Positive electrode and all-solid-state battery comprising same

Abstract

The present invention relates to a positive electrode and an all-solid-state battery comprising same, wherein the positive electrode comprises: a positive electrode current collector; and a positive electrode active material layer disposed on the positive electrode current collector, wherein the positive electrode active material layer includes a first positive electrode active material, a second positive electrode active material, and a solid electrolyte, wherein the first positive electrode active material includes a first composite containing a first lithium sulfide, a metal halide salt, and a first carbon-based conductive material, and the second positive electrode active material is a material formed by combining a compound represented by Li7-bPS6-bClb (0≤b≤2) and a second carbon-based conductive material with each other.

Description

Anode and all-solid-state battery including the same

[0001] The present invention relates to a positive electrode and an all-solid-state battery including the same.

[0002] Recently, driven by industrial demands, the development of batteries with high energy density and safety is actively underway. For example, lithium-ion batteries are being commercialized not only in the fields of information and communication devices but also in the automotive sector. In the automotive sector, safety is considered particularly important because it is directly related to human life.

[0003] Recently, all-solid-state batteries in which liquid electrolytes are replaced with solid electrolytes have been proposed. By not using flammable organic dispersion media, all-solid-state batteries can significantly reduce the likelihood of fire or explosion in the event of a short circuit. Therefore, these all-solid-state batteries can offer significantly higher safety compared to lithium-ion batteries that use liquid electrolytes.

[0004] The problem that the present invention aims to solve is to provide an anode with high ionic conductivity and electronic conductivity.

[0005] Another problem that the present invention aims to solve is to provide an all-solid-state battery comprising the anode.

[0006] A positive electrode according to the concept of the present invention comprises: a positive electrode current collector; and a positive electrode active material layer on the positive electrode current collector; wherein the positive electrode active material layer comprises a first positive electrode active material, a second positive electrode active material, and a solid electrolyte, the first positive electrode active material comprises a first composite containing a first lithium sulfide, a metal halide salt, and a first carbon-based conductive material, and the second positive electrode active material comprises Li 7-b PS 6-b Cl b It may be a material formed by combining a compound represented by (0≤b≤2) and a second carbon-based conductive material.

[0007] A solid-state battery according to another concept of the present invention may include: the positive electrode; a negative electrode comprising a negative electrode current collector and a coating layer disposed on the negative electrode current collector; and a solid electrolyte layer disposed between the positive electrode and the negative electrode.

[0008] The anode according to the present invention may have excellent electronic conductivity and ionic conductivity. In addition, an all-solid-state battery including the anode may have improved lifespan characteristics.

[0009] FIG. 1 is a cross-sectional view of an all-solid-state battery according to an exemplary embodiment of the present invention.

[0010] FIG. 2 is a cross-sectional view of an all-solid-state battery according to another exemplary embodiment of the present invention.

[0011] Figure 3 is an enlarged view of region A of Figure 1 and is a schematic diagram exemplarily showing a cross-section of the positive active material layer of an all-solid-state battery.

[0012] FIG. 4 is an enlarged schematic diagram of the first positive active material (11) of FIG. 3.

[0013] Figure 5 is a transmission electron microscope (TEM) image of the second cathode material.

[0014] FIG. 6 is a cross-sectional view of an all-solid-state battery according to an exemplary embodiment of the present invention.

[0015] Figure 7 is a cross-sectional view along the line A-A' of Figure 6.

[0016] FIG. 8 is a cross-sectional view of an all-solid-state battery according to an exemplary embodiment of the present invention.

[0017] FIG. 9 is a cross-sectional view of an all-solid-state battery according to an exemplary embodiment of the present invention.

[0018] FIG. 10 is a cross-sectional view of an all-solid-state battery according to an exemplary embodiment of the present invention.

[0019] In order to fully understand the structure and effects of the present invention, preferred embodiments of the present invention are described with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and various modifications can be made. The description of these embodiments is provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention.

[0020] In this specification, when a component is described as being on another component, it means that it may be formed directly on the other component or that a third component may be interposed between them. Additionally, in the drawings, the thicknesses of the components are exaggerated for the effective description of the technical content. Throughout the specification, parts indicated by the same reference numeral represent the same components.

[0021] The embodiments described herein will be described with reference to cross-sectional and / or plan views, which are exemplary illustrations of the invention. In the drawings, the thicknesses of films and regions are exaggerated for effective description of the technical content. Accordingly, the regions illustrated in the drawings are schematic in nature, and the shapes of the regions illustrated in the drawings are intended to illustrate specific forms of regions of the device and are not intended to limit the scope of the invention. Although terms such as first, second, third, etc., have been used to describe various components in the various embodiments of this specification, these components should not be limited by such terms. These terms are used merely to distinguish one component from another. The embodiments described and illustrated herein also include their complementary embodiments.

[0022] The terms used herein are for describing the embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, 'comprises' and / or 'comprising' do not exclude the presence or addition of one or more other components to the mentioned components.

[0023] In this specification, "combination of these" may mean a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, and a reaction product, etc.

[0024] Unless otherwise defined in this specification, the particle size may be the average particle size. Additionally, the particle size refers to the average particle size (D50), which means the diameter of the particle whose cumulative volume in the particle size distribution is 50% by volume. The average particle size (D50) may be measured by methods widely known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope (TEM) image or a scanning electron microscope (SEM) image. Alternatively, the average particle size (D50) value may be obtained by measuring using a measuring device utilizing dynamic light scattering, performing data analysis to count the number of particles for each particle size range, and then calculating from this. Alternatively, it may be measured using a laser diffraction method. When measuring by laser diffraction, more specifically, after dispersing the particles to be measured in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasound of about 28 kHz at an output of 60 W, and then the average particle size (D50) at 50% of the particle size distribution in the measuring device can be calculated.

[0025] In this specification, “metal” includes both metals and metalloids such as silicon and germanium in an elemental or ionic state.

[0026] In this specification, “alloy” means a mixture of two or more metals.

[0027] In this specification, “electrode active material” refers to an electrode material capable of undergoing lithiation and delithiation.

[0028] In this specification, “anode active material” refers to an anode material capable of undergoing lithiation and delithiation.

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

[0030] In this specification, “lithiation” and “to lithiate” refer to the process of adding lithium to an electrode active material.

[0031] In this specification, “delithiation” and “to delithiate” refer to the process of removing lithium from an electrode active material.

[0032] In this specification, “charge” and “to charge” refer to the process of providing electrochemical energy to a battery.

[0033] In this specification, “discharge” and “discharge” refer to the process of removing electrochemical energy from a battery.

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

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

[0036] All-solid-state battery (10)

[0037] FIGS. 1 and FIGS. 2 are cross-sectional views of an all-solid-state battery according to an exemplary embodiment of the present invention.

[0038] Referring to FIG. 1, an all-solid-state battery (10) according to one embodiment includes a positive electrode layer (100), a negative electrode layer (200) facing the positive electrode layer (100), and a solid electrolyte layer (300) disposed between the positive electrode layer (100) and the negative electrode layer (200). However, the all-solid-state battery (10) may further include an additional functional layer, such as an adhesion-enhancing layer, disposed between the positive electrode layer (100) and the solid electrolyte layer (300) or between the negative electrode layer (200) and the solid electrolyte layer (300).

[0039] Referring to FIG. 2, an all-solid-state battery (10) according to one embodiment may further include a lithium metal layer (230) disposed between a negative electrode current collector (210) and a coating layer (220) by charging.

[0040] FIG. 6 is a plan view of an all-solid-state battery according to an exemplary embodiment of the present invention. FIG. 7 is a cross-sectional view along line A-A' of FIG. 6. FIGS. 8 to 10 are each cross-sectional views of an all-solid-state battery according to another exemplary embodiment of the present invention.

[0041] anode layer (100)

[0042] Referring to FIG. 1, the positive layer (100) of one embodiment includes a positive current collector (110) and a positive active material layer (120) disposed on the positive current collector (110).

[0043] Figure 3 is an enlarged view of region A of Figure 1, which is a cross-sectional view of the positive active material layer (120).

[0044] Referring to FIG. 3, the positive active material layer (120) may include a first positive active material (11), a second positive active material (12), and a solid electrolyte (20). The positive active material layer (120) may further include a binder (not shown).

[0045] The positive current collector (110) can provide a reference surface on which the positive active material layer (120) is placed. The positive current collector (110) may include, for example, a plate or foil comprising indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

[0046] The thickness of the positive current collector (110) may be, for example, 1 μm to 100 μm, 1 μm to 50 μm, 5 μm to 25 μm, or 10 μm to 20 μm.

[0047] Although not illustrated, a carbon layer with a thickness of 0.1 μm to 4 μm may be further disposed between the positive current collector (110) and the positive active material layer (120) to increase the bonding strength between the positive current collector (110) and the positive active material layer (120).

[0048] The positive current collector (110) 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.

[0049] The base film may be, for example, an insulator. Since the base film contains an insulating thermoplastic polymer, the base film may soften or liquefy upon the occurrence of a short circuit, thereby interrupting battery operation and suppressing a sudden increase in current.

[0050] 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 alloys thereof. The metal layer may act as an electrochemical fuse and cut off in the event of an overcurrent to perform a short-circuit prevention function. The limit current and maximum current can be controlled by adjusting the thickness of the metal layer. The metal layer may be plated or deposited on a base film. As the thickness of the metal layer decreases, the limit current and / or maximum current of the positive current collector (110) decreases, thereby improving the stability of the lithium battery in the event of a short circuit.

[0051] A lead tab may be added to the metal layer for external connection. The lead tab may 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 metal layer melt, allowing the metal layer to be electrically connected to the lead tab.

[0052] To make the weld between the metal layer and the lead tab more robust, a metal chip may be added between the metal layer and the lead tab. The metal chip may be a thin sheet of the same material as the metal of the metal layer. The metal chip may be, for example, metal foil, metal mesh, etc. The metal chip may be, for example, aluminum foil, copper foil, SUS foil, etc. The lead tab may be welded to a metal chip / metal layer laminate or a metal chip / metal layer / base film laminate by placing the metal chip on the metal layer and then welding it to the lead tab. During welding, as the base film, metal layer, and / or metal chip melt, the metal layer or the metal layer / metal chip laminate may be electrically connected to the lead tab. A metal chip and / or lead tab may be added to a portion of the metal layer.

[0053] The thickness of the base film may be, for example, 1 to 50 μm, 1.5 to 50 μm, 1.5 to 40 μm, or 1 to 30 μm. By having the base film within this thickness range, the weight of the electrode assembly can be reduced more effectively. The melting point of the base film may be, for example, 100 to 300 °C, 100 to 250 °C or lower, or 100 to 200 °C. By having the base film within this melting point range, the base film can melt during the welding process of the lead tab and be easily bonded to the lead tab. Surface treatments, such as corona treatment, may be performed on the base film to improve the adhesion between the base film and the metal layer.

[0054] 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. By having the metal layer within this range of thickness, the stability of the electrode assembly can be ensured while maintaining conductivity. The thickness of the metal piece may be, for example, 2 to 10 μm, 2 to 7 μm, or 4 to 6 μm. By having the metal piece within this range of thickness, the connection between the metal layer and the lead tab can be performed more easily. Since the positive current collector (110) has a laminated structure of the base film and the metal layer described above, the weight of the positive layer (100) can be reduced, and consequently, the energy density of the all-solid-state battery (10) can be improved.

[0055] First positive active material (11) and second positive active material (12)

[0056] In this specification, “anode active material” may be used to mean including the first anode active material (11) and the second anode active material (12). For example, “total content of anode active material” may mean the sum of the content of the first anode active material (11) and the content of the second anode active material (12). An anode active material may mean a material capable of reversibly absorbing and desorbing lithium ions.

[0057] Referring to FIG. 3, the positive active material layer (120) may include a first positive active material (11), a second positive active material (12), and a solid electrolyte (20). The positive active material layer (120) may further include a binder (not shown).

[0058] FIG. 4 is an enlarged schematic diagram of the first positive active material (11) of FIG. 3. Referring to FIG. 4, the first positive active material (11) may include a first lithium sulfide (LS), a metal halide salt (MS), and a carbon-based conductive material (CA1). The first positive active material (11) may include a first composite containing the first lithium sulfide (LS), the metal halide salt (MS), and the carbon-based conductive material (CA1).

[0059] The first composite may refer to particles comprising a first lithium sulfide (LS), a metal halide salt (MH), and a carbon-based conductive material (CA1). The first composite may be particles in which the first lithium sulfide (LS), the metal halide salt (MH), and the carbon-based conductive material (CA1) are mixed. The first composite may be particles of various shapes, such as spherical, elliptical, plate-like, or rod-like, but is not limited to the shapes of the particles described above.

[0060] In the first composite, the first lithium sulfide (LS), the metal halide salt (MH), and the carbon-based conductive material (CA1) can each maintain their unique properties. The first lithium sulfide (LS) can have the effect of increasing the energy density of the first positive active material (11). The metal halide salt (MH) can have the effect of increasing the ionic conductivity of the first positive active material (11). The carbon-based conductive material (CA1) can have the effect of increasing the electron conductivity of the first positive active material (11).

[0061] The first composite can be manufactured by mixing the first lithium sulfide (LS), the metal halide salt (MH), and the carbon-based conductive material (CA1), followed by mechanical milling using a ball mill or the like. The first composite can be manufactured by mechanically milling the first lithium sulfide (LS) and the metal halide salt (MH) using a ball mill, and then adding the carbon-based conductive material (CA1) and milling again. However, the above method is not limited to any method that can form a composite by mixing the first lithium sulfide (LS), the metal halide salt (MH), and the carbon-based conductive material (CA1).

[0062] Lithium sulfide (LS) is Li2S n It may include at least one of (1 ≤ n ≤ 8, where n is an integer). The first lithium sulfide (LS) may undergo a continuous reduction reaction. For example, through a continuous reduction reaction of sulfur, the reaction process of lithium polysulfide and lithium sulfide can be expressed as Li2S8 → Li2S6 → Li2S4 → Li2S2 → Li2S, etc. In this process, lithium ions move between the anode and cathode, and at the same time, electrons move through an external circuit to generate an electric current.

[0063] The positive active material layer (100) can improve capacity by including a first lithium sulfide (LS). The first lithium sulfide (LS) may be one of the lithium sources of the all-solid-state battery (10). Through a continuous oxidation / reduction reaction of the first lithium sulfide (LS), lithium ions can move between the positive and negative electrodes, and at the same time, electrons can move through an external circuit to generate current. When a sulfide-based material is used as the positive electrode, the lithium sulfide can act as a lithium source, so the provision of a lithium source at the negative electrode can be omitted. That is, by including a lithium-containing sulfide in the positive electrode, a negative electrode structure with lithium omitted at the negative electrode can be introduced, and the energy density of the battery can be improved.

[0064] Metal halide salts (MS) can improve ion conductivity. Metal halide salts may refer to compounds composed of a metal element and a halogen element. Metal halide salts may be used interchangeably with metal halides. Metal halide salts (MS) may contain one or more types of metal halide salts.

[0065] The metals of the metal halide salts (MS) may include, for example, lithium (Li), aluminum (Al), iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), copper (Cu), titanium (Ti), vanadium (V), chromium (Cr), molybdenum (Mo), silver (Ag), tin (Sn), zinc (Zn), gallium (Ga), indium (In), and thallium (Tl), but are not limited thereto as long as they are metals capable of forming metal halides.

[0066] Metal halide salts (MS) may include, for example, at least one of alkali metal halide salts, alkaline earth metal halide salts, transition metal halide salts, boron group metal halide salts, carbon group metal halide salts, or combinations thereof.

[0067] The halogen elements of the metal halide salt (MS) may include, for example, fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and combinations thereof.

[0068] Alkali metal halide salts may refer to metal halide salts containing alkali metals. The alkali metals of alkali metal halide salts may include, for example, lithium (Li), sodium (Na), potassium (K), etc. Alkali metal halide salts may include, for example, lithium halide salts.

[0069] Lithium halide salts may refer to compounds formed by the combination of lithium and a halogen element. Lithium halide salts may include, for example, at least one of LiF, LiCl, LiBr, LiI, LiAlF4, LiMgCl3, Li2CaBr4, LiKCl2, or a combination thereof.

[0070] Boron group metal halide salts may refer to compounds containing boron group elements (Group 13 elements) and halogen elements. The boron group metal elements of boron group metal halide salts may include aluminum (Al), gallium (Ga), indium (In), and thallium (Tl). Examples of boron group metal halide salts include AlF3, AlCl3, AlBr3, AlI3, GaF3, GaCl3, GaBr3, GaI3, InF3, InCl3, lnBr3, lnI3, TlF3, TlCl3, TlBr3, and TlI 3, Or it may include at least one combination of these. Boron group metal halide salts may include, for example, aluminum halide salts.

[0071] Aluminum halide salts can refer to compounds containing aluminum and halogen elements. Examples of aluminum halide salts include AlCl3, AlF3, AlBr3, and AlI 3, Or it may include at least one combination of these.

[0072] The metal halide salt (MH) may include an alkali metal halide salt, a boron group metal halide salt, or a combination thereof. The metal halide salt (MH) may include, for example, an alkali metal halide salt, a boron group metal halide salt, or a combination thereof. The metal halide salt (MH) can increase ion conductivity and decrease interfacial resistance in the first positive active material (11).

[0073] In one embodiment, the metal halide salt (MS) may include an alkali metal halide salt and a boron group metal halide salt. In one embodiment, the first positive active material (11) may use LiI and AlI3 as the metal halide salt (MH).

[0074] The first carbon-based conductive material (CA1) may refer to a conductive material containing carbon atoms. The first carbon-based conductive material (CA1) may include, for example, crystalline carbon, amorphous carbon, or a combination thereof. The first carbon-based conductive material (CA1) may include at least one of carbon black, acetylene black, furnace black, ketjen black, activated carbon, carbon nanotubes (CNT), carbon nanofibers (CNF), carbon nanobelts, carbon nanorods, graphene, or a combination thereof.

[0075] The first carbon-based conductive material (CA1) may include, for example, a carbon nanostructure. The carbon nanostructure may include a one-dimensional carbon nanostructure, a two-dimensional carbon nanostructure, a three-dimensional carbon nanostructure, or a combination thereof. The carbon nanostructure may include, for example, at least one of carbon nanotubes (CNT), carbon nanofibers (CNF), carbon nanobelts, carbon nanorods, graphene, or a combination thereof. By including the first carbon-based conductive material (CA1), the first positive active material (11) can increase electronic conductivity and improve the cycle characteristics of the battery.

[0076] The first positive active material (11) may have excellent ionic conductivity. The ionic conductivity of the first positive active material (11) according to one embodiment is, for example, 2.0 x 10⁻⁶ at 45°C. -6 S / cm or greater, or 2.5 x 10 -6 It may be greater than S / cm. The ionic conductivity of the first positive active material (11) is, for example, 2.0 x 10 at 45 ℃. -6S / cm to 8.5 x 10 -6 S / cm, or 2.5 x 10 -6 S / cm to 8.0 x 10 -6 It can be S / cm. Ionic conductivity can be measured using the DC polarization method. Alternatively, ionic conductivity can be measured using the complex impedance method.

[0077] The first positive active material (11) may have excellent electron conductivity. The electron conductivity of the first positive active material (11) according to one embodiment is, for example, 4.0 x 10⁻⁶ at 45°C. -3 S / cm, or 4.5 x 10 -3 It may be greater than S / cm. The electron conductivity of the first positive active material (11) is, for example, 4.0 x 10 at 45 ℃. -3 S / cm to 2.5 x 10 -2 S / cm, or 4.5 x 10 -3 S / cm to 2.0 x 10 -2 It may be S / cm. Electronic conductivity can be measured using impedance spectroscopy, but is not limited to any method that a person skilled in the art can select.

[0078] The average particle size (D50) of the first positive active material (11) may be, for example, 3 μm to 10 μm, or 4 μm to 9 μm. If the average particle size (D50) of the first positive active material (11) exceeds the above range, the surface area of ​​the first positive active material (11) decreases, thereby reducing charge / discharge efficiency and structural stability.

[0079] The above average particle size (D50) may refer to the diameter of a particle whose cumulative volume in the particle size distribution is 50 volume%. The average particle size (D50) can be measured using scanning electron microscope images, but is not limited to any method that can be selected by a person skilled in the art.

[0080] The weight ratio of the first lithium sulfide (LS) and the metal halide salt (MS) in the first positive electrode active material (11) may be, for example, 1:1 to 5:1, 1:1 to 4:1, or 1:1 to 3:1. If the weight ratio of the first lithium sulfide (LS) and the metal halide salt (MS) falls outside the above range, the energy density may decrease or the ion conductivity may decrease.

[0081] The content of the first lithium sulfide (LS) in the first positive active material (11) may be, for example, 20% to 80% by weight, 25% to 75% by weight, 30% to 70% by weight, 35% to 65% by weight, 40% to 65% by weight, 45% to 65% by weight, or 45% to 60% by weight of the total weight of the first positive active material (11). If the content of the first lithium sulfide (LS) is less than the above range, the capacity of the all-solid-state battery may be reduced. If the content of the first lithium sulfide (LS) exceeds the above range, the electrical conductivity and ionic conductivity of the first positive active material (11) may be reduced.

[0082] The content of the metal halide salt (MH) in the first positive active material (11) may be, for example, 10% to 50% by weight, 15% to 45% by weight, 15% to 40% by weight, 15% to 35% by weight, or 20% to 35% by weight of the total weight of the first positive active material (11). If the content of the metal halide salt (MH) is less than the above range, the ion conductivity of the first positive active material (11) may decrease. If the content of the metal halide salt (MH) exceeds the above range, the content of the first lithium sulfide (LS) is relatively reduced, and the capacity of the all-solid-state battery may decrease.

[0083] The content of the first carbon-based conductive material (CA1) in the first positive active material (11) may be, for example, 1% to 30% by weight, 5% to 30% by weight, 5% to 25% by weight, or 10% to 25% by weight of the total weight of the first positive active material (11). If the content of the first carbon-based conductive material (CA1) is less than the above range, the electronic conductivity may decrease. If the content of the first carbon-based conductive material (CA1) exceeds the above range, the content of the first lithium sulfide (LS) or metal halide salt (MS) decreases relatively, and the energy density or ion conductivity may decrease.

[0084] According to one embodiment, the positive active material (10) may comprise 40 to 90 parts by weight per 100 parts by weight of the positive active material layer (120). For example, according to one embodiment, the positive active material (10) may comprise 50 to 85 parts by weight, 60 to 80 parts by weight, or 65 to 75 parts by weight per 100 parts by weight of the positive active material layer (120). When satisfying the above ranges, the secondary battery according to one embodiment may have excellent capacity characteristics.

[0085] The second positive active material (12) is Li 7-b PS 6-b Cl bIt may be a material formed by combining a compound represented by (0≤b≤2) and a second carbon-based conductive material. The second positive active material (12) is Li 7-b PS 6-b Cl b It may be a material in which physicochemical modification is performed as a compound represented by (0≤b≤2) and a second carbon-based conductive material are composited with each other. Li 7-b PS 6-b Cl b The compound and the second carbon-based conductive material represented by (0≤b≤2) may be precursors of the second positive active material (12). The second positive active material (12) is Li 7-b PS 6-b Cl b A compound represented by (0≤b≤2) and a second carbon-based conductive material are combined, so that the crystal structure and chemical bonds of the existing precursor can be modified. On the second positive active material (12), Li used as a precursor 7-b PS 6-b Cl b Compounds represented by (0≤b≤2) may not exist as they are.

[0086] Li 7-b PS 6-b Cl b A compound represented by (0≤b≤2) may be a precursor of the second positive active material (12). Li 7-b PS 6-b Cl b Compounds represented by (0≤b≤2) may be argyrodite-type compounds. Li 7-b PS 6-b Cl b Compounds represented by (0≤b≤2) may include, for example, Li6PS5Cl.

[0087] The second carbon-based conductive material can be used in the manufacture of the second positive active material (12). The second carbon-based conductive material may refer to a conductive material containing carbon atoms. For example, the second carbon-based conductive material may be in a state where it is physically mixed with other compound particles. The carbon atoms of the second carbon-based conductive material may be in a state where they have combined with Li, P, S, or Cl atoms to form a new compound.

[0088] The second carbon-based conductive material may include crystalline carbon, amorphous carbon, or a combination thereof. The second carbon-based conductive material may include, for example, at least one of carbon black, acetylene black, furnace black, ketjen black, activated carbon, carbon nanotubes (CNT), carbon nanofibers (CNF), carbon nanobelts, carbon nanorods, graphene, or a combination thereof. The second carbon-based conductive material may be the same as or different from the first carbon-based conductive material (CA1).

[0089] The second positive active material (12) is Li 7-b PS 6-b Cl b Carbon can be coated on the surface by combining a compound represented by (0≤b≤2) and a second carbon-based conductive material. The carbon coating formed on the surface of the second positive active material (12) may be irregular. The carbon coating formed on the surface of the second positive active material (12) may be partially present. The carbon coating formed on the surface of the second positive active material (12) can be verified using a transmission electron microscope or the like.

[0090] In one embodiment, referring to FIG. 5, a projection electron microscope image of a cross-section of the second positive active material (12) can be seen. As shown in FIG. 5, the second positive active material (12) has an irregular and discontinuous carbon coating on its surface.

[0091] The carbon thickness on the surface of the second positive active material (12) may be non-uniform. The carbon thickness may be, for example, 1 nm to 10 nm. The carbon thickness can be verified through electron microscope images, and the average thickness can be obtained by taking multiple cross-sections. In addition, the thickness measurement method is not limited as long as it is a general method that can be selected by a person skilled in the art.

[0092] The second positive active material (12) may further include Li2S. The Li2S on the second positive active material (12) is Li 7-b PS 6-b Cl b It may be a material generated during the process of compounding a compound represented by (0≤b≤2) and a second carbon-based conductive material.

[0093] Li2S on the second positive active material (12) can be one of the lithium sources of the all-solid-state battery (10). Through the Li2S oxidation / reduction reaction, lithium ions can move between the positive and negative electrodes, and at the same time, electrons can move through an external circuit to generate current.

[0094] Li, which is a precursor of the second positive active material (12). 7-b PS 6-b Cl b A compound represented by (0≤b≤2) cannot allow lithium ions to escape during battery operation, even if it exists in the positive electrode active material layer. In other words, it cannot be used as a lithium source. However, in the case of the second positive electrode active material (12), Li 7-b PS 6-b Cl b In the process of compounding a compound represented by (0≤b≤2) and a second carbon-based conductive material, Li2S can be formed through physicochemical changes. Li2S can be used as a lithium source for an all-solid-state battery. Li2S can be used as a lithium source for an all-solid-state battery together with the first lithium sulfide (LS) of the first positive electrode active material (11).

[0095] The presence of Li2S in the second cathode active material can be confirmed, for example, through X-ray diffraction analysis (XRD) using an X-ray diffraction apparatus with CuKα1 rays or X-ray photoelectron spectroscopy (XPS). However, the method is not limited to any other methods that can be ordinarily used by a person skilled in the art.

[0096] The average particle size (D50) of the second positive active material (12) may be, for example, 1 μm to 10 μm, or 2 μm to 8 μm. If the average particle size (D50) of the second positive active material (12) exceeds the above range, the surface area of ​​the second positive active material (12) decreases, which may reduce charge / discharge efficiency and decrease structural stability. The method of measuring the average particle size (D50) of the second positive active material (12) may be the same as the method of measuring the average particle size (D50) of the first positive active material (11), but is not limited to any method that can be easily selected by a person skilled in the art.

[0097] The second positive active material (12) is Li 7-b PS 6-b Cl b A compound represented by (0≤b≤2) and a second carbon-based conductive material can be formed by combining them. At this time, the combination may include both physical mixing and chemical bonding. Through this combination process, the second positive active material (12) can be manufactured as a highly conductive material containing a lithium source that can contribute to the capacity of the all-solid-state battery (10).

[0098] The second positive active material (12) is Li 7-b PS 6-b Cl bA compound represented by (0≤b≤2) and a second carbon-based conductive material can be mixed in, for example, a ratio of 3:1 to 7:1 or 4:1 to 6:1 and then composited. Methods of composite formation may include ball milling, a Spex mill, a Novilta mixer, hybridization, a Henschel mixer, a blade mill, etc.

[0099] The second positive active material (12) may have excellent ionic conductivity. The ionic conductivity of the second positive active material (12) according to one embodiment is, for example, 1.0 x 10 at 45°C. -5 It can be greater than S / cm. Ionic conductivity can be measured using the DC polarization method. Alternatively, ionic conductivity can be measured using the complex impedance method.

[0100] The second positive active material (12) may have excellent electron conductivity. The electron conductivity of the second positive active material (12) according to one embodiment is 0.5 x 10 at 45 ℃. -2 It may be greater than S / cm. Electronic conductivity can be measured using impedance spectroscopy or the DC polarization method, but is not limited to any method selectable by a person skilled in the art.

[0101] By using the first positive active material (11) and the second positive active material (12) in the positive active material layer (120), a battery with excellent capacity and excellent ion conductivity and electron conductivity can be realized.

[0102] The first positive active material (11) can be used to increase energy density within the battery by including the first lithium sulfide (LS) to exhibit high capacity. Additionally, the first positive active material (11) can improve electronic conductivity by including the first carbon-based conductive material (CA1). However, if the content of the first positive active material (11) in the positive active material layer (120) is increased, a decrease in the content of other components is inevitable, so the content of the solid electrolyte (20), etc., may be reduced.

[0103] Therefore, when the first positive active material (11) is used in excess in the positive active material layer (120) to achieve high capacity, a battery with excellent capacity can be secured, but the ion conductivity is reduced, and consequently, the lifespan and efficiency of the battery may be somewhat reduced.

[0104] The second positive active material (12) can contribute to an increase in capacity by including Li2S, and can also perform the role of a solid electrolyte to some extent due to its excellent ion conductivity. That is, when the second positive active material (12) is used in the positive active material layer (120), the content of the solid electrolyte can be reduced and the capacity can be increased.

[0105] That is, by using the first positive active material (11) and the second positive active material (12) together, a battery having a higher capacity and superior conductivity can be manufactured compared to when each is used alone. In addition, by using the first positive active material (11) and the second positive active material (12) together, the content of the positive active material in the positive active material layer (120) can be increased and the content of the solid electrolyte (20) can be reduced, thereby realizing a battery with high energy density.

[0106] The weight ratio of the first positive active material (11) and the second positive active material (12) within the positive active material layer (120) may be, for example, 5:1 to 40:1, 5:1 to 30:1, or 5:1 to 20:1. Since the capacity of the first positive active material (11) is higher than the capacity of the second positive active material (12), the capacity may decrease if the amount of the first positive active material is reduced. If the amount of the second positive active material (12) is excessive, the ion conductivity may decrease.

[0107] The content of the second positive active material (12) in the positive active material layer (120) may be, for example, 1% to 25% by weight of the total weight of the positive active material layer (120). If the content of the second positive active material (12) exceeds the range, the efficiency characteristics of the battery may be reduced. If the content of the second positive active material (12) is less than the range, the capacity may be reduced.

[0108]

[0109] solid electrolyte (20)

[0110] The positive active material layer (120) may include a solid electrolyte (20). The solid electrolyte (20) may be any material used as an ion-conducting material in the art, for example. The solid electrolyte (20) may be, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a combination thereof.

[0111] The solid electrolyte (20) in the positive active material layer (120) may have an average particle size (D50) smaller than that of the solid electrolyte in the solid electrolyte layer (300). For example, the average particle size of the solid electrolyte (20) in the positive active material layer (120) may be 100% or less, 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 particle size of the solid electrolyte in the solid electrolyte layer (300).

[0112] The solid electrolyte (20) may include a sulfide-based solid electrolyte with excellent lithium ion conductivity characteristics. The sulfide-based solid electrolyte is, for example, Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m, n are positive numbers, uppercase “Z” is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, uppercase “M” is one of P, Si, Ge, B, Al, Ga, In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may include at least one selected from (0≤x≤2).

[0113] Sulfide-based solid electrolytes may include, for example, an argyrodite-type solid electrolyte represented by the following chemical formula 1:

[0114] <Chemical Formula 1>

[0115] Li + 12-n-x A n+ X 2- 6-x Y - x

[0116] In the above formula, 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.

[0117] Sulfide-based solid electrolytes are, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may be an argyrodite-type compound comprising one or more selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0118] Alternatively, sulfide-based solid electrolytes are Li 7-a M a PS 6-c X cIt may be an argyrodite-type compound containing (0≤a≤2, (0≤c≤2)). Here, X may be F, Br, Cl, or a combination thereof. M can be scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof. there is.

[0119] The density of the azyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. By having a density of 1.5 g / cc or higher for the azyrodite-type solid electrolyte, the internal resistance of the all-solid-state battery is reduced, and defects such as penetration and short circuit of the solid electrolyte film due to lithium dendrite formation can be prevented. The elastic modulus of the solid electrolyte may be, for example, 15 GPa to 35 GPa.

[0120]

[0121] The solid electrolyte (20) in the positive electrode active material (11, 12) may be the same as or different from the solid electrolyte in the solid electrolyte layer (300).

[0122] The solid electrolyte (20) included in the positive electrode active material layer (120) may have the same average particle size (D50) as the solid electrolyte included in the solid electrolyte layer (300). The solid electrolyte (20) included in the positive electrode active material layer (120) may have a smaller average particle size (D50) compared to the solid electrolyte included in the solid electrolyte layer (300). For example, the average particle size (D50) of the solid electrolyte (20) included in the positive electrode active material layer (120) 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 particle size (D50) of the solid electrolyte included in the solid electrolyte layer (300). Meanwhile, the median average particle size (D50) may be the median diameter measured using a laser particle size distribution meter.

[0123] The content of the solid electrolyte (20) in the positive active material layer (120) may be, for example, 5% to 40% by weight, 5% to 35% by weight, or 5% to 30% by weight of the total weight of the positive active material layer. When the positive active material is increased to increase energy density in an all-solid-state battery, the content of the solid electrolyte (20) in the positive active material layer (120) must inevitably decrease. In one embodiment of the present invention, even if the content of the solid electrolyte (20) in the positive active material layer (120) of the all-solid-state battery is reduced, it can be confirmed that the ion conductivity is supplemented by the positive active material (11, 12).

[0124] The positive active material layer (120) may further include, in addition to the first positive active material (11), second positive active material (12), and solid electrolyte (20) described above, additives such as a binder, conductive material, filler, coating agent, dispersant, and ion conductivity aid.

[0125] The positive active material layer (120) may further include a conductive material. The conductive material may have conductivity without causing chemical changes in the all-solid-state battery (10), thereby increasing the conductivity of the positive active material and the solid electrolyte. The conductive material may include any conductive material used in the art without limitation. The conductive material may be, for example, a carbon-based material, a metal-based material, or a combination thereof.

[0126] The metal-based material may be metal powder, metal fiber, or a combination thereof, but is not limited to these, and any metal-based material used as a conductive material in the relevant technical field is possible. The carbon-based material may include crystalline carbon, amorphous carbon, or a combination thereof. The carbon-based material may include, for example, one or more selected from graphite, carbon black, acetylene black, carbon nanotubes (CNT), carbon nanofibers (CNF), carbon nanobelts, carbon nanorods, and graphene. The internal resistance of the positive electrode active material layer (120) is reduced by the conductive material, and the cycle characteristics of the secondary battery can be further improved.

[0127] The conductive material in the positive active material layer (120) may be the same as or different from the first carbon-based conductive material (CA1) or the second carbon-based conductive material in the first positive active material (11).

[0128] The content of the conductive material in the positive active material layer (120) may be, for example, 1% to 30% by weight, 1% to 20% by weight, or 1% to 10% by weight of the total weight of the positive active material layer (120). This may be used in the same sense as the content of the conductive material in the positive electrode, and may mean a ratio calculated based on the weight excluding the positive current collector in the positive electrode.

[0129] The positive active material layer (120) may further include a binder (not shown). The binder may include a material for bonding the first positive active material (11), the second positive active material (12), the solid electrolyte (20), etc. included in the positive active material layer (120), and for improving the bonding strength with the positive current collector (110). The binder may be, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene (PTFE), polyvinylidene fluoride, polyethylene, etc., but is not limited to these, and any material used as a binder in the relevant technical field may be used.

[0130] The content of the binder in the positive active material layer (120) may be, for example, 0.1% to 10% by weight, 0.5% to 5% by weight, or 0.5% to 2% by weight of the total weight of the positive active material layer (120). The binder may be omitted. This may be used in the same sense as the content of the binder in the positive, and may mean a ratio calculated based on the weight excluding the positive current collector in the positive.

[0131] FIG. 10 is a cross-sectional view of an all-solid-state battery according to an exemplary embodiment of the present invention. Referring to FIG. 10, the positive layer (100) may further include a positive coating layer (CTL) provided between a positive current collector (110) and a positive active material layer (120). The positive coating layer (CTL) may be disposed directly, for example, on one or both sides of the positive current collector (110). The positive coating layer (CTL) may be coated on one or both sides of the positive current collector (110). No other layer may be disposed between the positive current collector (110) and the positive coating layer (CTL).

[0132] By placing the positive coating layer (CTL) directly on one or both sides of the positive current collector (110), the bonding strength between the positive current collector (110) and the positive active material layer (120) can be further improved. By placing the positive coating layer (CTL) between the positive current collector (110) and the positive active material layer (120), side reactions between the solid electrolyte (20) or the positive active material (11, 12) and the positive current collector (110) can be more effectively suppressed. For example, the positive coating layer (CTL) can prevent corrosion of the sulfide-based positive active material (e.g., Li2S) by the positive current collector (110). Consequently, the positive coating layer (CTL) can suppress the deterioration of the all-solid-state battery (10) during the charging and discharging process and improve cycle characteristics.

[0133] The thickness of the anode coating layer (CTL) 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 anode current collector (110). The thickness of the anode coating layer (CTL) may be, for example, 10 nm to 5 µm, 50 nm to 5 µm, 200 nm to 4 µm, 500 nm to 3 µm, 500 nm to 2 µm, 500 nm to 1.5 µm, or 700 nm to 1.3 µm. By having the anode coating layer (CTL) have a thickness within this range, the bonding strength between the anode current collector (110) and the anode active material layer (120) is further improved, and the increase in interfacial resistance can be suppressed. The thickness of the anode coating layer (CTL) can be measured, for example, from a scanning electron microscope (SEM) image of a cross-section of the anode coating layer (CTL).

[0134] The anode coating layer (CTL) may include, for example, a carbon-based conductive material. The carbon-based conductive material included in the anode coating layer (CTL) may be the same as or different from the carbon-based conductive material (CA1) of the first anode active material (11). Since the anode coating layer (CTL) includes a carbon-based conductive material, the anode coating layer (CTL) may be, for example, a conductive layer.

[0135] The positive coating layer (CTL) may additionally include, for example, a binder. By additionally including a binder in the positive coating layer (CTL), the bonding strength between the positive current collector (110) and the positive active material layer (120) can be further improved. The binder included in the positive coating layer (CTL) is, for example, a conductive binder or a non-conductive binder. The conductive binder is, for example, an ion-conducting binder and / or an electron-conducting binder. A binder having both ion conductivity and electron conductivity may belong to both an ion-conducting binder and an electron-conducting binder.

[0136] The binder included in the anode coating layer (CTL) may be selected from among the binders used in the anode active material layer (120). The anode coating layer (CTL) may include the same binder as the binder used in the anode active material layer (120). The binder included in the anode coating layer (CTL) is, for example, a fluorine-based binder. The fluorine-based binder included in the anode coating layer (CTL) is, for example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or a combination thereof. The anode coating layer (CTL) may be, for example, a binding layer containing a binder. The anode coating layer (CTL) may be, for example, a conductive layer containing a binder and a carbon-based conductive material.

[0137] The anode coating layer (CTL) can be disposed on the anode current collector (110) in a dry or wet manner, for example. The anode coating layer (CTL) can be disposed on the anode current collector (110) in a dry manner by deposition, for example, CVD, PVD, etc. The anode coating layer (CTL) can be disposed on the anode current collector (110) in a wet manner, for example, by spin coating, dip coating, etc. The anode coating layer (CTL) can be disposed on the anode current collector (110) by, for example, depositing a carbon-based conductive material onto a substrate by deposition. The dry-coated anode coating layer (CTL) may be made of a carbon-based conductive material and may not contain a binder. The anode coating layer (CTL) can be disposed on the anode current collector (110) by, for example, coating a composition comprising a carbon-based conductive material, a binder, and a solvent onto the surface of the electrode current collector and drying it. The anode coating layer (CTL) may have a single-layer structure or a multi-layer structure including multiple layers. The multi-story structure can be a 2-story structure, a 3-story structure, a 4-story structure, etc.

[0138]

[0139] solid electrolyte layer (300)

[0140] Referring to FIGS. 1 and 2, the solid electrolyte layer (300) may include a sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics, which is disposed between the anode layer (100) and the cathode layer (200). The solid electrolyte included in the solid electrolyte layer (300) may be the same as or different from any one of the materials that may be included in the solid electrolyte (20) included in the anode active material layer (120) described above.

[0141] In one embodiment, the solid electrolyte layer (300) may include a sulfide-based solid electrolyte. The sulfide-based solid electrolyte may be manufactured by processing starting materials, such as Li2S or P2S5, by a melt quenching method or a mechanical milling method. Additionally, heat treatment may be performed after such processing. The solid electrolyte may be amorphous, crystalline, or a mixture thereof. Furthermore, the solid electrolyte may include sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the sulfide-based solid electrolyte materials described above. For example, the solid electrolyte may be a material containing Li2S-P2S5. When using a sulfide-based solid electrolyte material containing Li2S-P2S5 to form the solid electrolyte, the molar ratio of Li2S and P2S5 is, for example, in the range of Li2S : P2S5 = 50 : 50 to 90 : 10.

[0142] Sulfide-based solid electrolytes are, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may be an argyrodite-type compound comprising one or more selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0143] Alternatively, sulfide-based solid electrolytes are Li 7-a M a PS 6-c X cIt may be an argyrodite-type compound containing (0≤a≤2, (0≤c≤2)). Here, X may be F, Br, Cl, or a combination thereof. M can be scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof. there is.

[0144] The density of the azyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. Since the azyrodite-type solid electrolyte has a density of 1.5 g / cc or higher, the internal resistance of the all-solid-state battery is reduced, and defects such as penetration and short circuit of the solid electrolyte film due to lithium dendrite formation can be prevented. The elastic modulus of the solid electrolyte is, for example, 15 GPa to 35 GPa.

[0145] The solid electrolyte layer (300) may further include a binder. The binder included in the solid electrolyte layer (300) is, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited to these. The binder of the solid electrolyte layer (300) may be the same as or different from the binder included in the positive electrode active material layer (120) or the binder included in the coating layer (220).

[0146] Meanwhile, although not shown, a carbon layer may be further included to improve adhesion between the coating layer (220) and the solid electrolyte layer (300).

[0147] FIG. 6 is a cross-sectional view of an all-solid-state battery according to an exemplary embodiment of the present invention. FIG. 7 is a cross-sectional view along line A-A' of FIG. 6. FIG. 8 to 10 are cross-sectional views of another exemplary all-solid-state battery according to an embodiment of the present invention.

[0148] Referring to FIGS. 6 to 10, the solid electrolyte layer (300) may include a first solid electrolyte layer (310) and a second solid electrolyte layer (320). The first solid electrolyte layer (310) may be adjacent to the anode layer (100), and the second solid electrolyte layer (320) may be adjacent to the cathode layer (200).

[0149] The first solid electrolyte layer (310) may include a first solid electrolyte. The first solid electrolyte may have a particle shape such as a sphere or an ellipsoid. The first solid electrolyte may include a sulfide-based solid electrolyte. The first solid electrolyte may be amorphous, crystalline, or a mixture thereof. Additionally, the solid electrolyte may include sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the sulfide-based solid electrolyte materials described above, for example. For example, the solid electrolyte may be a material containing Li2S-P2S5. When using a sulfide-based solid electrolyte material containing Li2S-P2S5 to form the solid electrolyte, the molar ratio of Li2S and P2S5 may be, for example, in the range of Li2S : P2S5 = 50 : 50 to 90 : 10.

[0150] In one embodiment, the first solid electrolyte is Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li7-x PS 6-x I x It may include an argyrodite-type compound comprising one or more selected from (0≤x≤2). The first solid electrolyte may include an argyrodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0151] In another embodiment, the first solid electrolyte is Li 7-a M a PS 6-c X c It may include an argyrodite-type compound comprising. Here, X may be Cl, Br, or a combination thereof. M may be Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn, or a combination thereof. a and c may each be a real number between 0 and 2.

[0152] The density of the azyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. Since the azyrodite-type solid electrolyte has a density of 1.5 g / cc or higher, the internal resistance of the all-solid-state battery is reduced, and defects such as penetration and short circuit of the solid electrolyte film due to lithium dendrite formation can be prevented. The elastic modulus of the first solid electrolyte is, for example, 15 GPa to 35 GPa.

[0153] The second solid electrolyte layer (320) may include a second solid electrolyte. The second solid electrolyte may have a particle shape such as a sphere or an ellipsoid. The second solid electrolyte may include a sulfide-based solid electrolyte. The description of the second solid electrolyte may be the same or similar as that described above for the first solid electrolyte. In one embodiment, the second solid electrolyte may have substantially the same composition as the first solid electrolyte. In another embodiment, the second solid electrolyte may have a composition similar to that of the first solid electrolyte.

[0154] The second solid electrolyte can come into direct contact with the coating layer (220). By doing so, the second solid electrolyte can suppress lithium dendrites formed between the coating layer (220) and the negative electrode current collector (210). The second solid electrolyte can effectively suppress negative electrode side reactions. This can improve the cell performance of the all-solid-state battery (10) according to the present invention.

[0155] Each of the first and second solid electrolyte layers (310, 320) may further include a binder. The binder in the solid electrolyte layer (300) is, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited to these. The binder in the solid electrolyte layer (300) may be the same as or different from the binder in the positive active material layer (120) or the binder in the coating layer (220).

[0156] The content of the binder in the solid electrolyte layer (300) may be 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 (300).

[0157] In another embodiment of the present invention, the solid electrolyte layer (300) may be provided as a single layer structure rather than a double layer structure of the first solid electrolyte layer (310) and the second solid electrolyte layer (320).

[0158] Referring again to FIGS. 6 to 10, the anode layer (100) and the first solid electrolyte layer (310) can form an anode composite layer (CSH). The cathode layer (200) and the second solid electrolyte layer (320) can form a cathode composite layer (ASH). An anode composite layer (CSH) can be laminated on the cathode composite layer (ASH).

[0159] The area of ​​the cathode composite layer (ASH) and the area of ​​the anode composite layer (CSH) may differ from each other. Specifically, the area of ​​the cathode composite layer (ASH) may be larger than the area of ​​the anode composite layer (CSH). The anode composite layer (CSH) may completely overlap within the cathode composite layer (ASH).

[0160] In one embodiment of the present invention, the first solid electrolyte layer (310) may have substantially the same area as the anode layer (100). The second solid electrolyte layer (320) may have substantially the same area as the cathode layer (200).

[0161] The positive composite layer (CSH) may have a first width (WI1) in the first direction (D1). The negative composite layer (ASH) may have a second width (WI2) in the first direction (D1). The first width (WI1) may be smaller than the second width (WI2). The positive composite layer (CSH) may have a third width (WI3) in the second direction (D2). The negative composite layer (ASH) may have a fourth width (WI4) in the second direction (D2). The third width (WI3) may be smaller than the fourth width (WI4).

[0162] The all-solid-state battery (10) according to the present embodiment can be manufactured by forming a negative electrode composite layer (ASH) on a first carrier film and forming a positive electrode composite layer (CSH) on a second carrier film, and then laminating the negative electrode composite layer (ASH) and the positive electrode composite layer (CSH).

[0163] In one embodiment, as shown in FIG. 7, the positive active material layer (120) in a discharged state may have a first thickness (TK1). The all-solid-state battery (10) may have a first height (HE1) in a third direction (D3). The first height (HE1) may be the sum of the thickness of the positive composite layer (CSH) and the thickness of the negative composite layer (ASH).

[0164] FIG. 9 is a cross-sectional view along line A-A' of FIG. 6, intended to illustrate an all-solid-state battery according to another embodiment of the present invention. Referring to FIG. 9, the all-solid-state battery (10) according to the present embodiment may further include a gasket (GSK). The gasket (GSK) may be provided to surround the positive electrode composite layer (CSH). The gasket (GSK) may fill the step difference on the side of the all-solid-state battery (10) caused by the difference in area between the negative electrode composite layer (ASH) and the positive electrode composite layer (CSH). The gasket (GSK) may surround the four sides of the positive electrode composite layer (CSH). For example, the thickness of the gasket (GSK) may be substantially the same as the thickness of the positive electrode composite layer (CSH).

[0165] The upper surface of the second solid electrolyte layer (320) may include a first region in contact with the first solid electrolyte layer (310) and a second region in contact with the gasket (GSK). The second region may be a peripheral region of the upper surface of the second solid electrolyte layer (320). The second region may surround the first region.

[0166] The gasket (GSK) can prevent cracking of the solid electrolyte layer (300) during the manufacturing of the all-solid-state battery (10) and / or during the charging and discharging of the all-solid-state battery (10). This can improve the cycle characteristics of the all-solid-state battery (10). If the all-solid-state battery (10) does not include the gasket (GSK), uneven pressure is applied to the negative electrode composite layer (ASH) in contact with the positive electrode composite layer (CSH), causing cracking in the solid electrolyte layer (300), and the likelihood of a short circuit occurring due to the growth of lithium metal through this may increase.

[0167] The thickness of the gasket (GSK) may be greater than the thickness of the positive composite layer (CSH) or substantially equal to the thickness of the positive composite layer (CSH). Since the thickness of the gasket (GSK) is equal to the thickness of the positive composite layer (CSH), a uniform pressure is applied between the positive composite layer (CSH) and the negative composite layer (ASH), and the positive composite layer (CSH) and the negative composite layer (ASH) are sufficiently in contact, thereby reducing the interfacial resistance between the first solid electrolyte layer (310) and the second solid electrolyte layer (320). Additionally, the internal resistance of the solid electrolyte layer (300) may be reduced as the solid electrolyte layer (300) is sufficiently sintered during the pressurized manufacturing process of the all-solid-state battery (10).

[0168] The gasket (GSK) may have a single-layer structure, for example. Alternatively, although not shown in the drawings, the gasket (GSK) may have a multi-layer structure. In a gasket (GSK) having a multi-layer structure, each layer may have a different composition. A gasket (GSK) 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. A gasket (GSK) having a multi-layer structure may include, for example, one or more adhesive layers and one or more support layers.

[0169] The gasket (GSK) may include, for example, a flame-retardant inert member. By providing flame retardancy, the flame-retardant inert member can prevent thermal runaway and the possibility of ignition of the lithium-sulfur battery (10). Consequently, the gasket (GSK) can further enhance the safety of the all-solid-state battery (10). By absorbing residual moisture within the all-solid-state battery (10), the flame-retardant inert member prevents the deterioration of the all-solid-state battery (10), thereby improving the lifespan characteristics of the all-solid-state battery (10).

[0170]

[0171] cathode layer (200)

[0172] Referring to FIG. 1, in one embodiment, an all-solid-state battery (10) may include a negative electrode layer (200) comprising a negative electrode current collector (210) and a coating layer (220) disposed on the negative electrode current collector (210).

[0173] The negative electrode layer (200) may include a negative electrode current collector (210) and a coating layer (220) on the negative electrode current collector (210). The negative electrode current collector (210) may provide a reference surface on which the coating layer (220) is placed. The negative electrode current collector (210) may include, for example, a material that does not react with lithium, that is, does not form any alloys or compounds with lithium. For example, the negative electrode current collector (210) may include at least one metal selected from the group consisting of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The thickness of the negative electrode current collector (210) may be 1 μm to 20 μm, more specifically 5 μm to 15 μm, and more specifically 7 μm to 10 μm.

[0174] The negative current collector (210) may be composed of one of the metals described above, or may include an alloy of two or more metals or a coating material. The negative current collector (210) may, for example, have a plate-like or foil-like shape. Meanwhile, in one embodiment, the negative current collector (210) may be omitted.

[0175] Although not illustrated, a negative current collector (210) according to one embodiment may include 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. By including an insulating thermoplastic polymer in the base film, the base film may soften or liquefy upon a short circuit, thereby blocking battery operation and suppressing a sudden 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 current collector (210) 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 current collector (210), refer to the positive electrode current collector (110) described above. By having the negative electrode current collector (210) have this structure, the weight of the negative electrode layer (200) can be reduced, and consequently, the energy density of the all-solid-state battery (10) can be improved.

[0176] The coating layer (220) can be configured to allow lithium metal to grow between the all-solid-state battery (10) and the negative current collector (210) during charging. The coating layer (220) can serve as a protective layer for the lithium metal and simultaneously suppress the precipitation and growth of lithium dendrites.

[0177] The coating layer (220) may include metal and carbon. For example, the coating layer (220) may include at least one metal 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 coating layer (220) may include at least one carbon selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene. In one embodiment, the coating layer (220) may include a mixture of carbon black and silver (Ag).

[0178] The coating layer (220) may further include other additives in addition to metal and carbon. The coating layer (220) may further include at least one additive selected from the group consisting of, for example, binders, fillers, coating agents, dispersants, and ion-conducting aids.

[0179] The coating layer (220) may have a smaller thickness compared to the positive active material layer (120). The thickness of the coating layer (220) may be, 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 active material layer (120). The thickness of the coating layer (220) may be, for example, 1 µm to 20 µm, 2 µm to 10 µm, or 3 µm to 7 µm. If the thickness of the coating layer (220) is excessively thin, lithium dendrites formed between the coating layer (220) and the negative current collector (210) may cause the coating layer (220) to collapse, thereby degrading the cycle characteristics of the all-solid-state battery (10). If the thickness of the coating layer (220) increases excessively, the energy density of the all-solid-state battery (10) decreases and the internal resistance of the all-solid-state battery (10) due to the coating layer (220) increases, which may degrade the cycle characteristics of the cell.

[0180] Meanwhile, although not shown, a carbon layer may be further included to improve adhesion between the coating layer (220) and the solid electrolyte layer (300).

[0181] Referring to FIG. 2, an all-solid-state battery (10) according to one embodiment may further include a lithium metal layer (230) disposed between a negative electrode current collector (210) and a coating layer (220) by charging.

[0182] The lithium metal layer (230) may include lithium or a lithium alloy. Since the lithium metal layer (230) is a metal layer containing lithium, it may function as, for example, a lithium reservoir. The lithium alloy may be, 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, but is not limited to these; any alloy used as a lithium alloy in the relevant technical field may be possible. The lithium metal layer (230) may be composed of one of these alloys or lithium, or may be composed of various types of alloys. The lithium metal layer (230) may be, for example, a plated layer. The lithium metal layer (230) may be deposited, for example, between the coating layer (220) and the negative current collector (210) during the charging process of the all-solid-state battery (10).

[0183] Referring to FIG. 8, the lithium metal layer (230) may have a third thickness (TK3). The third thickness (TK3) is not particularly limited, but may be, for example, 1 μm to 500 μm, 1 μm to 200 μm, 1 μm to 150 μm, 1 μm to 100 μm, or 1 μm to 50 μm. If the thickness (TK3) of the lithium metal layer (230) is excessively thin, it may be difficult for the lithium metal layer (230) to perform the role of a lithium reservoir. If the thickness of the lithium metal layer (230) is excessively thick, the mass and volume of the all-solid-state battery (10) increase, and the cycle characteristics of the all-solid-state battery (10) may deteriorate.

[0184] In another embodiment, the lithium metal layer (230) within the negative electrode layer (200) may be provided, for example, between the negative electrode current collector (210) and the coating layer (220) before assembly of the all-solid-state battery (10). When the lithium metal layer (230) is placed between the negative electrode current collector (210) and the coating layer (220) before assembly of the all-solid-state battery (10), the lithium metal layer (230) acts as a lithium reservoir because it is a metal layer containing lithium. For example, a lithium foil may be placed between the negative electrode current collector (210) and the coating layer (220) before assembly of the all-solid-state battery (10).

[0185] When a lithium metal layer (230) is deposited by charging after assembly of the all-solid-state battery (10), the energy density of the all-solid-state battery (10) can be increased because the lithium metal layer (230) is not included during assembly of the all-solid-state battery (10). When charging the all-solid-state battery (10), it can be charged beyond the charging capacity of the coating layer (220). That is, the coating layer (220) is overcharged. At the beginning of charging, lithium can be absorbed in the coating layer (220). When charging beyond the capacity of the coating layer (220), lithium can be deposited, for example, between the coating layer (220) and the negative electrode current collector (210). A lithium metal layer (230) can be formed by the deposited lithium.

[0186] The lithium metal layer (230) can be composed mainly of lithium (i.e., metallic lithium). During discharge, the lithium in the lithium metal layer (230) can be ionized and move to the positive electrode layer (100). In other words, lithium can be used as a negative electrode active material in the all-solid-state battery (10). In addition, since the coating layer (220) covers the lithium metal layer (230), the coating layer (220) can protect the lithium metal layer (230) and simultaneously suppress the precipitation growth of lithium dendrites. Therefore, the coating layer (220) can suppress short circuits and capacity degradation of the all-solid-state battery (10) and improve the cycle characteristics of the all-solid-state battery (10).

[0187] When a lithium metal layer (230) is formed by charging after assembly of the all-solid-state battery (10), the negative electrode layer (200), that is, the negative electrode current collector (210) and the coating layer (220) and the region between them may be a Li-free region that does not contain lithium (Li) in the initial state or after complete discharge of the all-solid-state battery (10).

[0188] Referring to FIG. 8, the positive active material layer (120) from which lithium ions are released by charging of the all-solid-state battery (10) may have a second thickness (TK2). The second thickness (TK2) of the positive active material layer (120) may be smaller than the first thickness (TK1) of FIG. 2.

[0189] In one embodiment of the present invention, the difference between the first thickness (TK1) and the second thickness (TK2) may be substantially the same or similar to the third thickness (TK3) of the lithium metal layer (230). For example, the third thickness (TK3) may be 1.0 to 1.5 times, or 1.0 to 1.2 times, the difference between the first thickness (TK1) and the second thickness (TK2). According to the present invention, the thickness of the positive active material layer (120) may be reduced by the same amount as the thickness of the lithium metal layer (230) formed by charging the all-solid-state battery (10).

[0190] Although not illustrated, the all-solid-state battery (10) may operate (i.e., charge and / or discharge) while pressurized by a pressurizing jig. In one embodiment, the all-solid-state battery (10) may be pressurized to 0.8 MPa to 2 MPa. For example, the all-solid-state battery (10) may have an internal pressure of about 1 MPa when discharged, and the all-solid-state battery (10) may have an internal pressure of about 1.5 MPa when charged. The ratio of the internal pressure of the all-solid-state battery (10) in the charged state of FIG. 9 to the internal pressure of the all-solid-state battery (10) in the discharged state of FIG. 7 may be 1.0 to 2.0, or 1.2 to 1.8.

[0191] The height (or thickness or volume) of the all-solid-state battery (10) may change according to charging and discharging under the aforementioned pressurized state. In the all-solid-state battery (10) according to the present embodiment, the thickness of the positive active material layer (120) may decrease in correspondence with the lithium metal layer (230) formed by charging. Accordingly, the second height (HE2) of the charged all-solid-state battery (10) shown in FIG. 8 may be similar to the first height (HE1) of the discharged lithium-sulfur battery (10) shown in FIG. 7. For example, the second height (HE2) may be 1 to 1.5 times, or 1 to 1.2 times, the first height (HE1).

[0192] FIG. 10 is a cross-sectional view of an all-solid-state battery according to an exemplary embodiment of the present invention. Referring to FIG. 10, the negative electrode layer (200) may further include a thin film (TFL) provided between a negative electrode current collector (210) and a coating layer (220). The thin film (TFL) may be provided on one surface of the negative electrode current collector (210) to form an alloy with lithium.

[0193] The thin film (TFL) may include, for example, an element capable of forming an alloy with lithium. Elements capable of forming an alloy with lithium include, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., but are not necessarily limited to these, and any element capable of forming an alloy with lithium in the relevant technical field is possible. The thin film (TFL) may be composed of one of these metals or may be composed of an alloy of various types of metals.

[0194] By placing the thin film (TFL) on one side of the negative current collector (210), the deposition pattern of the lithium metal layer (230) deposited between, for example, the thin film (TFL) and the coating layer (220) is further flattened, and the cycle characteristics of the all-solid-state battery (10) can be further improved.

[0195] The thickness of the thin film (TFL) may be, 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 (TFL) is less than 1 nm, it may be difficult to perform the function provided by the thin film (TFL). If the thickness of the thin film (TFL) is excessively thick, the thin film (TFL) itself absorbs lithium, and the amount of lithium precipitated in the negative electrode layer (200) decreases, which lowers the energy density of the all-solid-state battery (10) and may lower the cycle characteristics of the all-solid-state battery (10). The thin film (TFL) may be formed on the negative electrode current collector (210) by, for example, vacuum deposition, sputtering, plating, etc., but is not necessarily limited to these methods, and any method capable of forming the thin film (TFL) in the relevant technical field may be possible.

[0196] Although not illustrated, the all-solid-state battery (10) of the present invention may have a plurality of unit cells stacked. The stacked unit cells may include an elastic sheet between adjacent electrodes. For example, an elastic sheet may be included between adjacent first negative electrodes and second negative electrodes. For example, an elastic sheet may be included between adjacent first positive electrodes and second positive electrodes.

[0197] The elastic sheet may include, for example, at least one of polyurethane, natural rubber, spandex, butyl rubber (Isobutylene Isoprene Rubber, IIR), fluoroelastomer, elastomer, ethylene-propylene rubber (EPR), styrene-butadiene rubber (SBR), chloroprene, elastin, rubber epichlorohydrin, nylon, terpene, isoprene rubber, polybutadiene, nitrile rubber, thermoplastic elastomer, silicone rubber, ethylene-propylene-diene rubber (EPDM), ethylene vinyl acetate (EVA), halogenated butyl rubber, neoprene, and copolymers thereof, but is not limited thereto, and any material having elasticity may be used without limitation. The elastic sheet of one embodiment may be made of a urethane-based material, such as polyurethane.

[0198] The elastic sheet may be pressed so that, when installed, its thickness is 40 to 90% of its initial thickness before applying pressure. For example, the elastic sheet may be pressed so that, when installed, its thickness is 50 to 85% of its initial thickness before applying pressure, specifically 60 to 80%, or 65 to 75%. Within the above range, the volume change of the negative electrode can be effectively absorbed to enable smooth charging and discharging of the all-solid-state battery (10).

[0199] The elastic sheet can effectively suppress the change in negative electrode volume of the all-solid-state battery (10) including the coating layer (220) described above.

[0200] The thickness of the elastic sheet can be determined to be in the range of 200 to 500% of the thickness of the coating layer (220) formed during charging of the all-solid-state battery (10) including the coating layer (220). In the all-solid-state battery (10) including the coating layer (220), the thickness of the coating layer (220) is determined in proportion to the current density of the positive electrode. That is, the thickness of the coating layer (220) is determined according to the amount of lithium moving from the positive electrode to the negative electrode, and a change in the volume of the negative electrode occurs as a result. Therefore, the thickness of the elastic sheet can be determined to absorb such a change in the volume of the negative electrode. Accordingly, by setting the thickness of the elastic sheet to be in the range of 200 to 500% of the thickness of the negative electrode coating layer formed during charging of the secondary battery including the negative electrode coating layer, the change in the volume of the negative electrode can be effectively absorbed. For example, the thickness of the elastic sheet may be in the range of 250 to 450% of the thickness of the negative coating layer formed during charging of a secondary battery including a negative coating layer, specifically, for example, in the range of 300 to 400%.

[0201] The thickness of the elastic sheet can be set in the range of, for example, 50 μm to 300 μm, and can be selectively set in some cases, such as, for example, 100 μm to 150 μm, 200 μm to 300 μm, or 50 μm to 100 μm.

[0202]

[0203] The present invention will be explained in more detail below through examples. However, these examples are intended to illustrate the invention and the scope of the invention is not limited to these examples.

[0204]

[0205] Preparation Example 1 - Preparation of First Anode Active Material (Li2S-LiI-AlI3-CNF)

[0206] Li2S, LiI, and AlI3 were mixed in a weight ratio of 40:5:15. The mixture was mechanically milled using a ball mill to prepare a Li2S-LiI-AlI3 composite. The milling conditions were 25 ℃ and 450 rpm for 10 hours. The milling energy applied to the sample during milling was 20 G. The Li2S-LiI-AlI3 composite thus prepared was mixed with carbon nanofiber (CNF) in a weight ratio of 60:10. The mixture was mechanically milled using a ball mill to prepare a Li2S-LiI-AlI3-CNF composite. The milling conditions were 25 ℃ and 450 rpm for 10 hours. The milling energy applied to the sample during milling was 20 G. The Li2S-LiI-AlI3-CNF composite thus prepared was used as the first cathode active material. The diameter of the manufactured particles was 7 μm (D50).

[0207]

[0208] Preparation Example 2 - Preparation of First Anode Active Material (Li2S-LiI-AlI3-CNF)

[0209] The preparation was carried out in the same manner as Preparation Example 1, except that Li2S, LiI, and AlI3 were mixed in a weight ratio of 40:15:5, and the Li2S-LiI-AlI3 composite and carbon nanofiber (CNF) were mixed in a weight ratio of 60:10. The diameter of the prepared particles was 6 μm (D50).

[0210]

[0211] Preparation Example 3 - Preparation of Second Anode Active Material

[0212] Li6PS5Cl and carbon black (Imerys, 40 nm) were mixed in a weight ratio of 85:15 and composited by mechanical milling using a ball mill. Specifically, 5 mm zirconia beads and powder were placed in a zirconia inner-walled container in a weight ratio of 10:1 and ball milled at 150 rpm for 3 hours. The diameter of the manufactured particles was 5 μm (D50).

[0213]

[0214] Preparation Example 4 - Preparation of the second positive electrode active material

[0215] It was prepared in the same manner as in Preparation Example 3, except that Li6PS5Cl and Carbon nanofiber (CNF) (Alfa, diameter 300 nm) were mixed in a weight ratio of 85:15. The diameter of the prepared particles was 6 μm.

[0216]

[0217] Example 1 - Preparation Example 1:Preparation Example 3:Solid Electrolyte = 80:2:18

[0218] (Anode manufacturing)

[0219] A cathode was prepared with a content of 80:2:18 of the first cathode active material of Preparation Example 1, the second cathode active material of Preparation Example 3, and a solid electrolyte. The solid electrolyte used was Li6PS5Cl (D50 = 1.0 μm, crystalline), which is an argyrodite-type crystal.

[0220] PTFE was prepared as a binder. Using these materials, an anode composite was prepared by mixing a first anode active material, a second anode active material, a solid electrolyte, and a binder. The anode composite was obtained by dry mixing using a mixer.

[0221] An anode was prepared by placing the anode composite on one side of an anode current collector made of aluminum foil coated with carbon on one side and plate pressing at a pressure of 200 MPa for 10 minutes. The thickness of the anode was approximately 120 μm. The thickness of the anode active material layer was approximately 100 μm, and the thickness of the carbon-coated aluminum foil was approximately 20 μm. The area of ​​the anode active material layer and the anode current collector were the same.

[0222] (Cathode manufacturing)

[0223] A SUS foil with a thickness of 10 μm was prepared as a cathode current collector. As a metal-carbon composite, carbon black (CB) with a primary particle size of about 30 nm and silver (Ag) particles with an average particle diameter of about 60 nm were prepared.

[0224] 4 g of a mixed powder, prepared by mixing carbon black (CB) and silver (Ag) particles in a weight ratio of 3:1, was placed in a container, and 4 g of an NMP solution containing 7 wt% of a PVDF binder (Kureha # 9300) was added to prepare a mixed solution. A slurry was prepared by stirring the mixed solution while gradually adding NMP to it. The prepared slurry was applied to a SUS sheet using a bar coater, dried in air at 80°C for 10 minutes, and then vacuum dried at 40°C for 10 hours to prepare a laminate. The prepared laminate was cold-roll-pressed to flatten the surface, thereby preparing a cathode having a cathode coating layer / cathode current collector structure. The thickness of the cathode coating layer was approximately 15 μm. The surface area of ​​the cathode coating layer and the cathode current collector were the same.

[0225] (Preparation of solid electrolyte layer)

[0226] A mixture was prepared by adding 1.5 parts by weight of an acrylic binder to 98.5 parts by weight of a solid electrolyte (D50=3.0 (m, crystalline)) which is an argyrodite-type crystal. A slurry was prepared by stirring while adding octyl acetate to the prepared mixture. The prepared slurry was applied using a bar coater onto a 15 μm thick nonwoven fabric placed on a 75 μm thick PET substrate, and a laminate was prepared by drying in air at a temperature of 80 °C for 10 minutes. A solid electrolyte layer was prepared by vacuum drying the prepared laminate at 80 °C for 2 hours.

[0227] (Manufacturing of all-solid-state batteries)

[0228] The previously fabricated cathode layer, the solid electrolyte layer on the cathode layer, and the anode layer on the solid electrolyte layer were sequentially arranged. The prepared laminate was subjected to plate pressing at 85 °C under a pressure of 500 MPa for 30 minutes. This pressurization process sintered the solid electrolyte layer, thereby improving battery characteristics. The thickness of the sintered solid electrolyte layer was approximately 45 μm. The density of the Li6PS5Cl solid electrolyte, an argyrodite-type crystal contained in the sintered solid electrolyte layer, was 1.6 g / cc. The area of ​​the solid electrolyte layer was equal to the area of ​​the cathode layer.

[0229] An all-solid-state battery was manufactured by placing a pressurized laminate into a pouch and vacuum sealing it. Parts of the positive and negative current collectors were extended outside the sealed battery to serve as the positive and negative terminals.

[0230]

[0231] Example 2 - Preparation Example 1:Preparation Example 3:Solid Electrolyte = 80:5:15

[0232] An all-solid-state battery was manufactured in the same manner as in Example 1, except that the first positive active material of Manufacturing Example 1, the second positive active material of Manufacturing Example 3, and a positive electrode having a solid electrolyte content of 80:5:15 were manufactured.

[0233]

[0234] Example 3 - Preparation Example 1:Preparation Example 3:Solid Electrolyte = 80:10:10

[0235] An all-solid-state battery was manufactured in the same manner as in Example 1, except that the first positive active material of Manufacturing Example 1, the second positive active material of Manufacturing Example 3, and a positive electrode having a solid electrolyte content of 80:10:10 were manufactured.

[0236]

[0237] Example 4 - Preparation Example 2:Preparation Example 3:Solid Electrolyte = 80:2:18

[0238] An all-solid-state battery was manufactured in the same manner as in Example 1, except that the first positive active material of Preparation Example 2, the second positive active material of Preparation Example 3, and a positive electrode having a solid electrolyte content of 80:2:18 were manufactured.

[0239]

[0240] Example 5 - Preparation Example 1:Preparation Example 4:Solid Electrolyte = 80:5:15

[0241] An all-solid-state battery was manufactured in the same manner as in Example 1, except that the first positive active material of Preparation Example 1, the second positive active material of Preparation Example 4, and a positive electrode having a solid electrolyte content of 80:5:15 were manufactured.

[0242]

[0243] Comparative Example 1 - Preparation Example 1:Solid Electrolyte = 8:2

[0244] An all-solid-state battery was manufactured in the same manner as in Example 1, except that the content of the first positive active material and solid electrolyte of Manufacturing Example 1 was 8:2.

[0245]

[0246] Comparative Example 2 - Preparation Example 3: Solid Electrolyte = 8:2

[0247] An all-solid-state battery was manufactured in the same manner as in Example 1, except that the second positive electrode active material and solid electrolyte content of Manufacturing Example 3 were prepared in a ratio of 8:2.

[0248]

[0249] Table 1 below summarizes the compositions of the above-described examples and comparative examples.

[0250] (Content within the anode) 1st anode active material: 2nd anode active material: Solid electrolyte Example 1 80:2:18 Example 2 80:5:15 Example 3 80:10:10 Example 4 80:2:18 Example 5 80:5:15 Comparative Example 180:0:20 Comparative Example 20:80:20

[0251]

[0252] Evaluation Example 1 - Evaluation of First Anode Active Material and Second Anode Active Material

[0253] To confirm the characteristics of the first and second positive active materials, the ionic conductivity, electrical conductivity, and pellet density of each were measured. In this case, Preparation Example 1 was used as the first positive active material, and Preparation Example 3 was used as the second positive active material. Additionally, the electronic conductivity and ionic conductivity were measured using the DC polarization method, and the pellet density was measured using the thickness of a pellet prepared by applying uniaxial pressure of 440 MPa to 160 mg of the positive active material for 2 minutes. The results are summarized in Table 2 below.

[0254]

[0255] First positive active material, Second positive active material, Ion conductivity (S / cm) 6.42 x 10⁻⁶ -6 3.22x10 -5 Electron conductivity (S / cm) 1.12 x 10⁻⁶ -2 1.17x10 -2 Pellet Density (g / cc) 1.65 1.61

[0256] Looking at Table 2 above, it can be seen that the ionic conductivity and electron conductivity of the first and second positive active materials are excellent. In particular, it can be seen that the second positive active material has better ionic conductivity than the first positive active material.

[0257] Evaluation Example 2 - Measurement of capacity of first and second positive active materials

[0258] The capacity characteristics were verified when the first and second cathode active materials were used independently. In particular, for the second cathode active material, to verify the performance difference before and after compounding, the capacity characteristics were also verified when Li6PS5Cl and carbon black were simply mixed as a control group.

[0259] Specifically, a torque cell was manufactured in the following manner. At this time, the first positive active material (Preparation Example 1) and the second positive active material (Preparation Example 3) were used, respectively, as the positive active materials. For the control group, instead of the positive active material, Li6PS5Cl, which is a precursor of the second positive active material (Preparation Example 3), and carbon black were simply mixed and added.

[0260] (cathode)

[0261] A lower mold made of SUS material is placed inside a POM insulator having an inner diameter of 13pi, and after inserting a SUS foil (SUS foil, thickness 10um, size 13pi), a Li metal foil (thickness 20um, size 13pi) and an Indium metal foil (thickness 50um, size 13pi) are inserted.

[0262] (Solid electrolyte)

[0263] Then, 150 mg of solid electrolyte Li6PS5Cl (D50 = 3.0 μm, crystalline), which is an argyrodite-type crystal, was added, and uniaxial pressurization was performed at 38 MPa for 2 seconds.

[0264] (anode)

[0265] A cathode was prepared with a cathode active material to solid electrolyte content of 7:3. Li6PS5Cl (D50=1.0㎛, crystalline), an argyrodite-type crystal, was used as the solid electrolyte. Two types of powders were placed in a mortar and pestle and uniformly mixed to create a cathode mixture. 15 mg of this cathode mixture was placed on the solid electrolyte layer inside a torque cell to form a cathode layer, after which an upper mold made of SUS material was inserted and uniaxial pressure was applied at 300 MPa for 2 minutes. Subsequently, an all-solid-state battery was manufactured by tightening with a torque value of 4 Nm.

[0266] The all-solid-state battery prepared as described above was placed in a constant temperature bath at 45°C to measure the initial discharge capacity. Charging was performed in CC mode. The battery voltage was charged to 2.8 V at 0.05 C, and discharge was performed in CC mode at 0.05 C to 0.3 V. The discharge capacity of the first cycle was measured while performing the charge-discharge test once using the above method. The results are shown in Table 3.

[0267]

[0268] First positive active material (Preparation Example 1) Second positive active material (Preparation Example 3) Control group 1st discharge capacity (mAh / g) 880 800 81.8

[0269] Looking at Table 3 above, it was confirmed that the first and second cathode active materials can be used as lithium sources, and that the all-solid-state battery using them has excellent energy density. In particular, looking at the control group, it was confirmed that although the second cathode active material and Li6PS5Cl and carbon-based conductive material are used identically, when no composite is formed, they cannot be used as suitable lithium sources in the all-solid-state battery. In other words, it can be seen that the second cathode active material not only has high ionic conductivity and electronic conductivity as confirmed in Evaluation Example 1, but can also be used as a lithium source.

[0270]

[0271] Evaluation Example 3. Charge / Discharge Test

[0272] As described above, the first positive electrode active material has excellent capacitance characteristics but has somewhat low ionic conductivity, while the second positive electrode active material can contribute to the capacitance characteristics of the battery and has excellent ionic conductivity. Accordingly, the capacity of an all-solid-state battery prepared by mixing the first positive electrode active material and the second positive electrode active material was measured based on the electrode capacity. Specifically, the initial capacitance of Examples 1 to 5 was measured. As a control group, the initial capacitance of Comparative Examples 1 and 2, which use only one type of positive electrode active material, was measured.

[0273] At this time, the charge-discharge test was performed by placing the all-solid-state battery in a constant temperature bath at 45°C. Charging was carried out in CC mode. The battery voltage was charged to 2.8 V at 0.05C, and the discharge was carried out in CC mode at 0.05C to 1.0 V. The charge capacity and discharge capacity of the first cycle were measured while performing the charge-discharge test once using the above method. The results are shown in Table 4 below.

[0274]

[0275] Initial Charge Capacity (mAh / g) Initial Discharge Capacity (mAh / g) Initial Efficiency (%) Example 1 41 437 89 1.4 Example 2 44 240 39 1.2 Example 3 44 840 18 9.5 Example 4 40 736 99 0.7 Example 5 43 138 89 0.1 Comparative Example 1 39 934 58 6.4 Comparative Example 2 46 1370 80.3

[0276] Looking at Table 4 above, it can be seen that the capacity retention rate of Comparative Examples 1 and 2 is significantly reduced compared to Examples 1 to 5. In other words, it was confirmed that when the first positive active material and the second positive active material are mixed and used, both the capacity and the capacity retention rate are excellent. Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto and can be implemented with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that such modifications also fall within the scope of the present invention.

Claims

1. Positive current collector; and The anode active material layer on the anode current collector above; The above positive active material layer comprises a first positive active material, a second positive active material, and a solid electrolyte, and The first positive active material comprises a first composite containing a first lithium sulfide, a metal halide salt, and a first carbon-based conductive material, and The above second positive active material is Li 7-b PS 6-b Cl b A material formed by combining a compound represented by (0≤b≤2) and a second carbon-based conductive material, anode.

2. In Paragraph 1, The above second carbon-based conductive material is the above Li 7-b PS 6-b Cl b Coated on the surface of a compound represented by (0≤b≤2), anode.

3. In Paragraph 2, The average thickness of the above coating is 1 nm to 10 nm, anode.

4. In Paragraph 1, The above Li 7-b PS 6-b Cl b A compound represented by (0≤b≤2) and the second carbon-based conductive material are composited in a weight ratio of 3:1 to 7:1, anode.

5. In Paragraph 1, The average particle size (D50) of the first positive active material is 3 μm to 10 μm, anode.

6. In Paragraph 1, The average particle size (D50) of the second positive active material is 1 μm to 10 μm, anode.

7. In Paragraph 1, The above first lithium sulfide is Li2S n including at least one of (1 ≤ n ≤ 8, n is an integer), anode.

8. In Paragraph 1, The above metal halide salt comprises an alkali metal halide salt, a boron group metal halide salt, or a combination thereof. anode.

9. In Paragraph 8, The above alkali metal halide salt comprises at least one of LiF, LiCl, LiBr, LiI, or a combination thereof, and The above boron group metal halide salts are AlF3, AlCl3, AlBr3, AlI3, GaF3, GaCl3, GaBr3, GaI3, InF3, InCl3, lnBr3, lnI3, TlF3, TlCl3, TlBr3, and TlI 3, or including at least one combination thereof, anode.

10. In Paragraph 1, The first carbon-based conductive material comprises at least one of amorphous carbon, crystalline carbon, or a mixture thereof. anode.

11. In Paragraph 1, The first carbon-based conductive material comprises at least one of carbon black, acetylene black, furnace black, Kettjen black, activated carbon, carbon nanotubes (CNT), carbon nanofibers (CNF), carbon nanobelts, carbon nanorods, graphene, or a combination thereof. anode.

12. In Paragraph 1, The second carbon-based conductive material comprises at least one of amorphous carbon, crystalline carbon, or a mixture thereof. anode.

13. In Paragraph 1, The second carbon-based conductive material comprises at least one of carbon black, acetylene black, furnace black, Kettjen black, activated carbon, carbon nanotubes (CNT), carbon nanofibers (CNF), carbon nanobelts, carbon nanorods, graphene, or a combination thereof. anode.

14. In Paragraph 1, The above solid electrolyte is Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), Li 7-x PS 6-x I x A sulfide-based solid electrolyte of the argyrodite-type represented by (0≤x≤2), or at least one combination thereof, comprising anode.

15. In Paragraph 1, The content of the above solid electrolyte is 5% to 40% by weight of the total weight of the positive electrode active material layer, anode.

16. In Paragraph 1, The content of the second positive active material is 1% to 25% by weight of the total weight of the positive active material layer, anode.

17. In Paragraph 1, The weight ratio of the first lithium sulfide and the metal halide salt in the first positive electrode active material is 1:1 to 5:1, anode.

18. In Paragraph 1, The content of the first carbon-based conductive material is 5 to 25 weight percent of the total weight of the first positive active material, anode.

19. Anode according to paragraph 1; A cathode comprising a cathode current collector and a coating layer disposed on the cathode current collector; and A solid electrolyte layer disposed between the anode and the cathode, All-solid-state battery.

20. In Paragraph 19, The above cathode further includes a lithium metal layer disposed between the cathode current collector and the coating layer, and The above lithium metal layer comprises lithium or a lithium alloy, All-solid-state battery.

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