Sulfide-based solid electrolyte and all-solid-state battery comprising same

Abstract

The present invention relates to a sulfide-based solid electrolyte, comprising a compound having an argyrodite-type crystal structure and represented by chemical formula 1: <Chemical formula 1> Li7-a-cMaPS6-b-cObXC (wherein the description of the chemical formula is as in the specification)

Description

Sulfide-based solid electrolyte and all-solid-state battery containing the same

[0001] It's about solid electrolytes.

[0002] All-solid-state secondary batteries contain solid electrolytes. Because they do not contain flammable organic solvents, they are highly safe.

[0003] All-solid-state secondary batteries, for example, contain sulfide-based solid electrolytes. After synthesis, sulfide-based solid electrolytes are crushed into a certain size for use.

[0004] One aspect is to provide a sulfide-based solid electrolyte composition with excellent softness.

[0005] Another aspect is to provide a sulfide-based solid electrolyte composition with improved thermal stability at high temperatures.

[0006] Another aspect is to provide an all-solid-state battery comprising the above sulfide-based solid electrolyte.

[0007] One embodiment provides a sulfide-based solid electrolyte having an argyrodite-type crystal structure and including a compound represented by the following chemical formula 1.

[0008] <Chemical Formula 1>

[0009] Li 7-a-c M a PS 6-b-c O b X C

[0010] In the above chemical formula 1,

[0011] The above M includes Na, K, Ca, Mg, Ag, Cu, Hf, In, Ti, Pb, Sb, Fe, Zn, Cr, B, Sn, Ge, Si, Zr, Ta, Nb, V, Ga, Al, As, or a combination thereof,

[0012] wherein X comprises Cl, Br, I, or a combination thereof,

[0013] 0 <a≤1, 0<b≤1, 및 1.5<c≤2 이다.

[0014] Another embodiment provides an all-solid-state battery comprising: a positive electrode layer including a positive electrode active material layer; a negative electrode layer; and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer; and at least one of the positive electrode active material layer and the solid electrolyte layer includes the above-described sulfide-based solid electrolyte.

[0015] According to one aspect, an all-solid-state battery having improved stability at high temperatures is provided by including a sulfide-based solid electrolyte having high thermal stability, good formability, and improved ionic conductivity.

[0016] Figure 1 is a DSC thermogram for the sulfide-based solid electrolytes manufactured in Examples 1 and 2 and Comparative Examples 1 and 2.

[0017] Figure 2 shows the XRD analysis results for the sulfide-based solid electrolytes manufactured in Examples 1 and 2 and Comparative Examples 1 and 2.

[0018] Figures 3 to 9 are schematic diagrams of one embodiment of an all-solid-state battery.

[0019] Figure 10 is a perspective view of an embodiment of an all-solid-state battery.

[0020] Various embodiments are illustrated in the accompanying drawings. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Like reference numerals in the drawings indicate like elements.

[0021] When a component is referred to as being "on" another component, it can be understood that it is either directly on top of the other component or that other components may be intervening between them. Conversely, when a component is referred to as being "directly on" another component, no intervening components are present.

[0022] Although the terms "first," "second," "third," etc. may be used herein to describe various components, elements, regions, layers, and / or zones, these components, elements, regions, layers, and / or zones should not be limited by these terms. These terms are used only to distinguish one component, element, region, layer, or zone from another component, element, region, layer, or zone. Thus, a first component, element, region, layer, or zone described below may be referred to as a second component, element, region, layer, or zone without departing from the teachings of this specification.

[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms including "at least one," unless the content clearly dictates otherwise. "At least one" should not be construed as limiting to the singular. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items. The terms "comprises" and / or "comprising" as used in the detailed description specify the presence of stated features, regions, integers, steps, operations, components, and / or ingredients, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, components, ingredients, and / or groups thereof.

[0024] Spatially relative terms such as "below," "under," "bottom," "above," "above," and "top" may be used herein to readily describe the relationship of one component or feature to another. It will be understood that spatially relative terms are intended to encompass different orientations of the device when in use or operation in addition to the orientations depicted in the drawings. For example, if the device in the drawings were turned over, a component described as "below" or "below" another component or feature would then be oriented "above" the other component or feature. Thus, the exemplary term "below" can encompass both the above and below orientations. The device can be arranged in other orientations (rotated 90 degrees or otherwise rotated), and the spatially relative terms used herein can be interpreted accordingly.

[0025] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Furthermore, it will be understood that terms defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning within the context of the relevant art and the present disclosure, and not in an idealized or overly formal sense.

[0026] Exemplary embodiments are described herein with reference to cross-sectional drawings that are schematic representations of idealized embodiments. As such, variations from the shapes depicted are to be expected, for example, as a result of manufacturing techniques and / or tolerances. Therefore, the embodiments described herein should not be construed as limited to the specific shapes of regions as depicted herein, but should encompass variations in shapes resulting from, for example, manufacturing. For example, regions depicted or described as flat may typically have rough and / or non-linear features. Moreover, angles depicted as sharp may be rounded. Therefore, the regions depicted in the drawings are schematic in nature, and their shapes are not intended to depict the precise shapes of the regions, nor are they intended to limit the scope of the claims.

[0027] "Group" means a group in the periodic table of elements according to the International Union of Pure and Applied Chemistry ("IUPAC") Group 1-18 classification system.

[0028] In this specification, “particle size” refers to the average diameter of spherical particles, and the average major axis length of non-spherical particles. Particle size can be measured using a particle size analyzer (PSA). “Particle size” refers to the average particle size, for example. “Average particle size” refers to the median particle diameter, D50, for example.

[0029] D50 is the size of the particle corresponding to 50% of the cumulative volume, calculated from the particle side with a smaller particle size in the particle size distribution measured by laser diffraction.

[0030] D90 is the size of the particle corresponding to 90% of the cumulative volume, calculated from the particle side with a smaller particle size in the particle size distribution measured by laser diffraction.

[0031] D10 is the size of the particle corresponding to 10% of the cumulative volume, calculated from the particle side with a small particle size in the particle size distribution measured by laser diffraction.

[0032] In this disclosure, “metal” includes both metals and metalloids such as silicon and germanium, in their elemental or ionic states.

[0033] In this disclosure, “alloy” means a mixture of two or more metals.

[0034] In the present disclosure, “electrode active material” means an electrode material capable of undergoing lithiation and delithiation.

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

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

[0037] In the present disclosure, “lithiation” and “lithiating” mean a process of adding lithium to an electrode active material.

[0038] In the present disclosure, “delithiation” and “delithiate” mean a process of removing lithium from an electrode active material.

[0039] In this disclosure, “charging” and “charging” mean a process of providing electrochemical energy to a battery.

[0040] In this disclosure, “discharging” and “discharging” mean the process of removing electrochemical energy from a battery.

[0041] In the present disclosure, “positive electrode” and “cathode” mean an electrode at which electrochemical reduction and lithiation occur during a discharge process.

[0042] In the present disclosure, “cathode” and “anode” mean electrodes where electrochemical oxidation and delithiation occur during the discharge process.

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

[0044] [Sulphide-based solid electrolyte]

[0045] A sulfide-based solid electrolyte according to one embodiment may include a compound having an argyrodite-type crystal structure and represented by the following chemical formula 1.

[0046] <Chemical Formula 1>

[0047] Li 7-a-c M a PS 6-b-c O b X C

[0048] In the above chemical formula 1,

[0049] The above M may include Na, K, Ca, Mg, Ag, Cu, Hf, In, Ti, Pb, Sb, Fe, Zn, Cr, B, Sn, Ge, Si, Zr, Ta, Nb, V, Ga, Al, As, or a combination thereof.

[0050] The above X may include Cl, Br, I, or a combination thereof.

[0051] 0 <a≤1, 0<b≤1, 및 1.5<c≤2 일 수 있다.

[0052] According to one embodiment, a sulfide-based solid electrolyte is a compound represented by the chemical formula 1, 0 <a≤0.1, 또는 0<a≤0.05 일 수 있다. 황화물계 고체 전해질은 구성 원소의 일부가 양이온으로 치환됨으로써 리튬 이온이 새로운 공극에 배치되어 전도성 경로(conduction pathway)를 통해 이온전도도를 개선할 수 있다. 이러한 황화물계 고체 전해질을 포함하는 전고체 전지는 사이클 특성이 개선될 수 있다.

[0053] According to one embodiment, a sulfide-based solid electrolyte is a compound represented by the chemical formula 1, 0 <b≤0.5, 0.1≤b≤0.5, 0.1≤b≤0.4, 또는 0.2≤b≤0.4 일 수 있다. 황화물계 고체 전해질은 우수한 셀특성을 구현하기 위해서는 전극 물질 간 접촉상태가 중요할 수 있다. 구현예에 따른 황화물계 고체 전해질은 구성 원소의 일부를 산소로 치환함으로써 치밀도를 향상시킬 수 있다. 이러한 황화물계 고체 전해질을 포함하는 전고체 전지는 열 안정성이 증가하고 발화 가능성이 감소할 수 있다.

[0054] According to one embodiment, a sulfide-based solid electrolyte is 1.65 in the chemical formula 1. <c≤2, 1.7<c≤2, 또는 1.7<c≤1.9 일 수 있다. 황화물계 고체 전해질에서 음이온 치환은 양이온 치환보다 상대적으로 리튬 이온 전도에 더 큰 영향을 미칠 수 있다. 아지로다이트(argyrodite) 타입 황화물계 고체 전해질은 구성 원소의 일부를 할로겐 음이온 원자로 대체하여 이온전도도를 개선할 수 있다. 이러한 황화물계 고체 전해질을 포함하는 전고체 전지는 사이클 특성을 개선할 수 있다.

[0055] According to one embodiment, a sulfide-based solid electrolyte may have 2≤b+c≤3, 2≤b+c≤2.5, or 2≤b+c≤2.2 in the chemical formula 1. A sulfide-based solid electrolyte satisfying the above range may have excellent ionic conductivity. A sulfide-based solid electrolyte satisfying the above range may have good contact between a positive electrode active material and a solid electrolyte or between solid electrolytes, thereby improving density and thermal stability. An all-solid-state battery including such a sulfide-based solid electrolyte may have improved thermal stability.

[0056] The ionic conductivity of the sulfide-based solid electrolyte according to one embodiment may be, for example, 2 mS / cm to 5 mS / cm, 2.3 mS / cm to 4 mS / cm, or 2.5 mS / cm to 3 mS / cm at 25° C. Since the sulfide-based solid electrolyte has an ionic conductivity in this range, ion transfer between the positive electrode and the negative electrode in an all-solid-state battery including the sulfide-based solid electrolyte can be effectively performed, thereby reducing the internal resistance between the positive electrode and the negative electrode. The ionic conductivity can be measured using a DC polarization method. Alternatively, the ionic conductivity can be measured using a complex impedance method.

[0057] Referring to FIG. 1, a sulfide-based solid electrolyte according to an embodiment may have a first exothermic peak (hereinafter, referred to as a first exothermic peak) that appears at 200°C or higher when heat flow is measured by differential scanning calorimetry (DSC). Since the sulfide-based solid electrolyte has this exothermic peak, side reactions may be suppressed below 200°C. A solid electrolyte including such a sulfide-based solid electrolyte may have improved thermal stability. A sulfide-based solid electrolyte according to an embodiment may have a first exothermic peak that appears at 200°C to 300°C or 200°C to 250°C when heat flow is measured by differential scanning calorimetry (DSC).

[0058] Referring to FIG. 1, a sulfide-based solid electrolyte according to one embodiment may have a maximum heat flow of 5 W / g or less, 4 W / g or less, 3 W / g or less, or 2 W / g or less when heat flow is measured by differential scanning calorimetry (DSC).

[0059] According to an embodiment, a sulfide-based solid electrolyte may have a maximum heat flow of 3 W / g or less or 2 W / g or less at a temperature of 300°C or higher when heat flow is measured by differential scanning calorimetry (DSC). According to an embodiment, a sulfide-based solid electrolyte may have a maximum heat flow of 5 W / g or less, 4 W / g or less, 3 W / g or less, or 2 W / g or less at a temperature of 300°C to 400°C when heat flow is measured by differential scanning calorimetry (DSC). According to an embodiment, a sulfide-based solid electrolyte may have a maximum heat flow of 5 W / g or less, 4 W / g or less, 3 W / g or less, or 2 W / g or less at 400°C to 500°C when heat flow is measured by differential scanning calorimetry (DSC). Since the maximum heat flow at high temperatures is small in the sulfide-based solid electrolyte even when the temperature inside the battery rapidly increases due to thermal runaway or the like, the possibility of ignition is low and the risk of explosion can be reduced. According to an embodiment, a sulfide-based solid electrolyte may have a maximum heat flow of 1 W / g to 2 W / g at 200°C to 250°C when heat flow is measured by differential scanning calorimetry (DSC), and a maximum heat flow of 0.1 W / g to 1 W / g at 300°C to 500°C.

[0060] The volume-based D50 particle size of a sulfide-based solid electrolyte measured by laser diffraction particle size distribution measurement is, for example, 0.5 ㎛ to 6.5 ㎛, 0.5 ㎛ to 6 ㎛, 0.5 ㎛ to 5 ㎛, 0.5 ㎛ to 4.5 ㎛, or 0.5 ㎛ to 3.9 ㎛. Since the sulfide-based solid electrolyte has a D50 particle size, i.e., an average particle size, in this range, it can be suitably used in a positive electrode layer of an all-solid-state secondary battery. Since the sulfide-based solid electrolyte has an average particle size in this range, it can effectively cover the surface of positive electrode active material particles and effectively fill the voids between positive electrode active material particles. Therefore, the cycle characteristics of an all-solid-state secondary battery employing a positive electrode layer including such a sulfide-based solid electrolyte can be further improved. If the average particle size of the sulfide-based solid electrolyte increases excessively, it may be difficult to uniformly coat the surface of the positive electrode active material, and the internal resistance of the positive electrode may increase due to an increase in the pores between the sulfide-based solid electrolyte particles, and the cycle characteristics of an all-solid-state secondary battery including such a positive electrode may deteriorate. If the average particle size of the sulfide-based solid electrolyte decreases excessively, its suitability for the electrode manufacturing process may be reduced due to aggregation, etc.

[0061] The volume-based D10 particle size measured by laser diffraction particle size distribution measurement of the sulfide-based solid electrolyte is, for example, 0.1 ㎛ to 2 ㎛, 0.3 ㎛ to 2 ㎛, or 0.5 ㎛ to 2 ㎛.

[0062] The volume-based D90 particle size measured by laser diffraction particle size distribution measurement of the sulfide-based solid electrolyte is, for example, 1 µm to 20 µm, 1 µm to 15 µm, 3 µm to 15 µm, 3 µm to 12 µm or 5 µm to 12 µm.

[0063] The sulfide-based solid electrolyte may have, for example, a narrow range of particle size distribution. The D90 - D10 value of the sulfide-based solid electrolyte is, for example, 1 to 30 μm, 1 to 25 μm, 1 to 20 μm, 1 to 15 μm, 1 to 10 μm, 1 to 7 μm, or 3 to 7 μm. Since the sulfide-based solid electrolyte has such a narrow range of D90 - D10 values, uneven distribution due to agglomeration of the sulfide-based solid electrolyte particles can be prevented during the manufacturing process of the positive electrode layer.

[0064] The particle size distribution of a sulfide-based solid electrolyte measured by laser diffraction particle size distribution measurement may have, for example, a monomodal peak or a bimodal peak. A sulfide-based solid electrolyte having a monomodal peak in its particle size distribution has a narrow range of particle size distribution, so that the sulfide-based solid electrolyte can be more uniformly arranged, for example, within a cathode. A sulfide-based solid electrolyte having a bimodal peak in its particle size distribution has small-diameter particles arranged between large-diameter particles, so that the sulfide-based solid electrolyte can be more densely arranged, for example, within a cathode.

[0065] The sulfide-based solid electrolyte may be in powder or molded form. The solid electrolyte in molded form may be, but is not limited to, pellets, sheets, or thin films, and may take various forms depending on the intended use.

[0066] [All-solid-state battery]

[0067] Referring to FIG. 3, an all-solid-state battery (10) according to another embodiment may include a positive electrode layer (100) including a positive electrode active material layer (120); a negative electrode layer (200); and a solid electrolyte layer (300) disposed between the positive electrode layer (100) and the negative electrode layer (200).

[0068] The solid electrolyte layer (300) is disposed between the positive electrode layer (100) and the negative electrode layer (200) and may include a solid electrolyte and a binder.

[0069] The solid electrolyte included in the solid electrolyte layer (300) may include a sulfide-based solid electrolyte including a compound represented by the chemical formula 1 described above according to one embodiment. An all-solid-state battery (10) including such a sulfide-based solid electrolyte may have increased thermal stability, a reduced possibility of ignition, and improved cycle characteristics.

[0070] The solid electrolyte included in the solid electrolyte layer (300) may have a bulk density relative to a true density of 0.82 to 1, 0.85 to 1, or 0.87 to 1. The sulfide-based solid electrolyte included in the cathode active material layer (120) according to an embodiment may have a bulk density relative to a true density of less than 1, 0.99 or less, 0.95 or less, or 0.90 or less. The sulfide-based solid electrolyte according to an embodiment can easily compress the powder when pressurized, thereby realizing a bulk density relative to a true density within this range. The sulfide-based solid electrolyte included in the cathode active material layer (120) satisfying this range can easily expand the contact area with the cathode active material, thereby realizing excellent cell characteristics.

[0071] The density of the solid electrolyte included in the solid electrolyte layer (300) may be 1.5 g / cc to 2.0 g / cc. Since the solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state battery (10) is reduced, and the defect of the solid electrolyte membrane being penetrated and short-circuited due to the formation of lithium dendrites can be prevented. The elastic modulus of the solid electrolyte is, for example, 15 GPa to 35 GPa.

[0072] According to another embodiment, the solid electrolyte included in the solid electrolyte layer (300) may further include a solid electrolyte such as a sulfide-based solid electrolyte and / or an oxide-based solid electrolyte other than the sulfide-based solid electrolyte including the compound represented by the above-described chemical formula 1 according to one embodiment. For example, Li2S-P2S5, Li2S-P2S5-LiX, X is a halogen element, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n , m, n are positive numbers, Z is one of Ge, Zn or Ga, Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q , p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga In, Li 7-x PS 6-x Cl x , 0≤x≤2, Li 7-x PS 6-x Br x , 0≤x≤2, and Li 7-x PS 6-x I x , one or more selected from 0≤x≤2 and / or, Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0≤x<1, 0≤y<1), PB(Mg3Nb 2 / 3)O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Li3PO4, Li x Ti y (PO4)3(0 <x<2, 0<y<3), Li x Al y Ti z (PO4)3(0 <x<2, 0<y<1, 0<z<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1 0≤y≤1), Li x La y TiO3(0 <x<2, 0<y<3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2, Li 3+x La3M2O 12 (M = Te, Nb, or Zr, 0≤x≤10), Li7La3Zr2O 12 (LLZO) and Li 3+x La3Zr 2-a M a O 12 (M doped LLZO, M=Ga, W, Nb, Ta, or Al, 0 <a<2, 0≤x≤10) 중에서 선택된 가넷계(Garnet-type) 고체전해질 등이나 이들로 한정되지 않으며 당해 기술 분야에서 고체전해질로 사용하는 것이라면 모두 가능하다.

[0073] The binder included in the solid electrolyte layer (300) may be, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited thereto, and any binder used in the relevant technical field may be used. The binder may be omitted.

[0074] The content of the binder included in the solid electrolyte layer (300) is 0.1 to 10 wt%, 0.1 to 5 wt%, 0.1 to 3 wt%, 0.1 to 1 wt%, 0 to 0.5 wt%, or 0 to 0.1 wt% with respect to the total weight of the solid electrolyte layer (300). The binder may be omitted.

[0075] The thickness of the solid electrolyte layer (300) may be 10 μm to 200 μm. If the solid electrolyte layer (300) has such a thickness, the ionic conductivity of the solid electrolyte layer (300) may be improved.

[0076] Referring to FIG. 3, the positive electrode layer (100) may include a positive electrode current collector (110) and a positive electrode active material layer (120) disposed on the positive electrode current collector (110). The positive electrode active material layer (120) may include a positive electrode active material, a solid electrolyte, a conductive material, and a binder.

[0077] The positive electrode current collector (110) can provide a reference surface on which the positive electrode active material layer (120) is arranged. The positive electrode current collector (110) can include a plate or foil including, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel (SUS), titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

[0078] According to another embodiment, the positive electrode current collector (110) may be omitted. Although not illustrated, a carbon layer having a thickness of 0.1 μm to 4 μm may be further disposed between the positive electrode current collector (110) and the positive electrode active material layer (120) to increase the bonding strength between the positive electrode current collector (110) and the positive electrode active material layer (120). The carbon layer may include amorphous carbon, crystalline carbon, or the like.

[0079] The positive electrode active material layer (120) may include a positive electrode active material.

[0080] The positive electrode active material included in the positive electrode active material layer (120) is a material that can reversibly absorb and desorb lithium ions. The positive electrode active material may include, but is not necessarily limited to, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, and lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide. The positive electrode active materials may be used alone or as a mixture of two or more.

[0081] Lithium transition metal oxides include, for example, Li a A 1-b B b D2(0.90≤a≤1, 0≤b≤0.5), Li a E 1-b B b O 2-c D c (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05), LiE 2-b B b O 4-c D c (0≤b≤0.5, 0≤c≤0.05), Li a Ni 1-b-c Co b B c D α (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 (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 Dα (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2), Li a Nor 1-b-c Mn b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Nor b E c G d O2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1), Li a Nor b Co c Mn d GeO2(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(0.9≤a≤1, 0.001≤b≤0.1), Li a CoG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a MnG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a Mn2GbO4(0.90≤a≤1, 0.001≤b≤0.1), QO2, QS2, LiQS2, V2O5, LiV2O5, LiIO2, LiNiVO4, Li 3-f J2(PO4)3(0≤f≤2), Li 3-fA compound represented by any one of Fe2(PO4)3(0≤f≤2), LiFePO4. In these compounds, the capital letter “A” is Ni, Co, Mn, or a combination thereof, the capital letter “B” is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof, the capital letter “D” is O, F, S, P, or a combination thereof, the capital letter “E” is Co, Mn, or a combination thereof, the capital letter “F” is F, S, P, or a combination thereof, the capital letter “G” is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof, the capital letter “Q” is Ti, Mo, Mn, or a combination thereof, the capital letter “I” is Cr, V, Fe, Sc, Y, or a combination thereof, and the capital letter “J” is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0082] The positive electrode active material included in the positive electrode active material layer (120) 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 atomic layers and metal atomic layers are alternately and regularly arranged in a direction, and thereby each atomic layer forms a two-dimensional plane. The "cubic rock salt structure" refers to the sodium chloride type (NaCl type) structure, which is a type of crystal structure, and specifically refers to a structure in which the face-centered cubic lattice (fcc) formed by each cation and anion is arranged with a displacement of half of the ridge of the unit lattice. Lithium transition metal oxides having this layered rock salt structure include, for example, LiNi x Co y Al z O2(NCA) or LiNi x Coy Mn z O2(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.

[0083] The above-described compound included in the positive electrode active material layer (120) may be covered by a coating layer (not shown). The positive electrode active material may also be a mixture of the above-described compound and a compound to which a coating layer is added. Meanwhile, the coating layer added to the surface of the positive electrode active material may include, for example, an oxide, a hydroxide, an oxyhydroxide, an oxycarbonate, or a hydroxycarbonate of the coating elements below. The compound forming the coating layer is 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 of forming the coating layer is selected within a range that does not adversely affect the physical properties of the positive electrode active material. The method of forming the coating layer is, for example, spray coating, dipping, etc.

[0084] When the positive electrode active material included in the positive electrode active material layer (120) is a ternary lithium transition metal oxide such as NCA or NCM and includes nickel (Ni), the capacity density of the all-solid-state battery (10) can be increased, thereby reducing metal dissolution of the positive electrode active material in a charged state. As a result, the cycle characteristics of the all-solid-state battery (10) in a charged state are improved. Meanwhile, the “cycle characteristics” are characteristics indicating the degree to which the all-solid-state battery (10) is deteriorated by charge / discharge of the all-solid-state battery (10). In an all-solid-state battery (10) with high cycle characteristics, the degree to which the all-solid-state battery (10) is deteriorated by charge / discharge is small, and in an all-solid-state battery (10) with low cycle characteristics, the degree to which the all-solid-state battery (10) is deteriorated by charge / discharge is large.

[0085] The shape of the positive electrode active material included in the positive electrode active material layer (120) may include, for example, a particle shape such as a sphere or an ellipsoid. The particle size and content of the positive electrode active material are not particularly limited.

[0086] The positive electrode active material layer (120) may include a solid electrolyte.

[0087] The solid electrolyte included in the positive electrode active material layer (120) may be the same as or different from any one of the materials that may be included in the solid electrolyte included in the above-described solid electrolyte layer (300). The solid electrolyte included in the positive electrode active material layer (120) may include a sulfide-based solid electrolyte including a compound represented by the above-described chemical formula 1 according to one embodiment. An all-solid-state battery (10) including such a sulfide-based solid electrolyte may have increased thermal stability, a reduced possibility of ignition, and improved cycle characteristics.

[0088] The solid electrolyte included in the positive electrode active material layer (120) may have a smaller median particle size (D50) than the solid electrolyte included in the solid electrolyte layer (300). For example, the median particle size (D50) of the solid electrolyte included in the positive electrode active material layer (120) may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the median particle size (D50) of the solid electrolyte included in the solid electrolyte layer (300). Meanwhile, the median particle size (D50) may be a median diameter measured using a laser particle size distribution meter.

[0089] The positive electrode active material layer (120) may include a conductive material. The conductive material may have conductivity without causing chemical changes in the all-solid-state battery (10), thereby increasing the conductivity of the positive electrode active material and the solid electrolyte. The conductive material may include a carbon-based material. The conductive material may include, for example, one or more selected from graphite, carbon black, acetylene black, carbon nanofibers, and carbon nanotubes.

[0090] The positive electrode active material layer (120) may further include additives such as fillers, coating agents, dispersants, and ion-conducting aids in addition to the above-described positive electrode active material, solid electrolyte, binder, and conductive agent. As the fillers, coating agents, dispersants, and ion-conducting aids that the positive electrode active material layer (120) may include, known materials generally used in electrodes of all-solid-state batteries may be used.

[0091] Referring to FIG. 3, a negative electrode layer (200) according to one embodiment may include a negative electrode current collector (210) and a negative electrode active material layer (220a) disposed on the negative electrode current collector (210). Referring to FIG. 3, a negative electrode layer (200) according to another embodiment may include a negative electrode current collector (210) and a negative electrode coating layer (220b) disposed on the negative electrode current collector (210).

[0092] The negative electrode current collector (210) can provide a reference surface on which the negative electrode active material layer (220a) or the negative electrode coating layer (220b) is arranged. The negative electrode current collector (210) can include, for example, a material that does not react with lithium, i.e., does not form an alloy or compound with lithium. The material constituting the negative electrode current collector (210) can include, for example, 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 can be 1 to 20 μm, for example, 5 to 15 μm, for example, 7 to 10 μm.

[0093] The negative electrode current collector (210) may be composed of one of the above-described metals, or may include an alloy or coating material of two or more metals. The negative electrode current collector (210) is, for example, in the form of a plate or foil. In another embodiment, the negative electrode current collector (210) may be omitted.

[0094] Referring to FIG. 3, a negative electrode layer (200) according to one embodiment may include a negative electrode current collector (210) and a negative electrode active material layer (220a) disposed on the negative electrode current collector (210), and the negative electrode active material layer (220a) may include a negative electrode active material.

[0095] The negative active material in the negative active material layer (220a) includes a material capable of reversibly intercalating / deintercalating lithium ions, a lithium metal, an alloy of a lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0096] Materials capable of reversibly intercalating / deintercalating lithium ions include carbon-based negative electrode active materials, such as crystalline carbon, amorphous carbon, or a combination thereof. Examples of crystalline carbon include graphite, such as natural graphite or artificial graphite in an amorphous, plate-like, flake-like, spherical, or fibrous form, and examples of amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, and calcined coke.

[0097] As an alloy of lithium metal, an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn can be used.

[0098] As a material capable of doping and dedoping lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used. The Si-based negative electrode active material can be silicon, a silicon-carbon composite, SiOx (0 < x < 2), a Si-Q alloy (Q is selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements (excluding Si), Group 15 elements, Group 16 elements, transition metals, rare earth elements, and combinations thereof), or a combination thereof. The Sn-based negative electrode active material can be Sn, SnO2, a Sn-based alloy, or a combination thereof.

[0099] The silicon-carbon composite may be a composite of silicon and amorphous carbon. In one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, the composite may include secondary particles (cores) in which silicon primary particles are assembled, and an amorphous carbon coating layer (shell) positioned on the surface of the secondary particles. The amorphous carbon may also be positioned between the silicon primary particles, such that, for example, the silicon primary particles may be coated with amorphous carbon. The secondary particles may be dispersed in the amorphous carbon matrix.

[0100] The silicon-carbon composite may further comprise crystalline carbon. For example, the silicon-carbon composite may comprise a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer positioned on the surface of the core.

[0101] The Si-based negative electrode active material or the Sn-based negative electrode active material can be used in combination with the carbon-based negative electrode active material.

[0102] Referring to FIG. 4, a cathode layer (200) according to another embodiment may include a cathode current collector (210) and a cathode coating layer (220b) disposed on the cathode current collector (210).

[0103] The negative electrode coating layer (220b) can be configured to allow lithium metal to grow between it and the negative electrode current collector (210) when the all-solid-state battery (10) is charged. The negative electrode coating layer (220b) can serve as a protective layer for the lithium metal and simultaneously suppress the precipitation and growth of lithium dendrites.

[0104] The cathode coating layer (220b) may include a metal-carbon composite. The metal-carbon composite may be a composite of metal particles and a carbon-based material. The metal-carbon composite may have, for example, a particle shape. The average particle diameter of the metal-carbon composite having a particle shape is, for example, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, or 900 nm or less. The average particle diameter of the metal-carbon composite having a particle shape is, for example, 10 nm to 4 μm or less, 10 nm to 3 μm or less, 10 nm to 2 μm or less, 10 nm to 1 μm or less, or 10 nm to 900 nm or less. Since the metal-carbon composite has an average particle diameter in this range, reversible absorption and / or desorption of lithium may be facilitated during charge and discharge. The average particle size of the metal-carbon composite is, for example, the median diameter (D50) measured using a laser particle size distribution meter.

[0105] The metal particles in the metal-carbon composite may include at least one metal or metalloid selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The carbonaceous material in the metal-carbon composite may include at least one selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene. The carbonaceous material in the metal-carbon composite may be amorphous carbon. Amorphous carbon may be carbon that has no crystallinity or very low crystallinity.

[0106] The mixing ratio of the metal particles and the carbon-based material included in the cathode coating layer (220b) may be, for example, a weight ratio of 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1. The content of the metal particles included in the cathode coating layer (220b) may be 8 to 60 wt%, 10 to 50 wt%, 15 to 40 wt%, or 20 to 30 wt% based on the total weight of the metal-carbon composite. When the metal particles have a content within this range, the cycle characteristics of the all-solid-state battery (1) may be improved.

[0107] The cathode coating layer (220b) may further include additives other than the metal-carbon composite. The cathode coating layer (220b) may further include, for example, at least one additive selected from the group consisting of a binder, a filler, a coating agent, a dispersant, and an ion-conducting auxiliary agent.

[0108] The negative electrode coating layer (220b) may have a smaller thickness than the positive electrode active material layer (120). The thickness of the negative electrode coating layer (220b) 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 (220b) may be, for example, 1 um to 20 um, 2 um to 10 um, or 3 um to 7 um. If the thickness of the negative electrode coating layer (220b) is too thin, lithium dendrites formed between the negative electrode coating layer (220b) and the negative electrode current collector (210) may cause the negative electrode coating layer (220b) to collapse, thereby deteriorating the cycle characteristics of the all-solid-state battery (10). If the thickness of the cathode coating layer (220b) increases excessively, the energy density of the all-solid-state battery (10) may decrease and the internal resistance of the all-solid-state battery (10) due to the cathode coating layer (220b) may increase, thereby deteriorating 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 (220b) and the solid electrolyte layer (300).

[0110] FIG. 5 is for explaining an all-solid-state battery (10) according to another embodiment. Referring to FIG. 5, an all-solid-state battery (10) according to one embodiment may further include a lithium metal layer (240) disposed between an anode current collector (210) and a solid electrolyte layer (300) by charging. An all-solid-state battery (10) according to one embodiment may further include a lithium metal layer (240) disposed between an anode current collector (210) and an anode coating layer (220b) by charging. Although not shown in the drawing, an all-solid-state battery (10) may further include a lithium metal layer (240) disposed between a solid electrolyte layer (300) and an anode coating layer (220b) by charging. Although not shown in the drawing, an all-solid-state battery (10) may further include a lithium metal layer (240) disposed inside an anode coating layer (220b) by charging.

[0111] The lithium metal layer (240) may include lithium or a lithium alloy. Since the lithium metal layer (240) is a metal layer containing lithium, it may function as a lithium reservoir, for example. The lithium alloy may be, but is not limited to, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy, etc., and any lithium alloy used in the art may be used. The lithium metal layer (240) may be made of one of these alloys or lithium, or may be made of several types of alloys. The lithium metal layer (240) may be, for example, a plated layer. The lithium metal layer (240) may be deposited between the negative electrode coating layer (220b) and the negative electrode current collector (210), for example, during the charging process of the all-solid-state battery (10).

[0112] Thickness (d) of lithium metal layer (240) 240 ) is not particularly limited, but may be, for example, 1 μm to 500 μm, 1 μm to 200 μm, 1 μm to 150 μm, 1 μm to 100 μm, or 1 μm to 50 μm. If the thickness of the lithium metal layer (240) is too thin, it may be difficult for the lithium metal layer (240) to perform the role of a lithium reservoir. If the thickness of the lithium metal layer (240) is too thick, the mass and volume of the all-solid-state battery (10) may increase, and the cycle characteristics of the all-solid-state battery (10) may rather deteriorate.

[0113] In another embodiment, the lithium metal layer (240) in the negative electrode layer (200) may be provided between the negative electrode current collector (210) and the negative electrode coating layer (220b), for example, before assembling the all-solid-state battery (10). When the lithium metal layer (240) is disposed between the negative electrode current collector (210) and the negative electrode coating layer (220b) before assembling the all-solid-state battery (10), the lithium metal layer (240) acts as a lithium reservoir because it is a metal layer containing lithium. For example, a lithium foil may be disposed between the negative electrode current collector (210) and the negative electrode coating layer (220b) before assembling the all-solid-state battery (10).

[0114] When the lithium metal layer (240) is precipitated by charging after assembling the all-solid-state battery (10), the energy density of the all-solid-state battery (10) can increase because the lithium metal layer (240) is not included during the assembly of the all-solid-state battery (10). When charging the all-solid-state battery (10), the charging can exceed the charging capacity of the negative electrode coating layer (220b). That is, the negative electrode coating layer (220b) is overcharged. At the initial stage of charging, lithium can be absorbed into the negative electrode coating layer (220b). When charging exceeds the capacity of the negative electrode coating layer (220b), lithium can be precipitated, for example, between the negative electrode coating layer (220b) and the negative electrode current collector (210). The precipitated lithium can form a lithium metal layer (230).

[0115] The lithium metal layer (240) may be mainly composed of lithium (i.e., metallic lithium). When discharging, lithium in the lithium metal layer (240) may be ionized and move to the positive electrode layer (100). In other words, lithium may be used as an anode active material in the all-solid-state battery (10). In addition, since the anode coating layer (220b) covers the lithium metal layer (240), the anode coating layer (220b) may protect the lithium metal layer (240) and simultaneously suppress the precipitation and growth of lithium dendrites. Therefore, the anode coating layer (220b) may suppress short-circuiting and capacity degradation of the all-solid-state battery (10) and improve the cycle characteristics of the all-solid-state battery (10).

[0116] When a lithium metal layer (240) is formed by charging after assembling the all-solid-state battery (10), the negative electrode layer (200), i.e., the negative electrode current collector (210) and the negative electrode coating layer (220b) and the region therebetween may be a Li-free region that does not contain lithium (Li) in the initial state of the all-solid-state battery (10) or in the state after complete discharge.

[0117]

[0118] Fig. 6 is for explaining an all-solid-state battery (10) according to another embodiment. Referring to Fig. 6, an all-solid-state battery (10) according to one embodiment may further include an intermediate layer (130) disposed between a positive electrode current collector (110) and a positive electrode active material layer (120).

[0119] The intermediate layer (130) may be directly disposed on, for example, one side or both sides of the positive electrode current collector (110). No other layer may be disposed between the positive electrode current collector (110) and the intermediate layer (130). By directly disposing the intermediate layer (130) on one side or both sides of the positive electrode current collector (110), the bonding force between the positive electrode current collector (110) and the positive electrode active material layer (120) may be further improved. By disposing the intermediate layer (130) between the positive electrode current collector (110) and the positive electrode active material layer (120), side reactions between the inorganic filler and / or solid electrolyte and the positive electrode current collector (110) may be more effectively suppressed. Therefore, deterioration of the all-solid-state battery (10) during the charge / discharge process may be suppressed, and the cycle characteristics of the all-solid-state battery (10) may be further improved.

[0120] Thickness (d) of the middle layer (130) 130 ) is, for example, 0.01 to 20%, 0.1 to 20%, 0.5 to 20%, 1 to 20%, 1 to 15%, 1 to 10%, 2 to 8%, or 3 to 7% of the thickness of the positive electrode current collector (110). The thickness of the intermediate layer (130) is, for example, 10 nm to 5 ㎛, 50 nm to 5 ㎛, 200 nm to 4 ㎛, 500 nm to 3 ㎛, 500 nm to 2 ㎛, 500 nm to 1.5 ㎛, or 700 nm to 1.3 ㎛. When the intermediate layer (130) has a thickness in this range, the bonding force between the positive electrode current collector (110) and the positive electrode active material layer (120) is further improved, and an increase in interface resistance is suppressed. The thickness (d) of the intermediate layer (130) 130 ) can be measured, for example, from scanning electron microscope (SEM) images of the intermediate layer cross-section.

[0121] The intermediate layer (130) includes, for example, a carbon-based conductive material. The carbon-based conductive material included in the intermediate layer (130) may be selected from among the carbon-based conductive materials used in the positive electrode active material layer (120). The intermediate layer (130) may include the same carbon-based conductive material as the carbon-based conductive material used in the positive electrode active material layer (120). Since the intermediate layer (130) includes a carbon-based conductive material, the intermediate layer (130) may be, for example, a conductive layer.

[0122] The intermediate layer (130) may additionally include, for example, a binder. By additionally including a binder in the intermediate layer (130), the bonding strength between the positive electrode current collector (110) and the positive electrode active material layer (120) may be further improved. The binder included in the intermediate layer (130) may be, for example, a conductive binder or a non-conductive binder. The conductive binder may be, for example, an ion-conductive binder and / or an electron-conductive binder. A binder having both ion-conductive and electron-conductive properties may belong to both an ion-conductive binder and an electron-conductive binder.

[0123] The binder included in the intermediate layer (130) may be selected from among the binders used in the positive electrode active material layer (120). The intermediate layer (130) may include the same binder as the binder used in the positive electrode active material layer (120). The binder included in the intermediate layer (130) is, for example, a fluorine-based binder. The fluorine-based binder included in the intermediate layer (130) is, for example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or a combination thereof. The intermediate layer (130) may be, for example, a bonding layer including a binder. The intermediate layer (130) may be, for example, a conductive layer including a binder and a carbon-based conductive material.

[0124] The intermediate layer (130) may be disposed on the positive electrode current collector (110) in a dry or wet manner, for example. The intermediate layer (130) may be disposed on the positive electrode current collector (110) in a dry manner, for example, by deposition such as CVD or PVD. The intermediate layer (130) may be disposed on the positive electrode current collector (110) in a wet manner, for example, by spin coating, dip coating, or the like. The intermediate layer (130) may be disposed on the positive electrode current collector (110) in a wet manner, for example, by deposition of a carbon-based conductive material on a substrate. The dry-coated intermediate layer (130) may be made of a carbon-based conductive material and may not include a binder. The intermediate layer (130) may be disposed on the positive electrode current collector (110) in a dry manner, for example, by coating a composition including a carbon-based conductive material, a binder, and a solvent on the surface of the electrode current collector and drying it. The intermediate layer (130) may have a single-layer structure or a multi-layer structure including a plurality of layers. The multilayer structure may be a two-layer structure, a three-layer structure, a four-layer structure, etc. In one embodiment, the positive electrode layer (100) may have a positive electrode active material layer (120) directly disposed on the positive electrode current collector (110). In one embodiment, another layer, for example, an intermediate layer, may not be disposed between the positive electrode current collector (110) and the positive electrode active material layer (120).

[0125]

[0126] FIG. 6 is for explaining an all-solid-state battery (10) according to another embodiment. Referring to FIG. 6, an all-solid-state battery (10) according to one embodiment may further include a thin film (230) including an element capable of forming an alloy with lithium on an anode current collector (210). The thin film (230) may be disposed between the anode current collector (210) and the anode coating layer (220b). The thin film (230) may include, for example, an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium includes, but is not limited to, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., and any element capable of forming an alloy with lithium in the art may be used. The thin film (230) may be composed of one of these metals or an alloy of several types of metals.

[0127] Referring to FIG. 7, by placing a thin film (230) on one surface of a negative electrode current collector (210), for example, the deposition shape of a lithium metal layer (240) deposited between the thin film (230) and the negative electrode coating layer (220b) becomes flatter, and the cycle characteristics of the all-solid-state battery (10) can be further improved.

[0128] Thickness (d) of the thin film (230) 230) may be, for example, 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. If the thickness of the thin film (230) is less than 1 nm, it may be difficult for the function of the thin film (230) to be exerted. If the thickness of the thin film (230) is excessively thick, the thin film (230) itself may absorb lithium, thereby reducing the amount of lithium precipitated from the negative electrode, thereby lowering the energy density of the all-solid-state battery (10) and deteriorating the cycle characteristics of the all-solid-state battery (10). The thin film (230) may be disposed on the negative electrode current collector (210) by, for example, a vacuum deposition method, a sputtering method, a plating method, or the like, but is not necessarily limited to these methods, and any method capable of forming the thin film (230) in the relevant technical field may be used.

[0129]

[0130] Fig. 8 is for explaining an all-solid-state battery (10) according to another embodiment. Referring to Fig. 8, an all-solid-state battery (10) according to one embodiment has a width (W) of a positive electrode layer (100) 100 ) is the width (W) of the cathode layer (200) 200 ) may be smaller than the width (W) of the cathode layer (200) of the all-solid-state battery (10) according to one embodiment. 200 ) and the width of the solid electrolyte layer (300) may have substantially the same area. The all-solid-state battery (10) according to one embodiment may further include a gasket (400). The gasket (400) may be arranged to surround the positive electrode layer (100). The gasket (400) may fill the lateral step of the all-solid-state battery (10) caused by the width difference between the positive electrode layer (100) and the negative electrode layer (200). The gasket (400) may surround four sides of the positive electrode layer (100). For example, the thickness of the gasket (400) may be substantially the same as the thickness of the positive electrode layer (100).

[0131]

[0132] Fig. 9 is for explaining an all-solid-state battery (10) according to another embodiment. Referring to Fig. 9, a solid electrolyte layer (300) of an all-solid-state battery (10) according to one embodiment may include a first solid electrolyte layer (310) and a second solid electrolyte layer (320). The first solid electrolyte layer (310) may be adjacent to the positive electrode layer (100), and the second solid electrolyte layer (320) may be adjacent to the negative electrode layer (200). The thickness (d) of the first solid electrolyte layer (310) 310 ) is the thickness (d) of the second solid electrolyte layer (320). 320 ) may be smaller than the positive electrode layer (100). Referring to FIG. 8, the first solid electrolyte layer (310) according to one embodiment may have substantially the same width as the positive electrode layer (100). The second solid electrolyte layer (320) may have substantially the same width as the negative electrode layer (200). The all-solid-state battery (10) according to one embodiment may further include a gasket (400). Referring to FIG. 9, the gasket (400) may be arranged to surround the positive electrode layer (100) and the first solid electrolyte layer (310).

[0133] The present invention is further explained in detail through the following examples and comparative examples. However, the examples are intended to illustrate the invention and are not intended to limit the scope of the invention.

[0134] Comparative Example 1

[0135] (Manufacture of solid electrolyte)

[0136] A precursor mixture was obtained by mixing Li2S, LiCl, and P2S5. The contents of Li2S, LiCl, and P2S5 were stoichiometrically weighed and controlled during the preparation of the precursor mixture so as to obtain Li6PS5Cl. The precursor mixture thus obtained was mechanically milled using a high-energy mill (Pulnerisette 7) for 20 hours. The mechanical milling was performed at a rotation speed of 380 rpm, 25°C, and argon atmosphere for 20 hours. 300 mg of the powder obtained from the mechanical milling was heat-treated at 500°C in a vacuum atmosphere for 12 hours to obtain a solid electrolyte.

[0137] (Manufacturing of all-solid-state batteries)

[0138] Cathode active material LiNi 0.8 Co 0.15 Al 0.5 O2(NCA), a sulfide-based solid electrolyte (Li6PS5Cl), and a conductive material, carbon nanofibers, were mixed in a weight ratio of 60:35:5 and then mixed for 15 minutes to prepare a cathode slurry. The prepared cathode slurry was molded into a sheet shape to manufacture a cathode sheet, and the cathode sheet was used as a cathode layer.

[0139] Li foil was prepared and used as the cathode layer.

[0140] The solid electrolyte (Li6PS5Cl) manufactured above was manufactured into pellets and used as a solid electrolyte layer.

[0141] A torque cell-type all-solid-state battery was manufactured by sequentially stacking a cathode layer, a solid electrolyte layer, and a cathode layer and then applying pressure.

[0142] Comparative Example 2

[0143] The contents of Li2S, LiCl and P2S5 are Li 5.3 PS 4.3 Cl 1.7A solid electrolyte was obtained and an all-solid-state battery was manufactured in the same manner as in Comparative Example 1, except that the stoichiometry was changed so that .

[0144] Example 1

[0145] When preparing the precursor mixture, use more Li2O, CuS, and Li2S, LiCl, P2S 5, The contents of Li2O and CuS are Li 5.27 Cu 0.03 PS4O 0.3 Cl 1.7 A solid electrolyte was obtained and an all-solid-state battery was manufactured in the same manner as in Comparative Example 1, except that the stoichiometry was changed so that .

[0146] Example 2

[0147] When preparing the precursor mixture, use more Li2O, CuS, and Li2S, LiCl, P2S 5, The contents of Li2O and CuS are Li 5.07 Cu 0.03 PS 3.8 O 0.3 Cl 1.9 A solid electrolyte was obtained and an all-solid-state battery was manufactured in the same manner as in Comparative Example 1, except that the stoichiometry was changed so that .

[0148] Evaluation Example 1: DSC Measurement of Sulfide-Based Solid Electrolyte

[0149] The torque cells manufactured in Examples 1 to 2 and Comparative Examples 1 to 2 were disassembled to recover the sulfide-based solid electrolyte powder contained in the positive electrode layer.

[0150] Heat flow was measured while heating the recovered sulfide-based solid electrolyte from 50°C to 400°C at a rate of 5°C / min, and part of the measurement results is shown in Figure 1 below (using TA instrument explorer a Q200).

[0151] In the case of Examples 1 and 2, the maximum value of heat flow was 2 W / g or less in the entire measured section (50°C to 400°C), but in the case of Comparative Examples 1 and 2, the maximum value of heat flow was 2 W / g or more, and in particular, the heat flow increased rapidly in the section from 300°C to 400°C.

[0152] Evaluation Example 2: Calculation of Apparent Density Compared to True Density of Sulfide-Based Solid Electrolyte

[0153] The torque cells manufactured in Examples 1 to 2 and Comparative Examples 1 to 2 were disassembled to recover the sulfide-based solid electrolyte powder contained in the positive electrode layer.

[0154] 200 mg of the recovered sulfide-based solid electrolyte was pressurized at 4 tons for 2 minutes using a 13 pi diameter torque cell to produce pellets. The thickness of the pellets produced in this way was measured to calculate the bulk density of the sulfide-based solid electrolyte (bulk density = mass of solid electrolyte / pellet volume).

[0155] XRD analysis was performed on the recovered sulfide-based solid electrolyte, and the results are shown in Figure 2 below.

[0156] The lattice constant of the sulfide-based solid electrolyte was calculated from the XRD pattern. The true density was calculated using the calculated lattice constant.

[0157] The apparent density (bulk density) versus true density for each sulfide-based solid electrolyte recovered in the examples and comparative examples was calculated and shown in Table 1 below.

[0158] Apparent density / true density Example 1Li 5.27 Cu 0.03 PS4O 0.3 Cl 1.7 0.89 Example 2Li 5.07 Cu 0.03 PS 3.8 O 0.3 Cl1.9 0.89Comparative example 1Li6PS5Cl0.68Comparative example 2Li 5.3 PS 4.3 Cl 1.7 0.82

[0159] Evaluation Example 3: Ionic Conductivity Measurement

[0160] The sulfide-based solid electrolytes manufactured in the Examples and Comparative Examples were formed into pellets, and then an indium (In) thin film was coated on both sides of the pellets to prepare samples for measuring ionic conductivity. The impedance of the prepared samples was measured, and a Nyquist plot was plotted, from which the ionic conductivity was measured at 25°C. The measured ionic conductivity is shown in Table 2 below.

[0161] Distinctive composition ionic conductivity Example 1Li 5.27 Cu 0.03 PS4O 0.3 Cl 1.7 2.57 Example 2Li 5.07 Cu 0.03 PS 3.8 O 0.3 Cl 1.9 2.79 Comparative Example 1Li6PS5Cl1.3 Comparative Example 2Li 5.3 PS 4.3 Cl 1.7 2.68

[0162] synthesis

[0163] In Examples 1 and 2, the apparent density (apparent density / true density) is higher than that of Comparative Examples 1 and 2, and it can be confirmed that the solid electrolyte powder is well pressed when pressed, forming a densified electrode.

[0164] Examples 1 to 2 and Comparative Example 2 showed improved ionic conductivity compared to Comparative Example 1.

[0165] Referring to Figure 1, Comparative Examples 1 and 2 showed a heat flow peak at 300°C to 400°C. In contrast, Examples 1 and 2 showed no heat flow peak up to 400°C, confirming that thermal stability was improved at high temperatures.

[0166] While exemplary embodiments have been described in detail with reference to the attached drawings, the present invention is not limited to these examples. It is self-evident that those skilled in the art to which the present invention pertains can devise various modifications or variations within the scope of the technical concepts described in the patent claims, and these also naturally fall within the technical scope of the present invention.

Claims

1. A sulfide-based solid electrolyte having an argyrodite-type crystal structure and including a compound represented by the following chemical formula 1: <Chemical Formula 1> Li 7-a-c M a PS 6-b-c O b X C In the above chemical formula 1, The above M includes Na, K, Ca, Mg, Ag, Cu, Hf, In, Ti, Pb, Sb, Fe, Zn, Cr, B, Sn, Ge, Si, Zr, Ta, Nb, V, Ga, Al, As, or a combination thereof, wherein X comprises Cl, Br, I, or a combination thereof, 0 <a≤1, 0<b≤1, 및 1.5<c≤2 이다.

2. In paragraph 1, 0 <a≤0.1, 0<b≤0.5, 및 1.65<c≤2 인 황화물계 고체 전해질.

3. In paragraph 2, Sulfide-based solid electrolyte with 2≤b+c≤3.

4. In paragraph 1, The above sulfide-based solid electrolyte is a sulfide-based solid electrolyte having a peak at 200°C to 300°C when heat flow is measured by differential scanning calorimetry (DSC).

5. In paragraph 1, The above sulfide-based solid electrolyte is a sulfide-based solid electrolyte having a maximum heat flow of 5 W / g or less when heat flow is measured using differential scanning calorimetry (DSC).

6. In paragraph 1, The above sulfide-based solid electrolyte is a sulfide-based solid electrolyte having a maximum heat flow of 3 W / g or less at a temperature of 300°C or higher when heat flow is measured by differential scanning calorimetry (DSC).

7. In paragraph 1, The above sulfide-based solid electrolyte is a sulfide-based solid electrolyte having a maximum heat flow of 1 W / g to 2 W / g at 200°C to 250°C when heat flow is measured by differential scanning calorimetry (DSC).

8. In paragraph 1, The above sulfide-based solid electrolyte is a sulfide-based solid electrolyte having a volume-based D50 particle size of 0.5 ㎛ to 6.5 ㎛ as measured by laser diffraction particle size distribution measurement.

9. In paragraph 1, The above sulfide-based solid electrolyte is a sulfide-based solid electrolyte in powder form.

10. In paragraph 1, The above sulfide-based solid electrolyte is a sulfide-based solid electrolyte in the form of a molded article.

11. In paragraph 1, The above sulfide-based solid electrolyte A sulfide-based solid electrolyte having a bulk density of 0.82 to 1 compared to a true density.

12. A cathode layer including a cathode active material layer; cathode layer; and A solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer; An all-solid-state battery, wherein at least one of the positive electrode active material layer and the solid electrolyte layer comprises a sulfide-based solid electrolyte according to claim 1.

13. In paragraph 12, The above negative electrode layer includes a negative electrode active material layer, An all-solid-state battery wherein the negative electrode active material layer comprises a carbon-based negative electrode active material including crystalline carbon, amorphous carbon, or a combination thereof.

14. In paragraph 12, The above negative electrode layer includes a negative electrode active material layer, An all-solid-state battery wherein the negative electrode active material layer includes a Si-based negative electrode active material.

15. In paragraph 12, The above cathode layer includes a cathode coating layer, An all-solid-state battery wherein the cathode coating layer comprises a metal-carbon composite.

16. In paragraph 15, The above metal-carbon composite comprises metal particles, An all-solid-state battery wherein the metal particles include at least one metal or metalloid selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn).

17. In paragraph 15, The above metal-carbon composite comprises a carbon-based material, An all-solid-state battery, wherein the carbon-based material comprises at least one selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene.

18. In paragraph 15, The above cathode layer is, negative current collector; and An all-solid-state battery further comprising a lithium metal layer disposed between the negative electrode current collector and the negative electrode coating layer.

19. In paragraph 15, The above cathode layer is, negative current collector; and An all-solid-state battery further comprising a thin film disposed between the negative electrode current collector and the negative electrode coating layer and containing an element capable of forming an alloy with lithium.

20. In paragraph 12, The above bipolar layer is, anode current collector; and An all-solid-state battery further comprising an intermediate layer disposed between the positive electrode current collector and the positive electrode active material layer, the intermediate layer including a carbon-based conductive material.

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