 1 / (1+b+c+d+e)<0.5); LiAl b-e Ga e O c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; 0<e<b; c<d; 1 / (1+b+c+d+e)<0.5); LiAl b-e In e Oh c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; 0<e<b; c<d; 1 / (1+b+c+d+e)<0.5); LiAl b-e I e Oh c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; 0<e<b; c<d; 1 / (1+b+c+d+e)<0.5); LiAl b-e Sat e Oh c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; 0<e<b; c<d; 1 / (1+b+c+d+e)<0.5); LiAl b-e Mo e Oh c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; 0<e<b; c<d; 1 / (1+b+c+d+e)<0.5); LiAl b-e Bi e Oh c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; 0<e<b; c<d; 1 / (1+b+c+d+e)<0.5); LiAl b-e B e Oh c Cl d (0 <b≤3; 0<c≤2; 0<d≤4; 0<e<b; c<d; 1 / (1+b+c+d+e)<0.5) 또는 이들의 조합을 포함하는, 전고체 이차전지.

7. In the first paragraph, the sulfide-based solid electrolyte in the solid electrolyte layer includes a small-diameter first sulfide-based solid electrolyte having an average particle diameter of 0.5 ㎛ to 1.9 ㎛ and a large-diameter first sulfide-based solid electrolyte having an average particle diameter of 2 ㎛ to 5 ㎛. An all-solid-state secondary battery, wherein the content of the first small-particle-sized sulfide-based solid electrolyte is greater than the content of the second large-particle-sized sulfide-based solid electrolyte.

8. In the first paragraph, the solid electrolyte layer contains a first solid electrolyte layer including a sulfide-based solid electrolyte and an inorganic filler, and a second solid electrolyte layer including a sulfide-based solid electrolyte and an inorganic filler. The first solid electrolyte layer is arranged to be in contact with the cathode, and the second solid electrolyte layer is arranged to be in contact with the anode. An all-solid-state secondary battery, wherein the content of the inorganic filler in the first solid electrolyte layer is smaller than the content of the inorganic filler in the first solid electrolyte layer.

9. In the first paragraph, the inorganic filler is provided within the pores of the solid separation membrane, The shape of the above-mentioned inorganic filler conforms to the shape of the above-mentioned pores, An all-solid-state secondary battery, wherein the surface profile of the above-mentioned inorganic filler conforms to the surface profile of the above-mentioned pores.

10. An all-solid-state secondary battery according to claim 1, wherein the solid separator further comprises a sulfide-based solid electrolyte.

11. In the first paragraph, the solid separation membrane is liquid at 120°C or higher, The shutdown temperature of the porous membrane is 100°C or higher, and the melting point of the porous membrane is higher than 120°C. An all-solid-state secondary battery, wherein the porous membrane is a flexible solid separator, the porous membrane is an insulating solid separator, the porous membrane is a flame-retardant solid separator, the thickness of the porous membrane is 1 to 200 ㎛, and the porosity of the solid separator is 20 to 99%.

12. In paragraph 1, the cathode active material includes an oxide-based cathode active material, a sulfide-based cathode active material, or a combination thereof. The above oxide-based cathode active material includes a lithium transition metal oxide, a metal oxide, or a combination thereof, and the lithium transition metal oxide includes lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt mangense oxide, lithium manganate, lithium iron phosphate, or a combination thereof, and the lithium oxide includes iron oxide, vanadium oxide, or a combination thereof. An all-solid-state secondary battery, wherein the sulfide-based cathode active material comprises nickel sulfide, copper sulfide, Li2S, a Li2S-containing complex, or a combination thereof.

13. In the 12th paragraph, the Li2S complex is a composite of Li2S and a lithium salt, An all-solid-state secondary battery comprising a composite of Li2S and a carbon-based material, a composite of Li2S and a carbon-based material and a solid electrolyte, a composite of Li2S and a solid electrolyte, a composite of Li2S and a carbon-based material and a lithium salt, a composite of Li2S and a lithium salt, a composite of Li2S and a metal carbide, a composite of Li2S and a carbon-based material and a metal carbide, a composite of Li2S and a metal nitride, a composite of Li2S and a carbon-based material and a metal nitride, or a combination thereof.

14. In the first paragraph, the sulfide-based solid electrolyte is Li2S-P2S5, Li2S-P2S5-LiX, 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, Z is one of Ge, Zn or Ga, Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q , p, q are positive numbers, 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 , 0≤x≤2, and wherein the sulfide-based solid electrolyte comprises an argyrodite-type solid electrolyte, the argyrodite-type solid electrolyte comprises at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I, and the density of the argyrodite-type solid electrolyte is 1.5 to 2.0 g / cc.

15. An all-solid-state secondary battery according to claim 1, wherein the positive electrode active material layer further comprises at least one selected from a conductive material and a binder, wherein the conductive material comprises a carbon-based material, the carbon-based material is amorphous, the carbon-based material comprises a fibrous carbon-based material, the fibrous carbon-based material comprises a fibrous carbon nanostructure, and the fibrous carbon nanostructure comprises carbon nanofibers, carbon nanotubes, carbon nanobelts, carbon nanorods, or a combination thereof.

16. An all-solid-state secondary battery according to claim 1, further comprising an interlayer between the positive electrode current collector and the positive electrode active material layer, wherein the interlayer comprises a carbon-based conductive material.

17. In the first paragraph, the first negative electrode active material layer includes a negative electrode active material and a binder, The negative electrode active material has a particle form, the average particle diameter of the negative electrode active material is 4 ㎛ or less, the negative electrode active material includes at least one selected from a carbon-based negative electrode active material and a metal or metalloid negative electrode active material, and the carbon-based negative electrode active material includes amorphous carbon, crystalline carbon, porous carbon, or a combination thereof. An all-solid-state secondary battery, wherein the metal or metalloid negative electrode active material comprises gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), or a combination thereof.

18. In the 17th paragraph, the negative electrode active material comprises a mixture of first particles made of amorphous carbon and second particles made of a metal or a metalloid, and the content of the second particles is 1 to 60 wt% based on the total weight of the mixture. Further comprising a second negative electrode active material layer disposed between the negative electrode current collector and the first negative electrode active material layer and between the negative electrode current collector and the electrolyte layer, An all-solid-state secondary battery, wherein the second negative electrode active material layer is a metal layer, and the metal layer includes lithium or a lithium alloy.

19. In the first paragraph, an all-solid-state secondary battery, wherein the positive electrode active material layer comprises a lithium sulfide-based positive electrode active material and an inorganic filler, and the inorganic filler is a lithium metal oxyhalide represented by the following chemical formula 1: <Chemical Formula 1> Li a M b O c Cl d In chemical formula 1, 0 <a≤3; 0<b≤3; 0<c≤3; 0<d≤8; c<d; a / (a+b+c+d)<0.5, M is a metal selected from groups 3 to 15 of the periodic table.

20. In the first paragraph, at least one of the positive electrode current collector and the negative electrode current collector includes a base film and a metal layer disposed on one or both sides of the base film, The above base film comprises a polymer, and the polymer comprises polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI) or a combination thereof, The above metal layer comprises indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li) or an alloy thereof, An all-solid-state secondary battery further comprising an inert member disposed on one side of the positive electrode.

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