Positive active material for all solid state battery and all solid state battery comprising the same

Abstract

Provided are a positive electrode active material for an all-solid-state battery and an all-solid-state battery including the same, the positive electrode active material including a core including lithium metal oxide; and a surface layer disposed on at least a portion of a surface of the core and including an amorphous glass, wherein the amorphous glass includes Li, Si, B, Al, and O.

Description

[Rectified under Rule 91, 19.12.2024]POSITIVE ACTIVE MATERIAL FOR ALL SOLID STATE BATTERY AND ALL SOLID STATE BATTERY COMPRISING THE SAME

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

[0002] Recently, as portable electronic devices are required to be miniaturized and used for long periods of time, higher capacity batteries are required, and with the spread of wearable electronic devices, there is a demand to ensure the safety of batteries. Therefore, the development of all-solid-state batteries using solid electrolytes instead of liquid electrolytes is actively underway.

[0003] All-solid-state batteries do not use flammable organic solvents, so additional circuits for safety can be simplified. Therefore, it is expected to be a technology that can manufacture safe batteries with high capacity per unit volume.

[0004] Oxide all-solid-state batteries using oxide electrolytes have lower ionic conductivity of the electrolyte (10-4S / cm to 10-6S / cm) than sulfide (10-2S / cm), and require a high-temperature sintering treatment process. However, they have superior stability compared to sulfide all-solid-state batteries using sulfide electrolytes that react with oxygen and moisture in the air.

[0005] Meanwhile, the development of a stacked type all-solid-state battery capable of implementing high capacity per unit volume is also being actively researched. The stacked oxide all-solid-state battery is an ultra-small battery that can be mounted on a substrate like a passive device and is stable even when exposed to high temperatures during the reflow process.

[0006] An embodiment provides a positive electrode active material for an all-solid-state battery having improved capacity and energy density by suppressing surface damage and having excellent interfacial connectivity with a solid electrolyte.

[0007] Another embodiment provides a positive electrode layer for an all-solid-state battery including the positive electrode active material.

[0008] Another embodiment provides an all-solid-state battery including the positive electrode active material.

[0009] An embodiment provides a positive electrode active material for an all-solid-state battery, including: a core including lithium metal oxide; and a surface layer disposed on at least a portion of a surface of the core and including an amorphous glass, wherein the amorphous glass includes elements of Li, Si, B, Al, and O.

[0010] The Li element may be included in an amount of 30 atomic% to 60 atomic% based on a total amount of the amorphous glass.

[0011] The B element may be included in an amount of 10 atomic% to 50 atomic% based on a total amount of the amorphous glass.

[0012] The Si element may be included in an amount of 10 atomic% to 20 atomic% based on a total amount of the amorphous glass.

[0013] The Al element may be included in an amount of 0.1 atomic% to 10 atomic% based on a total amount of the amorphous glass.

[0014] The amorphous glass may further include one or more additional elements selected from the elements Ba, Zn, Na, Mg, K, Ca, Ti, Mn, Fe, P, and Cl.

[0015] The one or more additional elements may be included in an amount of 0.5 atomic% to 20 atomic% based on a total amount of the amorphous glass.

[0016] A thickness of the surface layer may be 0.5% to 10% of the diameter of the core.

[0017] The surface layer may be disposed in the form of an island on the surface of the core, or on the entire surface of the core.

[0018] The amorphous glass may be included in an amount of 2 parts by weight to 10 parts by weight based on 100 parts by weight of the lithium metal oxide.

[0019] Another embodiment provides a positive electrode layer for an all-solid-state battery including the positive electrode active material.

[0020] Another embodiment provides an all-solid-state battery including a positive electrode layer including a positive electrode active material; a negative electrode layer; and a solid electrolyte layer between the positive electrode layer and the negative electrode layer, wherein the positive electrode active material includes a core including lithium metal oxide; and a surface layer disposed on at least a portion of a surface of the core and including an amorphous glass, wherein the amorphous glass includes elements of Li, Si, B, Al, and O.

[0021] According to an embodiment, the positive electrode active material can suppress surface damage caused by heat treatment (sintering) in the manufacturing process of an all-solid-state battery, and when applied to an all-solid-state battery, the interfacial connectivity between the positive electrode active material and the solid electrolyte can be improved. Accordingly, an all-solid-state battery with high capacity and energy density may be secured.

[0022] FIG. 1 is an XRD graph of amorphous glass according to an embodiment.

[0023] FIG. 2 is a perspective view showing an all-solid-state battery according to an embodiment.

[0024] FIG. 3 is a cross-sectional view of the all-solid-state battery taken along line I-I' of FIG. 2.

[0025] FIG. 4 is an exploded perspective view showing the structure of the stack in the all-solid-state battery of FIG. 2.

[0026] FIG. 5 is a SEM image of the positive electrode active material according to Example 1.

[0027] FIG. 6 is a SEM image of the positive electrode active material according to Comparative Example 1.

[0028] FIG. 7 is an SEM image of the positive electrode layer according to Example 1.

[0029] FIG. 8 is a SEM image of the positive electrode layer according to Comparative Example 1.

[0030] Hereinafter, the present disclosure will be described in detail hereinafter with reference to the accompanying drawings, in which embodiments of the present disclosure are shown. The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification. In the accompanying drawings, some constituent elements are exaggerated, omitted, or schematically illustrated, and the size of each constituent element does not entirely reflect the actual size.

[0031] The accompanying drawings are intended only to facilitate an understanding of the exemplary embodiments disclosed in this specification, and it is to be understood that the technical ideas disclosed herein are not limited by the accompanying drawings and include all modifications, equivalents, or substitutions that are within the range of the ideas and technology of the present disclosure.

[0032] Although terms of "first," "second," and the like are used to explain various constituent elements, the constituent elements are not limited to such terms. These terms are only used to distinguish one constituent element from another constituent element.

[0033] It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. Further, when an element is referred to as being "on" or "above" a reference element, it can be positioned above or below the reference element, and it is not necessarily referred to as being positioned "on" or "above" in a direction opposite to gravity.

[0034] Throughout the specification, the terms "comprise" or "have" are intended to specify the presence of stated features, integers, steps, operations, constituent elements, components or a combination thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, constituent elements, components, and / or groups thereof. Therefore, unless explicitly described to the contrary, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.

[0035] In addition, the phrase "on a plane" means a view from a position above the object (e.g., from the top), and the phrase "on a cross-section" means a view of a cross-section of the object which is vertically cut from the side.

[0036] Throughout the specification, the term "connected" does not mean only that two or more constituent components are directly connected, but may also mean that two or more constituent components are indirectly connected through another constituent component, that two or more components are electrically connected as well as physically connected, or that two or more constituent components are referred to by different names but are united by location or function.

[0037] Positive Electrode Active Material

[0038] The positive electrode active material according to an embodiment may include a core including lithium metal oxide, and a surface layer on at least a portion of a surface of the core.

[0039] The surface layer may include an amorphous glass including elements of lithium (Li), silicon (Si), boron (B), aluminum (Al), and oxygen (O).

[0040] In other words, the positive electrode active material may be a material in which the surface of lithium metal oxide is surface-modified with the amorphous glass.

[0041] Carbon materials are generally used as conductive materials to provide electronic conductivity to positive electrode active materials. In the case of all-solid-state batteries, unlike lithium-ion batteries, heat treatment at over 400 °C is required, and at this time, carbon acts as a strong reducing agent and can damage the positive electrode active material, thereby deteriorating performance. In addition, in the case of all-solid-state batteries, unlike lithium-ion batteries that use liquid electrolytes, the interfacial connectivity between the positive electrode active material and the solid electrolyte is very poor, which may result in deterioration in product performance.

[0042] According to an embodiment, a positive electrode active material, that is, a positive electrode active material having a surface layer including an amorphous glass disposed on at least a portion of a surface of a core including lithium metal oxide, may suppress surface damage of the positive electrode active material due to heat treatment during a sintering process of a stack during the manufacture of an all-solid-state battery. In addition, the interfacial connectivity between the positive electrode active material and the solid electrolyte is improved, so that an all-solid-state battery with high capacity and energy density can be secured.

[0043] The amorphous glass may be explained with reference to FIG. 1.

[0044] FIG. 1 is an XRD (X-ray diffraction analysis) graph for amorphous glass according to an embodiment.

[0045] The amorphous glass is a non-crystalline or amorphous solid that does not exhibit evidence of long-range structural order when analyzed by X-ray diffraction, as shown in FIG. 1.

[0046] The lithium (Li) element included in the amorphous glass may be included in an amount of 30 atomic% to 60 atomic%, for example, 33 atomic% to 57 atomic%, 35 atomic% to 55 atomic%, 38 atomic% to 52 atomic%, or 40 atomic% to 50 atomic% based on the total amount of the amorphous glass. When the content of Li element is within the above range, damage to the surface of the positive electrode active material can be suppressed even after the sintering of the stack, and also the interfacial connectivity between the positive electrode active material and the solid electrolyte can be improved. Accordingly, the capacity and energy density of the all-solid-state battery may be improved.

[0047] The boron (B) element included in the amorphous glass may be included in an amount of 10 atomic% to 50 atomic%, for example 13 atomic% to 47 atomic%, 15 atomic% to 45 atomic%, 18 atomic% to 42 atomic%, or 20 atomic% to 40 atomic% based on a total amount of the amorphous glass. When the content of the B element is within the above range, a positive electrode active material without surface damage can be obtained even after the sintering of the stack, and also the interfacial connectivity between the positive electrode active material and the solid electrolyte can be improved. Accordingly, the capacity and energy density of the all-solid-state battery may be improved.

[0048] The silicon (Si) element included in the amorphous glass may be included in an amount of 10 atomic% to 20 atomic%, for example 11 atomic% to 19 atomic%, 12 atomic% to 18 atomic%, or 13 atomic% to 17 atomic% based on a total amount of the amorphous glass. When the content of Si element is within the above range, a positive electrode active material without surface damage even after heat treatment can be obtained, and also the interfacial connectivity between the positive electrode active material and the solid electrolyte can be improved. Accordingly, the capacity and energy density of the all-solid-state battery may be improved.

[0049] The aluminum (Al) element included in the amorphous glass may be included in an amount of 0.1 atomic% to 10 atomic%, for example, 0.3 atomic% to 9 atomic%, 0.5 atomic% to 8 atomic%, 0.8 atomic% to 7 atomic%, or 1 atomic% to 6 atomic% based on a total amount of the amorphous glass. When the content of the Al element is within the above range, a positive electrode active material without surface damage even after heat treatment can be obtained, and also the interfacial connectivity between the positive electrode active material and the solid electrolyte can be improved. Accordingly, the capacity and energy density of the all-solid-state battery may be improved.

[0050] The amorphous glass may further include one or more additional elements selected from the elements of barium (Ba), zinc (Zn), sodium (Na), magnesium (Mg), potassium (K), calcium (Ca), titanium (Ti), manganese (Mn), iron (Fe), phosphorus (P), and chlorine (Cl).

[0051] The one or more additional elements may be included in an amount of 0.5 atomic% to 20 atomic%, for example 0.7 atomic% to 17 atomic%, 1.0 atomic% to 15 atomic%, 1.3 atomic% to 12 atomic%, or 1.5 atomic% to 10 atomic% based on the total amount of the amorphous glass. When the content of the above additional element is within the above range, a positive electrode active material without surface damage even after heat treatment can be obtained, and also the interfacial connectivity between the positive electrode active material and the solid electrolyte can be improved. Accordingly, the capacity and energy density of the all-solid-state battery may be improved.

[0052] The structure and components of a positive electrode active material according to an embodiment, specifically, a positive electrode active material in which an amorphous glass including elements of Li, Si, B, Al, and O is disposed on the surface of a lithium metal oxide, may be confirmed by scanning electron microscope (SEM) analysis and inductively coupled plasma-optical emission spectrometry (ICP-OES) analysis.

[0053] Specifically, SEM analysis may be performed on a cross-sectional sample of the positive electrode active material using a high-resolution scanning electron microscope (HR-SEM) at a condition of 10 kV in an area of about 26 μm X 26 μm. Meanwhile, a cross-sectional sample may be obtained by breaking a chip of an all-solid-state battery 100 and then separating an area where at least one positive electrode layer is visible at a location close to the external electrode of the positive electrode within the stack 110.

[0054] Additionally, component analysis can be performed by dissolving the positive electrode active material in nitric acid, then diluting it and detecting the components using ICP-OES.

[0055] The thickness of the surface layer may be 0.5% to 10%, for example 0.7% to 9%, 1% to 8%, 1.2% to 7%, 1.5% to 6%, or 2% to 5% of the diameter of the core. At this time, the core diameter refers to a diameter based on the major axis of the core. When the thickness of the surface layer is within the above range, damage to the surface of the positive electrode active material can be suppressed even after the sintering of the stack, and also the interfacial connectivity between the positive electrode active material and the solid electrolyte can be improved. Accordingly, the capacity and energy density of the all-solid-state battery may be improved.

[0056] The thickness of the surface layer can be confirmed by scanning electron microscope (SEM) analysis. Specifically, SEM analysis can be performed on a cross-sectional sample obtained by the above-described method using a high-resolution scanning electron microscope (HR-SEM) at a condition of 10 kV in an area of about 12 μm X 12 μm. In the SEM image of the cross-sectional sample above, one random point is selected for each particle for 10 particles of adjacent positive electrode active materials, and the arithmetic mean value of the thickness of the surface layer at the 10 points can be obtained.

[0057] The surface layer may be disposed in the form of an island on the surface of the core, or may be disposed on the entire surface of the core.

[0058] The amorphous glass may be included in an amount of 2 parts by weight to 10 parts by weight, for example 3 parts by weight to 9 parts by weight, 4 parts by weight to 8 parts by weight, or 5 parts by weight to 7 parts by weight, based on 100 parts by weight of the lithium metal oxide. When the content of amorphous glass is within the above range, a positive electrode active material without surface damage even after heat treatment can be obtained, and also the interfacial connectivity between the positive electrode active material and the solid electrolyte can be improved. Therefore, an all-solid-state battery with high capacity and energy density may be secured.

[0059] The lithium metal oxide may include lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium manganese oxide, or a combination thereof.

[0060] The positive electrode active material may be, for example, a compound represented by the following chemical formulas:

[0061] LiaAl-bMbD2(where 0.90≤a≤1.8, 0≤b≤0.5); LiaEl-bMbO2-cDc(where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiE2-bMbO4-cDc(where 0≤b≤0.5, 0≤c≤0.05); LiaNi1-b-cCobMcDα(where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); LiaNi1-b-cCobMcO2-αXα(where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); LiaNi1-b-cCObMcO2-αX2(where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); LiaNi1-b-cMnbMcDα(where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); LiaNi1-b-cMnbMcO2-αXα(where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); LiaNi1-b-cMnbMcO2-αX2(where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); LiaNibEcGdO2(where 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1); LiaNibCocMndGeO2(where 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1); LiaNiGbO2(where 0.90≤a≤1.8, 0.001≤b≤0.1); LiaCoGbO2(where 0.90≤a≤1.8, 0.001≤b≤0.1); LiaMnGbO2(where 0.90≤a≤1.8, 0.001≤b≤0.1); LiaMn2GbO4(where 0.90≤a≤1.8, 0.001≤b≤0.1); QO2; QS2; LiQS2; V2O5; LiV2O2; LiRO2; LiNiVO4; Li(3-f)J2PO43(0≤f≤2); Li(3-f)Fe2PO43(where 0≤f≤2); and LiFePO4. In the above formula, A is Ni, Co, or Mn; M is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, or a rare-earth element; D is O, F, S, or P; E is Co or Mn; X is F, S, or P; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, or V; Q is Ti, Mo or Mn; R is Cr, V, Fe, Sc, or Y; and J is V, Cr, Mn, Co, Ni, or Cu.

[0062] The lithium metal oxide may also be LiCoO2, LiMnxO2x(where x=1 or 2), LiNi1-xMnxO2x(where 0<x<1), LiNi1-x-yCoxMnyO2(where 0≤x≤0.5, 0≤y≤0.5), LiFePO4, TiS2, FeS2, TiS3, or FeS3.

[0063] According to an embodiment, a positive electrode active material can be manufactured by mixing a lithium metal oxide and an amorphous glass composition using a mechanofusion method or a ball impaction method, and dry-coating the amorphous glass on the surface of the lithium metal oxide.

[0064] Mechanofusion method may be performed using a mechanofusion device (Hosokawa Micron, AMS-LAB). The mechanofusion method may be performed under conditions of a rotor speed of 100 rpm to 2500 rpm and a jacket temperature of 40 °C to 60 °C.

[0065] The amorphous glass composition may include lithium oxide (Li2O), boron trioxide (B2O3), silicon dioxide (SiO2), and aluminum oxide (Al2O3).

[0066] The amorphous glass composition may further include one or more selected from barium oxide (BaO), zinc oxide (ZnO), sodium oxide (Na2O), magnesium oxide (MgO), potassium oxide (K2O), calcium oxide (CaO), titanium oxide (TiO2), manganese dioxide (MnO2), iron oxide (Fe2O3), phosphoric acid (P2O3), and chloric acid (HClO3).

[0067] The amorphous glass composition may be mixed in an amount of 2 parts by weight to 10 parts by weight, for example 3 parts by weight to 9 parts by weight, 4 parts by weight to 8 parts by weight, or 5 parts by weight to 7 parts by weight, based on 100 parts by weight of the lithium metal oxide. When mixed within the above range, a positive electrode active material without surface damage can be obtained even after sintering of the stack during the manufacture of an all-solid-state battery, and the interfacial connectivity between the positive electrode active material and the solid electrolyte can also be improved. Therefore, an all-solid-state battery with high capacity and energy density may be secured.

[0068] All-solid-state Battery

[0069] Hereinafter, an all-solid-state battery including the aforementioned positive electrode active material will be described with reference to FIGS. 2 to 4.

[0070] FIG. 2 is a perspective view showing an all-solid-state battery according to an embodiment, FIG. 3 is a cross-sectional view of the all-solid-state battery taken along line I-I' of FIG. 2, and FIG. 4 is an exploded perspective view showing the structure of a stack in the all-solid-state battery of FIG. 2.

[0071] The L-axis, W-axis, and T-axis shown in FIGS. 2 to 4 represent the length direction, width direction, and thickness direction of the stack 110 of the all-solid-state battery, respectively. Here, the thickness direction (T-axis direction) may be a direction perpendicular to a wide surface (main surface) of the constituent elements in a sheet shape, and may for example be used as a same concept as the stacking direction in which the unit cells are stacked. The length direction (L-axis direction) may be a direction that extends parallel to a broad surface (main surface) of the constituent elements in the sheet shape and may be a direction approximately perpendicular to the thickness direction (T-axis direction), for example, it may be the direction in which the first external electrode 112 and the second external electrode 114 are disposed on respective sides. The width direction (W-axis direction) may be a direction that extends parallel to the broad surface (main surface) of the constituent elements in the sheet shape and may be a direction that is approximately perpendicular to the thickness direction (T-axis direction) and the length direction (L-axis direction), and the length of the constituent elements in the sheet shape in the length direction (L-axis direction) may be greater than the length in the width direction (W-axis direction).

[0072] Referring to FIGS. 2 to 4, an all-solid-state battery 100 according to an embodiment includes a stack 110 and external electrodes 112 and 114 disposed on the outside of the stack 110. The external electrodes 112 and 114 may include a first external electrode 112 and a second external electrode 114 disposed at opposite ends in the length direction (L-axis direction) of the stack 110.

[0073] For better understanding and ease of description of an embodiment, in the stack 110 of the all-solid-state battery, respective sides facing each other in the thickness direction (T-axis direction) will be defined to be a first side and a second side, respective sides connected to the first side and the second side and facing each other in the length direction (L-axis direction) will be defined to be a third side and a fourth side, and respective sides connected to the first and second sides, connected to the third and fourth sides, and facing each other in the width direction (W axis direction) will be defined to be a fifth side and a sixth side.

[0074] For example, the first side, which is a lower surface, may be the side facing a mounting direction. Additionally, the first to sixth sides may be flat, and the embodiment is not limited thereto. For example, the first to sixth sides may be curved surfaces of which central portions are convex, and edges that are boundaries of the respective sides may be round.

[0075] The stack 110 of the all-solid-state battery may have, for example, a roughly hexahedral shape.

[0076] The shape, dimensions, and number of stacked unit cells of the stack 110 of the all-solid-state battery are not limited to those shown in the drawings of the present embodiment.

[0077] A stack 110 of an all-solid-state battery 100 according to an embodiment includes a positive electrode layer 120, a negative electrode layer 140, and a solid electrolyte layer 130 disposed between the positive electrode layer 120 and the negative electrode layer 140 in the stacking direction.

[0078] For example, the electrode layer disposed at the top of the stack 110 based on the stacking direction may be a positive electrode layer 120 or a negative electrode layer 140, and the electrode layer disposed at the bottom of the stack 110 may correspondingly be a negative electrode layer 140 or a positive electrode layer 120.

[0079] The positive electrode layer 120 may include a positive electrode current collector 123 and positive electrode active material layers 121 and 122 disposed on at least one surface of the positive electrode current collector 123. Specifically, the positive electrode active material layers 121 and 122 may include a first positive electrode active material layer 121 disposed on one surface of the positive electrode current collector 123 and a second positive electrode active material layer 122 disposed on the other surface of the positive electrode current collector 123. For example, when the positive electrode layer 120 is disposed at the top of the stack 110 based on the stacking direction, the positive electrode layer 120 may have a structure in which a second positive electrode active material layer 122 is disposed on one surface of the positive electrode current collector 123. In addition, the positive electrode layer 120 disposed between the uppermost and lowermost layers of the stack 110 may have a structure in which a first positive electrode active material layer 121 and a second positive electrode active material layer 122 are disposed on each of both surfaces of the positive electrode current collector 123.

[0080] The positive electrode current collector 123 may be formed of, for example, a plate-shaped member or a thin member. As another example, the positive electrode current collector 123 may be a porous body, such as a reticulate or mesh shape.

[0081] The positive electrode current collector 123 may be a porous metal plate made of, for example, stainless steel, nickel (Ni), copper (Cu), tin (Sn), aluminum (Al), or an alloy thereof, but is not limited thereto. Additionally, the positive electrode current collector 123 may be coated with an oxidation-resistant metal or alloy film to prevent oxidation.

[0082] The positive electrode current collector 123 may be made of a carbon-based plate-shaped, thin-walled, or linear member. Specifically, the positive electrode current collector 123 may be made of a conductive carbon material, and the conductive carbon material may be, for example, conductive fibers such as graphite, carbon nanotubes (CNTs), vapor grown carbon fibers (VGCFs), or conductive carbon such as carbon black.

[0083] The positive electrode current collector 123 may include one or more types of solid electrolytes described below.

[0084] The positive electrode active material layers 121 and 122 includes the positive electrode active material described above.

[0085] The positive electrode active material layers 121 and 122 may further include a solid electrolyte.

[0086] The solid electrolyte can function as an ion conducting channel within the anode layer. This can reduce the interfacial resistance. The solid electrolyte included in the positive electrode active material layers 121 and 122 is the same as the solid electrolyte included in the solid electrolyte layer 130 described later, and thus its description is omitted here.

[0087] The positive electrode active material layers 121 and 122 may further include one or more selected from a conductive material and a binder.

[0088] The conductive material is not particularly limited as long as it has conductivity and does not cause chemical changes in the all-solid-state battery 100. For example, graphite, such as natural graphite or artificial graphite; a carbon-based material such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; a conductive fiber such as carbon fiber and metal fiber; carbon fluoride; a metal powder such as aluminum and nickel powder; a conductive whisker such as zinc oxide and potassium titanate; a conductive metal oxide such as titanium oxide; or a conductive material such as polyphenylene derivative may be used.

[0089] The conductive material may be included in an amount of 1 part by weight to 10 parts by weight, for example 5 parts by weight to 10 parts by weight, based on 100 parts by weight of the positive electrode active material. When the content of the conductive material is within the above range, a positive electrode layer having excellent conductivity characteristics may be obtained.

[0090] A binder can be used to improve the binding strength between positive active materials and conductive materials. The binder may include acrylic, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, an ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, a styrene butadiene rubber, a fluorine rubber, and various copolymers.

[0091] The binder may be included in an amount of 1 part by weight to 50 parts by weight, for example 1 part by weight to 30 parts by weight, based on 100 parts by weight of the positive electrode active material. When the binder content is within the above range, the positive electrode active material layer can have high binding strength.

[0092] The positive electrode active material layers 121 and 122 can be formed by printing the positive electrode active material on one or both surfaces of the positive electrode current collector 123, but the method of forming the positive electrode active material layer is not limited thereto.

[0093] A thickness of the positive electrode layer 120 may be 5 μm to 25 μm, for example, 10 μm to 20 μm.

[0094] The negative electrode layer 140 may include a negative electrode current collector 143 and a negative electrode active material layers 141 and 142 disposed on at least one surface of the negative electrode current collector 143. Specifically, the negative electrode active material layers 141 and 142 may include a first negative electrode active material layer 141 disposed on one surface of the negative electrode current collector 143 and a second negative electrode active material layer 142 disposed on the other surface of the negative electrode current collector 143. For example, when the negative electrode layer 140 is disposed at the bottom of the stack 110 based on the stacking direction, the negative electrode layer 140 may have a structure in which the first negative electrode active material layer 141 is disposed on one surface of the negative electrode current collector 143. In addition, the negative electrode layer 140 disposed between the uppermost and lowermost layers of the stack 110 may have a structure in which a first negative electrode active material layer 141 and a second negative electrode active material layer 142 are disposed on each of both surfaces of the negative electrode current collector 143.

[0095] The negative electrode current collector 143 may be formed of, for example, a plate-shaped member or a thin member. As another example, the negative electrode current collector 143 may be a porous body, such as a reticulate or mesh shape.

[0096] The negative electrode current collector 143 may be a porous metal plate made of, for example, stainless steel, nickel (Ni), copper (Cu), tin (Sn), aluminum (Al), or an alloy thereof, but is not limited thereto. Additionally, the negative electrode current collector 143 may be coated with an oxidation-resistant metal or alloy film to prevent oxidation.

[0097] The negative electrode current collector 143 may be made of a conductive carbon-based material similar to the positive electrode current collector 123 and may include one or more solid electrolytes. The negative electrode current collector 143 may be identical to the negative electrode active material layers 141 and 142.

[0098] The negative electrode active material layers 141 and 142 includes a negative electrode active material.

[0099] The negative electrode active material may store lithium ions that have moved from the positive electrode layer and release them when the all-solid-state battery is discharged, thereby generating electrical energy.

[0100] The negative electrode active material may include a carbon-based material, silicon, silicon oxide, a silicon-based alloy, a silicon-carbon-based material composite, tin, a tin-based alloy, a tin-carbon composite, metal oxide, or a combination thereof, and may include a lithium metal and / or a lithium metal alloy.

[0101] The lithium metal alloy may include lithium and metal / metalloid capable of alloying with lithium. For example, the metal / metalloid capable of alloying with lithium may be Si, Sn, Al, Ge, Pb, Bi, Sb, Si-M1 alloy (where M1 is an alkali metal, alkaline earth metal, Group 13 to 16 elements, transition metal, rare earth element, or a combination thereof, but does not include Si), an Sn-M2 alloy (where M2 is an alkali metal, alkaline earth metal, Group 13 to 16 elements, a transition metal, transition metal oxide of lithium titanium oxide (Li4Ti5O12), etc., a rare earth element or a combination element thereof, and does not include Sn), MnOx(0<x≤2), etc.

[0102] The elements M1 and M2 may each independently be Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof.

[0103] Further, the oxide of the metal / metalloid capable of alloying with lithium may be lithium titanium oxide, vanadium oxide, lithium vanadium oxide, SnO2, SiOx(0<x<2), or the like. For example, the negative electrode active material may include one or more elements selected from Group 13 to 16 elements of the Periodic Table of Elements. For example, the negative electrode active material may include one or more elements selected from the group consisting of Si, Ge, and Sn.

[0104] The carbon-based material may be crystalline carbon, amorphous carbon, or a mixture thereof. The crystalline carbon may be graphite such as amorphous, plate-like, flake-like, spherical or fibrous natural graphite or artificial graphite. In addition, the amorphous carbon may include soft carbon (low temperature calcined carbon) or hard carbon, a mesophase pitch carbonization product, calcined coke, graphene, carbon black, fullerene soot, carbon nanotubes, carbon fiber, and the like.

[0105] The silicon may be Si, SiOx(0<x<2, for example 0.5 to 1.5), Sn, SnO2, a silicon-containing metal alloy, or a mixture thereof. The silicon-containing metal alloy may include, for example, silicon and one or more of Al, Sn, Ag, Fe, Bi, Mg, Zn, In, Ge, Pb, and Ti.

[0106] The negative electrode active material layers 141 and 142 may further include a solid electrolyte.

[0107] The solid electrolyte can function as an ion conducting channel within the negative electrode layer. This can reduce the interfacial resistance. The solid electrolyte included in the negative electrode active material layers 141 and 142 is the same as the solid electrolyte included in the solid electrolyte layer 130 described later, so its description is omitted here.

[0108] The negative electrode active material layers 141 and 142 may further include one or more selected from a conductive material and a binder.

[0109] The conductive material is not particularly limited as long as it has conductivity without causing chemical change in the all-solid-state battery 100. For example, examples of the conductive material may include: graphite such as natural graphite and artificial graphite; carbon-based substances such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers such as carbon fibers and metal fibers; fluorinated carbon; metal powders such as aluminum and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive materials such as polyphenylene derivatives.

[0110] The conductive material may be included in an amount of 1 part by weight to 10 parts by weight, for example 5 parts by weight to 10 parts by weight based on 100 parts by weight of the negative electrode active material. When the content of the conductive agent is within the above range, a negative electrode layer having excellent conductivity characteristics can be obtained.

[0111] A binder can be used to improve the binding strength between negative active materials and conductive materials. The binder may include acrylic, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, an ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, a styrene butadiene rubber, a fluorine rubber, and various copolymers.

[0112] The binder may be included in an amount of 1 part by weight to 50 parts by weight, for example, 1 part by weight to 30 parts by weight, based on 100 parts by weight of the negative active material. When the binder content is within the above range, the negative electrode active material layer can have high binding strength.

[0113] The negative electrode active material layers 141 and 142 can be formed by printing the negative electrode active material on one side or both surfaces of the negative electrode current collector 143, but the method of forming the negative electrode active material layer is not limited thereto.

[0114] A thickness of the negative electrode layer 140 may be 4 μm to 15 μm, for example 5 μm to 12 μm.

[0115] The solid electrolyte layer 130 may be interposed and stacked between the positive electrode layer 120 and the negative electrode layer 140. Specifically, the solid electrolyte layer 130 may be adjacently disposed between the positive electrode active material layers 121 and 122 of the positive electrode layer 120 and the negative electrode active material layers 141 and 142 of the negative electrode layer 140 in the stacking direction. In other words, within the all-solid-state battery 100, specifically, within the stack 110 of the all-solid-state battery 100, a plurality of positive electrode layers 120 and negative electrode layers 140 may be alternately disposed, and a plurality of solid electrolyte layers 130 may be interposed and stacked between them.

[0116] The solid electrolyte layer 130 includes a solid electrolyte. The solid electrolyte may act as a channel for lithium (Li) ions.

[0117] The solid electrolyte included in the solid electrolyte layer 130 may include a glass-ceramic electrolyte or a lithium borosilicate electrolyte.

[0118] The glass-ceramic electrolyte may include lithium halide (such as LiX, X=F, Br, Cl, I, etc.). The glass-ceramic or crystallized glass means a material in which amorphous and crystalline phases coexist, as shown by peaks and halos in X-ray diffraction or electron diffraction. Therefore, the glass-ceramic electrolyte is an electrolyte in a mixed state of amorphous and crystalline phases, with some crystallization occurring through sintering.

[0119] The glass-ceramic electrolytes may include amorphous and two or more crystalline phases. Additionally, the crystalline phases included in the glass-ceramic electrolyte may include a lithium compound crystal phase including lithium.

[0120] When the solid electrolyte includes a glass-ceramic electrolyte, sufficient densification is achieved after sintering, enabling implementation of high ionic conductivity.

[0121] The glass-ceramic electrolyte may include at least one selected from lithium (Li) oxide, boron (B) oxide, silicon (Si) oxide, aluminum (Al) oxide, gallium (Ga) oxide, phosphorus (P) oxide, germanium (Ge) oxide, magnesium (Mg) oxide, and lithium chloride (LiCl). For example, the glass-ceramic electrolyte may include Li2O, B2O3, SiO2, P2O5, GeO2, and LiCl. For example, the glass-ceramic electrolyte may be Li4B4Al3O12Cl (LCBA).

[0122] The lithium borosilicate-based electrolyte (hereinafter referred to as LBSO-based electrolyte) is a glass-like electrolyte. The glass means crystallographically amorphous, as evidenced by the observation of a halo in X-ray diffraction or electron diffraction.

[0123] When the solid electrolyte includes an LBSO-based electrolyte, the sintering temperature can be lowered while maintaining an amorphous state during sintering, thereby realizing high ionic conductivity, and there is an advantage of low reactivity with the electrode.

[0124] For example, the LBSO-based electrolyte may include lithium (Li), boron (B), silicon (Si), aluminum (Al), phosphorus (P), germanium (Ge), and sulfur (S).

[0125] Additionally, the solid electrolyte included in the solid electrolyte layer 130 may include an oxide-based solid electrolyte, a sulfide-based solid electrolyte, or a combination thereof.

[0126] The oxide-based solid electrolyte may be at least one selected from a garnet-type, nasicon-type, LISICON-type, perovskite-type, LiPON-type, and amorphous (glass) solid electrolyte.

[0127] The garnet-type solid electrolytes may indicate lithium-lanthanum zirconium oxide (LLZO) represented by LiaLabZrcO12, such as Li7La3Zr2O12. The nasicon-type solid electrolyte may indicate lithium-aluminum-titanium-phosphate (LATP) represented by Li1+xAlxTi2-x(PO4)3(0<x<1) in which Ti is introduced into a Li1+xAlxM2-x(PO4)3(LAMP) (0<x<2, wherein M is Zr, Ti, or Ge)-type compound, lithium-aluminum-germanium-phosphate (LAGP) represented by Li1+xAlxGe2-x(PO4)3(0<x<1), such as Li1.3Al0.3Ti1.7(PO4)3or the likein which excess lithium is introduced, and / or lithium-zirconium-phosphate (LZP) of LiZr2(PO4)3.

[0128] In addition, the LISICON-type solid electrolyte may indicate a solid solution oxide represented by xLi3AO4-(1-x)Li4BO4(A: P, As, V, etc., B: Si, Ge, Ti, etc.) and including Li4Zn(GeO4)4, Li10GeP2O12(LGPO), Li3.5Si0.5P0.5O4, Li10.42Si(Ge)1.5P1.5Cl0.08O11.92, etc., and solid solution sulfide including Li2S-P2S5, Li2S-SiS2, Li2S-SiS2-P2S5, or Li2S-GeS2,etc.represented byLi4-xM1-yM'yS4(M: Si, Ge, and M': P, Al, Zn, or Ga).

[0129] The perovskite-type solid electrolyte may indicate lithium-lanthanum-titanium-oxide (LLTO) represented by Li3xLa2 / 3-x□1 / 3-2xTiO3(0<x<0.16, □: vacancy), such as Li1 / 8La5 / 8TiO3or the like, and the LiPON-type solid electrolyte may refer to a nitride such as lithium-phosphorous-oxynitride, such as Li2.8PO3.3N0.46orthe like.

[0130] The amorphous solid electrolyte may be Li2O-B2O3-SiO2, Li2O-B2O3-P2O5, Li3BO3-Li2SO4, or Li3BO3-Li2CO3.

[0131] The sulfide-based solid electrolyte includes sulfur atoms among the electrolyte components and is not particularly limited to specific components, and may include one or more of a crystalline solid electrolyte, an amorphous solid electrolyte (glassy solid electrolyte), and a glass ceramic solid electrolyte.

[0132] For example, the sulfide-based solid electrolyte may include LPS-type sulfides including sulfur and phosphorus (for example, Li2S-P2S5), and Thio-LISICON type compounds, such as Li4-xGe1-xPxS4 (where x may be 0.1 to 2, 3 / 4, or 2 / 3), Li10±1MP2X12(where M is Ge, Si, Sn, or Al, and X is S, or Se), Li3.833Sn0.833As0.166S4, Li4SnS4, Li3.25Ge0.25P0.75S4, Li2S-P2S5, B2S3-Li2S, xLi2S-(100-x)P2S5(where x is 70 to 80), Li2S-SiS2-Li3N, Li2S-P2S5-LiI, Li2S-SiS2-LiI, Li2S-B2S3-LiI, Li10SnP2S12, and Li3.25Ge0.25P0.75S4.

[0133] The ionic conductivity of the solid electrolyte may be greater than or equal to 1X10-6S / cm. The ionic conductivity may be a value measured at a temperature of 25 °C. The ionic conductivity may be greater than or equal to 1X10-6S / cm, greater than or equal to 2X10-6S / cm, greater than or equal to 3X10-6S / cm, greater than or equal to 4X10-6S / cm, greater than or equal to 5X10-6S / cm, or greater than or equal to 1X10-3S / cm, and the upper limit is not particularly limited. When a solid electrolyte that satisfies the ionic conductivity in the above range is used, the all-solid-state battery 100 can exhibit high output.

[0134] The thickness of the solid electrolyte layer 130 may be 5 μm to 15 μm, for example 6 μm to 12 μm.

[0135] The stack 110 according to an embodiment may further include a margin insulating layer 150.

[0136] The margin insulating layer 150 fills the area on the solid electrolyte layer 130 excluding the area where the positive electrode layer 120 or the negative electrode layer 140 is disposed. When the positive electrode layer 120 is disposed on the solid electrolyte layer 130, a margin insulating layer 150 may be disposed in an area other than the area where the positive electrode layer 120 is disposed. Similarly, when a negative electrode layer 140 is disposed on a solid electrolyte layer 130, a margin insulating layer 150 may be disposed in an area other than the area where the negative electrode layer 140 is disposed. The margin insulating layer 150 may be disposed in the same layer of the positive electrode layer 120 and the negative electrode layer 140.

[0137] The margin insulating layer 150 can eliminate the step between the solid electrolyte layer 130 and the positive electrode layer 120 or the step between the solid electrolyte layer 130 and the negative electrode layer 140. Accordingly, the density between the solid electrolyte layer 130 and the electrode layer is increased, so that delamination or warping due to sintering can be prevented during the manufacturing process of the all-solid-state battery.

[0138] The margin insulating layer 150 may include an insulating material having an ionic conductivity of less than or equal to 1.0X10-10S / cm, or less than or equal to 1.0X10-6S / cm, and for example, insulating materials such as the aforementioned solid electrolyte material or resin may be included.

[0139] For example, the insulating material may be polyolefin such as polyethylene or polypropylene; polyester such as polyethylene terephthalate (PET); polyurethane; or polyimide.

[0140] Additionally, the margin insulating layer 150 may include a ceramic material, such as, but not limited to, alumina (Al2O3), aluminum nitride (AlN), beryllium oxide (BeO), boron nitride (BN), silicon (Si), silicon carbide (SiC), silica (SiO2), silicon nitride (Si3N4), gallium arsenide (GaAs), gallium nitride (GaN), barium titanate (BaTiO3), zirconium dioxide (ZrO2), a mixture thereof, an oxide and / or a nitride of these materials, or any other suitable ceramic material.

[0141] Additionally, the margin insulating layer 150 may include the same solid electrolyte as the solid electrolyte included in the solid electrolyte layer 130 described above, but is not limited thereto.

[0142] Additionally, the stack 110 according to an embodiment may further include a protective layer disposed as an outermost layer on the top and bottom of the stack.

[0143] The protective layer may improve moisture resistance reliability by preventing moisture penetration and prevent damage caused by physical and chemical impacts.

[0144] The protective layer may be made of an insulating material that is not electrically conductive. For example, the protective layer may include a ceramic material, such as but not limited to alumina (Al2O3), aluminum nitride (AlN), beryllium oxide (BeO), boron nitride (BN), silicon (Si), silicon carbide (SiC), silica (SiO2), silicon nitride (Si3N4), gallium arsenide (GaAs), gallium nitride (GaN), barium titanate (BaTiO3), zirconium dioxide (ZrO2), a mixture thereof, an oxide and / or a nitride of such materials, or any other suitable ceramic material.

[0145] Additionally, the protective layer may include, but is not limited to, the same solid electrolyte as the solid electrolyte included in the aforementioned solid electrolyte layer 130.

[0146] An all-solid-state battery 100 may be manufactured by alternately stacking a plurality of positive electrode layers 120 and negative electrode layers 140, interposing a plurality of solid electrolyte layers 130 between them to manufacture a stack 110, and then calcining and then pressurizing / sintering the stack 110.

[0147] The calcining may be performed at a temperature of 350 °C to 400 °C and in an air or nitrogen atmosphere. The sintering may be performed at a temperature of 400 °C to 600 °C and in an air or nitrogen atmosphere.

[0148] The external electrodes 112 and 114 are placed on the outside of the stack 110.

[0149] On both sides of the stack 110 of the all-solid-state battery 100, the terminals of the positive electrode current collector 123 and the terminals of the negative electrode current collector 143 are exposed, and external electrodes 112 and 114 can be connected and coupled to the exposed terminals.

[0150] The external electrodes 112 and 114 may be configured to be connected to the terminal of the positive electrode current collector 123 to have a positive electrode, and to be connected to the terminal of the negative electrode current collector 143 to have a negative electrode. If the terminals of the positive electrode current collector 123 and the terminals of the negative electrode current collector 143 are configured to face opposite directions, the external electrodes 112 and 114 may also be disposed on both sides, respectively.

[0151] The external electrodes 112 and 114 may include conductive metal and glass.

[0152] The conductive metal may be a conductive metal including, for example, copper (Cu), nickel (Ni), tin (Sn), palladium (Pd), platinum (Pt), gold (Au), silver (Ag), tungsten (W), titanium (Ti), lead (Pb) and alloys thereof.

[0153] A glass included in the first and second external electrodes 112 and 114 may have a composition in which an oxide is mixed. The glass may include, for example, a silicon oxide, a boron oxide, an aluminum oxide, a transition metal oxide, an alkali metal oxide, an alkaline-earth metal oxide, or a combination thereof. Here, the transition metal may be at least one selected from zinc (Zn), titanium (Ti), copper (Cu), vanadium (V), manganese (Mn), iron (Fe), and nickel (Ni), the alkali metal may be at least one selected from lithium (Li), sodium (Na), and potassium (K), and the alkaline earth metal may be at least one selected from magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba).

[0154] The method of forming the external electrodes 112 and 114 is not particularly limited. For example, the stack 110 may be formed by dipping it into a conductive paste containing a conductive metal and glass, or by printing the conductive paste on the surface of the stack 110 using a screen printing method or a gravure printing method. In addition, external electrodes can be formed in various ways, such as by coating conductive paste on the surface of the stack 110 or by transferring a dried film of conductive paste to the stack 110.

[0155]

[0156] Hereinafter, the embodiments are illustrated in more detail with reference to examples. However, these examples are exemplary, and the present scope is not limited thereto.

[0157] (Manufacturing of All-solid-state Battery)

[0158] Example 1

[0159] LiCoO2and an amorphous glass composition were added to a mechanofusion device (AMS-LAB, Hosokawa Micron Ltd.) and dry-coated under the conditions of a rotor speed of 2000 rpm and a jacket temperature of 50 °C to prepare a positive electrode active material in which amorphous glass was coated on the surface of lithium metal oxide. Herein, the amorphous glass composition consisted of 50 atomic% of Li2O, 33 atomic% of B2O3, 16 atomic% of SiO2, and 1 atomic% of Al2O3and mixed in an amount of 5 parts by weight based on 100 parts by weight of LiCoO2.

[0160] The prepared positive electrode active material, Li4B4Al3O12Cl (LCBA), carbon black (Li100), and an acryl binder were mixed, and the mixture was printed on a carbon current collector to form a positive electrode layer green sheet. Herein, the positive electrode active material and LCBA were mixed in a weight ratio of 1:1, and the carbon black and the acryl binder were mixed in each amount of 10 parts by weight and 30 parts by weight based on 100 parts by weight of a total amount of the positive electrode active material and LCBA.

[0161] In addition, a negative electrode layer green sheet was formed by using artificial graphite, Li4B4Al3O12Cl (LCBA), and an acryl binder. Herein, the artificial graphite and LCBA were mixed in a weight ratio of 1:1, and the acryl binder was mixed in an amount of 30 parts by weight based on 100 parts by weight of a total amount of the artificial graphite and LCBA.

[0162] In addition, a solid electrolyte layer green sheet was formed by using Li4B4Al3O12Cl (LCBA).

[0163] The formed positive electrode layer green sheet, solid electrolyte layer green sheet, and negative electrode layer green sheet were stacked to from a stack, calcinated at 400 °C under an air or nitrogen atmosphere, and pressurized / sintered at 500 °C under the air or nitrogen atmosphere, manufacturing an all-solid-state battery cell. In the manufactured all-solid-state battery cell, the positive electrode layer had a thickness of about 18 μm, the negative electrode layer had a thickness of about 10 μm, and the solid electrolyte layer had a thickness of about 10 μm.

[0164] Example 2

[0165] An all-solid-state battery cell was manufactured in the same manner as in Example 1 except that the positive electrode active material was prepared by using LiNi0.8Co0.1Mn0.1O2(NCM811) instead of LiCoO2.

[0166] Example 3

[0167] An all-solid-state battery cell was manufactured in the same manner as in Example 1 except that the positive electrode active material was prepared by using LiFePO4instead of LiCoO2.

[0168] Comparative Example 1

[0169] An all-solid-state battery cell was manufactured in the same manner as in Example 1 except that the positive electrode active material was prepared by using LiCoO2but not using the amorphous glass composition.

[0170] Comparative Example 2

[0171] An all-solid-state battery cell was manufactured in the same manner as in Example 1 except that the positive electrode active material was prepared by using an amorphous glass composition consisting of 70 atomic% of Li2O and 30 atomic% of SiO2.

[0172] Comparative Example 3

[0173] An all-solid-state battery cell was manufactured in the same manner as in Example 1 except that the positive electrode active material was prepared by using an amorphous glass composition consisting of 69 atomic% of Li2O, 30 atomic% of SiO2, and 1 atomic% of Al2O3.

[0174] Comparative Example 4

[0175] An all-solid-state battery cell was manufactured in the same manner as in Example 2 except that the amorphous glass composition was not used, but LiNi0.8Co0.1Mn0.1O2(NCM811) was used as the positive electrode active material.

[0176] Comparative Example 5

[0177] An all-solid-state battery cell was manufactured in the same manner as in Example 2 except that the positive electrode active material was prepared by using an amorphous glass composition consisting of 70 atomic% of Li2O and 30 atomic% of SiO2.

[0178] Comparative Example 6

[0179] An all-solid-state battery cell was manufactured in the same manner as in Example 2 except that the positive electrode active material was prepared by using an amorphous glass composition consisting of 69 atomic% of Li2O, 30 atomic% of SiO2, and 1 atomic% of Al2O3.

[0180] Comparative Example 7

[0181] An all-solid-state battery cell was manufactured in the same manner as in Example 3 except that the amorphous glass composition was not used, but LiFePO4was used as the positive electrode active material.

[0182] Comparative Example 8

[0183] An all-solid-state battery cell was manufactured in the same manner as in Example 3 except that the positive electrode active material was prepared by using an amorphous glass composition consisting of 70 atomic% of Li2O and 30 atomic% of SiO2.

[0184] Comparative Example 9

[0185] An all-solid-state battery cell was manufactured in the same manner as in Example 3 except that the positive electrode active material was prepared by using an amorphous glass composition consisting of 69 atomic% of Li2O, 30 atomic% of SiO2, and 1 atomic% of Al2O3.

[0186] Evaluation 1: SEM Analysis

[0187] The all-solid-state battery cells according to Example 1 and Comparative Example 1 were subjected to a scanning electron microscope (SEM) analysis, and the results are shown in FIGS. 5 to 8.

[0188] FIG. 5 is a SEM image of the positive electrode active material according to Example 1, and FIG. 6 is a SEM image of the positive electrode active material according to Comparative Example 1. Additionally, FIG. 7 is an SEM image of the positive electrode layer according to Example 1, and FIG. 8 is an SEM image of the positive electrode layer according to Comparative Example 1.

[0189] Specifically, the SEM images of FIGS. 5 and 6 are the results obtained by measuring cross-sectional samples of the positive electrode active materials according to Example 1 and Comparative Example 1 in each region of about 12 μm X 12 μm under a condition of 10 kV by using a high-resolution scanning electron microscope (HR-SEM).

[0190] In addition, the SEM images of FIGS. 7 and 8 are the results obtained in the following method. After breaking chips of the all-solid-state battery cells of Example 1 and Comparative Example 1, each cross-sectional sample was obtained by separating a region where at least one positive electrode layer was visible at a place close to an external electrode of a positive electrode in a stack. The obtained cross-sectional sample was measured in a region of about 26 μm X 26 μm under the condition of 10 kV by using the high-resolution scanning electron microscope (HR-SEM).

[0191] Referring to FIGS. 5 and 6, the positive electrode active material of Example 1, unlike that of Comparative Example 1, was confirmed that a surface layer was present in the form of an island on at least a portion of the surface of a core. In addition, referring to FIGS. 7 and 8, the positive electrode active material of Example 1, as the surface layer was present on the surface of the core, was confirmed to have almost no damage on the surface of the positive electrode active material. On the other hand, the positive electrode active material of Comparative Example 1, of which the surface was not coated, exhibited lots of surface damages due to corrosion of the material, wherein crystallinity of a layered structure of the positive electrode active material may easily collapse during charge and discharge, resultantly failing in realizing capacity.

[0192] Evaluation 2: ICP-OES Analysis

[0193] The positive electrode active materials according to Examples 1 to 3 and Comparative Examples 1 to 9 were subjected to Inductively coupled plasma-optical scanning electron microscope (ICP-OES) analysis to check a composition of a surface layer on the surface of a core. The results are shown in Table 1.

[0194] The ICP-OES analysis was performed by dissolving each of the positive electrode active materials in nitric acid and then, diluting the obtained solution to detect components.

[0195] Evaluation 3: Capacity

[0196] The all-solid-state battery cells of Examples 1 to 3 and Comparative Examples 1 to 9 were measured with respect to capacity, and the results are shown in Table 1.

[0197] Specifically, each of the cells was 5 cycles charged and discharged in a CC (constant current) mode at a rate of 4 mA to measure discharge capacity.

[0198] Evaluation 4: Energy Density

[0199] The all-solid-state battery cells of Examples 1 to 3 and Comparative Examples 1 to 9 were measured with respect to energy density, and the results are shown in Table 1.

[0200] The energy density was calculated according to the following equation. Specifically, in the following equation, capacity represents a value obtained in Evaluation 3 and the energy density was measured under a rated voltage condition of 3.78 V, when lithium metal oxide is LiCoO2, 3.75 V, when lithium metal oxide is LiNi0.8Co0.1Mn0.1O2, and 3.20 V, when lithium metal oxide is LiFePO4.

[0201] Energy density (Wh / L) = (capacity x voltage) / volume

[0202] Lithium metal oxideWhether surface layer existsAmorphous glass compositionCapacity (mAh)Energy density(Wh / L)Example 1LiCoO2○Li, Si, B, Al, and O43.6235Example 2LiNi0.8Co0.1Mn0.1O2○Li, Si, B, Al, and O44.6240Example 3LiFePO4○Li, Si, B, Al, and O42.8205Comparative Example 1LiCoO2X-29.1160Comparative Example 2LiCoO2○Li, Si and O26.2144Comparative Example 3LiCoO2○Li, Si, Al and O25.2140Comparative Example 4LiNi0.8Co0.1Mn0.1O2X-30.1165Comparative Example 5LiNi0.8Co0.1Mn0.1O2○Li, Si and O27.0150Comparative Example 6LiNi0.8Co0.1Mn0.1O2○Li, Si, Al and O28.2155Comparative Example 7LiFePO4X-28.0140Comparative Example 8LiFePO4○Li, Si and O26.5130Comparative Example 9LiFePO4○Li, Si, Al and O25.2125

[0203] Referring to Table 1, Examples 1 to 3 were confirmed that a surface layer on the surface of lithium metal oxide was formed of amorphous glass including elements of Li, Si, B, Al, and O. Accordingly, Examples 1 to 3, compared with Comparative Examples 1 to 9, exhibited high capacity and energy density.

[0204] On the contrary, Comparative Examples 1, 4, and 7, in which amorphous glass was not present on the surface of lithium metal oxide, and Comparative Example 2, 3, 5, 6, 8, and 9, in which amorphous glass was present on the surface of lithium metal oxide but did not include some of the elements, were confirmed that both of capacity and energy density were significantly deteriorated.

[0205] It is to be understood that although the preferred embodiment of the present invention has been described above, the present invention is not limited thereto, but can be implemented in various modifications within the scope of the claims, the detailed description of the present invention, and the accompanying drawings, which also fall within the scope of the present invention.

[0206] <Description of Symbols>

[0207] 100: all-solid-state battery

[0208] 110: stack

[0209] 112, 114: external electrode

[0210] 120: positive electrode layer

[0211] 121, 122: positive electrode active material layer

[0212] 123: positive electrode current collector

[0213] 130: solid electrolyte layer

[0214] 140: negative electrode layer

[0215] 141, 142: negative electrode active material layer

[0216] 143: negative current collector

[0217] 150: margin insulating layer

Claims

1.A positive electrode active material for an all-solid-state battery, comprisinga core including lithium metal oxide; anda surface layer disposed on at least a portion of a surface of the core and including an amorphous glass comprising Li, Si, B, Al, and O.2.The positive electrode active material of claim 1, whereinLi is included in an amount of 30 atomic% to 60 atomic% based on a total amount of the amorphous glass.3.The positive electrode active material of claim 1, whereinB is included in an amount of 10 atomic% to 50 atomic% based on a total amount of the amorphous glass.4.The positive electrode active material of claim 1, whereinSi is included in an amount of 10 atomic% to 20 atomic% based on a total amount of the amorphous glass.5.The positive electrode active material of claim 1, whereinAl is included in an amount of 0.1 atomic% to 10 atomic% based on a total amount of the amorphous glass the amorphous glass.6.The positive electrode active material of claim 1, whereinthe amorphous glass further comprises one or more additional elements selected from Ba, Zn, Na, Mg, K, Ca, Ti, Mn, Fe, P, and Cl.7.The positive electrode active material of claim 6, whereinthe one or more additional elements are included in an amount of 0.5 atomic% to 20 atomic% based on a total amount of the amorphous glass.8.The positive electrode active material of claim 1, whereina thickness of the surface layer is 0.5% to 10% of the diameter of the core.9.The positive electrode active material of claim 1, whereinthe surface layer is disposed on a portion of the surface of the core, or on an entirety of the surface of the core.10.The positive electrode active material of claim 1, whereinthe amorphous glass is included in an amount of 2 parts by weight to 10 parts by weight based on 100 parts by weight of the lithium metal oxide.11.A positive electrode layer for an all-solid-state battery comprising the positive electrode active material of any one of claim 1 to claim 10.12.An all-solid-state battery, comprisinga positive electrode layer including a positive electrode active material; a negative electrode layer; anda solid electrolyte layer between the positive electrode layer and the negative electrode layer,wherein the positive electrode active material comprisesa core including lithium metal oxide, anda surface layer disposed on at least a portion of a surface of the core and including an amorphous glass comprising Li, Si, B, Al, and O.13.The all-solid-state battery of claim 12, whereinLi is included in an amount of 30 atomic% to 60 atomic% based on a total amount of the amorphous glass.14.The all-solid-state battery of claim 12, whereinB is included in an amount of 10 atomic% to 50 atomic% based on a total amount of the amorphous glass.15.The all-solid-state battery of claim 12, whereinSi is included in an amount of 10 atomic% to 20 atomic% based on a total amount of the amorphous glass.16.The all-solid-state battery of claim 12, whereinAl is included in an amount of 0.1 atomic% to 10 atomic% based on a total amount of the amorphous glass.17.The all-solid-state battery of claim 12, whereinthe amorphous glass further comprises one or more additional elements selected from Ba, Zn, Na, Mg, K, Ca, Ti, Mn, Fe, P, and Cl.18.The all-solid-state battery of claim 17, whereinthe one or more additional elements are included in an amount of 0.5 atomic% to 20 atomic% based on a total amount of the amorphous glass.19.The all-solid-state battery of claim 12, whereina thickness of the surface layer is 0.5% to 10% of the diameter of the core.20.The all-solid-state battery of claim 12, whereinthe amorphous glass is included in an amount of 2 parts by weight to 10 parts by weight based on 100 parts by weight of the lithium metal oxide.

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