All-solid-state battery

Abstract

Provided is an all-solid-state battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer, wherein at least one of the positive electrode layer and the negative electrode layer includes a current collecting layer and an active material layer, at least one of the current collecting layers and at least one of the active material layers includes a solid electrolyte, the solid electrolyte of the current collecting layer has lower ionic conductivity than the solid electrolyte of the active material layer, the solid electrolyte of the current collecting layer includes at least one selected from a lithium borosilicate-based compound; and at least one oxide selected from B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3, and the solid electrolyte of the active material layer includes at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound.

Description

ALL-SOLID-STATE BATTERY

[0001] The present disclosure relates to an all-solid-state battery.

[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 may 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] 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 an all-solid-state battery having excellent capacity characteristics due to reduced occurrence of micro-shorts.

[0007] An embodiment provides an all-solid-state battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer stacked between the positive electrode layer and the negative electrode layer, wherein at least one of the positive electrode layer and the negative electrode layer includes a current collecting layer and an active material layer disposed on at least one surface of the current collecting layer, at least one of the current collecting layers and at least one of the active material layers includes a solid electrolyte, the solid electrolyte of the current collecting layer has lower ionic conductivity than the solid electrolyte of the active material layer, the solid electrolyte of the current collecting layer includes at least one selected from a lithium borosilicate-based compound; and at least one oxide selected from the group consisting of B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3, and the solid electrolyte of the active material layer includes at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound.

[0008] An embodiment provides an all-solid-state battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer stacked between the positive electrode layer and the negative electrode layer, wherein the positive electrode layer includes a positive electrode current collecting layer including a solid electrolyte, and a positive electrode active material layer disposed on at least one surface of the positive electrode current collecting layer and including a solid electrolyte, the negative electrode layer includes a negative electrode current collecting layer including a solid electrolyte, and a negative electrode active material layer disposed on at least one surface of the negative electrode current collecting layer and including a solid electrolyte, the solid electrolyte of the positive electrode current collecting layer, the solid electrolyte of the positive electrode active material layer, the solid electrolyte of the negative electrode current collecting layer, and the solid electrolyte of the negative electrode active material layer are the same or different from each other, and at least one of the solid electrolyte of the positive electrode current collecting layer and the solid electrolyte of the negative electrode current collecting layer has lower ionic conductivity than at least one of the solid electrolyte of the positive electrode active material layer and the solid electrolyte of the negative electrode active material layer, at least one of the solid electrolyte of the positive electrode current collecting layer and the solid electrolyte of the negative electrode current collecting layer includes a lithium borosilicate-based compound; and at least one selected from at least one oxide selected from the group consisting of B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3, and at least one of the solid electrolyte of the positive electrode active material layer and the solid electrolyte of the negative electrode active material layer includes at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound.

[0009] An embodiment provides an all-solid-state battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer stacked between the positive electrode layer and the negative electrode layer, wherein the positive electrode layer includes a positive electrode current collecting layer including a solid electrolyte, and a positive electrode active material layer disposed on at least one surface of the positive electrode current collecting layer and including a solid electrolyte, the negative electrode layer includes a negative electrode active material layer including a solid electrolyte, the solid electrolyte of the positive electrode current collecting layer, the solid electrolyte of the positive electrode active material layer, and the solid electrolyte of the negative electrode active material layer are the same or different from each other, and the solid electrolyte of the positive electrode current collecting layer has lower ionic conductivity than at least one of the solid electrolyte of the positive electrode active material layer and the solid electrolyte of the negative electrode active material layer, the solid electrolyte of the positive electrode current collecting layer includes at least one selected from a lithium borosilicate-based compound; and at least one oxide selected from the group consisting of B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3, and at least one of the solid electrolyte of the positive electrode active material layer and the solid electrolyte of the negative electrode active material layer includes at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound.

[0010] An embodiment provides an all-solid-state battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer stacked between the positive electrode layer and the negative electrode layer, wherein the positive electrode layer includes a positive electrode active material layer including a solid electrolyte, the negative electrode layer includes a negative electrode current collecting layer including a solid electrolyte, and a negative electrode active material layer disposed on at least one surface of the negative electrode current collecting layer and including a solid electrolyte, the solid electrolyte of the positive electrode active material layer, the solid electrolyte of the negative electrode current collecting layer, and the solid electrolyte of the negative electrode active material layer are the same or different from each other, and the solid electrolyte of the negative electrode current collecting layer has lower ionic conductivity than at least one of the solid electrolyte of the negative electrode active material layer and the solid electrolyte of the positive electrode active material layer, the solid electrolyte of the negative electrode current collecting layer includes lithium borosilicate-based compound; and at least one oxide selected from the group consisting of B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3, and at least one of the solid electrolyte of the negative electrode active material layer and the solid electrolyte of the positive electrode active material layer includes at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound.

[0011] An all-solid-state battery according to an embodiment can reduce the occurrence of micro-shorts by minimizing the occurrence of leakage current, and thus has excellent capacity characteristics and can reduce the self-discharge rate.

[0012] FIG. 1 is a perspective view showing an all-solid-state battery according to an embodiment.

[0013] FIG. 2 is a cross-sectional view of the all-solid-state battery taken along line I-I' of FIG. 1.

[0014] FIG. 3 is an exploded perspective view illustrating the structure of a stack in the all-solid-state battery of FIG. 1.

[0015] FIG. 4 is a cross-sectional view of an all-solid-state battery according to another embodiment.

[0016] FIG. 5 is a cross-sectional view of an all-solid-state battery according to another embodiment.

[0017] FIG. 6 is a scanning electron microscope (SEM) image of a cross-section of an all-solid-state battery according to Example 2.

[0018] Hereinafter, the present disclosure will be described in detail 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 the constituent elements does not reflect the actual size.

[0019] The accompanying drawings are intended only to facilitate an understanding of the e 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] In addition, the phrase "on a plane" means a view from a position above the object 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.

[0024] 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.

[0025] FIG. 1 is a perspective view showing an all-solid-state battery according to an embodiment, FIG. 2 is a cross-sectional view of the all-solid-state battery taken along line I-I' of FIG. 1, and FIG. 3 is an exploded perspective view showing the structure of a stack in the all-solid-state battery of FIG. 1.

[0026] The L-axis, W-axis, and T-axis shown in FIGS. 1 to 3 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).

[0027] Referring to FIGS. 1 to 3, an all-solid-state battery 100 according to an embodiment includes a stack 110 and external electrodes 112 and 114 disposed on the outer surface of the stack 110. The external electrodes 112 and 114 may include a first external electrode 112 and a second external electrode 114 arranged at opposite ends in the length direction (L-axis direction) of the stack 110.

[0028] 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.

[0029] 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.

[0030] The stack 110 of the all-solid-state battery may have, for example, a roughly hexahedral shape.

[0031] 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.

[0032] A stack 110 of an all-solid-state battery 100 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.

[0033] For example, the electrode layer disposed at the uppermost end 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 arranged at the lowermost end of the stack 110 may be a negative electrode layer 140 or a positive electrode layer 120.

[0034] The all-solid-state battery according to an embodiment is not limited to the structures of FIGS. 2 and 3, and may include various structures of FIGS. 4 and 5.

[0035] According to an embodiment, at least one of the positive electrode layer and the negative electrode layer may include a current collecting layer and an active material layer disposed on at least one surface of the current collecting layer in a stacking direction. That is, both the positive electrode layer and the negative electrode layer may include a current collecting layer and an active material layer, or the positive electrode layer may include a current collecting layer and an active material layer, or the negative electrode layer may include a current collecting layer and an active material layer. Specifically, an all-solid-state battery according to an embodiment may have a structure in which the current collecting layer is included in both the positive electrode layer and the negative electrode layer as shown in FIG. 2, a structure in which the current collecting layer is included only in the positive electrode layer as shown in FIG. 4, or a structure in which the current collecting layer is included only in the negative electrode layer as shown in FIG. 5. Here, the current collecting layer and the active material layer included in the positive electrode layer may be referred to as a positive electrode current collecting layer and a positive electrode active material layer, respectively. Likewise, the current collecting layer and the active material layer included in the negative electrode layer may be referred to as a negative electrode current collecting layer and a negative electrode active material layer, respectively.

[0036] In the all-solid-state batteries of various structures described above, at least one of the current collecting layers may include a solid electrolyte, and at least one of the active material layers may include a solid electrolyte.

[0037] At this time, the solid electrolyte included in the current collecting layer may have lower ionic conductivity than the solid electrolyte included in the active material layer.

[0038] Specifically, the solid electrolyte of the current collecting layer may include at least one selected from a lithium borosilicate-based compound; and at least one oxide selected from B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3. Additionally, the solid electrolyte of the active material layer may include at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound.

[0039] The current collecting layer is a layer that secures an electron conducting path between the electrode layers, such as the positive electrode layer and the negative electrode layer, and the external electrode, and includes a current collector with excellent electron conductivity. In addition, the current collecting layer includes a portion of a solid electrolyte to secure simultaneous sintering of the electrode layer and the solid electrolyte layer. However, if the current collecting layer includes a solid electrolyte with excellent ionic conductivity, ions can move through the current collecting layer, and thus the direction of ion movement is not constant, causing leakage current. This can cause problems with current leakage during charging or self-discharge when left unattended. That is, if current leakage occurs during charging, a micro-short phenomenon occurs, and the more severe the current leakage, the lower the charging voltage at which the micro-short phenomenon occurs. If a micro-short occurs, the charging voltage no longer increases, which causes a problem in which the charging capacity decreases. In addition, the faster self-discharge progresses in a charged state, the more difficult it is to store the battery for a long time, and self-discharge is also affected by the degree of current leakage.

[0040] According to an embodiment, the solid electrolyte of the current collecting layer has lower ionic conductivity than the solid electrolyte of the active material layer, and when the compounds which are different materials are used as the solid electrolyte of the current collecting layer and the solid electrolyte of the active material layer, the leakage current generation inside the all-solid-state battery can be minimized by maintaining electron conductivity while suppressing ion movement in the current collecting layer. Accordingly, the all-solid-state battery according to an embodiment can have excellent capacity characteristics by reducing the occurrence of micro-shorts, and can also lower the self-discharge rate.

[0041] Specifically, the structure of an all-solid-state battery according to an embodiment is described in detail with reference to FIGS. 2, 4, and 5.

[0042] Referring to FIG. 2, 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 a stacking direction.

[0043] The positive electrode layer 120 may include a positive electrode current collecting layer 123 and a positive electrode active material layers 121 and 122 disposed on at least one surface of the positive electrode current collecting layer 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 collecting layer 123 and a second positive electrode active material layer 122 disposed on the other surface of the positive electrode current collecting layer 123. For example, when the positive electrode layer 120 is arranged at the uppermost end 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 arranged on one surface of the positive electrode current collecting layer 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 collecting layer 123.

[0044] The positive electrode current collector layer 123 may include a positive electrode current collector and a solid electrolyte. In the present specification, the solid electrolyte included in the positive electrode current collecting layer is referred to as 'solid electrolyte A.'

[0045] The positive electrode current collector and the solid electrolyte A may be included in a weight ratio of 1:10 to 10:1, for example, a weight ratio of 1:5 to 5:1. When the positive electrode current collector and the solid electrolyte A are included in the above ratio, the solid electrolyte A functions as an ion conducting channel within the positive electrode layer, thereby controlling the ionic conductivity of the positive electrode layer to an appropriate level.

[0046] The positive electrode active material layers 121 and 122 may include a positive electrode active material and a solid electrolyte. In the present specification, the solid electrolyte included in the positive electrode active material layer is referred to as 'solid electrolyte B.'

[0047] The positive electrode active material and the solid electrolyte B may be included in a weight ratio of 1:10 to 10:1, for example, a weight ratio of 1:5 to 5:1. When the positive electrode active material and the solid electrolyte B are included in the above ratio, the solid electrolyte B functions as an ion conducting channel within the positive electrode layer, thereby controlling the ionic conductivity of the positive electrode layer to an appropriate level.

[0048] The negative electrode layer 140 may include a negative electrode current collecting layer 143 and negative electrode active material layers 141 and 142 disposed on at least one surface of the negative electrode current collecting layer 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 collecting layer 143 and a second negative electrode active material layer 142 disposed on the other surface of the negative electrode current collecting layer 143. For example, when the negative electrode layer 140 is arranged 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 arranged on one surface of the negative electrode current collecting layer 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 collecting layer 143.

[0049] The negative electrode current collector layer 143 may include a negative electrode current collector and a solid electrolyte. In the present specification, the solid electrolyte included in the negative electrode current collecting layer is referred to as 'solid electrolyte C.'

[0050] The negative electrode current collector and the solid electrolyte C may be included in a weight ratio of 1:10 to 10:1, for example, a weight ratio of 1:5 to 5:1. When the negative electrode current collector and the solid electrolyte C are included in the above ratio, the solid electrolyte C functions as an ion conducting channel within the negative electrode layer, thereby controlling the ionic conductivity of the negative electrode layer to an appropriate level.

[0051] The negative electrode active material layers 141 and 142 may include a negative electrode active material and a solid electrolyte. In this specification, the solid electrolyte included in the negative electrode active material layer is referred to as 'solid electrolyte D.'

[0052] The negative electrode active material and the solid electrolyte D may be included in a weight ratio of 1:10 to 10:1, for example, a weight ratio of 1:5 to 5:1. When the negative electrode active material and the solid electrolyte D are included in the above ratio, the solid electrolyte D functions as an ion conducting channel in the negative electrode layer, thereby controlling the ionic conductivity of the negative electrode layer to an appropriate level.

[0053] The positive electrode current collector, the positive electrode active material, the negative electrode current collector, and the negative electrode active material will be described later.

[0054] The solid electrolyte of the positive electrode current collecting layer 123, the solid electrolyte of the positive electrode active material layers 121 and 122, the solid electrolyte of the negative electrode current collecting layer 143, and the solid electrolytes of the negative electrode active material layers 141 and 142, i.e., the solid electrolytes A, B, C and D, may be the same as or different from each other, for example, the solid electrolyte included in the solid electrolyte layer 130 described below may be used. Here, according to an embodiment, at least one of the solid electrolyte of the positive electrode current collecting layer 123 and the solid electrolyte of the negative electrode current collecting layer 143 may use a material having lower ionic conductivity than at least one of the solid electrolytes of the positive electrode active material layers 121 and 122 and the solid electrolytes of the negative electrode active material layers 141 and 142. That is, at least one of the solid electrolytes A and C may have lower ionic conductivity than at least one of the solid electrolytes B and D.

[0055] Specifically, at least one of the solid electrolyte of the positive electrode current collecting layer 123 and the solid electrolyte of the negative electrode current collecting layer 143, that is, at least one of the solid electrolytes A and C, may include at least one selected from a lithium borosilicate-based compound; and at least one oxide selected from the group consisting of B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3. In addition, at least one of the solid electrolyte of the positive electrode active material layers 121 and 122 and the solid electrolyte of the negative electrode active material layers 141 and 142, and at least one of the solid electrolytes B and D may include at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound.

[0056] In this way, when the solid electrolyte of the current collecting layer, that is, at least one of the solid electrolytes A and C, has lower ionic conductivity than the solid electrolyte of the active material layer, that is, at least one of the solid electrolytes B and D, and different compounds are used as the solid electrolyte of the current collecting layer and the solid electrolyte of the active material layer, the occurrence of micro-shorts can be reduced by minimizing the occurrence of leakage current inside the all-solid-state battery, and thus, excellent capacity characteristics can be achieved as well as a low self-discharge rate.

[0057] For example, the solid electrolyte A may have lower ionic conductivity than at least one of the solid electrolytes B and D, and for example, the solid electrolyte A may have lower ionic conductivity than the solid electrolyte B. Additionally, the solid electrolyte C may have lower ionic conductivity than at least one of the solid electrolytes B and D, and for example, the solid electrolyte C may have lower ionic conductivity than the solid electrolyte D.

[0058] As another example, the solid electrolyte A may be at least one selected from a lithium borosilicate-based compound; and at least one oxide selected from the group consisting of B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3, and the solid electrolytes B, C, and D may be at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound. For example, the solid electrolyte A may be a lithium borosilicate-based compound, and the solid electrolytes B, C, and D may be lithium borosilicate-based compounds.

[0059] As another example, the solid electrolyte A may be at least one selected from a lithium borosilicate-based compound; and at least one oxide selected from the group consisting of B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O, for example, the solid electrolyte A may be a lithium borosilicate-based compound, and the solid electrolytes B and D may be at least one selected from a lithium chloroboracite-based compound, a garnet-type compound and a LISICON-type compound, for example, the solid electrolytes B and D may be lithium chloroboracite-based compounds, and the solid electrolyte C may be another general solid electrolyte, for example, a glass not including lithium, or a garnet-type compound.

[0060] As another example, the solid electrolytes A and C may be at least one selected from a lithium borosilicate-based compound; and at least one oxide selected from the group consisting of B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3, and the solid electrolytes B and D may be at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound. For example, the solid electrolytes A and C may be lithium borosilicate-based compounds, and the solid electrolytes B and D may be lithium chloroboracite-based compounds.

[0061] FIG. 4 is a cross-sectional view of an all-solid-state battery according to another embodiment.

[0062] Referring to FIG. 4, an all-solid-state battery 200 according to an embodiment includes a positive electrode layer 220, a negative electrode layer 240, and a solid electrolyte layer 230 disposed between the positive electrode layer 220 and the negative electrode layer 240 in a stacking direction.

[0063] The positive electrode layer 220 may include a positive electrode current collecting layer 223 including a solid electrolyte, and positive electrode active material layers 221 and 222 disposed on at least one surface of the positive electrode current collecting layer 223 and including a positive electrode active material and a solid electrolyte.

[0064] The negative electrode layer 240 may include a negative electrode active material layer (not shown) including a negative electrode active material and a solid electrolyte. That is, in the all-solid-state battery according to FIG. 4, the negative electrode layer 240 may be composed only of a negative electrode active material layer without including a negative electrode current collecting layer.

[0065] The solid electrolyte of the positive electrode current collecting layer 223, the solid electrolyte of the positive electrode active material layers 221 and 222, and the solid electrolyte of the negative electrode active material layer, i.e., the solid electrolytes A, B, and D, may be the same as or different from each other, for example, the solid electrolyte included in the solid electrolyte layer 230 described below may be used. Here, according to an embodiment, the solid electrolyte of the positive electrode current collecting layer 223 may use a material having lower ionic conductivity than at least one of the solid electrolyte of the positive electrode active material layers 221 and 222 and the solid electrolyte of the negative electrode active material layer (not shown). That is, solid electrolyte A may have lower ionic conductivity than at least one of solid electrolytes B and D. For example, the solid electrolyte A may have lower ionic conductivity than the solid electrolyte B.

[0066] Specifically, the solid electrolyte of the positive electrode current collecting layer 223, i.e., the solid electrolyte A, may include at least one selected from a lithium borosilicate-based compound; and at least one oxide selected from the group consisting of B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3. In addition, at least one of the solid electrolyte of the positive electrode active material layers 221 and 222 and the solid electrolyte of the negative electrode active material layer (not shown), that is, at least one of the solid electrolytes B and D, may include at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound.

[0067] In this way, when the solid electrolyte of the current collecting layer has lower ionic conductivity than the solid electrolyte of the active material layer, and different compounds are used in the solid electrolyte of the current collecting layer and the solid electrolyte of the active material layer, the occurrence of micro-shorts may be reduced by minimizing the occurrence of leakage current inside the all-solid-state battery, and thus excellent capacity characteristics can be achieved as well as a low self-discharge rate.

[0068] For example, the solid electrolyte A may be at least one selected from a lithium borosilicate-based compound; and at least one oxide selected from the group consisting of B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3, and the solid electrolytes B and D may be at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound. For example, the solid electrolyte A may be a lithium borosilicate-based compound, and the solid electrolytes B and D may be lithium chloroboracite-based compounds.

[0069] As another example, the solid electrolyte A may be at least one selected from a lithium borosilicate-based compound; and at least one oxide selected from the group consisting of B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3, for example, the solid electrolyte A may be a lithium borosilicate-based compound, and the solid electrolyte B may be at least one selected from a lithium chloroboracite-based compound, a garnet-type compound and a LISICON-type compound, for example, the solid electrolyte B may be a lithium chloroboracite-based compound, and the solid electrolyte D may be another general solid electrolyte, for example, a glass not including lithium, or a garnet-type compound.

[0070] FIG. 5 is a cross-sectional view of an all-solid-state battery according to another embodiment.

[0071] Referring to FIG. 5, an all-solid-state battery 300 according to one embodiment includes a positive electrode layer 320, a negative electrode layer 340, and a solid electrolyte layer 330 disposed between the positive electrode layer 320 and the negative electrode layer 340 in a stacking direction.

[0072] The positive electrode layer 320 may include a positive electrode active material layer (not shown) including a positive electrode active material and a solid electrolyte. That is, in the all-solid-state battery according to FIG. 5, the positive electrode layer 320 may be composed only of a positive electrode active material layer without including a positive electrode current collecting layer.

[0073] The negative electrode layer 340 may include a negative electrode current collecting layer 343 including a solid electrolyte, and negative electrode active material layers 341 and 342 disposed on at least one surface of the negative electrode current collecting layer 343 and including a negative electrode active material and a solid electrolyte.

[0074] The solid electrolyte of the positive electrode active material layer, the solid electrolyte of the negative electrode current collecting layer 343, and the solid electrolyte of the negative electrode active material layers 341 and 342, i.e., the solid electrolytes B, C, and D, may be the same as or different from each other, and the solid electrolyte included in the solid electrolyte layer 330 described later may be used. According to an embodiment, the solid electrolyte of the negative electrode current collecting layer 343 may use a material having lower ionic conductivity than at least one of the solid electrolyte of the negative electrode active material layers 341 and 342 and the solid electrolyte of the positive electrode active material layer (not shown). That is, the solid electrolyte C may have lower ionic conductivity than at least one of the solid electrolytes B and D. For example, the solid electrolyte of the negative electrode current collecting layer 343, i.e., the solid electrolyte C, may have lower ionic conductivity than the solid electrolyte of the negative electrode active material layers 341 and 342, i.e., the solid electrolyte D.

[0075] Specifically, the solid electrolyte of the negative electrode current collecting layer 343 may include at least one selected from a lithium borosilicate-based compound; and at least one oxide selected from the group consisting of B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3. In addition, at least one of the solid electrolyte of the negative electrode active material layers 341 and 342 and the solid electrolyte of the positive electrode active material layer (not shown) may include at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound.

[0076] In this way, when the solid electrolyte of the current collecting layer has lower ionic conductivity than the solid electrolyte of the active material layer, and different compounds are used in the solid electrolyte of the current collecting layer and the solid electrolyte of the active material layer, the occurrence of micro-shorts may be reduced by minimizing the occurrence of leakage current inside the all-solid-state battery, and thus excellent capacity characteristics can be achieved as well as a low self-discharge rate.

[0077] For example, the solid electrolyte C may be at least one selected from a lithium borosilicate-based compound; and at least one oxide selected from the group consisting of B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3, and the solid electrolytes B and D may be at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound. For example, the solid electrolyte C may be a lithium borosilicate-based compound and the solid electrolytes B and D may be lithium chloroboracite-based compounds.

[0078] As another example, the solid electrolyte C may be at least one selected from a lithium borosilicate-based compound; and at least one oxide selected from the group consisting of B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3, for example, the solid electrolyte C may be a lithium borosilicate-based compound and the solid electrolyte D may be at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound, for example, the solid electrolyte D may be a lithium chloroboracite-based compound, and the solid electrolyte B may be another general solid electrolyte, for example, a glass not including lithium, or a garnet-type compound.

[0079] Specifically, the ionic conductivity of the solid electrolyte of the current collecting layer may be greater than or equal to 1.0E-12 S / cm and less than or equal to 1.0E-06 S / cm, for example greater than or equal to 1.0E-11 S / cm and less than or equal to 1.0E-07 S / cm. Additionally, the ionic conductivity of the solid electrolyte of the active material layer may be greater than 1.0E-06 S / cm and less than or equal to 1.0E-02 S / cm, for example greater than 1.0E-05 S / cm and less than or equal to 1.0E-03 S / cm. When the ionic conductivity of the solid electrolyte of the current collecting layer and the solid electrolyte of the active material layer are within the above ranges, the occurrence of micro-shorts may be reduced by minimizing the occurrence of leakage current within the all-solid-state battery.

[0080] Herein, the solid electrolyte of the current collecting layer, in the structure shown in FIG. 2, may be at least one of the solid electrolyte of the positive electrode current collecting layer 123 and the solid electrolyte of the negative electrode current collecting layer 143, that is, at least one of the solid electrolytes A and C, in the structure of FIG. 4, may be the solid electrolyte of the positive electrode current collecting layer 223, that is, the solid electrolyte A, and in the structure of FIG. 5, the solid electrolyte of the negative electrode current collecting layer 343, that is, the solid electrolyte C. In addition, the solid electrolyte of the active material layer, in the structure of FIG. 2, may be at least one of the solid electrolyte of the positive electrode active material layers 121 and 122 and the solid electrolyte of the negative electrode active material layers 141 and 142, that is, at least one of the solid electrolytes B and D, in the structure of FIG. 4, at least one of the solid electrolyte of the positive electrode active material layers 221 and 222 and the solid electrolyte of the negative electrode active material layer (not shown), that is, at least one of the solid electrolytes B and D, and in the structure of FIG. 5, may be at least one of the solid electrolyte of the negative electrode active material layers 341 and 342 and the solid electrolyte of the positive electrode active material layer (not shown), that is, at least one of the solid electrolytes B and D. This is equally applied to the solid electrolyte of the current collecting layer and the solid electrolyte of the active material layer, which are mentioned below.

[0081] The ionic conductivity of the solid electrolyte is measured in the following method. A chip of an all-solid-state battery is polished and ion-milled to expose an active material layer. A portion of the exposed active material layer is sampled as a rectangular hexahedral piece. For example, the rectangular hexahedral piece sample may have a shortest thickness (T) and a longer length (L) and width (W) than the thickness (T). In the obtained sample, an electrode made of gold (Au) or platinum (Pt) is formed on the TW surface and then, connected to an impedance measuring apparatus. The impedance measuring apparatus is used to measure AC impedance under conditions of a frequency of 106Hz to 10-1Hz and a voltage of 50 mV to 500 mV at room temperature of 25 °C. The impedance measurement result may be used with a size of the sample to calculate the ionic conductivity of the active material layer. Similarly, ionic conductivity the current collecting layer may also be measured in the same manner as above. When ionic conductivity of the active material layer and the current collecting layer are measured, if an active material or a current collecting material is mingled in the rectangular hexahedral sample, because the ionic conductivity is difficult to precisely measure, it is measured where the active material and the current collecting material are not mixed in the sample during the sampling process.

[0082] The lithium borosilicate-based compound used as the solid electrolyte of the current collecting layer is a glass-state electrolyte. The glass means that it is crystallographically amorphous, as evidenced by the observation of a halo in X-ray diffraction or electron diffraction. For example, the lithium borosilicate-based compound may include at least one of lithium (Li), boron (B), silicon (Si), aluminum (Al), phosphorus (P), germanium (Ge), and sulfur (S). For example, the lithium borosilicate-based compound includes lithium (Li), boron (B), and silicon (Si), for example, Li2O―0.5B2O3―0.5SiO2(LBSO). If the lithium borosilicate-based compound is used as the solid electrolyte of the current collecting layer, because the firing may not only be performed at a lower temperature, but also its amorphous state may be maintained during the firing, the ionic conductivity may be realized at an appropriate level.

[0083] The lithium chloroboracite-based compound used as the solid electrolyte of the active material layer may be a glass-ceramic-based electrolyte. Glass-ceramics exhibit peaks and halos in the X-ray diffraction, electron beam diffraction, or the like, which means that crystallographically amorphous and crystalline materials coexist. For example, the lithium chloroboracite-based compound may be Li4B4Al3O12Cl (LCBA). If the lithium chloroboracite-based compound is used as the solid electrolyte of the active material layer, high ionic conductivity may be achieved due to sufficient densification after the firing.

[0084] In addition, the garnet-type compound may include lithium-lanthanum-zirconium-oxide (LLZO) such as Li7La3Zr2O12and the like.

[0085] The LISICON-type compound may be represented by xLi3AO4―(1-x)Li4BO4(A is P, As, or V and B is Si, Ge, or Ti), and may be a solid solution oxide including Li4Zn(GeO4)4, Li10GeP2O12(LGPO), Li3.5Si0.5P0.5O4, Li10.42Si(Ge)1.5P1.5Cl0.08O11.92, or a solid solution sulfide including Li2S-P2S5, Li2S-SiS2, Li2S-SiS2-P2S5, or Li2S-GeS2represented by Li4-xM1-yM'yS4(M is Si, or Ge and M' is P, Al, Zn, or Ga).

[0086] The solid electrolyte of the current collecting layer and the solid electrolyte of the active material layer are subjected to SEM-EDS (scanning electron microscope-energy dispersive spectroscopy) analysis to check components of corresponding material.

[0087] The SEM-EDS analysis is conducted in the following method. After obtaining a cross-sectional sample in which an active material layer and a current collecting layer are exposed by polishing or ion-milling a chip of an all-solid-state battery, the cross-sectional sample is measured with respect to SEM at an accelerating voltage of 10 kV and a magnification of 5000 times. Subsequently, the EDS analysis is performed by designating any point in the current collecting layer and any point in the active material layer are designated in the obtained SEM image to analyze material components of the solid electrolytes at the points. Herein, the EDS measurement is performed for the solid electrolyte rather than the active material or the current collecting material.

[0088] The positive electrode current collector included in the positive electrode current collecting layers 123 and 223 may be formed of, for example, a plate-shaped member or a thin member. As another example, the positive electrode current collector may be a porous structure having a reticulate or mesh shape.

[0089] The positive electrode current collector 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 may be coated with an oxidation-resistant metal or alloy film to prevent oxidation.

[0090] The positive electrode current collector may be made of a carbon-based plate-shaped, thin-walled, or linear member. Specifically, the positive electrode current collector 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.

[0091] The positive electrode active material in the positive electrode active material layers 121, 122, 221, and 222 may be a material including lithium ions and may reversibly intercalate and deintercalate lithium ions. That is, the positive electrode active material includes lithium ions and may play a role in providing lithium ions to the negative electrode when charging the all-solid-state battery. The positive electrode active material may affect the capacity and output of all-solid-state batteries.

[0092] The positive electrode active material may be, for example, compounds represented by the following chemical formulas:

[0093] 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)J2(PO4)3(0≤f≤2); Li(3-f)Fe2(PO4)3(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.

[0094] The positive electrode active material may also be LiCoO2, LiMnxO2x(wherein x is 1 or 2), LiNi1-xMnxO2x(wherein 0<x<1), LiNi1-x-yCoxMnyO2(wherein 0≤x≤0.5, 0≤y≤0.5), LiFePO4, TiS2, FeS2, TiS3, or FeS3.

[0095] For example, the positive electrode active material may be a lithium metal compound including lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium manganese oxide, or a combination thereof.

[0096] The positive electrode active material layers 121, 122, 221, and 222 may further include at least one of a conductive material and a binder.

[0097] 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. 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.

[0098] 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.

[0099] The binder may be used to improve the binding strength between positive electrode 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.

[0100] 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 may have high binding strength.

[0101] The negative electrode current collector included in the negative electrode current collecting layers 143 and 343 may be formed of, for example, a plate-shaped member or a thin member. As another example, the negative electrode current collecting layer 143 may be a porous structure having a reticulate or mesh shape.

[0102] The negative electrode current collector 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 may be coated with an oxidation-resistant metal or alloy film to prevent oxidation.

[0103] The negative electrode current collector may be made of a conductive carbon-based material, similar to the positive electrode current collector.

[0104] The negative electrode active material included in the negative electrode active material layers 141, 142, 341, and 342 can store lithium ions moved from the positive electrode layer and release them when the all-solid-state battery is discharged to generate electrical energy.

[0105] The negative electrode active material may be a carbon-based material, silicon, a silicon oxide, a silicon-based alloy, a silicon-carbon-based material composite, tin, a tin-based alloy, a tin-carbon composite, a metal oxide, or a combination thereof, and may include a lithium metal and / or a lithium metal alloy.

[0106] The lithium metal alloy may include lithium and metal / semi-metal capable of alloying with lithium. For example, the metal / semi-metal that may be alloyed with lithium may be Si, Sn, Al, Ge, Pb, Bi, Sb, a Si-M1 alloy (wherein M1 is an alkali metal, an alkaline earth metal, Group 13 to 16 elements, a transition metal, a rare earth element, or a combination thereof, and does not include Si), a Sn-M2 alloy (wherein M2 is an alkali metal, an alkaline earth metal, Group 13 to 16 elements, a transition metal, a transition metal oxide such as lithium titanium oxide (Li4Ti5O12), a rare earth element, or a combination thereof, and does not include Sn), MnOx(0<x≤2), and the like. Here, 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.

[0107] Additionally, the oxide of a metal / semi-metal that can be alloyed with lithium may be lithium titanium oxide, vanadium oxide, lithium vanadium oxide, SnO2, SiOx(0<x<2), and 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.

[0108] 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.

[0109] The silicon may be Si, SiOx(0<x<2, for example 0.5 to 1.5), Sn, SnO2, or a silicon-containing metal alloy, and 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.

[0110] The negative electrode active material layers 141, 142, 341, and 342 may further include one or more selected from a conductive material and a binder.

[0111] The conductive material is not particularly limited as long as it has conductivity and does not induce chemical changes in the all-solid-state battery. For example, graphite such as natural graphite, artificial graphite, etc.; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, summer black, etc.; a conductive fiber such as a carbon fiber, a metal fiber, etc.; fluorinated carbon; a metal powder such as an aluminum and nickel powder; a conductive oxide such as zinc oxide and potassium titanate; a conductive metal oxide such as titanium oxide; a conductive material such as polyphenylene derivatives, etc. may be used.

[0112] The conductive material may be included in an amount of 0 parts by weight to 5 parts by weight, for example, 0.01 parts by weight to 1 part by weight, or 0.1 parts by weight to 0.5 parts by weight, based on 100 parts by weight of the negative electrode active material. When the content of the conductive material is within the above range, a negative electrode layer having excellent conductivity characteristics may be obtained.

[0113] The binder may be used to improve the binding strength between negative electrode 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.

[0114] 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 electrode active material. When the binder content is within the above range, the negative electrode active material layer may have high binding strength.

[0115] The solid electrolyte layers 130, 230, and 330 includes a solid electrolyte. In the present specification, the solid electrolyte included in the solid electrolyte layers 130, 230, and 330 is referred to as 'solid electrolyte E'.

[0116] The solid electrolyte included in the solid electrolyte layers 130, 230, and 330 may include a glass-ceramic compound or a lithium borosilicate-based compound.

[0117] The glass-ceramic compound may include lithium halide (a halogen element 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 compound is an electrolyte in a mixed state of amorphous and crystalline phases, with some crystallization occurring through sintering.

[0118] The glass-ceramic compound may include amorphous and two or more crystalline phases. Additionally, the crystalline phases included in the glass-ceramic compound may include a lithium compound crystal phase including lithium.

[0119] The glass-ceramic compound 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 compound may include Li2O, B2O3, SiO2, P2O5, GeO2, and LiCl. For example, the glass-ceramic compound may be a lithium chloroboracite-based compound such as Li4B4Al3O12Cl (LCBA).

[0120] The lithium borosilicate-based compound are glass-like electrolytes, and glass means that they are crystallographically amorphous, as evidenced by the observation of a halo in X-ray diffraction or electron diffraction.

[0121] For example, the lithium borosilicate-based compound may include lithium (Li), boron (B), silicon (Si), aluminum (Al), phosphorus (P), germanium (Ge), and sulfur (S).

[0122] Additionally, the solid electrolyte included in the solid electrolyte layers 130, 230, and 330 may include an oxide-based compound, a sulfide-based compound, or a combination thereof.

[0123] The oxide-based compound may be at least one selected from garnet-type, nasicon-type, LISICON-type, perovskite-type, LiPON-type, and amorphous (glass) compounds.

[0124] The garnet-type compound may refer to lithium-lanthanum-zirconium oxide (LLZO) represented by Li7La3Zr2O12, the nasicon-type compound may refer to lithium-aluminum-titanium-phosphate (LATP) of Li1+xAlxTi2-x(PO4)3(0<x<1) where Ti is introduced into Li1+xAlxM2-x(PO4)3(LAMP)-type compound (wherein 0<x<2 and M is Zr, Ti, or Ge), a lithium-aluminum-germanium-phosphate salt (LAGP) represented by Li1+xAlxGe2-x(PO4)3(0<x<1) such as Li1.3Al0.3Ti1.7(PO4)3in which excess lithium is introduced, and / or a lithium-zirconium-phosphate salt (LZP) of LiZr2(PO4)3.

[0125] In addition, the LISICON-type compound may be represented by xLi3AO4-(1-x)Li4BO4(A is P, As, V, etc. and B is Si, Ge, Ti, etc.) and may be a solid solution oxide including Li4Zn(GeO4)4, Li10GeP2O12(LGPO), Li3.5Si0.5P0.5O4, Li10.42Si(Ge)1.5P1.5Cl0.08O11.92, etc., and a solid solution sulfide represented by Li4-xM1-yM'yS4(M is Si, or Ge, and M' is P, Al, Zn, or Ga) including Li2S-P2S5, Li2S-SiS2, Li2S-SiS2-P2S5, or Li2S-GeS2,etc.

[0126] The perovskite-type compound may indicate lithium lanthanum titanate (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.

[0127] The amorphous compound may be Li2O-B2O3-SiO2, Li2O-B2O3-P2O5, Li3BO3-Li2SO4, or Li3BO3-Li2CO3.

[0128] The sulfide-based compound includes sulfur atoms among the electrolyte components and is not particularly limited to specific components, and may include one or more of a crystalline compound, an amorphous compound (glassy compound), and a glass ceramic compound.

[0129] For example, the sulfide-based compound 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.

[0130] For example, the solid electrolyte E may use a material having a higher ionic conductivity than at least one of the solid electrolytes A and C of the current collecting layer. When the solid electrolyte of the current collecting layer has lower ionic conductivity than the solid electrolyte of the solid electrolyte layer, the occurrence of leakage current can be minimized, thereby reducing the occurrence of micro-shorts.

[0131] The solid electrolyte E may include, for example, a lithium chloroboracite-based compound. Additionally, the solid electrolyte E may further include at least one selected from a garnet-type compound and a LISICON-type compound.

[0132] The all-solid-state batteries 100, 200, and 300 according to embodiments may further include margin insulating layers 150, 250, and 350.

[0133] The margin insulating layers 150, 250, and 350 fill regions, on the solid electrolyte layers 130, 230, and 330, excluding the regions where the positive electrode layers 120, 220, and 320 or negative electrode layer 140, 240, and 340 are disposed. When the positive electrode layers 120, 220, and 320 are disposed on a solid electrolyte layers 130, 230, and 330, margin insulating layers 150, 250, and 350 may be disposed in regions excluding the regions where the positive electrode layers 120, 220, and 320 are disposed. Similarly, when a negative electrode layer 140, 240, and 340 are disposed on solid electrolyte layers 130, 230, and 330, margin insulating layers 150, 250, and 350 may be disposed in regions excluding the regions where the negative electrode layer 140, 240, and 340 are disposed. The margin insulating layers 150, 250, and 350 may be disposed in the same layer in the positive electrode layers 120, 220, and 320 and the negative electrode layer 140, 240, and 340, respectively.

[0134] The margin insulating layers 150, 250, and 350 may eliminate the steps between the solid electrolyte layers 130, 230, and 330 and the positive electrode layers 120, 220, and 320 or the steps between the solid electrolyte layers 130, 230, and 330 and the negative electrode layer 140, 240, and 340. Accordingly, the density between the solid electrolyte layer and the electrode layer is increased, so that delamination or warping due to sintering may be prevented during the manufacturing process of the all-solid-state battery.

[0135] The margin insulating layers 150, 250, and 350 may include an insulating material. The insulating material may be for example polyolefin such as polyethylene or polypropylene; polyester such as polyethylene terephthalate (PET); polyurethane; or polyimide.

[0136] Additionally, the margin insulating layers 150, 250, and 350 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, but are not limited thereto.

[0137] Additionally, the margin insulating layers 150, 250, and 350 may include a solid electrolyte. In the present specification, the solid electrolyte included in the margin insulating layers 150, 250, and 350 is referred to as 'solid electrolyte F.'

[0138] The insulating material and the solid electrolyte F may be included in a weight ratio of 1:10 to 10:1.

[0139] The solid electrolyte F can be used among the types of solid electrolytes included in the solid electrolyte layers 130, 230, and 330, i.e., the solid electrolyte E.

[0140] For example, the solid electrolyte F may use a material having a higher ionic conductivity than at least one of the solid electrolytes A and C of the current collecting layer. When the solid electrolyte of the current collecting layer has lower ionic conductivity than the solid electrolyte of the margin insulating layer, the occurrence of leakage current can be minimized, thereby reducing the occurrence of micro-shorts.

[0141] The solid electrolyte F may include, for example, a lithium chloroboracite-based compound. Additionally, the solid electrolyte F may further include at least one selected from a garnet-type compound and a LISICON-type compound.

[0142] In an embodiment, a sintering agent may be included together with the solid electrolyte for simultaneous sintering of heterogeneous solid electrolytes.

[0143] Additionally, the stack 110 according to an embodiment may further include a protective layer disposed as an outermost layer on the upper and lower ends of the stack.

[0144] The protective layer may improve moisture resistance reliability by preventing moisture penetration and prevent damage caused by physical impacts and / or chemical exposure.

[0145] 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.

[0146] Additionally, the protective layer may include the same solid electrolyte as the solid electrolyte included in the aforementioned solid electrolyte layers 130, 230, and 330, but is not limited thereto.

[0147] The all-solid-state batteries 100, 200, and 300 may be manufactured by alternately stacking a plurality of positive electrode layers 120, 220, and 320 and negative electrode layers 140, 240, and 340, interposing a plurality of solid electrolyte layers 130, 230, and 330 therebetween to manufacture a stack 110, and then calcining and then pressurizing / firing the stack 110.

[0148] The calcining may be performed at a temperature of 350 °C to 400 °C and in an air or nitrogen atmosphere. The firing may be performed at a temperature of 400 °C to 600 °C and in an air or nitrogen atmosphere.

[0149] The external electrodes 112 and 114 are disposed on the outer surface of the stack 110.

[0150] On both sides of the stack 110 of the all-solid-state batteries 100, 200, and 300, terminals of the positive electrode current collecting layers 123 and 223 and terminals of the negative electrode current collecting layers 143 and 343 are exposed, and external electrodes 112 and 114 may be connected and coupled to the exposed terminals.

[0151] The external electrodes 112 and 114 may be configured to be connected to the terminal of the positive electrode current collecting layers 123 and 223 to have a positive electrode, and to be connected to the terminal of the negative electrode current collecting layers 143 and 343 to have a negative electrode. If the terminals of the positive electrode current collecting layers 123 and 223 and the terminals of the negative electrode current collecting layers 143 and 343 are configured to face in opposite directions, the external electrodes 112 and 114 can also be disposed on each side.

[0152] The external electrodes 112 and 114 may include conductive metal and glass.

[0153] 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 an alloy thereof.

[0154] 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).

[0155] 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 may 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.

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

[0157]

[0158] (Manufacturing of All-solid-state Battery)

[0159] Example 1

[0160] A positive electrode current collecting layer was formed by mixing graphite and Li2O―0.5B2O3―0.5SiO2(LBSO) (solid electrolyte A) in a weight ratio of 1:1. In addition, a positive electrode layer paste was prepared by mixing LiCoO2, Li4B4Al3O12Cl (LCBA) (solid electrolyte B), carbon black (Li100), and an acryl binder. Herein, LiCoO2and LCBA were mixed in a weight ratio of 3:1, and the carbon black and the acryl binder were mixed in amount of 1 part by weight and 10 parts by weight based on 100 parts by weight of a total amount of LiCoO2and LCBA. Subsequently, the positive electrode layer paste was printed on both surfaces of the positive electrode current collecting layer to form a positive electrode layer green sheet.

[0161] A negative electrode current collecting layer was formed by mixing graphite and Li2O―0.5B2O3―0.5SiO2(LBSO) (solid electrolyte C) in a weight ratio of 1:1. In addition, a negative electrode layer paste was prepared by mixing artificial graphite, Li4B4Al3O12Cl (LCBA) (solid electrolyte D), 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. Subsequently, the negative electrode layer paste was printed on both sides of the negative electrode current collecting layer to form a negative electrode layer green sheet.

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

[0163] Furthermore, a margin insulating layer was formed by mixing Al2O3and Li4B4Al3O12Cl (LCBA) (solid electrolyte F) in a weight ratio of 1:9.

[0164] The formed positive electrode layer green sheet, solid electrolyte layer green sheet, and negative electrode layer green sheet were stacked, and then, the margin insulating layer was disposed in an empty space on the same layer as each of the positive electrode layer green sheet and the negative electrode layer green sheet to form a stack, which was calcinated at 400 °C under an air or nitrogen atmosphere and then, pressurized / fired at 500 °C under the air or nitrogen atmosphere to manufacture an all-solid-state battery cell. The all-solid-state battery cell was manufactured to have a structure shown in FIG. 2.

[0165] Example 2

[0166] A negative electrode layer green sheet was formed by mixing artificial graphite, Li4B4Al3O12Cl (LCBA) (solid electrolyte D), 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.

[0167] An all-solid-state battery cell was manufactured in the same manner as in Example 1 except that the negative electrode layer green sheet formed without the negative electrode current collecting layer was used instead of the negative electrode layer green sheet of Example 1. The all-solid-state battery cell was manufactured to have a structure shown in FIG. 4.

[0168] Example 3

[0169] A positive electrode layer green sheet was formed by mixing LiCoO2, Li4B4Al3O12Cl (LCBA) (solid electrolyte B), carbon black (Li100), and an acryl binder. Herein, LiCoO2and LCBA were mixed in a weight ratio of 3:1, and the carbon black and the acryl binder were mixed in amount of 1 part by weight and 10 parts by weight based on 100 parts by weight of a total amount of LiCoO2and LCBA.

[0170] An all-solid-state battery cell was manufactured in the same manner as in Example 1 except that the positive electrode layer green sheet formed without positive electrode current collecting layer was used instead of the positive electrode layer green sheet of Example 1. The all-solid-state battery cell was manufactured to have a structure shown in FIG. 5.

[0171] Comparative Example 1

[0172] A positive electrode current collecting layer was formed by mixing graphite and Li4B4Al3O12Cl (LCBA) (solid electrolyte A) in a weight ratio of 1:1. In addition, a positive electrode layer paste was prepared by mixing LiCoO2, Li4B4Al3O12Cl (LCBA) (solid electrolyte B), carbon black (Li100), and an acryl binder. Herein, LiCoO2and LCBA were mixed in a weight ratio of 3:1, and the carbon black and the acryl binder were mixed in amount of 1 part by weight and 10 parts by weight based on 100 parts by weight of a total amount of LiCoO2and LCBA. Subsequently, the positive electrode layer paste was printed on both sides of the positive electrode current collecting layer to form a positive electrode layer green sheet.

[0173] A negative electrode current collecting layer was formed by mixing graphite and Li4B4Al3O12Cl (LCBA) (solid electrolyte C) in a weight ratio of 1:1. In addition, a negative electrode layer paste was prepared by mixing artificial graphite, Li4B4Al3O12Cl (LCBA) (solid electrolyte D), 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. Subsequently, the negative electrode layer paste was printed on both sides of the negative electrode current collecting layer to form a negative electrode layer green sheet.

[0174] In addition, a solid electrolyte layer green sheet was formed by using Li4B4Al3O12Cl (LCBA) (solid electrolyte E).

[0175] In addition, a margin insulating layer was formed by mixing Al2O3and Li4B4Al3O12Cl (LCBA) (solid electrolyte F) in a weight ratio of 1:9.

[0176] The formed positive electrode layer green sheet, solid electrolyte layer green sheet, and negative electrode layer green sheet were stacked, and the margin insulating layer was disposed in an empty space on the same layer as the positive electrode layer green sheet and the negative electrode layer green sheet to form a stack, which was calcinated at 400 °C under an air or nitrogen atmosphere and then, pressurized / fired at 500 °C under the air or nitrogen atmosphere to manufacture an all-solid-state battery cell. The all-solid-state battery cell was manufactured to have a structure shown in FIG. 2.

[0177] Comparative Example 2

[0178] A negative electrode layer green sheet was formed by mixing artificial graphite, Li4B4Al3O12Cl (LCBA) (solid electrolyte D), 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.

[0179] An all-solid-state battery cell was manufactured in the same manner as in Comparative Example 1 except that the negative electrode layer green sheet formed without the negative electrode current collecting layer was used instead of the negative electrode layer green sheet of Comparative Example 1. The all-solid-state battery cell was manufactured to have a structure shown in FIG. 4.

[0180] Comparative Example 3

[0181] A positive electrode layer green sheet was formed by mixing LiCoO2, Li4B4Al3O12Cl (LCBA) (solid electrolyte B), carbon black (Li100), and an acryl binder. Herein, LiCoO2and LCBA were mixed in a weight ratio of 3:1, and the carbon black and the acryl binder were mixed in amount of 1 part by weight and 10 parts by weight based on 100 parts by weight of a total amount of LiCoO2and LCBA.

[0182] An all-solid-state battery was manufactured in the same manner as in Comparative Example 1 except that the positive electrode layer green sheet formed without the positive electrode current collecting layer was used instead of the positive electrode layer green sheet of Comparative Example 1. The all-solid-state battery cell was manufactured to have a structure shown in FIG. 5.

[0183] Types of the solid electrolytes used in Examples 1 to 3 and Comparative Examples 1 to 3 are summarized in Table 1.

[0184] StructureSolid electrolyteABCDEFExample 1FIG. 2LBSOLCBALBSOLCBALCBALCBAExample 2FIG. 4LBSOLCBA-LCBALCBALCBAExample 3FIG. 5-LCBALBSOLCBALCBALCBAComparative Example 1FIG. 2LCBALCBALCBALCBALCBALCBAComparative Example 2FIG. 4LCBALCBA-LCBALCBALCBAComparative Example 3FIG. 5-LCBALCBALCBALCBALCBA

[0185] Evaluation 1: Ionic Conductivity

[0186] The all-solid-state battery cells according to Examples 1 to 3 and Comparative Examples 1 to 3 were measured with respect to ionic conductivity of each of the solid electrolytes in the following method, and the results are shown in Table 2.

[0187] Each of the all-solid-state battery cells was broken into chips, which were polished or ion-milled to exposed an active material layer to sample a portion of the exposed active material layer as a rectangular hexahedron piece. Herein, the rectangular hexahedron sample had a shortest thickness (T) and a longer length (L) and width (W) than the thickness (T). In the obtained sample, an electrode formed of gold (Au) or platinum (Pt) was formed on the TW surface and then, connected to an impedance measuring apparatus. The impedance measuring apparatus was used to measure AC impedance under conditions of a frequency of 106Hz to 10-1Hz and a voltage of 50 mV to 500 mV at room temperature of 25 °C. The impedance measurement results were used with sizes of the samples to calculate the ionic conductivity of the solid electrolytes of the active material layers. Similarly, the ionic conductivity of the solid electrolyte of the current collecting layer was also measured in the same manners as above. Herein, because the ionic conductivity was difficult to measure, when the active materials or current collecting materials were mixed with the rectangular hexahedron samples, the measurement was performed where the active material and current collecting material were not respectively mixed in the sampling process.

[0188] Ionic conductivity (S / cm)Solid electrolyte A(positive electrode current collecting layer)Solid electrolyte B(positive electrode active material layer)Solid electrolyte C(negative electrode current collecting layer)Solid electrolyte D(negative electrode active material layer)Example 15.0 x 10-92.0 x 10-65.0 x 10-92.0 x 10-6Example 25.0 x 10-92.0 x 10-6-2.0 x 10-6Example 3-2.0 x 10-65.0 x 10-92.0 x 10-6Comparative Example 12.0 x 10-62.0 x 10-62.0 x 10-62.0 x 10-6Comparative Example 22.0 x 10-62.0 x 10-6-2.0 x 10-6Comparative Example 3-2.0 x 10-62.0 x 10-62.0 x 10-6

[0189] Referring to Table 2, Examples 1 to 3 exhibited lower ionic conductivity of the solid electrolyte of the current collecting layer than that of the active material layer. On the other hand, Comparative Examples 1 to 3 exhibited that the ionic conductivity of the solid electrolyte of the current collecting layer was almost the same as that of the active material layer.

[0190] Evaluation 2: SEM-EDS Analysis

[0191] The all-solid-state battery cell of Example 2 was subjected to SEM-EDS (scanning electron microscope-energy dispersive spectroscopy) analysis to check material components of the solid electrolyte.

[0192] FIG. 6 is a scanning electron microscope (SEM) image showing a cross-section of the all-solid-state battery cell of Example 2.

[0193] The all-solid-state battery cell was broken into chips, which were polished or ion-milled to obtain a cross-sectional sample in which the positive electrode active material layer and the positive electrode current collecting layer were exposed, and the cross-sectional sample was taken an SEM image under conditions of an acceleration voltage of 10 kV and a magnification of 5000 times. Subsequently, the obtained SEM image was subjected to EDS analysis, for example, as marked in FIG. 6, by designating any random point X in the positive electrode current collecting layer and any random point Y in the positive electrode active material layer.

[0194] As a result of the EDS analysis, elements of Co, Al, B, O, Cl, and C were detected in the positive electrode active material layer, but in the positive electrode current collecting layer, elements of C, O, Si, and Al were detected. In other words, the Si element detected in the positive electrode current collecting layer was not detected in the positive electrode active material layer. Accordingly, it was confirmed that the solid electrolyte of LBSO containing Si was used in the positive electrode current collecting layer, but the solid electrolyte of LCBA containing not Si but Cl was used in the positive electrode active material layer.

[0195] Evaluation 3: Occurrence of Micro-short

[0196] The all-solid-state battery cells according to Examples 1 to 3 and Comparative Examples 1 to 3 were measured with respect to a micro-short occurrence voltage in the following method, and the results are shown in Table 3.

[0197] The all-solid-state battery cells were connected to a charger and discharger and then, charged and discharged in a constant current method. Herein, the charging and discharging were performed at current density of 0.1 C within a range of a charge voltage of 4.3 V to a discharge voltage of 2.0 V after aging the cells for 2 hours before the charging and discharging. A point when micro-shorts occurred was defined as a point at which a voltage drop of 10 mV or more first occurred during the charging, wherein the micro-short occurrence voltage means a maximum voltage reached by the all-solid-state battery cells just before the first voltage drop. If the all-solid-state battery cells reached 4.3 V without the voltage drop during the charging, it was judged that no micro-shorts occurred.

[0198] Micro-short occurrence voltage (V)NoteExample 14.3Micro-short did not occurredExample 24.05Example 34.3Micro-short did not occurredComparative Example 13.95Comparative Example 23.95Comparative Example 33.95

[0199] Referring to Table 3, Examples 1 to 3, compared with Comparative Examples 1 to 3, exhibited a high micro-short occurrence voltage and almost no micro-shorts. Accordingly, when different types of solid electrolytes were not only included in at least one of the current collecting layers and at least one of the active material layers, but also when the solid electrolyte of the current collecting layers had lower ionic conductivity than that of the active material layers, the micro-shorts occurrences were reduced.

[0200] It is to be understood that although some embodiments of the present disclosure have been described above, the present disclosure is not limited thereto, but can be implemented in various modifications within the scope of the claims, the detailed description of the present disclosure, and the accompanying drawings, which also fall within the scope of the present disclosure.

[0201] <Description of Symbols>

[0202] 100, 200, 300: all-solid-state battery

[0203] 110: stack

[0204] 112, 114: external electrode

[0205] 120, 220, 320: positive electrode layer

[0206] 121, 221: first positive electrode active material layer

[0207] 122, 222: second positive electrode active material layer

[0208] 123, 223: positive electrode current collecting layer

[0209] 130, 230, 330: solid electrolyte layer

[0210] 140, 240, 340: negative electrode layer

[0211] 141, 341: first negative electrode active material layer

[0212] 142, 343: second negative electrode active material layer

[0213] 143, 343: negative electrode current collecting layer

[0214] 150, 250, 350: margin insulating layer

Claims

1.An all-solid-state battery, comprisinga positive electrode layer, a negative electrode layer, and a solid electrolyte layer stacked between the positive electrode layer and the negative electrode layer,wherein at least one of the positive electrode layer and the negative electrode layer includes a current collecting layer and an active material layer disposed on at least one surface of the current collecting layer,at least one of the current collecting layers and at least one of the active material layers include a solid electrolyte,the solid electrolyte of the current collecting layer has lower ionic conductivity than the solid electrolyte of the active material layer,the solid electrolyte of the current collecting layer includes at least one selected from a lithium borosilicate-based compound; and at least one oxide selected from B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3, andthe solid electrolyte of the active material layer includes at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound.2.The all-solid-state battery of claim 1, whereinthe ionic conductivity of the solid electrolyte of the current collecting layer is greater than or equal to 1.0E-12 S / cm and less than or equal to 1.0E-06 S / cm, andthe ionic conductivity of the solid electrolyte of the active material layer is greater than 1.0E-06 S / cm and less than or equal to 1.0E-02 S / cm.3.The all-solid-state battery of claim 1, whereinthe solid electrolyte of the current collecting layer includes a lithium borosilicate-based compound, andthe solid electrolyte of the active material layer includes a lithium chloroboracite-based compound.4.The all-solid-state battery of claim 1, whereinthe solid electrolyte layer includes a solid electrolyte, andthe solid electrolyte of the solid electrolyte layer has higher ionic conductivity than the solid electrolyte of the current collecting layer.5.The all-solid-state battery of claim 1, whereinthe all-solid-state battery further includes a margin insulating layer, which is a region excluding a region where the positive electrode layer or the negative electrode layer is disposed on the solid electrolyte layer,the margin insulating layer includes a solid electrolyte, andthe solid electrolyte of the margin insulating layer has higher ionic conductivity than the solid electrolyte of the current collecting layer.6.An all-solid-state battery, comprisinga positive electrode layer, a negative electrode layer, and a solid electrolyte layer stacked between the positive electrode layer and the negative electrode layer,wherein the positive electrode layer includes a positive electrode current collecting layer including a solid electrolyte, and a positive electrode active material layer disposed on at least one surface of the positive electrode current collecting layer and including a solid electrolyte,the negative electrode layer includes a negative electrode current collecting layer including a solid electrolyte, and a negative electrode active material layer disposed on at least one surface of the negative electrode current collecting layer and including a solid electrolyte,the solid electrolyte of the positive electrode current collecting layer, the solid electrolyte of the positive electrode active material layer, the solid electrolyte of the negative electrode current collecting layer, and the solid electrolyte of the negative electrode active material layer are the same or different from each other,at least one of the solid electrolyte of the positive electrode current collecting layer and the solid electrolyte of the negative electrode current collecting layer has lower ionic conductivity than at least one of the solid electrolyte of the positive electrode active material layer and the solid electrolyte of the negative electrode active material layer,at least one of the solid electrolyte of the positive electrode current collecting layer and the solid electrolyte of the negative electrode current collecting layer includes at least one selected from a lithium borosilicate-based compound; and at least one oxide selected from B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3, andat least one of the solid electrolyte of the positive electrode active material layer and the solid electrolyte of the negative electrode active material layer includes at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound.7.The all-solid-state battery of claim 6, whereinthe solid electrolyte of the positive electrode current collecting layer has lower ionic conductivity than at least one of the solid electrolyte of the positive electrode active material layer and the solid electrolyte of the negative electrode active material layer, andthe solid electrolyte of the negative electrode current collecting layer has lower ionic conductivity than at least one of the solid electrolyte of the negative electrode active material layer and the solid electrolyte of the positive electrode active material layer.8.The all-solid-state battery of claim 6, whereinthe ionic conductivity of at least one of the solid electrolyte of the positive electrode current collecting layer and the solid electrolyte of the negative electrode current collecting layer is greater than or equal to 1.0E-12 S / cm and less than or equal to 1.0E-06 S / cm, andthe ionic conductivity of at least one of the solid electrolyte of the positive electrode active material layer and the solid electrolyte of the negative electrode active material layer is greater than 1.0E-06 S / cm and less than or equal to 1.0E-02 S / cm.9.The all-solid-state battery of claim 6, whereinat least one of the solid electrolyte of the positive electrode current collecting layer and the solid electrolyte of the negative electrode current collecting layer includes a lithium borosilicate-based compound, andat least one of the solid electrolyte of the positive electrode active material layer and the solid electrolyte of the negative electrode active material layer includes a lithium chloroboracite-based compound.10.The all-solid-state battery of claim 6, whereinthe solid electrolyte of the positive electrode current collecting layer and the solid electrolyte of the negative electrode current collecting layer include a lithium borosilicate-based compound, andthe solid electrolyte of the positive electrode active material layer and the solid electrolyte of the negative electrode active material layer include a lithium chloroboracite-based compound.11.The all-solid-state battery of claim 6, whereinthe solid electrolyte layer includes a solid electrolyte, andthe solid electrolyte of the solid electrolyte layer has higher ionic conductivity than at least one of the solid electrolyte of the positive electrode current collecting layer and the solid electrolyte of the negative electrode current collecting layer.12.An all-solid-state battery, comprisinga positive electrode layer, a negative electrode layer, and a solid electrolyte layer stacked between the positive electrode layer and the negative electrode layer,wherein the positive electrode layer includes a positive electrode current collecting layer including a solid electrolyte, and a positive electrode active material layer disposed on at least one surface of the positive electrode current collecting layer and including a solid electrolyte,the negative electrode layer includes a negative electrode active material layer including a solid electrolyte,the solid electrolyte of the positive electrode current collecting layer, the solid electrolyte of the positive electrode active material layer, and the solid electrolyte of the negative electrode active material layer are the same or different from each other,the solid electrolyte of the positive electrode current collecting layer has lower ionic conductivity than at least one of the solid electrolyte of the positive electrode active material layer and the solid electrolyte of the negative electrode active material layer,the solid electrolyte of the positive electrode current collecting layer includes at least one selected from a lithium borosilicate-based compound; and at least one oxide selected from B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3, andat least one of the solid electrolyte of the positive electrode active material layer and the solid electrolyte of the negative electrode active material layer includes at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound.13.The all-solid-state battery of claim 12, whereinthe ionic conductivity of the solid electrolyte of the positive electrode current collecting layer is greater than or equal to 1.0E-12 S / cm and less than or equal to 1.0E-06 S / cm, andthe ionic conductivity of at least one of the solid electrolyte of the positive electrode active material layer and the solid electrolyte of the negative electrode active material layer is greater than 1.0E-06 S / cm and less than or equal to 1.0E-02 S / cm.14.The all-solid-state battery of claim 12, whereinthe solid electrolyte of the positive electrode current collecting layer includes a lithium borosilicate-based compound, andat least one of the solid electrolyte of the positive electrode active material layer and the solid electrolyte of the negative electrode active material layer includes a lithium chloroboracite-based compound.15.The all-solid-state battery of claim 12, whereinthe solid electrolyte of the positive electrode current collecting layer includes a lithium borosilicate-based compound,the solid electrolyte of the positive electrode active material layer and the solid electrolyte of the negative electrode active material layer include a lithium chloroboracite-based compound.16.The all-solid-state battery of claim 12, whereinthe solid electrolyte layer includes a solid electrolyte, andthe solid electrolyte of the solid electrolyte layer has higher ionic conductivity than the solid electrolyte of the positive electrode current collecting layer.17.An all-solid-state battery, comprisinga positive electrode layer, a negative electrode layer, and a solid electrolyte layer stacked between the positive electrode layer and the negative electrode layer,wherein the positive electrode layer includes a positive electrode active material layer including a solid electrolyte,the negative electrode layer includes a negative electrode current collecting layer including a solid electrolyte, and a negative electrode active material layer disposed on at least one surface of the negative electrode current collecting layer and including a solid electrolyte,the solid electrolyte of the positive electrode active material layer, the solid electrolyte of the negative electrode current collecting layer, and the solid electrolyte of the negative electrode active material layer are the same or different from each other,the solid electrolyte of the negative electrode current collecting layer has lower ionic conductivity than at least one of the solid electrolyte of the negative electrode active material layer and the solid electrolyte of the positive electrode active material layer,the solid electrolyte of the negative electrode current collecting layer includes at least one selected from lithium borosilicate-based compound; and at least one oxide selected from B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, and Y2O3, andat least one of the solid electrolyte of the negative electrode active material layer and the solid electrolyte of the positive electrode active material layer includes at least one selected from a lithium chloroboracite-based compound, a garnet-type compound, and a LISICON-type compound.18.The all-solid-state battery of claim 17, whereinthe ionic conductivity of the solid electrolyte of the negative electrode current collecting layer is greater than or equal to 1.0E-12 S / cm and less than or equal to 1.0E-06 S / cm, andthe ionic conductivity of at least one of the solid electrolyte of the negative electrode active material layer and the solid electrolyte of the positive electrode active material layer is greater than 1.0E-06 S / cm and less than or equal to 1.0E-02 S / cm.19.The all-solid-state battery of claim 17, whereinthe solid electrolyte of the negative electrode current collecting layer includes a lithium borosilicate-based compound, andat least one of the solid electrolyte of the negative electrode active material layer and the solid electrolyte of the positive electrode active material layer includes a lithium chloroboracite-based compound.20.The all-solid-state battery of claim 17, whereinthe solid electrolyte of the negative electrode current collecting layer includes a lithium borosilicate-based compound, andthe solid electrolyte of the negative electrode active material layer and the solid electrolyte of the positive electrode active material layer include a lithium chloroboracite-based compound.21.An all-solid-state battery, comprising:an electrode layer comprising:a current collecting layer comprising a first solid electrolyte material including a lithium borosilicate compound and an oxide selected from the group consisting of B2O3, GeO, P2O5, Al2O3, BaTiO3, SiO2, Li2O, MgO, ZrO2, TiO2, Y2O3, and a combination thereof, andan active material layer disposed on at least one surface of the current collecting layer and comprising a second solid electrolyte material selected from the group consisting of a lithium chloroboracite-based compound, a garnet-type compound, a LISICON-type compound, and a combination thereof; anda solid electrolyte layer comprising a third solid electrolyte material and contacting the electrode layer,wherein ionic conductivity of the first solid electrolyte material is lower than that of the second solid electrolyte material, andwherein ionic conductivity of the third solid electrolyte material is higher than that of the first solid electrolyte material.22.The all-solid-state battery of claim 21, further including a margin insulating layer, which is a region excluding a region where the electrode layer is disposed on the solid electrolyte layer, wherein:the margin insulating layer includes a fourth solid electrolyte, andthe fourth solid electrolyte has higher ionic conductivity than the first solid electrolyte.23.The all-solid-state battery of claim 21, wherein the electrode layer comprises a positive electrode layer and a negative electrode layer with the solid electrolyte layer stacked therebetween.24.The all-solid-state battery of claim 23, wherein the active material layer of each of the positive and the negative electrode layers contacts the solid electrolyte layer stacked therebetween.25.The all-solid-state battery of claim 21, wherein the ionic conductivity of the first solid electrolyte is in a range from 1.0E-12 S / cm to 1.0E-06 S / cm, andthe ionic conductivity of the second solid electrolyte is in a range from 1.0E-06 S / cm to 1.0E-02 S / cm.

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