Positive electrode for all-solid-state battery, and all-solid-state battery comprising same

Abstract

The present invention relates to a positive electrode for a solid-state secondary battery and a solid-state secondary battery comprising same, wherein the positive electrode comprises: a positive electrode current collector; a carbon coating layer covering a surface of the positive electrode current collector; and a positive electrode active material layer on the carbon coating layer. The positive electrode active material layer comprises a composite and a solid electrolyte. The composite comprises a sulfur-based material, metal halide salts, and a carbon-based material, wherein the metal halide salts comprise a first metal halide salt including an alkali metal and a second metal halide salt including a boron group metal. One surface of the positive electrode current collector is in contact with the carbon coating layer.

Description

Anode for all-solid-state batteries and all-solid-state batteries including the same

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

[0002]

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

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

[0005] By employing a solid electrolyte instead of a liquid electrolyte, solid-state batteries can reduce the possibility of fire or explosion and provide enhanced safety.

[0006] When lithium sulfide is used as the positive electrode active material in solid-state batteries, a material with high electrical and ion conductivity is required during the manufacturing of the positive electrode because lithium sulfide is an insulator with almost no electrical or ion conductivity. Furthermore, since no solvent is used during the manufacturing of the positive electrode, electrolyte layer, and negative electrode containing lithium sulfide, the solid electrolyte layer, positive electrode, and negative electrode essentially contain no solvent; consequently, the electronic conductivity and lithium ion conductivity are low, making it impossible to secure sufficient capacity during charging and discharging.

[0007]

[0008] The problem that the present invention aims to solve is to provide a positive electrode for an all-solid-state battery that lowers interfacial electronic resistance by increasing the adhesion between the carbon coating layer covering the surface of the positive electrode current collector and the positive electrode active material layer and maximizing the contact area.

[0009] Another problem that the present invention aims to solve is to provide an all-solid-state battery comprising the anode.

[0010]

[0011] A positive electrode for an all-solid-state battery according to one embodiment may include a positive electrode current collector; a carbon coating layer covering the surface of the positive electrode current collector; and a positive electrode active material layer on the carbon coating layer. The positive electrode active material layer may include a composite and a solid electrolyte. The composite comprises a sulfur-based material, a metal halide salt, and a carbon-based material, and the metal halide salt may include a first metal halide salt comprising an alkali metal and a second metal halide salt comprising a boron group metal. One surface of the positive electrode current collector is in contact with the carbon coating layer, and the one surface of the positive electrode current collector may have an uneven structure.

[0012] A positive electrode for an all-solid-state battery according to another embodiment may include a positive electrode current collector; a carbon coating layer covering the surface of the positive electrode current collector; and a positive electrode active material layer on the carbon coating layer. The positive electrode active material layer may include a first composite and a solid electrolyte. The carbon coating layer may include a second composite. Each of the first and second composites may include a sulfur-based material, a metal halide salt, and a carbon-based material. The metal halide salt may include a first metal halide salt comprising an alkali metal and a second metal halide salt comprising a boron group metal.

[0013] A solid-state battery according to another embodiment may include the anode described above; a cathode; and a solid electrolyte layer disposed between the anode and the cathode.

[0014]

[0015] According to one aspect, an all-solid-state battery having improved lifespan characteristics can be provided by providing a positive electrode active material with improved electronic conductivity and ion conductivity.

[0016] According to another aspect, it is possible to provide an all-solid-state battery with improved cycle characteristics by strengthening the adhesion between the positive current collector and the positive active material layer, lowering the interfacial resistance between the positive current collector and the positive active material layer, and facilitating electron movement.

[0017] FIG. 1 is a cross-sectional view of an all-solid-state battery according to one embodiment.

[0018] FIG. 2 is an enlarged view illustrating an anode current collector having an uneven structure formed according to one embodiment.

[0019] Figure 3 is a schematic diagram illustrating the ion conduction pathway of lithium ions in the positive active material layer.

[0020] FIG. 4 is an enlarged schematic diagram illustrating the ion conduction path of lithium ions in a positive electrode active material layer according to one embodiment.

[0021] FIG. 5 is an enlarged view illustrating a positive electrode active material according to one embodiment.

[0022] FIGS. 6 to 9 are cross-sectional views of an all-solid-state battery according to one embodiment.

[0023] FIG. 10 is a perspective view of an all-solid-state battery according to one embodiment.

[0024] FIGS. 11a and FIGS. 11b are SEM images of the surface of an anode current collector fabricated according to one embodiment.

[0025] FIGS. 12a and FIGS. 12b are the analysis results of an anode cross-section fabricated according to one embodiment.

[0026]

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] In this specification, “metal” includes both metals and metalloids such as silicon and germanium in an elemental or ionic state.

[0032] In this specification, “alloy” means a mixture of two or more metals.

[0033] In this specification, “electrode active material” refers to an electrode material capable of undergoing lithiation and delithiation.

[0034] In this specification, “anode active material” refers to an anode material capable of undergoing lithiation and delithiation.

[0035] In this specification, “anode active material” refers to an anode material capable of undergoing lithiation and delithiation.

[0036] In this specification, “lithiation” and “to lithiate” refer to the process of adding lithium to an electrode active material.

[0037] In this specification, “delithiation” and “to delithiate” refer to the process of removing lithium from an electrode active material.

[0038] In this specification, “charge” and “to charge” refer to the process of providing electrochemical energy to a battery.

[0039] In this specification, “discharge” and “discharge” refer to the process of removing electrochemical energy from a battery.

[0040] In this specification, “anode” and “cathode” refer to electrodes where electrochemical reduction and lithiation occur during the discharge process.

[0041] In this specification, “negative electrode” and “anode” refer to electrodes where electrochemical oxidation and delithiation occur during the discharge process.

[0042] In this specification, “average surface roughness (R a )" refers to the degree of fine irregularities on the surface of the anode current collector. In this specification, the average surface roughness (R a Using a laser microscope (VK-X100k, Keyence), laser scanning was performed in Auto measure mode after focusing on the surface of the anode current collector at a magnification of ×150; the measurement standard was set according to JIS B0601:2001, and the measurement area was selected as "all areas" to measure R for the entire area. a was measured. R for each sample a The value is R at 10 points on the surface of the adhesion reinforcement layer while moving the sample's measurement position. a It was measured and expressed as the average value.

[0043] Although specific embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are not currently anticipated or cannot be anticipated may arise to the applicant or those skilled in the art. Accordingly, the appended claims, which may be filed and modified, are intended to include all such alternatives, modifications, variations, improvements, and substantial equivalents.

[0044]

[0045] FIG. 1 is a cross-sectional view of an all-solid-state battery according to one embodiment.

[0046] Referring to FIG. 1, an all-solid-state battery according to one embodiment may include a positive electrode layer (100), a negative electrode layer (200), and a solid electrolyte layer (300) disposed between the positive electrode layer (100) and the negative electrode layer (200).

[0047] Referring to FIG. 1, an anode layer (100) according to one embodiment may include an anode current collector (110), a carbon coating layer (130) covering the surface of the anode current collector (110), and an anode active material layer (120) disposed on the carbon coating layer (130).

[0048] The positive current collector (110) may provide a reference surface on which a carbon coating layer (130) is placed. The positive current collector (110) may include, for example, a plate or foil comprising aluminum (Al), nickel (Ni), stainless steel (SUS), indium (In), copper (Cu), magnesium (Mg), titanium (Ti), iron (Fe), cobalt (Co), zinc (Zn), germanium (Ge), lithium (Li), or an alloy thereof. The positive current collector (110) may use any current collector used in the art without limitation. According to one embodiment, the positive current collector (110) may use aluminum (Al) having a thickness of 3 μm to 500 μm, 5 μm to 100 μm, or 5 μm to 50 μm. If the thickness of the positive current collector (110) is less than the above range, the durability may be reduced, and if it exceeds the above range, the total weight of the battery may be excessively increased.

[0049] The above positive current collector (110) has an uneven surface formed on one side in contact with the carbon coating layer (130), thereby providing an average surface roughness (R a Can have ).

[0050] FIG. 2 is an enlarged view illustrating an anode current collector having an uneven structure formed according to one embodiment. In FIG. 2, the area corresponding to region A of FIG. 1 is shown in an enlarged view.

[0051] Referring to FIG. 2, the surface of the positive current collector (110) may have an uneven structure. For example, the surface of the positive current collector (110) may include protruding areas and recessed areas.

[0052] In order to maximize the improvement of the bonding strength between the positive current collector (110) and the carbon coating layer (130), the average surface roughness (R) of one side of the positive current collector (110) a The degree of irregularity formation can be adjusted so that ) is 0.01 μm or more. According to one embodiment, the average surface roughness (R) of one surface of the positive current collector (110) is a ) may be 0.01 μm to 5.0 μm. Average surface roughness (R a If the value is below the above range, it is difficult to obtain an improved bonding effect between one side of the positive current collector (110) and the carbon coating layer (130), and if the value exceeds the above range, a problem may occur in which the durability and stability of the positive current collector (110) are reduced.

[0053] The uneven structure may include a plurality of engraved regions formed at a certain depth (H) from the surface of the positive current collector (110) and having a certain width (W).

[0054] In this case, the width (W) of the above-mentioned uneven structure refers to the longest width among the widths of the indentations measured in the horizontal direction, and the depth (H) of the above-mentioned uneven structure refers to the vertical distance from the highest point to the lowest point of the indentation. When the width (W) and depth (H) of the above-mentioned uneven structure fall within the above range, the desired average surface roughness (R a ) values ​​can be represented. For example, the width (W) of the uneven structure formed on one surface of the positive current collector (110) may be 0.5 μm to 10 μm, and the depth (H) of the uneven structure may be 0.5 μm to 10 μm.

[0055] It is preferable that the depth (H) of the uneven structure be 30% or less of the total thickness of the positive current collector (110). If the depth (H) is greater than 30%, the mechanical strength of the positive current collector (110) becomes weak, and a problem may occur where the current collector breaks during the manufacture of a secondary battery. According to one embodiment, the depth (H) of the uneven structure may be 0.1% to 30% of the total thickness of the positive current collector (110).

[0056] Unevenness on the surface of the positive current collector (110) can be formed by methods such as etching. Etching, which is one of the methods for forming an uneven structure on the surface of the positive current collector (110), can be performed using a chemical etching method or an electrochemical etching method. In the chemical etching method used to etch the positive current collector (110), an acidic solution or an alkaline solution may be used. As acidic solutions used in the chemical etching method, hydrochloric acid, sulfuric acid, ferric chloride, etc. may be used. In addition, as alkaline solutions used in the chemical etching method, a solution containing sodium hydroxide may be used. However, the solutions used in the chemical etching method are not limited to those mentioned above, and various solutions capable of corroding the positive current collector (110) may be used.

[0057] In addition to the chemical etching method, an electrochemical etching method is used to form an etching area on the positive current collector (110). The electrochemical etching method supplies current to the positive current collector (110) to accelerate the etching process compared to the chemical etching method. That is, a direct current or alternating current is applied to the aluminum metal while the positive current collector (110) is immersed in an acidic or alkaline solution. At this time, the applied current is supplied at an appropriate value depending on the required etching area and depth. For example, in the electrochemical etching method, a current with a current density of several mA / cm² to several hundred mA / cm² is used. Also, when using an alternating current, a current having an appropriate alternating frequency range is supplied.

[0058] In addition to the method described above for forming irregularities on the surface of the positive current collector (110), various general methods for surface treatment of the positive current collector (110) may be used.

[0059] According to the present invention, when a carbon coating layer (130) is applied to one surface of an anode current collector (110) having irregularities, it can be seen that a path for current (ions) is effectively formed. According to one embodiment, when an anode current collector (110) having irregularities is applied, the bonding strength between the anode current collector (110) and the carbon coating layer (130) and the current path are increased, thereby improving high-temperature storage performance, energy density, and output.

[0060] In addition, the positive current collector (110) has an irregular curvature on its surface formed with an uneven structure, so that the surface area in contact with the carbon coating layer (130) described later is maximized, thereby allowing electron movement from the positive active material layer (120) to the positive current collector (110) to be smoother while lowering the interfacial resistance.

[0061]

[0062] Referring to FIGS. 1 and 2, a carbon coating layer (130) may be placed 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).

[0063] The carbon coating layer (130) may be placed directly on one side of the positive current collector (110), for example. No other layer may be placed between the positive current collector (110) and the carbon coating layer (130). By placing the carbon coating layer (130) directly on one side 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 carbon coating layer (130) between the positive current collector (110) and the positive active material layer (120), side reactions between the inorganic filler and / or solid electrolyte and the positive current collector (110) can be more effectively suppressed. Accordingly, the degradation of the all-solid-state battery (1000) during the charging and discharging process can be suppressed, and the cycle characteristics of the all-solid-state battery (1000) can be further improved.

[0064] The thickness (d) of the carbon coating layer (130) 130 ) is, for example, 0.01 to 20%, 0.1 to 20%, 0.5 to 20%, 1 to 20%, 1 to 15%, 1 to 10%, 2 to 8%, or 3 to 7% of the thickness of the positive current collector (110). The thickness of the carbon coating layer (130) is, for example, 20 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 1.0 µm. By having the carbon coating layer (130) have a thickness within this range, the bonding strength between the positive current collector (110) and the positive active material layer (120) is further improved, and the increase in interfacial resistance is suppressed. The thickness (d) of the carbon coating layer (130) 130 ) can be measured, for example, from a scanning electron microscope (SEM) image of a cross-section of the intermediate layer.

[0065] The carbon coating layer (130) may include, for example, a conductive carbon material (CAM). The carbon material (CAM) included in the carbon coating layer (130) may be selected from the conductive materials used in the positive active material layer (120). The carbon coating layer (130) may include the same conductive material as the conductive material used in the positive active material layer (120). By including the carbon material (CAM) in the carbon coating layer (130), the carbon coating layer (130) may be, for example, a conductive layer.

[0066] According to one embodiment, the carbon material (CAM) may include carbon nanostructures. The size of the carbon nanostructures may be, for example, 10 nm to 800 nm, 50 nm to 500 nm, or 10 nm to 300 nm. For example, the carbon nanostructures may include carbon nanofibers (CNF), carbon nanotubes (CNT), graphene, and carbon black, or a combination thereof.

[0067] The carbon coating layer (130) includes a carbon material (CAM) having a nanoparticle size, thereby allowing a large amount of carbon material to be uniformly distributed in the recessed portion of the unevenness of the anode current collector (110) described above. The content of the carbon material (CAM) included in the carbon coating layer (130) may be, for example, 10% to 60% by weight, or 30% to 50% by weight of the total weight of the anode carbon coating layer (130).

[0068] The carbon coating layer (130) may further include an adhesive polymer (ADP). By additionally including the adhesive polymer (ADP) in the carbon coating layer (130), the bonding strength between the positive current collector (110) and the positive active material layer (120) can be further improved.

[0069] The above adhesive polymer (ADP) may include polydopamine, poly(3,4-ethylenedioxythiophene; PEDOT), polyanilines (PANI), polyacrylate, cation-substituted polycarboxylic acid, cation-substituted polycarboxylic acid copolymer, polynorepinephrine, poly(meth)acrylamide, polyvinyl alcohol, polyhydroxyethyl(meth)acrylate, polymethyl(meth)acrylate-(meth)acrylic acid copolymer, polymethyl(meth)acrylate, poly(meth)acrylic acid), styrene-(meth)acrylic acid copolymer, or a combination thereof.

[0070] The above-mentioned cation-substituted polycarboxylic acid and its copolymer are lithium ions (Li + ), sodium ions (Na + ), potassium ions (K + and ammonium ions (NH₃) 4+ It has one cation selected from among ). Polycarboxylic acid refers to a polymer formed by the polymerization of various types of monomers containing one or more monomers having one or more carboxyl groups (-COOH), and has a weight-average molecular weight of 1,000 to 1,000,000. Examples of such polycarboxylic acids include polyacrylic acid, polymethacrylic acid, and polymaleic acid. Cation-substituted polycarboxylic acid is a substance in which the hydrogen of such polycarboxylic acid is substituted with a cation, and includes, for example, one or more selected from lithium polyacrylate (LiPAA) and lithium polymethacrylate.

[0071] Cation-substituted polycarboxylic acid copolymers are copolymers containing monomer repeating units corresponding to cation-substituted polycarboxylic acids, and examples of such copolymers include poly(acrylic acid-co-maleic acid) lithium salt, poly(methylvinyl ether-alt-maleic acid) lithium salt, or poly(butadiene-co-maleic acid) lithium salt.

[0072] The content of the adhesive polymer (ADP) included in the carbon coating layer (130) may be, for example, 30% to 80% by weight, 30% to 50% by weight, or 20% to 40% by weight of the total weight of the anode carbon coating layer (130). If the adhesive polymer (ADP) in the carbon coating layer (130) is included in an amount less than the above range, the adhesive effect is negligible, and if it is included in an amount exceeding the above range, the amount of polymer is excessively large, which may cause a problem of increased resistance of the carbon coating layer (130).

[0073] A carbon coating layer (130) can be placed on the positive current collector (110) in a dry or wet manner, for example. An intermediate layer (130) can be placed on the positive current collector (110) in a dry manner by deposition, for example, CVD, PVD, etc. A carbon coating layer (130) can be placed on the positive current collector (110) in a wet manner, for example, by spin coating, dip coating, etc. A carbon coating layer (130) can be placed on the positive current collector (110) by, for example, depositing carbon nanoparticles onto a substrate by deposition. A carbon coating layer (130) can be placed on the positive current collector (110) by, for example, coating a composition comprising a carbon material (CAM), an adhesive polymer (ADP), and a solvent onto the surface of the electrode current collector and drying it.

[0074] The carbon coating layer (130) not only prevents adverse reactions between the sulfide-based solid electrolyte and the conductive material present in the positive active material layer (120), but also has high adhesion, thereby improving the adhesion between the positive current collector (110) and the positive active material layer (120) and lowering the interfacial electrical resistance.

[0075]

[0076] Referring to FIGS. 3 and 4, a positive active material layer (120) according to one embodiment may include a positive active material (10, 11), a solid electrolyte (20, 21), and a conductive material (30). In another embodiment, the conductive material (30) may be omitted.

[0077] FIG. 3 is a schematic diagram illustrating the ion conduction path (R1) and the blocked ion conduction path (R2) of lithium ions in the positive electrode, and FIG. 4 is an enlarged schematic diagram illustrating the ion conduction path (R1) of lithium ions in the positive electrode active material layer (120) according to one embodiment. In FIG. 3 and FIG. 4, the area corresponding to region B of FIG. 1 is illustrated in an enlarged manner.

[0078] The cathode active material (10, 11) may contain elemental sulfur (S). Sulfur is attracting attention as a next-generation cathode material because it has a high theoretical capacity (1,672 mAh / g), is abundant on Earth, and is relatively inexpensive. In one embodiment, the elemental sulfur (S) is S8 and Li2S n It may exist in the form of a sulfur-based material containing at least one of (1 ≤ n ≤ 8, where n is an integer). Such sulfur-based materials have relatively low ionic conductivity. Therefore, the positive active material layer (120) may include a solid electrolyte (20) to form an ionic conduction path (R1).

[0079] Referring to FIG. 3, the solid electrolyte (20) can form an ion conduction path (R1) to move lithium ions. However, if there is not enough solid electrolyte (20) in the positive active material layer (120), a blocked ion conduction path (R2) may be formed. Additionally, a solid electrolyte (21) isolated by the positive active material (11) may occur. The blocked ion conduction path (R2) and the isolated solid electrolyte (21) can reduce the ion conductivity of the positive active material layer (120) and unnecessarily waste the positive active material (11) and solid electrolyte (20, 21), thereby lowering the energy density of the battery.

[0080] The positive active material (10) according to one embodiment may have relatively excellent ionic conductivity. The ionic conductivity of the positive active material (10) according to one embodiment is 3 x 10 at 25 ℃. -6 It can be greater than S / cm. For example, the ionic conductivity of the positive active material (10) is 3.5 x 10 -6 It may be greater than S / cm, and 4 x 10 -6 It may be greater than S / cm, and 5 x 10 -6 It may be greater than S / cm, and 6 x 10 -6 It may be greater than S / cm, and 6.75 x 10 -6 It may be greater than S / cm. The ionic conductivity of the positive active material (10) according to one embodiment is 1 x 10 -4 It can be less than S / cm. Ionic conductivity can be measured using the DC polarization method. Alternatively, ionic conductivity can be measured using the complex impedance method.

[0081] Referring to FIG. 4, the positive active material (10) according to one embodiment may have ion conductivity. The positive active material layer (120) containing the positive active material (10) according to one embodiment may form an ion conduction path (R1) passing through solid electrolyte (20) - positive active material (10) - solid electrolyte (20). The positive active material layer (120) containing the positive active material (10) according to one embodiment may form an ion conduction path (R1) passing through an isolated solid electrolyte (21). The positive active material layer (120) containing the positive active material (10) according to one embodiment may reduce blocked ion conduction paths (R2), thereby improving ion conductivity and improving energy density.

[0082] 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.

[0083] A solid electrolyte (20) according to one embodiment may comprise 10 to 60 parts by weight per 100 parts by weight of the positive active material layer (120). For example, a solid electrolyte (20) according to one embodiment may comprise 15 to 50 parts by weight, 20 to 40 parts by weight, or 25 to 35 parts by weight per 100 parts by weight of the positive active material layer (120). When satisfying the above ranges, a secondary battery according to one embodiment may have excellent capacity characteristics.

[0084] FIG. 5 is an enlarged view illustrating a positive electrode active material (10) according to an exemplary embodiment. In FIG. 5, the region corresponding to region C of FIG. 4 is illustrated in an enlarged view. Hereinafter, the positive electrode active material (10) according to the embodiment will be described in detail with reference to FIG. 5.

[0085] Referring to FIG. 5, the positive active material (10) according to the embodiment may include a composite of a sulfur-based material (1), a metal halide salt (2, 3), and a carbon-based material (4).

[0086] The positive active material (10) may have a particle form. The particle size of the positive active material (10), that is, the size of the composite particle, may be, for example, 50 μm or less, 30 μm or less, or 10 μm or less. The size of the composite particle may be, for example, 0.1 μm to 50 μm or 1 μm to 10 μm. As the composite particle has a size within this range, the volume change during charging and discharging is suppressed, thereby suppressing the degradation of the positive active material (10) containing the composite during charging and discharging. If the size of the composite particle increases excessively, the volume change of the composite during charging and discharging increases, thereby promoting the degradation of the positive active material (10) containing the composite. Consequently, the cycle characteristics of the secondary battery containing such a positive active material (10) may be degraded.

[0087] Accordingly, the cycle characteristics, for example, lifespan characteristics of a secondary battery containing a positive electrode active material (10) can be improved. The size of the composite particles may be, for example, the particle diameter of the composite. The particle diameter of the composite can be measured using, for example, a laser diffraction detector, a scanning electron microscope, etc. The particle diameter of the composite is, for example, the arithmetic mean value of the particle diameters of a plurality of particles measured using software in a scanning electron microscope image.

[0088] The positive active material (10) may include a sulfur-based material (1). The sulfur-based material (1) is S8 and Li2S nIt may include at least one of (1 ≤ n ≤ 8, n is an integer).

[0089] A sulfur-based material (1) undergoes a continuous oxidation / reduction reaction of sulfur and / or lithium sulfide. For example, the reaction process of lithium polysulfide and lithium sulfide by the continuous reduction reaction of sulfur in the sulfur-based material (1) can be expressed as S8→Li2S8→Li2S6→Li2S4→Li2S2→Li2S, etc. In this process, lithium ions move between the anode and cathode, and at the same time, electrons move through an external circuit to generate an electric current. According to one embodiment, the sulfur-based material (1) may include Li2S.

[0090] The content of the sulfur-based material (1) according to one embodiment may be 20 to 80 weight% with respect to the total weight of the composite. For example, the content of the sulfur-based material (1) according to one embodiment may be 30 to 70 weight% or 35 to 60 weight% with respect to the total weight of the composite.

[0091] The positive active material (10) may include metal halide salts (2, 3). The metal halide salts (2, 3) may include a first metal halide salt (2) containing an alkali metal and a second metal halide salt (3) containing a boron group metal. According to one embodiment, the metal halide salts (2, 3) may form a composite with the sulfur-based material (1) described above.

[0092] According to one embodiment, the content of the metal halide salt (2, 3) may be 10 to 60 weight% with respect to the total weight of the composite. For example, according to one embodiment, the content of the metal halide salt (2, 3) may be 20 to 50 weight% or 25 to 45 weight% with respect to the total weight of the composite.

[0093] The first metal halide salt (2) may be a binary compound composed of, for example, an alkali metal and one element selected from Group 17 of the periodic table. The first metal halide salt (2) may be, for example, a lithium salt. The first metal halide salt (2) may include, for example, LiI, LiF, LiCl, LiBr, or a combination thereof. This first metal halide salt (2) can form a composite with a sulfur-based material (1) to improve the ionic conductivity of a positive electrode active material (10) containing the sulfur-based material (1). This first metal halide salt (2) can more easily form a solid solution with the sulfur-based material (1) within the composite.

[0094] According to one embodiment, the content of the first metal halide salt (2) may be 2.5 to 15 weight% with respect to the total weight of the composite. For example, according to one embodiment, the content of the first metal halide salt (2) may be 5 to 12.5 weight% or 7 to 10 weight% with respect to the total weight of the composite.

[0095] In one embodiment, the positive active material (10) may have a weight ratio of the sulfur-based material (1) to the first metal halide salt (2) of 30:1 to 1:1. For example, in one embodiment, the positive active material (10) may have a weight ratio of the sulfur-based material (1) to the first metal halide salt (2) of 20:1 to 2:1 or 10:1 to 3:1.

[0096] The second metal halide salt (3) may be a binary compound composed of, for example, a boron group metal and one element selected from Group 17 of the periodic table. The second metal halide salt (3) may include, for example, AlI3, AlF3, AlCl3, AlBr3, GaF3, GaCl3, GaBr3, GaI3, InF3, InCl3, lnBr3, lnI3, TiF3, TiCl3, TiBr3, TiI3, or a combination thereof. This second metal halide salt (3) can form a composite with the sulfur-based material (1) and the first metal halide salt (2) to maintain the overall shape of the positive active material (10) containing the sulfur-based material (1) and the first metal halide salt (2) and to lower the interfacial resistance. This second metal halide salt (3) can more easily form a solid solution with the sulfur-based material (1) and the first metal halide salt (2) within the composite, for example. The positive active material (10) containing this second metal halide salt (3) can improve the capacity characteristics of the battery by suppressing the leaching of lithium polysulfide (Li2Sx).

[0097] According to one embodiment, the content of the second metal halide salt (3) may be 7.5 to 45 weight% with respect to the total weight of the composite. For example, according to one embodiment, the content of the second metal halide salt (3) may be 15 to 37.5 weight% or 20 to 31 weight% with respect to the total weight of the composite.

[0098] In one embodiment, the positive active material (10) may have a weight ratio of the sulfur-based material (1) to the second metal halide salt (3) of 10:1 to 1:1. For example, in one embodiment, the positive active material (10) may have a weight ratio of the sulfur-based material (1) to the second metal halide salt (3) of 5:1 to 1:1 or 5:1 to 2:1.

[0099] The positive electrode active material (10) may include different types of metal halide salts (2, 3). The different types of metal halide salts (2, 3) may include the first metal halide salt (2) and the second metal halide salt (3) described above. The positive electrode active material (10) according to the embodiment includes different types of metal halide salts (2, 3) to improve ion conductivity while maintaining the overall shape and reducing interfacial resistance, and can improve the capacity characteristics of the battery by suppressing the leaching of lithium polysulfide (Li2Sx).

[0100] In one embodiment, the positive active material (10) may have a weight ratio of the first metal halide salt (2) and the second metal halide salt (3) of 5:1 to 1:20. For example, the weight ratio of the first metal halide salt (2) and the second metal halide salt (3) may be 3:1 to 1:9, 1:1 to 1:9, or 1:3 to 1:9. The positive active material (10) satisfying the above range may include different types of metal halide salts (2, 3) in appropriate proportions to maximize the effect of improving the capacity characteristics described above.

[0101] A composite according to one embodiment may include a solid solution of the aforementioned sulfur-based material (1) and metal halide salts (2, 3).

[0102] According to one embodiment, the ionic conductivity of the composite may be increased by including a solid solution of a sulfur-based material (1) and a first metal halide salt (2). For example, since the solid solution of the sulfur-based material (1) and the first metal halide salt (2) contains alkali metal ions disposed within the crystallites of the sulfur-based material (1), the ionic conductivity of the solid solution of the sulfur-based material (1) and the first metal halide salt (2) may be improved compared to the ionic conductivity of the sulfur-based material (1). Consequently, the ionic conductivity of the composite may be improved and the internal resistance of the composite may be reduced. By including such a composite in the positive active material (10), the cycle characteristics of the secondary battery containing the positive active material (10) may be improved. For example, the high-rate characteristics of the secondary battery containing such a positive active material (10) may be improved.

[0103] According to one embodiment, the composite can maintain its overall shape and lower interfacial resistance by including a solid solution of a sulfur-based material (1) and a second metal halide salt (3). For example, since the solid solution of the sulfur-based material (1) and the second metal halide salt (3) maintains the overall shape of the composite, the sulfur-based material (1) undergoes oxidation / reduction to produce S8 and Li2S n Even if the shape is deformed between (1 ≤ n ≤ 8, where n is an integer), the shape deformation of the composite and the positive active material (10) can be minimized. By including such a composite in the positive active material (10), the shape deformation during the charging / discharging process can be minimized, thereby improving cycle characteristics.

[0104] A solid solution according to one embodiment is (1-xy)Li2S n It may include -xAX-yBX3 or (1-xy)S8-xAX-yBX3. The x and the y are 0.01 < x < 0.3 and 0.01 < y < 0.3, and the n is an integer such that 1 ≤ n ≤ 8, the A is an alkali metal, the B is a boron group metal, and the X is a halogen element.

[0105] The positive active material (10) may include a carbon-based material (4). The carbon-based material (4) may form a composite with the aforementioned sulfur-based material (1) and metal halide salts (2, 3). The composite of the carbon-based material (4), the sulfur-based material (1), and the metal halide salts (2, 3) is distinguished from a simple mixture of the carbon-based material (4), the sulfur-based material (1), and the metal halide salts (2, 3). A simple mixture of the carbon-based material (4), the sulfur-based material (1), and the metal halide salts (2, 3) fails to maintain a dense interface between the carbon-based material (4), the sulfur-based material (1), and the metal halide salts (2, 3), resulting in high interfacial resistance and consequently degrading the lifespan characteristics of the secondary battery.

[0106] The carbon-based material (4) may be any material containing carbon atoms, for example, used as a conductive material in the relevant technical field. The carbon-based material (4) may include, for example, crystalline carbon, amorphous carbon, or a combination thereof. The carbon-based material (4) may include, for example, a calcined product of a carbon precursor. The carbon-based material (4) may be, for example, a carbon nanostructure. The carbon nanostructure may include, for example, a one-dimensional carbon nanostructure, a two-dimensional carbon nanostructure, a three-dimensional carbon nanostructure, or a combination thereof. The carbon nanostructure may include, for example, carbon nanotubes (CNT), carbon nanofibers (CNF), carbon nanobelts, carbon nanorods, graphene, or a combination thereof. The carbon-based material (4) may be, for example, a porous carbon-based material or a non-porous carbon-based material. The porous carbon-based material may include, for example, periodic and regular two-dimensional or three-dimensional pores. The porous carbon-based material may include, for example, carbon black such as Ketjen black, acetylene black, Denka black, thermal black, and channel black, graphite, activated carbon, or a combination thereof. The form of the carbon-based material (4) may be, for example, particle form, sheet form, flake form, etc., but is not limited to these, and any form used as a carbon-based material (4) in the relevant technical field is possible.

[0107] The carbon-based material (4) according to one embodiment may include, for example, a fibrous carbon-based material (4). By including the fibrous carbon-based material (4) in the composite, the electron conductivity of the composite may be further improved. By including the fibrous carbon-based material (4) in the composite, electron conduction from the surface to the interior of the composite may be performed more easily. The internal resistance of the positive active material (10) including such a composite is reduced, and the cycle characteristics of the secondary battery including the positive active material (10) may be further improved.

[0108] The aspect ratio of the fibrous carbon-based material may be, for example, 2 or more, 3 or more, 4 or more, 5 or more, 10 or more, or 20 or more. The aspect ratio of the fibrous carbon-based material may be, for example, 2 to 30, 3 to 30, 4 to 30, 5 to 30, 10 to 30, or 20 to 30. The aspect ratio of the fibrous carbon-based material may be, for example, 2 to 30, 2 to 20, 2 to 10, 2 to 8, 2 to 5, or 2 to 4. By having the fibrous carbon-based material have an aspect ratio within this range, the overall electronic conductivity of the composite is improved, and the imbalance of local electronic conductivity within the composite can be further alleviated.

[0109] The diameter of the fibrous carbon-based material may be, for example, 0.01 μm to 10 μm, 0.05 μm to 10 μm, or 0.1 μm to 5 μm. The length of the fibrous carbon-based material may be, for example, 1 μm to 50 μm or 1 μm to 20 μm. The diameter and length of the fibrous carbon-based material may be measured from scanning electron microscope (SEM) or transmission electron microscope (TEM) images. Alternatively, the diameter and / or length of the fibrous carbon-based material may be measured by laser diffraction.

[0110] According to one embodiment, the content of the carbon-based material (4) may be 1 to 30 weight% with respect to the total weight of the composite. For example, according to one embodiment, the content of the carbon-based material (4) may be 1 to 20 weight%, 5 to 20 weight%, or 10 to 20 weight% with respect to the total weight of the composite. If the content of the carbon-based material (4) increases excessively, the energy density of the battery may decrease. If the content of the carbon-based material (4) decreases excessively, the electronic conductivity of the composite decreases, and the internal resistance of the positive active material (10) may increase. A battery comprising a positive active material (10) that satisfies the content range of the carbon-based material (4) may have improved cycle characteristics.

[0111] The positive active material (10) according to one embodiment may have relatively excellent electron conductivity by including the carbon-based material (4) described above. The electron conductivity of the positive active material (10) according to one embodiment at 25°C is 5 x 10 -3 It can be greater than S / cm. For example, the electron conductivity of the positive active material (10) is 6.5 x 10 -3 It may be greater than S / cm, and 7 x 10 -3 It may be greater than S / cm, and 8 x 10 -3 It may be greater than S / cm. The electron conductivity of the positive active material (10) according to one embodiment is 1 x 10 -1 It may be less than S / cm.

[0112] The pellet density of the positive active material (10) according to one embodiment may be 1.5 g / cc or higher. For example, the pellet density of the positive active material (10) according to one embodiment may be 1.6 g / cc or higher, 1.62 g / cc or higher, 1.64 g / cc or higher, or 1.7 g / cc or higher. A secondary battery containing a positive active material (10) satisfying the above range may have improved energy density. The pellet density of the positive active material (10) according to one embodiment may be 5 g / cc or lower, 4 g / cc or lower, or 3 g / cc or lower.

[0113] A positive active material layer (120) according to one embodiment may include the positive active material (10) and solid electrolyte (20) described above.

[0114] The solid electrolyte (20) can provide an ion transport pathway within the positive active material layer (120). The positive active material layer (120) according to an embodiment may have a further reduced internal resistance by including the positive active material (10) and the solid electrolyte (20) described above.

[0115] Referring to FIGS. 3 to 5, the solid electrolyte (20) may have a particle shape. The solid electrolyte (20) may be dispersed among the positive electrode active materials (10). The solid electrolyte (10) 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).

[0116] Sulfide-based solid electrolytes are, for example, Li 7-a M a-1 PS 6-c X cIt may be an argyrodite-type compound represented by (1≤a≤2, 0≤c≤2). The above X is F, Br, Cl, or a combination thereof, and the above M is candium (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), It may include bismuth (Bi) or a combination thereof.

[0117] In particular, the sulfide-based solid electrolyte may be an azirodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I. The density of the azirodite-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 azirodite-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.

[0118] 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). According to one embodiment, the solid electrolyte (20) may comprise 10 to 60 parts by weight per 100 parts by weight of the positive active material layer (120). As described above, the positive active material (10) according to one embodiment includes a composite having electronic conductivity and ion conductivity as itself, so that even if a relatively large part by weight is included in the positive active material layer (120), the cycle characteristics of the battery can be maintained above a certain level. According to one embodiment, the positive active material (10) may comprise 60 to 80 parts by weight per 100 parts by weight of the positive active material layer (120), and the solid electrolyte (20) may comprise 20 to 40 parts by weight per 100 parts by weight of the positive active material layer (120). When the positive active material layer (120) has a positive active material (10) and solid electrolyte (20) content within the above range, a secondary battery with excellent capacity characteristics can be provided.

[0119] The content of the sulfur-based material (1) in the positive active material layer (120) may be 10 to 60 weight% with respect to the total weight of the positive active material layer (120). For example, the content of the sulfur-based material (1) in the positive active material layer (120) may be 20 to 50 weight% or 25 to 45 weight% with respect to the total weight of the positive active material layer (120).

[0120] The content of the metal halide salt (2, 3) in the positive active material layer (120) may be 10 to 40 weight% with respect to the total weight of the positive active material layer (120). For example, the content of the metal halide salt (2, 3) in the positive active material layer (120) may be 15 to 30 weight% with respect to the total weight of the positive active material layer (120).

[0121] The content of the first metal halide salt (2) in the positive active material layer (120) may be 2.5 to 10 weight% with respect to the total weight of the positive active material layer (120). For example, the content of the first metal halide salt (2) in the positive active material layer (120) may be 3.3 to 6.6 weight% with respect to the total weight of the positive active material layer (120).

[0122] The content of the second metal halide salt (3) in the positive active material layer (120) may be 7.5 to 30 weight% with respect to the total weight of the positive active material layer (120). For example, the content of the second metal halide salt (3) in the positive active material layer (120) may be 10 to 20 weight% with respect to the total weight of the positive active material layer (120).

[0123] The content of elemental sulfur (S) contained in the positive active material layer (120) according to one embodiment may be 10 to 65 weight% with respect to the total weight of the positive active material layer.

[0124] Referring to FIGS. 3 and 4, the positive active material layer (120) may further include a conductive material (30). The conductive material (30) may have conductivity without causing chemical changes, thereby increasing the electrical conductivity of the positive active material (10) and the solid electrolyte (20). The conductive material may include a carbon-based material. The conductive material may include, for example, one or more selected from graphite, carbon black, acetylene black, carbon nanofibers, and carbon nanotubes.

[0125] The positive active material layer (120) may further include a binder. The binder may bind the positive active material (10), solid electrolyte (20), and conductive material (30), etc., within the positive active material layer (120). The binder may include a material for improving the bonding strength between the positive active material layer (120) and the positive current collector (110). The binder may include, for example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, or a combination thereof. The content of the binder included in the positive active material layer (120) may be, for example, 0.5% to 5% by weight or 0.5% to 2% by weight of the total weight of the positive active material layer (120). In one embodiment, the binder may be omitted.

[0126] The positive active material layer (120) may further include additives such as fillers, coating agents, dispersants, and ion conductivity aids in addition to the positive active material (10), solid electrolyte (20), conductive material (30), and binder described above. Known materials generally used in electrodes of all-solid-state batteries may be used as fillers, coating agents, dispersants, and ion conductivity aids that may be included in the positive active material layer (120).

[0127]

[0128] Referring to FIGS. 1 and 2, in another embodiment, the anode layer (100) may further include an anode active material (10) in the carbon coating layer (130). For example, the anode layer (100) may include an anode active material (10) in each of the anode active material layer (120) and the carbon coating layer (130). The anode active material (10) may include a composite of a sulfur-based material (1), a metal halide salt (2, 3), and a carbon-based material (4). The metal halide salt (2, 3) may include a first metal halide salt containing an alkali metal and a second metal halide salt containing a boron group metal.

[0129] According to another embodiment, the anode layer (100) may include an anode current collector (110), a carbon coating layer (130) covering the surface of the anode current collector (110), and an anode active material layer (120) disposed on the carbon coating layer (130). The anode active material layer (120) may include a first anode active material (10) and a solid electrolyte (20). The first anode active material (10) may include a first composite of a sulfur-based material (1), a metal halide salt (2, 3), and a carbon-based material (4).

[0130] The above positive current collector (110) and positive active material layer (120) have been described above, so a detailed description thereof is omitted below.

[0131] The carbon coating layer (130) may include a second positive active material (10). The second positive active material (10) may include a second composite of a sulfur-based material (1), a metal halide salt (2, 3), and a carbon-based material (4).

[0132] The second positive active material (10) included in the carbon coating layer (130) may be the same as the first positive active material (10) included in the positive active material layer (120) described above.

[0133] The content of the second composite included in the carbon coating layer (130) may be, for example, 0.1% to 20% by weight of the total weight of the carbon coating layer (130), or 5% to 10% by weight.

[0134] Although not shown in the drawing, the second composite included in the carbon coating layer (130) may be located in the recessed portion of the protrusions and indentations of the positive current collector (110) described above by a pressurization process during the manufacture of the all-solid-state battery (1000).

[0135] According to another embodiment, the carbon coating layer (130) may provide an all-solid-state battery having improved lifespan characteristics by including a small amount of a second composite with improved electronic conductivity and ion conductivity.

[0136] Since the first and second complexes above are identical to the complex composition included in the positive active material layer (120) according to the previous embodiment, a detailed description thereof is omitted below.

[0137] According to another embodiment, each of the first and second composites may have a content of the sulfur-based material of 20% to 80% by weight with respect to the total weight of the composite, a content of the metal halide salt of 10% to 60% by weight with respect to the total weight of the composite, and a content of the carbon-based material of 1% to 30% by weight with respect to the total weight of the composite.

[0138]

[0139] Referring again to FIG. 1, an all-solid-state battery (1000) according to one embodiment may include a solid electrolyte layer (300) disposed between a positive electrode layer (100) and a negative electrode layer (200). The solid electrolyte layer (300) may include a sulfide-based solid electrolyte with excellent lithium ion conductivity characteristics. The solid electrolyte in the solid electrolyte layer (300) may be the same as or different from any one of the materials included in the solid electrolyte (20) in the positive electrode active material layer (120) described above.

[0140] Referring to FIG. 1, an all-solid-state battery (1000) according to one embodiment may include a negative electrode layer (200). The negative electrode layer (200) may include a negative electrode current collector (210) and a negative electrode coating layer (220) disposed on the negative electrode current collector (210).

[0141] The negative current collector (210) may provide a reference surface on which the negative coating layer (220) is disposed. The negative current collector (210) may include, for example, a material that does not react with lithium, that is, does not form any alloys or compounds with lithium. The material constituting the negative current collector (210) may include at least one metal selected from the group consisting of, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The thickness of the negative current collector may be 1 to 20 μm, for example 5 to 15 μm, for example 7 to 10 μm.

[0142] The negative current collector (210) may be composed of one of the metals described above, or may include an alloy of two or more metals or a coating material. The negative current collector (210) is, for example, in the form of a plate or foil. In another embodiment, the negative current collector (210) may be omitted.

[0143] The negative electrode coating layer (220) can be configured to allow lithium metal to grow between the negative electrode current collector (210) and the all-solid-state battery (1000) during charging. The negative electrode coating layer (220) can serve as a protective layer for the lithium metal and simultaneously suppress the precipitation and growth of lithium dendrites.

[0144] The cathode coating layer (220) may include a metal-carbon composite. The metal-carbon composite may be a composite of metal particles and a carbon-based material. The metal-carbon composite may have, for example, a particle form. The average particle size of the metal-carbon composite having a particle form is, for example, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, or 900 nm or less. The average particle size of the metal-carbon composite having a particle form is, for example, 10 nm to 4 μm or less, 10 nm to 3 μm or less, 10 nm to 2 μm or less, 10 nm to 1 μm or less, or 10 nm to 900 nm or less. By having the average particle size of the metal-carbon composite within this range, reversible absorption and / or desorption of lithium during charging and discharging may be more facilitated. The average particle size of the metal-carbon composite is, for example, the median diameter (D50) measured using a laser particle size distribution meter.

[0145] The metal particles within the metal-carbon composite may comprise at least one metal or metalloid selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The carbonaceous material within the metal-carbon composite may comprise at least one selected from the group consisting of carbon black, acetylene black, furnace black, Kettjen black, and graphene. The carbonaceous material within the metal-carbon composite may be amorphous carbon. Amorphous carbon may be carbon that does not have crystallinity or has very low crystallinity.

[0146] The mixing ratio of metal particles and carbon-based material included in the cathode coating layer (220) may be, for example, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1 by weight. The content of metal particles included in the cathode coating layer (220) may be 8 to 60 weight%, 10 to 50 weight%, 15 to 40 weight%, or 20 to 30 weight% based on the total weight of the metal-carbon composite. By having the metal particles in this range, the cycle characteristics of the all-solid-state battery (1000) may be improved.

[0147] The cathode coating layer (220) may further include other additives in addition to the metal-carbon composite. The cathode 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.

[0148] The negative electrode coating layer (220) may have a smaller thickness compared to the positive electrode active material layer (120). The thickness of the negative electrode 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 electrode active material layer (120). The thickness of the negative electrode 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 negative electrode coating layer (220) is excessively thin, lithium dendrites formed between the negative electrode coating layer (220) and the negative electrode current collector (210) may cause the negative electrode coating layer (220) to collapse, thereby degrading the cycle characteristics of the all-solid-state battery (1000). If the thickness of the negative electrode coating layer (220) increases excessively, the energy density of the all-solid-state battery (1000) decreases, and the internal resistance of the all-solid-state battery (1000) due to the negative electrode coating layer (220) increases, which may degrade the cycle characteristics of the cell. Meanwhile, although not illustrated, a carbon layer may be further included between the negative electrode coating layer (220) and the solid electrolyte layer (300) to improve adhesion.

[0149] A solid-state battery according to another embodiment may include a negative electrode active material layer corresponding to the negative electrode coating layer (220) described above. The negative electrode active material within the negative electrode active material layer may include a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide. A material capable of reversibly intercalating / deintercalating lithium ions may be a carbon-based negative electrode active material, such as crystalline carbon, amorphous carbon, or a combination thereof. Examples of crystalline carbon include graphite such as amorphous, plate-like, flake-like, spherical, or fibrous natural graphite or artificial graphite, and examples of amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, etc. As an alloy of lithium metal, an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn may be used. As a material capable of doping and undoping lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material may be used. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiOx (0 < x < 2), a Si-Q alloy (where Q is selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements (excluding Si), Group 15 elements, Group 16 elements, transition metals, rare earth elements, and combinations thereof), or a combination thereof. The Sn-based negative electrode active material may be Sn, SnO2, a Sn-based alloy, or a combination thereof. The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, it may include a secondary particle (core) assembled from primary silicon particles and an amorphous carbon coating layer (shell) located on the surface of the secondary particle.Amorphous carbon may also be located between silicon primary particles, for example, the silicon primary particles may be coated with amorphous carbon. Secondary particles may be dispersed within the amorphous carbon matrix. The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer located on the surface of the core. Si-based negative electrode active materials or Sn-based negative electrode active materials may be used in combination with carbon-based negative electrode active materials. Of course, other known negative electrode active materials may also be applied.

[0150]

[0151] FIG. 6 is intended to illustrate an all-solid-state battery (1000) according to another embodiment. Referring to FIG. 6, the all-solid-state battery (1000) according to one embodiment may further include a lithium metal layer (240) disposed between a negative electrode current collector (210) and a solid electrolyte layer (300) by charging. The all-solid-state battery (1000) according to one embodiment may further include a lithium metal layer (240) disposed between a negative electrode current collector (210) and a negative electrode coating layer (220) by charging. Although not shown in the drawing, the all-solid-state battery (1000) may further include a lithium metal layer (240) disposed between a solid electrolyte layer (300) and a negative electrode coating layer (220) by charging. Although not shown in the drawing, the all-solid-state battery (1000) may further include a lithium metal layer (240) disposed inside the negative electrode coating layer (220) by charging.

[0152] The lithium metal layer (240) may include lithium or a lithium alloy. Since the lithium metal layer (240) is a metal layer containing lithium, it may function as, for example, a lithium reservoir. The lithium alloy may be, for example, 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 (240) may be composed of one of these alloys or lithium, or may be composed of various types of alloys. The lithium metal layer (240) may be, for example, a plated layer. The lithium metal layer (240) may be deposited between the negative electrode coating layer (220) and the negative electrode current collector (210) during the charging process of the all-solid-state battery (1000), for example.

[0153] The thickness (d) of the lithium metal layer (240) 240 The thickness 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 of the lithium metal layer (240) is excessively thin, it may be difficult for the lithium metal layer (240) to perform the role of a lithium reservoir. If the thickness of the lithium metal layer (240) is excessively thick, the mass and volume of the all-solid-state battery (1000) increase, and the cycle characteristics of the all-solid-state battery (1000) may actually deteriorate.

[0154] In another embodiment, the lithium metal layer (240) within the negative electrode layer (200) may be provided, for example, between the negative electrode current collector (210) and the negative electrode coating layer (220) before assembly of the all-solid-state battery (1000). When the lithium metal layer (240) is placed between the negative electrode current collector (210) and the negative electrode coating layer (220) before assembly of the all-solid-state battery (1000), the lithium metal layer (240) acts as a lithium reservoir because it is a metal layer containing lithium. For example, a lithium foil may be placed between the negative electrode current collector (210) and the negative electrode coating layer (220) before assembly of the all-solid-state battery (1000).

[0155] When a lithium metal layer (240) is deposited by charging after assembly of the all-solid-state battery (1000), the energy density of the all-solid-state battery (1000) can be increased because the lithium metal layer (240) is not included during assembly of the all-solid-state battery (1000). When charging the all-solid-state battery (1000), it can be charged beyond the charging capacity of the negative electrode coating layer (220). That is, the negative electrode coating layer (220) is overcharged. At the beginning of charging, lithium can be absorbed in the negative electrode coating layer (220). When charging beyond the capacity of the negative electrode coating layer (220), lithium can be deposited, for example, between the negative electrode coating layer (220) and the negative electrode current collector (210). A lithium metal layer (230) can be formed by the deposited lithium.

[0156] The lithium metal layer (240) can be composed mainly of lithium (i.e., metallic lithium). During discharge, the lithium in the lithium metal layer (240) can be ionized and move to the positive electrode layer (100). In other words, lithium can be used as a negative electrode active material in the all-solid-state battery (1000). In addition, since the negative electrode coating layer (220) covers the lithium metal layer (240), the negative electrode coating layer (220) can protect the lithium metal layer (240) and simultaneously suppress the precipitation growth of lithium dendrites. Therefore, the negative electrode coating layer (220) can suppress short circuits and capacity degradation of the all-solid-state battery (1000) and improve the cycle characteristics of the all-solid-state battery (1000).

[0157] When a lithium metal layer (240) is formed by charging after assembly of the all-solid-state battery (1000), the negative electrode layer (200), that is, the negative electrode current collector (210) and the negative electrode 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 (1000).

[0158]

[0159] Referring to FIG. 7, an all-solid-state battery (1000) according to another embodiment may further include a thin film (230) containing an element capable of forming an alloy with lithium on a negative electrode current collector (210). The thin film (230) may be disposed between the negative electrode current collector (210) and the negative electrode coating layer (220). The thin film (230) may include, for example, an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium is, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., but is not necessarily limited to these, and any element capable of forming an alloy with lithium in the art is possible. The thin film (230) may be composed of one of these metals or an alloy of various types of metals.

[0160] By placing the thin film (230) on one side of the negative electrode current collector (210), the deposition pattern of the lithium metal layer (240) deposited between the thin film (230) and the negative electrode coating layer (220) is further flattened, and the cycle characteristics of the all-solid-state battery (1000) can be further improved.

[0161] The thickness (d) of the thin film (230) 230 The thickness of the thin film (230) 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 (230) is less than 1 nm, it may be difficult to perform the function of the thin film (230). If the thickness of the thin film (230) is excessively thick, the thin film (230) itself absorbs lithium, and the amount of lithium precipitated at the negative electrode decreases, which lowers the energy density of the all-solid-state battery (1000) and may lower the cycle characteristics of the all-solid-state battery (1000). The thin film (230) may be placed 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 (230) in the relevant technical field is possible.

[0162]

[0163] FIG. 8 is intended to illustrate an all-solid-state battery (1000) according to another embodiment. Referring to FIG. 8, an all-solid-state battery (1000) according to another embodiment has a width (W) of a positive electrode layer (100). 100 ) The width (W) of the cathode layer (200) 200 It may be smaller than ). In one embodiment, the all-solid-state battery (1000) has a width (W) of the negative electrode layer (200). 200The width of the solid electrolyte layer (300) and the width of the solid electrolyte layer (300) may have substantially the same area. An all-solid-state battery (1000) according to another embodiment may further include a gasket (400). The gasket (400) may be positioned to surround the positive electrode layer (100). The gasket (400) may fill the lateral step of the all-solid-state battery (1000) caused by the difference in width between the positive electrode layer (100) and the negative electrode layer (200). The gasket (400) may surround the four sides of the positive electrode layer (100). For example, the thickness of the gasket (400) may be substantially the same as the thickness of the positive electrode layer (100).

[0164]

[0165] FIG. 9 is intended to illustrate an all-solid-state battery (1000) according to another embodiment. Referring to FIG. 9, the solid electrolyte layer (300) of the all-solid-state battery (1000) according to one embodiment 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 positive electrode layer (100), and the second solid electrolyte layer (320) may be adjacent to the negative electrode layer (200). The thickness (d) of the first solid electrolyte layer (310) 310 ) is the thickness (d) of the second solid electrolyte layer (320). 320 It may be smaller than ). Referring to FIG. 9, the first solid electrolyte layer (310) according to one embodiment may have substantially the same width as the anode layer (100). The second solid electrolyte layer (320) may have substantially the same width as the cathode layer (200). The all-solid-state battery (1000) according to one embodiment may further include a gasket (400). Referring to FIG. 10, the gasket (400) may be arranged to surround the anode layer (100) and the first solid electrolyte layer (310).

[0166]

[0167] The creative idea is explained in more detail through the following examples and comparative examples. However, the examples are intended to illustrate the creative idea and do not limit the scope of the creative idea to these examples alone.

[0168]

[0169] Example 1: Uneven surface forming current collector / Carbon coating layer / Li2S-LiI-AlI3-CNF containing anode

[0170] Preparation of positive electrode active material

[0171] Li2S, LiI, and AlI3 were mixed in a weight ratio of 40:15:5. The mixture was mechanically milled using a ball mill to prepare a Li2S-LiI-AlI3 composite. The milling conditions were 25 ℃ and 600 rpm for 10 hours. The milling energy applied to the sample during milling was 28 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 600 rpm for 10 hours. The milling energy applied to the sample during milling was 28 G. The Li2S-LiI-AlI3-CNF composite thus prepared was used as the cathode active material.

[0172]

[0173] Manufacturing of anodes

[0174] Li6PS5Cl (D50 = 3.0 μm, crystalline), an argyrodite-type crystal, was prepared as the solid electrolyte. The positive active material and the solid electrolyte were prepared such that the weight ratio of the positive active material to the solid electrolyte was 70 to 30, respectively.

[0175] PTFE was prepared as a binder. An anode composite was prepared by mixing these materials in a weight ratio of (anode active material + solid electrolyte) : binder = 99 : 1. The anode composite was obtained by dry mixing using a ball mill.

[0176] A carbon coating layer composition was prepared by dispersing multilayer carbon nanotubes in an N-methyl-2-pyrrolidone solution (NMP). The content of multilayer carbon nanotubes in the total weight of the carbon coating layer composition is 10 wt%, and the content of NMP is 90 wt%.

[0177] A carbon coating layer composition was applied to the surface of an aluminum foil current collector with a thickness of about 20 μm, which serves as an anode current collector, and dried at a temperature of 120°C for 4 hours to form a carbon coating layer with a thickness of about 500 nm on the anode current collector. Since the NMP solvent evaporates through the drying process, the carbon coating layer can substantially be composed of multilayer carbon nanotube components.

[0178] The positive current collector used an aluminum foil with surface irregularities formed by electrochemical etching, and the average surface roughness (R) of one side of the positive current collector a ) is 0.3 μm.

[0179] An anode was prepared by placing the anode composite on one side of the carbon coating layer and plate pressing it for 10 minutes at a pressure of 200 MPa. The thickness of the anode was approximately 120 μm. The thickness of the anode active material layer was approximately 100 μm, and the areas of the anode active material layer, the carbon coating layer, and the anode current collector were the same.

[0180]

[0181] Manufacturing of the cathode

[0182] 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.

[0183] 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.

[0184]

[0185] Preparation of a solid electrolyte layer

[0186] 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.

[0187]

[0188] Manufacturing of all-solid-state batteries

[0189] Referring to Fig. 1, 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 at a pressure of 500 MPa for 30 minutes. This pressing treatment 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.

[0190] 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.

[0191]

[0192] Example 2: Uneven surface forming current collector / Carbon coating layer containing adhesive polymer / Li2S-LiI-AlI3-CNF containing anode

[0193] A dopamine buffer solution with a molar concentration of 0.001 to 0.05 M was prepared by combining tris(hydroxymethyl)aminomethane and methoxyphenol in distilled water. Here, polydopamine can be induced by adding an initiator to the dopamine buffer solution or by oxidizing the dopamine-containing dopamine buffer solution through mild heat treatment.

[0194] A positive electrode active material, a positive electrode, and an all-solid-state battery were prepared in the same manner as in Example 1, except that a carbon coating layer composition was prepared by mixing an N-methyl-2-pyrrolidone solution, a multilayer carbon nanotube, and a dopamine buffer solution in a weight ratio of 80:10:10.

[0195] In Example 2, since the NMP solvent is evaporated through the drying process, the carbon coating layer can substantially be composed of multilayer carbon nanotubes and polydopamine components.

[0196]

[0197] Example 3: Current collector / Carbon coating layer / Li2S-LiI-AlI3-CNF containing anode

[0198] A positive active material, a positive electrode, and an all-solid-state battery were prepared in the same manner as in Example 1, except that a positive current collector without irregularities was used.

[0199]

[0200] Example 4: Current collector / Carbon coating layer containing adhesive polymer / Li2S-LiI-AlI3-CNF containing anode

[0201] A positive active material, a positive electrode, and an all-solid-state battery were prepared in the same manner as in Example 2, except that a positive current collector without irregularities was used.

[0202]

[0203] Comparative Example 1: Uneven surface forming current collector / Li2S-LiI-AlI3-CNF containing anode

[0204] A positive active material, a positive electrode, and an all-solid-state battery were prepared in the same manner as in Example 1, except that a positive current collector without a carbon coating layer was used.

[0205]

[0206] Comparative Example 2: Uneven surface forming current collector / Carbon coating layer / Li2S-LiI-AlI3 containing anode

[0207] A positive electrode active material, a positive electrode, and an all-solid-state battery were prepared in the same manner as in Example 1, except that a Li2S-LiI-AlI3 composite was prepared by mixing Li2S, LiI, and AlI3 in a weight ratio of 40:15:5 without including CNF.

[0208]

[0209] Comparative Example 3: Uneven surface forming current collector / Carbon coating layer / Li2S-LiI-CNF containing anode

[0210] A positive electrode active material, a positive electrode, and an all-solid-state battery were prepared in the same manner as in Example 1, except that a Li2S-LiI composite was prepared by mixing Li2S and LiI in a weight ratio of 40:20 without including AlI3.

[0211]

[0212] Comparative Example 4: Uneven surface forming current collector / Carbon coating layer / Li2S-AlI3-CNF containing anode

[0213] A positive electrode active material, a positive electrode, and an all-solid-state battery were prepared in the same manner as in Example 1, except that a Li2S-AlI3 composite was prepared by mixing Li2S and AlI3 in a weight ratio of 40:20 without including LiI.

[0214]

[0215] The characteristics of the anodes prepared in Examples 1 to 4 and Comparative Examples 1 to 4 are shown in Table 1 below.

[0216] Positive electrode current collector positive electrode active material carbon coating layer Example 1 Application of AlLi2S-LiI-AlI3-CNF forming irregularities Example 2 Application of AlLi2S-LiI-AlI3-CNF forming irregularities (including adhesive polymer) Example 3 Application of AlLi2S-LiI-AlI3-CNF Example 4 Application of AlLi2S-LiI-AlI3-CNF (including adhesive polymer) Comparative Example 1 No application of AlLi2S-LiI-AlI3-CNF forming irregularities Comparative Example 2 Application of AlLi2S-LiI-AlI3 forming irregularities Comparative Example 3 Application of AlLi2S-LiI-CNF forming irregularities Comparative Example 4 Application of AlLi2S-AlI3-CNF forming irregularities

[0217] Evaluation Example 1: Scanning Electron Microscope (SEM) Analysis

[0218] The surface of the positive current collector used in Example 1 was observed using a scanning electron microscope (SEM). Fig. 11a is an SEM image of the positive current collector with irregularities formed in Example 1. Fig. 11b is an SEM image of the positive current collector with a carbon coating layer applied in Example 1.

[0219] Referring to FIGS. 11a and 11b, when a carbon coating layer is applied to an anode current collector having an uneven surface, it was confirmed that the carbon coating layer is applied in an irregular curvature shape on the surface having the uneven structure. As a result, it can be seen that carbon material having nanoparticle size is evenly filled in the indented portions of the uneven surface.

[0220]

[0221] Evaluation Example 2: Analysis of the anode cross-section

[0222] Scanning electron microscope (SEM) analysis was performed on each anode obtained according to Example 1.

[0223] SEM images of the anode cross-section used in Example 1 are shown in Fig. 12a.

[0224] Referring to FIG. 12a, it can be seen that a carbon coating layer with a thickness of approximately 500 nm is formed within the anode layer according to Example 1. The results of the EDS analysis of the cross-section of the carbon coating layer are shown in FIG. 12b. Referring to FIG. 12b, it can be seen that sulfur (S), iodine (I), aluminum (Al), and carbon (C) are present in the carbon coating layer. This indicates that a small amount of the Li2S-LiI-AlI3-CNF composite exists within the carbon coating layer due to the plate press process.

[0225]

[0226] Evaluation Example 3: Evaluation of Anode Adhesion

[0227] Test specimens were prepared by cutting the anodes obtained according to the examples and comparative examples into 25 mm x 100 mm pieces. Using a peel strength meter, the 180° peel strength between the current collector and the anode active material layer was measured at a temperature of 25°C with a peel speed of 100 mm / min and a measurement distance of 35 mm. The force required to peel 35 mm is listed in Table 2 below. The peel strength test was performed a total of two times, and the average value was presented.

[0228] Electrode Adhesion (gf / mm) Example 10.59 Example 20.65 Example 30.50 Example 40.55 Comparative Example 10.33 Comparative Example 20.49 Comparative Example 30.48 Comparative Example 40.49

[0229] Referring to Table 2, the anode peel strength of the comparative example is 0.33 to 0.49 gf / mm, whereas the anode peel strength of the example is 0.50 to 0.65 gf / mm, confirming that the adhesion of the anode active material layer to the current collector has been improved.

[0230]

[0231] Evaluation Example 4: Charge / Discharge Test

[0232] The charge-discharge characteristics of the all-solid-state batteries prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were evaluated by the following charge-discharge test.

[0233] 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 / CV mode. The battery voltage was charged to 2.8 V at 0.1C and the cut-off condition was set to 0.05C. Discharging was carried out in CC mode and proceeded to 1.0 V at 0.05C.

[0234] The charge and discharge capacities of the first cycle were measured while conducting a charge-discharge test once using the method described above. The discharge capacity of the first cycle was set as the standard capacity, and the initial efficiency was calculated using the following Equation 1.

[0235] <Mathematical Formula 1>

[0236] Initial Efficiency (%) = [Standard Capacity / 1st Cycle Charge Capacity] × 100 (%)

[0237] The discharge capacity of the 20th cycle was measured while conducting 20 charge-discharge tests using the method described above. The capacity retention rate was calculated using the following mathematical formula 2.

[0238] <Mathematical Formula 2>

[0239] Capacity Retention Rate (%) = [20th Cycle Discharge Capacity / Standard Capacity] × 100 (%)

[0240] The initial efficiency and capacity retention rate calculated through charge-discharge tests are shown in Table 3 below.

[0241] To measure the output characteristics (rate characteristics) of the all-solid-state batteries prepared in the above examples and comparative examples, a charge-discharge test was performed at 0.1C. The results are shown in Table 3 below.

[0242] Standard Capacity (mAh / g) Initial Efficiency (%) Rate Characteristic (0.1C / 0.05C, %) Capacity Retention Rate (@20 cycles, %) Example 19 2386.19 7.19 4.5 Example 29 2087.89 7.09 5.2 Example 39 1085.99 6.98 2.2 Example 49 0084.89 6.88 4.0 Comparative Example 17 09 72.68 0.55 9.1 Comparative Example 26 2071.57 5.07 0.2 Comparative Example 38 2083.19 2.07 6.2 Comparative Example 48 1683.19 1.27 4.2

[0243] As shown in Table 3, the all-solid-state battery employing the positive electrode of the example can be seen to have improved lifespan characteristics compared to the all-solid-state battery employing the positive electrode of the comparative example.

[0244] The all-solid-state battery according to the embodiment has an improved discharge capacity compared to the comparative example due to the improved adhesion between the positive current collector and the positive active material layer, and the capacity retention rate is improved as stable contact is maintained between the positive current collector and the positive active material layer without detachment of the positive active material even when charging and discharging are repeated during the cycle.

[0245]

[0246] Although embodiments of the creative idea have been described above with reference to the attached drawings, the creative idea may be implemented in other specific forms without altering its technical concept or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

1. Positive current collector; A carbon coating layer covering the surface of the anode current collector; and It includes an anode active material layer on the carbon coating layer above, The above positive active material layer comprises a composite and a solid electrolyte, and The above complex comprises sulfur-based materials, metal halide salts, and carbon-based materials, and The above metal halide salt comprises a first metal halide salt comprising an alkali metal and a second metal halide salt comprising a boron group metal, and One surface of the above positive current collector is in contact with the carbon coating layer, Cathode for all-solid-state batteries.

2. In Paragraph 1, One surface of the above positive current collector has an uneven structure, Cathode for all-solid-state batteries.

3. In Paragraph 1, Average surface roughness (R) of one side of the anode current collector a ) is 0.01 μm to 5.0 μm, Cathode for all-solid-state batteries.

4. In Paragraph 2, The depth (H) of the above uneven structure is 0.1% to 30% of the total thickness of the anode current collector. Cathode for all-solid-state batteries.

5. In Paragraph 1, The above positive current collector comprises aluminum (Al), nickel (Ni), stainless steel (SUS), indium (In), copper (Cu), magnesium (Mg), titanium (Ti), iron (Fe), cobalt (Co), zinc (Zn), germanium (Ge), lithium (Li), or a combination thereof. Cathode for all-solid-state batteries.

6. In Paragraph 1, The thickness of the carbon coating layer is 20 nm to 5 µm, Cathode for all-solid-state batteries.

7. In Paragraph 1, The carbon coating layer comprises carbon nanofibers (CNF), carbon nanotubes (CNT), graphene, and carbon black, or a combination thereof. Cathode for all-solid-state batteries.

8. In Paragraph 1, The carbon coating layer further comprises an adhesive polymer, and The above adhesive polymer comprises polydopamine, poly(3,4-ethylenedioxythiophene)((Poly(3,4-ethylenedioxythiophene; PEDOT) polyanilines (PANI), polyacrylate, cation-substituted polycarboxylic acid, cation-substituted polycarboxylic acid copolymer, polynorepinephrine, poly(meth)acrylamide, polyvinyl alcohol, polyhydroxyethyl(meth)acrylate, polymethyl(meth)acrylate-(meth)acrylic acid copolymer, polymethyl(meth)acrylate, poly(meth)acrylic acid), styrene-(meth)acrylic acid) copolymer, or a combination thereof. Cathode for all-solid-state batteries.

9. In Paragraph 8, The content of the adhesive polymer is 30 to 80 weight% with respect to the total weight of the carbon coating layer, Cathode for all-solid-state batteries.

10. In Paragraph 1, The above solid electrolyte includes a sulfide-based solid electrolyte, and The above sulfide-based solid electrolyte is Li 7-a M a-1 PS 6-c X c It includes an argyrodite-type compound represented by (1≤a≤2, 0≤c≤2), and The above X is F, Br, Cl, or a combination thereof, and The above M is candium (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, Cathode for all-solid-state batteries.

11. In Paragraph 1, The first metal halide salt comprises LiI, LiF, LiCl, LiBr, or a combination thereof. Cathode for all-solid-state batteries.

12. In Paragraph 1, The second metal halide salt comprises AlI3, AlF3, AlCl3, AlBr3, GaF3, GaCl3, GaBr3, GaI3, InF3, InCl3, lnBr3, lnI3, TiF3, TiCl3, TiBr3, TiI3, or a combination thereof. Cathode for all-solid-state batteries.

13. In Paragraph 1, The above carbon-based material includes carbon nanostructures, and The above carbon nanostructure comprises carbon nanofibers (CNF), carbon nanotubes (CNT), carbon nanobelts, carbon nanorods, or a combination thereof. Cathode for all-solid-state batteries.

14. In Paragraph 1, The above complex is, The content of the sulfur-based material is 20% to 80% by weight based on the total weight of the composite, and The content of the metal halide salt is 10% to 60% by weight based on the total weight of the composite, and The content of the carbonaceous material is 1% to 30% by weight with respect to the total weight of the composite, Cathode for all-solid-state batteries.

15. In Paragraph 1, The above positive active material layer further includes a binder, and The binder comprises polytetrafluoroethylene (PTFE), polyvinylidene fluoride, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, or a combination thereof. Cathode for all-solid-state batteries.

16. Positive current collector; A carbon coating layer covering the surface of the anode current collector; and It includes an anode active material layer on the carbon coating layer above, The above positive active material layer comprises a first composite and a solid electrolyte, and The carbon coating layer above includes a second composite, and Each of the first and second complexes above comprises a sulfur-based material, a metal halide salt, and a carbon-based material, and The above metal halide salt comprises a first metal halide salt comprising an alkali metal and a second metal halide salt comprising a boron group metal. Cathode for all-solid-state batteries.

17. In Paragraph 16, Each of the above first and second complexes is, The content of the sulfur-based material is 20% to 80% by weight based on the total weight of the composite, and The content of the metal halide salt is 10% to 60% by weight based on the total weight of the composite, and The content of the carbonaceous material is 1% to 30% by weight with respect to the total weight of the composite, Cathode for all-solid-state batteries.

18. In Paragraph 16, The content of the second composite is 1% to 20% by weight with respect to the total weight of the carbon coating layer. Cathode for all-solid-state batteries.

19. A positive electrode; a negative electrode; and a solid electrolyte layer disposed between the positive electrode and the negative electrode, The above anode comprises an anode according to any one of claims 1 to 18, All-solid-state battery.

20. In Paragraph 19, The above cathode is: cathode current collector; and A cathode coating layer disposed on the above-mentioned cathode current collector, comprising: The above cathode coating layer comprises a carbon-based material and silver particles, All-solid-state battery.

Images