All-solid-state battery and manufacturing method therefor

Abstract

The present invention relates to an all-solid-state battery and an all-solid-state battery manufacturing method therefor, and, more specifically, the all-solid-state battery may comprise: a cathode including a cathode current collector and a cathode active material layer; an anode including an anode current collector and an anode coating layer; a solid electrolyte layer disposed between the cathode and the anode; and an adsorption layer on the cathode current collector and / or the anode current collector. The cathode active material layer includes a sulfide-based cathode active material, the cathode current collector and / or the anode current collector has at least one hole capable of discharging hydrogen sulfide, and the adsorption layer can adsorb hydrogen sulfide.

Description

All-solid-state battery, and method of manufacturing the same

[0001] The present invention relates to an all-solid-state battery and a method for manufacturing the same, and more specifically, to an all-solid-state battery comprising an adsorption layer that adsorbs hydrogen sulfide.

[0002]

[0003] Recently, driven by industrial demands, the development of batteries with high energy density and safety is actively underway. For example, lithium-ion batteries are being commercialized not only in the fields of information and communication devices but also in the automotive sector. In the automotive sector, safety is considered particularly important because it is directly related to human life.

[0004] Meanwhile, currently commercially available lithium-ion batteries contain an electrolyte containing a flammable organic dispersion medium, which poses a risk of overheating and fire in the event of a short circuit. Considering these issues, all-solid-state batteries are being proposed in which the electrolyte is replaced with a solid electrolyte. By not using a flammable organic dispersion medium, all-solid-state batteries can significantly reduce the likelihood of fire or explosion even if a short circuit occurs. Therefore, these all-solid-state batteries can significantly improve safety compared to lithium-ion batteries that use an electrolyte.

[0005]

[0006] The problem that the present invention aims to solve is to provide an all-solid-state battery with long lifespan and high rate characteristics.

[0007] Another problem that the present invention aims to solve is to provide a method for manufacturing an all-solid-state battery that achieves long lifespan and high rate characteristics.

[0008]

[0009] According to the concept of the present invention, an all-solid-state battery comprises: a positive electrode including a positive current collector and a positive active material layer; a negative electrode including a negative current collector and a negative coating layer; a solid electrolyte layer disposed between the positive electrode and the negative electrode; and an adsorption layer on at least one of the positive current collector and the negative current collector, wherein the positive active material layer may comprise a sulfide-based positive active material. At least one of the positive current collector and the negative current collector has at least one hole configured to allow hydrogen sulfide to be discharged, and the adsorption layer may be configured to adsorb hydrogen sulfide.

[0010] A method for manufacturing an all-solid-state battery according to the concept of the present invention may include: forming a positive electrode comprising a positive current collector and a positive active material layer; forming a negative electrode comprising a negative current collector and a negative coating layer; and forming at least one hole configured to allow hydrogen sulfide to be discharged in at least one of the positive current collector and the negative current collector. A solid electrolyte layer is disposed between the positive electrode and the negative electrode to form a cell stack; and an adsorption layer is formed on at least one of the positive current collector and the negative current collector of the cell stack, wherein the adsorption layer may be configured to adsorb hydrogen sulfide.

[0011]

[0012] The all-solid-state battery according to the present invention includes an adsorption layer that absorbs hydrogen sulfide gas and expands to prevent pressure drop and short circuits inside the cell, thereby improving the increase in inter-particle network interface resistance caused by hydrogen sulfide generation and reduction in active material size. Consequently, the all-solid-state battery according to the present invention can achieve long lifespan and high rate characteristics.

[0013]

[0014] FIG. 1 is a plan view of an all-solid-state battery according to one embodiment.

[0015] FIG. 2 is a cross-sectional view along line A-A' of FIG. 1 of an all-solid-state battery unit cell according to one embodiment.

[0016] FIG. 3 is a cross-sectional view illustrating a positive active material layer according to one embodiment of the present invention.

[0017] FIG. 4 is a cross-sectional view of an all-solid-state battery unit cell after a cycle according to one embodiment.

[0018] FIG. 5 is a cross-sectional view of an all-solid-state battery unit cell according to another embodiment.

[0019] FIG. 6 is a cross-sectional view of an all-solid-state battery bicell according to one embodiment.

[0020] FIG. 7 is a cross-sectional view of a pouch-type all-solid-state battery according to another embodiment.

[0021] Figure 8 is a cross-sectional view of an all-solid-state battery unit cell after cycling according to a comparative example.

[0022] FIG. 9 is a flowchart illustrating a method for manufacturing an all-solid-state battery according to embodiments of the present invention.

[0023]

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] Unless otherwise defined in this specification, the particle size may be the average particle size. Additionally, the particle size refers to the average particle size (D50), which means the diameter of the particle whose cumulative volume in the particle size distribution is 50% by volume. The average particle size (D50) may be measured by methods widely known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope (TEM) image or a scanning electron microscope (SEM) image. Alternatively, the average particle size (D50) value may be obtained by measuring using a measuring device utilizing dynamic light scattering, performing data analysis to count the number of particles for each particle size range, and then calculating from this. Alternatively, it may be measured using a laser diffraction method. When measuring by laser diffraction, more specifically, after dispersing the particles to be measured in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasound of about 28 kHz at an output of 60 W, and then the average particle size (D50) at 50% of the particle size distribution in the measuring device can be calculated.

[0029] In this specification, “metal” includes both metals and metalloids, such as silicon and germanium, in their elemental or ionic states. In this specification, “alloy” means a mixture of two or more metals. In this specification, “electrode active material” means an electrode material capable of undergoing lithiation and delithiation. In this specification, “anode active material” means an anode material capable of undergoing lithiation and delithiation. In this specification, “cathode active material” means a cathode material capable of undergoing lithiation and delithiation. In this specification, “lithiation” and “to lithiate” mean the process of adding lithium to an electrode active material. In this specification, “delithiation” and “to delithiate” mean the process of removing lithium from an electrode active material. In this specification, “charge” and “to charge” mean the process of providing electrochemical energy to a battery. In this specification, “discharge” and “to discharge” mean the process of removing electrochemical energy from a battery. In this specification, “anode” and “cathode” refer to electrodes where electrochemical reduction and lithiation occur during the discharge process. In this specification, “negative electrode” and “anode” refer to electrodes where electrochemical oxidation and delithiation occur during the discharge process.

[0030] FIG. 1 is a plan view of an all-solid-state battery according to one embodiment. FIG. 2 is a cross-sectional view of an all-solid-state battery unit cell according to one embodiment, taken along line A-A' of FIG. 1. FIG. 3 is a cross-sectional view illustrating a positive electrode active material layer according to one embodiment of the present invention.

[0031] Referring to FIGS. 1 and 2, the all-solid-state battery (10) according to the present invention may include a positive electrode layer (100), a negative electrode layer (200) facing the positive electrode layer (100), and a solid electrolyte layer (300) disposed between the positive electrode layer (100) and the negative electrode layer (200). However, not limited thereto, the all-solid-state battery (10) may further include an additional functional layer, such as an adhesion-enhancing layer, disposed between the positive electrode layer (100) and the solid electrolyte layer (300) or between the negative electrode layer (200) and the solid electrolyte layer (300).

[0032] An anode layer (100) according to one embodiment of the present invention may include an anode current collector (110) and an anode active material layer (120) disposed on the anode current collector (110). The anode active material layer (120) may include an anode active material, a solid electrolyte, a conductive material, and a binder.

[0033] The positive current collector (110) may provide a reference surface on which the positive active material layer (120) is disposed. The positive current collector (110) may include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. The positive current collector (110) may include a plate or a foil. In another embodiment of the present invention, the positive current collector (110) may be omitted. The thickness of the positive current collector (110) may be, for example, 1 μm to 100 μm, 1 μm to 50 μm, 5 μm to 25 μm, or 10 μm to 20 μm.

[0034] The positive current collector (110) may include, for example, a base film and a metal layer disposed on one or both sides of the base film. The base film may include, for example, a polymer. The polymer may be, for example, a thermoplastic polymer. The polymer may include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof.

[0035] The base film may be, for example, an insulator. Since the base film contains an insulating thermoplastic polymer, the base film may soften or liquefy upon the occurrence of a short circuit, thereby interrupting battery operation and suppressing a sudden increase in current.

[0036] The metal layer may include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), or alloys thereof. The metal layer may act as an electrochemical fuse and cut off in the event of an overcurrent to perform a short-circuit prevention function. The limit current and maximum current can be controlled by adjusting the thickness of the metal layer. The metal layer may be plated or deposited on a base film. As the thickness of the metal layer decreases, the limit current and / or maximum current of the positive current collector (110) decreases, thereby improving the stability of the lithium battery in the event of a short circuit.

[0037] A lead tab may be added to the metal layer for external connection. The lead tab may be welded to the metal layer or the metal layer / base film laminate by ultrasonic welding, laser welding, spot welding, etc. During welding, the base film and / or metal layer melt, allowing the metal layer to be electrically connected to the lead tab.

[0038] To make the weld between the metal layer and the lead tab more robust, a metal chip may be added between the metal layer and the lead tab. The metal chip may be a thin sheet of the same material as the metal of the metal layer. The metal chip may be, for example, metal foil, metal mesh, etc. The metal chip may be, for example, aluminum foil, copper foil, SUS foil, etc. The lead tab may be welded to a metal chip / metal layer laminate or a metal chip / metal layer / base film laminate by placing the metal chip on the metal layer and then welding it to the lead tab. During welding, as the base film, metal layer, and / or metal chip melt, the metal layer or the metal layer / metal chip laminate may be electrically connected to the lead tab. A metal chip and / or lead tab may be added to a portion of the metal layer.

[0039] The thickness of the base film may be, for example, 1 to 50 μm, 1.5 to 50 μm, 1.5 to 40 μm, or 1 to 30 μm. By having the base film within this thickness range, the weight of the electrode assembly can be reduced more effectively. The melting point of the base film may be, for example, 100 to 300 °C, 100 to 250 °C or lower, or 100 to 200 °C. By having the base film within this melting point range, the base film can melt during the welding process of the lead tab and be easily bonded to the lead tab. Surface treatments, such as corona treatment, may be performed on the base film to improve the adhesion between the base film and the metal layer.

[0040] The thickness of the metal layer may be, for example, 0.01 to 3 μm, 0.1 to 3 μm, 0.1 to 2 μm, or 0.1 to μm. By having the metal layer within this range of thickness, the stability of the electrode assembly can be ensured while maintaining conductivity. The thickness of the metal piece may be, for example, 2 to 10 μm, 2 to 7 μm, or 4 to 6 μm. By having the metal piece within this range of thickness, the connection between the metal layer and the lead tab can be performed more easily. Since the positive current collector (110) has a laminated structure of the base film and the metal layer described above, the weight of the positive layer (100) can be reduced, and consequently, the energy density of the all-solid-state battery (10) can be improved.

[0041] In one embodiment of the present invention, the content of the positive active material in the positive active material layer (120) may be 10 wt% to 99 wt%, 30 wt% to 80 wt%, 40 wt% to 70 wt%, or 40 wt% to 50 wt% of the total weight of the positive active material layer (120). If the content of the positive active material is reduced excessively, the energy density of the all-solid-state battery (10) may decrease. If the content of the positive active material is increased excessively, the degradation of the all-solid-state battery (10) may be accelerated due to changes in the volume of the positive during charging and discharging.

[0042] The positive active material within the positive active material layer (120) can reversibly absorb and desorb lithium ions. The positive active material may include a plurality of particles. The positive active material according to the present invention may include an oxide-based positive active material, a sulfide-based positive active material, or a combination thereof.

[0043] The oxide-based cathode active material may include, for example, lithium transition metal oxides, metal oxides, or combinations thereof. Lithium transition metal oxides include, for example, lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt mangense oxide, lithium manganate, lithium iron phosphate, or combinations thereof. Lithium oxides may include, for example, iron oxide, vanadium oxide, or combinations thereof.

[0044] Sulfide-based cathode active materials may include, for example, nickel sulfide, copper sulfide, Li2S, Li2S-containing complexes, or combinations thereof. A more specific description of the sulfide-based cathode active material according to an embodiment of the present invention will be provided later.

[0045] For oxide-based cathode active materials, one or more types of composite oxides of lithium and a metal selected from, for example, cobalt, manganese, nickel, and combinations thereof may be used. For lithium-containing oxide-based cathode active materials, for example, Li a A 1-b B' b D2(wherein 0.90 ≤ a ≤ 1, and 0 ≤ b ≤ 0.5); Li a E 1-b B' b O 2-c D c (In the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE 2-b B' b O4-c D c (In the above equation, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b B' c D α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Co b B' c O 2-α F' α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Co b B' c O 2-α F' α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B' c D α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Mn b B' c O 2-α F' α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B' c O 2-α F' α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni b E c Gd O2(wherein 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d G e O2(wherein 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li a NiG b O2(in the above equation, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a CoG b O2(in the above equation, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a MnG b O2(in the above equation, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4(wherein 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); LiV2O5; LiI'O2; LiNiVO4; Li (3-f) J2(PO4)3(0 ≤ f ≤ 2); Li (3-f) It may include a compound represented by any one of the chemical formulas of Fe2(PO4)3(0 ≤ f ≤ 2); LiFePO4.

[0046] In the chemical formula representing the compound described above, A is Ni, Co, Mn, or a combination thereof; B' is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F' is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I' is Cr, V, Fe, Sc, Y, or a combination thereof; and J may be V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0047] The oxide-based cathode active material may include, for example, a lithium salt of a transition metal oxide having a layered rock salt type structure among the lithium transition metal oxides described above. The "layered rock salt type structure" is, for example, a cubic rock salt type structure. <111> It is a structure in which oxygen and metal atomic layers are alternately and regularly arranged in a specific direction, thereby forming a two-dimensional plane for each atomic layer. The "cubic rock salt type structure" represents a sodium chloride (NaCl) type structure, which is a type of crystal structure; specifically, it exhibits a structure in which face-centered cubic lattices (fcc) formed by cations and anions, respectively, are offset from each other by half the ridge of the unit lattice. Lithium transition metal oxides having such a layered rock salt type structure are, for example, LiNi x Co y Al z O2(NCA) or LiNi x Co y Mn zO2(NCM) (0 <x<1,0<y<1, 0<z<1, x+y+z=1) 등의 삼원계 리튬전이금속산화물일 수 있다. 양극 활물질이 층상암염형 구조를 갖는 삼원계 리튬전이금속산화물을 포함하는 경우, 전고체 전지(10)의 에너지 밀도가 커지고 열안정성이 향상될 수 있다.

[0048] The oxide-based cathode active material may be covered by a coating layer (not shown). The oxide-based cathode active material may also be used as a mixture of the compound described above and the compound to which the coating layer is added. Meanwhile, the coating layer added to the surface of the cathode active material may include, for example, oxides, hydroxides, oxyhydroxides, oxycarbonates, or hydroxycarbonates of the following coating elements. The compounds forming this coating layer are amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer may include, for example, Li2O-ZrO2 (LZO). The method for forming the coating layer may be selected within a range that does not adversely affect the physical properties of the cathode active material. Examples of methods for forming the coating layer include spray coating and immersion methods.

[0049] When the oxide-based cathode active material contains nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, for example, the capacity density of the all-solid-state battery (10) is increased, and the metal leaching of the cathode active material in the charged state can be reduced. As a result, the cycle characteristics of the all-solid-state battery (10) in the charged state are improved. Meanwhile, "cycle characteristics" is a characteristic that indicates the degree of deterioration of the all-solid-state battery (10) due to charging and discharging of the all-solid-state battery (10). An all-solid-state battery (10) with high cycle characteristics has a small degree of deterioration due to charging and discharging, while an all-solid-state battery (10) with low cycle characteristics may have a large degree of deterioration due to charging and discharging.

[0050] The oxide-based cathode active material may have a particle shape such as a sphere or an ellipsoid. The particle size and content of the oxide-based cathode active material are not particularly limited. The size of the oxide-based cathode active material may be, for example, 0.1 to 30 μm, 0.5 to 20 μm, or 1 to 15 μm. The oxide-based cathode active material may be, for example, single-crystal particles or polycrystalline particles.

[0051] The positive active material layer (120) according to embodiments of the present invention may include a sulfide-based positive active material. Specifically, with reference to FIG. 3, the sulfide-based positive active material may include a Li2S-containing positive active material (CAC). The Li2S-containing positive active material (CAC) may include, for example, a composite of Li2S and carbon, a composite of Li2S, carbon and a solid electrolyte, a composite of Li2S and a solid electrolyte, a composite of Li2S and a lithium salt, a composite of Li2S, a lithium salt and carbon, a composite of Li2S, a lithium salt, a metal halide and carbon, a composite of Li2S and a metal carbide, a composite of Li2S, carbon and a metal carbide, a composite of Li2S and a metal nitride, a composite of Li2S, carbon and a metal nitride, or a combination thereof.

[0052] The cathode active material (CAC) may include a sulfide-based composite (CAM) and a conductive material (CMA). In one embodiment, the sulfide-based composite (CAM) may have a particle shape such as a perfect spherical or elliptical sphere. The particle size of the sulfide-based composite (CAM) is not particularly limited and may be within a range applicable to general cathode active materials. The size of the sulfide-based composite (CAM) may be, for example, 0.1 to 50 μm, 0.5 to 30 μm, 0.5 to 20 μm, or 1 to 10 μm. The conductive material (CMA) may cover the surface of the sulfide-based composite (CAM).

[0053] The conductive material (CMA) may include carbon. The conductive material (CMA) may include, without limitation, materials containing carbon atoms that are used as conductive materials in the art. For example, the conductive material (CMA) may include crystalline carbon, amorphous carbon, or a combination thereof. The conductive material (CMA) may include, for example, a sintered product of a carbon precursor. The conductive material (CMA) may include, for example, carbon nanostructures.

[0054] The conductive material (CMA) may include, for example, porous carbon or non-porous carbon. The porous carbon may include, for example, periodic and regular two-dimensional or three-dimensional pores. The porous carbon may be, for example, carbon black such as Ketjen black, acetylene black, Denka black, thermal black, channel black; graphite, activated carbon, or a combination thereof. The form of the carbon within the conductive material (CMA) may be, for example, in particle form, sheet form, fibrous form, etc., but is not limited thereto and may be any form of carbon used in the relevant art.

[0055] In one embodiment of the present invention, the conductive material (CMA) may include a fibrous carbon-based material. By including the fibrous carbon-based material in the conductive material (CMA), the electron conductivity of the positive electrode active material (CAC) can be further improved. By including the fibrous carbon-based material in the conductive material (CMA), electron conduction from the surface to the interior of the positive electrode active material (CAC) can be performed more easily. The internal resistance of the sulfide-based composite (CAM) is reduced by the conductive material (CMA), and the cycle characteristics of the secondary battery can be further improved.

[0056] 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 an aspect ratio within this range, the overall electron conductivity of the cathode active material (CAC) is improved, and the imbalance of local electron conductivity within the cathode active material (CAC) can be further alleviated.

[0057] Fibrous carbon-based materials may include, for example, carbon nanostructures. Carbon nanostructures may include, for example, carbon nanofibers (CNF), carbon nanotubes (CNT), carbon nanobelts, carbon nanorods, or combinations thereof. Carbon nanostructures may form a primary carbon nanostructure composed of a single carbon nanostructure and a secondary carbon nanostructure formed by the aggregation of multiple carbon nanostructures.

[0058] The diameter of the primary carbon nanostructure may be, for example, 1 nm to 200 nm, 1 nm to 150 nm, 1 nm to 100 nm, 1 nm to 50 nm, 1 nm to 30 nm, or 1 nm to 20 nm. The length of the primary carbon nanostructure may be, for example, 10 nm to 2 µm, 10 nm to 1.5 µm, 10 nm to 1 µm, 10 nm to 500 nm, 10 nm to 400 nm, 10 nm to 300 nm, 10 nm to 200 nm, or 10 nm to 100 nm. The diameter and length of the primary carbon nanostructure may be measured from scanning electron microscope (SEM) or transmission electron microscope (TEM) images. Alternatively, the diameter and / or length of the primary carbon nanostructure may be measured by laser diffraction.

[0059] The secondary carbon nanostructure may be a structure formed by assembling primary carbon nanostructures, for example, to form a bundle or rope type, either wholly or partially. The secondary carbon nanostructure may include, for example, bundle-type carbon nanostructures, rope-type carbon nanostructures, or a combination thereof. The diameter of the secondary carbon nanostructure may be, for example, 2 nm to 200 nm, 3 nm to 150 nm, 5 nm to 100 nm, 5 nm to 50 nm, 5 nm to 30 nm, or 5 nm to 20 nm. The length of the secondary carbon nanotube structure may be, for example, 20 nm to 2 µm, 30 nm to 1.5 µm, 50 nm to 1 µm, 50 nm to 500 nm, 50 nm to 400 nm, 50 nm to 300 nm, 50 nm to 200 nm, or 50 nm to 100 nm or more. The diameter and length of the secondary carbon nanostructure can be measured from scanning electron microscope (SEM) images or optical microscopes. Alternatively, the diameter and / or length of the secondary carbon nanostructure can be measured by laser diffraction. The secondary carbon nanostructure can be converted into a primary carbon nanostructure by dispersing it in a solvent, for example, and then used to manufacture a cathode active material (CAC).

[0060] The method for manufacturing the cathode active material (CAC) according to the embodiments may be a dry method, a wet method, or a combination thereof, but is not limited thereto. In the art, the method for manufacturing the cathode active material (CAC) may be, for example, milling, heat treatment, deposition, etc., but is not necessarily limited thereto, and any method used in the art may be possible.

[0061] In one embodiment of the present invention, the sulfide-based composite (CAM) within the cathode active material (CAC) may comprise a composite of Li2S and a solid electrolyte. The solid electrolyte may be, for example, an amorphous solid electrolyte, any material used as an ion-conducting material in the art. The solid electrolyte may be, for example, an inorganic solid electrolyte. The solid electrolyte may be, for example, a crystalline solid electrolyte, an amorphous solid electrolyte, or a combination thereof. The solid electrolyte may be, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a combination thereof. The sulfide-based solid electrolyte may include, for example, Li, S, and P, and may optionally further include a halogen element. The sulfide-based solid electrolyte may be selected from among sulfide-based solid electrolytes used in the solid electrolyte layer. The sulfide-based solid electrolyte may be, for example, 1 × 10⁻⁶ at room temperature. -5 It can have an ionic conductivity of S / cm or higher. Sulfide-based solid electrolytes are, for example, Li3PO4-Li2SO4, Li2S-P2S5, Li2S-P2S5-LiX, where X is a halogen element, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n , m, n are positive numbers, Z is one of Ge, Zn, or Ga, Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q , p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, In, Li 7-x PS 6-x Cl x , 0≤x≤2, Li 7-x PS 6-x Br x , 0≤x≤2, and Li 7-x PS6-x I x It may include one or more selected from , 0≤x≤2.

[0062] Oxide-based solid electrolytes contain, for example, Li, O, and transition metal elements, and may optionally contain other elements. Oxide-based solid electrolytes contain, for example, 1×10⁻⁶ at room temperature. -5 The solid electrolyte may have an ionic conductivity of S / cm or higher. The oxide-based solid electrolyte may be selected from among oxide-based solid electrolytes used in the solid electrolyte layer. The solid electrolyte may be, for example, a mixture of a sulfide-based solid electrolyte and a lithium salt. For example, it may be a mixture of Li3PO4-Li2SO4 and a binary lithium salt or a mixture of Li3PO4-Li2SO4 and a ternary lithium salt.

[0063] In one embodiment of the present invention, the sulfide-based complex (CAM) in the cathode active material (CAC) may include a complex of Li2S and a lithium salt. In other words, the complex (CAM) may include a compound of Li2S and a lithium salt. The lithium salt compound may not include, for example, sulfur (S) atoms.

[0064] The lithium salt compound may be a binary compound composed of, for example, lithium and one element selected from groups 13 to 17 of the periodic table. The binary compound may include, for example, one or more selected from LiF, LiCl, LiBr, LiI, LiH, Li2S, Li2O, Li2Se, Li2Te, Li3N, Li3P, Li3As, Li3Sb, LiI3, and LiB3. The lithium salt compound may be a ternary compound composed of, for example, lithium and two elements selected from groups 13 to 17 of the periodic table. The ternary compound may include, for example, one or more selected from Li3OCl, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiNO3, Li2CO3, LiBH4, Li2SO4, Li3BO3, Li3PO4, Li4NCl, Li5NCl2, and Li3BN2. For example, the lithium salt compound may be one or more lithium halide compounds selected from LiF, LiCl, LiBr, and LiI.

[0065] In one embodiment of the present invention, the sulfide-based complex (CAM) may comprise a complex of Li2S and a metal carbide. The metal carbide may be, for example, a two-dimensional metal carbide. The two-dimensional metal carbide may be, for example, MXene. The two-dimensional metal carbide is, for example, M n+1 C n T x It can be expressed as (M is a transition metal, T is a terminal group, T is O, OH and / or F, n=1, 2, or 3, and x is the number of terminal groups). Two-dimensional metal carbides are, for example, Ti2CT x , (Ti 0.5 , Nb 0.5 )2CT x , Nb2CT x , V2CT x , Ti3C2T x , (V 0.5 , Cr 0.5)3C2T x , Ti3CNT x , Ta4C3T x , Nb4C3T x Or it may be a combination of these. The surface of the two-dimensional metal carbide may be terminated with O, OH and / or F.

[0066] In one embodiment of the present invention, the sulfide-based complex (CAM) may comprise a complex of Li2S and a metal nitride. The metal nitride may be, for example, a two-dimensional metal nitride. The two-dimensional metal nitride is, for example, M n+1 N n T x It can be expressed as (M is a transition metal, T is a terminal group, T is O, OH and / or F, n=1, 2, or 3, and x is the number of terminal groups). The surface of a two-dimensional metal nitride can be terminated with O, OH and / or F.

[0067] A cathode active material (CAC) and a composite (CAM) containing Li2S according to one embodiment of the present invention will be described in more detail. The cathode active material (CAC) may comprise a composite of Li2S, a lithium salt, and carbon. More specifically, the cathode active material (CAC) may comprise a composite of Li2S, a lithium halide, and carbon.

[0068] The composite (CAM) according to the embodiments may have ductility. The composite (CAM) may function as a buffer material within the positive active material layer (120). The composite (CAM) may prevent the occurrence of defects due to volume changes in the positive active material layer (120).

[0069] A composite (CAM) according to one embodiment is Li2S-Li a X bIt may include a compound represented by (1≤a≤5, 1≤b≤5). X may be I, Br, Cl, F, H, O, Se, Te, N, P, As, Sb, Al, B, OCl, PF6, BF4, SbF6, AsF6, ClO4, AlO2, AlCl4, NO3, CO3, BH4, SO4, BO3, PO4, NCl, NCl2, BN2, or a combination thereof. a may be, for example, 1, 2, 3, 4, or 5. b may be, for example, 1, 2, 3, 4, or 5.

[0070] In one embodiment, the composite (CAM) may include a solid solution of Li2S and a lithium salt. The ionic conductivity of the composite (CAM) may be improved by including the solid solution of Li2S and a lithium salt. For example, the ionic conductivity of the solid solution of Li2S and a lithium salt may be improved compared to the ionic conductivity of Li2S by including lithium ions disposed within the Li2S crystallites. Consequently, the composite (CAM) according to the present invention may have high ionic conductivity and low internal resistance. The cycle characteristics of an all-solid-state secondary battery including the composite (CAM) of the present invention may be improved.

[0071] The size of the Li2S crystallites of the composite (CAM) obtained from the XRD spectrum may be, for example, 20 nm or less, 15 nm or less, or 10 nm or less. The size of the Li2S crystallites of the composite (CAM) obtained from the XRD spectrum may be, for example, 1 to 20 nm, 1 to 15 nm, or 3 to 10 nm. As the size of the Li2S crystallites decreases, the contact area between Li2S and the lithium salt may increase. As the contact area between Li2S and the lithium salt increases, the ionic conductivity of the composite of Li2S and the lithium salt may be improved.

[0072] A composite (CAM) according to one embodiment may further include a metal halide. In other words, the composite (CAM) may include a composite of Li2S, a lithium salt, and a metal halide. The metal halide may contain a metal other than lithium.

[0073] The complex (CAM) is Li2S-Li a X1 b -MX2 c It may include a compound represented by . a may be an integer between 1 and 5, b may be an integer between 1 and 5, and c may be an integer between 1 and 5. M may be selected from the group consisting of aluminum (Al), silver (Ag), gold (Au), platinum (Pt), palladium (Pd), bismuth (Bi), tin (Sn), and zinc (Zn). X1 and X2 may each be selected from the group consisting of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0074] The composite (CAM) may include a solid solution of Li2S, a lithium salt, and a metal halide. As an example, the composite (CAM) may include a compound (or solid solution) represented as Li2S-LiI-AlI3. As described above, the composite (CAM) and the conductive material (CMA, e.g., a carbon nanostructure) may constitute a cathode active material (CAC) according to the present invention.

[0075] The Mohs hardness of the composite (CAM) may be lower than that of the lithium salt. The composite (CAM) may have improved ductility compared to the lithium salt. By having improved ductility, internal defects caused by volume changes in the positive active material layer (120) can be effectively prevented.

[0076] The Mohs hardness of Li2S is, for example, 0.6. The Mohs hardness of the composite (CAM) may be, for example, less than 2, 1.5 or less, 1 or less, or 0.7 or less. If the Mohs hardness of the composite (CAM) increases excessively, it may be difficult to provide ductility.

[0077] The Mohs hardness of the lithium salt may be 0.7 or higher, 0.8 or higher, 0.9 or higher, 1.0 or higher, 1.5 or higher, or 2.0 or higher. For example, the Mohs hardness of LiI is 2.0. Since the lithium salt has a Mohs hardness in this range, the grinding of Li2S can be performed more easily during the milling process, and a solid solution of Li2S and the lithium salt can be formed more easily.

[0078] Since Li2S has relatively low ionic conductivity, a complex can be formed between Li2S and a lithium salt to improve ionic conductivity. A complex (CAM) formed between Li2S and a lithium salt can have improved ionic conductivity compared to Li2S alone. The content of Li2S in the complex (CAM) can be 50 wt% to 95 wt%, 50 wt% to 90 wt%, 50 wt% to 80 wt%, or 50 wt% to 70 wt% of the total weight of the complex (CAM). By having a Li2S content within this range, the complex (CAM) can simultaneously possess improved ionic conductivity and excellent ductility.

[0079] The content of the lithium salt in the composite (CAM) may be 5 wt% to 50 wt%, 10 wt% to 50 wt%, 20 wt% to 50 wt%, or 30 wt% to 50 wt% of the total weight of the composite (CAM). By having the lithium salt content within this range, the composite (CAM) can simultaneously have improved ionic conductivity and excellent ductility.

[0080] The content of metal halide in the composite (CAM) may be 5 wt% to 30 wt% or 5 wt% to 20 wt% of the total weight of the composite (CAM). By having a metal halide content within this range, the composite (CAM) can simultaneously have improved ionic conductivity and excellent ductility.

[0081] In one embodiment, the content of Li2S in the composite (CAM) may be greater than the content of the lithium salt. The content of Li2S in the composite (CAM) may be greater than the content of the metal halide. For example, the molar ratio of Li2S to the lithium salt in the composite (CAM) may be 51:49 to 95:5, 55:45 to 90:10, 60:40 to 90:10, or 70:30 to 90:10. By having such molar ratios, the composite (CAM) can simultaneously possess enhanced ionic conductivity and excellent ductility.

[0082] The ionic conductivity of the composite (CAM) according to the embodiments of the present invention is, for example, 1×10⁻⁶ at 25°C. -5 S / cm or more, 2×10 -5 S / cm or more, 4×10 -5 S / cm or more, 6×10 -5 S / cm or more, 8×10 -5 S / cm or more or 1×10 -4 It may be greater than S / cm. For example, ionic conductivity can be measured using electrochemical impedance spectrometry, DC polarization method, etc. As the composite (CAM) has ionic conductivity in this range, the internal resistance of the positive active material layer (120) containing the composite (CAM) can be further reduced.

[0083] The average particle size (D50) of the composite (CAM) may be, for example, 2 μm or less, 1.5 μm or less, or 1 μm or less. The average particle size of the composite (CAM) may be, for example, 0.1 μm to 2 μm, 0.1 μm to 1.5 μm, or 0.1 μm to 1 μm.

[0084] The size of the Li2S particles in the composite (CAM) may be, for example, 2 μm or less, 1.5 μm or less, or 1 μm or less. The size of the Li2S particles may be, for example, 0.1 μm to 2 μm, 0.1 μm to 1.5 μm, or 0.1 μm to 1 μm.

[0085] Referring again to FIGS. 2 and FIG. 3, the positive active material layer (120) may further include a solid electrolyte (SEP) in addition to the Li2S-containing positive active material (CAC). The solid electrolyte (SEP) in the positive active material layer (120) may be the same as or different from the solid electrolyte in the solid electrolyte layer (300) to be described later.

[0086] The solid electrolyte (SEP) in the positive active material layer (120) may have an average particle size (D50) smaller than that of the solid electrolyte in the solid electrolyte layer (300). For example, the average particle size of the solid electrolyte (SEP) in the positive active material layer (120) may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the average particle size of the solid electrolyte in the solid electrolyte layer (300).

[0087] In one embodiment, the content of the positive active material (CAC) in the positive active material layer (120) may be 40 wt% to 90 wt%, 50 wt% to 90 wt%, or 60 wt% to 90 wt% of the total weight of the positive active material layer (120). Among the components in the positive active material layer (120), the positive active material (CAC) may have the largest content. The content of the solid electrolyte (SEP) in the positive active material layer (120) may be 10 wt% to 70 wt%, 10 wt% to 60 wt%, or 10 wt% to 40 wt% of the total weight of the positive active material layer (120).

[0088] The solid electrolyte (SEP) may be, for example, a sulfide-based solid electrolyte. Sulfide-based solid electrolytes are, 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, Z is one of Ge, Zn, or Ga, Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q , p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, In, Li 7-x PS 6-x Cl x , 0≤x≤2, Li 7-x PS 6-x Br x , 0≤x≤2, and Li 7-x PS 6-x I x, 0≤x≤2, and one or more selected from. Sulfide-based solid electrolytes are produced by processing starting materials, such as Li2S or P2S5, by methods such as melt quenching or mechanical milling. Additionally, heat treatment may be performed after such processing. The solid electrolyte may be amorphous, crystalline, or a mixture thereof. Furthermore, the solid electrolyte may include sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the sulfide-based solid electrolyte materials described above. For example, the solid electrolyte may be a material containing Li2S-P2S5. When using a sulfide-based solid electrolyte material comprising Li2S-P2S5 to form a solid electrolyte, the molar ratio of Li2S and P2S5 is, for example, in the range of Li2S : P2S5 = 20 : 80 to 90 : 10, 25 : 75 to 90 : 10, 30 : 70 to 70 : 30, and 40 : 60 to 60 : 40.

[0089] Sulfide-based solid electrolytes may include, for example, an argyrodite-type solid electrolyte represented by the following chemical formula 1:

[0090] <Chemical Formula 1>

[0091] Li + 12-n-x A n+ X 2- 6-x Y - x

[0092] In the above formula, A is P, As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb, or Ta; X is S, Se, or Te; Y is Cl, Br, I, F, CN, OCN, SCN, or N3; and 1≤n≤5, 0≤x≤2. Sulfide-based solid electrolytes are, for example, Li 7-x PS 6-x Cl x , 0≤x≤2, Li7-x PS 6-x Br x , 0≤x≤2, and Li 7-x PS 6-x I x It may be an argyrodite-type compound containing one or more selected from 0≤x≤2. The sulfide-based solid electrolyte may be an argyrodite-type compound containing, for example, one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0093] Alternatively, sulfide-based solid electrolytes are Li 7-a M a PS 6-c X c It may be an argyrodite-type compound containing (0≤a≤2, (0≤c≤2)). Here, X may be F, Br, Cl, or a combination thereof. M may be 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.

[0094] The density of the argyrodite-type solid electrolyte may be 1.5 to 2.0 g / cc. Since the argyrodite-type solid electrolyte has a density of 1.5 g / cc or higher, the internal resistance of the all-solid-state secondary battery is reduced, and penetration of the solid electrolyte layer by Li can be effectively suppressed.

[0095] The positive active material layer (120) may further include a filler (FIL). In one embodiment, the content of the filler (FIL) in the positive active material layer (120) may be 0.1 to 20 wt%, 0.1 to 10 wt%, or 0.1 to 5 wt% of the total weight of the positive active material layer (120).

[0096] The positive active material layer (120) may further include a conductive material. The conductive material may be, for example, a carbon-based material, a metal-based material, or a combination thereof. In one embodiment of the present invention, as shown in FIG. 3, the conductive material (CMA) in the positive active material layer (120) may form a positive active material (CAC) together with a composite (CAM).

[0097] The conductive material content in the positive active material layer (120) may be, for example, 1 wt% to 30 wt%, 1 wt% to 20 wt%, or 1 wt% to 10 wt% of the total weight of the positive active material layer (120).

[0098] Metallic materials may be metal powders, metal fibers, or combinations thereof, but are not limited to these; any metal-based material used as a conductive material in the relevant technical field is acceptable.

[0099] The carbon-based material may include, for example, amorphous carbon. By including amorphous carbon in the carbon-based material, side reactions between the carbon-based material and the solid electrolyte (SEP) can be suppressed. Accordingly, the cycle characteristics of the all-solid-state battery (10) containing the carbon-based material can be further improved. A specific description of the carbon-based material may be the same or similar as that described above regarding the conductive material (CMA).

[0100] The positive active material layer (120) may further include a binder (BID). The binder may be, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene (PTFE), polyvinylidene fluoride, polyethylene, etc., but is not limited to these and may be any binder used in the relevant technical field. The content of the binder (BID) in the positive active material layer (120) may be, for example, 0.1 wt% to 10 wt%, 0.5 to 5 wt%, or 0.5 to 2 wt% of the total weight of the positive active material layer (120). The binder (BID) may be omitted.

[0101] The positive active material layer (120) may further include additives such as a coating agent, a dispersant, and an ion conductivity aid in addition to the above-described positive active material (e.g., CAM), solid electrolyte (SEP), binder (BID), conductive material (CMA), and filler (FIL). Known materials generally used in electrodes of all-solid-state batteries may be used as coating agents, dispersants, and ion conductivity aids that may be included in the positive active material layer (120).

[0102] The negative electrode layer (200) may include a negative electrode current collector (210) and a negative electrode coating layer (220) on the negative electrode current collector (210). The negative electrode current collector (210) may provide a reference surface on which the negative electrode coating layer (220) is placed. The negative electrode current collector (210) may include, for example, a material that does not react with lithium, that is, does not form any alloys or compounds with lithium. For example, the negative electrode current collector (210) may include at least one metal selected from the group consisting of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The thickness of the negative electrode current collector (210) may be 1 μm to 20 μm, more specifically 5 μm to 15 μm, and more specifically 7 μm to 10 μm.

[0103] The negative current collector (210) may be composed of one of the metals described above, or may include an alloy of two or more metals or a coating material. The negative current collector (210) may, for example, have a plate-like or foil-like shape. Meanwhile, in one embodiment, the negative current collector (210) may be omitted.

[0104] Although not illustrated, a negative current collector (210) according to one embodiment may include a base film and a metal layer disposed on one or both sides of the base film. The base film may include, for example, a polymer. The polymer may be, for example, a thermoplastic polymer. The polymer may include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. The polymer may be an insulating polymer. By including an insulating thermoplastic polymer in the base film, the base film may soften or liquefy upon a short circuit, thereby blocking battery operation and suppressing a sudden increase in current. The metal layer may include, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), or an alloy thereof. The negative current collector (210) may additionally include a metal piece and / or a lead tab. For more specific details regarding the base film, metal layer, metal chip, and lead tab of the negative electrode current collector (210), refer to the positive electrode current collector (110) described above. By having the negative electrode current collector (210) have this structure, the weight of the negative electrode layer (200) can be reduced, and consequently, the energy density of the all-solid-state battery (10) can be improved.

[0105] The negative electrode coating layer (220) can be configured to allow lithium metal to grow between the all-solid-state battery (10) and the negative electrode current collector (210) 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.

[0106] The cathode coating layer (220) may include metal and carbon. For example, the cathode coating layer (220) may include at least one metal selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The cathode coating layer (220) may include at least one carbon selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene. In one embodiment, the cathode coating layer (220) may include a mixture of carbon black and silver (Ag).

[0107] The cathode coating layer (220) may further include other additives in addition to metal and carbon. 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.

[0108] 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 (10). If the thickness of the negative electrode coating layer (220) increases excessively, the energy density of the all-solid-state battery (10) decreases, and the internal resistance of the all-solid-state battery (10) due to the negative electrode coating layer (220) increases, which may degrade the cycle characteristics of the cell.

[0109] Meanwhile, although not shown, a carbon layer may be further included to improve adhesion between the cathode coating layer (220) and the solid electrolyte layer (300).

[0110] A solid electrolyte layer (300) may be provided between the positive electrode layer (100) and the 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 (SEP, see FIG. 3) in the aforementioned positive electrode active material layer (120).

[0111] The solid electrolyte layer (300) may include a first solid electrolyte layer (310) and a second solid electrolyte layer (320). The first solid electrolyte layer (310) may be adjacent to the anode layer (100), and the second solid electrolyte layer (320) may be adjacent to the cathode layer (200).

[0112] Referring to FIG. 2, the first solid electrolyte layer (310) may include a first solid electrolyte. The first solid electrolyte may have a particle shape such as a sphere or an ellipsoid. The first solid electrolyte may include a sulfide-based solid electrolyte. The first solid electrolyte may be amorphous, crystalline, or a mixture thereof. Additionally, the solid electrolyte may include sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the sulfide-based solid electrolyte materials described above, for example. For example, the solid electrolyte may be a material containing Li2S-P2S5. When using a sulfide-based solid electrolyte material containing Li2S-P2S5 to form the solid electrolyte, the molar ratio of Li2S and P2S5 may be, for example, in the range of Li2S : P2S5 = 50 : 50 to 90 : 10.

[0113] In one embodiment, the first solid electrolyte is Li 7-x PS6-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 an argyrodite-type compound comprising one or more selected from (0≤x≤2). The first solid electrolyte may include an argyrodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0114] In another embodiment, the first solid electrolyte is Li 7-a M a PS 6-c X c It may include an argyrodite-type compound comprising. Here, X may be Cl, Br, or a combination thereof. M may be Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn, or a combination thereof. a and c may each be a real number between 0 and 2.

[0115] The density of the azyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. Since the azyrodite-type solid electrolyte has a density of 1.5 g / cc or higher, the internal resistance of the all-solid-state battery is reduced, and defects such as penetration and short circuit of the solid electrolyte film due to lithium dendrite formation can be prevented. The elastic modulus of the first solid electrolyte is, for example, 15 GPa to 35 GPa.

[0116] The second solid electrolyte layer (320) may include a second solid electrolyte. The second solid electrolyte may have a particle shape such as a sphere or an ellipsoid. The second solid electrolyte may include a sulfide-based solid electrolyte. The description of the second solid electrolyte may be the same or similar as that described above for the first solid electrolyte. In one embodiment, the second solid electrolyte may have substantially the same composition as the first solid electrolyte. In another embodiment, the second solid electrolyte may have a composition similar to that of the first solid electrolyte.

[0117] The second solid electrolyte can come into direct contact with the negative electrode coating layer (220). By doing so, the second solid electrolyte can suppress lithium dendrites formed between the negative electrode coating layer (220) and the negative electrode current collector (210). The second solid electrolyte can effectively suppress negative side reactions. By doing so, the cell performance of the all-solid-state battery (10) according to the present invention can be improved.

[0118] Each of the first and second solid electrolyte layers (310, 320) may further include a binder. The binder in the solid electrolyte layer (300) is, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited to these. The binder in the solid electrolyte layer (300) may be the same as or different from the binder in the positive active material layer (120) or the binder in the negative coating layer (220).

[0119] The content of the binder in the solid electrolyte layer (300) may be 0.1 to 10 wt%, 0.1 to 5 wt%, 0.1 to 3 wt%, 0.1 to 1 wt%, 0 to 0.5 wt%, or 0 to 0.1 wt% with respect to the total weight of the solid electrolyte layer (300).

[0120] In another embodiment of the present invention, the solid electrolyte layer (300) may be provided as a single layer structure rather than a double layer structure of the first solid electrolyte layer (310) and the second solid electrolyte layer (320).

[0121] Referring again to FIGS. 1 and FIGS. 2, the anode layer (100) and the first solid electrolyte layer (310) can form an anode composite layer (CSH). The cathode layer (200) and the second solid electrolyte layer (320) can form a cathode composite layer (ASH). An anode composite layer (CSH) can be laminated on the cathode composite layer (ASH).

[0122] The area of ​​the cathode composite layer (ASH) and the area of ​​the anode composite layer (CSH) may differ from each other. Specifically, the area of ​​the cathode composite layer (ASH) may be larger than the area of ​​the anode composite layer (CSH). The anode composite layer (CSH) may completely overlap within the cathode composite layer (ASH).

[0123] In one embodiment of the present invention, the first solid electrolyte layer (310) may have substantially the same area as the anode layer (100). The second solid electrolyte layer (320) may have substantially the same area as the cathode layer (200).

[0124] Specifically, the positive electrode composite layer (CSH) may have a first width (WI1) in a first direction (D1). The negative electrode composite layer (ASH) may have a second width (WI2) in a first direction (D1). The first width (WI1) may be smaller than the second width (WI2). The positive electrode composite layer (CSH) may have a third width (WI3) in a second direction (D2). The negative electrode composite layer (ASH) may have a fourth width (WI4) in a second direction (D2). The third width (WI3) may be smaller than the fourth width (WI4).

[0125] The all-solid-state battery (10) according to the present embodiment can be manufactured by forming a negative electrode composite layer (ASH) on a first carrier film and forming a positive electrode composite layer (CSH) on a second carrier film, and then laminating the negative electrode composite layer (ASH) and the positive electrode composite layer (CSH).

[0126]

[0127] In the embodiments described below, detailed descriptions of technical features that overlap with those previously described with reference to FIGS. 1 to 3 are omitted, and differences are described in detail.

[0128] The all-solid-state battery according to the present invention may include an adsorption layer (ADL). In the case of an all-solid-state battery containing a sulfide-based solid electrolyte, hydrogen sulfide (H2S) gas, which is a toxic gas, is inevitably generated when the battery is damaged; the adsorption layer (ADL) can improve the stability of the battery by absorbing hydrogen sulfide gas.

[0129] FIG. 2 is a cross-sectional view along line A-A' of FIG. 1 of an all-solid-state battery unit cell according to one embodiment. Referring to FIG. 2, the all-solid-state battery (10) may include an adsorption layer (ADL) formed on at least one of a positive current collector and a negative current collector, and the adsorption layer may be configured to adsorb hydrogen sulfide. The adsorption layer may include at least one of a first adsorption layer provided on the outer surface of the positive current collector and a second adsorption layer provided on the outer surface of the negative current collector. At least one of the positive current collector and the negative current collector may have at least one hole (HL) configured to allow hydrogen sulfide to be discharged. The hole (HL) may facilitate hydrogen sulfide passing through the adsorption layer (ADL).

[0130] In one embodiment of the present invention, when viewed in a planar view, the ratio of the area of ​​the positive current collector (110) to the area occupied by the opening of the hole (HL) may be 65:35 to 97:3, preferably 78:22 to 92:8, more preferably 82:28 to 88:12. The ratio of the area of ​​the negative current collector (210) to the area occupied by the opening of the hole (HL) may be 65:35 to 97:3, preferably 78:22 to 92:8, more preferably 82:28 to 88:12.

[0131] If the area of ​​the opening of the hole (HL) becomes excessively small, there is a concern that the resistance to the movement of lithium delivered to each electrode may increase and the rate of pre-lithiation may decrease. On the other hand, if the area of ​​the opening of the hole (HL) becomes excessively large, as the opening increases, the tensile strength of the current collector decreases, the current collector may fail to perform its function, and there is a concern that the performance of the battery may be degraded.

[0132] The diameter of the opening of the hole (HL) may be 30㎛ to 150㎛, preferably 50㎛ to 130㎛. When the diameter is within this range, an increase in lithium mobility resistance can be prevented, and the risk of failure due to wire breakage can be eliminated. Cost reduction for drilling may also be possible by appropriately adjusting the diameter of the opening. The hole (HL) may be formed in a cylindrical shape, a square prism shape, a triangular prism shape, etc., and specifically, it may be formed in a square prism shape.

[0133] In one embodiment, in the case of an all-solid-state battery having a unit cell structure (see FIG. 2), an adsorption layer (ADL) may be formed on a positive current collector (110) and a negative current collector (210). Although not illustrated, in the case of a unit cell structure, an adsorption layer (ADL) may be formed on only one of the positive current collector (110) and the negative current collector (210).

[0134] FIG. 4 is a cross-sectional view of an all-solid-state battery unit cell after a cycle according to one embodiment. Referring to FIG. 4, the adsorption layer (ADL) can absorb hydrogen sulfide as the cycle proceeds and can expand in volume. This prevents short circuits in the electrode layer within the all-solid-state battery cell according to the present invention and improves the reduction of internal pressure. In addition, the interface between the positive electrode layer (100) and the solid electrolyte layer (300) and the interface between the solid electrolyte layer (300) and the negative electrode layer (200) can be closely bonded. Therefore, the all-solid-state battery according to the present invention can have improved bonding strength and can achieve long lifespan and high rate characteristics.

[0135] FIG. 5 is a cross-sectional view of an all-solid-state battery unit cell according to another embodiment. Referring to FIG. 5, the at least one hole (HL) may include a first hole (HL1) provided in an edge region of the positive current collector and a second hole (HL2) provided in a central region of the positive current collector. The first hole (HL1) may include a plurality of first holes (HL1), and the second hole (HL2) may include a plurality of second holes (HL2). The density of the plurality of first holes (HL1) may be greater than the density of the plurality of second holes (HL2).

[0136] In this specification, “hole density” refers to the density of holes, which may mean the number of holes present per unit area. Hole density can be measured by methods widely known to those skilled in the art, for example, by measuring with a transmission electron microscope (TEM) image or a scanning electron microscope (SEM) image, or by measuring with a particle size analyzer. When measuring with a transmission electron microscope, more specifically, the hole density can be derived by acquiring an image by applying a voltage of 5 to 30 kV at a resolution of 1 to 10 nm and a magnification of 1,000 to 100,000 times, and then calculating the number of holes present per unit area using analysis software (e.g., ImageJ and / or MATLAB). Another method involves measuring with a scanning electron microscope (SEM), more specifically, by acquiring an image with a resolution of 0.1 to 0.5 nm and a magnification of 10,000 to 1,000,000 times and applying a voltage of 80 to 300 kV, and then using analysis software (e.g., ImageJ and / or MATLAB) to calculate the number of holes per unit area to derive the hole density.

[0137] Additionally, the above-mentioned at least one hole (HL) may include a third hole (HL3) provided in the edge region of the negative current collector and a fourth hole (HL4) provided in the central region of the negative current collector. The third hole (HL3) may include a plurality of third holes (HL3), and the fourth hole (HL4) may include a plurality of fourth holes (HL4). The density of the plurality of third holes (HL3) may be greater than the density of the plurality of fourth holes (HL4).

[0138] FIG. 6 is a cross-sectional view of an all-solid-state battery bi-cell according to one embodiment. Referring to FIG. 6, the all-solid-state battery (10) may have a bi-cell structure. The bi-cell structure may be a structure in which a solid electrolyte layer (SEL) and a second electrode (ETD2) are symmetrically arranged facing each other with respect to a first electrode (ETD1). In one embodiment, the all-solid-state battery with a bi-cell structure may have a form in which a first negative electrode, a first solid electrolyte layer, a positive electrode, a second solid electrolyte layer, and a second negative electrode are sequentially stacked. In another embodiment, the all-solid-state battery with a bi-cell structure may have a form in which a first positive electrode, a first solid electrolyte layer, a negative electrode, a second solid electrolyte layer, and a second positive electrode are sequentially stacked. In the case of an all-solid-state battery having a bi-cell structure (see FIG. 6), an adsorption layer (ADL) may be formed only on the second electrode current collector (PLT2). The adsorption layer (ADL) may be formed on only one of the two second electrode current collectors (PLT2), or it may be formed on both second electrode current collectors (PLT2).

[0139] In this specification, the term "unit cell" may refer to a basic unit comprising components that constitute a cell. For example, a unit cell may include a first electrode, a second electrode having opposite polarity to the first electrode, and a solid electrolyte layer between the first and second electrodes. The first electrode may include a first electrode current collector (PLT1) and a first electrode coating layer and / or a first electrode active material layer formed on the first electrode current collector (PLT1), and the second electrode may include a second electrode current collector (PLT2) and a second electrode coating layer and / or a second electrode active material layer formed on the second electrode current collector (PLT2). In one embodiment, the unit cell may include an anode, a cathode, and a solid electrolyte layer between the anode and the cathode. The solid electrolyte layer included in the unit cell may particularly include a sulfide-based solid electrolyte.

[0140] The all-solid-state battery according to the present invention is not particularly limited in the shape of the housing, and the housing can be implemented in various forms such as pouch type, can type, cylindrical type, and prismatic type, but is not limited thereto. For example, the all-solid-state battery according to the present invention may be a pouch-type all-solid-state battery.

[0141] In one embodiment, for a pouch-type all-solid-state battery, the adsorption layer (ADL) may include a pouch layer. The adsorption layer (ADL) may be formed as part of the pouch layer, applied to the pouch layer, implemented in the form of a pouch, or formed in a structure that is laminated or coated on the pouch layer. Additionally, the adsorption layer (ADL) may be implemented in a form where the pouch layer itself performs the adsorption function, and furthermore, the adsorption layer (ADL) may be a structure integrated with the outer or inner shell of the pouch layer.

[0142] Specifically, the adsorption layer (ADL) is a pouch layer, and the pouch layer may be an independent layer disposed to be in direct contact with or adjacent to at least one of the positive current collector and the negative current collector. In this case, the adsorption layer (ADL) may be physically separated from the pouch layer as a separate layer, or may be formed integrally with the pouch layer. The adsorption layer (ADL) may be a structure coated or laminated on the inner or outer side of the pouch film. The adsorption layer (ADL) can adsorb hydrogen sulfide and may be configured to expand in volume when adsorbing hydrogen sulfide.

[0143] FIG. 7 is a cross-sectional view of a pouch-type all-solid-state battery according to another embodiment. Referring to FIG. 7, the pouch-type all-solid-state battery may be a solid-state battery (10) that can be packaged in a pouch (PCH). More specifically, the pouch-type all-solid-state battery may have an electrode assembly in which at least one unit cell is stacked and packaged in a pouch (PCH). In the case of the pouch-type all-solid-state battery, an adsorption layer (ADL) may be formed on the pouch (PCH). The adsorption layer (ADL) may be configured to adsorb hydrogen sulfide. Additionally, the adsorption layer (ADL) may be configured to expand in volume when adsorbing hydrogen sulfide. Below, a pouch-type all-solid-state battery including an adsorption layer (ADL) will be described in more detail.

[0144] The pouch (PCH) can package an electrode assembly in which the unit cells are stacked, thereby protecting and isolating the electrode assembly from the outside. An all-solid-state battery packaged in a pouch (PCH) can be used as a single independent unit battery. Multiple pouch-type all-solid-state batteries can be combined to form a battery module. Multiple battery modules can be combined to form a battery pack. Pouch-type batteries have a relatively simple structure and can reduce volume and weight. In addition, they are flexible and can be manufactured in various shapes.

[0145] Referring to FIG. 7, the pouch (PCH) may comprise an adsorption layer (ADL), an insulating layer (ISL) formed on at least one surface of the adsorption layer, and a metal layer (MFL) on the insulating layer (ISL). In one embodiment, the pouch (PCH) may comprise an adsorption layer (ADL), a metal layer (MFL), and a pair of insulating layers (ISL) sandwiching the metal layer (MFL).

[0146] In one embodiment, the adsorption layer (ADL) may be formed on only one side of the metal layer (MFL).

[0147] Referring again to FIG. 7, the adsorption layer (ADL) of the pouch (PCH) may be formed to be in direct contact with or adjacent to the current collector (PLT2). When hydrogen sulfide is discharged through the hole (HL) of the current collector (PLT2), the adsorption layer (ADL) directly adjacent to the current collector (PLT2) can easily adsorb the hydrogen sulfide. The metal layer (MFL) may include a metal that maintains mechanical strength while having flexibility. For example, the metal layer (MFL) may include aluminum (Al). In addition to aluminum, the metal layer (MFL) may include one or more metals selected from the group consisting of iron (Fe), carbon (C), chromium (Cr), manganese (Mn), and nickel (Ni). Aluminum (Al) may be included in an amount of 90% to 99.9% by weight relative to the total mass of the metal layer (MFL). The thickness of the metal layer (MFL) may be 20 μm to 50 μm, or 30 μm to 40 μm.

[0148] The insulating layer (ISL) may include an insulating material. For example, the insulating layer (ISL) may have a single-layer structure made of any one material selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber, or a composite-layer structure made of two or more materials. By including the insulating layer (ISL) in the pouch (PCH), the metal layer (MFL) can be prevented from being damaged by friction, impact, etc. from the outside. In addition, the insulating layer (ISL) can prevent the metal layer (MFL) from coming into direct contact with the electrode assembly. The thickness of the insulating layer (ISL) may be 10 μm to 50 μm.

[0149] The insulating layer (ISL) may include a polymer having a melting point of about 170°C or less. For example, the melting point of the polymer included in the insulating layer (ISL) may be 140°C to 160°C. The melting point of the insulating layer (ISL) may be about 170°C or less. The melting point of the insulating layer (ISL) may be, for example, 140°C to 170°C, 140°C to 160°C, or 150°C to 160°C.

[0150] As described above, the adsorption layer (ADL) can adsorb hydrogen sulfide and can be configured to expand in volume when adsorbing hydrogen sulfide. The adsorption layer (ADL) can be located inside a pouch and can be located on at least one of a positive current collector and a negative current collector. The holes (HL) in the current collectors can allow hydrogen sulfide gas generated by electrochemical side reactions at the interface between the positive layer (100) and the solid electrolyte layer (300) and / or the interface between the solid electrolyte layer (300) and the negative layer (200) to pass through during charging and discharging of the cell. The passed hydrogen sulfide can be absorbed through the adsorption layer (ADL), thereby causing the volume of the adsorption layer (ADL) to expand. The volume-expanded adsorption layer (ADL) can compensate for the internal pressure drop problem of the lithium-sulfur battery and reduce the increase in inter-particle network interface resistance caused by the reduction in active material size.

[0151] FIG. 8 is a cross-sectional view of an all-solid-state battery unit cell after a cycle according to a comparative example. Referring to FIG. 8, if the adsorption layer (ADL) according to the present invention is omitted, hydrogen sulfide gas is generated as an electrochemical side reaction occurs at the interface between the anode layer (100) and the solid electrolyte layer (300) and / or the interface between the solid electrolyte layer (300) and the cathode layer (200) as the cycle progresses, and interfacial delamination may occur due to non-uniform volume expansion. Accordingly, interfacial resistance may increase, the internal pressure of the cell may drop, and lifespan characteristics may deteriorate. In the case of an all-solid-state battery including the adsorption layer (ADL) according to the present invention (see FIG. 4), hydrogen sulfide may be absorbed as the cycle progresses and the volume may expand. Referring to FIGS. 4 and 8, when comparing an all-solid-state battery having an adsorption layer (ADL) with an all-solid-state battery without an adsorption layer (ADL), in the case of an all-solid-state battery having an adsorption layer (ADL), the bonding strength between the interface of the positive electrode layer (100) and the solid electrolyte layer (300) and / or the interface between the solid electrolyte layer (300) and the negative electrode layer (200) can be excellent. This prevents short circuits in the electrode layers within the all-solid-state battery cell according to the present invention, improves internal pressure reduction, and enables long lifespan and high rate characteristics.

[0152] FIG. 9 is a flowchart illustrating a method for manufacturing an all-solid-state battery according to embodiments of the present invention. Referring to FIG. 9, the method for manufacturing an all-solid-state battery may include the steps of: forming a positive electrode and a negative electrode (S100); forming a hole in one of the current collectors (S200); forming a cell stack (S300); and forming an adsorption layer (S400).

[0153] The step of forming an anode and a cathode (S100) may include the step of forming an anode including an anode current collector and an anode active material layer; and the step of forming a cathode including a cathode current collector and a cathode coating layer.

[0154] Specifically, the method may include the steps of: providing Li2S or a composite thereof; providing a sulfide-based solid electrolyte; preparing a mixture by mixing the Li2S composite, the gamma-sulfur-carbon nanofiber composite, and the sulfide-based solid electrolyte; and preparing to manufacture a cathode by coating and drying the mixture onto a cathode current collector. The Li2S composite may be a composite of Li2S and a lithium salt or a composite of Li2S, a lithium salt, and a carbon-based material. The composite of Li2S and a lithium salt may be prepared, for example, by mechanically milling Li2S and a lithium salt. The milling conditions are not particularly limited and any conditions capable of forming a composite of Li2S and a lithium salt are possible. A composite of Li2S and a lithium salt may be prepared by feeding Li2S particles and a lithium salt into a ball mill and stirring at a speed of 100 to 1000 rpm for 1 to 20 hours. Stirring may be performed one or more times. As a lithium salt, for example, LiI, LiBr, LiCl, LiF, LiH, Li2O, Li2Se, Li2Te, Li3N, Li3P, Li3As, Li3Sb, Li3Al2, LiB3, Li3OCl, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiNO3, Li2CO3, LiBH4, Li2SO4, Li3BO3, Li3PO4, Li4NCl, Li5NCl2, Li3BN2, or a combination thereof may be used. A composite of Li2S, a lithium salt, and a carbon-based material may be manufactured, for example, by mechanically milling Li2S and a lithium salt; adding a carbon-based material to the milled product and milling it.

[0155] A sulfide-based solid electrolyte is provided. A mixture is prepared by mixing a Li2S-lithium salt complex with the sulfide-based solid electrolyte. The mixing ratio of the Li2S complex and the sulfide-based solid electrolyte may be, for example, a weight ratio of 50:50 to 95:5, 50:50 to 90:10, 50:50 to 80:20, or 50:50 to 70:30. The mixture may additionally contain a process solvent. By additionally containing a process solvent, the mixture may have a slurry form. The solvent may be, for example, octyl acetate, but is not limited thereto; any solvent used in the art is acceptable. Alternatively, the mixture may be prepared dry without containing a process solvent. Mechanical milling may be used for the milling process. A ball mill or the like may be used for mechanical milling.

[0156] The step of forming a hole in one of the current collectors (S200) may include the step of forming a hole (HL) in the current collector to facilitate the passage of hydrogen sulfide through the adsorption layer (ADL). Specifically, a hole (HL) may be manufactured such that the ratio of the surface area of ​​the positive current collector (110) and the negative current collector (210) to the area occupied by the opening of the hole (HL) is 65:35 to 97:3, preferably 78:22 to 92:8, and more preferably 82:28 to 88:12. A hole (HL) may be manufactured such that the diameter of the opening of the hole (HL) is 30㎛ to 150㎛, preferably 50㎛ to 130㎛. The hole (HL) may be manufactured in a cylindrical shape, a square prism shape, a triangular prism shape, etc., and specifically, it may be manufactured in a square prism shape.

[0157] The step of forming a cell stack (S300) may include the step of obtaining a battery assembly and pressing it after the step of placing a solid electrolyte layer between the anode and the cathode. Pressing may be performed using, for example, a roll press or a flat press, but is not necessarily limited to these methods and any press used in the relevant technical field is possible. The press step may be omitted. Pressing is performed at a temperature of, for example, room temperature (20°C to 25°C) to 90°C. Alternatively, pressurizing may be performed at a high temperature of 100°C or higher. The time for applying pressurization may be, for example, 30 minutes or less, 20 minutes or less, 15 minutes or less, or 10 minutes or less. The time for applying pressurization may be 1 ms to 30 minutes, 1 ms to 20 minutes, 1 ms to 15 minutes, or 1 ms to 10 minutes. The pressurization method may be, for example, isotactic press, roll press, flat press, etc., but is not necessarily limited to these methods; any pressurization method used in the relevant technical field is acceptable. The pressure applied during pressurization may be, for example, 500 MPa or less, for example, 400 MPa or less, 300 MPa or less, 200 MPa or less, or 100 MPa or less. The pressure applied during pressurization may be, for example, 50 MPa to 500 MPa, 50 MPa to 400 MPa, 50 MPa to 300 MPa, 50 MPa to 200 MPa, 50 MPa to 100 MPa. Through such pressurization, for example, solid electrolyte powder may be sintered to form a single solid electrolyte. The pressurization step may be, for example, 40 to 100°C, for example, 85 oPlate press treatment can be performed at a pressure of 500 MPa for 30 minutes. Through this press treatment, the solid electrolyte layer is sintered, and battery characteristics can be improved. According to another embodiment, the above-described press treatment process may be omitted.

[0158] The step of forming an adsorption layer (S400) may consist of: preparing a material for forming the adsorption layer; forming an adsorption layer on a temporary support; and attaching a current collector. The adsorption layer may be manufactured to adsorb hydrogen sulfide. As the material for forming the adsorption layer, metal oxides (e.g., ZnO, Fe₂O₃), activated carbon, or metal-organic frameworks (MOFs) may be used, but are not necessarily limited to these materials; any material used in the relevant technical field is acceptable. As the temporary support, glass, plastic, or ceramic may be used, but is not necessarily limited to these materials, and a uniform adsorption layer can be formed by a coating method. The adsorption layer may be manufactured to include at least one of a first adsorption layer provided on the outer surface of the positive current collector and a second adsorption layer provided on the outer surface of the negative current collector. The adsorption layer may be formed with a thickness of about 10 μm to 40 μm.

[0159]

[0160] The embodiments of the present invention will be described in more detail below. However, the following embodiments are provided merely to aid in understanding the present invention and do not limit the scope of the present invention.

[0161]

[0162] Example 1

[0163] (Manufacture of porous current collectors)

[0164] Aluminum (Al) was prepared as the anode current collector material. An aluminum sheet was immersed in a sulfuric acid (H₂SO₄) solution at approximately 15°C, which served as the electrolyte. A constant voltage of approximately 25V was applied to form an Al₂O₃ layer, after which nano-holes of approximately 100 nm were formed penetrating the anode current collector. After oxidation was completed, the sheet was washed with water and heat-treated at approximately 200°C to stabilize the structure.

[0165] A SUS foil with a thickness of 10 μm was prepared as the cathode current collector material. The SUS foil was immersed in a sulfuric acid (H₂SO₄) solution at approximately 15°C. A constant voltage of approximately 25 V was applied for about 30 minutes to induce an oxidation reaction in which the metal is converted into ions. After washing, the foil was completely dried under nitrogen gas to form nano-holes of approximately 100 nm penetrating the cathode current collector.

[0166] (Anode manufacturing)

[0167] The porous aluminum current collector was prepared as the positive current collector. A Li2S-LiI-CNF composite was prepared as the positive active material. PVDF-HFP was prepared as the binder. These materials were mixed in a weight ratio of positive active material:Li6PS5Cl solid electrolyte (SE):binder = 60:39:1.0 to prepare a composition for forming a positive active material layer. The composition for forming the positive active material layer was milled, then dry-coated onto one side of the positive current collector, and the positive was manufactured by applying pressure at 1 MPa and 170°C for 10 minutes. The thickness of the positive was approximately 120 μm, and the loading level of the positive composite was approximately 8 mg / cm². The thickness of the positive active material layer was approximately 100 μm, and the thickness of the carbon-coated aluminum foil was approximately 20 μm. The surface area of ​​the positive active material layer and the positive current collector were the same.

[0168] (Cathode manufacturing)

[0169] The porous SUS current collector was prepared as the cathode current collector. As the cathode active material, 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. 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 adding NMP little by little to the prepared mixed solution. The prepared slurry was applied to the cathode current collector 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. A prepared laminate was cold-roll-pressed to flatten its surface, thereby preparing a cathode having a first cathode active material layer / cathode current collector structure. The thickness of the first cathode active material layer was approximately 15 μm. The area of ​​the first cathode active material layer and the cathode current collector were the same.

[0170] (Preparation of solid electrolyte layer)

[0171] Li6PS5Cl solid electrolyte, an argyrodite-type crystal (D 50 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 (=3.0 μm, crystalline). 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.

[0172] (Manufacturing of adsorption layer)

[0173] ZnO, a metal oxide, was used as the material for hydrogen sulfide adsorption. PVDF was used as a binder to immobilize the adsorbent, and NMP was used as a solvent to homogenize the mixture. An adsorption layer slurry was prepared by adding carbon, a conductive additive, to ensure conductivity. Glass was used as a temporary support to form the adsorption layer on the temporary support, and then approximately 200 o The strength of the adsorption layer was enhanced by heat treatment under C.

[0174] (Manufacturing of all-solid-state secondary batteries)

[0175] A cathode was placed on an adsorption layer, a solid electrolyte layer on the cathode, an anode on the solid electrolyte layer, and an adsorption layer on the anode. A laminate was prepared by placing a gasket around the anode, surrounding it and in contact with the solid electrolyte layer. The thickness of the gasket was approximately 120 μm. An inert polymer material with excellent flame retardancy was used as the gasket. The gasket was positioned to contact the side of the anode and the solid electrolyte layer. The anode was placed in the center of the solid electrolyte layer, and the gasket surrounded the anode and extended to the end of the solid electrolyte layer. The area of ​​the anode was approximately 90% of the solid electrolyte layer area, and the gasket was placed over the entire remaining 10% of the solid electrolyte layer area where the anode was not placed. The prepared laminate was 85 o Plate press treatment was performed at a pressure of 500 MPa for 30 minutes. This pressurization 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 negative electrode. An all-solid-state secondary battery was manufactured by placing the pressurized laminate into a pouch and vacuum sealing it. Parts of the positive and negative current collectors were extended outside the sealed battery to be used as the positive and negative terminals.

[0176]

[0177] Comparative Example 1

[0178] Holes were not formed in the positive current collector and the negative current collector, respectively, and the adsorption layer was also omitted. Except for this, an all-solid-state secondary battery was manufactured in the same manner as in Example 1.

[0179]

[0180] Evaluation Example 1: Evaluation of Lifespan Characteristics of All-Solid State Secondary Batteries

[0181] The life characteristics of the all-solid-state secondary battery prepared according to Example 1 and Comparative Example 1 were evaluated. The charge-discharge test was performed by placing the all-solid-state secondary battery in a chamber at 45°C.

[0182] The battery was charged with a constant current of 0.33C until the battery voltage reached 4.25V, and then charged at a constant voltage of 4.25V until the current value reached 0.1C. Subsequently, the battery was discharged with a constant current of 0.33C until the battery voltage reached 2.5V. This charge-discharge cycle was performed 100 times. A 10-minute rest period was taken after each charge and discharge step in each cycle.

[0183] The capacity retention rate of each all-solid-state secondary battery was measured. The capacity retention rate was calculated using Equation 1 below.

[0184] <Equation 1>

[0185] Capacity Retention Rate (%) = [Discharge Capacity of the 100th Cycle / Discharge Capacity of the 1st Cycle] × 100

[0186] Dose Retention Rate (%) Example 189 Comparative Example 156

[0187] Referring to Table 1, it can be seen that the capacity retention rate of the all-solid-state secondary battery of Example 1 is significantly improved compared to that of the all-solid-state secondary battery of Comparative Example 1. Through this, it can be seen that when an adsorption layer is present as in Example 1, hydrogen sulfide is absorbed into the adsorption layer, causing the volume of the adsorption layer to expand; consequently, the internal pressure of the cell does not decrease and interfacial desorption does not occur, thereby improving lifespan characteristics. On the other hand, in the case of Comparative Example 1, where an adsorption layer is absent, it can be seen that lifespan characteristics are significantly degraded due to interfacial desorption and cell short circuits.

[0188]

[0189] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto and can be implemented with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that such modifications also fall within the scope of the present invention.

Claims

1. A positive electrode comprising a positive current collector and a positive active material layer; A cathode comprising a cathode current collector and a cathode coating layer; A solid electrolyte layer disposed between the anode and the cathode; and The adsorption layer on at least one of the anode current collector and the cathode current collector, wherein The above positive active material layer includes a sulfide-based positive active material, and At least one of the above positive current collector and the above negative current collector has at least one hole configured to allow hydrogen sulfide to be discharged, and The above adsorption layer is configured to adsorb hydrogen sulfide, All-solid-state battery.

2. In Paragraph 1, The above adsorption layer is configured to expand in volume when adsorbing the hydrogen sulfide, All-solid-state battery.

3. In Paragraph 1, The above solid electrolyte layer comprises a sulfide-based solid electrolyte, All-solid-state battery.

4. In Paragraph 1, The above positive active material layer further comprises a sulfide-based solid electrolyte, All-solid-state battery.

5. In Paragraph 1, The above adsorption layer comprises a first adsorption layer provided on the outer surface of the anode current collector. All-solid-state battery.

6. In Paragraph 1, The above adsorption layer comprises a second adsorption layer provided on the outer surface of the cathode current collector. All-solid-state battery.

7. In Paragraph 1, The above at least one hole is: A first hole provided in the edge region of the anode current collector; and including a second hole provided in the central region of the anode current collector, All-solid-state battery.

8. In Paragraph 7, The above-mentioned first hole includes a plurality of first holes, and The above second hole includes a plurality of second holes, and The density of the plurality of first holes is greater than the density of the plurality of second holes, All-solid-state battery.

9. In Paragraph 1, The above at least one hole is: A third hole provided in the edge region of the above-mentioned cathode current collector; and including a fourth hole provided in the central region of the above-mentioned negative current collector, All-solid-state battery.

10. In Paragraph 9, The above third hole includes a plurality of third holes, and The above-mentioned fourth hole includes a plurality of fourth holes, and The density of the plurality of third holes is greater than the density of the plurality of fourth holes, All-solid-state battery.

11. Forming a positive electrode comprising a positive electrode current collector and a positive electrode active material layer; Forming a cathode comprising a cathode current collector and a cathode coating layer; Forming at least one hole configured to allow hydrogen sulfide to be discharged in at least one of the positive current collector and the negative current collector; Forming a cell stack by placing a solid electrolyte layer between the anode and the cathode; and The method comprises forming an adsorption layer on at least one of the positive current collector and the negative current collector of the cell stack, wherein The above adsorption layer is configured to adsorb hydrogen sulfide, Method for manufacturing an all-solid-state battery.

12. In Paragraph 11, The above solid electrolyte layer comprises a sulfide-based solid electrolyte, Method for manufacturing an all-solid-state battery.

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